Exercise adds a new dimension to the issue because the body, with an increased need for protein, has to rely heavily upon dietary sources rather than draw from it's own stores. If this need is not met during exercise then the body will start to draw upon its muscle tissue as a source. Though it may seem that humans don't need much protein, the facts haven't been established as to how much an exercising individual should be taking in. Recent research shows that the RDA doesn't appear to meet the needs of exercising adults. One of the top researchers in this field, Dr Peter Lemon, stated in a recent review paper that, "the RDA for those engaged in strength training should be about 1.7 – 1.8 grams of protein per kilogram of body mass per day". Dr Lemon came to this conclusion after citing several studies (Fern, 1991, Tarnopolsky et al., 1992) which used amounts of protein ranging from 1.3 – 3.3 grams of protein per kilogram of bodyweight. At Kent University researchers tested 3 different groups of people: 1) on a low protein diet which was 0.9 grams of protein per kilogram of bodyweight; 2) another group eating 1.4 grams of protein per kilogram of bodyweight; and 3) a group eating 2.4 grams of protein per kilogram of bodyweight. Both sedentary and strength training groups were involved. The results showed that 1.4 grams resulted in protein synthesis while there were no changes in the low protein group and, finally, the group that ingested 2.4 grams of protein did not see any more increased protein synthesis than the 1.4 grams of protein group.
Another study conducted at the Letterman Army Institute of Research in San Francisco showed that subjects on a higher protein intake (2.8 g/kg/day), coupled with intense strength training, gained a whopping 3.28 kg (7.2 lbs) of lean mass. The study was done over a 40-day period and the subjects were trained to near exhaustion (2). Another study of weightlifters over a 3 month period, with the protein increased from 2.2g/kg/day to 3.5 g/kg/ day, resulted in a 6% increase in muscle mass and a 5% increase in strength (3). Susan M Klieiner, who holds a PhD in nutrition and human performance from Case Western Reserve University,<and has conducted research on steroid assisted athletes> states in her book, Power Eating, that for muscle building an intake of 1.6-2.2 grams per kilogram of bodyweight is recommended. Dr Michael Colgan, in Optimum Sports Nutrition, claims that the RDA doesn't meet the needs of athletes who train in an intense fashion. So, the evidence provided by some of the highly regarded "experts" in this field indicates that the addition of extra protein has been shown to display positive effects which produce muscle growth
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