In dynapenic older adults with low protein intake, nutritional supplementation alone does not improve muscle strength or physical function beyond minor gains in gait speed, and when combined with resistance training, it provides no additional benefit compared to resistance training alone.

When older adults with weak muscles and low protein intake do resistance training, their muscles still cannot build new proteins fast enough to get stronger because the signals that tell muscles to grow are too weak. Adding more protein doesn't fix this because the muscles aren't responding to it. The muscles only get a little better at walking because walking uses existing muscle function, not new growth.