This is a series of three experiments with brachial artery flow-mediated dilation (BAFMD) as the major outcome variable. The first study examined the temporal response of the brachial artery diameter following forearm occlusion in sixteen young (28±8 years) and fifteen older (85±8 years) men. Following release of the pressure cuff there is a significant reduction in brachial diameter compared to baseline, followed by a rapid increase to a PEAK. When comparing the magnitude of the decrease in diameter and the BAFMD between Young and Old, older subjects demonstrated a blunted response. A significant relation was noted between the magnitude of decrease and BAFMD (r=- 0.44, p= 0.04). Specific features of the biphasic pattern are blunted in older adults compared with younger subjects. The magnitude of the drop in diameter following forearm occlusion correlates with the magnitude of the BAFMD. The second study examined the relation between BAFMD and the total score from the Continuous Scale Physical Function Performance Test (PFP-10). Sixty-four men (84±11years) were studied. BAFMD was associated with the total PFP-10 score (r = 0.45, p = 0.0001) and age (r = -0.36, p = 0.003). When individuals were categorized based on their PFP-10 score, those in the highest functional class, exhibited the highest BAFMD, compared to those in the middle class, who had greater vasoreactivity than those in the lowest functional class. The final study examined the effects of four weeks of unilateral handgrip exercise training on BAFMD and the features of the vasoreactivity curve. Twelve men (81±5 years) were studied before, during and after four weeks of handgrip training of the non-dominant arm. Following training, a 40% increase in BAFMD was observed in the trained arm only. Significant improvements in BAFMD were observed after the second week of training (p=0.024). Also, BAFMD was significantly related to the estimated shear rate (r=0.341, p<0.001). A biphasic pattern was not observed in the present study. A significant improvement in BAFMD was observed following unilateral handgrip training. These improvements take place very rapidly and may be partly mediated through increases in shear stress resulting from changes in resistance vessel function.

Almost 42% of adults over 65 years of age live with at least one disability. Further, people of lower socioeconomic status and Blacks have greater risks for disability than Whites and individuals at higher socioeconomic status. The consequences of disability include loss of independence, decreased quality of life, increased chances of depression, consumption of health care services, and institutionalization. The purpose of this study was to utilize the disablement process framework to examine the contribution of physical function, dyspnea, and pain to disability in activities-of-daily-living (ADL) in culturally diverse older adults (i.e., diverse according to race, income, and education). Participants were 51 older adults (M age = 60.0 years, SD = 9.7) from an urban community center and an independent living housing facility for seniors with fixed incomes who completed the Functional Status Index (FSI), which provides ratings of need for assistance (FSIA) and pain (FSIP) with ADLs, the Continuous Scale Physical Functional Performance 10-item Test (CS-PFP10), and an analog dyspnea scale. Hierarchical multiple regression revealed that CS-PFP10 scores alone account for approximately 21% and 30% of the variance in FSIA scores of the participants from the community center and the housing facility, respectively. Adding FSIP and dyspnea ratings to the prediction model results in explaining an even higher portion of the variance in FSIA scores (36% in the community center and 53% in the housing facility). Based on this model, functional capacity improvement and pain and dyspnea prevention and management should be targeted when designing culturally appropriate strategies for delaying disability and maintaining independent life.

Chronic disease will never reach its clinical horizon to compromise health if it is attacked at its origin [1]. Knowledge that ones risk for cardiovascular events is related to the severity of endothelial dysfunction, and evidence that exercise training can improve endothelial function, has prompted speculation that measures of vascular function may serve as a barometer for cardiovascular health. This dissertation consists of three experiments intended to study vascular function and the manner in which it may influence or may be influenced by physical function. Project one examined the influence of high and low volume circuit weight training on forearm vascular function. Thirty-five individuals participated in a program consisting of 3 sessions/week for 5 weeks. Results indicated significant but similar strength gains in both groups (Hand Grip: Ä15.55%, Knee Extension: Ä21.00%, Bench Press: Ä35.31%; p<0.05). Reactive hyperemic responses, a measure of vascular function, only changed in those individuals with the lowest pre-training vascular measures, independent of group assignment. Project two examined the link between vascular and physical function in peripheral neuropathy patients. Reactive hyperemic responses were significantly related to the time up and go test (r=-0.31, p=0.02) and the 6-minute walk distance (r=0.37, p=0.007). These data suggest a link between measures of vascular and physical function in these patients, indicating that those with better vascular function have greater physical function. Project three examined the effects of an acute bout of exercise on nitric oxide, oxidative stress and anti-oxidants, and brachial vasoreactivity, before, at peak exercise, and in recovery, in trained individuals. The results indicated a significant increase in reactive oxygen species and peroxynitrite, and a decrease in the anti-oxidant glutathione peroxidase at peak exercise. Brachial vasoreactivity was significantly lower immediately after exercise, but returned to pre-exercise levels at 20 minutes into recovery. These findings suggest an acute bout of exercise contributes to a significant rise in oxidative stress, which can in part be buffered by anti-oxidants systems, but may cause temporary blunting of arterial reactivity. Collectively, these findings indicate the importance of examining vascular function, and its controllers, and may extend the current understanding of preserving and/or maintaining vascular health.

