Fat burning is a very popular and often-used term among endurance athletes. But is it really important to burn fat – and, if so, how can it best be achieved? Asker [...]]]> In this article the fat burning processes are well explained and the latest scientific research dispels many popular myths. Mike

Fat oxidation through intense exercise

Fat burning is a very popular and often-used term among endurance athletes. But is it really important to burn fat – and, if so, how can it best be achieved? Asker Jeukendrup looks at the latest research

The term ‘fat burning’ refers to the ability to oxidise (or burn) fat, and thus to use fat – instead of carbohydrate – as a fuel. Fat burning is often associated with weight loss, decreases in body fat and increases in lean body mass, all of which can be advantageous for an athlete.

It is known that well-trained endurance athletes have an increased capacity to oxidise fatty acids. This enables them to use fat as a fuel when their carbohydrate stores become limited. In contrast, patients with obesity, insulin resistance and type II diabetes may have an impaired capacity to oxidise fat. As a result, fatty acids may be stored in their muscles and in other tissues. This accumulation of lipid and its metabolites in the muscle may interfere with the insulin-signalling cascade and cause insulin resistance. It is therefore important to understand the factors that regulate fat metabolism, and the ways to increase fat oxidation in patients and athletes.

Fat oxidation during exercise

Fats are stored mostly in (subcutaneous) adipose tissue, but we also have small stores in the muscle itself (intramuscular triglycerides). At the onset of exercise, neuronal (beta-adrenergic) stimulation will increase lipolysis (the breakdown of fats into fatty acids and glycerol) in adipose tissue and muscle. Catecholamines such as adrenaline and noradrenaline may also rise and contribute to the stimulation of lipolysis.

As soon as exercise begins, fatty acids are mobilised. Adipose tissue fatty acids have to be transported from the fat cell to the muscle, be transported across the muscle membrane and then be transported across the mitochondrial membrane for oxidation. The triglycerides stored in muscle undergo similar lipolysis and these fatty acids can be transported into the mitochondria as well. During exercise, a mixture of fatty acids derived from adipocytes and intramuscular stores is used. There is evidence that shows that trained individuals store more intramuscular fat and use this more as a source of energy during exercise (1).

Fat oxidation is regulated at various steps of this process. Lipolysis is affected by many factors but is mostly regulated by hormones (stimulated by catecholamines and inhibited by insulin). The transport of fatty acids is also dependent on blood supply to the adipose and muscle tissues, as well as the uptake of fatty acids into the muscle and into the mitochondria. By inhibiting mobilisation of fatty acids or the transport of these fatty acids, we can reduce fat metabolism. However, are there also ways in which we can stimulate these steps
and promote fat metabolism?

Factors affecting fat oxidation

Exercise intensity – One of the most important factors that determines the rate of fat oxidation during exercise is the intensity. Although several studies have described the relationship between exercise intensity and fat oxidation, only recently was this relationship studied over a wide range of intensities(2). In absolute terms, carbohydrate oxidation increases proportionally with exercise intensity, whereas the rate of fat oxidation initially increases, but decreases again at higher exercise intensities (see figure 1). So, although it is often claimed that you have to exercise at low intensities to oxidise fat, this is not necessarily true.

In a series of recent studies, we have defined the exercise intensity at which maximal fat oxidation is observed, called ‘Fatmax’. In a group of trained individuals it was found that exercise at moderate intensity (62-63% of VO2max or 70-75% of HRmax) was the optimal intensity for fat oxidation, whereas it was around 50% of VO2max for less trained individuals (2,3).

However, the inter-individual variation is very large. A trained person may have his or her maximal fat oxidation at 70%VO2max or 45%VO2max, and the only way to really find out is to perform one of these Fatmax tests in the laboratory. However, in reality, the exact intensity at which fat oxidation peaks may not be that important, because within 5-10% of this intensity (or 10-15 beats per minute), fat oxidation will be similarly high, and only when the intensity is 20% or so higher will fat oxidation drop rapidly (see figure 1).

This exercise intensity (Fatmax) or ‘zone’ may have importance for weight-loss programmes, health-related exercise programmes, and endurance training. However, very little research has been done. Recently we used this intensity in a training study with obese individuals. Compared with interval training, their fat oxidation (and insulin sensitivity) improved more after four weeks steady-state exercise (three times per week) at an intensity that equalled their individual Fatmax (4).

Dietary effects – The other important factor is diet. A diet high in carbohydrate will suppress fat oxidation, and a diet low in carbohydrate will result in high fat oxidation rates. Ingesting carbohydrate in the hours before exercise will raise insulin and subsequently suppress fat oxidation by up to 35%(5) or thereabouts. This effect of insulin on fat oxidation may last as long as six to eight hours after a meal, and this means that the highest fat oxidation rates can be achieved after an overnight fast.

Endurance athletes have often used exercise without breakfast as a way to increase the fat-oxidative capacity of the muscle. Recently, a study was performed at the University of Leuven in Belgium, in which scientists investigated the effect of a six-week endurance training programme carried out for three days per week, each session lasting one to two hours(6). The participants trained in either the fasted or carbohydrate-fed state.

When training was conducted in the fasted state, the researchers observed a decrease in muscle glycogen use, while the activity of various proteins involved in fat metabolism was increased. However, fat oxidation during exercise was the same in the two groups. It is possible, though, that there are small but significant changes in fat metabolism after fasted training; but, in this study, changes in fat oxidation might have been masked by the fact that these subjects received carbohydrate during their experimental trials. It must also be noted that training after an overnight fast may reduce your exercise capacity and may therefore only be suitable for low- to moderate- intensity exercise sessions. The efficacy of such training for weight reduction is also not known.

Duration of exercise – It has long been established that oxidation becomes increasingly important as exercise progresses. During ultra-endurance exercise, fat oxidation can reach peaks of 1 gram per minute, although (as noted in Dietary effects)fat oxidation may be reduced if carbohydrate is ingested before or during exercise. In terms of weight loss, the duration of exercise may be one of the key factors as it is also the most effective way to increase energy expenditure.

Mode of exercise – The exercise modality also has an effect on fat oxidation. Fat oxidation has been shown to be higher for a given oxygen uptake during walking and running, compared with cycling(7). The reason for this is not known, but it has been suggested that it is related to the greater power output per muscle fibre in cycling compared to that in running.

Gender differences – Although some studies in the literature have found no gender differences in metabolism, the majority of studies now indicate higher rates of fat oxidation in women. In a study that compared 150 men and 150 women over a wide range of exercise intensities, it was shown that the women had higher rates of fat oxidation over the entire range of intensities, and that their fat oxidation peaked at a slightly higher intensity(8). The differences, however, are small and may not be of any physiological significance.

Nutrition supplements

There are many nutrition supplements on the market that claim to increase fat oxidation. These supplements include caffeine, carnitine, hydroxycitric acid (HCA), chromium, conjugated linoleic acid (CLA), guarana, citrus aurantium, Asian ginseng, cayenne pepper, coleus forskholii, glucomannan, green tea, psyllium and pyruvate. With few exceptions, there is little evidence that these supplements, which are marketed as fat burners, actually increase fat oxidation during exercise (see table 1).

One of the few exceptions however may be green tea extracts. We recently found that green tea extracts increased fat oxidation during exercise by about 20%(4). The mechanisms of this are not well understood but it is likely that the active ingredient in green tea, called epigallocatechin gallate (EGCG – a powerful polyphenol with antioxidant properties) inhibits the enzyme catechol O-methyltransferase (COMT), which is responsible for the breakdown of noradrenaline. This in turn may result in higher concentrations of noradrenaline and stimulation of lipolysis, making more fatty acids available for oxidation.

Environment – Environmental conditions can also influence the type of fuel used. It is known that exercise in a hot environment will increase glycogen use and reduce fat oxidation, and something similar can be observed at high altitude. Similarly, when it is extremely cold, and especially when shivering, carbohydrate metabolism appears to be stimulated at the expense of fat metabolism.

Exercise training

At present, the only proven way to increase fat oxidation during exercise is to perform regular physical activity. Exercise training will up-regulate the enzymes of the fat oxidation pathways, increase mitochondrial mass, increase blood flow, etc., all of which will enable higher rates of fat oxidation.

Research has shown that as little as four weeks of regular exercise (three times per week for 30-60 minutes) can increase fat oxidation rates and cause favourable enzymatic changes(10). However, too little information is available to draw any conclusions about the optimal training programme to achieve these effects.

In one study we investigated maximal rates of fat oxidation in 300 subjects with varying fitness levels. In this study, we had obese and sedentary individuals, as well as professional cyclists (9). VO2max ranged from 20.9 to 82.4ml/kg/min. Interestingly, although there was a correlation between maximal fat oxidation and maximal oxygen uptake, at an individual level, fitness cannot be used to predict fat oxidation. What this means is that there are some obese individuals that have similar fat oxidation rates to professional cyclists (see figure 2)! The large inter-individual variation is related to factors such as diet and gender, but remains in large part unexplained.

