There is a little doubt that the leg press generates a quadriceps dominated contraction. Recently, Japanese scientests measured electromyographical activity in the medialis an dlateralis during the leg press. They measured narrow, normal and widestances, and the results were intriguing. REgardless of foor position, the EMG revealed that while both muscle sections were activated, the vastus medialis showed greater electrical activity tahn the vastud lateralis. The vastus medialis showed greates electrical activity when teh narrow stance was used. Messade: Alter your foot width to increase ot decrese action ont eh lateralis and medialis.
Conversely, the leg press produces little involvement in the hamstrings. Using EMG testing, scientists at teh American Sparts Medicine Institute found no co con traction of hamstrings and quadriceps during the horizonal leg press. To generate hamestring/glute contraction, the upper body must move toward the kneeds during a rep, as it does during a squat. Woth the horizonal leg press, hoever, the torso remains stationary. Though it does extend forward a bit in the 45-degree version, because the torso remains stationary agains and supported by the backrest, minimal hamstring involvement and adaptation as well.
To increse hamstring involvement, place your upper torso farther forward, approximating a squatting action. But this will not build up the hamstrings enough to balance front and rear thigh development.
