Study analysis · Journal of Strength and Conditioning Research · 2023
Doing partial reps might actually make your muscles bigger—here’s the shocking twist.
Lifting weights all the way isn’t always best—sometimes stopping early, especially at the start or middle, makes your muscles grow more.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at lots of other studies and found that using full or partial arm/leg movements during workouts might be linked to bigger muscles in some places — but we don’t know if the original studies were fair tests, so we can’t say for sure that one way of moving causes bigger muscles.
What’s the bottom line?
This study looked at whether lifting weights all the way up and down, or just partway, makes muscles grow more. It found that lifting through the full motion or starting the lift and stopping early (but not ending early) helps muscles grow bigger in some areas.
How strong is this study?
We can’t tell how good the original studies were because the abstract doesn’t say if they used random assignment or kept people blind — like not knowing which workout they got. That means we have to be careful trusting the results too much.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
0 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control groupno control group
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
31 / 100
- P-valuesno p-values reported
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 528 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
This design cannot establish causation — the findings describe an association, not a cause. Randomization, blinding, and control group status are unknown in the included studies; therefore, causation cannot be established.
Key takeaways
- 01
Full or early partial lifts: bigger muscles in quads, biceps, and brachialis (0.20–0.90 effect).
- 02
Full lifts: bigger glutes and adductors (0.24–0.25).
- 03
Early partial lifts: bigger top part of quads (0.35–0.38).
- 04
Middle partial lifts: bigger triceps (1.21).
- 05
Yes — effect sizes like 1.21 for triceps suggest a strong practical difference; even smaller effects (0.20+) suggest meaningful differences for muscle growth.
Surprising findings
- Partial ROM in the middle of the movement produced the largest effect size (1.21) for triceps hypertrophy—greater than full ROM.Most trainers preach full range for everything; this shows a mid-range partial can be dramatically more effective for triceps growth.
- Initial partial ROM produced greater proximal rectus femoris hypertrophy than full ROM (ES: 0.35–0.38).It’s counterintuitive that doing less of the movement (starting partial) would outperform full ROM for a specific muscle region.
Practical takeaways
For quads and biceps: Combine full ROM with initial partial reps (e.g., squat to 90°, then full squat). For triceps: Focus on mid-range partials (e.g., skullcrushers from 90° to 45°).
This is based on a systematic review of 11 studies, but full methodology and risk of bias are unknown.
low confidenceWhy this study matters
Full ROM vs. Early Partial ROM: The Muscle Growth Secret
Full range of motion and partial reps done in the initial part of the movement led to greater hypertrophy in the rectus femoris, vastus lateralis, biceps brachii, and distal brachialis (ES: 0.20–0.90) compared to partial reps at the end. Training at longer muscle lengths—like stretching the muscle early—boosts growth in these muscles.
Most people think full reps are always better, but this shows starting with a shortened range can be just as effective—or even better—for certain muscles.
Triceps Grow Best in the Middle—Not Full Range
Partial ROM in the middle of the movement produced significantly greater triceps hypertrophy than full ROM, with an effect size of 1.21—the largest in the study.
This flips the script: doing full arm extensions might be missing the sweet spot. The middle portion is where the triceps get the most growth stimulus.
Your Glutes Need Full ROM—But Only If You’re Not Ending Early
Full ROM outperformed final-part partial ROM for gluteus maximus and adductors (ES: 0.24–0.25), suggesting full squats or hip thrusts are better than just locking out at the top.
People often think glute growth comes from squeezing at the top—but this says the stretch at the bottom matters more.
The Proximal Quad Mystery: Why Starting Partial Beats Full ROM
Initial partial ROM produced greater hypertrophy in the proximal (upper) rectus femoris than full ROM (ES: 0.35–0.38), suggesting the top half of leg extensions may target the upper quad better.
This challenges the idea that full motion = uniform growth. Different parts of the same muscle respond differently to ROM.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at whether lifting weights all the way up and down, or just partway, makes muscles grow more. It found that lifting through the full motion or starting the lift and stopping early (but not ending early) helps muscles grow bigger in some areas.
Research results
Full or early partial lifts: bigger muscles in quads, biceps, and brachialis (0.20–0.90 effect). Full lifts: bigger glutes and adductors (0.24–0.25). Early partial lifts: bigger top part of quads (0.35–0.38). Middle partial lifts: bigger triceps (1.21).
What this means - more context
Yes — effect sizes like 1.21 for triceps suggest a strong practical difference; even smaller effects (0.20+) suggest meaningful differences for muscle growth.
To systematically review the effects of full versus partial range of motion on muscle hypertrophy and identify optimal ROM patterns for muscle growth.
A systematic review of 11 studies found that full ROM and partial ROM performed in the initial part of the movement led to greater hypertrophy in the rectus femoris, vastus lateralis, biceps brachii, and distal brachialis compared to partial ROM in the final part. Full ROM also produced greater hypertrophy in the gluteus maximus and adductors than final-part partial ROM. Initial partial ROM resulted in greater proximal rectus femoris hypertrophy than full ROM, and middle-part partial ROM yielded greater triceps brachii hypertrophy than full ROM. Training at longer muscle lengths (via full or initial partial ROM) was associated with optimal growth in quadriceps, biceps, and triceps.
Methods Used
Systematic review of 11 studies; effect sizes (ES) were calculated from included studies. Methodology details not available in abstract.