Weight loss exercise programmes

Fat burning is often associated with weight loss, decreases in body fat and increases in lean body mass. However, it must be noted that such changes in body weight and body composition can only be achieved with a negative energy balance: you have to eat fewer calories than you expend, independent of the fuels you use! The optimal exercise type, intensity, and duration for weight loss are still unclear. Current recommendations are mostly focused on increasing energy expenditure and increasing exercise volumes. Finding the optimal intensity for fat oxidation might aid in losing weight (fat loss) and in weight maintenance, but evidence for this is currently lacking.
It is also important to realise that the amount

of fat oxidised during exercise is only small. Fat oxidation rates are on average 0.5 grams per min at the optimal exercise intensity. So in order to oxidise 1kg of fat mass, more than 33 hours of exercise is required! Walking or running exercise around 50-65% of VO2max seems to be an optimal intensity to oxidise fat. The duration of exercise, however, plays a crucial role, with an increasing importance of fat oxidation with longer exercise. Of course, this also has the potential to increase daily energy expenditure. If exercise is the only intervention used, the main goal is usually to increase energy expenditure and reduce body fat. When combined with a diet programme, however, it is mainly used to counteract the decrease in fat oxidation often seen after weight loss (11).

Summary

Higher fat oxidation rates during exercise are generally reflective of good training status, whereas low fat oxidation rates might be related to obesity and insulin resistance. On average, fat oxidation peaks at moderate intensities of 50-65%VO2max, depending on the training status of the individuals(2,8), increases with increasing exercise duration, but is suppressed by carbohydrate intake. The vast majority of nutrition supplements do not have the desired effects. Currently, the only highly effective way to increase fat oxidation is through exercise training, although it is still unclear what the best training regimen is to get the largest improvements. Finally, it is important to note that there is a very large inter-individual variation in fat oxidation that is only partly explained by the factors mentioned above. This means that although the factors mentioned above can influence fat oxidation, they cannot predict fat oxidation rates in an individual.

Asker Jeukendrup is professor of exercise metabolism at the University of Birmingham. He has published more than 150 research papers and books on exercise metabolism and nutrition and is also consultant to many elite athletes

References
1. J Appl Physiol 60: 562-567, 1986
2. Int J Sports Med 24: 603-608, 2003
3. Int J Sports Med 26 Suppl 1: S28-37, 2005
4. Am J Clin Nutr 87: 778-784, 2008
5. J Sports Sci 21: 1017-1024, 2003
6. J Appl Physiol 104: 1045-1055, 2008
7. Metabolism 52: 747-752, 2003
8. J Appl Physiol 98: 160-167, 2005
9. Nutrition 20: 678-688, 2004
10. J Appl Physiol 56: 831-838, 1984
11. Int J Obes Relat Metab Disord 17 Suppl 3: S32-36; discussion S41-32, 1993

Don’t miss out on hundreds of vital training workouts and cutting edge research.
Trial Peak Performance today for just $9.97.

Tags: triathlon wetsuits, duathlon

More in the series on recovery and the prevention of overtraining which again emphasises the importance of having a good balanced nutrition programme. – Mike

Where should we draw the line between appropriate ‘heavy training’ and overtraining? And are there specific nutritional practices that can prevent [...]]]>

More in the series on recovery and the prevention of overtraining which again emphasises the importance of having a good balanced nutrition programme. – Mike

Specific nutritional practices can prevent overtraining and accelerate exercise recovery

Where should we draw the line between appropriate ‘heavy training’ and overtraining? And are there specific nutritional practices that can prevent overtraining and accelerate exercise recovery? Mike Saunders explains and shows that these two concepts are intimately linked.

In simple terms, overtraining is the result of intense training stimuli (and other stressors) combined with inadequate recovery. If appropriate recovery is not provided during hard training, you experience a downward spiral in which continued heavy training creates diminishing returns, and performance levels continue to get worse. However, determining precisely when the ‘overtraining line’ is crossed is very difficult. This is because the symptoms of overtraining are highly individualised and varied – a laundry list of physical, psychological, immunological and biochemical symptoms.

A consistent end result of overtraining is the impairment of physical performance. When you are overtrained, you can expect to see elevated perceptions of exertion/fatigue during exercise, decreased movement economy, slower reaction time and impaired performance times. To make things worse, overtraining status is usually only diagnosed with the benefit of hindsight. In other words, by the time you know you are overtrained, it is too late to handle it effectively!

Overtraining terminology

Recently, the terminology around overtraining has been improved. Researchers from the Netherlands and Belgium have described the overtraining process as occurring in three progressive stages (see box 1)(1):

1. Functional overreaching
2. Non-functional overreaching
3. Overtraining syndrome

Functional overreaching is the normal process of fatigue that occurs with sustained periods of heavy training. Although these periods of hard training cause short-term impairments in performance, this effect is reversed with a relatively short pre-planned recovery period. For example, a 1-week block of hard training may cause moderate levels of fatigue, impairing your peak performance for a few days. However, when you balance this hard training period with a period of adequate recovery, you can quickly return to a level matching and ultimately exceeding your initial level of performance.
Non-functional overreaching is a more severe level of fatigue reached when your performance and energy are not restored after a planned short-term recovery period. This often happens if you work too hard during your recovery days, if you underestimate the impact of the non-training stresses in your life, or if you simply train too long and hard before a recovery period. As a result, you may still feel fatigued following your planned recovery period. This is where flexibility in your training programme becomes very important. If coaches recognise the continued fatigue of an athlete, they can delay the next heavy training phase or competition. This is often enough to reverse the fatigue and restore performance levels.

However, if coaches and athletes ignore fatigue in the non-functional overreaching stage, further heavy training simply results in deeper levels of fatigue. This can become a vicious cycle in which athletes continue heavy training in an attempt to reverse their declining performance, only to exacerbate the problem by further impairing their recovery. True overtraining syndrome is reached only in the most severe cases, and can be quite debilitating. Symptoms of overtraining syndrome overlap with chronic fatigue syndrome and clinical depression, and can only be reversed with several weeks or months of recovery(1).

Balancing training and recovery

The model of overtraining discussed above illustrates the critical balance of well-timed recovery periods within a training program. Your training phases can be specifically designed to cause functional overreaching at strategic times. However, effective training programmes are  created to include adequate recovery to prevent both non-functional overreaching and overtraining syndrome.

As an example, professional cyclists often perform team training camps that provide a significant early-season training stimulus. The volume of training performed at these camps can induce significant fatigue. However, training camps can produce important improvements in performance if the heavy training is balanced with an appropriate period of short-term recovery.

Recent studies from our Human Performance Laboratory at James Madison University (USA) provide some quantitative evidence to support these concepts. We studied professional cyclists who completed at least three consecutive days of high-volume training, averaging almost 100 miles/day. Not surprisingly, the heavy training caused significant changes in a number of overreaching/overtraining symptoms. These included increased levels of mental and physical fatigue, increased muscle soreness and elevated markers of muscle damage.

About half of the cyclists then performed an ‘easy’ day of training on the fourth day – about 30 miles at low intensity. For these highly trained athletes, this was enough recovery to initiate improvement of all of the symptoms mentioned above.

Overtraining and diet

Appropriate nutrient intake and timing can play an important role in influencing the overtraining process. It has long been established that adequate carbohydrate intake is required to maintain muscle glycogen levels during heavy training. This is critical to sustaining high training volumes, as muscle glycogen is a primary fuel stored in muscles and used during endurance training and racing. In addition, we know that exercise stimulates enhanced uptake of carbohydrate in the muscles. This so-called ‘insulin-like effect’ of exercise remains for a short time following exercise. As a result, the consumption of carbohydrate immediately after training (within 30 minutes) produces faster replenishment of muscle glycogen than if carbohydrate intake is delayed. Thus, it is now common practice for endurance athletes to consume a carbohydrate-rich recovery beverage or snack immediately following demanding training sessions.

More recently, scientists have begun to investigate how carbohydrate intake and timing influence specific aspects of the overtraining process. Researchers from the University of Birmingham examined how dietary carbohydrate intake influenced overreaching symptoms during a period of intensified running training(2). When performing 11 days of intensified training consuming relatively low carbohydrate intake (5.4 grams per kilo of bodyweight per day), the runners experienced significant worsening in mood states, fatigue, muscle soreness, and declines in running performance. These factors were considerably (though not entirely) reversed when the athletes performed the same training demands with higher carbohydrate (8.5g/kg/day) in their diets.

The same research group performed a similar study in cyclists(3). Athletes consumed sports beverages with low or high carbohydrate content during exercise (low=2%; high=6%) and immediately following exercise (low=2%; high=20%). When consuming the low-carbohydrate drinks over eight days of intensified training, the athletes experienced significant declines in their mood states, increased perceived effort during exercise, and declines in cycling performance. All of these factors improved when the high-carbohydrate beverages were consumed during/following training.

Following the eight-day period of intensified training, the cyclists received fourteen days of reduced volume training to promote recovery. This resulted in significant improvements in cycling performance (exceeding baseline levels) but only when the athletes drank the high-carbohydrate beverages. By contrast, performance remained suppressed below baseline levels with the low-carbohydrate drinks.

Thus, altering the carbohydrate levels of the cyclists’ sports drinks was enough to influence their responses to training. As a result, the intensified training represented a functional overreaching stimulus when appropriate carbohydrate was provided, but a non-functional overreaching stimulus without adequate carbohydrate. This is an excellent illustration of how ‘optimal recovery’ represents much more than simply lowering the demands of training (see figure 1).

Co-ingestion of carbohydrate and protein

The effects of protein intake on recovery from endurance training have been understudied compared to carbohydrate. As a result, there is no clear consensus among scientists regarding the role that protein plays in the overtraining process. However, recent studies suggest that there may be some additional recovery benefits associated with consuming a mix of carbohydrate and protein following heavy endurance training.

