The biggest reason people get stronger during dynamic leg movements after training isn’t just muscle growth—it’s how much their brain tells their thigh muscles to fire harder.
Scientific Claim
In previously untrained men, increases in quadriceps muscle activation (EMG:M) are more strongly associated with gains in concentric and eccentric strength than changes in muscle size or fascicle angle, with correlations of r = 0.51–0.56.
Original Statement
“The change in agonist muscle activation was the strongest predictor of the changes in maximum concentric and eccentric torque production (r = 0.51–0.56), and this relationship was strengthened when muscle size and fascicle angle were added to the predictive models”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The study design is observational and cannot prove causation. The claim correctly uses 'associated with' and reports correlation coefficients, which are the only valid inferences from this design.
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.
Randomized Controlled TrialLevel 1bThat enhancing quadriceps neural drive directly causes greater concentric/eccentric strength gains independent of muscle growth.
That enhancing quadriceps neural drive directly causes greater concentric/eccentric strength gains independent of muscle growth.
What This Would Prove
That enhancing quadriceps neural drive directly causes greater concentric/eccentric strength gains independent of muscle growth.
Ideal Study Design
A double-blind RCT of 100+ untrained men aged 18–40, randomized to heavy resistance training with or without neuromuscular electrical stimulation (NMES) to enhance quadriceps activation during training, measuring EMG:M, muscle CSA, and isokinetic torque at 60°/s over 10 weeks.
Limitation: NMES may induce muscle growth independently, confounding neural vs. structural effects.
Longitudinal Cohort StudyLevel 2bIn EvidenceWhether individuals with greater increases in EMG:M consistently show greater strength gains, even when muscle size changes are similar.
Whether individuals with greater increases in EMG:M consistently show greater strength gains, even when muscle size changes are similar.
What This Would Prove
Whether individuals with greater increases in EMG:M consistently show greater strength gains, even when muscle size changes are similar.
Ideal Study Design
A prospective cohort of 200+ untrained adults undergoing 10 weeks of standardized resistance training, with weekly EMG:M, CSA, and fascicle angle measurements, stratifying participants by EMG:M change quartiles to compare strength gains within similar CSA change groups.
Limitation: Cannot control for differences in motivation, fatigue, or motor learning.
Cross-Sectional StudyLevel 3Whether individuals with higher baseline EMG:M exhibit greater dynamic strength capacity.
Whether individuals with higher baseline EMG:M exhibit greater dynamic strength capacity.
What This Would Prove
Whether individuals with higher baseline EMG:M exhibit greater dynamic strength capacity.
Ideal Study Design
A cross-sectional analysis of 300+ healthy adults aged 20–50 with varying training histories, measuring EMG:M during maximal isokinetic contractions and comparing peak torque, controlling for CSA and age.
Limitation: Cannot determine if higher activation causes higher strength or if stronger individuals naturally activate more.
Evidence from Studies
Supporting (1)
The study found that when untrained men lifted heavy weights, the biggest reason they got stronger in movements like kicking or squatting was because their muscles fired more intensely—not just because their muscles got bigger. This matches the claim that muscle activation matters more than size for strength gains.