Resistance training enables the metabolic benefits of dietary protein intake for muscle maintenance and functional health in frail older adults, while protein supplementation alone does not enhance strength, muscle mass, or physical performance outcomes in this population unless baseline protein intake is below 0.8 g/kg/day.

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

When older women who were frail lifted weights and ate enough protein, their muscles got stronger and they felt less frail — but taking extra leucine pills didn't help at all. This shows that lifting weights is what makes protein work, not just eating more protein alone.

Study: Independent and combined effect of home-based progressive resistance training and nutritional supplementation on muscle strength, muscle mass and physical function in dynapenic older adults with low protein intake: A randomized controlled trial.

Lifting weights helped older adults get stronger and move better, even without protein shakes. Adding protein shakes didn’t make them any stronger or faster than just lifting weights alone.

Study: Protein Supplementation Augments Muscle Fiber Hypertrophy but Does Not Modulate Satellite Cell Content During Prolonged Resistance-Type Exercise Training in Frail Elderly.

In older adults who are weak, taking protein shakes alone doesn’t build muscle — but when they also do strength exercises, protein helps them grow stronger muscles. This study shows that protein + exercise works better than exercise alone.

Study: EFFECTS OF RESISTANCE TRAINING AND PROTEIN SUPPLEMENTATION ON CARDIORESPIRATORY, METABOLIC, IMMUNOLOGICAL, RENAL, AND BODY COMPOSITION VARIABLES IN THE ELDERLY

In older adults, lifting weights helps muscles get stronger and bigger from protein, but just drinking protein shakes without exercising doesn’t help much—unless they weren’t eating enough protein to begin with.