Effects of standard and eccentric overload strength training in young women.

PURPOSE: According to the force-velocity relationship of human skeletal muscle, the maximal load one can lift is limited by the concentric movement phase, and the eccentric phase is always underloaded. In the present study, we hypothesized that acute exercise training using an eccentric overload compared with standard loading would lead to greater neuromuscular and strength adaptations.

METHODS: Sedentary women (age 20.9 yr) were tested for concentric and eccentric three-repetition maximum (3RM), maximal isokinetic eccentric and concentric and isometric force and associated EMG activity of selected thigh muscles before and after 7 consecutive days of exercise training of the left quadriceps. The exercise program was designed so that the total weight lifted was similar between the eccentric overload (EO, N = 10) and standard group (ST, N = 10), but EO exercised with about 50% greater eccentric load whereas the controls did not exercise (N = 10).

RESULTS: There was a 22% increase in the total weight lifted over 7 d. On the average, EOs compared with STs strength gains were approximately twofold greater. Changes in EMG paralleled the changes in muscle strength without changes in biceps femoris coactivity during knee extension.

CONCLUSION: Because the strength gains were achieved by exercising at low intensities and over a short time period, exercise prescription of eccentric overloading appears especially suitable for elders, individuals deconditioned due to an injury, and the chronically diseased.