The Claim

In elderly men undergoing 12 weeks of resistance training, daily supplementation with 48 μg of vitamin D3 is associated with greater improvement in muscle quality (defined as strength per cross-sectional area) compared to a calcium-only placebo, despite no significant difference in muscle size or absolute strength gains between the two groups.

Source: Does vitamin-D intake during resistance training improve the skeletal muscle hypertrophic and strength response in young and elderly men? – a randomized controlled trial

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
53score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Correlation
1 study reviewed
In plain English

When older men lift weights for 12 weeks and take a daily vitamin D3 pill, their muscles get stronger relative to their size compared to men who only take calcium — even though their muscles don’t get bigger or stronger in absolute terms.

See the scientific wording

In elderly men undergoing 12 weeks of resistance training, daily supplementation with 48 μg of vitamin D3 is associated with greater improvement in muscle quality (strength per cross-sectional area) compared to calcium-only placebo, despite no difference in muscle size or absolute strength gains.

What the research says

1 study
  1. Study: Does vitamin-D intake during resistance training improve the skeletal muscle hypertrophic and strength response in young and elderly men? – a randomized controlled trial

    The study gave older men vitamin D and weight training, and while their muscles didn’t get bigger or stronger overall, they got stronger for their size — meaning their muscles worked better, which is exactly what the claim says.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.