Carbohydrate-protein and glycogen replenishment Combined intake of carbohydrate-protein may influence a number of factors that are important for recovery in endurance athletes. For example, some studies have shown faster rates of muscle glycogen replenishment when carbohydrate-protein is consumed immediately following endurance exercise (compared to carbohydrate alone).

Other studies have suggested that the additional benefits of added protein are negligible if the carbohydrate doses are very high (over 1.2 g/kg). At a minimum, it appears that carbohydrate-protein ingestion is a highly practical way to ensure high rates of glycogen replenishment following exercise, especially when you are not consuming a high-calorie recovery drink or snack. This is particularly relevant in conjunction with the other potential benefits of carbohydrate-protein ingestion discussed below.

Carbohydrate-protein and protein balance Combined carbohydrate-protein intake may also have positive effects on protein balance for endurance athletes. Researchers at Maastricht University in Holland observed that carbohydrate-protein consumption increased protein synthesis and decreased protein breakdown in endurance athletes, compared to when they consumed carbohydrate alone(4).

Investigators at McMaster University (Canada) made similar observations of enhanced protein balance with carbohydrate-protein ingestion following aerobic exercise(5). In addition, they reported that the fractional synthetic rate (FSR) within the muscle was improved with carbohydrate-protein intake (see figure 2, overleaf). Collectively, these studies suggest that protein synthesis in the muscle may be improved with carbohydrate-protein intake. Though the long-term effects of improved protein synthesis and protein balance have not been studied in endurance athletes, this evidence suggests that protein may be helpful in stimulating muscle recovery and promoting positive muscle adaptations following heavy endurance training.

Carbohydrate-protein and muscle recovery Carbohydrate-protein ingestion has been associated with improvements in various other markers of muscle recovery in endurance athletes. For example, researchers from our Human Performance Laboratory at James Madison University have observed that carbohydrate-protein ingestion results in lower blood creatine kinase (CK) levels (an indicator of muscle damage)(6,7), less muscle soreness(7), and improved muscle function(6)following heavy endurance exercise (see Figure 2).

We have observed these benefits in carbohydrate-protein versus carbohydrate-only drinks matched for both carbohydrate content and total calories(6). In addition, we have observed these effects when we studied carbohydrate-protein beverages consumed during endurance exercise(6) or immediately following exercise(7). In one study, we examined carbohydrate and carbohydrate-protein recovery beverages during six days of consecutive training in collegiate distance runners(7). While consuming the drinks containing carbohydrate-protein, the athletes had lower blood CK levels and less muscle soreness, despite performing identical training loads between the two periods.

Carbohydrate-protein and subsequent performance

A critical question for coaches and athletes is whether the improved muscle recovery markers observed when consuming carbohydrate-protein drinks relates to any tangible benefits with respect to sport-specific performance. In other words, if carbohydrate-protein intake improves ‘recovery’, does this lead to enhanced performance during subsequent exercise?

Studies investigating this issue to date have produced mixed findings. For example, in our aforementioned study of runners, we did not observe differences in running performance following the six-day training period between the two beverages. However, this was probably due to the fact that the athletes were reducing their training levels in preparation for a race. Thus, they were probably well recovered prior to the race under both beverage conditions.
This evidence leads to an important observation: no supplement can be expected to enhance your recovery if you are already fully recovered. If you only perform light exercise, and take relatively long recovery periods between workouts, then the composition of your post-exercise nutrition regimen is far less critical, and perhaps irrelevant altogether if your regular diet is appropriate. However, if you perform heavy exercise on a regular basis, then it is important that your recovery nutrition includes adequate carbohydrate to maximise your post-exercise recovery. Under these conditions of heavy exercise and short recovery periods, it also seems likely that carbohydrate-protein sustains high performance levels better than carbohydrate alone.

Evidence supporting this concept can be observed in recent studies on this topic, including our study of runners discussed above. As mentioned previously, carbohydrate-protein did not produce performance improvements in runners who were tapering slightly prior to a race. However, the athletes who continued to perform the highest training mileage throughout the six days had the greatest improvements in muscle recovery with the carbohydrate-protein. This same group of ‘harder-training’ athletes also had a stronger tendency towards faster race performance with the carbohydrate-protein drink.

More convincingly, US researchers at the University of California-Davis examined the effects of carbohydrate-protein drinks during a short period of heavy cycling training(8). They assessed changes in blood CK and time to fatigue during three consecutive days of exercise. These variables got significantly worse over the three days of hard training when the cyclists consumed carbohydrate-only drinks. However, these declines were prevented when carbohydrate-protein drinks were consumed.

Similarly, researchers from Canada tested recovery and performance during two 60-minute cycling performance tests, separated by six hours(9). Carbohydrate or carbohydrate-protein recovery drinks were provided immediately after the first exercise trial. The cyclists were able to generate higher power output and better performance in the second exercise session following the carbohydrate-protein beverage, compared to the carbohydrate-only drink.
Not all studies have shown significant improvements in subsequent performance following carbohydrate-protein intake. However, the positive effects of protein seem to appear more regularly in the studies that provide the more demanding training/recovery periods. Thus, the longer and harder you train, the more important the details of your recovery nutrition, including the inclusion of protein, become.

The bottom line

In summary, overtraining is a complex issue, which can have important consequences for endurance athletes. Functional overreaching can be an intended outcome of heavy training periods, provided it is balanced with an appropriate period of recovery. The consumption of adequate nutrients, especially in the period immediately following heavy exercise training, can augment recovery from exercise. Thus, recovery nutrition can assist in the prevention of non-functional overreaching, and allow you to get the most out of your training. In short, this means making sure that your daily carbohydrate intake (especially immediately post-exercise) is adequately high to maintain your muscle glycogen levels during training. In addition, adding protein to your post-exercise recovery drinks and meals appears to have further benefits to promote optimal recovery from heavy exercise.

References

1. Sports Med 2006; 36: 817-828
2. J Appl Physiol 2004; 96: 1331-1340
3. J Appl Physiol 2004; 97: 1245-1253
4. Am J Physiol Endocrinol Metab 2004; 287:E712-E720
5. J Appl Physiol 2009; 106: 1394-1402
6. Int J Sports Nutr Exerc Metab 2008; 18 :363-378
7. Int J Sports Nutr Exerc Metab 2006; 16: 78-91
8. Int J Sports Nutr Exerc Metab 2008; 18 : 473-492
9. J Int Soc Sports Nutr 2009; 5(24): [in press]

Don’t miss out on hundreds of vital training workouts and cutting edge research.
Trial Peak Performance today for just $9.97.

Tags: triathlon, duathlon

Medium-chain triglycerides (MCTs) are a special class of fatty acids. Normal fats and oils contain long-chain fatty acids (LCTs). [...]]]> This is a follow up article on the previous one I posted entitled “Sports Nutrition – It is essential you include fat in your diet” and which expands on the use of medium-chain triglycerides (MCTs). Mike.

Medium-chain triglycerides (MCTs) are a special class of fatty acids. Normal fats and oils contain long-chain fatty acids (LCTs). Compared to these fatty acids, MCTs are much shorter in length. Therefore, they resemble carbohydrates more than fat. As a result, they are more easily absorbed, digested, and utilized as energy than LCTs.

Medium-chain triglycerides are found naturally in milk fat, palm oil, and coconut oil. Commercial MCT oil, available as liquid and capsules, is obtained through lipid fractionation, the process in which MCTs are separated from other components of coconut oil. Medium-chain triglycerides were originally formulated in the 1950s as an alternative food source for patients who are too ill to properly digest normal fats and oils. The long chains of LCTs require a lot of bile acids and many digestive steps to be broken down into smaller units that can be absorbed into the bloodstream. Once in the bloodstream, they are absorbed by fat cells and stored as body fat. In contrast, the medium-chain triglycerides are more water-soluble and are able to enter the bloodstream quicker because of their shorter lengths. Once in the bloodstream, they are transported directly into the liver. Thus, MCTs are an immediately available source of energy and only a tiny percent is converted into body fat.

Medium-chain triglycerides were first used in the mid-1900s to reduce seizures with the help of the ketogenic diet. In the 1980s, MCTs became popular in sports as a substitute for normal dietary fats or oils. They quickly became a favorite energy source for many athletes, such as marathon runners, who participate in endurance sports. These athletes require a quick source of energy, which is readily supplied by carbohydrates. However, diets high in carbohydrates may cause rapid increase in insulin production, resulting in substantial weight gain, diabetes, and other health problems. Dietary fats or oils are not a readily available source of energy. In addition, they are believed to make the body fatter. MCT is also a form of fat; therefore, it is high in calories. Yet, unlike normal fats and oils, MCTs do not cause weight gain because they stimulate thermogenesis (the process in which the body generates energy, or heat, by increasing its normal metabolic, fat-burning rate). A thermogenic diet, which is high in medium-chain triglycerides, has been proposed as a type of weight loss regime.

General Use

Endurance Sport Nutrition

Medium-chain triglycerides are often used by athletes to increase their endurance during sports or exercise regimes. MCTs are an immediate source of energy, and as such, the body can use them as an alternative energy source for muscle during endurance exercise. However, if consumed in moderate amounts (30 to 45 grams), MCTs are not very effective in either decreasing carbohydrate needs or in enhancing exercise endurance. Increased consumption may help. One study evaluated six athletes at different points during a 25-mile cycling trial. They were given either a medium-chain triglyceride beverage, a carbohydrate drink, or a combined MCT-carbo-hydrate mixture. The fastest speed was achieved when the athletes used the MCT-carbohydrate blend. The worst performance was associated with sport drinks containing MCT alone (without carbohydrate). Therefore, to gain significant increases in endurance, it is generally recommended that an athlete consume at least 50 grams of MCTs per day in combination with some carbohydrates. However, dosages exceeding 30 grams often cause gastrointestinal upset, which can diminish an athlete’s performance.

