Supplement Performance - ATP, NAC, Protein Hydrolysates
A Sports Supplement Update
ATP and Exercise Performance
The energy in food does not transfer directly to the cells for biological work. Rather, energy from macronutrient burning becomes harvested and funneled through the energy-rich compound adenosine triphosphate (ATP). The ATP molecule powers all of the cell’s energy-requiring processes. Although it has been presumed that enzymes in the digestive track would catabolize the orally administered ATP before it could get into the muscle,1 some animal studies have shown that chronic oral administration of ATP produces notable alterations in physiology.2
Recently, Dr. Alexander Jordan and colleagues at The Cooper Institute examined 14 days of oral ATP supplementation on indices of anaerobic capacity and muscular strength.3 In a double-blind manner, subjects (27 healthy men) received an oral dose of low-dose (150 milligrams) or high-dose (225 milligrams) enterically coated ATP, or matched placebo (fake supplement). Enterically coating may enhance the absorption of the whole molecule or protect the molecule through the digestive tract, attenuating degradation or protecting the molecule from the lower pH level of the gut.
Investigators observed no significant difference between group treatment effects for any of the Wingate anaerobic power test or bench press parameters. However, investigators did observe small treatment effects for subjects ingesting high-dose ATP. These effects included an 8.13-kilogram (39.9 pounds) increase in the average one-revolution maximum (1-RM) during the acute treatment condition, a 2.55-repetition increase in set one reps at day 14 and a 704-kilogram (1,548.8-pound) improvement in day 14 total lifting volume versus non-supplemented baseline condition. However, an examination of the blood ATP concentrations failed to yield meaningful data. Thus, although these results are intriguing, more research is needed before any conclusions can be drawn.
NAC Fights Muscle Fatigue
N-acetyl-L-cysteine (NAC) is the N-acetyl derivative of L-cysteine (a nonessential amino acid). NAC has been shown to have hepatoprotective effects against various toxic liver compounds such as alcohol. Much of the protective effects are due to NAC´s antioxidant properties and its ability to increase cellular levels of glutathione (GSH). GSH plays a major role in protecting skeletal muscle and other body tissues from oxidative damage.
Dr. Ivan Medved and colleagues at Victoria University of Technology in Australia investigated the effects of NAC on time to fatigue during prolonged, submaximal exercise in endurance athletes. Eight males completed a double-blind, crossover study, receiving NAC or placebo before and during cycling. NAC was intravenously infused prior to and throughout exercise. The authors concluded that NAC improved performance in well-trained individuals, with enhanced muscle cysteine and GSH availability a likely mechanism. However, effects of oral NAC on exercise performance remains to be determined.
Protein Hydrolysates and Sports Drinks
Protein can be hydrolyzed, producing small chains of amino acids called peptides. Several studies have shown that protein hydrolysates containing mostly di- and tri-peptides are absorbed more rapidly than free-form amino acids and much more rapidly than intact proteins. In addition, there is recent evidence that protein hydrolysate ingestion has strong insulinotropic effect. Thus, recovery sports drinks containing protein hydrolysates may be of great value. I recently published a paper in the Journal of Sports Science and Medicine examining some science behind protein hydrolysates as it is applied to sports and exercise.5 The free full-text paper is available at www.jssm.org.
Supplements for Bodyweight Reduction
The objective of the recent systematic review by Drs. Max Pittler and Edzard Enrst was to assess the evidence from rigorous clinical trials, systematic reviews and meta-analyses on the effectiveness of dietary supplements in reducing bodyweight.6 The results can be summarized as follows:
- There is considerable doubt that chitosan is effective.
- The observed effect with chromium picolinate is, although statistically significant, not clinically meaningful.
- A systematic review of five double-blind trials, including two trials about which it is unclear if their formats were randomized or non-randomized, concluded that the combination of ephedrine/ephedra and caffeine is effective for reducing bodyweight and appears to outweigh the risks.
- The evidence for Garcinia cambogia is not compelling.
- Guar gum is not effective in reducing bodyweight.
- Concerning HMB, there are encouraging data that require further independent replication.
- The case for pyruvate as an aid to body composition changes and weight loss is weak.
- Yerba maté might potentially be effective in lowering bodyweight.
- It is unclear whether yohimbine is effective in reducing bodyweight.
Influence of Nutrition on Responses to Resistance Training
The recent paper by Dr. Jeff Volek at the University of Connecticut summarized the influence of nutrition on responses to resistance training.7 According to Dr. Volek, consumption of a protein-carbohydrate supplement at times around exercise (i.e., immediately before and immediately after exercise) may provide the ideal anabolic situation for muscle growth. Further, men who supplemented with whey protein (1.2 grams per kilogram of body mass) had greater increases in lean body mass compared with a placebo group after six weeks of resistance training. Total protein was nearly twofold higher in the whey protein vs. the placebo group, indicating additional whey protein promotes anabolism during resistance training. Finally, the provision of additional essential amino acids can prevent the acute stress response associated with short-term resistance training overreaching.
