If you're a regular gym-goer, doing workouts that pair similar muscle groups together (like two push exercises) or alternating push and pull exercises both work just as well to build strength and muscle size over 8 weeks.
Scientific Claim
In recreationally trained men, both synergist and nonsynergist resistance training schemes are associated with similar increases in muscle strength (as measured by 1RM bench press and lat pull-down) and muscle thickness (in triceps brachialis, biceps brachialis, and pectoralis major) after an 8-week intervention, suggesting neither scheme provides a clear advantage for these outcomes.
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 abstract and plain language summary use causal language like 'benefit from' and 'effective for', but without confirmed randomization, causation cannot be established. 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 synergist vs. nonsynergist resistance training schemes produce statistically different effects on muscle strength and hypertrophy across multiple high-quality RCTs in recreationally trained men.
Whether synergist vs. nonsynergist resistance training schemes produce statistically different effects on muscle strength and hypertrophy across multiple high-quality RCTs in recreationally trained men.
What This Would Prove
Whether synergist vs. nonsynergist resistance training schemes produce statistically different effects on muscle strength and hypertrophy across multiple high-quality RCTs in recreationally trained men.
Ideal Study Design
A meta-analysis of at least 10 randomized, double-blind, controlled trials comparing synergist (e.g., push/push, pull/pull) and nonsynergist (e.g., push/pull) resistance training schemes in 18–35-year-old recreationally trained men, with standardized volume (10–20 sets/week per muscle group), intensity (70–85% 1RM), and duration (6–12 weeks), using DXA or ultrasound for muscle thickness and 1RM testing as primary outcomes.
Limitation: Cannot establish mechanisms or account for individual adherence variability across studies.
Randomized Controlled TrialLevel 1bCausal effect of synergist vs. nonsynergist training on muscle strength and hypertrophy in recreationally trained men, assuming proper randomization and blinding.
Causal effect of synergist vs. nonsynergist training on muscle strength and hypertrophy in recreationally trained men, assuming proper randomization and blinding.
What This Would Prove
Causal effect of synergist vs. nonsynergist training on muscle strength and hypertrophy in recreationally trained men, assuming proper randomization and blinding.
Ideal Study Design
A double-blind, randomized controlled trial with 100+ recreationally trained men (age 18–35, 1–5 years experience) assigned to either synergist (push/push, pull/pull) or nonsynergist (push/pull) training for 12 weeks, with matched volume, frequency, and intensity; muscle thickness measured via ultrasound and strength via 1RM testing; outcome assessors blinded to group assignment.
Limitation: Cannot eliminate all confounding lifestyle factors like diet or sleep.
Prospective Cohort StudyLevel 2bLong-term association between training scheme preference and sustained gains in strength and muscle mass in real-world settings.
Long-term association between training scheme preference and sustained gains in strength and muscle mass in real-world settings.
What This Would Prove
Long-term association between training scheme preference and sustained gains in strength and muscle mass in real-world settings.
Ideal Study Design
A 1-year prospective cohort tracking 200 recreationally trained men who self-select into either synergist or nonsynergist training routines, measuring monthly changes in 1RM and muscle thickness via ultrasound, controlling for diet, sleep, and training volume.
Limitation: Cannot rule out selection bias or confounding by personal preference or motivation.
Cross-Sectional StudyLevel 3Correlation between current training pattern and existing muscle size/strength in a population.
Correlation between current training pattern and existing muscle size/strength in a population.
What This Would Prove
Correlation between current training pattern and existing muscle size/strength in a population.
Ideal Study Design
A cross-sectional survey of 500 recreationally trained men measuring self-reported training scheme (synergist vs. nonsynergist) and correlating it with current 1RM and muscle thickness via ultrasound, controlling for age, experience, and protein intake.
Limitation: Cannot determine direction of causality or changes over time.
Evidence from Studies
Supporting (1)
A Comparison Between Synergist and Nonsynergist Resistance Training Schemes in Recreationally Trained Men.