MCT products available in the market may have high water content or contain unwanted ingredients. Therefore, athletes should buy MCT-only products, and mix a small amount into carbohydrate soft drinks. Alternatively, they can purchase premixed MCT sport drinks, such as a brand known as SUCCEED.

Thermogenic Diet

MCTs are popular among body builders because they help reduce carbohydrate intake, while allowing them ready access to energy whenever they need it. MCTs also have muscle-sparing effects. As a result, they can build muscles while reducing fats. However, this does not mean that these athletes will become healthier, because an improvement in body physique does not always correlate with higher fitness levels.

Pre-Competition Diet

Compared to carbohydrates, medium-chain triglycerides are a better and more efficient source of quick energy. They help conserve lean body mass because they prevent muscle proteins from being used as energy. Therefore, some athletes load up on medium-chain triglycerides the night before a competition. However, MCT intake should be raised gradually to allow the body to adapt to increasing MCT consumption. If MCT consumption abruptly increases, incomplete MCT metabolism may occur, producing lactic acid in the body and a rapid rise of ketones in the blood, which can make the person ill.

Weight-Loss Diet

Studies have shown that MCT may increase metabolism, which is the rate that the body burns fat. It is believed that sustained increases in metabolic rate cause the body to burn more fat, resulting in weight loss. However, for any kind of meaningful weight loss, a person would have to consume more than 50% of total daily caloric intake in the form of medium-chain triglycerides.

Treatment of Seizures

A ketogenic diet, or diet containing mostly medium-chain triglycerides, offers hope for those who have seizures that cannot be controlled by currently available drugs. Excessive consumption of MCTs produces ketones in the body; therefore, this type of diet is called a ketogenic diet. It has proven effective for some epileptic patients.

Nutritional Supplements

MCTs are the preferred forms of fat for many patients with fat malabsorption problems. Many diseases cause poor fat absorption. For instance, patients with pancreatic insufficiency do not have enough pancreatic enzymes to break down LCTs. In children with cystic fibrosis, thick mucus blocks the enzymes that assist in digestion. Another fat absorption condition is short-bowel syndrome, in which parts of the bowel have been removed due to disease. Stressed or critically ill patients also have a decreased ability to digest LCTs. Unlike LCTs, medium-chain triglycerides are easily absorbed by patients with malabsorption conditions. These patients benefit most from oral preparations that contain MCTs as the primary source of fat (up to 85% of fat caloric intake). Several scientific studies have shown MCT to be effective in treating fat malabsorbtion, chronic diarrhea, and weight loss in patients with Acquired Immune Deficiency Syndrome (AIDS).

Many MCT products can be found in local health food stores or ordered through pharmacies. Before purchasing these products, patients should consult their doctors or registered dietitians for advice concerning appropriate dosage and use. MCT oil is not used for cooking. However, it can be used for tube feeding in critically ill patients. Healthy people may take it orally, by itself or mixed with water, juice, ice cream, or pudding.

Preparations

Available medium-chain triglyceride products include:

• MCT oil
• sports drinks
• energy bars
• meal replacement beverages

Precautions

• People with hepatic encephalopathy, brain and nervous system damage that occurs as a complication of liver disorders, should not take MCT.
• High consumption of medium-chain triglycerides can cause abdominal pain, cramps, and diarrhea.
• Long-term high-level MCT consumption is associated with increased risk of heart disease and other conditions. Even moderate consumption of medium-chain triglycerides can increase cholesterol and triglyceride levels. Therefore, no more than 10% of a person’s diet should come from MCTs.
• Diabetic athletes and those with liver disease should not use MCT products.
• MCT oil should not completely replace all dietary fats, as this would result in a deficiency of other fatty acids—essential fatty acids—that the human body needs from food sources. To avoid essential fatty acid deficiencies, a person should also include omega-3 and omega-6 fatty acids in their diets. Good sources of omega-3 include fish, fish oils, or flaxseed oil. Omega-6 fatty acids are often found in vegetable oils and evening primrose oil. The omega-3 fats have several additional health benefits, such as alleviating inflammation and protecting the body against heart disease.
• A person should not take medium-chain triglyceride products on an empty stomach, as this may cause gastric upset.
• MCT oil is not for cooking. It is usually consumed in its uncooked form as sport bars, or mixed with a carbohydrate drink, protein shake, or other products.
• MCT oil leaches into plastic bags and containers. Therefore, non-plastic containers should be used for MCT oil storage.

Side Effects

There are a few adverse effects associated with MCT use. Eating foods containing medium-chain triglycerides on an empty stomach often causes gastrointestinal upset. Regular consumption of MCTs may increase cholesterol and triglyceride blood levels.

Interactions

There have been no reported interactions between MCTs and other drugs.

Resources

Books

Antonio, Jose, and Jeffery Stout. Supplements for Endurance Athletes. Champaign, IL: Human Kinetics, 2002.

Ivy, John, and Robert Portman. The Performance Zone: Your Nutrition Action Plan for Greater Endurance and Sports Performance (Teen Health Series). North Bergen, NJ: Basic Health Publications, Inc., 2004.

Ryan, Monique. Sports Nutrition for Endurance Athletes. Boulder, CO: Velo Press, 2002.

Stapstrom, Carl E. Epilepsy and the Ketogenic Diet: Clinical Implementation & the Scientific Basis. Totowa, NJ: Humana Press, 2004.

Periodicals

(No author). “Medium-Chain Triglycerides May Help Promote Weight Loss.” Obesity, Fitness & Wellness Week (March 29, 2003): 5.

(No author). “Medium Chain Triglycerides.” Alternative Medicine Review (October 2002): 418–20.

Donnell, S.C., et al. “The Metabolic Response to Intravenous Medium-Chain Triglycerides in Infants After Surgery.” Alternative Medicine Review (February 2003): 94.

St-Onge, M.P., and P.J. Jones. “Physiological Effects of Medium-Chain Triglycerides: Potential Agents in the Prevention of Obesity.” Alternative Medicine Review (June 2002): 260.

St-Onge, M.P., et al. “Medium-Chain Triglycerides Increase Energy Expenditure and Decrease Adiposity in Overweight Men.” Obesity Research (March 2003): 395-402.

Organizations

American Dietetic Association (ADA) Consumer Information Hotline. (800)366-1655..

Other

Klein, Samuel. “Lipid Metabolism During Exercise.” Health-World Online. Abstract from NIH Workshop: The Role of Dietary Supplements for Physically Active People. .

PDRhealth.com article. “Medium-Chain Triglycerides.” .

[Article by: Mai Tran]

Tags: triathlon results, triathlon gear

After all, dietary fat is necessary [...]]]> An extremely informative article on the vital need for increasing Omega-3 oils in our otherwise highly deficient modern diets, as well as some interesting benefits for endurance athletes when consuming medium-chain fats in sports drinks. Mike.

Fat is necessary to absorb key vitamins and assists carbohydrate in providing you with energy

After all, dietary fat is necessary to absorb key vitamins such as A, D, E, and K. And athletes involved in heavy training often need moderate amounts of fat in their diets just to satisfy their monumental daily caloric needs. Fat also assists carbohydrate in providing the fuel needed for endurance performances

However, not all fats are the same. Athletes can choose from saturated, monounsaturated, and polyunsaturated fats, and there are various kinds of polyunsaturates. There’s also the possibility of choosing between medium-chain fats, such as those found in many dairy products, and long-chain lipids, like those found in meats and plants.

Are certain forms of fat best for maximizing exercise capacity?And which type of fat is superior for your overall health?

Those two key questions have been debated vigorously during the past decade. Lately, the popular press has trumpeted the merits of monounsaturated fat for improved cardiovascular health, and athletic publications have put forth the proposition that medium-chain fats might increase performance under certain circumstances (basically, during ultra-endurance competitions).

Health-conscious athletes have been trying to reduce the amount of saturated fat and cholesterol in their diets, often substituting polyunsaturated fats such as corn oil or mono-unsaturated fats like olive oil for animal fat, and many ultra-athletes have initiated the practice of consuming medium-chain fats during their events

Does low-cholesterol drive you mad?

