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The circadian rhythm is a 24-hour cycle present within most biological systems that is controlled by the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is responsible for synchronizing the peripheral "clocks" present in other tissues so that all rhythms, such as heart rate, body temperature, and hormone secretion, are functioning together. As most systems experience a circadian rhythm, physical performance likely does as well. Previous studies have investigated time of day effects on maximal strength, power, and endurance performance, however, factors (e.g., sex, chronotype, age, etc.) have not clearly been distinguished. Additionally, body temperature has been suggested to be the primary mechanism behind time of day variation, but there have been studies to suggest that this is not the only mechanism that impacts potential differences. Additionally, studies to date lack female participants, despite potential differences between sexes. Therefore, this series of studies aimed to determine optimal time of day for maximal strength and power activities. It also aimed to examine sex differences, and the effect of chronotype and body temperature on performance. To do this, 3 studies have been conducted. First, a maximal effort sprint test on a non-motorized treadmill was conducted in a sample of recreationally active males and females. Second, a reliability study was conducted to establish a protocol that could assess maximal strength and endurance during the same assessment. This protocol also can be used in any population. Lastly, this protocol was then used to assess time of day effects on maximal strength and critical force (a theoretical sustainable force output) at different times. This study used a sample of both males and females as well to evaluate sex differences.

<p>Regular physical activity for people with spinal cord injury (SCI) has been related to numerous benefits, yet half of this population remains inactive (Martin Ginis et aI.,2010). The SCI community desires useful physical activity infonnation (Boyd & Bardak, 2004). It has been suggested that Canada's Physical Activity Guide for Adults Living with SCI (CPAG-SCI) be created (Martin Ginis & Hicks, 2007). This study sought to detemline what people with SCI would find useful in CP AG-SCI and to establish effective means for providing infonnation to maximize thoughts about being physically active. Firstly, 78 people with SCI (M(age)=45.06) were asked what content to include in CPAG-SCI and how to present it. Participants indicated that physical activity knowledge, motivational infonnation, safety and health infonnation, sources of infonnation and social support, and self-regulation infonnation were desired. CPAG-SCI as a booklet or interactive website was preferred (both 43.6%), text with pictures (83.3%), photographs (57.7%), bright colours (48.7%), simple messages (61.5%), and a calendar pull-out (70.5%). Secondly, the effectiveness of an experimental vignette aimed at changing physical activity social cognitions was explored. Based on the Health Action Process Approach (Schwarzer, 1992; 2004), participants were classified as in the motivational (n=32, M(age)=45.31) or volitional phase (n=47, M(age)=43.36), and then randomly assigned to an experimental or control vignette exposure condition. Social cognitions were measured one-week before, and immediately following, exposure to the vignette. Repeated measures ANOVAs showed that social cognitions generally decreased in those exposed to the experimental vignette, with coping plans approaching a significant decrease among those in the motivational phase (t(17) =2.10, p<.05). Exploratory analyses suggest that perceived similarity to the vignette character may be a key variable contributing to the ineffectiveness of the experimental vignette. Overall, it is suggested that physical activity vignettes in CPAG-SCI not target social cognition change.</p> <p>Keywords: spinal cord injury, physical activity, vignette, perceived similarity, social cognitions</p> / Master of Science (MS)

