Leg Development Leg presses, a compound exercise, train all of the major leg muscles at once in a natural squatting movement. As a compound -- multi-joint -- exercise, leg presses require all the major muscles of your legs to work in coordination, which works your weakest muscles the most and increases joint stability. Perform leg presses before you do muscle isolation exercises. Compound exercises require greater concentration on form and should not be performed with fatigued muscles.