Bone Mineral Density of the Lumbar Spine in College Rowers and Controls

Participants: Erica G. Hanson and Hawley C. Almstedt, Department of Natural Science at Loyola Marymount University

Abstract: Bone mineral density (BMD) begins to develop in the womb and continues to increase into adulthood, reaching a peak around age 30. Many factors contribute to the development of BMD including dietary intake, physical activity, and genetics.

Purpose: The main objective of our study was to look at the change in BMD at the spine over an 8-month training season in crew athletes compared with controls.

Methods: We measured BMD of 35 participants (14 male, 21 female), ages 18 to 25 years using dual-energy x-ray absorptiometry (DXA, Hologic Inc, Waltham, MA). Measurements were taken during preseason and after 8 months of training. Calcium intake (mg/d) and physical activity (MET-hours/wk) were quantified from questionnaires.

Results: Examining men and women separately, groups were not statistically different in age or calcium intake. Female crew athletes (n=10, mean years of rowing = 5.3), were more physically active (146 + 69 vs. 35 + 17 MET-hours/wk, p<.05), had a higher BMI (24.3 + 3.2 vs. 20.8 + 2.5, p<.05), and greater lean body mass (51.9 + 6.0 vs. 39.0 + 3.1, p<.01) than female controls (n=11). Male crew athletes (n=7, years of rowing=2.4), had a lower BMI (22.4 + 1.6 vs. 26.4 + 3.4, p<.05) than male controls. An analysis of covariance, controlling for lean mass, revealed that there were no significant differences in BMD, at the spine, after 8 months of rowing training for men or women. Although not statistically significant, male crew athletes showed a 1.3% increase in spinal BMD, while controls increased 0.9%.

Conclusions: Changes in BMD at the spine were not significantly different between rowing athletes and controls. Therefore, rowing did not seem to offer a significant advantage for bone health. In this convenience sample, overtraining by the athletes or restrictive eating practices in the light-weight rowers could be influencing results.

More Information: Erica Hanson is a 2008 graduate of the pre-physical and occupational therapy program with in the Department of Natural Science at LMU. She has been accepted and will enroll in the Doctoral of Physical Therapy program at University of Southern California beginning in the fall. Erica also presented her research at the CSE Wall of Fame reception and was accepted into Sigma Xi, the scientific research honor society. The research abstract above was presented at the 2007 Southwest American College of Sports Medicine Conference in San Diego. This research was supported by the internal Rains Research Assistant program.