Influence of strength training variables on strength gains in adults over 55 years-old: A meta-analysis of dose–response relationships

Abstract

The importance of strength training to elderly individuals is well established. However, the dose-response relationship of the benefits of strength training in this population is unclear. The purpose of the study was to use meta-analysis to investigate the dose-response of the effects of strength training in elderly individuals. Fifteen studies with a total of 84 effect-sizes were included. The analyses examined the dose-response relationships of the following training variables 'intensity', 'number of sets', 'weekly frequency', and 'training duration' on strength improvement. The studies selected met the following inclusion criteria: (a) randomized controlled trials; (b) trained healthy subjects of both genders; (c) trained subjects aged 55 years or older; (d) strength increases were determined pre- and post-training; (e) use of similar strength evaluation techniques (strength determined by a repetition maximum test) and training routine (dynamic concentric-eccentric knee extension exercise to train the quadriceps muscle group). The effect-sizes were calculated using fixed and random effect models with the main effects determined by meta-regression. Many combinations of training variables resulted in strength increases. However meta-regression indicated only "training duration" had a significant dose-response relationship to strength gains (p=0.001). Over durations of 8-52 weeks, longer training durations had a greater effect on strength gains compared to shorter duration protocols. Resistive training causes strength gains in elderly individuals, provided the training duration is sufficiently long, regardless of the combination of other training variables.