Main Finding
Full ROM and initial partial ROM produced greater hypertrophy than final partial ROM in rectus femoris, vastus lateralis, biceps brachii, and distal brachialis (ES: 0.20–0.90); full ROM outperformed final partial ROM in gluteus maximus and adductors (ES: 0.24–0.25); initial partial ROM showed greater proximal rectus femoris hypertrophy than full ROM (ES: 0.35–0.38); middle partial ROM produced greater triceps brachii hypertrophy than full ROM (ES: 1.21). Training at longer muscle lengths optimizes growth in quadriceps, biceps, and triceps.
Confidence Level
Limited - based on abstract only, full methodology not available
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •No information on study quality, risk of bias, or randomization in included studies
- •Effect sizes reported but confidence intervals and p-values not mentioned
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Partial ROM in the middle of the movement produced the largest effect size (1.21) for triceps hypertrophy—greater than full ROM.
Most trainers preach full range for everything; this shows a mid-range partial can be dramatically more effective for triceps growth.
Practical Takeaways
For quads and biceps: Combine full ROM with initial partial reps (e.g., squat to 90°, then full squat). For triceps: Focus on mid-range partials (e.g., skullcrushers from 90° to 45°).
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 528 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Human Meta-Analysis
Subject
Lower probability
on the GRADE evidence scale
This study looked at lots of other studies and found that using full or partial arm/leg movements during workouts might be linked to bigger muscles in some places — but we don’t know if the original studies were fair tests, so we can’t say for sure that one way of moving causes bigger muscles.
Weaknesses
- Full methodology not available - based on abstract only
- Randomization status of included studies unknown
- Blinding status of included studies unknown
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
This study looked at whether lifting weights all the way up and down, or just partway, makes muscles grow more. It found that lifting through the full motion or starting the lift and stopping early (but not ending early) helps muscles grow bigger in some areas.
Research results
Full or early partial lifts: bigger muscles in quads, biceps, and brachialis (0.20–0.90 effect). Full lifts: bigger glutes and adductors (0.24–0.25). Early partial lifts: bigger top part of quads (0.35–0.38). Middle partial lifts: bigger triceps (1.21).
What this means - more context
Yes — effect sizes like 1.21 for triceps suggest a strong practical difference; even smaller effects (0.20+) suggest meaningful differences for muscle growth.
To systematically review the effects of full versus partial range of motion on muscle hypertrophy and identify optimal ROM patterns for muscle growth.
A systematic review of 11 studies found that full ROM and partial ROM performed in the initial part of the movement led to greater hypertrophy in the rectus femoris, vastus lateralis, biceps brachii, and distal brachialis compared to partial ROM in the final part. Full ROM also produced greater hypertrophy in the gluteus maximus and adductors than final-part partial ROM. Initial partial ROM resulted in greater proximal rectus femoris hypertrophy than full ROM, and middle-part partial ROM yielded greater triceps brachii hypertrophy than full ROM. Training at longer muscle lengths (via full or initial partial ROM) was associated with optimal growth in quadriceps, biceps, and triceps.
Methods Used
Systematic review of 11 studies; effect sizes (ES) were calculated from included studies. Methodology details not available in abstract.
Main Finding
Full ROM and initial partial ROM produced greater hypertrophy than final partial ROM in rectus femoris, vastus lateralis, biceps brachii, and distal brachialis (ES: 0.20–0.90); full ROM outperformed final partial ROM in gluteus maximus and adductors (ES: 0.24–0.25); initial partial ROM showed greater proximal rectus femoris hypertrophy than full ROM (ES: 0.35–0.38); middle partial ROM produced greater triceps brachii hypertrophy than full ROM (ES: 1.21). Training at longer muscle lengths optimizes growth in quadriceps, biceps, and triceps.
Confidence Level
Limited - based on abstract only, full methodology not available
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •No information on study quality, risk of bias, or randomization in included studies
- •Effect sizes reported but confidence intervals and p-values not mentioned
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Surprising Findings
Partial ROM in the middle of the movement produced the largest effect size (1.21) for triceps hypertrophy—greater than full ROM.
Most trainers preach full range for everything; this shows a mid-range partial can be dramatically more effective for triceps growth.
Practical Takeaways
For quads and biceps: Combine full ROM with initial partial reps (e.g., squat to 90°, then full squat). For triceps: Focus on mid-range partials (e.g., skullcrushers from 90° to 45°).
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 528 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Human Meta-Analysis
Subject
Lower probability
on the GRADE evidence scale
This study looked at lots of other studies and found that using full or partial arm/leg movements during workouts might be linked to bigger muscles in some places — but we don’t know if the original studies were fair tests, so we can’t say for sure that one way of moving causes bigger muscles.
Weaknesses
- Full methodology not available - based on abstract only
- Randomization status of included studies unknown
- Blinding status of included studies unknown
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
We can’t tell how good the original studies were because the abstract doesn’t say if they used random assignment or kept people blind — like not knowing which workout they got. That means we have to be careful trusting the results too much.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
0 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control groupno control group
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
31 / 100
- P-valuesno p-values reported
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 528 / 100
Probability of being correct
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
This design cannot establish causation — the findings describe an association, not a cause. Randomization, blinding, and control group status are unknown in the included studies; therefore, causation cannot be established.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
3 videos from 2 different creators cite this study, drawing 3 claims from it.
- Very strong evidence
Randomized or controlled trials support this claim, alongside consistent supporting evidence.
Evidence
- Very strong evidence
Randomized or controlled trials support this claim, alongside consistent supporting evidence.
Evidence
Authored by
6 researchersIf this is your work, this is how we attribute it on Fit Body Science. Witalo Kassiano is listed as the lead author.
- Universidade Estadual de Londrina
Cited in 25 claims · 4 videos
- Universidade Estadual de Londrina
Cited in 16 claims · 3 videos