<p>Body weight supported devices available to enhance locomotor recovery following an incomplete spinal cord injury (SCI) include treadmills with (Lokomat^TM) and without (Manual Treadmill) robotic assistance, and the overground ZeroG^TM system. Cardiovascular and muscular demands of these devices were compared during steady-state locomotion at the <em>same</em> level of body weight support (BWS) in 7 individuals with incomplete SCI (42.6±4.29 years) and matched able-bodied controls (CON). Questionnaires evaluated consumer preference based on walking experience. Oxygen uptake (VO₂), heart rate (HR) and ratings of perceived exertion (RPE) were expressed as percentage of peak values obtained using arm ergometry. Additionally, VO₂ was expressed relative to resting metabolic equivalents (METS). Filtered electromyography (EMG) signals from tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF) and medial gastrocnemius (MG) were normalized to ZeroG^TMstepping. Lokomat^TM sessions were the least demanding in terms of oxygen uptake compared to the Manual Treadmill and ZeroG^TM, and considered the least appropriate device for the SCI group’s current level of function. For SCI, the a) ZeroG^TM required 3.0 METS, 54.7% of VO₂peak, 84.7% of peak HR, b) Manual Treadmill required 2.8 METS, 52.9% of VO₂peak, 80.8% of peak HR and c) Lokomat^TM required 1.7 METS, 30.1% of VO₂peak, 67.3% of peak HR. Central RPEs were 3.8, 3.7, 0.5 and peripheral RPEs were 5.1, 4.1, 0.7 for the ZeroG^TM, Manual Treadmill and Lokomat^TM respectively. For CON, walking required minimal effort (at most 31.5% of VO₂ peak), with ZeroG^TM sessions requiring greater muscle activation. For SCI, muscle activation was higher in treadmill conditions compared to the ZeroG^TM due to increases in TA and BF activity. The Manual Treadmill and ZeroG^TM should be considered progressions following Lokomat^TM training where hip extension can be encouraged using the treadmill and additional components of gait (e.g. balance, torso stability) can be focused on using the ZeroG^TM.</p> / Master of Science (MS)

This dissertation investigated 1) the energy expenditure of stepping in place during TV commercials (commercial stepping), 2) determined the best objective tool to measure commercial stepping, 3) and assessed the efficacy of commercial stepping to increase the activity levels of sedentary, overweight adults. First, twenty-three adults (normal to obese) had their energy expenditure measured while at rest, sitting, standing, stepping in place and walking at 3.0 mph on the treadmill, followed by one hour each of sedentary TV viewing and commercial stepping in the laboratory. Stepping in place, walking at 3.0 mph, and commercial stepping, had a higher caloric requirement than either rest, or sedentary TV viewing. One hour of commercial stepping resulted in an average of 2111 actual steps. The waist mounted Digiwalker and New Lifestyles pedometers counted 72% and 80% of steps, while the ankle mounted Omron and Stepwatch counted 100% and 98% of actual steps respectively. Having established commercial stepping as a moderate intensity-measurable activity, eleven adults, participated in a 3-week pilot study to investigate the effects of commercial stepping at home (one week baseline, followed by two weeks commercial stepping across ≥90 min/day of TV watching). Compared to baseline, adults took more steps when watching TV, and watched 34% less TV during the 2nd two weeks. In the free-living environment, the StepWatch counted significantly more steps than the Omron pedometers (ankle and waist). Thirdly, this study compares two physical activity prescriptions: 1) commercial stepping across ≥90 min/day of TV watching; and 2) walking ≥30 min/day in 58 sedentary overweight adults. Outcomes were daily steps, adherence, dietary intake, TV watching and weight after 12 wks in a behavioral intervention. Both groups adhered equally to their prescriptions, and daily steps significantly (P<0.05) increased (~3000 steps/day) from 0 to 12-wks, with no difference between groups. TV viewing was significantly (P<0.05) reduced in both groups. Despite a reduction (P<0.05) in self-reported dietary intake, there were no changes in weight in either group. Instructing people to step in place during 90 minutes of TV watching results in a change in daily steps roughly equivalent to encouraging people to walk 30 min/day.

