Resistance training enhances the physiological benefits of dietary protein intake for muscle maintenance and functional health.

Study: Effect of a protein intervention during resistance training with varying training intensities on muscle outcomes in frail community-dwelling older adults: a randomized controlled trial

When older adults who don’t eat enough protein do strength training, adding protein helps them get much stronger — but if they already eat enough, extra protein doesn’t help much. So yes, training makes protein more effective, especially when you’re not getting enough.

Study: Effects of Whey Protein Supplementation Pre- or Post-Resistance Training on Muscle Mass, Muscular Strength, and Functional Capacity in Pre-Conditioned Older Women: A Randomized Clinical Trial

When older women did strength training and drank protein shakes, they built more muscle, got stronger, and walked faster than those who only did strength training without protein. So protein works better when you exercise.

Study: Resistance training, but not leucine, increased basal muscle protein synthesis and reversed frailty in older women consuming optimized protein intake.

When older women lifted weights and ate enough protein, their muscles got stronger and bigger, and they became less frail — but taking extra leucine pills didn’t help. This shows that lifting weights makes protein work better for your muscles.

Study: The effect of daily protein supplementation, with or without resistance training for 1 year, on muscle size, strength, and function in healthy older adults: A randomized controlled trial.

When older adults just drank protein shakes, their muscles didn't get stronger or bigger. But when they did heavy weight training along with the shakes, their muscles grew and got stronger. So, lifting weights helps protein work better.