Effects of Jack Supplementation Combined with Resistance Training on Isokinetic Muscular Strength and Power, Anaerobic Power, and Urinary Testosterone: Epitestosterone Ratio in Young Males.

INTRODUCTION

This study investigated the effects of resistance training and Jack supplementation on isokinetic muscular strength and power, Wingate anaerobic power, and testosterone: epitestosterone (T/E) ratio in young males.

METHODS

Forty young males were weight-matched and assigned into four groups: control (C), jack (ElJ), resistance training (RT), and Jack plus resistance training group (ElJ & RT). Participants in ElJ and ElJ & RT groups consumed 200 mg Jack daily, whereas participants in the C and RT groups consumed placebo capsules daily for 8 weeks. Resistance training program which consisted of 10 different exercises was conducted three times per week for 8 weeks. Participants' isokinetic muscular strength and power, anaerobic power, and urinary TE ratio were measured before and after the intervention period. This is a randomized placebo-controlled intervention study. Paired -test and one-way analysis of variance were used for statistical analysis.

RESULTS

The mean average power of knee flexion at 300°/s in the RT and ElJ & RT groups was significantly ( < 0.05) higher in the posttest compared with pretest. Wingate relative peak power in the RT group increased significantly ( < 0.05) compared with respective pretest value, whereas peak power in the combined ElJ & RT group was significantly ( < 0.05) higher in posttest compared with pretest. There was no significant difference in T/E ratio between pre- and posttests in all the groups.

CONCLUSIONS

The prescribed resistance training program, either with or without ElJ supplementation, improved isokinetic power of the lower limb. Resistance training alone improved relative anaerobic power, whereas combined Jack and resistance training improved peak power output. ElJ consumption of 200 mg daily for 8 weeks did not affect the urinary T/E ratio.