Soy protein is just as effective as whey protein in helping to maintain performance when athletes have to complete successive training sessions. In a study assessing fitness training in football players, participants had to complete two gruelling speed-endurance sessions with just one day’s rest between. As expected, performance was impaired on the second session, but taking either soy or whey protein supplements helped reduce those impairments to the same extent, with both resulting in improved high-intensity running performance compared to a placebo group.