Even though people who trained one leg at a time ended up lifting heavier weights than those who trained both legs together, both groups ended up with the same muscle size and overall strength — so lifting heavier with one leg doesn’t automatically make you stronger overall.

Scientific Claim

Unilateral knee extension training allows for greater absolute loads to be used in the final weeks of a 12-week program compared to bilateral training in young women, yet this increased load does not translate to greater muscle growth or overall strength gains.

Original Statement

“A significant time × group interaction (p ≤ 0.05) for training load was observed... the UG trained with a significantly greater (p ≤ 0.05) loads in the last mesocycle.”

From study:Neuromuscular Adaptations to Unilateral vs. Bilateral Strength Training in Women

Evidence Quality Assessment

Claim Status

appropriately stated

Study Design Support

Design supports claim

Appropriate Language Strength

definitive

Can make definitive causal claims

Assessment Explanation

The RCT design with direct load tracking and outcome measures allows definitive claims about the dissociation between load and adaptation in this population.

Evidence from Studies

Supporting (0)

No supporting evidence found

Contradicting (1)

Neuromuscular Adaptations to Unilateral vs. Bilateral Strength Training in Women

Randomized Controlled Trial

Human

2016 Jul

Both types of training made women stronger and their muscles bigger about the same amount, and the unilateral training didn’t actually use heavier weights than the bilateral training, even though it might have seemed like it should.

Source Study

Neuromuscular Adaptations to Unilateral vs. Bilateral Strength Training in Women

Score: 47

DOI: 10.1519/jsc.0000000000001125

Similar Assertions

Whether you train one leg or both legs at once for 12 weeks, your legs get just as big and strong overall — the way you do the exercise doesn’t change how much muscle you build or how strong you become in general.

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Doing leg extensions one leg at a time for 12 weeks makes each leg stronger and more active when tested alone, better than doing both legs together — even though both methods improve overall leg strength similarly.

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If you lift light weights but push them until you can't do another rep, you can grow your muscles just as much as someone lifting heavy weights—so long as you're putting in the same total effort.

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To get stronger, it matters more how heavy the weight is than whether you push to your absolute limit—lifting heavier weights makes you stronger, no matter if you stop short of failure.

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Training one leg at a time makes it harder for both legs to work together at full power, while training both legs together makes them work better together — the way you train changes how your legs coordinate.

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