Rowing Exercise Is Associated With Reduced Resistance To Bending At The Hip In Older Women

Abstract

Previously we found rowing exercise was associated with increased spine bone mineral density (BMD) and increased back strength in older women. However, little is known about the effects of rowing exercise on hip BMD and structure in older women. PURPOSE: Our aim was to examine bone mass and bone structure of the hip in older competitive female rowers (N = 21, age 56.4+5.9 y) and age-matched controls (N = 21, age 57.2 + 4.8 y). METHODS: Estrogen-deplete competitive rowers (avg. years rowing = 6.4+7.7 y) were recruited from nine rowing clubs in the local area and compared to normally active controls who were not participating in rowing activity. Women were excluded if they were taking any bone altering medication including bisphosphonates and hormone replacement therapy. Strength of the proximal femur (estimated by cross sectional area (CSA) and cross sectional moment of inertia (CSMI) at the narrow neck (NN) and intertrochanter (IT) was assessed by Hip Structure Analysis (HSA) software derived from DXA scans. Total hip BMD was measured by DXA. Subjects completed questionnaires to assess diet, physical activity, medical history and rowing history. Group differences in total hip BMD, CSA and CSMI at the NN and IT were determined using analysis of variance, controlling for height (cm), lean mass (kg) and non-rowing physical activity (MET*hrs/week). RESULTS: There were no differences in total hip BMD, NN CSA, or NN CSMI between groups. Trends were observed at the IT region. Rowers had lower adjusted CSMI (9.9+2.2 cm4 vs. 10.8+2.6, p=0.055) and lower IT CSA (4.1+0.6 cm2 vs. 4.4+0.7) compared to controls. Lower values at these sites indicate inferior resistance to bending in rowers compared to controls. There were no differences in total calcium intake, age, menopausal status, weight, non-rowing physical activity or lean mass between groups. CONCLUSIONS: These data emphasize the site specific nature of bone loading. The benefits of rowing exercise previously observed at the spine are not evident at the hip. It is possible that the seated nature of rowing results in mechanical unloading of the hip leading to reduced hip bone strength. Rowers may benefit from additional impact or resistance exercises targeting the hip to maximize skeletal health. Supported by the Northwest Health Foundation, the Bone Research Laboratory, and Concept 2 Inc.