Master of Science / Department of Kinesiology / Craig A. Harms / An increased work of breathing during heavy whole body exercise can lead to respiratory muscle fatigue (RMF) and decreased leg blood flow. Heavy exercise also increases inactive limb and cutaneous blood flow. It is not known, however, how RMF affects inactive limb and cutaneous blood flow. Therefore, we tested the hypothesis that RMF during heavy exercise would reduce: 1) inactive limb blood flow, 2) inactive limb vascular conductance, and 3) inactive limb cutaneous blood flow. Twelve healthy men (23 ± 2 yrs) completed baseline pulmonary function tests followed by an incremental cycle test to VO[subscript]2[subscript]max. Subjects then cycled at both 70% and 85%VO2max (randomized) for 20 minutes. Subjects performed a second 85%VO[subscript]2[subscript]max test ingesting N-acetylcysteine (NAC) (1800mg), which has been reported to reduce RMF, 45 minutes prior the test. Maximum inspiratory pressures (P[subscript]Imax) were measured prior to and immediately following each exercise trial to determine RMF. During exercise, brachial artery blood flow (BABF) was measured via Doppler ultrasound and arm cutaneous blood flow was assessed by laser-Doppler flowmetry. Cutaneous vascular conductance (CVC) was calculated as flux/mean arterial pressure and scaled as % maximal CVC (sites heated to 46[degrees]C). Mean arterial pressure (MAP) was measured manually. Significant RMF occurred with 85%VO[subscript]2[subscript]max (12.8 ± 9.8%), but not with 70%VO[subscript]2[subscript]max (p>0.05). BABF significantly increased from baseline to end exercise in both conditions and was significantly lower (~18%) following the 85%VO[subscript]2[subscript]max test. The amount of RMF at 85%VO[subscript]2[subscript]max was inversely related to the change in BABF (r= -0.66, p<0.05). BA vascular conductance was significantly higher at end exercise at 70%VO[subscript]2[subscript]max compared to 85%VO[subscript]2[subscript]max (2.60 ± 0.73 vs. 2.00 ± 0.42 mLmin[superscript]-1mmHg[superscript]-1, resp.). The amount of RMF at 85%VO[subscript]2[subscript]max was inversely related to BA vascular conductance at end exercise (r= -0.80, p<0.05). Cutaneous vascular conductance was not different (p>0.05) between trials. With NAC, RMF was reduced and BABF was consequently significantly higher (~30%) compared to 85%VO[subscript]2[subscript]max. These data suggest that RMF during heavy whole body exercise decreases inactive arm blood flow and vascular conductance, but not cutaneous blood flow.

Children with complex heart defects lead sedentary lives that limit involvement in peer activities, impact their growth and development, and jeopardize their long-term health. The goal of this research was to better understand the factors that influence daily moderate-to-vigorous physical activity (MVPA), which is associated with physical and psychological health. The physical activity levels of 64 children (25 female, 5 to 11 years of age) with a single pumping chamber in the heart were measured by accelerometry. Fitness and gross motor skill measures and medical history information were analyzed to identify factors associated with MVPA participation. Increased activity was related to the use of antithrombotic medication, spring season of the year, better motor skill and male sex. Group and individual discussions further explored psychosocial influences on the children’s level of MVPA. The children indicated physical activity was primarily motivated by having fun and being with their friends, while other children being more skilled discouraged participation. Parents of children with complex heart defects had dramatically different perceptions. They believe their child’s activity is primarily influenced by the heart condition and report often feeling uncertain about which activities are appropriate for their child. Finally, sources of parental uncertainty were examined by comparing the physical activity advice provided by the cardiologist to parent reports of the child’s activity restrictions, a content analysis of published activity guidelines and interviews with paediatric cardiologists. Parent uncertainty about activity was supported by the lack of agreement between parent and cardiologist reports of medically necessary activity restrictions. Parent reports of vague or variable activity advice were reflected in the published literature and cardiologist perspectives on activity counselling. These results suggest enabling children with complex heart defects to achieve an active lifestyle may rest on ensuring that the child and parents have appropriate physical activity beliefs and expectations.

