To grow your quads, biceps, and triceps best, it helps to stretch the muscle more during exercise—either by going all the way down or starting the movement early.
Scientific Claim
Training at a longer muscle length—through either full range of motion or partial range of motion in the initial part—is associated with optimal muscle growth in the quadriceps femoris, biceps brachii, and triceps brachii.
Original Statement
“evidence suggests that when training at a longer muscle length—through either pROM or fROM—some muscles, such as quadriceps femoris, biceps brachii, and triceps brachii, tend to experience optimal growth.”
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 'evidence suggests' and 'optimal growth,' implying causation and superiority, but the included studies' designs are unknown. Only an association can be claimed.
More Accurate Statement
“Training at a longer muscle length—through either full range of motion or partial range of motion in the initial part—is associated with greater muscle growth in the quadriceps femoris, biceps brachii, and triceps brachii.”
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 longer muscle length during resistance training consistently associates with greater hypertrophy in quadriceps, biceps, and triceps.
Whether longer muscle length during resistance training consistently associates with greater hypertrophy in quadriceps, biceps, and triceps.
What This Would Prove
Whether longer muscle length during resistance training consistently associates with greater hypertrophy in quadriceps, biceps, and triceps.
Ideal Study Design
A meta-analysis of 25+ RCTs comparing training at long vs. short muscle lengths (via ROM manipulation) in squats, leg extensions, bicep curls, and triceps extensions, measuring muscle thickness via ultrasound after 8–16 weeks, controlling for volume and load.
Limitation: Cannot isolate whether effects are due to stretch-mediated signaling or mechanical tension.
Randomized Controlled TrialLevel 1bWhether training at longer muscle length causes greater hypertrophy in these muscles.
Whether training at longer muscle length causes greater hypertrophy in these muscles.
What This Would Prove
Whether training at longer muscle length causes greater hypertrophy in these muscles.
Ideal Study Design
A double-blind RCT with 60 participants randomized to 12 weeks of training using either long-length ROM (full or initial partial) or short-length ROM (final partial) for squats, curls, and extensions, matched for volume, with muscle thickness measured at multiple sites.
Limitation: Cannot determine biological mechanisms or long-term sustainability.
Prospective Cohort StudyLevel 2bWhether habitual use of longer muscle length in training predicts greater hypertrophy in these muscles over time.
Whether habitual use of longer muscle length in training predicts greater hypertrophy in these muscles over time.
What This Would Prove
Whether habitual use of longer muscle length in training predicts greater hypertrophy in these muscles over time.
Ideal Study Design
A 2-year cohort study of 300 resistance-trained individuals tracking ROM usage in compound lifts via video, with muscle thickness measured quarterly via ultrasound.
Limitation: Cannot control for confounding variables like diet, sleep, or genetics.
Evidence from Studies
Supporting (1)
Which ROMs Lead to Rome? A Systematic Review of the Effects of Range of Motion on Muscle Hypertrophy
This study found that lifting weights through a full motion or starting the lift early (when muscles are stretched) helps your quads, biceps, and triceps grow better than lifting only partway at the end. So yes, stretching the muscle more during exercise helps it grow.