Even if you only do squats, you still get almost as strong at leg extensions as someone who only does leg extensions—so squats aren’t useless for that movement.
Scientific Claim
Leg extension and back squat exercises produce similar increases in leg extension 3RM strength (+23.4% vs. +19.8%) in untrained young women after 8 weeks, indicating that compound movements may transfer strength benefits to isolation tasks when trained with sufficient volume and intensity.
Original Statement
“No between-group difference was observed in 3RM-LE increases (SQ = +19.8% vs. LE = +23.4%; p = 0.824).”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The null result is clearly reported with p-value, and the RCT design supports causal interpretation. However, 'produce similar increases' should be qualified as 'likely produce similar increases' due to lack of blinding confirmation.
More Accurate Statement
“Leg extension and back squat exercises likely produce similar increases in leg extension 3RM strength (+23.4% vs. +19.8%) in untrained young women after 8 weeks, indicating that compound movements may transfer strength benefits to isolation tasks when trained with sufficient volume and intensity.”
Evidence from Studies
Supporting (1)
Comparison of Muscle Hypertrophy and Strength Adaptations Induced by Back Squat and Leg Extension Resistance Exercises.
Even though one group only did squats and the other only did leg extensions, both groups got just as much stronger at doing leg extensions — meaning squats can help you get stronger at isolation moves too, if you train hard enough.