Honors Students' Abstracts
College-Age Dancers Have Stronger Bones than Runners and Controls, Despite Low Energy Availability
Osteoporosis is a rising issue amongst postmenopausal women and one of the best ways to combat this disease is to develop a healthy bone mineral density (BMD) as a young adult. It has been shown that BMD and menstrual function are influenced by energy availability (EA). EA is kilocalorie (kcal) consumption minus kcals expended through activity. The inter-relationship amongst bone health, menstrual status, and diet is commonly known as the Female Athlete Triad. The purpose of this research study is to evaluate the influence of EA on BMD in runners, dancers, and controls. We measured BMD at several different sites in 39 subjects (13 runners, 11 dancers, and 15 controls) using dual-energy x-ray absorptiometry (DXA, Hologic Explorer, Waltham, MA). We also measured daily dietary intake using the Block 2005 Food Frequency Questionnaire (Nutrition Quest, Berkeley, CA) and energy expenditure over an average of four days using an accelerometer (Philips Respironics Actical, Bend, OR). The average age of our participants was 19.8±1.1 years. Runners were recruited from a NCAA Division I cross-country team, dancers were actively pursuing a BA in dance, while the controls were normally-active college students. When examining the EA between each group there were no significant differences (Dancers= 29.9±17.0 kcals/kg lean mass, Runners= 24.2±8.0 kcals/kg lean mass, Controls= 31.9±13.7 kcals/kg lean mass). However, an ANCOVA (with BMI as a covariate) revealed that dancers have significantly higher BMD at the anterior-posterior spine (mean=1.06±0.10 g/cm2) than runners (mean=0.94±0.07 g/cm2, p<0.05) and controls (mean=0.97±0.09 g/cm2, p<0.05). Dancers (mean=0.97±0.13 g/cm2) also have significantly greater femoral neck BMD than controls (mean=0.85±0.10 g/cm2, p<0.01) however the BMD of dancers at the hip was similar to the runners (mean=0.88±.06 g/cm2). On the other hand, groups had similar BMD at the whole body. According to previous research, EA for all groups was below recommended. Our research shows that despite the low EA, dancers have healthy BMD. This implies that the loading nature of dancing has a greater positive influence on bone health than EA and running.