Children with complex heart defects lead sedentary lives that limit involvement in peer activities, impact their growth and development, and jeopardize their long-term health. The goal of this research was to better understand the factors that influence daily moderate-to-vigorous physical activity (MVPA), which is associated with physical and psychological health. The physical activity levels of 64 children (25 female, 5 to 11 years of age) with a single pumping chamber in the heart were measured by accelerometry. Fitness and gross motor skill measures and medical history information were analyzed to identify factors associated with MVPA participation. Increased activity was related to the use of antithrombotic medication, spring season of the year, better motor skill and male sex. Group and individual discussions further explored psychosocial influences on the children’s level of MVPA. The children indicated physical activity was primarily motivated by having fun and being with their friends, while other children being more skilled discouraged participation. Parents of children with complex heart defects had dramatically different perceptions. They believe their child’s activity is primarily influenced by the heart condition and report often feeling uncertain about which activities are appropriate for their child. Finally, sources of parental uncertainty were examined by comparing the physical activity advice provided by the cardiologist to parent reports of the child’s activity restrictions, a content analysis of published activity guidelines and interviews with paediatric cardiologists. Parent uncertainty about activity was supported by the lack of agreement between parent and cardiologist reports of medically necessary activity restrictions. Parent reports of vague or variable activity advice were reflected in the published literature and cardiologist perspectives on activity counselling. These results suggest enabling children with complex heart defects to achieve an active lifestyle may rest on ensuring that the child and parents have appropriate physical activity beliefs and expectations.

Master of Science / Department of Kinesiology / Brett J. Wong / Mechanisms underlying the cutaneous vasodilation response to local skin heating and whole body heating in humans remain unresolved. Although nitric oxide (NO) is known to contribute to these responses, it remains unclear as to the source of NO. Adenosine receptors induce vasodilation in many human tissues and may work, in part, through NO. As these receptors are also known to be located in the cutaneous vasculature, the studies contained in this thesis were designed to investigate a potential contribution of adenosine receptor activation to the rise in skin blood flow elicited by local skin and whole body heating. The study presented in chapter IV was designed to determine a potential role for adenosine receptors in contributing to cutaneous thermal hyperemia. Four cutaneous microdialysis sites were randomly assigned one of four drug treatments designed to elucidate the contribution of A[subscript]1/A[subscript]2 adenosine receptors during local skin heating. Each site was locally heated from a baseline temperature of 33°C to 42°C at a rate of 1°C/10 s and skin blood flow was monitored via laser-Doppler flowmetry (LDF). The data obtained from these experiments suggest A[subscript]1/A[subscript]2 adenosine receptor activation directly contributes to cutaneous thermal hyperemia. These data further suggest a portion of the NO response may be explained by A[subscript]1/A[subscript]2 adenosine receptor activation; however, a substantial portion of the NO response is independent of the adenosine receptor contribution. The study presented in chapter V was designed to determine a potential role for A[subscript]1/A[subscript]2 adenosine receptors in contributing to cutaneous active vasodilation. Four cutaneous microdialysis sites were randomly assigned one of four drug treatments, as above, and skin blood flow was monitored via LDF. Whole body heat stress, sufficient to raise oral temperature at least 0.8°C above baseline, was induced via water-perfused suits. The data obtained from these experiments suggest A[subscript]1/A[subscript]2 adenosine receptor activation does not directly contribute to cutaneous active vasodilation; however, a role for A[subscript]1/A[subscript]2 adenosine receptor activation is unmasked when NO synthase is inhibited. The data from this study further suggest that A[subscript]1/A[subscript]2 adenosine receptor activation may be responsible for a portion of the known NO component of cutaneous active vasodilation.

Master of Science / Department of Kinesiology / Brett J. Wong / Nitrate supplementation in the form of beetroot juice (BRJ) has been shown to increase nitric oxide (NO), where nitrate can be reduced to nitrite and NO through both nitric oxide synthase (NOS) independent and dependent pathways. We tested the hypothesis that BRJ would augment the NO component of cutaneous thermal hyperemia. Dietary intervention consisted of one shot of BRJ for three days. Six subjects were equipped with two microdialysis fibers on the ventral forearm and randomly assigned to lactated Ringer’s (control) or continuous infusion of 20mM L-NAME (NOS inhibitor). The control site was subsequently perfused with L-NAME once a plateau in the local heating response was achieved to quantify NOS-dependent cutaneous vasodilation. Skin blood flow via laser-Doppler flowmetry (LDF) and mean arterial pressure (MAP) were measured; cutaneous vascular conductance (CVC) was calculated as LDF/MAP and normalized to %CVCmax. Maximal vasodilation was achieved via local heating to 43°C and 54mM sodium nitroprusside infusion. There was a significant decrease in DBP after BRJ (Pre-BRJ:74 ± 1 mmHg vs. Post-BRJ: 61 ± 2 mmHg; p < 0.05) and significant reduction in MAP after BRJ (Pre-BRJ: 90 ± 1 mmHg vs. Post-BRJ: 80 ± 2 mmHg; p < 0.05). The initial peak and secondary plateau phase of cutaneous thermal hyperemia were attenuated at sites with continuous LNAME; however, there was no effect of BRJ on either the initial peak at control sites (Pre-BRJ: 76 ± 3%CVCmax vs. Post-BRJ: 75 ± 4%CVCmax) or L-NAME sites (Pre-BRJ: 60 ± 4%CVCmax vs. Post-BRJ: 59 ± 5%CVCmax) or the secondary plateau phaseat control sites (Pre-BRJ: 88 ± 4%CVCmax vs. Post-BRJ: 90 ± 4%CVCmax) or L-NAME sites (Pre-BRJ: 45 ± 5%CVCmax vs. Post-BRJ: 51 ± 3%CVCmax). The decrease in %CVCmax to L-NAME infusion during the plateau of local heating (i.e. post-L-NAME drop) was greater after BRJ (Pre-BRJ: 36 ± 2%CVCmax vs. Post-BRJ: 28 ± 1%CVCmax; p < 0.05). This resulted in a greater contribution of NOS to the plateau phase of local heating (Pre-BRJ: 57±3%CVCmax vs. Post-BRJ: 64±2%CVCmax; p < 0.05). These data suggest BRJ modestly improves NOS-dependent vasodilation to local heating in the cutaneous vasculature of healthy humans.

