If you do leg presses for 9 weeks, your legs will get stronger and bigger—even if you do it once or three times a week.
Scientific Claim
In trained men, resistance training using unilateral leg press 45° for 9 weeks significantly increases maximal strength (1RM) and quadriceps cross-sectional area (CSA), regardless of training frequency, indicating that the exercise and duration are sufficient to drive adaptation.
Original Statement
“All conditions effectively increased 1RM and CSA (p<0.001);”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The within-subject pre-post design with statistical significance (p<0.001) supports a definitive claim of adaptation to the training stimulus, as changes are measured within individuals over time.
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 1bCausal effect of unilateral leg press training on strength and hypertrophy in trained men compared to a no-training control.
Causal effect of unilateral leg press training on strength and hypertrophy in trained men compared to a no-training control.
What This Would Prove
Causal effect of unilateral leg press training on strength and hypertrophy in trained men compared to a no-training control.
Ideal Study Design
A parallel-group RCT with 60 trained men randomized to 9 weeks of unilateral leg press 45° (3x/week, volume matched) or no training, with 1RM and quadriceps CSA via MRI as primary outcomes, and blinding of assessors.
Limitation: Ethical and practical limitations prevent true no-training control in trained populations.
Prospective Cohort StudyLevel 2bLong-term association between consistent leg press training and strength/hypertrophy outcomes in trained men.
Long-term association between consistent leg press training and strength/hypertrophy outcomes in trained men.
What This Would Prove
Long-term association between consistent leg press training and strength/hypertrophy outcomes in trained men.
Ideal Study Design
A 2-year cohort tracking 100 trained men who perform unilateral leg press 3x/week, measuring 1RM and CSA quarterly, controlling for diet and other training.
Limitation: Cannot rule out confounding from other training or lifestyle factors.
Evidence from Studies
Supporting (1)
Effect of different training frequencies on maximal strength performance and muscle hypertrophy in trained individuals—a within-subject design
The study found that doing the leg press once or three times a week for 9 weeks both made trained men stronger and built more quad muscle — so how often you do it doesn’t matter as long as you do the exercise long enough.