Specifically, let's take a look at a three-month study looking at the effects of different protein types on body composition during a strength training program.
In this study, the researchers provided daily supplements containing 50 grams of a variety of proteins — either soy concentrate, soy isolate, a soy isolate/whey blend, or a whey blend.
Twenty participants added these supplements, in conjunction with a resistance training program. At the end of the three months, a significant increase in muscle mass was noticed with all of the protein supplemented groups. Interestingly, no significant differences were found among Testosterone, body fat, or body weight between the groups.
In the end, the authors concluded that 12 weeks of soy protein supplementation (50 grams per day) was as effective as the other protein types when it comes to boosting muscle mass during a strength training program.
Interestingly, as some people have suggested, soy supplementation doesn't seem to decrease Testosterone or limit lean body mass gains. It's important to note that similar studies have been done using soy-containing supplemental nutrition bars, and the results have been consistent.
In another study using rats and endurance exercise, the authors concluded that protein synthesis was comparable between rats fed different protein-containing meals after exercise — including soy.
In yet another study, researchers found that elite gymnasts supplementing with soy protein (1 g/kg) for four months, saw favorable changes in their stress responses to training (when compared to the gymnasts not using any supplemental protein at all).
Finally, a Romanian study using Olympic athletes supplemented participants with soy protein (1.5 g/kg) for eight weeks. In the end, the authors found that the soy protein supplementation led to increased body mass (approximately 3 kg, mostly from lean body mass) and strength indexes. Significant decreases of fatigue were found after training sessions. No negative side effects or abnormal changes to metabolism were noticed and the product was well tolerated.
). Proteiinidrinkkejä mukaan jne.