I recently came across an article (I think it was in the Journal of Strength and Conditioning research?) where the researchers asked “What type of exercise will elicit the biggest hormonal response, machines or free weights?” They chose the leg press and back squat to duel it out in a test of which could produce the most testosterone and growth hormone.
The study used a number of experienced lifters. On one day they performed six sets of ten reps of the leg press starting with 80% of 1 rep max (1RM). On another day, after plenty of rest, they returned to the lab to perform the squat workout, which was also six sets of ten reps, starting with 80% of 1RM. During each of these workouts, the participants were sporting a catheter inserted into their arms so their blood could be sampled quickly.
In a result that didn’t really surprise anyone, barbell squats produced significantly higher levels of testosterone and growth hormone. At the greatest difference, which occurred during the workout, testosterone was about 25% higher when performing full squats versus leg press. But the difference in growth hormone was huge! Squats produced a full 200% more growth hormone during the workout. Even thirty minutes after the workout, participants who performed squats still had 100% more growth hormone as when they performed the leg press. Cortisol levels also rose more after the squat workout, further confirming the squat workout was a fundamentally different physiological experience.
So I ask myself, is the leg press a bad exercise? No. Any exercise that results in a positive adaptation can’t be bad. The question is one of efficiency. We all want to get the best results possible, however most of us have limited time and energy to devote to training. So it makes sense to use your time and energy on exercises that provide the best bang for your buck. And is the leg press as effective as a full squat? Absolutely NOT!