Scheduled for Research Consortium Special Populations Poster Session, Friday, April 28, 2006, 10:45 AM - 12:15 PM, Convention Center: Exhibit Hall Poster Area I


Effects of Varying Exercise Programs on Bone Mineral Density and Muscular Strength for Untrained Older Women

Ro Di Brezzo, Inza Fort and Michelle Gray, University of Arkansas, Fayetteville, AR

Exercise, particularly weight bearing, is one key ingredient to retarding declines in bone mass. For some older women weight bearing exercise may be difficult and painful due to osteoarthritis. What is less known are the effects of other activities, specifically water exercise, on bone health and muscular strength. The purpose of this investigation was to examine bone mineral density (BMD), body composition, and muscular strength between three exercise programs. All participants were measured via dual energy x-ray absorptiometry and three repetition maximum. Thirty-six women ages 40-65 volunteered to participate in either, a traditional resistance (TR, n=16), a water resistance (WR, n=12), or a walking (W, n=9) group. Participants followed specific exercise prescriptions three days per week for a period of ten months. The TR group was instructed to perform three sets of 8-12 repetitions for all major muscle groups (lat pull-down, leg press, leg curl, lunges, triceps extension, biceps curls, and abdominal curls). The W group was directed to walk at 65%-75% of their age predicted maximum heart rate for at least 30 minutes and the WR group participated in a formal group exercise class focusing on increasing muscular strength. After 10 months, attrition had occurred across all groups, losing six participants in WR and TR and two in the W group. A dependent t-test was used to calculate pre-post changes within groups. There were statistically significant declines in BMD in both WR and W (p=0.030 and p=0.013, respectively) but no change in TR (p=0.124). Regarding strength, significant increases were made in latissimus dorsi (p<0.000), chest (p=0.001), hamstring (p<0.000), quadriceps (p=0.001), and triceps (p=0.017) in the TR group. Increases in lattissimus dorsi (p=0.034) and quadriceps (p=0.041) strength were seen in the WR group, while the W group only showed increases in the quadriceps (p=0.007) muscle group. No significant changes were observed in percent body fat (%BF) or lean mass for any group. Between the groups, changes following the exercise program were not statistically significant for BMD, %BF, or lean mass. For strength, significant differences between groups were seen in the lat pull-down (TR>W, p=0.009), chest press (TR>WR and W, p=0.006 and p=0.020, respectively), and leg curl (TR>WR and W, p=0.013 for both). Based on this, it appears that TR had an impact on BMD and overall muscular strength. Therefore, prescribing resistance exercise is particularly important in a time when women are prone to losing bone mass and strength.
Keyword(s): disease prevention, gender issues, older adult/aging issues

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