Supplement Performance - Proteins Carbs Dominate the Field

A Sports Supplement Update

The importance of protein in nutrition and health cannot be overemphasized. Proteins are nutritionally essential because of their constituent amino acids, which the body must have to synthesize its own variety of proteins and nitrogen-containing molecules that make life possible.

Clearly, gym rats need more protein than couch potatoes. In general, sports nutritionists recommend that athletes eat about 1.5-2.0 grams of protein per kilogram of body mass. However, the testimonials of hardcore gym rats who believe their success depends on consumption of enormous amounts of protein (e.g., 3.5 grams per kilogram) suggest that further lab investigations are necessary before the question of protein need is settled regarding those attempting to maximize muscle mass. Obviously, it’s possible these gym rats “enrich” their protein shakes with anabolic steroids, which maximizes protein utilization (“Manninen, dude, are you a NASA rocket scientist?”).

Whatever the case, the very high protein intake appears to promote muscle growth and has few, if any, adverse effects. Carbohydrate’s primary function is supplying energy for cellular work. Aerobic breakdown of carbohydrate for energy occurs more rapidly than energy generation from fatty acids. Thus, depleting glycogen reserves significantly reduces exercise power output. Moreover, physically active individuals need to be much less concerned about excess dietary carbohydrate intake resulting in surplus body fat storage compared to their sedentary counterparts because this substrate is used to replenish carbohydrate stores depleted by exercise training/competition sessions.

It’s now crystal clear that the timing of nutrient intake is also important. Consuming nutrients after exercise facilitates nutrient transport into muscle cells by enhanced hormonal milieu, particularly higher insulin and lower catecholamine (adrenaline, noradrenaline) levels, and increased sensitivity to insulin and intracellular transporter proteins.

Amino acids with or without carbs boost protein synthesis after resistance exercise. However, consumption of both protein and carbohydrate results in even greater effects on protein balance. Further, consumption of this same protein-carb supplement immediately before resistance exercise results in increased amino acid delivery to muscle and greater net muscle protein synthesis compared with consumption of the supplement at various times after exercise.

With that said, this article summarizes the latest findings on proteins, carbs, amino acids, creatine, etc.

Nutrition for Serious Gym Rats

The state-of-the-art review by Dr. Jeff Volek at the University of Connecticut summarized the influence of nutrition on responses to resistance training³. The take-home messages were as follows:

                        • Gym rats supplemented with whey protein (1.2 grams per kilogram of body mass) had greater increases in lean body mass compared with the control group, indicating that whey protein promotes anabolism during resistance training. Further, provision of additional essential amino acids (leucine, isoleucine, valine, etc.) can prevent the acute stress response associated with short-term resistance training overreaching.

                        • Carb supplementation before, during and after resistance exercise can attenuate the rate of muscle glycogen depletion during exercise and speed the rate of glycogen re-synthesis after exercise, which may enhance performance. Further, one study showed that carb intake during resistance exercise significantly blunted the cortisol response. Importantly, this study also showed that the reduction in post-exercise cortisol was significantly related to increases in muscle growth.

                        • A protein-carb supplement consumed before and immediately after resistance exercise enhances the acute growth hormone response. Dr. Volek also noted that there appears to be an interaction between increased availability of amino acids and increased insulin sensitivity after exercise and the timing of supplement ingestion may be important to maximize the anabolic response. So, he suggested that consumption of a protein-carb supplement at times around exercise (i.e., immediately before and immediately after) may provide the ideal anabolic situation for muscle growth.

Carb-Protein Supplementation During Exercise

The purpose of the recent study by Dr. Michael Saunders and colleagues at James Madison University was to examine whether cycling performance and post-exercise muscle damage were altered when consuming a carb-protein beverage versus a traditional carb-only beverage (Gatorade^). The authors concluded that a carb-protein beverage produced significant improvements in the amount of time to fatigue and in reductions in muscle damage. As discussed by the authors, there are at least two mechanisms by which performance may be improved by the addition of protein to a carbohydrate beverage. First, the protein may facilitate faster fuel transport across the lining of the gut. Second, performance may have been aided via improved insulin stimulation during exercise. In sum, it’s becoming increasingly clear that the traditional sports drinks containing only carbs are yesterday’s news.

Of course, the Gatorade^ people tried to refute these findings. According to the Gatorade Sports Science Institute Statement on New Sports Drink Research Regarding Protein During Exercise, “We have several

concerns about this specific study. While the researchers used Gatorade-brand powder to formulate the carbohydrate-only sports drink, it was mixed to a 7.3 percent concentration. The package mixing instructions recommended, and research indicates, that Gatorade should be consumed as a six percent carbohydrate solution. Also, while the two sports drinks contained the same amount of carbohydrates, they were not calorie matched, making it impossible to tell if the effects of the carbohydrate-protein sports drink resulted from additional calories or from the protein itself.”

