This research article details a double-blind, placebo-controlled trial investigating the effects of protein supplementation on physical fitness improvements after eight weeks of low-volume concurrent training. Forty-four untrained adults participated, with one group receiving a whey protein supplement and the other a placebo after each training session. Both groups showed improvements in cardiovascular fitness and muscle strength, but the protein group demonstrated significantly greater gains in leg muscle strength. The study concludes that post-exercise protein supplementation enhances adaptations, particularly in lower body strength, for untrained individuals undertaking low-volume concurrent training. This finding is significant for optimising time-efficient training and improving health outcomes.