Exercise training in obese older adults prevents increase in bone turnover and attenuates decrease in hip bone mineral density induced by weight loss despite decline in bone-active hormones

Abstract

Weight loss therapy to improve health in obese older adults is controversial because it causes further bone loss. Therefore, it is recommended that weight loss therapy should include an intervention such as exercise training (ET) to minimize bone loss. The purpose of this study was to determine the independent and combined effects of weight loss and ET on bone metabolism in relation to bone mineral density (BMD) in obese older adults. One-hundred-seven older (age >65 years) obese (body mass index [BMI] ≥ 30 kg/m(2) ) adults were randomly assigned to a control group, diet group, exercise group, and diet-exercise group for 1 year. Body weight decreased in the diet (-9.6%) and diet-exercise (-9.4%) groups, not in the exercise (-1%) and control (-0.2%) groups (between-group p < 0.001). However, despite comparable weight loss, bone loss at the total hip was relatively less in the diet-exercise group (-1.1%) than in the diet group (-2.6%), whereas BMD increased in the exercise group (1.5%) (between-group p < 0.001). Serum C-terminal telopeptide (CTX) and osteocalcin concentrations increased in the diet group (31% and 24%, respectively), whereas they decreased in the exercise group (-13% and -15%, respectively) (between-group p < 0.001). In contrast, similar to the control group, serum CTX and osteocalcin concentrations did not change in the diet-exercise group. Serum procollagen propeptide concentrations decreased in the exercise group (-15%) compared with the diet group (9%) (p = 0.04). Serum leptin and estradiol concentrations decreased in the diet (-25% and -15%, respectively) and diet-exercise (-38% and -13%, respectively) groups, not in the exercise and control groups (between-group p = 0.001). Multivariate analyses revealed that changes in lean body mass (β = 0.33), serum osteocalcin (β = -0.24), and one-repetition maximum (1-RM) strength (β = 0.23) were independent predictors of changes in hip BMD (all p < 0.05). In conclusion, the addition of ET to weight loss therapy among obese older adults prevents weight loss-induced increase in bone turnover and attenuates weight loss-induced reduction in hip BMD despite weight loss-induced decrease in bone-active hormones.

Trial registration: ClinicalTrials.gov NCT00146107.

Figure 1

Changes from baseline in body weight (A) and bone mineral density at the total hip (B), femoral neck (C) and trochanter (D) in obese older adults during the 1-year interventions. Values are mean ± SE. *P<0.05 for the comparison of the value from baseline, as calculated with the use of mixed-model repeated measures analyses of variance. ^†P<0.05 for the comparison of the value from control group, ^‡P<0.05 for the comparison of the value from diet group, ^§P<0.05 for the comparison of the value from exercise group, as all calculated with the use of mixed-model repeated measures analyses of variance contrasts.

Figure 2

Changes from baseline in markers of bone turnover in obese older adults during the 1-year interventions. Values are given as mean ± SE. CTX, C-terminal telopeptide of type 1 collagen (A); OC, Osteocalcin (B); PINP, Intact N-terminal propeptide of type 1 collagen (C). *P<0.05 for the comparison of the value from baseline, as calculated with the use of mixed-model repeated measures analyses of variance. ^†P<0.05 for the comparison of the value from control group, ^‡P<0.05 for the comparison of the value from diet group, ^§P<0.05 for the comparison of the value from exercise group, as all calculated with the use of mixed-model repeated measures analyses of variance contrasts.