Use It Or Lose It: What Happens To Bone When High-Intensity Exercise Ceases Or Continues?

Abstract

The LIFTMOR trial was the first to show a high-intensity resistance and impact training program (HiRIT) was safe and efficacious for improving bone and physical function in postmenopausal women with low to very low bone mass. While results were promising, the long-term efficacy and safety of HiRIT outside an RCT setting was unknown. PURPOSE: The primary aim of the current study was to evaluate the effects of continuing or ceasing HiRIT on bone mineral density (BMD) and physical function of LIFTMOR trial participants. METHODS: We report a retrospective observational study of LIFTMOR trial participants. Three years after completion of the LIFTMOR trial, participants in the HiRIT arm of the trial underwent a single testing session. Participants were allocated to one of two groups according to either ongoing HiRIT participation (compliance >25%; HiRIT-HiRIT), or cessation of HiRIT (HiRIT-CON) after LIFTMOR. The LIFTMOR testing protocol was employed, including; BMD at the lumbar spine (LS) and femoral neck (FN), back extensor strength (BES), lower extremity strength (LES), functional reach test (FRT), timed up-and-go test (TUG), five times sit-to-stand (FTSTS) and maximal vertical jump (VJ). Data were analysed using repeated measures ANCOVA comparing final LIFTMOR outcomes to 3 year outcomes. RESULTS: Twenty-three women (HiRIT-HiRIT, n = 7; 64 ± 4 yr, 159.4 ± 6.5 cm, 67.0 ± 7.2 kg and HiRIT-CON, n = 16; 65 ± 4 yr, 161.8 ± 5.9 cm, 61.9 ± 9.5 kg) participated in follow-up testing 3.2 ± 0.6 yrs post-LIFTMOR. There were no characteristic differences between the follow up sample and the LIFTMOR sample at baseline. Significant ongoing gains in BMD were apparent in HiRIT-HiRIT compared with HiRIT-CON at the LS (8.63 ± 5.29% vs 2.18 ± 5.65%, p = 0.042) and FN (3.67 ± 4.45% vs 2.85 ± 5.79%, p = 0.014), while the HiRIT-CON group maintained BMD benefits from the LIFTMOR intervention. Between-group differences in functional outcomes favoured HiRIT-HiRIT but did not reach significance. No injuries were reported. CONCLUSION: Postmenopausal women with low bone mass continuing HiRIT over a 4 year period continued to improve bone mass, while those ceasing HiRIT maintained the gains achieved from 8 months of HiRIT 3 years previously. HiRIT exercise appears to be a highly effective therapy to reduce risk of osteoporotic fracture by improving bone mass.