Doing exercises through a full motion or starting the movement with a shorter motion (but not ending with it) helps your muscles grow more in your thighs and biceps than doing only the last part of the movement.
Scientific Claim
Full range of motion and partial range of motion performed in the initial part of the movement are associated with greater hypertrophy in the rectus femoris, vastus lateralis, biceps brachii, and distal brachialis compared to partial range of motion performed in the final part of the movement, with between-group effect sizes of 0.20–0.90.
Original Statement
“Full ROM and pROM performed in the initial part of the ROM elicited greater muscle hypertrophy of the rectus femoris, vastus lateralis, biceps brachii, and brachialis distal sites (between-groups ES: 0.20–0.90) than pROM performed in the final part of the ROM.”
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 uses language implying superiority ('elicited greater'), but the included studies' designs are unknown, so causation cannot be established. Only association is supported.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Systematic Review & Meta-AnalysisLevel 1aIn EvidenceWhether specific ROM patterns consistently associate with greater hypertrophy across diverse populations and training protocols.
Whether specific ROM patterns consistently associate with greater hypertrophy across diverse populations and training protocols.
What This Would Prove
Whether specific ROM patterns consistently associate with greater hypertrophy across diverse populations and training protocols.
Ideal Study Design
A systematic review and meta-analysis of at least 20 randomized controlled trials in healthy adults aged 18–40, comparing full ROM vs. initial partial ROM vs. final partial ROM during compound exercises (e.g., squats, bench press, bicep curls), with muscle thickness measured via ultrasound at 8–12 weeks, controlling for volume, intensity, and training experience.
Limitation: Cannot prove causation if included RCTs lack blinding or have high dropout rates.
Randomized Controlled TrialLevel 1bCausal effect of ROM position on hypertrophy in a controlled setting.
Causal effect of ROM position on hypertrophy in a controlled setting.
What This Would Prove
Causal effect of ROM position on hypertrophy in a controlled setting.
Ideal Study Design
A double-blind, randomized controlled trial of 60 healthy adults performing 12 weeks of supervised resistance training with matched volume and intensity, assigned to full ROM, initial partial ROM, or final partial ROM for leg and arm exercises, with muscle cross-sectional area measured via MRI at baseline and endpoint.
Limitation: Cannot generalize to untrained populations or long-term adherence.
Prospective Cohort StudyLevel 2bLong-term association between habitual ROM use and muscle growth in real-world settings.
Long-term association between habitual ROM use and muscle growth in real-world settings.
What This Would Prove
Long-term association between habitual ROM use and muscle growth in real-world settings.
Ideal Study Design
A 1-year prospective cohort of 200 resistance-trained individuals tracking their typical ROM use during training and measuring muscle hypertrophy via DEXA at 6 and 12 months, adjusting for diet, sleep, and training history.
Limitation: Cannot rule out confounding by training volume or intensity differences.
Evidence from Studies
Supporting (1)
Which ROMs Lead to Rome? A Systematic Review of the Effects of Range of Motion on Muscle Hypertrophy
The study found that doing exercises with a full motion or stopping early in the movement (not at the end) builds more muscle in the thighs and biceps than stopping late in the movement — which is exactly what the claim says.