Be careful of your Soy intake if you want strength gains.
As we age we suffer the loss of muscle tissue, time and time again whey protein supplementation has been proven to promote muscle protein synthesis. However in a recent study on aging men supplementing with 27grams of Soy protein post recovery (straight after exercise) caused lower strength gains in comparison to those receiving a dairy based protein supplement.
In soya there are Estrogen like compounds called phytoestrogens which bind to receptors, decrease sperm count and have a feminizing effect. Because soy acts like a weak estrogen it effects testosterone which could explain why strength gains are reduced.
In another study it was found that supplementing with 55grams of Soy for a month decreased blood testosterone levels by 19 percent at the same time increasing estrogen receptor activity. Testosterone levels did return to normal after discontinuing Soy use.
Thomson R, L et al Muscle strength gains during resistance exercise training are attenuated with soy compared with dairy or usual protein intake in older adults: A randomized controlled trial. Clinical Nutrition, 35 27-33, 2016