However, the general move in the athletic world toward lower-cholesterol diets isn’t without potential problems, because some research has linked low-cholesterol diets with increased rates of depression and suicide. Even more surprisingly, carefully documented research has determined that cholesterol levels are often below normal in habitually violent and impulsive homicidal criminals. Among adolescents, individuals who have an ‘aggressive conduct disorder with an attention deficit problem’ frequently have below-normal cholesterol concentrations

Why would cholesterol-poor diets and/or low blood cholesterol levels put people into a funk? The American Meat Council claims that the taste of animal flesh is a basic human need which – if denied – leads to aggressive behavior and poor mental health, but their explanation, while short and sweet, is flavored with a sour hint of conflict of interest. A decent biochemical explanation for the connection between low cholesterol and depression is that cholesterol, in spite of its reputation as the ‘bad boy’ of human nutrition, actually plays some key roles inside the body. One of its important functions is to maintain the integrity of brain-cell membranes

Preserving the integrity of brain cells is a good idea, since keeping the membranes intact keeps the cells working – and the individual possessing those cells alive. Often forgotten, however, is the fact that brain-cell membranes do more than keep the internal contents of brain cells from leaking out; they also contain ‘receptors’ for key chemical messengers in the brain. The receptors are simply attachment points for these messengers, which permit cell-to-cell communication, and cholesterol helps to keep those attachment points functioning properly and the cells communicating normally with each other

One of the key messengers is a chemical called serotonin, which exerts a calming, anti-depressant effect in the human brain. Serotonin levels are low in many individuals suffering from depression, and extremely violent military men and impulsive arsonists have been shown to have impaired serotonin output. Prozac, a widely-prescribed anti-depressant drug, acts to increase brain serotonin concentrations and improve mood and self-confidence. Overall, augmented levels of serotonin seem to be linked with better mental health, while low levels may be correlated with depression, violence, and the impulse to burn down your neighbour’s house

In theory, if your diet were too low in cholesterol, you would have poorly structured brain-cell membranes, reduced numbers of receptors, and therefore brain cells which have a lower capacity to react well with serotonin. In short, you’d get depressed. This link between cholesterol, serotonin, and overall brain function explains why many researchers believe that low-cholesterol diets – such as the ones followed by many athletes – can increase the risk of the blues

But the Finns say no

Sounds good so far, and several studies have linked low cholesterol with depression, but a recent study completed in Finland reached the opposite conclusion. Finnish people who began to consume lower-cholesterol diets actually had reduced rates of depression. In addition, a key problem with the low-cholesterol, high-depression hypothesis is that it means that individuals who are depressed should have lower rates of heart disease (their low cholesterol would downgrade the risk of heart maladies). In reality, depressed people often have higher frequencies of heart troubles

So what’s the real relationship between low-cholesterol diets and depression? Why were Finns with less cholesterol delighted instead of dispirited? The answer might be found by looking at the actions of a fat called DHA (docosahexaenoic acid), which is a polyunsaturated, ‘omega-3′ fat. You may recall that ‘omega-3′ fats shone brilliantly on the nutritional stage several years ago, when research suggested that they might help prevent heart attacks and strokes. Don’t be put off by the term ‘omega-3′. To understand what the term ‘omega-3′ actually means, remember that molecules of fat contain fatty acids, which are long strings of carbon atoms to which hydrogen atoms are attached. Usually, each carbon atom has two hydrogens attached, but sometimes a hydrogen is missing and the carbon is ‘double-bonded’ to an adjacent carbon. The term ‘omega-3′ simply means that the first double bond between carbon atoms is three carbons away from one end of a fatty acid

Certain sources of fat – such as fish oils – are fairly high in omega-3 fats, whereas more commonly used fats like vegetable oils have a preponderance of ‘omega-6′ fats, with the first double bond six carbons away from the end. For now, the only thing you need to remember is that the omega-3 and omega-6 fats are different chemically and play different roles in your body

As mentioned, DHA is an omega-3 fat. It’s critical for our story because – like cholesterol – DHA plays a significant role in the construction of brain-cell membranes. As researchers Joseph R. Hibbeln and Norman Salem of the National Institute of Alcohol Abuse and Alcoholism in Rockville, Maryland, point out, people who attempt to bring down their cholesterol levels often do so by reducing the total amount of fat in their diets. This lowers the amount of DHA they’re taking in – and therefore the amount of DHA which reaches their brains to build brain-cell membranes. In theory, these people are more likely to get depressed, since their brains are low in DHA. This chain of events would make it look as though low cholesterol were causing depression, even though the real culprit was inadequate DHA

Should you fry in fish oil?

In the Finnish study, in which diminished cholesterol intake led to lower – not higher – rates of depression, the study participants added a twist to the usual story: they didn’t lower their cholesterol and saturated-fat intake the usual way – by slipping corn and soybean oil into their pots instead of butter – but primarily by eating increased amounts of fish and less beef. Fish is lower in fat than beef and also turns out to be a rich source of DHA, which may explain why the Finns didn’t get depressed as their cholesterol levels dropped. In contrast, corn oil, which many people turn to as an alternative to saturated fat, is low in DHA. It could be that the corn-oil types are getting depressed in droves because of too-little DHA. Does this mean you should fry in fish oil rather than corn or soybean oil?

Maybe so, because Hibbeln and Salem firmly propose that it’s the reduction in DHA and other omega-3 fats – not the decrease in cholesterol intake – which is the source of the depression problem. They suggest that the direct link between coronary artery disease and depression is simple to explain: the high saturated-fat diets of many people lead to clogged arteries, and the lack of omega-3 unsaturated fat in the saturated-fat regimen raises the risk of depression. Shifting these saturated-fat eaters over to corn, soybean, or safflower oil will keep the arteries cleaner but won’t help the mental side of things, in Hibbeln and Salem’s view, because those vegetable oils are low in omega-3s. Hibbeln and Salem even venture into theories of criminality, proposing that violent, impulsive behavior is associated with low levels of omega-3 fats and high quantities of the more popular omega-6 fats and saturated lipids

While the latter claim may seem extreme, it’s backed up by some pretty decent research. For example, several years ago researchers at the Helsinki University Central Hospital checked out 34 habitually violent, impulsive male criminals. Eleven of these individuals had committed more than two violent crimes and four were impulsive arsonists. When blood samples from the 34 were compared with those from 16 healthy men from the University staff, it was found that the criminals had significantly higher levels of omega-6 fatty acids and appreciably lower quantities of one of the key omega-3 fats, DHA. In addition, men who had attempted suicide had roughly 20 per cent high omega-6 concentrations, compared to men who had never tried to take their own lives. Of course, we can’t say conclusively that low DHA drove the men to crime or suicide: correlations between variables don’t mean that one is the driving force behind the other

Is the future in the past?

However, another interesting observation is that the prevalence of depression in the industrialized world has increased fairly dramatically in the past 100 years or so. In fact, since 1900 each group of people born within a 10-year period has had a higher risk of depression, compared to those born during the previous decade. If you were born between 1950 and 1960, for example, your depression risk is significantly greater, compared to someone born between 1940 and 1950, and appreciably higher than the risk incurred by someone born before 1940. True, the stresses of modern life may contribute to this effect, but it’s also true that this century has seen a fairly dramatic increase in human consumption of omega-6 fatty acids, along with a fall in the intake of omega-3 lipids

There are a couple of reasons for this critical dietary swing. First, the nature of agriculture has shifted, so that just a few plant species (primarily corn and soybeans) are utilized as sources of fatty acids. These plants are relatively poor in omega-3 fats. In contrast, during evolutionary history, humans – especially in hunter-gatherer cultures – tended to eat wide varieties of vegetables and therefore took in products with higher amount of omega-3s. Second, commercial livestock are high in overall fat content but pretty deficient in omega-3 fats. For example, a side of beef coming from the cattle pen to your plate usually has a body-fat content of around 30 per cent, similar to a sedentary human, and virtually no omega-3 fat at all. When you eat the thing, you’re swamping your body with saturated and omega-6 fat and neglecting omega-3 fats totally

In contrast, the free-range and wild animals (including deer, bison, horses, mammoths, and various grazing herbivores) which made up a larger portion of the human diet over the past million years or so were much richer in omega-3s and lower in overall fat. For example, a free-living African herbivore has a body-fat level of just 4 per cent, like the best human endurance athlete, with a good deal of this fat as omega-3

The result of the change in agricultural practices and human eating habits is that the ratio of omega-6 fat to omega-3 fat in the human diet has changed drastically. In fact, the average ratio of omega-6/omega 3 in the modern diet is now estimated to be somewhere between 10/1 and 25/1, a huge change from the ratio which prevailed during two million years of human evolution, which was probably about one to one! The bottom line is that humans are now eating much less omega-3 fat than they did during their long evolutionary history – and perhaps paying the price from a health standpoint

It’s tempting to think that this change in fat intake may be related not only to the modern epidemic of depression but also to the current rampage of coronary artery disease. Critics of the notion that cardiovascular disease is a new thing contend that coronary artery maladies weren’t a big health problem for paleolithic humans because they simply didn’t live long enough to get into trouble, but it’s interesting to note that very young Britons and Americans (age 20 or less) often already show signs of atherosclerosis, whereas currently existing hunter-gatherer tribes in Africa and other parts of the world, with their increased intakes of omega-3 fats, do not. This is in spite of the fact that hunter-gatherers may eat fair amounts of cholesterol, 500-600mg per day by some estimates, about double the amount recommended by the U.S. Senate Select Committee on Nutrition. Individuals from such cultures who reach the age of 60 or more often exhibit little evidence of coronary disease, despite their ample cholesterol intakes

Why Japanese fishermen always smile

Should you consider stepping up your omega-3 intake to improve your mental state? One way to boost omega-3 in your diet would be to eat more fish, and it’s interesting to note that fish-eating people have considerably lower rates of depression, compared to beef- and pork-eating ones. For example, the incidence of depression in North America and Europe is about 10 times greater than the rate in Taiwan, where the people eat large amounts of fish. Studies carried out in the United States reveal that about 4.4 per cent of males and 8.7 per cent of females in New Haven, Connecticut suffer from depression. The rates of depression are 2.3 per cent for males and 4.9 per cent for females in Baltimore, and 2.5 per cent and 8.1 per cent in St. Louis. In contrast, rates of depression in Hong Kong, where people eat huge quantities of fish are about .71 per cent and 1.30 per cent for males and females, respectively. In Japan, where fish consumption is even higher, depression rates are .35 per cent for males and .46 per cent for females, and in some Japanese fishing villages rates of depression have been pegged at zero!