Eccentric exercise causes skeletal muscle damage, yet the acute cellular responses post-exercise have yet to be fully elucidated. To better understand the post-exercise response, heat shock protein (HSP) 72 content and nuclear factor-κB (NF-κB) activation where examined in Adult (A; 6 month) and Late middle-aged (LMA; 24 month) Fischer 344xBrown Norway rats. Animals were randomly divided into five groups (n=6): non-exercising controls (C), level (L) or eccentric (ECC) (-16°) running at 16m.m-1 and killed immediately post-exercise (0), 48 hours post-exercise (48). Following ECC, vastus intermedius (VI) from A and LMA showed more damage compared to L exercise. Neither age-group had significantly increased VI HSP72 content compared to C. Pooled results founded increased HSP72 content in ECC-48 compared to C (p<0.02). NF-κB activation in the VI was lower in LMA (p<0.001) and unchanged in WG when compared to AC. These findings suggest HSP72 is increased following eccentric exercise in the VI.

Eccentric exercise causes skeletal muscle damage, yet the acute cellular responses post-exercise have yet to be fully elucidated. To better understand the post-exercise response, heat shock protein (HSP) 72 content and nuclear factor-κB (NF-κB) activation where examined in Adult (A; 6 month) and Late middle-aged (LMA; 24 month) Fischer 344xBrown Norway rats. Animals were randomly divided into five groups (n=6): non-exercising controls (C), level (L) or eccentric (ECC) (-16°) running at 16m.m-1 and killed immediately post-exercise (0), 48 hours post-exercise (48). Following ECC, vastus intermedius (VI) from A and LMA showed more damage compared to L exercise. Neither age-group had significantly increased VI HSP72 content compared to C. Pooled results founded increased HSP72 content in ECC-48 compared to C (p<0.02). NF-κB activation in the VI was lower in LMA (p<0.001) and unchanged in WG when compared to AC. These findings suggest HSP72 is increased following eccentric exercise in the VI.

Doctor of Philosophy / Department of Human Nutrition / Mark D. Haub / Maximizing performance and results in competitive events is something that all athletes strive to achieve. Nutritional strategies have been developed to best optimize the likelihood of success in competitive events. While dietary protein was classically believed to be the key macronutrient in exercise performance, overwhelming evidence now supports the role of maximizing carbohydrate intake and availability in endurance performance. The role of carbohydrate intake prior to, during and after endurance exercise has been heavily studied and relevant literature will be discussed herein. This paper consists of three chapters and a summary related to carbohydrate intake and performance outcomes in endurance sports. While nutritional status surrounding the endurance events is discussed, this paper focuses on the ergogenic and metabolic effects of carbohydrates during the endurance bout. Chapter one serves as a literature review of carbohydrate administration during endurance exercise. Types of carbohydrates, their role as substrates in liver and skeletal muscle during exercise, and their effects on endurance performance are discussed. The role of carbohydrate on central factors of fatigue and motor output also are covered. Chapter two addresses the role of multiple carbohydrate supplements on cycling performance. The role of these supplements on blood glucose, insulin, lactate, and IGFBP-1 also are discussed. Chapter three addresses the effect of nutritional status prior to exercise on the ability of a carbohydrate mouth rinse to impart a performance enhancing effect. There were no treatment effects (p>0.05) of the type carbohydrate ingested, compared with placebo, on selected metabolic and performance outcomes. Likewise, there was no ergogenic effect of mouth rinsing, in the fasted or fed state, in moderately trained endurance cyclists.

