When one leg got whey protein and exercise, the other leg (which didn’t exercise) still showed similar muscle-building activity—meaning the effect was happening all over the body, not just where the exercise happened.

With collagen protein, the muscle-building effect was almost identical in the exercised and non-exercised leg—unlike whey, which responded more strongly where exercise happened.

Whey protein made muscles grow faster, but it didn’t turn on the usual ‘growth switches’ in the cells—meaning it must be working through a different, unknown way.

Even though whey protein made muscles build faster, it didn’t change the usual ‘on/off’ switches in muscle cells that are supposed to control growth—suggesting other mechanisms are at play.

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.

When older women drink whey protein shakes, their muscles start repairing and growing faster—especially if they also do leg exercises—while collagen protein shakes don’t do much unless they exercise, and even then, it’s much weaker.