If low omega-3 consumption contributes to both depression and coronary artery disease, then depression and atherosclerosis should be positively correlated, the exact reverse of the hypothesis that depression, as a consequence of low cholesterol, protects against heart disease. In fact, 30 years of research have shown that depression is a good PREDICTOR of heart disease AND poor survival after a heart attack (depression as a REACTION to heart disease was separated from the analysis)

There has not been a lot of experimental work looking at the direct effects of omega-3 fats on depression, but the work that has been done has been favourable. In one study carried out with 494 elderly people, treatment with ‘bovine cortex’, or cow brains, which are a rich source of omega-3s, significantly improved mood and reduced symptoms of withdrawal and apathy, compared to treatment with corn oil (forget about the current scare over BSE)

A digression on breast-feeding

Since omega-3s are so critical for brain function, it’s not surprising that the quantity of omega-3s in infants’ diets can have a significant impact on brain development. In an important study which com-menced in Cambridge, Ipswich, Kings Lynn, Norwich, and Sheffield in 1982 and 1983, investigators kept track of 210 babies who received mother’s milk and 90 babies who were fed only formula. Mother’s milk is an excellent source of omega-3 fat, while formula contains none

At the age of 18 months, developmental scores were obtained for all 300 toddlers, and at the ages of seven to eight, IQ was assessed in the children using the Weschler Intelligence Scale for Children. Developmental scores were higher at 18 months, and IQ was greater at seven to eight years in the children fed breast milk. In fact, IQ scores were eight to 10 points higher in the breast milk-fed kids!

The research team, a group of distinguished British paediatricians, was able to remove most of the problems associated with this kind of research. For example, the breast-fed children received mother’s milk through a tube, eliminating the likelihood that the close bond between mother and child associated with suckling had provided the IQ bonus. And even when the higher social status and educational backgrounds of the mothers who chose to breast feed were adjusted for statistically, the intelligence advantage associated with breast-milk intake remained

Critics have contended that choosing to provide breast milk is an indicator of the tenaciousness of a mother, and that this tenaciousness carries over into the nurturing provided to the child, boosting IQ. However, mothers who chose to furnish breast milk but were then unable to produce milk had kids with IQs similar to those of kids whose mothers chose to dish out formula. There was simply something special in mother’s milk! Overall, getting breast milk raised IQ by about eight points, while higher educational status for the mother nudged IQ up by just two points. Being female rather than male lifted IQ by four points, so mother’s milk was easily the most important IQ-raising factor detected in the study. The researchers also unearthed a ‘dose-response’ relationship between mother’s milk and IQ. Those children who had received more maternal milk were sharper than kids who had imbibed less, particularly with regard to verbal measures of intelligence

What exactly was so good about mother’s milk? The researchers pointed the finger at our old friend DHA, which is not present in infant formula but which occurs in decent concentrations in human breast milk. As the investigators pointed out, DHA is accumulated in large quantities in the developing brain and retina and is crucial for overall mental development

What is the practical meaning of all of this? The addition of fish to your diet several times weekly may decrease your risk of cardiovascular disease and depression. Research suggests that a dietary intake of .5 to 1.0 grams of omega-3 fat per day reduces the risk of cardiovascular death in middle-age men by about 40 per cent, but current actual intake in the United States is only .05 grams daily. If you want to use supplements to obtain more omega-3 fats, experts contend that the supplement should contain high amounts of EPA and DHA but little or no cholesterol or vitamins A and D. Vitamin E should be added to prevent the omega-3s from being oxidized

How omega-3s can affect performance

What about fat type and performance? If you’re already involved in regular training, the effects of omega-3 fats may not be so direct and immediate that ingesting increased quantities of them for six weeks would improve your race times or lift your VO2max.. However, it’s obvious that the less depressed you are, the higher will be your motivation and drive to succeed as an athlete, so inclusion of omega-3 fats in your diet may be favourable to performance from a mental standpoint

It’s also possible that omega-3s might improve performance by upgrading blood flow to the muscles. In one study, blood flow to leg muscles of human subjects was restricted by the application of tourniquets. Some subjects then received a placebo, while others received an infusion of ‘prostaglandin E1′, a chemical which is produced by omega-3 fatty acids. Blood flow was 2.5 times greater in individuals who received E1. Increased blood flow would help endurance athletes by transporting increased oxygen and fuel to muscles and perhaps by improving the buffering of acids produced during intense exercise.

The extra oxygen might raise VO2max, and there’s also some evidence that omega-3 fats could reduce muscle inflammation following overly strenuous workouts

Only one peer-reviewed piece of research has actually looked at whether omega-3 fats can bolster exercise capacity. In that study, carried out at Western Washington University, 32 healthy young males were divided into four groups. One group acted as controls, a second group ingested four grams of omega-3 fat per day, a third group undertook a vigorous aerobic exercise programme, and a fourth group participated in the same exercise programme while taking the omega-3 supplements

After 10 weeks, the non-exercising group which consumed omega-3s was better off than the non-exercised control group without the omegas. Their average VO2max had risen by 11 per cent, against just 4.5 per cent for the controls. In other words, starting to supplement one’s diet with omega-3s is a bit like going on a moderate exercise programme; one’s ability to utilize oxygen seems to increase

However, both exercising groups, the one with omega-3s and the one without, broadened VO2max by about the same amount, 20 per cent, indicating no additional benefit of omega-3 fats when an exercise programme is undertaken. It would be interesting to see this same study carried out for a longer period of time or with a more experienced group of athletes. Perhaps under those conditions, omega-3s could induce some subtle, positive effects

What about medium-chain fats?

Broadening our focus from omega-3 fatty acids to fats in general, there has been some indication that ‘medium-chain’ fats are better for performance than the usual ‘long-chain’ lipids (medium-chain fats have only 10 to 14 carbons in their fatty-acid chains, while long-chain lipids have about 18 to 22).

The advantage of medium-chains may be due to several factors: medium-chain triglycerides (MCTs) are absorbed from the digestive system more quickly than regular lipids, and scientific studies have linked MCTs with an increased metabolism of body fat, preservation of muscle tissue, and significant increases in metabolic rate.

To make themselves look more attractive to finicky humans, MCTs don’t allow themselves to be stored very easily as body fat, and some research has indicated that MCTs are not likely to end up in the fatty deposits which tend to clog the inside walls of your coronary arteries

To make matters even more interesting, exercise scientists have long speculated that MCTs might promote improved endurance performances, primarily because MCTs can slip into the ‘mitochondria’ inside muscle cells much more readily than regular fats. Since muscles create most of the energy they need by breaking down fat and carbohydrate inside their mitochondria, MCTs’ ability to enter the mitochondria quickly should increase energy production and help to conserve muscles’ most precious fuel – glycogen

Until now, however, MCTs’ capacity to enhance exercise was speculative, but a recent study at the University of Cape Town demonstrates that MCTs can indeed improve performances – in certain situations. In the South African study, six experienced cyclists performed the same exercise test on three separate days.

The test consisted of two hours of easy pedalling at just 60% VO2max (about 73 per cent of maximal heart rate), closely followed by a 40-kilometre time trial completed as quickly as possible. During the three tests, the athletes consumed either a 10 per cent carbohydrate solution, a 4.3 per cent MCT beverage, or a drink which contained both 10 per cent carbos AND 4.3 percent MCTs. In all cases, the subjects consumed 400 ml (14 ounces) of drink at the beginning of the test and then 100 ml (3.4 ounces, or three to four normal swallows) every 10 minutes thereafter

The carbohydrate PLUS MCT drink produced the best performances during the 40-K time trial. With carbo plus MCT, cyclists needed just 65 minutes to complete the ride, versus 66:45 with carbohydrate alone and a sluggish 72:08 with only MCTs

Why did adding MCT to the carbohydrate sports drink enhance performance? Basically, MCTs decreased glycogen depletion in the cyclists’ leg muscles during the first two hours of the tests; the MCTs simply replaced glycogen as an energy source during those first two hours. As a result, when the cyclists pedalled along furiously during the 40-K trial, carbo-MCT athletes had more glycogen available to sustain their intense efforts

Why MCTs alone don’t work

It’s important to bear in mind that the MCTs had to be ADDED to carbohydrate in order to shore up performance; the MCT-only drink produced terrible results.

Owen Anderson

Don’t miss out on hundreds of vital training workouts and cutting edge research.
Trial Peak Performance today for just $9.97.

Tags: sprint triathlon, duathlon

There’s more to protein nutrition than just eating the optimum amount; the timing of consumption and the type [...]]]> A comprehensive and well researched article for those who want to optimise their nutrition to maximise performance which could give them the edge over their competition. Mike.

There is more to protein intake than simply eating the right amount

There’s more to protein nutrition than just eating the optimum amount; the timing of consumption and the type of protein selected can both impact on nitrogen balance; and there are a number of nutritional ‘co-factors’ that are either essential or useful in promoting optimum protein metabolism within the body.

This is especially true where carbohydrate is concerned, because building or even maintaining lean tissue mass is an ‘energy-intensive’ process. Increasing protein intake at the expense of carbohydrate can be a bad strategy for athletes engaged in heavy training, because without sufficient carbohydrate the body simply switches to other fuels for energy, and amino acids from protein (particularly the branched chain amino acids, leucine, isoleucine and valine) provide a ready source of energy!

