Mixed

Protein or amino acid supplementation combined with resistance exercise training in older adults produces a positive but minor effect on whole-body lean mass growth, while having minimal and inconsistent effects on muscle mass, strength, or functional capacity.

If you are an older adult doing resistance training, adding protein or amino acid supplements will likely help you gain a small amount of lean body mass (roughly 0.2-0.8 kg more than exercise alone). However, do not expect significant increases in strength, muscle size, or physical function from the supplement alone; the exercise is doing the heavy lifting. This benefit is most noticeable in frail or sarcopenic individuals, whereas those who are obese may see little to no benefit.