Heavy resistance training provides short-term benefits on bone formation in well-functioning older adults.

Objectives: Maintained bone health is critical for independent living when aging. Currently, multimodal exercise regimes including weight-bearing exercises with impact are prescribed as optimal for maintaining bone health, while there is less consensus on the effects of resistance training at different intensities upon bone. Here we examined whether bone health was positively influenced by 1 year of supervised resistance training at two different intensities.

Methods: Older adults at retirement age (mean age: 66 ± 3 years, n = 451) were randomized to either 1 year of heavy resistance training (HRT), moderate intensity training (MIT) or a non-exercising control group (CON) in the LISA (LIve active Successful Aging) study. Bone mineral density (BMD) was assessed at whole body level, femoral neck, and the lumbar region of the spine (L1-L4) using Dual-energy X-ray absorptiometry (DXA). Bone degradation and formation were evaluated with blood C-terminal telopeptide of type I collagen (CTX) and procollagen type I N-propeptide (PINP). Dephosphorylated uncarboxylated matrix Gla-protein (dp-ucMGP) was used as a biomarker of functional vitamin K status. Participants were assessed at baseline, immediately following the intervention (year 1), and at longitudinal follow-ups at years 2 and 4. Two-way mixed model ANOVAs were used to assess group differences at all time points.

Results: At the 4-year follow-up n = 329 participants (58 % women) remained in the study. BMD was not influenced by training and decreased across all groups over the 4 years for total body (F_3,977 = 4.617, p = 0.003, η² = 0.01) and femoral neck both in the dominant (F_3,893 = 45.135, p < 0.001, η² = 0.13) and non-dominant leg (F_3,896 = 33.821, p < 0.001, η² = 0.10). Independent of group, CTX increased (F_3,932 = 47.434, p < 0.001, η² = 0.13) over the 4 years. HRT resulted in an increased bone formation (PINP rise) only after the first year with systematic training (t(936) = 3.357, p = 0.04), and it was more pronounced than in CON (t(312) = 2.494, p = 0.04). Plasma dp-ucMGP remained unaltered over time in all groups. In general, women had significantly lower BMD and higher levels of CTX and PINP compared to men.

Conclusion: We demonstrated that 1 year of heavy resistance training positively influenced short-term bone formation in well-functioning older adults, although the effect was not maintained at long-term follow ups. These minor changes in bone biomarkers were not reflected in changes in BMD measured with DXA.

Trial registration: clinicaltrials.gov (NCT02123641).