Cellular maturation (differentiation) and cell death (apoptosis) are two vital processes shared by virtually all mammalian cells types. Although these two events have disparate outcomes, recent evidence indicates their execution may involve similar cellular mechanisms. Considered the primary effectors of apoptosis, a family of proteolytic enzymes known as caspases become activated in response to upstream apoptotic signalling, and are responsible for cleavage of structural and regulatory proteins, nuclear degradation and DNA fragmentation, and cell blebbing. While these enzymes have a well-defined role in death, current research suggests their activity is necessary during the differentiation of several cell types including skeletal muscle. However, it is currently unknown how this pro-apoptotic environment is regulated to promote differentiation. A long known mediator of apoptotic signalling, the mitochondria, has recently been shown to affect apoptosis through changes to its morphology. Mitochondrial division (fission) and fusion are necessary for maintaining normal cellular function, although fission contributes to apoptotic signalling. In this study, we examined the mechanisms which lead to caspase activation during skeletal muscle differentiation, and determined the importance of mitochondrial fission to this process. It was hypothesized that typical mitochondrial-mediated apoptotic signalling would be responsible for activating caspases during myogenesis, partly due to increased fission. C2C12 mouse skeletal myoblasts maintained in culture were induced to differentiate by switching to low growth-factor media and collected at various time points during the differentiation process. Activity levels of caspases-2 and -3 transiently increased 51% and 2.5-fold, respectively, 1.5 days after inducing differentiation (p<0.05). No changes were observed in the activity levels of caspases-8 and -9. Although whole-cell levels of Bax and PUMA increased 16% and 21% (p<0.05), respectively, prior to the spike in caspase activity, levels of mitochondrial-Bax were matched by Bcl-2, resulting in no change to the mitochondrial Bax:Bcl-2 ratio early during differentiation. This ratio indicates the susceptibility of the mitochondria to release pro-apoptotic factors, and was associated with decreased cytosolic levels of Smac and cytochrome c by 63% and 75%, respectively, early during differentiation (p<0.05). Levels of the anti-apoptotic proteins Bcl-2 and ARC increased (p<0.05) as caspase activity diminished, possibly supporting their role in ensuring temporary caspase activation. Pharmacological inhibition of caspase-3 resulted in reduced differentiation as indicated by decreased myotube development and cell fusion events. These morphological changes were associated with decreased protein expression levels of the myogenic transcription factor myogenin (p<0.05), and the mature-muscle marker myosin (p<0.05). Likewise, chemical inhibition of caspase-2 activity impaired myotube development, cell fusion, as well as expression of myogenin (p<0.05) and myosin (p<0.05) similar to the inhibition of caspase-3. Finally, reducing mitochondrial fission with a chemical inhibitor of Drp1 function (mdivi-1) also prevented myotube development, resulting in undetectable levels of myosin expression and a 94% drop in cell fusion events. However, these effects were not due to decreased caspase activation. In contrast to our hypothesis, these results support the notion that mitochondrial apoptotic signalling is likely not responsible for inducing caspase activity during myogenesis. Furthermore, we report that mitochondrial fission is necessary for proper skeletal muscle differentiation, likely through its contribution to mitochondrial network morphological changes associated with myotube formation.

Purpose: This investigation evaluated the effects of a high-load (50% body weight) eccentric exercise training protocol on reloading myofibrillar damage in soleus (SOL) and extensor digitorum longus (EDL) muscles in rats following 7 days (d) of hindlimb suspension unloading (HSU). Methods: 48 female Sprague-Dawley rats were randomly stratified to four experimental groups; exercise + hindlimb suspension unloading (ExHSU), hindlimb suspension unloading (HSU), exercise (Ex) and control (C). The ExHSU and Ex groups underwent a high-load eccentric exercise protocol for ~2.5 weeks. Following exercise training, the ExHSU and HSU groups underwent 7 d of hindlimb suspension unloading and a subsequent 16-19 h reloading period. ANOVA was used to determine significance between groups for the following variables: body weight (BW) across time, BW at sacrifice, Glucose-6-phosphate dehydrogenase (G-6-PDH) activity, fiber area, fiber area to body-weight ratio, % myofibrillar damage, SOL and EDL wet, dry and wet-weight to body-weight ratios, % interstitial area, adrenal weights and adrenal weight to body-weight ratios, tibia lengths and tibia bone mineral content. Results: ANOVA revealed no significant differences (p > .10) between the ExHSU and HSU groups for BW at sacrifice, fiber area, fiber area to body-weight ratio, SOL and EDL wet, dry and wet-weight to body-weight ratios, adrenal weights and adrenal weight to body-weight ratios and tibia lengths and bone mineral content. Yet a post analysis t-test revealed a significantly higher % of myofibrillar damage in the HSU vs. the ExHSU group. Further, G-6-PDH activity and % interstitial area approached significance (p = 0.134 and p = 0.152, respectively). Conclusions: The high-load eccentric exercise training protocol prior to HSU attenuated the % of myofibrillar damage during reloading. Further, the % of interstitial area and G-6-PDH activity tended to be smaller in the ExHSU group vs. the HSU group. Therefore, eccentric exercise prior to HSU may elicit a repeated bout effect and attenuate the amount damage incurred by the muscle during reloading. Additionally, this investigation was the first to demonstrate increased G-6-PDH activity with reloading myofibrillar damage.