Muscle tissue is a relatively rich source of branched chain amino acids (BCAAs), and tends to undergo breakdown during periods of highenergy demand, when carbohydrate and/or the amino acid pool becomes depleted. Furthermore, carbohydrates stimulate the release of insulin, a highly anabolic hormone, which helps to drive both glucose and amino acids into muscle cells. Any athlete seeking to optimise his or her protein metabolism should therefore ensure a carbohydrate intake commensurate with training volume.

Protein-carbohydrate mixes

The role of carbohydrate in enhancing endurance during long events and accelerating post- exercise recovery is undisputed, and new research (highlighted in PP 194, March 2004) indicates that carbohydrate feeding before and during high intensity exercise can limit the amount of stress hormone release, thereby reducing the risk of post-exercise immune suppression. However, research suggests that protein has a role to play, too. A study on resistance training examined hormonal responses to water, carbohydrate, protein or a carbohydrate/protein mix, given immediately and then two hours after a training session. As expected, those fed the carbohydrate and carbohydrate-plus-protein mix drinks showed an increased insulin response.

However, those fed the carbohydrate-protein mix also showed a modest but significant increase in growth hormone levels, suggesting that protein combined with carbohydrate following resistance training may create a more favourable hormonal environment for muscle growth.

Post-exercise protein feeding seems to be beneficial for endurance athletes also. In a study on 40 swimmers given either water or water-plusglucose during training sessions and then either water, sucrose or a sucrose-plus-milk protein mix after training, the subjects receiving the posttraining sucrose-protein mix exhibited lower levels of creatine phosphokinase (a marker of muscle damage) than the others. Moreover, creatine phosphokinase levels returned to baseline levels more rapidly in this group, indicating that the ingestion of protein with carbohydrate accelerates recovery.

A study on ultra-endurance athletes, published just a few months ago, showed that a carbohydrate-protein mix maintained a positive nitrogen balance during and after a six-hour training session (five hours of cycling and one hour of running), while a straight carbohydrate drink did not.

The consensus of scientific opinion now is that, following intense exercise, athletes should ingest a carbohydrate and protein mix (around 1 gram per kg of body mass of carbohydrate and 0.5g per kg of protein) within 30 min of completing exercise, as well as consuming a high-carbohydrate meal within two hours. This nutritional strategy has been found to accelerate glycogen resynthesis as well as promoting a more anabolic hormonal profile that may hasten recovery.

Research carried out over a decade ago indicated that ingesting a light carbohydrate/ protein snack 30-60 minutes before exercise is also beneficial. In these studies it was shown that 50g of carbohydrate and 5-10g of protein, taken before a training session, could increase carbohydrate availability towards the end of an intense exercise bout and also enhance the availability of amino acids to muscles, thereby decreasing exercise-induced catabolism (breakdown) of protein.

This research appears to be backed up by a very recent study carried out on 15 trained cyclists, who cycled to exhaustion on two rides 12-15 hours apart, the first at 75% and the second at 85% of VO₂max. During the test, riders were split into two groups and given either a 7.3% carbohydrate drink (1.8ml per kg every 15 minutes), or the same drink with protein added at 1.8%. After 7-14 days, the test was repeated and the drink protocol reversed.

The results showed that riders taking the carbohydrate-plus-protein rode for 29% longer than the carbohydrate-only group during the first (75% VO₂max) ride and 40% longer during the second (85% VO₂max) ride! Furthermore, peak levels of creatine phosphokinase were 83% lower when carbohydrate plus protein was taken. Since the carbohydrate plus protein drink contained 25% more calories overall, further studies are needed to see how much of this effect is due to higher energy intake. However, it seems reasonable to assume that a carbohydrate-protein drink taken during training provides for increased protein concentration outside the cell, which can potentially enhance protein synthesis and repair.

The concept of different glycaemic indexes (the rate at which digested carbohydrate is released into the bloodstream as glucose) for different carbohydrates is now well accepted. However, different proteins display different rates of breakdown into their amino acid building block constituents, and hence uptake into the body.

A study into whey protein and casein (two types of protein supplements that are popular with athletes and bodybuilders) examined the speed at which one of the amino acids (leucine) appeared in the bloodstream after ingestion of a meal of each kind of protein (containing identical amounts of leucine). The researchers found that whey led to a dramatic but short-term increase in plasma amino acids, while casein induced a prolonged plateau of moderately increased levels.

They concluded that the differences were probably explained by the slower gastric emptying of casein. Whey protein is a soluble protein whereas casein clots into the stomach, so delaying its gastric emptying. Likewise, soy protein appears to be digested more rapidly than milk protein, resulting in a higher but more transient peak of plasma amino acids.

The implications are obvious: an athlete seeking to supply a post-training or mid-training boost to the amino acid blood pool would be best advised to consume a fast-release protein, such as whey or soy. However, when a prolonged period of recovery is in store (eg at bedtime) a slowerreleasing casein protein drink, such as milk, would be better. Another implication of this study is that, providing a meal or drink supplies the same quantity of the essential amino acids, one type of protein is not necessarily ‘better’ than another. Of more importance is that its release rate is matched to the timing of ingestion.

The situation also appears to be complicated by age. A recent study, which looked at the effects of protein retention in young men (mean age 25 years) fed protein meals containing either slow-releasing casein proteins or rapid-releasing whey proteins, found a greater retention (ie uptake into muscles) after casein. However, when the same researchers studied protein retention in elderly subjects (mean age 72 years), their findings were reversed, with whey protein producing a significantly higher uptake of amino acids than casein.

The researchers surmised that amino acid availability may limit muscle synthesis in older subjects, and that the higher amino acid peaks produced by whey prevented this from happening. The implication seems to be that ingesting fast-releasing proteins mid- or postexercise may be more important for older athletes than their more youthful counterparts.

‘Free form’ amino acids

The process of digestion releases the amino acid building blocks from ingested protein. However, as we’ve seen, this release rate is variable and the process of digestion itself actually consumes energy. This has prompted some investigators to ask whether the use of ‘free form’ amino acids before, during or after training could be a rapid method of providing athletes with optimum amounts of amino acids exactly when they’re needed.

Particular interest has been shown in the branched chain amino acids (BCAAs), which are readily oxidised for energy and therefore in greater demand when energy output is high. In theory, BCAA supplementation might help to minimise protein degradation, thereby leading to greater gains in fat-free mass, or at least minimise lean tissue loss when training volumes are high.

BCAAs and body composition

There is some evidence to support this hypothesis; for example, a study conducted on trekkers at altitude found that taking 10g of BCAAs per day during a 21-day trek increased fat-free mass by approximately 1.5%, while controls on placebo experienced no such change. Meanwhile, another study found that 30 days of BCAA supplementation (14g per day) promoted a significant increase in muscle mass (+1.3%) and grip strength (+8.1%) in untrained subjects.

These findings suggest that BCAA supplementation may have some impact on body composition. Moreover, some recent evidence suggests that BCAA supplementation can decrease exercise-induced protein degradation and/or muscle enzyme release (an indicator of muscle damage), possibly by promoting an anticatabolic hormonal profile⁽. However, despite the persuasive rationale, the effects of BCAA supplementation on short- and long-term exercise performance are somewhat mixed, with some studies suggesting an improvement and others showing no effect. More research is needed, therefore, before firm conclusions can be drawn.

Having said that, there is good evidence that BCAAs administered during training can reduce the perception of fatigue, while improving mood and cognitive performance. A study on seven male endurance-trained cyclists with depleted glycogen stores examined the effects of BCAA supplementation (versus placebo) on mental fatigue and perceived exertion. The subjects exercised at a work rate corresponding to approximately 70% VO₂max for 60 minutes, followed by another 20 minutes of maximal exercise.

During the 60-minute section, the subjects’ ratings of perceived exertion were 7% lower and mental fatigue 15% lower when they were given BCAAs. In addition, cognitive performance in the ‘Stroops Colour Word Test’ performed after exercise was improved when BCAAs had been ingested during exercise. Interestingly, however, there was no difference in physical performance in the final 20-minute segment of the ride between the placebo and BCAA groups; the amount of work performed during this section was the same regardless of which supplement was taken.

These findings on BCAA supplementation, mental fatigue and perceived exertion were replicated in a study on runners given carbohydrate-plus-BCAA drinks or carbohydrateonly drinks (placebo) during a 30k cross-country run. Subjects on BCAAs improved their postexercise performance in the above-mentioned Stroops test by an average of 3-7% compared with those on placebo. The BCAA group also maintained their performance in two more complex mental tasks (shape rotation and figure identification) after exercise, while the placebo group showed a 25% and 15% reduction respectively in these tasks.

Researchers believe that this cognitive effect may be due to the ability of BCAAs to compete with and therefore reduce the uptake of another amino acid, tryptophan, across the blood-brain barrier and into the brain. Tryptophan is the precursor to a brain neurotransmitter called 5- hydroxytryptamine (5-HT – more commonly known as serotonin), which is involved in fatigue and sleep and is believed to contribute to the development of central/mental fatigue during and after sustained exercise. During exercise, the concentration of tryptophan in the blood relative to other neutral amino acids seems to rise. But supplementing with BCAAs seems to help block this effect, which would, in turn, reduce levels of 5- HT in the brain.

