Bone-Targeted Exercise Strategies to Reduce Fracture Risk in Men

High-intensity progressive resistance and impact training (HiRIT) is a well-tolerated program that may improve bone mineral density (BMD), body composition, physical function, and muscle strength and can reduce risk for fragility fracture in middle-aged and older men with osteopenia and osteoporosis, according to study results published in the Journal of Bone and Mineral Research.

Although there is evidence supporting exercise to reduce the risk for falls and fractures in older adults, there are reports that exercise has a limited effect on BMD and may even be hazardous for osteoporotic bone. The Lifting Intervention for Training Muscle and Osteoporosis Rehabilitation (LIFTMOR) study showed that 8-month supervised HiRIT program improved BMD, muscle strength, and physical function in postmenopausal women with low or very low bone mass, with no increased vertebral fracture risk.

The goal of the LIFTMOR for Men (LIFTMOR-M) trial was to explore the effects of 8 months of HiRIT or machine-based isometric axial compression exercise on determinants of osteoporotic fracture risk in middle-aged and older men with low BMD, compared with a matched control group.

The primary outcome was femoral neck areal BMD given elevated mortality with fragility fracture at this site. A series of common physical function tests related to fall risk were performed to examine mobility and dynamic balance, including timed up-and-go, 5-time sit-to-stand, and functional reach test. Furthermore, anthropometry, body composition, compliance, and adverse events were assessed.

The study cohort included 93 men who were randomly assigned to HiRIT (34 participants; mean age, 64.9 years; femoral neck T-score, -1.62±0.56), isometric axial compression exercise (33 participants; mean age, 69.0 years; femoral neck T-score, -1.77±0.54), or a control group with no changes to usual lifestyle (26 participants; mean age, 67.4 years; femoral neck T-score, -1.28±0.57).

Effects of HiRIT were superior to those of the control lifestyle for trochanteric (2.8%±0.8% vs -0.1%±0.9%, respectively; P =.024) and lumbar spine BMD (4.1%±0.7% vs 0.9%±0.8%, respectively; P =.003), but there were no significant between-group differences in percent change for femoral neck BMD. Furthermore, HiRIT improved broadband ultrasound attenuation (2.2%±0.7% vs -0.8%±0.9%, respectively; P =.009), stiffness index (1.6%±0.9% vs -2.0%±1.1%, respectively; P =.011), lean mass (1.5%±0.8% vs; -2.4%±0.9%, respectively; P =.002), timed up-and-go (P =.007), 5-time sit-to-stand compared with the control lifestyle (P <.001), and measures of muscle strength.

Effects of isometric axial compression exercise were superior to those of the control lifestyle for lean mass (0.8%±0.8% vs -2.4%±0.9%, respectively; P =.013) and 5-time sit-to-stand (-4.5%±1.6% vs 7.5%±2.0%, respectively; P <.001).

Comparing the 2 exercise interventions, HiRIT was superior to isometric axial compression exercise for lumbar spine BMD (4.1%±0.7% vs 2.0%±0.7%, respectively; P =.039), stiffness index (1.6%±0.9% vs -1.3%±0.9%, respectively; P =.025), and 5-time sit-to-stand (-10.7%±1.6% vs -4.5%±1.7%, respectively; P =.010).

There were no between-group differences in the number of falls; number of men who fell, sustained ≥1 fall, or had recurrent falls; or number of fragility fractures.

Supervised HiRIT was well accepted and tolerated with minimal adverse events. Compliance was 77.8%±16.6% for HiRIT (n=30) and 78.5%±14.8% for isometric axial compression exercises (n=30) and did not differ between groups (P =.872). Overall, 76.7% of HiRIT and 80.0% of isometric axial compression exercise participants had ≥70% compliance.

The researchers noted several limitations to the study, including failure to meet the target sample size for some analyses, the semirandomized controlled study design, and a sample limited to generally healthy men, as patients with comorbidities were excluded.

“[T]he novel findings of the current trial suggest that twice-weekly HiRIT is strongly indicated to reduce risk of fragility fracture in older men with low bone mass,” concluded the researchers.

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Reference

Harding AT, Weeks BK, Lambert C, Watson SL, Weis LJ, Beck BR. A comparison of bone-targeted exercise strategies to reduce fracture risk in middle-aged and older men with osteopenia and osteoporosis: LIFTMOR-M semi-randomized controlled trial [published online March 16, 2020]. J Bone Miner Res. doi: 10.1002/jbmr.4008