Purpose/Hypothesis: The question that is asked continually by therapists and patients alike is “Can exercising in the water preserve or build the bone mass density (BMD) in atrisk aging population?” While there is a moderate evidence for the beneficial effects of the land-based weight-bearing exercise programs on postmenopausal bone loss, the support for the aquatic exercises to combat bone loss in postmenopausal women remains controversial. There is, therefore, a critical need for well-designed trials that are rooted in the scientific evidence and based on exercises that can provide mechanical loads exceeding the ones applied to the bone during everyday life. The purpose of this study was to determine whether the high impact jumping exercises performed in an aquatic environment maintains or improves the BMD in postmenopausal women.
Number of Subjects: 28 participants met inclusion criteria: 1) healthy, ambulatory, and community dwelling postmenopausal Caucasian women, and 2) have no impairment in mental or physical function that may affect ability to exercise under water or follow instructions.
Materials and Methods: This pilot study compared the left femoral neck and lumber spine BMD in 28 postmenopausal women following a 12-week pool-based high impact jumping aquatic exercise program (AEP) compared with no exercise program (NEP), with postmenopausal women serving as their own control (crossover study design). BMD was measured by a bone densitometer (Horizon A, Hologic Inc., Waltham, Massachusetts, USA) using dual-energy xray absorptiometry. In addition, we explored the effect of 12-week AEP on the BMD in postmenopausal women at 3-month follow-up.
Results: 17 participants (56.0±6.23, 71.30±3.70 kg, and 1.63±.06 meters) completed the study. Data from 11 participants was not analyzed because they did not complete the study. One-way repeated measures ANOVA was conducted to analyze the differences in BMD, which failed to elicit statistically significant changes in both left femoral neck and lumber spine BMD over time (p<.05). A non-statistically significant change in % BMD was observed in the femoral neck (0.40%) and lumbar spine (-0.14%) in participants post-intervention.
Conclusions: Although the study failed to demonstrate significant differences in the regional BMD at both femoral neck and lumber spine, an increase in femoral neck area was expected because of the increased resistance (water-drag) that participants had to counter while doing jumping exercises at higher speed. The lack of BMD increase in the lumber spine area could be partially attributed to decreased bone-loading due to the buoyancy of water.
Clinical Relevance: In this pilot study, 12-week pool-based high impact jumping aquatic exercise program failed to increase regional BMD; however, no adverse effects of pool exercise training on bone mass were observed, such as bone demineralization. Further studies with a larger sample size and increased intervention duration/volume using more sessions per week or higher strains may show improvement in regional BMD.