If older guys between 60 and 80 don’t use their legs for two weeks, they lose leg muscle and strength—but just two weeks of exercise plus drinking protein twice a day can bring it all back.

After older guys rest their legs for a bit, getting back to strength training with extra protein might help their leg muscles grow back stronger than before they took the break.

Older guys getting back into exercise after leg inactivity don’t seem to gain or lose muscle strength or size from taking ibuprofen every day, even if they’re also drinking protein shakes.

After drinking whey protein shakes every day for a week, older women’s muscles kept building up new protein even on days they didn’t exercise—collagen protein didn’t do this at all.

Middle-aged men doing strength training don't change their protein intake whether they take collagen, whey, or a placebo.

If older guys who are already active do full-body strength training three times a week for three months, they’ll get stronger legs and bigger leg muscles—even without adding extra protein to their diet.