Comparison between twelve and six sets of high load leg extension on muscle strength

There are many studies about muscle strength after eccentric exercise. However, muscle strength after weight resistance exercise including the concentric and eccentric phases, which are usually performed in resistance training, has not been fully investigated. The purpose of the present study was to compare the effects of mid- and high-volume weight resistance exercise on muscle strength. Sixteen subjects were divided into a high-volume group who performed 12 sets (12SET, n=8) and a mid-volume group who performed 6 sets (6SET, n=8). They performed leg extension on the first day. The exercise load was 4~6 RM. The rest between sets was 3 minutes. Maximal voluntary contraction (MVC), isokinetic strength (30°/ sec.: ISOK30, 60°/ sec.: ISOK60, 150°/ sec.: ISOK150, 240°/ sec.: ISOK240), muscle soreness, and thigh circumference were measured before (PRE), after (POST), and 1 day, 2 day, 3 day, 5 day, and 7 day after exercise. The only significant effect was time in all measurements. Although MVC decreased at POST, it recovered to the level of PRE by1 day after exercise. ISOK150 and ISOK240 showed similar results to MVC. ISOK30 showed a lower value at 1 day after exercise. ISOK60 did not change throughout the experiment. Muscle soreness was higher at POST, 1 day and 2 days after exercise. Peak muscle soreness was higher for 12SET than for 6SET. Thigh circumference was higher at POST and 1 day after exercise. These results indicated that muscle damage was lower than previously reported after eccentric exercise. In addition, there was no difference between 12 sets and 6 sets of weight resistance exercise except for peak muscle soreness. Our results suggest that muscle strength after leg extension recovers by two days irrespective of whether 12 sets or 6 sets of high load leg extension are performed.