The goal of this research was to gain a better understanding of interplay between molecular biology, physiology, biochemistry, functionality with disease and interventions. The primary findings of the first study were that there was a significant inverse correlation between homocysteine and brachial artery flow mediated dilation (BAFMD) and baseline brachial artery diameter. Interestingly, there was a significant difference in BAFMD between methylene tetrahydrofolate reductase (MTHFR) genotype groups. Regression analysis indicated that the MTHFR genotype, homocysteine and age were significant predictors of BAFMD. The second study revealed that vascular reactivity as measured by BAFMD was modifiable. A meta-analysis of 22 intervention studies showed that exercise training produced significant changes in BAFMD. Fifteen of the twenty-two intervention groups had a statistically significant improvement in BAFMD. Only one study had a negative effect size (ES). Larger changes in BAFMD were seen in at risk/diseased subjects compared to healthy subjects. Shorter duration studies (< to 8 weeks) had a larger mean ES than did longer duration studies. In regards to training type the aerobic group had the largest ES. The meta-analysis revealed that physical training produces a large change in BAFMD, a biomarker of vascular health. Finally, study three revealed that middle-aged men and women instructed to consume a low-fat diet, reported, within 3 months, significant reductions in total fat, saturated fat, and cholesterol intake, which corresponded with a moderate, yet, significant change in LDL-cholesterol. However, the diet intervention appeared to have only a modest effect on lipid balance as indicated by small reductions in the total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios. Additionally, a clustering of lipid and vascular responses were seen indicating the array of responses to dietary interventions. Gene-diet interaction evaluation did reveal that genetic polymorphisms, such as the deletion at the apolipoprotein B signal peptide (24 amino acids) may be associated with varying responses to low-fat dietary interventions. Interestingly, the data suggest that despite self-reported reductions in total fat, saturated fat, and cholesterol intake, markers of vascular health were not significantly changed. However, individuals brachial artery reactivity increased by 3 months in both groups, which persisted throughout the trial.

According to the 2003 Youth Risk Behavior Surveillance Survey, 33% of youth in grades 9-12 participated in an insufficient amount of vigorous and moderate physical activity (PA), and 11% reported no vigorous and moderate PA. Although researchers have examined the psychological correlates of exercise behavior among youth, limited research investigating moderators of the theories of reasoned action (TRA; Ajzen & Fishbein, 1980) and planned behavior (TPB; Ajzen, 1985) in this population exists. Therefore, the main purpose of this study was to examine socioeconomic status (SES) as a moderator of the psychological correlates of exercise intention and behavior using the TRA/TPB in a youth population. The primary objectives of this study were to: (a) determine the psychological correlates of exercise intention, (b) determine the psychological correlates of exercise behavior, and (c) determine if SES moderates the relationships of the TRA/TPB constructs. It was hypothesized that attitude, subjective norm, and PBC would be significant correlates of exercise intention, and that attitude and PBC would be the strongest predictors. It was also hypothesized that intention and PBC would be significant correlates of exercise behavior, and that intention would be the strongest predictor of behavior followed by PBC. Finally, it was hypothesized that no significant differences would be observed on the TRA/TPB constructs based on SES. The final sample included 309 8th and 9th grade male and female students (M age = 14.36 years, M BMI = 22.46). Most of the participants were 9th grade students (54.0%), female (63.4%), Caucasian (72.2%), and part of families living above the median income level in Louisiana (49.8%). Participants completed measures of past exercise behavior, attitude, subjective norm, intention, and perceived behavioral control (PBC) for exercise behavior during their physical education or health classes. Consistent with previous TPB research, hierarchical regression analyses showed that attitude, subjective norm, and PBC explained 49.2% of the observed variation in exercise intention, and that PBC was the strongest predictor; however, subjective norm was a more important predictor of exercise intention than attitude. In addition, intention and PBC explained 32.7% of the variance in exercise behavior and intention was the strongest determinant followed by PBC. Finally, there was no evidence of SES moderation of the TRA/TPB constructs. More specifically, no group differences were identified for those students above the median income compared to those at or below the median income on the TRA/TPB constructs and exercise behavior. Furthermore, when the interaction terms were added to the regression models they did not add a significant amount of explained variance and none of the interaction terms were significant predictors of exercise intention and behavior. These findings support the hypotheses of the TRA/TPB in that exercise behavior is largely influenced by intention and PBC, and the findings indicate that SES is not a moderating factor of the TRA/TPB. Therefore, health care professionals, researchers, and practitioners may use this information to develop and test behavior change strategies that target intention and PBC for exercise among adolescents from varied SES backgrounds to determine if exercise behavior can be changed.

