Daily protein plus lifting shifts the biology of age-related muscle loss

Sarcopenia, the progressive loss of muscle mass, strength and function with age, is one of the biggest threats to independence and quality of life in older adults. Resistance exercise and protein intake are each known levers, but the more interesting question is whether they work synergistically, amplifying each other's effects on the underlying biology rather than just adding up. Blood biomarkers such as myostatin and IGF-1 offer a window into whether muscle is being told to waste or to grow, which is why this review looked beneath the functional outcomes to the signalling itself.

The authors systematically searched PubMed, Scopus, ScienceDirect and Cochrane databases for studies published between 2019 and 2025, admitting only randomised controlled trials in humans published in English, Spanish or French. Risk of bias was assessed following the Cochrane Handbook, and the review was registered on PROSPERO. Seven trials met the criteria, totalling 260 participants. The interventions of interest combined resistance exercise three times per week at 60 to 80% of one-repetition maximum with daily protein supplementation of at least 15 g, mainly from dairy sources, and outcomes spanned both blood biomarkers and functional measures.

The combined approach shifted the biochemical picture in a favourable direction. Markers that suppress muscle growth or signal inflammation fell, including myostatin, activin and IL-6, while markers associated with muscle building and inflammation control rose, including IGF-1, follistatin and IL-10. These biochemical shifts were accompanied by tangible functional results: gains in muscle strength, fat-free mass and muscle fibre cross-sectional area. The authors note real variation between trials in duration and sample size, but conclude the combination is a promising and clinically applicable strategy for preventing and treating sarcopenia.

That resistance training builds muscle in older adults is well established, as is protein's supporting role; this review's contribution is tying the combination to a coherent biomarker signature, suggesting the pairing acts on the machinery of muscle regulation itself. The evidence base remains small, with only seven trials and 260 people in total, and the studies differed enough in design that the optimal protein dose, source and training programme are still open questions. Whether these biomarker shifts translate into fewer falls, less frailty or longer independence over years is beyond what these trials can show.

If you are past middle age and thinking about protecting your muscle, this is a reason to see protein and lifting as partners rather than alternatives: the trials reviewed here paired them, and both the blood chemistry and the strength outcomes moved together. The protein amounts involved were modest, at least 15 g daily on top of normal eating, mostly from dairy, and the training was structured resistance work rather than casual activity. The small size of the evidence base means the details are still being worked out, but the direction of travel is consistent and encouraging.