However, it’s clear the addition of carbs above six to 10 percent concentration in sports drinks does not produce additional benefits. Therefore, if adding protein to a drink of similar carb concentration produces performance benefits, it’s a significant finding from a practical perspective. Although the carb beverage had slightly higher carb content than Gatorade’s instructions (7.3 percent vs. six percent), composition of the carb drink was still within the range considered to be optimal for sports drinks.

According to the recent International Society of Sports Nutrition Position Stand on Sport Drinks Containing Protein, “A fair and honest debate about the merits of different sports nutrition and supplementation strategies is needed to provide consumers with the best information available… Ultimately, whether one consumes a traditional sports drink versus a protein-containing sports drink is up to each individual. Based on the findings of the James Madison University study as well as others, it seems reasonable that [carbohydrate-protein] products may provide superior effects at increasing endurance and decreasing muscle damage.”

Post-Workout Protein-Amino Acid Supplementation

The recent well-controlled study by Dr. Elisabet Borsheim and co-workers at the University of Texas Medical Branch tested the hypothesis that (a) a mixture of whey protein, amino acids and carbs stimulates muscle growth to a greater extent than carbs alone after resistance exercise, and (b) that the stimulatory effect of the mixture will last beyond the first hour after ingestion.

Not surprisingly, the results indicated that a mixture of whey protein, amino acids and carbs (Pro Performance Distance^) stimulated muscle growth to a greater extent than carbs alone. Further, the addition of protein to a mixture of free amino acids carbs resulted in a response lasting beyond the first hour after exercise. The authors estimated that about 18 grams more muscle was synthesized in response to the protein amino acids carb drink versus carbs alone. So, a muscle gain of 864 grams wet mass (water content of muscle is about 73 percent) can be predicted over 12 weeks, as compared to 216 grams with the carb drink.

Even Chocolate Milk Beats Gatorade^

Dr. Janet Walberg-Rankin and co-workers at Virginia Tech compared body composition and muscle function responses to resistance training in males who consumed a carb drink (Gatorade^) or chocolate milk following

each training session. Chocolate milk consumption immediately after each workout tended to increase lean body mass and bodyweight compared to supplementation with carbs.

This study clearly shows that carbs-only post-exercise beverages don’t cut it. However, it’s also clear that chocolate milk is not the optimal post-exercise drink.

In my opinion, recovery sports drinks containing protein hydrolysates may be of great value. Protein hydrolysates containing mostly di- and tripeptides are absorbed more rapidly than free-form amino acids and much more rapidly than intact proteins. In addition, there is evidence that protein hydrolysate ingestion has strong insulinotropic effect. However, more research is needed before firm conclusions can be drawn.

Exercise and Branched-Chain Amino Acids

Apart from acting as a protein supplement, amino acids alone or in various combinations can have specific physiological and pharmacological effects. In fact, certain amino acids exert effects similar to hormones and drugs. Thus, amino acids can transcend their roles of being just the building blocks of protein.

The branched-chain amino acids (BCAAs) leucine, isoleucine and valine are so named because they have a carbon chain, which deviates or branches from the main linear carbon backbone. They are unusual in that they are catabolized mainly in skeletal muscle.

Recently, Dr. Yoshiharu Shimomura and co-workers from Japan reviewed effects of BCAA supplementation on skeletal muscle during exercise. It has been reported that BCAA supplementation (77 milligrams per kilogram of body mass) before exercise suppressed muscle protein breakdown. However, additional studies are required to clarify the optimal amount of BCAA supplementation for beneficial effects. Although it’s now clear that leucine is the most potent amino acid among the BCAAs for stimulating protein synthesis, supplementation of leucine alone may cause BCAA imbalance.

Finally, toxicity studies using animals show that BCAAs are safe amino acids when the three BCAAs are provided in a ratio similar to that of animal protein (i.e., a 2:1:1 leucine:isoleucine:valine ratio).

Creatine Supplementation and Gym Rats

The recent review by Drs. Jeff Volek and Eric Rawson presented scientific basis and practical aspects of creatine supplementation. Creatine ingestion during heavy resistance exercise results in significantly greater increases in cross-sectional areas of muscle fiber compared with a placebo (fake supplement). Further, numerous studies have indicated that resistance exercise performance is increased after a creatine-loading regimen. For example, maximal bench press and leg press were increased eight and 16 percent, respectively, in the group using creatine and resistance training. It’s been demonstrated that insulin infusion increases muscle creatine accumulation; however, insulin abuse is very risky business.

