Differential effects of strength versus power training on bone mineral density in postmenopausal women: a 2-year longitudinal study
- 1Institute of Medical Physics, University of Erlangen, Erlangen, Germany
- 2Institute of Sports Science, University of Erlangen, Erlangen, Germany
- Dr S von Stengel, Institute of Medical Physics, University of Erlangen, Henkestr 91, 91052 Erlangen, Germany;
- Accepted 6 March 2007
- Published Online First 5 June 2007
Objectives: To investigate the effect of two different schemes of loading in resistance training on bone mineral density (BMD) and pain in pretrained postmenopausal women.
Methods: 53 pretrained women (mean (SD) age 58.2 (3.7) years) who carried out a mixed resistance and gymnastics programme were randomly assigned to a strength training (ST) or power training (PT) group. The difference between the two groups was the movement velocity during the resistance training (ST, 4 s (concentric)/4 s (eccentric); PT, explosive/4 s). Otherwise both groups carried out periodised progressive resistance training (10–12 exercises, 2–4 sets, 4–12 repetitions at 70–92.5% of the one-repetition maximum (2/week) for 2 years. Mechanical loading was determined with a force measuring plate during the leg press exercise. At baseline and after 2 years, BMD was measured at different sites with dual x-ray absorptiometry. Pain was assessed by questionnaire.
Results: Loading magnitude, loading/unloading rate, loading amplitude and loading frequency differed significantly (p<0.001) between the two groups. After 2 years, significant between-group differences were detected for BMD (PT, −0.3%; ST, −2.4%; p<0.05) and bone area (PT, 0.4%; ST, −0.9%; p<0.05) at the lumbar spine. At the hip, there was a non-significant trend in favour of the PT group. Also the incidence of pain indicators at the lumbar spine was more favourable in the PT group.
Conclusion: The results show that PT may be superior for maintaining BMD in postmenopausal women. Furthermore, PT was safe as it did not lead to increased injury or pain.
Competing interests: None.
- one-repetition maximum
- bone mineral density
- power training
- strength training