Master of Science / Department of Kinesiology / Craig A. Harms / Expiratory flow limitation (EFL) during exercise can limit exercise tolerance. We have recently reported a high prevalence of EFL independent of sex in prepubescent children (Swain et al. 2010) that greatly exceeds that reported in adults. It is unknown how maturation and growth from pre- to post-puberty affects pulmonary function, specifically EFL, during exercise. The purpose of this longitudinal study was to investigate the changes in cardiopulmonary function from pre- to post-puberty in boys and girls. We hypothesized that EFL prevalence would decrease from pre- to post-puberty (with boys exhibiting a greater decrease than girls) and that the decrement could be explained by an increase in pulmonary function and a decrease in VE/VCO2. Twenty-one children (ages 12-16 yrs; 11 boys, 10 girls) were recruited from 40 prepubescent children who completed testing in our laboratory ~5 years ago. Subjects completed pulmonary function tests before and after an incremental exercise test to exhaustion (VO2max) on a cycle ergometer. EFL was determined using the percent tidal volume (VT) overlap method. Nineteen of the 21 subjects (10 boys, 9 girls; 90%) exhibited EFL pre-puberty, while only 7 of the 21 subjects (5 boys, 2 girls; 33%) exhibited EFL post-puberty. Of the subjects who experienced EFL post-puberty, all had experienced EFL pre-puberty. Boys had a significantly greater vital capacity (VC) than girls both pre- (~15%) and post-puberty (B: 4.73 ± 0.53; G: 3.80 ± 0.29 L). Maximal aerobic capacity (VO2max) significantly increased (~110% in girls and ~120% in boys) from pre- to post-puberty and was greater (p<0.05) in boys post-puberty (B: 2.76 ± 0.43; G: 1.94 ± 0.35 L/min). VE/VCO2 also significantly decreased (~13%) in both boys and girls. Post-puberty subjects regulated tidal breathing at higher lung volumes (greater ERV/FVC and lower IRV/FVC) during exercise compared to pre-puberty. None of the subjects experienced significant arterial desaturation pre-puberty or post-puberty. Our findings suggest that the prevalence of EFL declines as children mature from pre- to post-puberty, likely due to increases in lung size, decreases in VE/VCO2, and/or changes in breathing mechanics that are greater than increases in maximal ventilation that occur with increased pulmonary gas exchange.

Master of Science / Department of Kinesiology / Thomas J. Barstow / Purpose: Oxygen uptake (VO2) has been shown to be controlled by a nonlinear system, yet the VO2 response to ramp style exercise appears linear. We tested the hypothesis that an integrative model incorporating nonlinear parameter values could accurately estimate actual VO2 responses to ramp style exercise. Methods: Six healthy, men completed three bouts of varying ramp rate exercise (slow ramp (SR): 15 W/min, regular ramp (RR) 30 W/min, fast ramp (FR) 60W/min) and four bouts of extended-step incremental exercise, where each step lasted 5-15 min or until volitional fatigue on a cycle ergometer on separate days. The step-responses were then fit with a simple monoexponential starting at time zero (MONO) or allowing a time delay and using only the first 5 min of data (5TD). The resulting VO2 parameters from the step protocol were incorporated into an integrative model for the estimation of the VO2 response to each of the rates of ramp incremental exercise. The parameters from the actual and model ramp protocols were compared with 2 way repeated-measures ANOVAs. Results: Both Gain (G) and Mean Response Time (MRT) (or time constant) values increased significantly across work rate transitions (mean±SD; Gain:10.0±0.9, 11.6±1.1, 13.1±1.3, 17.6±3.3 ml O2/min/W; MRT:39.4±7.7, 54.0±5.4, 79.6±15.0, 180.1±56.2 s). Up to maximalVO2 the models over-estimated the actual VO2 response for FR (Gain: ACT 8.7±1.0, MONO 9.9±0.4, 5TD 10.3±0.3 ml O2/min/W). Up to 80% maximal VO2 the models accurately predicted the actual VO2 response across all ramp rates (Gain: ACT 10.7±1.1, 10.2±0.5, 9.2±1.0; MONO 11.0±0.8, 10.3±0.6, 9.2±0.5; 5TD 10.4±0.4, 10.2±0.3, 9.8±0.2 ml O2/min/W, values are listed SR,RR,FR). Conclusions: When variable parameter values (G and either MRT or time constant and time delay) were utilized by an integrative model, accurate estimations of the VO2 response to ramp incremental exercise were possible regardless of ramp rate (up to 80% maximal VO2). The increases in both G and MRT (or time constant) appear to balance each other to produce the quasi-linear VO2 responses.