Traditionally, contextual interference (CI) has been investigated by the use of extreme low and high levels of CI (blocked and random practice schedules); with results generally suggesting that higher rather than lower amounts of CI facilitated motor skill learning (Magill & Hall, 1990). To better understand the CI effect, two experiments were conducted investigating an alternative form of practice schedule. Practice using this alternative schedule provided novices experiences with systematic increases in CI, which were compared to traditional blocked and random scheduling. Experiment 1 tested the hypothesis that practicing variations of the same tasks with systematic increases in CI would lead to superior performance when practicing the same tasks in a blocked or random schedule. Participants (N=60) practiced a golf putting task at three distances for a total of 81 trials following either a blocked, random, or increasing practice schedule. The increasing schedule had participants practice the first 27 trials with blocked scheduling, followed by 27 serial trials, practice then concluded with 27 trials of random scheduling. Results showed that participants who followed the increasing schedule generally performed better on a retention and transfer test when compared to participants practicing the same tasks following blocked and random schedules. The purpose of Experiment 2 was to test if the learning benefits of an increasing schedule were limited to variations of the same task or if the benefits were generalizable to tasks with different invariant features, thus being controlled by different generalized motor programs (GMP). In this experiment novice participants (N=96) practiced three different basketball related passes (chest, overhead, single arm). Using methods similar to Experiment 1, participants practiced the three passes in a blocked, random, or increasing schedule for 81 trials. Results showed that participants who practiced with gradual increases in CI generally performed better on a retention and transfer test compared to participants who practiced with traditional blocked or random scheduling. The results of these two experiments indicate that a practice schedule offering systematic increases in CI facilitates skill learning and these learning benefits are generalizable to tasks controlled by the same or different GMPs.

The 108th Congress (2005) has reported that 20 million U.S. citizens suffer from Peripheral Neuropathy (PN). Characterized by sensory nerve deterioration, PN reduces somatosensation (Padua et al., 2005) and increases the risk of fall-related injury (Richardson et al., 1992). The purpose of this dissertation was to provide insight into 1) the effects of acute loss of foot sole sensation on locomotor system health, 2) the effects of PN on locomotor system health, and 3) the underlying impairments associated with reduced physical function within the older adult and PN populations. Locomotor system health was assessed by the magnitude of stride-to-stride variability and local instability contained in the kinematics of treadmill walking. In healthy young adults, ice-induced reduction of foot sole sensation did not alter the magnitude of stride-to-stride variability during treadmill walking. It did, however, increase lower-extremity joint local instability, or the sensitivity to small scale perturbations. Compared to controls, individuals with PN walked with similar local instability yet increased variability, at relatively slow speeds. When walking at relatively fast speeds, individuals with PN exhibited exaggerated increases in local instability. In healthy older adults, locomotion-based physical function (LBPF), as defined by 6-minute walk and Timed Up-and-Go performance, was correlated to leg strength and measures of locomotor system health. However, only measures of locomotor system health provided independent predictive information of LBPF. The PN group exhibited reduced LBPF. As opposed to healthy old adults, correlates of LBPF were not leg strength but instead standing balance variables. Multiple variables of leg strength, standing balance, and locomotor system health provided independently predictive information regarding each test of LBPF. The opposing effects of ice-induced reduction in foot sole sensation and PN on locomotor system health suggest that the chronic nature of PN allows for the implementation of partially effective compensatory strategies. Yet, the inability to adapt to relatively fast speeds suggests that falls likely occur during challenging situations. The fundamentally different correlates and predictors of LBPF between older adults and those with PN highlight the uniqueness of the movement disorder associated with PN.

