Kinesiology
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Item The influence of ECE-1 gene polymorphism and exercise training on plasma and urinary endothelin-1 levels in pre- and stage 1 hypertensives(2007-08-09) Attipoe, Selasi; Hagberg, James; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Endothelin-1 (ET-1) is a peptide that mediates blood pressure. ECE-1b-C-338A is a polymorphism in the ECE-1 gene that alters ET-1 synthesis. Thus, the goal of this study was to investigate the influence of the ECE-1b-C-338A polymorphism on plasma and urinary ET-1 levels, as well as on aerobic exercise training (AEX)-induced changes in these variables. Outcome variables were assessed before and after 24 weeks of AEX in hypertensive adults. Separate ANCOVAs were used to compare differences in outcome variables. Only AA homozygote men had higher plasma ET-1 levels. After AEX, there were no significant changes in the main outcome variables. Neither were these changes significantly different between genotype groups. Results suggest that this polymorphism is associated with plasma ET-1 levels in men but not with urinary ET-1 levels. Additionally, this polymorphism does not affect AEX-induced changes in plasma and urinary ET-1 levels.Item Relationship between physical activity and telomere maintenance in peripheral blood mononucleocytes(2007-07-24) Ludlow, Andrew Todd; Roth, Stephen M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The purpose of this study was to examine the relationship between exercise energy expenditure (EEE) and telomere length, telomerase activity, and hTERT genotype. Sixty-nine male (n = 34) and female (n = 35) participants 50-70 yr. were assessed for weekly EEE level using the Yale Physical Activity Survey. Subjects were grouped according to EEE. Telomere length and telomerase activity were measured in peripheral blood mononuclear cells (PBMCs). Relative telomere length was significantly higher in the Middle EEE group compared to both the low and high EEE groups (p<0.05). Telomerase activity was not different among the three EEE groups. The TT hTERT genotype had significantly greater telomerase enzyme activity than both the CT and CC genotypes (P = 0.013). In conclusion, moderate exercise energy expenditure levels may provide a protective effect on PBMC telomere length compared to both low and high EEE levels. hTERT genotype was associated with telomerase activity.Item The Effects of Strength Training on Regional Body Composition in Older Adults: Sex and Race Comparisons(2007-05-22) Walts, Cory; Hurley, Ben F; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Purpose: To examine the influence of sex and race on the effects of strength training (ST) on thigh muscle volume (MV), mid-thigh subcutaneous fat (SCF) and intermuscular fat (IMF). Methods: One hundred and eighty-one previously inactive healthy Caucasian (N=117), African-American (N=54), and other (N=10) men (N=82) and women (N=99), aged 50-85 yrs, underwent ~10 weeks of unilateral knee extension ST. Results: Training-induced increases in absolute MV were significantly greater (P < 0.01) in men than in women. There were significant increases in MV within each race (P < 0.001); but no significant differences between races. There were no significant changes in SCF and IMF whether sex and racial groups were separated or combined. In addition, there was no sex by race interaction for changes in MV, SCF, or IMF with ST. Conclusion: Ten weeks of unilateral strength training does not alter subcutaneous or intermuscular fat regardless of sex or racial differences. Although men exhibit a greater muscle hypertrophic response to strength training compared to women, the difference is small. Race does not influence this response.Item The Dynamics of Multi-sensory Re-weighting in Healthy and Fall-prone Older Adults(2006-08-04) Allison, Leslie K.; Jeka, John J.; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Multi-sensory re-weighting (MSR) is an adaptive process that prioritizes the visual, vestibular and somatosensory inputs that provide the most reliable information when environmental conditions change. This process is thought to degrade with increasing age, and to be particularly deficient in fall-prone versus healthy older adults. This dissertation presents three studies designed to investigate age- and fall-related changes in MSR. The first study examined the assumption of impaired MSR in healthy and fall-prone older adults using a two-frequency touch/vision experimental design with stimuli at varying amplitudes. Both healthy and fall-prone older adults demonstrated the same pattern of adaptive gain changes as healthy young adults. No group differences in the overall levels of vision and touch gain were found. These results suggest that, for small amplitude vision and touch stimuli, the central sensory re-weighting adaptation process remains intact in healthy and fall-prone older adults. In the second study the effects of a sensory-challenge balance exercise program on laboratory measures of MSR and clinical measures of balance were investigated. Following the intervention the normal adaptive pattern of gain change was unaltered, while declines in overall vision and touch gains that reflect down-weighting of the sensory stimuli were seen. Improvements in four clinical balance measures were observed. These findings indicate that MSR processes in fall-prone older adults are modifiable, that sensory challenge balance exercises may facilitate the ability to down-weight unstable sensory inputs, and that these effects may generalize to other components of balance. A third study explored the dynamics of sensory re-weighting in healthy and fall-prone older adults. Absolute levels of gain, and the rate of adaptive gain change, were examined before and after large changes in visual motion stimulus amplitude. Compared to young adults, gains in both older adult groups were higher when the stimulus amplitude was high, and gains in the fall-prone elderly were higher than both other groups when the stimulus amplitude was low. Both older groups demonstrated slowed sensory re-weighting over prolonged time periods when the stimulus amplitude was high. These results reflect age- and fall-related changes in the extent and rate of down-weighting unstable visual inputs.