Differential Functional Adaptations to Short-Term Low-, Moderate-, and High-Repetition Weight Training

Abstract

Previously untrained young men (n = 38) were compared in terms of selected changes in leg function following 7 weeks of differential repetition exposures during heavy-resistance training. Subjects were randomly placed into 1 of 4 groups. Groups I, II, and III completed 3 workouts per week, including a warm-up and 4 sets of squats for a 3–5 repetitions maximum (3–5RM), 13–15RM, or 23–25RM, respectively. A fourth (control) group did not participate in formal physical training during this interim. Selected tests of leg function included dynamic constant external resistance (DCER) squat strength, isokinetic knee extension and flexion peak torque at both 60 and 300 × *S⁻¹, and vertical jump. Following the 7-week training period, both DCER squat strength and knee extension peak torque at 60 ·-S⁻¹ were significantly increased in all 3 treatment groups more (p < 0.01) than in the control group. In addition, squat strength was improved more in group I than in group III (p < 0.05). No significant differences (p > 0.05) were found between any of the 4 groups for changes in either vertical jump distance, knee extension and flexion peak torque at 300 ·-S⁻¹, or knee flexion peak torque at 60 ·*S⁻¹. These results indicate that short-term low-, moderate-, and high-repetition heavy-resistance squat training programs have little effect on jumping distance or high-velocity strength but do enhance DCER squat strength and maximal low-velocity knee extension strength. In addition, the low-repetition program appears to be superior to the high-repetition program for improving squat strength. The absence of improvements in vertical jump distance and fast-velocity isokinetic knee extension and flexion peak torque suggests that short-term DCER weight training, performed as described above, may have minimal direct impact on “explosive” physical activities for young men having limited training experience.