Purpose: To determine the step count accuracy of three pedometers and one accelerometer in pregnant women during treadmill walking. Methods: Subjects were 30 women in the second or third trimester (20-36 weeks) who were screened for pregnancy-related risk factors. Each subject was fitted with a belt containing three physical activity monitors: Yamax Digiwalker SW-200 (DW), New Lifestyles NL 2000 (NL), and GT3X Actigraph accelerometer (ACT). The Omron HJ-720 (HJ) was placed in the pants pocket. Subjects walked at 54, 67, 80, and 94 m•min-1 for two minutes each. Actual steps were determined by an investigator using a hand-tally counter. Percentage of actual steps was calculated for each device at each speed and compared. Results: There was a significant interaction between speed and device (F9,20=7.574,P<0.001). At all speeds, the NL and HJ were most accurate. At 54 m•min-1, the DW was significantly less accurate (P<0.001) than all other devices and the ACT was significantly less accurate (P<0.001) than the NL and HJ. At 67 m•min-1, the ACT and DW were significantly less accurate (P<0.001) than the NL and HJ. At 80 m•min-1, the DW was significantly less accurate (P=0.024) than the NL and HJ. At 94 m•min-1, the ACT was significantly less accurate (P=0.001) than the NL and HJ. No significant differences were found at any speed for the NL (P=0.996) and HJ (P=0.298). Trimester did not significantly affect device accuracy. Conclusion: In pregnant women, the ACT and DW are less accurate than the NL and HJ. The HJ appeared to be the most accurate. These results can be useful in developing further research studies and physical activity programs that focus on walking during pregnancy.

Greenways (GW) can be sited to increase the potential for individuals to access the GW through active transit (AT) and provide opportunities for individuals to meet PA guidelines. PURPOSE: To determine if GWs, with varying AT access potential, relate to user characteristics and their GW-related PA. METHODS: A trail intercept survey measuring access mode, GW-specific PA, and demographics of GW users was administered to 611 adults on 2 GWs with high and low AT potential (GWhigh vs. GWlow). RESULTS: Users of GWhigh(N=216) compared to GWlow (N=400) were more likely to be younger, male, never married, employed, and affluent; accessing the GW via AT modes and accumulating greater volumes of GW-only and total GW-related PA (GW-only & AT PA). No difference in the proportion GW users meeting the 2008 PA Guidelines from GW-only PA was found however, 10.5% more users of GWhigh met the guidelines from total GW-related PA compared to GWlow (p=0.039). Users who accessed GWhigh by AT rather than cars were more likely to be not married (OR=2.6, 95% CI: 1.1 – 6.3), under 35 years old (OR=6.0, 95% CI: 1.9 – 19.26), live a mile from the GW (OR=5.39, 95% CI: 2.3 – 14.3). CONCLUSION: The profile of GW user and the way PA is acquired is related to the AT accessibility of GWs. Although PA levels of GWhigh users were significantly higher, GWlow usage was greater. Therefore, GW planners and designers should incorporate universal design concepts and conduct needs based assessments to properly site and design GWs to serve the greatest portion of the population.

Purpose: To determine the step count accuracy of three pedometers and one accelerometer in pregnant women during treadmill walking. Methods: Subjects were 30 women in the second or third trimester (20-36 weeks) who were screened for pregnancy-related risk factors. Each subject was fitted with a belt containing three physical activity monitors: Yamax Digiwalker SW-200 (DW), New Lifestyles NL 2000 (NL), and GT3X Actigraph accelerometer (ACT). The Omron HJ-720 (HJ) was placed in the pants pocket. Subjects walked at 54, 67, 80, and 94 m•min-1 for two minutes each. Actual steps were determined by an investigator using a hand-tally counter. Percentage of actual steps was calculated for each device at each speed and compared. Results: There was a significant interaction between speed and device (F9,20=7.574,P<0.001). At all speeds, the NL and HJ were most accurate. At 54 m•min-1, the DW was significantly less accurate (P<0.001) than all other devices and the ACT was significantly less accurate (P<0.001) than the NL and HJ. At 67 m•min-1, the ACT and DW were significantly less accurate (P<0.001) than the NL and HJ. At 80 m•min-1, the DW was significantly less accurate (P=0.024) than the NL and HJ. At 94 m•min-1, the ACT was significantly less accurate (P=0.001) than the NL and HJ. No significant differences were found at any speed for the NL (P=0.996) and HJ (P=0.298). Trimester did not significantly affect device accuracy. Conclusion: In pregnant women, the ACT and DW are less accurate than the NL and HJ. The HJ appeared to be the most accurate. These results can be useful in developing further research studies and physical activity programs that focus on walking during pregnancy.