<p>Participation in exercise-based cardiac rehabilitation is a fundamental component for recovery and secondary prevention efforts following a cardiac event (Smith et aI., 2006). However, despite the known benefits of regular exercise for cardiac patients (Jolliffe et aI., 2001) and the ever-increasing availability of cardiac rehabilitation and related programs, individuals affected by cardiovascular disease continue to demonstrate poor attendance and follow-up adherence to exercise programming; this is particularly true for female participants (Daly et aI., 2002; Halm et al., 1999, Woodgate & Brawley, 2008). Previous research has shown self-efficacy to be a reliable and strong predictor of exercise adherence in both the general and cardiac rehabilitation populations. Using social cognitive theory (Bandura, 1986, 1997,2001), the present study investigated several socially-mediated perceptions that were theorized to predict self-efficacy, and in tum, its relationship to adherence to cardiac rehabilitation programming. In particular, this study was designed to investigate proxy efficacy and a newly- proposed socially-mediated efficacy construct (instructor support efficacy) and the relations between those variables, self-efficacy and exercise adherence within the cardiac rehabilitation setting. It was hypothesized that proxy efficacy for self-regulation and instructor support efficacy measured during the third week of cardiac rehabilitation would independently predict self-efficacy for self-regulation at week 9 of cardiac rehabilitation. It was also hypothesized that instructor support efficacy at week 3 of cardiac rehabilitation would be a stronger predictor of self-efficacy for self-regulation at week 9 of cardiac rehabilitation among women compared to men. Lastly, the study aimed to investigate proxy efficacy, instructor support efficacy and self-efficacy as predictors of exercise class attendance and adherence during participation in the cardiac rehabilitation program. Sixty cardiac rehabilitation participants (of which approximately 73% were male) who were enrolled in a hospital-based cardiac rehabilitation program completed assessments for self-efficacy for self-regulation, proxy efficacy for selfregulation, proxy efficacy for in-class exercise and instructor support efficacy at weeks 3 and 9 of program participation. Exercise attendance and exercise prescription adherence records were collected (at week 15 of program participation) using attendance records and exercise logbooks from the cardiac rehabilitation centre. In general, scores for all variables of interest were relatively high. Consistent with the first hypothesis, proxy efficacy for self-regulation and instructor support efficacy measured during the third week of cardiac rehabilitation independently predicted self-efficacy for self-regulation at week 9 of participation in the cardiac rehabilitation program. However, contrary to the hypotheses, when sex was investigated as a moderator of the instructor support efficacy - self-efficacy relationship, instructor support efficacy at week 3 did not predict self-efficacy for self-regulation at week 9 for either women or men. Finally, self-efficacy for self-regulation and proxy efficacy for in-class exercise independently predicted exercise class attendance between weeks 3-9, but no other significant predictors were found for exercise class attendance or program adherence throughout the remainder of the program. The findings from the present study provide a promising starting point in the development and assessment of instructor Support efficacy within the cardiac rehabiliation population.</p> / Master of Science (MS)

<p>Self-regulation refers to the ability to override one behaviour, thought, or emotion<br />and replace it with another (Baumeister & Heatherton, 1996). Baumeister et ai. (1998)<br />propose that self-regulation is governed by a form of strength that varies from person to person and can be depleted by engaging in tasks that require self-regulation. Although self-regulation strength can be depleted, it may also be replenished through rest and other hypothesized mechanisms. Positive emotion has been suggested as a way to replenish depleted self-regulatory reserves (Tice et aI., 2007). The purpose of the CUlTent study was to investigate the effects of listening to self-selected uplifting music on positive emotional states and the effect of varying positive emotional states on self-regulatory strength depletion patterns. It was hypothesized that the group that listened to a selection of prefened music would show an increase in positive emotion on the PANAS measure and that the positive emotion induction would serve as a replenishment of self-regulation, which would lead to amelioration of depletion effects on a handgrip squeezing exercise performed after this induction. The study employed a between subjects, repeated measures design. Participants were 90 sedentary university students (Mage =22.90 ± 7.18) who were randomly assigned to one of three conditions; (Stroop) Depletion/Music (emotion induction), Depletion/No Music (quiet rest control), or No Depletion/No Music (no depletion control and quiet rest control). After controlling for initial positive emotion scores, ANOVA results revealed that participants showed significantly higher scores on the positive emotion scale of the PANAS, F(2,87) = 7.84, p < .01. 112 =.73 after listening to music than engaging in quiet rest. The results further illustrate that the change from pre- to post- manipulation in raw mean scores for each condition did not differ significantly in the length of time that participants held onto the handgrip during the endurance trial at 50% MVC, F(2,87) = 0.30, p =.74, ,,2 = .01. After 18 participants were eliminated due to questionably low (:=:; 5) RPE ratings on the pre-test, the ANOVA was completed again, and no significant differences emerged, F(2,68) = .68, p = .51, ,,2 = .02. Although the results do not demonstrate that positive emotion has an impact on selfregulatory<br />strength depletion patterns, the current findings are discussed with respect to previous research done by Tice et al. (2007) and in light of Fredrickson's broaden and build theory and limitations. Further research is warranted to gain a better understanding<br />of the relationship between music, positive emotion and self-regulation for exercise.</p> / Master of Science (MS)