It has also been demonstrated that carbs (about 90 grams four times per day) increase muscle creatine accumulation. However, these doses are clearly impractical. Fortunately, a more recent study showed that the ingestion of creatine with 50 grams of protein and 50 grams of carbs results in similar muscle creatine increases as ingesting creatine with about 100 grams of carbs. Not surprisingly, the authors concluded that the predominance of research indicates that creatine supplementation represents a safe, effective and legal method to enhance muscle size and strength responses to resistance exercise.

HMB Boosts Strength

The purpose of recent study Dr. J.S. Thomson at Massey University in New Zealand was to validate or dispute claims of increased strength, increased fat-free mass and decreased fat mass with HMB supplementation during a period of resistance training. A randomised double-blind, placebo controlled study was used to investigate the effects of supplementing 34 resistance trained men with three grams/day of HMB or cornstarch placebo on strength and body composition over nine weeks of supplementation. This study found no effect of HMB supplementation on body composition; however, there was a significant increase in leg extension strength with HMB supplementation in response to resistance exercise.

Bicarbonate: Still the Best Buffering Agent

Athletes have practiced bicarbonate loading for over 70 years, with sodium bicarbonate being ingested in the form of the household baking soda. The most popular protocol for bicarbonate loading is to ingest about 0.3 grams of sodium bicarbonate per kilogram of body mass one or two hours prior to exercise. There are numerous studies showing that bicarbonate (or citrate) loading may be a useful strategy to enhance the performance of athletic events that are conducted at near maximum intensity for the durations of one to seven minutes (e.g., 400-1,500-meter running). However, sports that are dependent on repeated anaerobic bursts (e.g., bodybuilding) might also benefit from bicarbonate loading.

The goal of a recent study by Dr. Marije Van Montfoort and colleagues was to compare the effect of ingestion of sodium bicarbonate with that of other potential buffering agents. The authors concluded that bicarbonate is possibly more beneficial to sprint performance than lactate and probably more beneficial than citrate or chloride.

Rhodiola Rosea Boosts Endurance

A number of beneficial effects, such as increased muscle strength and suppression of mental fatigue, have been attributed to the intake of Rhodiola rosea extracts. Thus, the purpose of the recent study by Dr. Katrien Bock and colleagues was to examine the effects of Rhodiola rosea intake on physical capacity, muscle strength, speed of limb movement, reaction time and attention.

The primary finding was that acute Rhodiola rosea intake (200 milligrams) increased endurance capacity. However, it did not impact on muscle strength. The authors suggested that Rhodiola rosea could stimulate endorphin action during exercise.

Modafinil Fights Fatigue During Exercise

Modafinil is actually not a supplement. Rather, it’s a psychostimulant that has been used for a number of years in the treatment of narcolepsy and hypersomnia. Drs. Ira Jacobs and Douglas Bell at the Defense Research and Development in Toronto examined the effect of acute ingestion of modafinil (four milligrams per kilogram of body mass) on time to exhaustion during high-intensity exercise.

The results indicated that ingestion of modafinil prolonged exercise time to exhaustion. Also, no untoward side effects were reported by the subjects. The authors concluded Modifinil can indeed enhance physical performance of a nature that would likely be advantageous during competitive sports where exercise to exhaustion is commonplace.

How to Do a Free PubMed Search

Even where a sports supplement does not produce a true physiological effect, a person might attain some performance benefit because of a psychological boost or placebo effect. The placebo effect describes a favorable outcome arising simply from an individual’s belief he/she has received a beneficial treatment. Thus, we need placebo-controlled studies examining effects of various supplements on exercise performance and body composition.

In addition to reading Muscular Development, you can do your own PubMed Search. First go to the National Institute of Medicine’s website located at www.pubmed.com. If you want to find information on creatine related to exercise, search “creatine supplementation and exercise.” Then, just click on the author’s name to see what the paper was about. The abstract contains some information about how the study was carried out and what the results were. In some cases, the reference will also contain a link that will allow the free full text (complete) paper to be downloaded.

The most reputable journals publishing sports supplement-related papers are Medicine & Science in Sports & Exercise, International Journal of Sports Nutrition and Exercise Metabolism, Journal of Applied Physiology, American Journal of Physiology and Sports Medicine. It should be noted, however, that not all scientific journals are indexed in PubMed. For example, Sports Nutrition Review Journal (http://www.sportsnutritionsociety.org/site/journal/journal_index.php) is indexed in SPORTDiscus. So, you can’t find Sports Nutrition Review Journal abstracts from PubMed.

Most sports supplement-related papers published in the general medical journals are of poor quality simply because they are often written by “average” doctors/scientists and are not subject to peer review by the sports nutrition scientists. For example, Lancet (351:1252-1253, 1998) published a