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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/cm2) and femoral neck (9.14 [-0.70, 18.98] mg/cm2) BMD was unchanged in RT+CR participants, and modestly decreased in AT+CR participants (total hip: -7.01 [-12.73, -1.29] mg/cm2; femoral neck: -5.36 [-14.92, 4.20] mg/cm2).


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.