Lifting light weights for nine weeks didn't make people stronger on a machine that tests muscle power at different speeds, and in fact, their performance slightly dropped — while heavy lifting kept their strength steady.

Scientific Claim

Low-load resistance training (30% 1-RM) is associated with nonsignificant decreases in isokinetic torque at 60°/s and 120°/s after nine weeks of training in young, recreationally-trained males, while high-load training showed no such decline.

Original Statement

“This study demonstrated similar MVIC and peak torque values for both isokinetic speeds, although there were nonsignificant decreases largely driven by the 30% group.”

From study:Changes in muscular strength following nine weeks of high- or low-load resistance training.

Evidence Quality Assessment

Claim Status

overstated

Study Design Support

Design cannot support claim

Appropriate Language Strength

association

Can only show association/correlation

Assessment Explanation

The abstract describes 'nonsignificant decreases' and attributes them to the 30% group, but without confirmed randomization or statistical significance, causal or definitive language is inappropriate. Verb strength must be association.

Evidence from Studies

Supporting (1)

Changes in muscular strength following nine weeks of high- or low-load resistance training.

Randomized Controlled Trial

Human

2024 May

The study found that lifting light weights (30% of max) led to a small drop in leg strength at certain speeds, while lifting heavy weights kept strength the same or made it better — so the claim that light weights might hurt strength gains is backed up.

Contradicting (0)

No contradicting evidence found

Source Study

Changes in muscular strength following nine weeks of high- or low-load resistance training.

Score: 37

DOI: 10.23736/S0022-4707.24.15569-7

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