The purpose of this research was to determine whether a loaded countermovement jump (LCMJ) could be enhanced if preceded by a set of half-squats with a 5-RM load. Ten subjects experienced with the squat exercise performed 2 sets of 5 LCMJ, 1 set of 5 squat reps with a 5-RM load, and 1 set of 5 LCMJ with 4 min rest between all sets. There was no significant difference between the first 2 sets of LCMJ, and the repeatability between these sets was high. However, the jump height for the set of LCMJ after the squat set was significantly greater (2.8%) than for the LCMJ set immediately preceding the squats. It was concluded that squats with a 5-RM load produce dramatic improvements in power performance. In addition, there was a significant correlation between performance enhancement from the squats and the 5-RM load. This suggests that stronger individuals may benefit more from resistance training exercises that utilize contrasting loads.
(C) 1998 National Strength and Conditioning Association