High-resistance versus variable-resistance training in older adults

Purpose: The purpose of this study was to compare the effects of high-resis tance (HR) training, 3 times.wk(-1) at 80% maximum strength (1RM) with 3 ti mes-wk(-1) variable-resistance (VR) training (once-weekly training at 80%, 65%, and 50% 1RM) in older adults. Methods: The study was a 6-month resista nce training intervention conducted in the Birmingham Alabama metropolitan area, and included healthy volunteer men and women over the age of 60. Twen ty-eight subjects were assigned randomly to two training groups. Eight volu nteers served as controls. Before and after 25 wk of training, body composi tion was measured by densitometry; strength by isometric tests; and difficu lty in performing daily activity tasks (DAT) by measuring heart rate, oxyge n uptake, electromyography, and perceived exertion. In addition, 1RM streng th was measured every 25 d throughout the 6 months of training. Repeated me asures ANOVA and paired t-tests with Bonferroni corrections for additive al pha were used to analyze the data. Results: The control group did not signi ficantly change in any study parameter. No significant change in body weigh t occurred for any group. However, the HR and VR groups increased fat free mass (FFM) similarly (1.8 kg and 1.9 kg, respectively). Both training group s increased strength significantly, without significant differences in chan ge. No significant change in oxygen uptake occurred during DAT. However, th ere was a significant time effect for heart rate and perceived exertion. Gr eater decrease in normalized integrated electromyography during the carry t ask was found in the VR group over the HR and control groups. Conclusion: D espite similar increases in strength and fat free mass, the VR group decrea sed difficulty of performing the carry task more than the HR group. These d ata suggest that larger improvements in DAT may be achieved if frequency of high-resistance training is less than 3 times.wk(-1).