Change in Bone Mineral Density During Weight Loss with Resistance Versus Aerobic Exercise Training in Older Adults

Background: To examine the effect of exercise modality during weight loss on hip and spine bone mineral density (BMD) in overweight and obese, older adults. Methods: This analysis compared data from two 5-month, randomized controlled trials of caloric restriction (CR; inducing 5-10% weight loss) with either resistance training (RT) or aerobic training (AT) in overweight and obese, older adults. Participants in the RT + CR study underwent 3 days/week of 8 upper/lower body exercises (3 sets, 10 repetitions at 70% 1 RM) and participants in the AT+CR study underwent 4 days/week of treadmill walking (30 min at 65-70% heart rate reserve). BMD at the total hip, femoral neck, and lumbar spine was assessed via dual-energy X-ray absorptiometry at baseline and 5 months. Results: A total of 123 adults (69.4 +/- 3.5 years, 67% female, 81% Caucasian) participated in the RT+ CR (n = 60) and AT+ CR (n = 63) interventions. Average weight loss was 5.7% (95% CI: 4.6-6.7%) and 8.2% (95% CI: 7.2-9.3%) in RT+ CR and AT+ CR groups, respectively. After adjustment for age, gender, race, baseline BMI and BMD, and weight change, differential treatment effects were observed for total hip and femoral neck (both p < .05), but not lumbar spine. Total hip (1.83 [-3.90, 7.55] mg/cm(2)) and femoral neck (9.14 [-0.70, 18.98] mg/cm(2)) BMD was unchanged in RT+ CR participants, and modestly decreased in AT+CR participants (total hip: -7.01 [-12.73, -1.29] mg/cm(2); femoral neck: -5.36 [-14.92, 4.20] mg/cm(2)). Conclusions: Results suggest performing resistance, rather than aerobic, training during CR may attenuate loss of hip and femoral neck BMD in overweight and obese older adults. Findings warrant replication from a long-term, adequately powered, RCT.