Sports Supplements – Creatine For Endurance Athletes

Creatine supplements can boost your endurance training without encouraging weight gain

swim endurance - Sports Supplements - Creatine For Endurance Athletes

The correct dose of creatine will improve endurance athletes performance without making them gain weight!

Creatine (methylguanidine-acetic acid) was discovered in 1832, but athletes have been taking it – in hopes of improving their performances – for only the last 10 years. Over that time period, a scientific consensus has emerged that creatine supplementation can indeed increase muscular strength and power and improve performances in relatively short-duration, high-intensity activities. The potential benefits of creatine supplementation for longer-duration, lower-intensity exertion (i. e., for endurance-type athletes) have, however, been hotly debated.

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To get a better insight into this debate, you should understand that muscle cells use creatine to form creatine phosphate, a high-energy compound which can be used to rapidly synthesize ATP, the ‘energy currency’ utilized by all cells in the human body. Whenever a nerve cell fires, a muscle fibre contracts, or a kidney cell actively filters some urine, ATP ‘pays the bills’ (i. e., furnishes the energy needed to carry out the activity).

Creatine phosphate is also a ‘buffer’ which tempers the increase in intramuscular acidity associated with intense exercise; in this role, creatine might help allay the fatigue which can be caused by a drop in muscular pH. Because of these two key actions of creatine (ATP creator and buffer), athletes have become extremely interested in supplementing their diets with this unique compound.

There is no question that creatine supplementation increases the amount of creatine phosphate within muscle cells, sometimes by up to 50 per cent. Research support for creatine has been strong, and PP readers will be aware of a lot of it. Studies going as far back as 1986 have shown that when creatine phosphate concentrations drop within muscle cells, those fibres are unable to exhibit normal force production. In addition, a variety of different scientific investigations have linked creatine supplementation with greater muscular force production and power, as well as higher sprinting speeds, faster cycling velocities, and quicker swimming movements during very high-intensity efforts. As a result, there are few elite power athletes in the world who have not given creatine supplementation a try.

But what about endurance athletes?
In contrast, there’s no question that creatine is less popular with the endurance crowd, compared to the power people (one of creatine’s side effects – weight gain – has helped to minimize its popularity among endurance competitors). Somewhat surprisingly, little creatine research has been carried out with endurance athletes, and the few investigations which have been completed have yielded inconsistent results.

Thus, more work has been needed, and in a relatively new study, researchers at Kingston University in Surrey and the University of Tasmania in Australia looked at the effects of creatine on 16 endurance kayakers who possessed a high level of fitness (VO2max = 67.1 ml/kg.min). All 16 subjects took part in an initial workout which consisted of three work intervals which were completed on a kayak ergometer and which lasted for a duration of 90, 150, and 300 seconds. The athletes completed each interval at the highest-possible intensity and recovered completely (heart rate back to resting level) between intervals (‘The Effects of Creatine Supplementation on High-Intensity Exercise Performance in Elite Performers,’ European Journal of Applied Physiology, vol. 78, pp. 236-240, 1998).

The subjects were then randomly assigned to either a ‘creatine group’ or a placebo group. Creatine-group members took four five-gram doses of creatine monohydrate per day for a total of five days, while placebo-group athletes ingested four five-gram supplements of glucose daily. After five days, both the creatine and glucose athletes repeated the three-interval, max-intensity workout.

There followed a four-week ‘washout period’, during which the subjects took neither the creatine nor the glucose supplements. Research has shown that four weeks is long enough to bring an elevated muscle creatine-phosphate concentration back to ‘normal’. Following the four-week washout, all subjects participated in the three-interval workout yet again. Following this re-test, the previous placebo subjects ingested creatine for five days (4 x 5 grams per day) while the former creatine athletes took the glucose placebo (this is what’s called a ‘crossover’ design). After five days, the athletes tried the three-interval session one last time.

Fatter – but stronger
In just five-days time, the creatine supplements made the athletes gain weight. Creatine supplementers gained on average two kilograms (4.4 pounds), or almost one pound per day during creatine supplementation. Meanwhile, the placebo-subjects’ weights held steady.

bike endurance - Sports Supplements - Creatine For Endurance AthletesCreatine also increased the quality of the athletes’ efforts during the three-interval workouts. During the 90-second interval, the kayakers completed about 16 per cent more work when they had supplemented with creatine, compared to taking the placebo or being in the control condition (at the beginning of the study and after the washout period). During the 150-second interval, the athletes completed 14 per cent more work with creatine, and for the five-minute (300-second) interval the creatine subjects hit 7 per cent more work. Blood-lactate levels were also higher for creatine athletes after the 150- and 300-second intervals, compared to control and placebo subjects. However, this was not a bad thing; it merely reflects the fact that the creatine-supplemented athletes were able to work at a higher intensity (and thus ‘cough up’ a bit more lactate).

