The time course of changes induced by resistance training and detraining on muscular and physical function in older adults.

Background: It is generally recognised that the physical functioning of older adults is enhanced with resistance exercise. The aim of this study was to investigate the time course of changes in upper and lower body muscle strength and physical function in older individuals following a 16 week resistance training (RT) programme and a similar duration detraining (DET) period.
Methods: Forty-one inactive individuals (55 to 75 years) were randomly allocated in a RT group (n = 22; three sessions per week) and a control (CON) group (n = 19). Muscle strength was assessed with 10RM leg and bench press tests, while the Timed-Up-and-Go (TUG) test was used to measure functional mobility. The Bruce treadmill test determined the participants' submaximal endurance capacity. Data were analysed using mixed model repeated measures ANOVA and P < 0.05 was considered statistically significant.
Results: Main treatment effects were found for muscle strength (P < 0.001) and functional mobility (P < 0.05). Upper and lower body strength generally showed a statistically significant improvement after every 4 weeks in RT (the increase after 16 weeks being 7.3 ± 4.9 kg and 86.6 ± 44.4 kg, respectively; P < 0.001) while TUG performance (-0.2 ± 0.4 s; P < 0.05) and submaximal endurance capacity (0.7 ± 0.9 min; P < 0.001) only improved after 16 weeks. Although muscle strength decreased after DET, it was still better than at baseline. No significant improvements in any performance variable were observed in CON directly after the intervention period (0-16 weeks) (P > 0.05).
Conclusion: A 16-week RT programme has positive effects on both muscular and physical function in older adults, although the time course of these adaptations is different. While the gains in muscle strength and submaximal endurance capacity were not totally lost after DET, functional mobility was completely reversed. Older adults can be reassured that if the need arises to discontinue RT for a certain period they will still retain a large amount of their acquired muscle strength, as well as a degree of physical function such as submaximal endurance capacity. The association between leg strength and submaximal endurance capacity strengthens the notion that RT should be incorporated in training and rehabilitation programmes of ageing and frail older adults.