The purpose of this study was to explore the differences in the aerobic response to wheeling between wheelchair dependent individuals and able-bodied individuals of similar genders and ages. Five wheelchair dependent men (WC) and five able-bodied men (AB) performed a 13 minute wheeling test (5 min. at rest, 8 min. wheeling) at 4.0 km∙hr-1. Heart rate (HR) and VO2 were recorded using a Vmax ST system during the constant speed test. There was no significant difference in HR or VO2 between the two groups during rest. Both HR and VO2 were higher for WC during exercise. The mean METS during exercise for WC and AB were 3.589 ± 0.516 and 2.726 ± 0.164, respectively. The results indicate that at a given workload a spinal cord injured wheelchair user will have a greater aerobic response than an able-bodied person in a wheelchair completing the same task.

Older adults face many age-related changes affecting functional ability. Function is defined as the interaction between a person and their real-world environment. Currently, no objective measures of function exist assessing the environmental component. A newly-developed measure of functional-living, the Movement and Activity in Physical Space (MAPS) score, combines accelerometer and geospatial data providing quantitative measurement of real-world function. Because MAPS is a new measure of functional-living, the purpose of the current study was to provide further construct validity for MAPS as a functional-living measure in older adults and to determine what combination of 3 days, using weekend and week days, are needed to obtain reliable MAPS scores in older adults. While there are many factors known to impact function, cognitive function has a well-known relationship with physical activity. MAPS assesses physical activity. Therefore, a relationship between cognitive function and functional-living was expected. Physical activity and physical function were also expected to be related to functional-living. Thirty community-dwelling older adults aged 72.6 (± 7.0) completed the study. Five measures of cognitive function were used, each assessing a different cognitive domain (i.e., executive function, working memory, processing speed, reaction time, and spatial visualization). A physical function test and a measure of physical activity were also administered. Pearson r correlations were conducted among all measures to assess the correlations between MAPS scores and the measures of cognitive function, physical activity questionnaire, and physical function test. If a correlation was found to be significant between MAPSI and MAPSV scores with any of the cognitive function measures, physical activity questionnaire, or physical function test, then further construct validity would be provided for MAPS as a functional-living measure in older adults. MAPSI and MAPSV scores were significantly correlated with the measure of processing speed and spatial visualization. The physical function score was also significantly correlated with MAPSI scores. The remaining measures of cognitive function and the physical activity questionnaire were not found to be associated with functional-living, as measured by MAPS, due to several limitations in the measures used. Wearing the activity monitors during any 3-day combination of days provided reliable MAPS data. Results of the study provided evidence of construct validity for MAPS as a functional-living measure.