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Note that the advantage associated with creatine supplementation became smaller as the duration of the work interval increased. This is not terribly surprising. As work-interval duration increases, the relative amount of the energy which is needed to complete the interval which is actually coming from creatine phosphate decreases, as the creation of ATP from the breakdown of carbohydrate (rather than from the transfer of a phosphate group from creatine phosphate) becomes much more important. As work-interval duration increases, exercise intensity also declines, which means that creatine phosphate’s role as a buffer becomes less important.

That doesn’t mean that the value of creatine supplements becomes negligible for the endurance athlete carrying out relatively long work intervals, however, because creatine supplementation did produce significant improvements in work output during the longest (five-minute) intervals utilized in this study. Thus, it is tempting to say that creatine supplementation would be very beneficial to endurance athletes during their training (150-second to five-minute intervals are commonly employed by endurance competitors).

Will it also be true for runners?
However, remember that the gains in this study associated with creatine supplementation were obtained by endurance kayakers, not runners. Endurance kayakers, of course, are seated during exercise, and therefore the gains in weight associated with taking creatine are not so troubling to them (the kayak and water – not the athletes’ working muscles – support most of the extra weight, and the only real drawback linked with weight gain is a slight uptick in drag, i. e., friction between the kayak and the water). The same is true for cyclists, but even one-pound gains can hurt the efficiency of runners; four-pound upswings will almost certainly slow them down.

What causes the gain in weight? Research indicates that most of the short-term weight gain associated with creatine supplementation is probably due to water retention. Eric Hultman and his outstanding team of researchers were able to show recently that as creatine storage by muscles increases, urinary volume tends to decline (‘Muscle Creatine Loading in Men,’ Journal of Applied Physiology, vol. 81, pp. 232-237, 1996). Over the long term, much of the weight gain associated with creatine could be produced by an actual increase in muscular mass, as the higher-quality workouts linked to creatine supplementation could lead to advances in muscle size, at least among athletes who are strength training with rather heavy resistances.

The answer is yes – but
Should endurance runners take creatine supplements? There is little doubt that creatine supplementation can improve the quality of endurance-runners’ workouts. Several years ago, scientists from England and Estonia asked five endurance runners at Tartu University in Estonia to supplement their diets with 30 grams (six five-gram doses per day) of creatine monohydrate per day for six consecutive days. During this six-day period, five other Estonian runners of comparable ability consumed a glucose placebo instead of creatine. All runners were unaware of the true compositions of their supplements (‘Creatine Propels British Athletes to Olympic Gold Medals: Is Creatine the One True Ergogenic Aid?’ Running Research News, vol. 9(1), pp. 1-5, 1993).

run endurance - Sports Supplements - Creatine For Endurance AthletesPrior to and following the six days of supplementation, the athletes ran four 300-metre and (on a separate day) four 1000-metre intervals, with three minutes of rest between the 300-metre work intervals and four minutes of recovery after the 1000-metre reps. Creatine dramatically improved the runners’ efforts. Compared to the placebo group, improvement in the final 300-metre interval (from pre- to post-supplementation) was more than twice as great for creatine users, and improvement was more than three times as great for creatine supplementers in the final 1000-metre interval. Total time required to run all four 1000-metre intervals improved from 770 to 757 seconds after creatine supplementation, a statistically significant change. Meanwhile, placebo-group members’ performances remained the same (about 775 seconds for the four intervals). Creatine supplementation improved the average quality of the 1000-metre intervals by a little over three seconds.

Of course, improvements in workout quality generally lead to improvements in competitive performances. Amazingly enough, workout-quality upgrades can occur after just five to six days of creatine supplementation. This all makes creatine sound wonderful, but there’s still that nagging problem of weight gain.

Will you always gain weight?
However, bear in mind that the water-retention-related gain in weight is primarily a function of the high creatine-loading doses (20 to 30 grams per day) used both in many research studies and by many athletes. In a very recent study, a lower loading dose (6g of creatine per day) produced only a one-pound gain in weight (‘Why Your Creatine Consumption Is Costing You Too Much,’ Running Research News, vol. 14(7), pp. 1-4, 1998).

And in fact researchers are finding that lower loading doses can be as effective as the big, 20-gram per day intakes at building up muscle creatine-phosphate concentrations, provided that the lower doses are taken over a little bit more time. Basically, the new research is revealing that six one-half gram doses of creatine per day (for a total of three grams daily) over the course of about 30 days will build muscle-creatine concentrations to a level comparable to that achieved with the whopping 20-gram ingestions. Very importantly, these three-gram per day intakes appear to be associated with very little water retention and weight gain.

Thus, it appears that creatine monohydrate can be a performance-boosting (and legal) supplement for endurance runners. The best way to take it is to simply sprinkle about a half-gram of the stuff on some food (and then of course eat the creatine and comestible) six times per day. Little creatine will be lost in the urine and faeces, creating a very economical intake pattern, little weight will be gained, and the resulting heightened intramuscular creatine-phosphate concentration should have a direct, positive impact on the quality of your high-intensity training sessions. Since intensity is the most potent producer of running fitness, your creatine-boosted sessions should eventually lead to some very nice PBs.

Bear in mind that there’s no need for you to buy ‘special’ creatine. ‘Micronized’ creatine and any commercial creatine product which supposedly can be absorbed more readily offers no special advantages; in fact, as the rate of creatine absorption increases, the urinary losses of creatine become greater.

Jim Bledsoe

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Original Cal-Mag Formula – Natural sleeping draught and pain suppressant

cal mag - Original Cal-Mag Formula - Natural sleeping draught and pain suppressantCalcium Magnesium Ratio

The proven ratio used in the Cal-Mag Formula is one part elemental magnesium to two parts elemental calcium.

As the Cal-Mag Formula calls for precise amounts of these elemental substances, some further explanation of these quantities should be given here.

The Cal-Mag Formula is made using the compounds calcium gluconate and magnesium carbonate. Both of these come in white, powdery form. Each is a compound of different substances. In other words, calcium gluconate contains other substances beside calcium; it is not all pure calcium but contains only a percentage of pure elemental calcium. Similarly, magnesium carbonate contains other substances besides magnesium, and includes only a percentage of pure elemental magnesium.

But it is the amount of elemental magnesium in correct ratio to the amount of elemental calcium that is important in the preparation of the Cal-Mag Formula. This does not mean that you use pure magnesium or pure calcium when you make Cal-Mag. Use only calcium gluconate and magnesium carbonate.

Magnesium Carbonate. The desired compound for Cal-Mag, called magnesium carbonate basic, contains 29 % magnesium. (This compound is also sometimes called magnesium alba.)

There are different magnesium compounds with different percentages of elemental magnesium, but using any kind other than that recommended here will give varying amounts of magnesium which will violate the needed ratio of one part magnesium to two parts calcium.

It is magnesium carbonate basic, containing 29 % elemental magnesium which is used in making Cal-Mag and it is essential to ensure that the magnesium carbonate basic which is used is fresh, not old.

Calcium Gluconate: There is only one kind of calcium gluconate compound and 9 % of that compound is calcium, so there is no problem in selecting the correct calcium gluconate compound for the Cal-Mag preparation.

The Cal-Mag Formula

Note, again, that the ratio is one part elemental magnesium to two parts elemental calcium. If one wants to work this out precisely, one can work out the elemental amounts.

The Cal-Mag Formula below has been given the compound amounts:

  • Put 1 level tablespoon of calcium gluconate in a normal-sized drinking glass.
  • Add one half level teaspoon of magnesium carbonate.
  • Add 1 tablespoon of cider vinegar (at least 5 % acidity).
  • Stir it well.
  • Add one half glass of boiling water and stir until all the powder is dissolved and the liquid clear. (If this doesn’t occur it could be from poor grade or old magnesium carbonate, or insufficient cider vinegar.)
  • Fill the remainder of the glass with lukewarm water or cold water and cover.
  • The solution will stay good for two days.

Make a Palatable Cal-Mag

There is warning regarding Cal-Mag. Variations from the above can produce an unsuccessful mess that can taste pretty horrible. It can be made incorrectly so that it doesn’t dissolve and become the most unpalatable, ghastly stuff anybody
ever fed anybody. Possibly when made incorrectly it is even unworkable.

There is also the factor that one should mix the solution in exactly the correct proportions and approach the dosage on the cautious side, as an overdose of magnesium can cause diarrhea. I doubt, however, that as much as three glasses of
properly mixed Cal-Mag would bring about that condition.

Made correctly, Cal-Mag is very clear liquid, pleasant to take and palatable. Thus the directions should be followed very explicitly, to produce a proper Cal-Mag that is both pleasant to take and beneficial.

Cal-Mag has been found to have added benefit of balancing out the vitamin B1 used on the program, as vitamin B1 taken without calcium can cause serious teeth problems by setting up an imbalance of vitamins and minerals.

