The Effects of Amino Acid Supplementation
On Muscular Performance During Resistance Training Overreaching
Protein and amino acids are an important part of an athlete´s diet and as such, have been the subject of a great deal of discussion and controversy. Although it’s clear that athletes engaged in heavy training need more protein than sedentary people,1,2,3 the usual consensus is that there are no valid scientific studies to show that protein and amino acid supplements have an advantage over high-quality protein foods. The advantages usually cited for the use of supplements include convenience of preparation and storage, and ability to raise protein intake for those who wish to minimize caloric intake.
Since the 1989 ban on tryptophan for supplements in the U.S., the number of amino acid mixtures as dietary supplements has dropped. The comparative higher cost and poorer organoleptic properties of free-form amino acid mixtures relative to high-quality grades of protein and protein hydrolysates have also contributed to their decline in popularity. Moreover, there is no evidence that shows any advantage to using the much more expensive freeform amino acids simply to augment protein intake. However, there are times
when the use of amino acid mixtures may be more useful than either highprotein foods or intact protein supplements.
New Amino Acid Study
The purpose of a recent study by Dr. Nicholas Ratamess and co-workers was to examine effects of amino acid supplementation on muscular strength, power and high-intensity endurance during short-term resistance training overreaching.4 (Overreaching is a short-term training phase in which the volume
and/or the intensity of resistance exercise is increased beyond normal). It was the authors´ hypothesis that amino acid supplementation, by enhancing recovery between workouts, would maintain muscle strength and power during the initial unaccustomed stress of resistance training overreaching.
In order to examine this hypothesis, a double-blind randomised study was employed using two experimental groups (amino acid or placebo) thatunderwent four weeks of resistance training overreaching followed by a two week reduced volume/frequency phase. The training program consisted of two weeks of moderate-intensity, high-volume resistance training and two weeks of high-intensity and a lower volume of resistance training. Acute overreaching was produced by training the whole body on consecutive days, thereby
minimizing recovery between workouts. Muscular strength, power, and highintensity endurance were assessed every two weeks.
Subjects assigned to the amino acid group ingested a total of 0.4 grams per kilogram body weight of an amino acid supplement per day divided intothree daily doses. In addition, each participant was instructed to ingest the supplement separate from meals— one hour before a meal and two hours following a meal. The composition of the amino acid supplement is presented in Table 1. Subjects in the placebo group received the same instructions and ingested the same number of capsules as the amino acid group. According to
the authors, none of the subjects were taking any medications, nutritional supplements or anabolic drugs that would confound the results of this study.
Results indicated that one repetition maximum squat and bench press decreased significantly after week one of the protocol in the placebo group, whereas no change was observed in amino acid group. After week two of protocol, 1-RM squat and bench press reached baseline values in the placebo group, whereas a significant increase in 1-RM squat was observed in the amino acid group. Peak power during the ballistic bench press decreased significantly in the placebo group after week two of the protocol, whereas no difference was observed in the amino acid group. After week four, peak power during the ballistic bench press returned to baseline values in the placebo group, but a trend for improvement was observed in the amino acid group. No differences were observed in circumferences, bone mineral density, or body composition. According to the authors, the duration of the experimental protocol may not have been long enough to significantly increase muscle mass in resistancetrained men.
Table 1. Composition of the Amino Acid Supplement
Used in Ratamess Study
Amino Acid mg/tablet g/100g
Leucine 250 27.2
Lysine 130 14.1
Isoleucine 125 13.6
Valine 125 13.6
Threonine 70 7.6
Cysteine 30 3.3
Histidine 30 3.3
Phenylalanine 20 2.2
Methionine 10 1.1
Tyrosine 6 0.7
Tryptophan 4 0.4
How Did Amino Acids Improve Performance?
The mechanism(s) by which amino acid supplementation improved muscular performance is unclear. However, the amino acid supplement contained high amounts of branched-chain amino acids (leucine, isoleucine, valine, BCAA) and BCAA have been investigated for their ergogenic, anticatabolic
and anabolic effects. They are unusual in that they are catabolizedmainly in skeletal muscle.
