Masters Theses

Date of Award

8-2004

Degree Type

Thesis

Degree Name

Master of Science

Major

Exercise Science

Major Professor

Dixie Lee Thompson

Committee Members

Edward Howley, David R. Bassett

Abstract

The primary purpose of this study was to examine the relationship between ambulatory physical activity (steps per day) and bone variables in healthy, Caucasian postmenopausal women. Additionally, we examined the relationship of body mass (BM), lean mass (LM), and fat mass (FM) with bone variables in this group of women, Average steps taken per day were compared to bone mineral density (BMD) in 93 postmenopausal women (60.8 ±5.8 yrs). Ambulatory physical activity (steps per day) was measured for 14 consecutive days using a Yamax Digi-Walker SW-200. Additionally, current physical activity (PA) level was estimated using a Paffenbarger Physical Activity Index (PAI) and Seven Day-Recall Questionnaire (PAR). Total daily caloric intake was estimated by 3-day dietary record. When we examined all 93 subjects together ambulatory PA was negatively correlated with age, body mass index (BMI), and BM. There was a significant linear relationship between ambulatory PA and PAI (P < 0.001), but no significant relationship between ambulatory PA and any of the total or regional BMD or bone mineral content (BMC) values (P > 0.05). Body mass was associated with total BMD (TBMD), BMDLEG, total BMC, and BMCLEG, while FM was associated with only total BMD, BMDLEG , and BMCLEG. Lean mass was strongly associated with total and regional BMD and BMC. Age was negatively related to TBMD, BMDLEG, and LM. Because of the strong relationship ob BM to bone variables, we expressed bone variables relative to BM. A modest, yet highly significant, relationship was then seen between daily steps and BMD and BMC. The participants were broken down based on steps taken per day into 3 different activity groups: least active (<5,500), moderately active (5,500-7,500), and most active (>7,500). There was no significant difference in uncorrected total or regional BMD or BMC for the activity groups. When subjects were grouped according to reported hormone replacement therapy (HRT) use (HRT=yes HRT, NHRT=no HRT), we found that ambulatory OA was negatively correlated with age, BMI, and BM in NHRT, but in YHRT group this negative correlation was only seen between daily steps and age. We found that there was no significant relationship between daily steps and uncorrected total or regional BMD and BMC measured for either HRT group. In conclusion ambulatory PA has no significant effect on uncorrected BMD or BMC in postmenopausal women. When bone variables are expressed relative to BM, ambulatory PA is significantly related to bone variables.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS