Consuming a whey protein beverage (Prolibra) 20 minutes before breakfast and dinner caused greater fat lose than a placebo (fake prolibra; 8 pounds versus 3.5 pounds) and helped maintain muscle mass. Substituting proteins for carbohydrates is a good strategy for weight lose. The amino acids from whey protein circulate in the blood and the liver converts them to blood sugar. They work like tiny blood sugar timed-released capsules to maintain blood sugar levels, which decreases appetite. Health experts are scrambling to find techniques to help people eat less and lose weight. Drinking a whey protein shake before meals might help. (Nutrition & Metabolism, published online March 27, 2008)

Glutamine prevents ammonia buildup during intense exercise

Ammonia is a toxin produced during fat metabolism that causes central nervous system and muscle fatigue during exercise and tissue damage. Carbohydrates are the main fuels during exercise at intensities above 65 percent of maximum effort. The muscles get carbs from glycogen stored in the muscles and from glucose (sugar) circulating in the blood. Blood sugar comes from the absorption of carbs from the gut and from carbohydrates stored or generated in the liver. Carb stores are limited, so the body uses fats and amino acids for fuel during sports such as soccer. Ammonia production increases during exercise because of the incomplete breakdown of fats. Brazilian scientists found that glutamine supplements reduced ammonia levels in professional soccer player’s performing either prolonged or short-term intense exercise. Glutamine served as an energy source during exercise, which prevented ammonia buildup. (British Journal Sports Medicine, 42: 260-266, 2008)

Caffeine increases testosterone

Many bodybuilders take caffeine pills or energy beverages containing caffeine (e.g., coffee or red bull) to increase training intensity. Caffeine is a central nervous stimulant used to prevent fatigue and promote mental alertness. Most studies show that caffeine does not increase muscle strength or power, but reduces the perception of fatigue. New Zealand researchers found that caffeine increased testosterone levels during training, with higher doses of caffeine producing higher blood levels of testosterone. Increased testosterone levels make it easier to gain muscle mass and strength with training. The study also showed that caffeine increased cortisol – a catabolic hormone linked to protein breakdown, which might nullify caffeine’s beneficial effects on testosterone. Caffeine provides an energy boost to train harder and might also promote training gains by increasing testosterone levels. (International Journal Sport Nutrition Exercise Metabolism, 18: 131-141, 2008)

N-acetylcysteine might prevent fatigue

Intense exercise can make your muscles feel like lead. You can’t maintain speed no matter how hard you try. It’s as if someone injected your legs with Novacaine. Scientists have speculated about the causes of fatigue for centuries, but still don’t have the answer. The usual suspects include fuel depletion, high acid levels and accumulation of potassium ions, calcium or inorganic phosphate. Leonardo Ferreira and Michael Reid from the University of Kentucky suggested that chemicals called free radicals that are produced naturally during metabolism might contribute to fatigue by interfering with normal communications in the cells and damaging critical cell structures. A supplement called N- acetylcysteine (NAC) might prevent fatigue by reducing the destructive effects of free radicals. NAC is used medically to break up mucous secretions and to treat acetaminophen overdose. They cited studies in animals and humans showing that NAC increased performance in leg and respiratory (lung) muscles during exercise to failure. NAC might be an effective supplement for preventing fatigue during high-intensity aerobic exercise. (Journal Applied Physiology, 140: 853-860, 2008)

Carbs plus caffeine speed recovery

Next time you have a monster work-out, consume carbohydrates laced with plenty of caffeine during the first 3 hours of recovery. Australian researchers found that supplementing carbs plus caffeine after exercise increased muscle glycogen levels 66 percent more than carbohydrates alone. Glycogen is stored carbohydrates found mainly in the liver and skeletal muscles that provides rapid energy during high intensity exercise. Optimal recovery from exercise depends on replenishing vital glycogen stores. Glycogen depletion results in poor performance and possibly injury during the next workout or competition. In the study, the researchers caused glycogen depletion in endurance athletes through a combination of carbohydrate restriction and intense, prolonged exercise. During recovery from exercise, they fed the athletes either carbohydrates (290 grams of carbs in the form of sports bars, gels and high carb sports drinks) or carbohydrates plus high doses of caffeine (580 milligrams of caffeine; 1 cup of coffee contains about 100 milligrams of caffeine). The caffeine caused higher blood levels of glucose (sugar) and insulin and increased the activity of signaling proteins that speed the rate that muscles take up glucose from the blood and build glycogen. Glycogen depletion is a well-known cause of fatigue in endurance athletes. It is also an important cause of injury and decreased performance in bodybuilders and power athletes. Taking carbohydrates caffeine supplements during recovery might be a good strategy following an intense workout or competition. However, some people cannot tolerate high doses of caffeine. Several of the athletes in the study reported difficulty sleeping during the night following the treatment. (Journal of Applied Physiology, 105:7-13, 2008)