Dr. A. Alvestrad and coworkers found leucine to decrease the net degradation of muscle protein even in normal resting subjects,5 something Drs. E. Blomstrand and E.A. Newsholme suggested might aid repair and recovery and be of importance for athletes doing regular physical training.6 Further, Drs.
Coombes and McNaugthon investigated the effects of BCAA supplementation on indicators of muscle damage after prolonged exercise.7 They concluded that BCAA supplementat ion significantly reduced serum creatine kinase and lactatedehydrogenase levels following prolonged exercise, suggesting that BCAA
supplementation may reduce exercise-induced muscle damage. Researchers examined the effects of a combination of whey protein, BCAA and glutamine on various physical parameters over a 10-week period in
resistance-trained men.8 One group received 40 grams of whey protein alonewhile the second group received 40 grams of whey protein plus five grams of glutamine and three grams of BCAA. Every subject participated in a supervised weight training program geared toward promoting muscle growth. The whey
BCAA glutamine group experienced greater increases in muscular performance than the whey-only group.
Finally, Dr. E. Blomstrand and co-workers have focused on the administration of BCAA as a means of delaying central fatigue during prolonged activities, such as marathon racing, cross-county ski racing and soccermatches. When 7.5 to 21 grams of BCAA were administered before and during exercise, small improvements were reported in both physical9 and mental performance10 in some subjects. It should be noted, however, that although field studies such as these are designed to mimic the real-world situations of
athletes, such studies are often limited in scientific value. In well-controlledlaboratory experiments, the administration of BCAA was shown to have no benefits on performance during prolonged bouts of exercise.
Bottom Line
In summary, amino acid supplementation was effective for attenuating the reductions in muscle strength and power observed during the high initial stress of resistance training overreaching.
Quacky Nutrition Textbook
I just received two nutrition textbooks from Wadsworth/Thomson Learning for review: Advanced Nutrition and Human Metabolism by Groff & Gropper and Understanding Nutrition by Whitney & Rolfes. As I read Whiney & Rolfes, I was struck by the following statements:
“Protein supplements are expensive, less completely digested than protein-rich foods and, when used as replacements for such foods, often downright dangerous.”
This is not the case. Protein powders have high biological quality and are certainly not “downright dangerous.” See the review by Dr. Luke Bucci in Energy-Yielding Macronutrients and Energy Metabolism in Sports Nutrition (CRC Press, 2000) and my recent text Protein Metabolism in Exercising Humans with Special Reference to Protein Supplementation (University of Kuopio, 2002). The effect of dietary protein intake on renal function has been debated for 50 years. In cases with compromised renal function, reduced levels of dietary protein can retard the progression to renal failure. Restriction of dietary protein appears to reduce the “renal workload” and minimize glomerular filtration. By extrapolation, it is often suggested that adults avoid high-protein intakes to minimize the glomerular filtration rates. However, there is no known association of protein intake with progressive renal insufficiency during aging (Eur J Clin
Nutr, 50:734-740, 1996).
“Whey protein appears to be particularly popular among athletes hoping to achieve greater muscle mass. A waste product of cheesemanufacturing, whey protein is a common ingredient in many low-cost protein powders. Athletes and active people who want bigger muscles should know that whey protein does not increase muscle mass.”
There is some evidence suggesting that whey protein may enhance lean body mass in conjunction with appropriate training (J Nutr Biochem, 14:251-258, 2003). Whey proteins have a high biological value and
contain a relatively high proportion of branched-chain amino acids. The abundance of leucine in whey is of particular interest in this regard. Leucine plays a distinct role in protein metabolism and has been identified
as s key signal in the translational initiation pathway of muscle protein synthesis.
Another point, beyond the composition of amino acids present in whey, is the manner which whey and other intact proteins are absorbed and utilized relative to each other, as well as to free amino acid solutions.