Hormones are typically considered to be chemical messengers, which are designed to be released from specific cells where they are carried to their target tissues for binding to receptors. It is this binding of a hormone molecule to its specific receptor which allows for an action to occur (Hadley and Levine 2006). Testosterone is the predominant androgen in the majority of mammalian species and is largely responsible for regulation of reproduction and maintenance of sexual function. In addition, in adult mammals, T has multiple other roles including the growth of muscle and bone, hematopoesis, blood coagulation, development and regulation of plasma lipids, protein and carbohydrate metabolism, and cognitive function (Bhasin, 2005). Cortisol has typically been thought of as a suppressor of the immune system and an anti-inflammatory agent as it is an inducer of cellular apoptosis. In research where corticosteroids were given intravenously to humans, responses of apoptosis of T and B cells were noted (Cohen and Duke 1984). Testosterone and C as well as other hormones have received significant attention in recent years by several researchers who have proposed a link between these hormones and performance, adaptive capability, and overtraining syndrome (Kraemer & Ratamass, 2005). The use of T to C ratio (T/C) has gained some popularity in recent years as a method to monitor anabolic/catabolic state in athletes, and to predict athletic performance and/or overtraining. There is a growing body of evidence that T/C may be useful in monitoring training stress and physiological phenomenon, however, the relationship between these variables and any actual physical performance has not been solidly established at this time.

A high fat diet causes a reduction in the expression of the genes of the electron transport chain, mitochondrial carrier proteins, and PGC-1α and PGC-1ß mRNA. Mitochondrial dysfunction has been linked to numerous chronic diseases. The antioxidant quercetin has been shown to protect against damage caused by exogenous and endogenous free radicals. The purpose of this study was to determine if quercetin would protect the genes of mitochondrial biogenesis (PGC-1α and PGC-1ß) and OXPHOS regulation (NDUFB5 and SDHB) from the downregulation caused by consumption of a high fat diet. The quadriceps muscle was removed from 21 male, C57BL/6J mice that had been fed a low fat (10% kcal fat), a high fat (45% kcal fat), or a high fat plus quercetin (45% kcal fat + 1.2% quercetin) diet for 3 weeks. RNA was isolated from the samples and quantitative RT-PCR was used to compare gene expression. As expected, there was a significant difference between gene expression in the low fat group compared to the high fat and high fat plus quercetin groups for all measured genes (pgc-1α: F = 5.76, df = 2, P = 0.011; pgc-1ß: F = 5.28, df = 2, P = 0.016; NDUFB5: F = 5.66, df = 2, P = 0.012; SDHB: F = 5.04, df = 2, P = 0.018). We found no significant difference between gene expression of the high fat group compared to the high fat plus quercetin group (pgc-1α: t = -0.71, df = 12, P = 0.49; pgc-1ß: t = 0.16, df = 12, P = 0.87; NDUFB5: t = 0.27, df = 12, P = 0.79; SDHB; t = -0.20, df = 12, P = 0.84). These results indicate that this dose of quercetin is not effective in protecting the expression of genes associated with mitochondrial health from the deleterious effects cause by consumption of a high fat diet.

For both healthy individuals and individuals at high risk of falling, certain environments, such as a dual-task situation, require more resources than others to prevent a loss of balance. Stepping assessment tasks can be used to predict falls, and it has been suggested that impaired voluntary stepping may be a contributing factor to falls (Lord & Fitzpatrick, 2001). In this research, a stepping task was used not as an assessment, but as a therapeutic intervention. The purpose of this research was to determine how training with a task that provides a procedural learning environment can affect balance and functional outcomes. The divided-attention timed stepping accuracy task required participants to step to and from 16 targets in a random order as quickly and accurately as possible. The physical stepping task was performed simultaneously with a cognitive information-processing task that involved attending to verbal cues to determine the next target while visually monitoring the environment to ensure accuracy requirements were met. Training sessions lasted approximately 30 min and were performed three times per week for 6 weeks. In experiment 1, a single-case experimental design, an individual with a 4 year history of an incomplete cervical spinal cord injury demonstrated improvements in balance, endurance, and functional tasks. In experiment 2, a pretest, posttest control group design, healthy older adults aged 65 years and above had significant improvements in the areas of balance, divided-attention performance, functional task performance, endurance and strength. In experiment 1, it was hypothesized that a procedural learning environment had been established and this was substantiated in experiment 2. The results from experiment 2 indicate that strength and endurance may have accounted for some of the improvements seen, but there is sufficient evidence that much of the improvement could be accounted for by procedural learning. In experiment 2, training resulted in simultaneous improvements in both the physical and cognitive aspects of the task. This research has immediate clinical applications and future studies may substantiate other potential clinical applications.