When teenage rugby players train one leg at a time on the leg press machine, they get much stronger in that single leg than when they train both legs together at the same time.

Scientific Claim

Unilateral leg press training is more effective than bilateral leg press training for improving unilateral lower body strength in adolescent male rugby players, producing a 20.2% increase (d = 0.81) compared to 12.4% (d = 0.45), indicating that training one leg at a time leads to greater strength gains on that side.

Original Statement

“The 5-RM UL LP also showed a significant main effect of time (F1, 16 = 115.6, p ≤ 0.001, = 0.88) and a significant interaction effect (F2, 16 = 39.62, p ≤ 0.001, = 0.83). Following training, BL (t6 = −10.74, p ≤ 0.01, ES = 0.45) and UL (t6 = −9.27, p ≤ 0.01, ES=0.81) groups experienced significant improvements in the 5-RM UL LP... the UL group had significantly greater strength increases than the BL group (p = 0.02).”

From study:The Effect of Unilateral and Bilateral Leg Press Training on Lower Body Strength and Power and Athletic Performance in Adolescent Rugby Players

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 comparison between groups and significant p-value (p=0.02) supports definitive causal language. The effect size difference is large and statistically robust.

Evidence from Studies

Supporting (1)

The Effect of Unilateral and Bilateral Leg Press Training on Lower Body Strength and Power and Athletic Performance in Adolescent Rugby Players

Randomized Controlled Trial

Human

2023 Mar

Training one leg at a time made the players stronger on that one leg more than training both legs together did, which is exactly what the claim says.

Contradicting (0)

No contradicting evidence found

Source Study

The Effect of Unilateral and Bilateral Leg Press Training on Lower Body Strength and Power and Athletic Performance in Adolescent Rugby Players

Score: 54

DOI: 10.5114/jhk/159626

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