Whey proteins have been compared to casein and a distinct difference is that whey is rapidly absorbed compared to casein. Dr. Bohe and coworkers reported that continuous stimulation of protein synthesis (via a
constant infusion of amino acids) resulted in saturation of the response within two hours (J Physiol, 532:575-579, 2001). Thus, an effective protein source would be one that could stimulate a response in the periods
between feeding, which would be additive to the net accumulation of muscle protein in the course of a day.
Further, certain amino acids and whey-derived bioactive compoundsoffer the potential to extend health benefits to active people beyond bodycomposition (J Nutr Biochem, 14:251-258, 2003). Many of the functions associated with these amino acids and whey components involve the immune system and may therefore be of particular importance to athletes in intensive training. The claim that certain whey peptides suppress appetite is being used to market some products, but well- designed studies to validate this effect are lacking (J Nutr Biochem, 14:251-258, 2003).
“People have reported that their blood cholesterol dropped while theywere on a high-protein diet, but because no studies have been conducted, such comments cannot be accepted as evidence.”
Three independent groups reported beneficial effects on body composition and blood lipids derived from direct substitution of protein for carbohydrates in the adult diet (Metabolism 40:338-343, 1991; Int J Obes,
23:528-536, 1999, Diabetes Care 25:425-430, 2002). Further, Dr. Donald Layman and colleagues recently reported that increasing the proportion of protein to carbohydrate in the diet of adult women has positive effects on body composition, blood lipids, glucose homeostasis and satiety during weight loss (J Nutr, 133:411-417, 2003). Finally, a recent study report from the Nurses´ Health Study by Dr. Hu and coworkers providesepidemiological evidence that replacing carbohydrates in the diet with protein enhanced overall quality of the diet and lowered the risk of ischemic heart disease in adult women (Am J Clin Nutr, 70:221-227, 1999).
“Large doses of branched chain amino acids [BCAA] can raise plasma ammonia concentrations, which can be toxic to the brain.” Not all studies have reported significant increases in plasma ammonia following BCAA supplementation. In fact, some studies report noeffect or that plasma ammonia or other markers of protein degradation are decreased with BCAA supplementation. In addition, of the studies reporting elevations in plasma ammonia concentrations, the ammonia levels were well within normal values reported for athletes following intense exercise or training. See the review by Dr. Richard Kreider in Overtraining in Sport (Human Kinetics, 1997).
“Postgame Meals: As mentioned earlier, eating high-carbohydratefood after physical activity enhances glycogen storage. Since people are usually not hungry immediately following physical activity, carbohydratecontaining beverages such as sports drinks or fruit juice may be preferred.”
Although more research is needed, it’s my view that sports drinks containing only carbohydrates are news of yesteryear. Although they may cut it for endurance athletes, they are sadly lacking for hard-core strengthpower athletes. I suggest you consume high-glycemic index carbohydrates (i.e. maltodextrine and/or glucose) with a fair amount (i.e., 25-35 grams) of protein immediately after training to boost glycogen and protein synthesis.
“The results of some studies suggest that creatine supplementation does enhance performance of high-intensity strength activity such as weight lifting… Still lacking are studies of athletes using commercially
available creatine products.”
There are numerous studies using commercially available creatinemonohydrate. See Creatine: The Power Supplement by Dr. Melvin Williams and coworkers (Human Kinetics, 1999).
“Research findings support the use of caffeine to enhance endurance. Caffeine may enhance endurance by stimulating fatty acid release thereby slowing glycogen use, and by attenuating the perception
of fatigue. Light activity before a workout also stimulates fat release, but in addition, the activity warms the muscles and connective tissue making them more flexible and resistant to injury. Caffeine does not offer these added benefits.”
Moderate caffeine doses appear to also increase short-term intense cycling and rowing performance and to decrease 1,500-meter swim time.
Further, recent studies have demonstrated that the caffeine-induced metabolic effects at the onset of exercise are variable and that caffeine has no effect on muscle fuel utilization after 10 minutes of exercise. These findings imply that caffeine must affect additional processes associated with skeletal muscle and/or the central nervous system in order to have a performance-enhancing effect during many types of exercise. See the review by Dr. Lawrence Spriet in Performance-Enhancing Substances in
Sports and Exercise (Human Kinetics, 2002).
