After 8 weeks of lifting weights, whether you do chest and triceps together or alternate them with back and biceps, your arms and chest still get noticeably bigger.
Scientific Claim
An 8-week resistance training program using either synergist or nonsynergist schemes is associated with significant increases in muscle thickness of the triceps brachialis, biceps brachialis, and pectoralis major in recreationally trained men, regardless of exercise sequencing.
Original Statement
“Both groups displayed significant increases in muscle strength and thickness (NS and SN, p < 0.05), with no significant difference observed between the groups for the dependent variables assessed (all p > 0.05).”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The study reports within-group improvements but lacks confirmed randomization, so causal language like 'increases' is inappropriate. Only association can be claimed.
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 resistance training in general, regardless of scheme, consistently produces hypertrophy in these muscles across populations.
Whether resistance training in general, regardless of scheme, consistently produces hypertrophy in these muscles across populations.
What This Would Prove
Whether resistance training in general, regardless of scheme, consistently produces hypertrophy in these muscles across populations.
Ideal Study Design
Meta-analysis of 15+ RCTs measuring muscle thickness (ultrasound/DXA) in recreationally trained men after 6–12 weeks of any structured resistance training program, with standardized volume and intensity.
Limitation: Cannot isolate effects of exercise sequencing.
Randomized Controlled TrialLevel 1bCausal effect of resistance training (any scheme) on muscle hypertrophy in this population.
Causal effect of resistance training (any scheme) on muscle hypertrophy in this population.
What This Would Prove
Causal effect of resistance training (any scheme) on muscle hypertrophy in this population.
Ideal Study Design
Double-blind RCT with 60 recreationally trained men randomized to resistance training (3x/week, 10–20 sets/week) vs. no training for 8 weeks, measuring muscle thickness via ultrasound in triceps, biceps, and pecs.
Limitation: Does not address whether sequencing matters.
Prospective Cohort StudyLevel 2bLong-term association between consistent resistance training and muscle growth in real-world settings.
Long-term association between consistent resistance training and muscle growth in real-world settings.
What This Would Prove
Long-term association between consistent resistance training and muscle growth in real-world settings.
Ideal Study Design
1-year cohort tracking 100 recreationally trained men who begin resistance training, measuring monthly changes in muscle thickness via ultrasound, controlling for diet and sleep.
Limitation: Cannot control for adherence or training quality.
Evidence from Studies
Supporting (1)
A Comparison Between Synergist and Nonsynergist Resistance Training Schemes in Recreationally Trained Men.