In terms of managing sarcopenia, many studies have shown that physical activity (in particular resistance exercise) and specific nutrition interventions such as protein and amino acids supplementation can improve muscle mass and strength in older adults. Moreover, several drugs have been suggested to have an impact on muscle outcomes, with various levels of scientific evidence. In the present paper we have reviewed the evidence regarding the effect of some new metabolic agents (vitamin D, leucine, β-hydroxy β-methylbutyrate, citrulline malate, ornithine, isoflavones) on sarcopenia and muscular outcomes in older adults. For each metabolic agent, we have also discussed the biological plausibility of the described effect.