Handling Withdrawal

The use of Cal-Mag has been used very effectively during withdrawal to help ease and counteract the convulsions, muscular spasms and severe nervous reactions experienced by an addict when coming off drugs (including smoking).
The success of its application for withdrawal cases by drug rehabilitation centers such as Narconon has now been established. Cal-Mag has been reported as effective in withdrawal from any drug, its effectiveness most dramatically
observable with methadone and heroin cases.

Methadone attacks bone marrow and bones so one usually encounters a severe depletion of calcium in methadone users, characterized by severe pain in joints and bones, teeth problems, hair problems. Getting calcium into the system (in the acidic solution in which it can operate), along with magnesium for its effect on the nerves, helps to relieve these conditions.

It has been reported that with use of Cal-Mag, a person can be withdrawn from methadone anywhere from two weeks to three months faster than without its use. This may apply in withdrawal from other drugs as well.

Since drugs (including nicotine) or alcohol burn up the vitamin B1 in the system rapidly, taking a lot of B1 daily when coming off drugs helps to avoid the convulsions which often attend this deficiency. The B1 must, of course, be flanked with other vitamin dosages to maintain a proper balance of needed nutrients. And, accordingly, sufficient quantities of Cal-Mag are needed, both to prevent created mineral deficiencies and to work its wonders in easing and relieving the agonies accompanying withdrawal.

From 1 to 3 glasses of Cal-Mag a day, with or after meals, replaces any tranquilizer and sleeping draught. It does not produce the drugged effects of these (which are quite deadly).

An Easy Mix Method – Herbal Drink

  • Order and mix together 77.5 grams magnesium carbonate and 500 grams calcium gluconate.
  • Put 3 level medicine measures of powder mix and 3 medicine measures of cider vinegar in cup or mug and stir.
  • Fill cup slowly with boiling water while stirring.
  • If mixture is not clear, add a little more cider vinegar as it may not have had the required acidity.
  • Add Rooibos tea bag (or any herbal tea of choice) and sweeten to taste with Stevia powder or liquid.
  • Drink hot or cold 3 times daily, especially last thing at night to sleep well.
  • It is a natural sleeping draught and pain suppressant.
  • Also helps alleviate female PMS, period pains and osteoporosis.
  • Note: On first taking this, some persons may experience mild flatulence and diarrhea which usually clears after a few days as the body adjusts.

Sports nutrition – A training strategy for protein consumption

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.

Is leucine a ‘special-case’ BCAA?

Leucine is the most studied of the BCAAs, partly because leucine and its metabolites have been reported to inhibit protein degradation (22). In the body, leucine accounts for about 4.6% of all amino acids and is involved in many important roles in the body, such as regulating protein metabolism by inhibiting degradation and stimulating synthesis .

Of particular interest is the fact that leucine can be oxidised to a compound known as acetylCoA in muscles at a higher rate than the other BCAAs (valine and isoleucine). This is important because acetylCoA is an ‘entry point’ into the citric acid cycle, one of the main energy-producing pathways in the body, and itself the gateway to aerobic metabolism, which explains why the demands for leucine rise substantially during periods of high energy expenditure. Studies have also shown that leucine oxidation is increased under catabolic conditions, such as depleted muscle glycogen.

Some researchers believe that the current leucine requirement, set at 14mg per kg of body weight per day, should be increased to 30mg in people who regularly participate in endurance activities. This argument is supported by research that suggests endurance athletes can actually burn more leucine than they take in through the RDA of protein.

One of the best-known leucine metabolites is a compound called ß-hydroxy ß-methylbutyrate, Is leucine a ‘special-case’ BCAA? more commonly known as HMB, which is popular with bodybuilders and athletes as a muscle/strength building supplement. But what is the evidence that it actually works? Recent research indicates that 1.5-3g per day of HMB supplementation can increase muscle mass and strength, particularly in untrained subjects beginning training and in the elderly. The muscle mass gains in these studies are typically 0.5-1kg greater than for controls during 3-6 weeks of training.

There is also recent evidence that, in athletes, HMB may reduce the catabolic effects of prolonged exercise. In one study, 13 runners were split into two groups, one taking 3g of HMB per day and the other a placebo. Both groups continued with their normal training for six weeks, after which they completed a 20k run. Before and after the run, creatine phosphokinase and lactate dehydrogenase levels (both measures of muscle damage) were measured, with the HMB group showing much smaller increases in both than the placebo group, indicating significantly reduced muscle damage.

However, the long-term effects of HMB supplementation in athletes are less clear. Most studies conducted on trained subjects have reported non-significant gains in muscle mass(34-36), but further research is needed to clarify whether HMB really does enhance training adaptations in athletes.

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

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