EXERCISE: Leg press
The leg press, regardless of design, has a preset motor pattern determined by the manufacturer. Very few people fall into what the manufacturer considers an “average person.”
Some evidence suggests the leg press makes athletes more prone to lower back problems, because at the bottom position, they are very deep into flexion – the knees get close to the chest, and many times the back is raised off the pad.
Because the leg press is built to optimize leverage and there is no stabilization involved, much more weight can be used than with a squat, making the compressive forces in this unnatural position with heavier weights potentially much more dangerous.
Brian Dobson, owner of Metroflex gym, says, “My daughter can leg press 800 pounds, yet she struggles to squat 115.” This is because trunk stability is no longer a factor. The end game is that the forces transmitted on leg muscles and joints are much greater than the body could naturally transmit during the squat.
So instead, opt for the full squat. Numerous studies show that not only are squats safe, but are a significant deterrent to knee injuries. Squats increase stability in the knee by increasing strength in the muscles around the joint, along with connective tissue.
Squatting prowess has been shown, in study after study, to correlate with sprinting and vertical jump ability. Not to mention the squat’s unrivaled ability to produce an anabolic hormonal spike which is beneficial for total-body muscle growth and fat-burning.
All this sounds great but what about working the actual muscle? A study by the University of North Dakota compared muscle recruitment during a leg press and a free weight barbell squat. The study used male and female subjects, both trained and untrained. With equivalent loads in both exercises, subjects’ electromyographic (EMG) activity was recorded from the lower back, glutes, vastus lateralis (VL) and hamstrings.
Across the board, the squat elicited significantly more EMG activity than did the leg press in the lower back, glutes and hamstrings. A significant difference in the quad (vastus lateralis) activity was not observed between the two exercises, but squats still had the upper hand.