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.

Scientific Claim

In healthy older women, the muscle protein synthetic response to whey protein is strongly correlated between rested and exercised legs, indicating a systemic anabolic effect rather than a localized one.

Original Statement

“There was an association with the acute MyoPS response between Rest and Exercise for both WP (r = 0.74, P = 0.0229) and CP (r = 0.98, P = 0.0002). There was an association with the integrated MyoPS response between Rest and Exercise for both WP (r = 0.93, P = 0.0034) and CP (r = 0.85, P = 0.003).”

From study:Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial.

Evidence Quality Assessment

Claim Status

appropriately stated

Study Design Support

Design supports claim

Appropriate Language Strength

association

Can only show association/correlation

Assessment Explanation

The study measured correlation (r-values), not causation, between legs. The verb 'is strongly correlated' is appropriate; causal language would overstate the finding.

Evidence from Studies

Supporting (0)

No supporting evidence found

Contradicting (1)

Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial.

Randomized Controlled Trial

Human

2020 Mar 1

The study found that whey protein helps muscles grow more when you exercise, but it didn’t check if the muscle growth in your exercised leg predicts growth in your resting leg—so we can’t say the effect is the same all over the body.

Source Study

Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial.

Score: 66

DOI: 10.1093/ajcn/nqz332

Similar Assertions

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.

87%

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.

82%

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.

79%

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.

77%

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.

75%