Effectiveness of a progressive resistance training program on work productivity and muscular strength among adult males with mental retardation

This study was designed to investigate the effects of a 9-week progressive resistance-training program on work productivity and muscular strength among adult males with mental retardation (MR). Data were collected on: (a) work productivity using the simulated work tasks of hand-truck push and box stacking; (b) work productivity using "on-site" work tasks (assembly work, dishwashing, mail sorting, and custodian) in jobs that were held by the participants; and (c) muscular strength as determined by one repetition maximum lifts using Nautilus, Universal, and Icarian weight machines.;The research design used for this study was a single-subject ABA applied behavior analysis that was replicated for each of four adult males with MR age 25 to 29 years. The participants' performance levels were assessed once every week during the 5-week baseline, the 9-week treatment, and the 6-week retention periods. During the treatment period, participants were involved in a twice-a-week progressive resistance-training program using leg extension, leg curl, chest press, biceps curl, triceps extension, and abdominal curl weight-lifting exercises. Front-lying chest lifts using the participants' body resistance were used for strengthening back muscles. The 9-week intervention period was divided into 3 phases. The first phase lasted for a period of 2 weeks (4 sessions) and included 2 sets of 12 repetitions of each of the 6 strength-training exercises with low resistance of 30% to 40% of participants' 1-RM lifts. The second phase of the intervention lasted for a total of 3 weeks (6 sessions) and involved lifting 3 sets of 8 repetitions of each exercise with a moderate increase in the amount of resistance set at 50% to 60% of participants' 1-RM lift. The third and final phase of the lifting program was 4 weeks (8 sessions) and included 4 sets of 6 repetitions of lifting with an increased resistance of 70% to 80% of each participant's 1-RM lifts.;Data were collected and visually analyzed using the split middle technique. Visual analyses involved comparison of the participants' celeration and trend lines of the strength and work productivity data. Results indicated that participants showed improvements in both muscular strength and the simulated work tasks of box stacking and hand truck push. It was concluded that participation in a 9-week resistance-training program improved participants' muscular strength on the simulated work tasks. The results did not reveal significant improvements in productivity for the on-site work tasks as a result of increased strength. This may have been due to inadequate instrumentation for assessing productivity at participants' actual jobs. Recommendations for future studies are also provided.