Doing full bicep curls might help you lift a little more weight in a max lift than doing half curls, but the difference is tiny and not very certain.
Scientific Claim
In resistance-trained individuals, full range of motion training (0°–140°) may be associated with slightly greater gains in one-repetition maximum (1RM) strength compared to partial range of motion training at long muscle lengths (0°–70°), with a trivial-to-small effect size (SMD = 0.17) and weak Bayesian evidence (BF = 1.95), supporting the principle of movement-specific adaptation.
Original Statement
“MVC at 100° (SMD = 0.24 and Bayes factor = 3.02) and 1RM (SMD = 0.17 and Bayes factor = 1.95) demonstrated greater but negligible improvements with fROM, with weak to moderate evidence supporting the hypothesis of differential effectiveness across interventions.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The small effect size and weak Bayes factor (BF=1.95) justify cautious language. The claim uses 'may be associated' and avoids causation, correctly reflecting the evidence strength and study limitations.
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 1aWhether fROM consistently leads to greater 1RM gains than pROMinitial across multiple RCTs in trained populations, with subgroup analysis by muscle group and training duration.
Whether fROM consistently leads to greater 1RM gains than pROMinitial across multiple RCTs in trained populations, with subgroup analysis by muscle group and training duration.
What This Would Prove
Whether fROM consistently leads to greater 1RM gains than pROMinitial across multiple RCTs in trained populations, with subgroup analysis by muscle group and training duration.
Ideal Study Design
A meta-analysis of all RCTs comparing fROM vs. pROMinitial (0°–70°) in resistance-trained adults, measuring 1RM as primary outcome, with at least 6 weeks of training, controlling for volume, intensity, and exercise type (e.g., curls, presses).
Limitation: Cannot determine if differences are due to neural adaptation or muscle growth.
Randomized Controlled TrialLevel 1bIn EvidenceWhether fROM causes greater 1RM strength gains than pROMinitial in trained individuals under controlled conditions.
Whether fROM causes greater 1RM strength gains than pROMinitial in trained individuals under controlled conditions.
What This Would Prove
Whether fROM causes greater 1RM strength gains than pROMinitial in trained individuals under controlled conditions.
Ideal Study Design
A double-blind, randomized, crossover RCT with 60+ resistance-trained adults, performing 12 weeks of unilateral preacher curls (fROM vs. pROMinitial), with 1RM tested pre/post using standardized protocols, blinded testers, and matched volume and intensity.
Limitation: Still cannot isolate whether strength gains are due to neural or structural changes.
Prospective Cohort StudyLevel 2bWhether individuals who habitually use fROM in training achieve greater 1RM gains over time than those using pROMinitial.
Whether individuals who habitually use fROM in training achieve greater 1RM gains over time than those using pROMinitial.
What This Would Prove
Whether individuals who habitually use fROM in training achieve greater 1RM gains over time than those using pROMinitial.
Ideal Study Design
A 2-year prospective cohort of 300+ resistance-trained lifters self-selecting fROM or pROMinitial training, with quarterly 1RM testing, controlling for training history, volume, and nutrition.
Limitation: Subject to self-selection bias and confounding lifestyle factors.
Animal Model StudyLevel 4Whether training through full vs. partial ROM alters neural drive or motor unit recruitment patterns in elbow flexors.
Whether training through full vs. partial ROM alters neural drive or motor unit recruitment patterns in elbow flexors.
What This Would Prove
Whether training through full vs. partial ROM alters neural drive or motor unit recruitment patterns in elbow flexors.
Ideal Study Design
A rat study with 40 animals, trained for 8 weeks with either full or partial elbow flexion resistance, measuring EMG activity, motor unit recruitment thresholds, and spinal reflex excitability.
Limitation: Cannot replicate human motor learning or voluntary effort.
Cross-Sectional StudyLevel 3Whether experienced lifters who prefer fROM have higher 1RM values than those who prefer pROMinitial, after matching for training age and volume.
Whether experienced lifters who prefer fROM have higher 1RM values than those who prefer pROMinitial, after matching for training age and volume.
What This Would Prove
Whether experienced lifters who prefer fROM have higher 1RM values than those who prefer pROMinitial, after matching for training age and volume.
Ideal Study Design
A cross-sectional study comparing 1RM elbow flexion strength in 100+ trained lifters (≥3 years experience) who primarily use fROM vs. pROMinitial, matched for age, sex, training volume, and muscle thickness.
Limitation: Cannot determine causality or direction of effect.
Evidence from Studies
Supporting (1)
The study found that lifting weights all the way through the full motion gave a tiny bit more strength gain than lifting only halfway, but the difference was so small it hardly matters — which is exactly what the claim says.