When untrained men get stronger in a static leg press, the main reason is that their thigh muscle near the hip gets bigger and its fibers angle more, which helps push harder.
Scientific Claim
In previously untrained men, changes in isometric knee extension strength following 10 weeks of heavy resistance training are most strongly associated with increases in proximal vastus lateralis cross-sectional area and fascicle angle, explaining 27% of individual variability in strength gains.
Original Statement
“The change in isometric torque was best (although weakly) predicted by the linear combination of the change in proximal-region vastus lateralis (VL) CSA and fascicle angle (R² = 0.27, p < 0.05; AICc wi = 0.52)”
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 with no control group or randomization, so causal language is inappropriate. The claim correctly uses 'associated with' and reflects the statistical correlation found.
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 intentionally increasing proximal vastus lateralis CSA and fascicle angle through targeted training causes greater isometric strength gains than training without such focus.
That intentionally increasing proximal vastus lateralis CSA and fascicle angle through targeted training causes greater isometric strength gains than training without such focus.
What This Would Prove
That intentionally increasing proximal vastus lateralis CSA and fascicle angle through targeted training causes greater isometric strength gains than training without such focus.
Ideal Study Design
A double-blind RCT of 100+ previously untrained men aged 18–40, randomized to either standard heavy resistance training or training with additional exercises specifically designed to maximize proximal VL hypertrophy and pennation angle (e.g., long-range leg presses with slow eccentrics), measuring changes in proximal VL CSA via ultrasound and isometric knee extension torque over 10 weeks.
Limitation: Cannot isolate whether changes in fascicle angle are a cause or consequence of muscle growth.
Longitudinal Cohort StudyLevel 2bIn EvidenceThe consistent association between proximal VL CSA/fascicle angle changes and isometric strength gains across diverse populations and training protocols.
The consistent association between proximal VL CSA/fascicle angle changes and isometric strength gains across diverse populations and training protocols.
What This Would Prove
The consistent association between proximal VL CSA/fascicle angle changes and isometric strength gains across diverse populations and training protocols.
Ideal Study Design
A prospective cohort of 200+ untrained men and women aged 18–50 undergoing 10 weeks of standardized heavy resistance training, with serial ultrasound measurements of proximal VL CSA and fascicle angle and weekly isometric torque assessments.
Limitation: Cannot rule out confounding variables such as nutrition, sleep, or genetic factors.
Cross-Sectional StudyLevel 3Whether individuals with naturally larger proximal VL CSA and higher fascicle angles exhibit greater baseline isometric strength.
Whether individuals with naturally larger proximal VL CSA and higher fascicle angles exhibit greater baseline isometric strength.
What This Would Prove
Whether individuals with naturally larger proximal VL CSA and higher fascicle angles exhibit greater baseline isometric strength.
Ideal Study Design
A cross-sectional analysis of 300+ healthy adults aged 20–50, measuring proximal VL CSA and fascicle angle via ultrasound and comparing isometric knee extension torque across a wide range of values.
Limitation: Cannot determine if anatomical differences cause strength differences or vice versa.
Evidence from Studies
Supporting (1)
The study found that when untrained men got stronger in a knee extension test after 10 weeks of heavy lifting, the main reasons were that their thigh muscle got bigger and its fibers angled differently — and together, these two changes explained 27% of why some people got stronger than others.