”Table H14-2. Anabolic Steroids Side Effects and Adverse Reactions:
[huge list of side effects and adverse reaction including extreme aggression with hostility, mouth and tongue soreness, breathing difficulty, heart attack, stroke, liver tumors, kidney stones and disease, gallstones,
blood clots, permanent shrinkage of testes, excessive and painful erections, cramps, fatigue, etc.]”
Most anti-doping policies are at least partially based on the belief that these substances are dangerous to the health of the athlete. Although this is true in some cases, it is tough to argue this point to athletes who already make sacrifices and take many health risks as they strive for distinction and pursue dreams in their sport. Dr. Linn Goldberg and coworkers performed a randomized, controlled study to assess an approach that stressed only the negative side effects of anabolic steroids (a method referred to as “scare tactics”). After the intervention, no change in knowledge, attitudes, or intentions were observed. In fact, there was a
trend toward increased desire to use anabolic steroids among those who received the “risk-only” approach (Pediatrics, 87:283-286, 1991).
General Motors and Coca-Cola will combine to spend nearly $2 billion to sponsor Olympic sports between 1998 and 2008. The fact that drinking Coca-Cola was not consistent with the nutritional profile of elite
athletes or the worldwide health goals of the Olympic Movement no longermattered to sports officials; their minds had been colonized by Coca-Cola.
Some people ask why drugs should be banned in sports when theyare widely accepted in society and used to improve performance or treatconditions that interfere with performance at home or on the job. Finally,
many athletes have become skeptical about doping testing policies and programs. They realize that political and economic interests can cloud thevalidity and reliability of testing programs (Cutler J., Sport in Society:
Issues and Controversies, McGraw-Hill, 2001).
According to the author introduction, Whitney´s most intense interests currently include energy conservation, solar energy uses, alternatively fueled vehicles and ecosystem restoration. So, how about if next time she writes a book about solar energy or ecosystem restoration?
P.S. If you want to purchase a scientifically based sports nutritiontext, I suggest you visit at www.humankinetics.com or www.crcpress.com. Also, read every issue of Muscular Development. Our first and foremost pledge is our undying commitment to respect your intelligence and never bullshit the reader.
References
1. Manninen AH (2002) Protein metabolism in exercising humans with special reference to
protein supplementation. Masters thesis. University of Kuopio Medical School.
2. Lemon PWR (1998) Effects of exercise on dietary protein requirements. Int J Sports
Nutr 8:426-447.
3. Williams, MH (2001) Nutrition for Health, Fitness and Sport. New York: WCB/McGraw-
Hill.
4. Ratamess NA, Kraemer WJ, Volek JS et al. (2003) The effects of amino acid
supplementation on muscular performance during resistance training overreaching. J
Strength Cond Res 17:250-258.
5. Alvestrand A, Hagenfeldt L, Merli M et al. (1990) Influence of leucine infusion on
intracellular amino acids in humans. Eur J Clin Invest 20:293-298.
6. Blomstrand E, Newsholme E (1992) Effect of branched-chain amino acid
supplementation on the exercise-induced changes in aromatic amino acid
concentrations in human muscle. Acta Physiol Scand 146:293-298.
7. Coombes J, McNaughton (1985) The effects of branched chain amino acid
supplementation on indicators of muscle damage after prolonged strenuous exercise.
Med Sci Sports Exerc 27:S149.
8. Colker CM, Swain MA, Fabrucini B et al. (2000) Effects of supplemental protein on body
composition and muscular strength in healthy athletic male adults. Curr Therapeutic
Res 61:19-28.
9. Blomstrand E, Hassmen P, Ekblom B, Newsholme EA (1991) Administration of
branched chain amino acids during sustained exercise – effects on performance and on
plasma concenration of some amino acids. Eur J Appl Physiol 63:83-88.
10. Blomstrand E, Hassmen P, Newsholme EA (1991) Effect of branch-chain amino acid
supplementation on mental performance. Acta Physiologica Scand 143:2