Essential amino acids

The BCAAs comprise just three of the nine essential amino acids (EAAs), the other six being histidine, lysine, methionine, phenylalanine, threonine and tryptophan. As mentioned, essential amino acids have to be obtained from the diet because they can’t be synthesised in the body from other amino acids. Although the six ‘straight chain’ EAAs are not so readily utilised as fuel, some researchers believe that giving all nine EAAs in a free form (ie as a mix of separate amino acids, not as protein), and in ratios that reflect the amino acid composition of muscle protein, is more beneficial for muscle protein synthesis than giving BCAAs alone.

In recent studies, scientists in Texas have found that ingesting 3-6g of EAAs before and/or after exercise stimulates protein synthesis. Moreover, this stimulation appeared to increase in a dose-dependent manner until plasma EAA concentrations are doubled, and was maximised when EAAs were administered to maintain this doubled concentration over a three-hour period. Adding carbohydrate seemed to enhance this protein synthesis, probably through the anabolic effect of insulin.

Although there has been very little research on EAA ingestion by athletes, studies on resistance training in healthy adults seem to confirm the potential benefits of EAAs; for example, muscle protein synthesis was increased 3.5-fold when 6g of a mixture of EAAs was given along with 35g of carbohydrate after resistance exercise.

In another study, three men and three women resistance trained on three separate occasions and then consumed, in random order, one of the following:

• a 1 litre solution of mixed amino acids containing both essential and nonessential amino acids (40g);
• a solution containing only essential amino acids (40g);
• placebo.

Net muscle protein balance was negative after ingesting placebo but positive to a similar magnitude for both the mixed and essential amino acid drinks. The researchers concluded that: ‘it does not appear necessary to include nonessential amino acids in a formulation designed to elicit an anabolic response from muscle after exercise’.

A comprehensive protein strategy

Given the above findings, what reasonable steps can an athlete take to optimise his or her protein nutrition? Below is a ‘protein checklist’, which crystallises these findings into dietary recommendations:

• Ensure an adequate intake of dietary protein – ie a minimum of 1.5g of high-quality protein per kg of body weight per day. Power/strength athletes, or those engaged in intense training, should consider increasing this to 2g per kg per day;
• Ingest protein-carbohydrate drinks after exercise rather than protein alone. Ideally, consume a drink made up of about 1g per kg of carbohydrate and 0.5g per kg of protein within 30 minutes of training, and eat a high-carbohydrate meal within two hours;
• Consume a light pre-exercise snack: 50g of carbohydrate and 5-10g of protein taken before a training session can increase carbohydrate availability towards the end of an intense exercise bout and also increase the availability of amino acids to muscles. However, make sure your snacks are low in fat to allow for rapid gastric emptying!
• Use protein/carbohydrate drinks during very long events: a solution containing 73g carbohydrate and 18g protein per litre, consumed at a rate of 1ml per kg of body weight per minute, may delay the onset of fatigue and reduce muscle damage;
• Consume quick-digesting proteins such as soy and whey immediately after training: this may be especially important for older athletes;
• At other meals, consume a mix of proteins in order to promote a more sustained release of amino acids into the body;
• Adding BCAAs to your normal protein intake may be useful for athletes undergoing prolonged or heavy training, and this may be particularly true for events/sports requiring large amounts of mental agility and motor coordination;
• HMB supplementation, at 3g per day, may be a useful additional strategy for novice athletes, or those returning to training after a layoff;
• Essential amino acid blends taken 1-3 hours after training may promote additional muscle protein synthesis, although this hypothesis is not proven in athletes;
• Don’t forget to ensure that your overall diet is of high quality and as whole and unprocessed as possible: this will ensure adequate intakes of other nutrients essential for protein metabolism, such as zinc and the B vitamins.

Andrew Hamilton

References

1. J Appl Physiol, 2003; 548P, 98
2. J Appl Physiol, 2003; 94:1917-25
3. J Appl Physiol, 1994; 76:839-45
4. Eur J Appl Physiol Occup Physiol, 1992; 63:210-5
5. Am J Physiol Endocrinol Metab 2004; 287:E712- E720
6. Sports Med 1999; 27(2):97-110
7. J Appl Physiol 1992; 72(5):1854-9
8. J Appl Physiol 1997; 83(6):1877- 83
9. J Appl Physiol 1998; 85(4):1544- 55
10. Eur J Appl Physiol Occup Physiol 1992; 64(3):272-7
11. Eur J Appl Physiol Occup Physiol 1991; 63(3-4):210-5
12. Med Sci Sports Exerc, 2004; 7:1233-8
13. Proc Natl Acad Sci USA, 1997; 94:14930-35
14. J Nutr 2003, 133:1308-1315
15. Am J Physiol Endocrinol Metab, 2001; 280:E340- 348
16. J Physiol 2003, 549.2:635-644
17. Eur J Appl Physiol Occup Physiol, 1992; 65(5):394-8
18. Minerva Endocrinol 1995; 20(4):217-23
19. J Sports Med Phys Fitness 2000; 40(3):240-6
20. Acta Physiol Scand 1997; 159(1):41-9
21. Nutrition 1994; 10(5):405-10
22. Metabolism 1992; 41(6):643-8
23. Am J Physiol 1992; 263:E928- E934
24. Nutr Rev 1987; 45:289-298
25. Sports Med 1990; 9, 23-35
26. Med Sci Sports Exerc 2000; 32(12):2109-15
27. Med Sci Sports Exerc 2000; 32(12):2116-9
28. J Appl Physiol 1996; 81(5):2095- 104
29. Nutrition 2000; 16(9):734-9
30. Sports Med 2000; 30(2):105-16
31. Nutr 2000; 130(8):1937-45
32. J Nutr 2001; 131(7):2049-52
33. J Appl Physiol 2000; 89: 1340- 1344
34. Int J Sports Med 1999;20(8):503-9
35. Int J Sport Nutr Exerc Metab 2001;11(3):384-96
36. Strength Cond Res 2003;17(1): 34-9
37. Am J Physiol Endocrinol Metab 2003;284(1): E76-89.
38. J Nutr 2002;132(10):3219 S-24S
39. J Appl Physiol 2000; 88:386-392
40. Am J Physiol Endocrinol Metab 1999; 276:E628- E634

This article was taken from the Peak Performance newsletter, the number one source of sports science, training and research. Click here to access these articles as soon as they are released to maximise your performance

Tags: triathlon, sprint triathlon

Would still like to get down to under 78kg, but will only do that after EC Champs on the 31st January, as the last time I tried that I got sick with ‘flu.

Going to try again as it may not [...]]]> The bathroom scale hit my goal weight of 80kg this morning. 5kg of silly season flab gone!

Would still like to get down to under 78kg, but will only do that after EC Champs on the 31st January, as the last time I tried that I got sick with ‘flu.

Going to try again as it may not have been totally weight related. Let’s see…

Tags: olympic triathlon, triathlon wetsuits

If you’d like to try it, here is my Breakfast Mix (Good Boy Porridge). It’s tasty as well as super-nutritious and my [...]]]> Being a bachelor and non-cook, I have to be quite inventive to produce meals that are quick and easy to prepare, tasty enough to withstand daily repetition, and sufficiently nutritious to meet my training needs.

If you’d like to try it, here is my Breakfast Mix (Good Boy Porridge). It’s tasty as well as super-nutritious and my favourite meal of the day.

Mix well all of the following ingredients into a 5 litre Tupperware container or plastic bucket with lid:-

1.    2 x 500 gram Wheat Free ProNutro (I like banana flavour at the moment).
2.    500 gram Pure Soy Protein (Natures Own Pharmacy – Atrium)
3.    2 Packets ground Magic Seeds (Natures Own Pharmacy – Atrium)
4.    500 gram Sunflower Seeds (Natures Own Pharmacy – Atrium)
5.    500 gram Rolled Oats (Natures Own Pharmacy – Atrium)
6.    200 gram Sesame Seeds (Natures Own Pharmacy – Atrium)

Serving:-

1.    I use 2 heaped 50ml scoops with about 200ml water (or milk if you really must) for desired consistency.
2.    Sweeten to taste preferably with Stevia Powder (Natures Own Pharmacy – Atrium) to avoid sugar.
3    Mix in 1 tablespoon of Flaxseed Oil (or Canola Oil) for Omega 3.
4.    Cover “porridge” with a good layer of plain unsweetened low fat yogurt (I like Nutriday) – about 6 to 8 heaped teaspoons.
5.    Slice one medium banana over the top.
6.    Sprinkle some unsweetened Trumps Cocoa powder over all of it (mainly for the chocolate cravings, but it’s also a good antioxidant).

This mix lasts me a month, and I sometimes have more than one serving a day. It’s high in both protein and fibre so also helps keep one regular.

You could also sweeten the yogurt by sprinkling a little of the Stevia powder over it. Stevia is VERY sweet, and the only naturally occurring sweetener that actually has health benefits!

“Good Boy Porridge” may not be suitable for an early race day meal (but the night before should be good) as the fibre could have you needing to run without a place to go! Just plain Jungle B’fast would then be the better option, but still with the yogurt, banana and cocoa powder. It’s higher carb and low fibre.

Enjoy!

Mike

Tags: duathlon, ironman training

If you can work out a way to boost your muscle glycogen to supra-normal levels, your performances in [...]]]> At last an authoritative no BS article on how to be fully fueled and at your best on the start line for that big race – Mike.

Tags: triathlons, sport triathlon