The answers to your questions about protein, the key element in an athlete’s nutrition program.
Protein, from the Greek word meaning «vitally important,» is a key component of an athlete’s nutrition program. Just as glucose serves as the cornerstone of glycogen, amino acids serve as the building blocks of protein. One of the most important components of cells, protein is involved in the formation of contractile tissue or muscle, it makes up a large part of the structural component of cells, it is part of enzymes, antibodies, in the blood. . . you name it, protein is part of it.
Although the primary function of protein is to provide the amino acids needed to maintain an anabolic state, it can also be used as a fuel source. This generally occurs to a greater degree when you are in a carbohydrate-depleted state (e.g., on a low-carbohydrate diet, exercising continuously for more than two hours). However, what most athletes want is to maintain the highest absolute levels of anabolism or muscle building possible. The way scientists measure this is through something called nitrogen balance.
Remember that one of the components of protein is the nitrogen molecule. In fact, nitrogen makes up about 16% of protein. So when you eat protein, you are also taking in nitrogen. If you want to put on muscle, you must avoid a negative nitrogen balance, where you take in less protein that degrades you. A positive nitrogen balance exists when your protein intake exceeds your protein breakdown.
How Much Protein Should Athletes Consume?
Talk about a controversial topic! I have met many doctors and dietitians who claim that «too much» protein is harmful. However, Peter WR Lemon, PhD, a leading expert in the field of protein and exercise research from the Applied Physiology Research Laboratory at Kent State University in Ohio, believes that the dangers of eating a high-protein diet are overrated.
I agree. No scientific evidence indicates that consuming two or even three times the Recommended Daily Intake (RDA) of protein is harmful to a normal, healthy, exercising person.
Certainly, if you have damaged kidneys, then the work you have to do to eliminate excess nitrogen would make it advisable to avoid excess protein. But I have found no evidence that eating 1 or more grams of protein per kilogram of body weight each day has a detrimental effect. In fact, in cultures where high protein intake is common, there is no evidence that the population suffers from kidney problems. The same could be said for athletes, although I would caution that if you consume a large amount of protein, you should also drink plenty of water to avoid possible dehydration.
Suffice it to say that the recommended daily allowance of 0.8 grams of protein per 2.2 pounds (1 kg) of body weight per day is grossly insufficient for athletes and sportsmen in general. Although muscle protein degradation or breakdown increases during exercise, muscle protein synthesis increases significantly for at least 24 hours after endurance or resistance exercise. If you don’t get enough protein during this time, it would make sense that you probably won’t grow or get stronger. Current research suggests that 1.5 to 2.0 grams of protein per 2.2 pounds of body weight per day is needed for people interested in packing on some mass.
What kind of protein should you eat?
Basically, the protein you eat should have the full complement of essential amino acids (which are called essential because you have to eat them, your body doesn’t make them). They include branched chains (valine, leucine, isoleucine), lysine, methionine, phenylalanine, threonine and tryptophan. Histidine is also essential for children, and arginine for infants, who cannot do as well as adults. The body produces cysteine from methionine and tyrosine from phenylalanine, so you could say that cysteine and tyrosine are conditionally essential. Incomplete proteins, such as peanut protein, do not contain the necessary balance of all essential amino acids.
Scientists compare the quality of protein sources through the biological value (BV), which measures the amount of protein retained per gram of protein absorbed. If a given protein provides all the essential amino acids in the correct proportions and is easily absorbed, its BV score will approach 100. On the other hand, if the protein is deficient in an essential amino acid, its BV score will be much lower.
Before the widespread use of whey protein, the protein sources with the highest BV (and which were used to establish the BV scale) were whole egg and human milk (BV = 100). Whey protein has a BV of around 159, even higher than whole eggs. Not only does whey protein help put on muscle, but it has potent effects on the immune system. In fact, a study by R. Kennedy, et al, found that whey protein helped stabilize or reverse tumor growth in patients with metastatic carcinoma.
When should you eat protein?
The underlying mechanisms governing muscle growth are not known at this time, but we do know this: In order to experience a net growth in muscle mass, muscle anabolism must overcome muscle catabolism. That is, you need to feed your muscles with amino acids, glucose and fat to get them as big as your rottweiler. Is that why athletes eat constantly? To bathe their muscle cells in an anabolic cocktail of amino acids and other muscle building blocks?
Based on several animal studies, scientists have suggested that muscle protein synthesis increases within 1-2 hours after exercise. In rats, just one eccentric exercise session has been shown to elevate total mixed synthetic and myofibrillar protein rates by up to 65% for up to 41 hours.
In a recent study conducted at McMaster University in Hamilton, Ontario, Canada, JD MacDougall and colleagues used six trained men to examine how protein synthesis impacts weight training. The test subjects performed a «typical» bodybuilding workout and, using technology not available at their local gym, biceps brachii muscle protein synthesis was determined four, 24 and 36 hours after exercise. The researchers found that muscle protein synthesis increased at four and 24 hours post-exercise, but returned to pre-exercise levels after 36 hours post-exercise.
The finding that muscle protein synthesis is elevated for one day after exercise is important. I have heard many times that muscles grow when you are not exercising, especially when you sleep.
But how much protein should you eat at one time, and how often should you eat? There are several schools of thought on how much protein to eat in one sitting. Based anecdotally on what I have seen work well in many people, it seems that 30 to 40 grams of protein at a time is sufficient. I have heard accounts of athletes consuming up to three times that amount, but I have not seen data indicating whether that amount is necessary or beneficial. As for how often to eat protein, I would have to say every three hours. Your digestive system is capable of processing protein relatively frequently, and keeping a steady supply on hand (or in your stomach, as the case may be) ensures that your muscles will have access to the raw materials needed to synthesize new tissue.