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

Abstract

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.