If you're new to lifting and using light weights, you need to push your muscles until they can't do another rep to grow them bigger—otherwise, even doing more reps won't help.

Scientific Claim

In untrained young men performing unilateral knee extensions, training with low loads (30% 1RM) to muscular failure increases quadriceps cross-sectional area by approximately 7.8% (ES: 0.45), while training without failure at the same load produces no significant hypertrophy (2.8%, ES: 0.15), indicating that high effort is necessary for muscle growth under low-load conditions when volume is equated.

Original Statement

“Quadriceps CSA increased significantly for HL-RF (8.1%, ES: 0.57), HL-RNF (7.7%, ES: 0.60), and LL-RF (7.8%, ES: 0.45), whereas no significant changes were observed in the LL-RNF (2.8%, ES: 0.15).”

From study:Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training

Evidence Quality Assessment

Claim Status

appropriately stated

Study Design Support

Design supports claim

Appropriate Language Strength

definitive

Can make definitive causal claims

Assessment Explanation

This is a randomized controlled trial with volume equated and direct MRI measurements of hypertrophy, allowing definitive causal claims within the studied population and protocol.

Evidence from Studies

Supporting (1)

Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training

Randomized Controlled Trial

Human

2022 Feb 1

When lifting light weights, you need to push until you can’t do another rep to grow your muscles—but if you’re lifting heavy weights, you don’t need to go all the way to failure to see gains.

Contradicting (0)

No contradicting evidence found

Source Study

Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training

Score: 54

DOI: 10.1519/JSC.0000000000003454

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