Previous research has shown an inverse relationship between age and the relative intensity at which ventilatory threshold (VT) occurs in adolescent boys. However, no study has examined the effect of maturity status on VT in the differences in boys from the onset of puberty, adolescents. The purpose of this study was to compare VT among adolescent boys of different maturational groups. Methods: For this study, moderately active adolescent male participants (14 ± 3 y) completed this study. Maturational status of the participants was determined via years from peak height velocity (PHV), which is an estimation of somatic maturity status derived from age, standing height, seated height, body mass, and leg length. Participants were categorized into PRE- (lesser than 1 year till PHV), PERI- (within 1 year of PHV), and POST-PHV (greater than 1 year past PHV). All participants completed a ramp graded exercise test on a cycle ergometer. During the test, participants were given a three-minute warm-up with no resistance before starting at a workload of 30 watts which increased at a rate of 1 watt every 3 seconds until volitional fatigue. Throughout the test, oxygen consumption (VO2) and ventilation were measured. VT was determined, as a percentage of VO2max, from the ventilation versus VO2 graph using the maximal deviation method. Differences in VT between maturational groups were examined using one-way ANOVA. Results: A significant (F=5.36; p=0.014) difference in VT among maturational groups was found (Appendix A, Figure 2). Post hoc analysis revealed that PRE (p=0.029) and PERI (p=0.009) had VT occur at a significantly greater relative percentage of VO2max than POST. However, no significant (p=0.970) differences were found between PRE and PERI (Appendix A, Figure 3). Conclusion: Adolescent males in PRE and PERI demonstrated higher VT as a percentage of their VO2max compared to POST. This finding suggests the differences in the delayed switch from aerobic to anaerobic metabolism during incremental exercise in adolescent boys who are PRE and PERI.

The purpose of this dissertation was to evaluate the effects of changing body position on the execution of the isometric mid-thigh pull (IMTP). Furthermore, while there is evidence to suggest that there is an effect of familiarization on performance of maximal strength tests, there has been no known research evaluating the effect of learning on the IMTP. The effect of familiarization was assessed by evaluating changes in variables obtained from the IMTP. Subjects did not statistically improve over the five IMTP testing sessions, regardless of the body position used, or if subjects had previous experience with weightlifting derivatives. This may indicate that little familiarization is needed for subjects to perform the IMTP before acute increases due to learning stabilize. When body positions were compared, there were differences in force production whether subjects had or did not have experience with weightlifting movements. The magnitude of difference between body position was affected by weightlifting movement experience; lifters with >6 months experience with weightlifting had larger differences in force production between position. Average muscle activation for a variety of muscles, evaluated with surface EMG, appeared to differ between body positions, although these positions are idiosyncratic to experience level. In particular, lumbar erector spinae activation was higher in the bent position for both groups, which may have implications for low back injury risk.In entirety, it appears that if maximizing force production is the goal, the upright positon is optimal. Furthermore, the differing body positions have meaningfully different effects on how 3 much individual muscles are activated between positions. Lastly, substantial familiarization does not appear to be necessary before subjects perform the IMTP.

The purpose of this dissertation was to determine if a there was a dose-response relationship across an NCAA Division I men’s soccer season. Specifically, this dissertation serves to: 1.) assess the validity of duration measurements that have previously been used to calculate session RPE during competitive matches, 2.) determine the degree and magnitude of change in intermittent endurance performance across a season and to observe how change in endurance relates with training load, 3.) determine the degree and magnitude of change in strength and explosiveness across a season, and to see how these strength changes relate to training load. 1.) Minutes played were found to be the most accurate duration for calculating session RPE during men’s NCAA Division I soccer matches. 2.) Endurance performance, measured using the Yo-Yo IR1, increased by an average of 14 percent from pre to post season. Furthermore, a large, negative relationship was observed between training load and change endurance performance. These relationships suggest that excessive accumulation of training load can impair endurance performance. The congested NCAA DI match schedule may make it difficult to prevent excessive training loads. 3.) When players were grouped by amount of college soccer experience (upper and underclassmen), upperclassmen jumped significantly higher than underclassmen during the preseason. Moreover, the upperclassmen maintained or increased jump height from pre to post season, while underclassmen experienced a general decrease in jump height from pre to post season. Moderate relationships indicate a positive relationship between training load from resistance training and changes in strength. Likewise, these same relationships strengthened in the players who received more playing time during matches. Taken together, the high numbers of moderate relationships indicate a high level of individual variability. Dose-response relationships with strength variables were not sufficiently established. The overall findings of this dissertation provide evidence that subjectively and objectively monitoring training load and soccer-related performance variables can assist coaches in making decisions that will promote the welfare of their team.