<p>Twelve participants performed a bimanual coordination task with the hands in different force field environments. Both in-phase and anti-phase coordination modes were examined. Mean relative phase absolute error measurements represented how accurate the phase relationship was, and the standard deviation of relative phase indicated how stable the coordination mode was. When the fingers were being moved in the same force environments, coordination was more accurate and stable, compared to when the hands were placed in mismatched force environments. Having one hand in a velocity dependent force-field produced less accurate coordination than when one hand was in a position dependent force-field. When coordinated movements were performed with at least one hand in viscous force-field environment, reduced coordination stability was observed, especially during anti-phase movements. There are several spatial, biomechanical and neuromuscular constraints that could have influenced coordination performance. The proposed mechanisms that affected coordination included the differences in neural compensation for different types of force-fields. As shown in previous studies, elastic loads generated later onset of EMG activity whereas viscous loads generated a higher rate of force production. The inability of the extensors muscles to overcome the load resistance in the viscous force-field affected coordination. These results support a two-tiered extension of the HKB model of bimanual coordination.</p> / Master of Science in Kinesiology

<p>Paralyzed skeletal muscle undergoes several changes after spinal cord injury (SCI) that lead to alterations in contractile properties and a decrease in fatigue resistance. In this thesis, SCI-induced changes in the muscle length-tension relationship were explored first through the identification of the optimal joint angles for force generation in the ankle dorsiflexor and plantarflexor muscles. The length-tension relationship in the dorsiflexor muscles was not found to differ between SCI and able-bodied (AB) participants, while the plantarflexor muscle group showed a significant shift to shorter muscle lengths (and thus smaller joint angles) for force generation after SCI.<br /><br />In the second part of this thesis, muscle fatigue characteristics in the ankle dorsiflexors were examined to determine if a decline in muscle excitability contributed to increased muscle fatigue after SCI. The protocol consisted of a 2 minute trial of intermittent tetanic bursts at 30Hz delivered to the peroneal nerve. There were no changes in M-wave amplitude or area observed over the course of the fatigue trial, despite significant loss in force generating capacity, suggesting the maintenance of muscle excitability during fatigue. Participants with SCI showed a greater degree of fatigue than the AB controls, with a decline of 57% and 43% in PT and IT, respectively. In comparison, the AB group showed an increase of 13% in PT and a decline of 22% in IT at the end of the fatigue trial ..<br /><br />In both studies, there were no significant differences in rates of muscle contraction or relaxation between SCI and AB groups, suggesting the possible preservation of type I muscle fibres in our participants. There was, however, a greater slowing of relaxation rate after fatigue in the SCI group, suggesting some potential impairment in Ca2+ re-uptake. Furthermore, there was a significant increase in the twitch-tetanus ratio noted in the SCI group in both studies, suggesting increased muscle stiffness and decreased elastic ~ compliance after SCI. These results have contributed to our understanding of the effects of paralysis on muscle properties; future work should focus on the identification of the :~ mechanisms of muscle fatigue after SCI and the possible role of spasticity in the maintenance of muscle contractile dynamics and fibre composition in paralyzed muscle.</p> / Master of Science (MS)