Obesity is the number one public health concern in the United States, and is more prevalent in African-American women and those from lower socioeconomic groups. However, many primary care physicians do not feel confident in their ability to assist patients in weight management. Thus the challenge for physicians is to provide patients better assistance with weight management. The purpose of the study was to examine the efficacy of a primary care-managed weight loss program on weight reduction and cardiovascular fitness in overweight/obese women. Participants were randomized to intervention (n=54; Age: 44+12 yrs) or standard care (n=62; Age: 44=12yrs) and followed for 6 months. Intervention included monthly physician visits to address issues concerning diet, exercise, barriers, and motivation. Those in intervention experienced moderate weight loss after 6 months (Intervention: 216.89+48.38 to 208.86+42.11; Standard Care: 222.01+ 37.67 to 221.95+38.81, p=0.004). However, further analysis revealed the magnitude of weight loss appears to be dependent on the physician responsible for the delivery. Pearson correlation coefficients revealed the magnitude of weight loss was significantly associated with a change in waist circumference, 1-min heart rate recovery, and systolic blood pressure. In conclusion, this study reports a moderate weight loss following a physician directed program in overweight/obese women from lower socioeconomic groups. Independent of intervention moderate weight loss was associated with a reduction in other cardiovascular risk factors including BMI, heart rate recovery, blood pressure, and waist circumference.

The autonomic nervous system (ANS) modulation of the heart is of clinical importance because of its relevance to risk of life threatening arrhythmic events. Decomposition of heart rate variability (HRV) has been used to quantify ANS control of the heart. The traditional method for frequency analysis has involved the use of fast Fourier transformation (FFT). However, heart rate data typically violate assumptions of the FFT. Therefore, the assessment of HRV may benefit from other, potentially more suitable, mathematical approaches. For example, the discrete wavelet transformation (DWT) appears to have promise with respect to its ability to discriminate between healthy and diseased populations. Therefore, the purpose of this thesis was to examine the extent to which the FFT can discriminate between a control group and heart failure patients (CHF) in comparison to DWT. Seven CHF (mean +/- standard deviation, age: 51.9 +/- 17.6 yrs) and eight age-matched controls (49.5 +/- 17.9 yrs) were evaluated. HRV was evaluated during 5 minutes of supine spontaneous breathing (SB) and supine paced breathing (PB) (0.2Hz). The ECG data were sampled at 200 Hz, converted to heart rate tachograms, and subjected to frequency analysis via FFT and DWT. The FFT approach did not reveal group differences in HRV, while the DWT revealed group differences in LF/HF during SB (p<0.05) and PB (p=0.053). With respect to breathing condition, only the FFT revealed that PB resulted in a decrease in low- to high-frequency ratios (p<0.05), and an increase in standard deviation of normal R-R intervals. These results support further consideration of both methods of analysis, as they each appear to provide unique information about HRV.

PURPOSE: To examine the effect of L-Aspartic Acid (L-Asp) supplementation on short-term arm-crank power (i.e. W·min^-1) and exercise-induced hyperammonemia in two gender-specific investigations. METHODS: The male investigation (MALE) used nine highly-trained intercollegiate water polo players (WP) and nine moderately-trained college students (MOD); the female investigation (FEM) used 18 recreationally-trained college students. All exercised to exhaustion on two occasions following counterbalanced double-blind ingestion of 12.5g x 2 of L-Asp or placebo (P). The warm-up phase began at 25 W·min^-1 and increased in 25 W·min^-1 stages every 30 seconds (constant 100 rpm). Performance began (i.e. the subjects turned the crank 'as fast as possible for as long as possible') with stage completion of rating of perceived exertion of 17 (6-20 scale) in MOD and FEM and at the 4-minute mark (200 W·min^-1) for WP. Individual warm-up time in session 1 for MOD and FEM was used as warm-up time for session 2, respectively. Venous blood samples were drawn at 3 minutes post-exercise and assayed for blood NH₃ [μM/L]. A 2 x 2 ANOVA with repeated measures was used for MALE, and a one-way ANOVA with repeated measures for FEM, with Tukey's t-test for post hoc differences. RESULTS: Blood NH₃ [μM/L] decreased with L-Asp (vs. P) in WP (241.0 ± 18.4 vs. 200.6 ± 20.5, p < 0.01) and MOD (219.7 ± 20.8 vs. 185.6 ± 27.5, p < 0.05). Performance power (W·min,^-1) with L-Asp improved (p < 0.01) in WP (270.2 ± 19.7 vs. 227.6 ± 14.3) but not (p > 0.05) in MOD (220.1 ± 9.1 vs. 204.4 ± 8.3). There was no treatment effect in FEM. CONCLUSION: These results suggest that 12.5 g x 2 QD of L-Asp reduces hyperammonemia and enhances short-term power in intercollegiate water polo players. Conversely, in MOD and FEM, 12.5 g x 2 QD of L-Asp does not attenuate exercise-induced hyperammonemia sufficiently to improve power.

Four experiments presented here investigated the task demand relationship of intertrial variability (IV) and regulatory conditions (RC), on the outcome and movement changes that occurred with dart throwing practice. The four tasks included: (1) a stationary target with one location (closed w/no IV), (2) a stationary target with five possible locations (closed w/IV), (3) a moving target with one movement pattern (open w/no IV), (4) a moving target with five possible movement patterns (open w/IV). After each throw, the X, Y coordinates of the dart and the target were recorded to calculate radial error (RE). Kinematics was recorded using an eight-camera motion system with markers on the upper body, throwing arm, and dart. Novice participants performed 160 throws on each of 3 days. Results for all four tasks indicated that the RE decreased significantly (p< 0.05) across trial blocks, at a different magnitude and rate for each task. The displacement patterns of the wrist, elbow, and shoulder indicated changes in movement coordination as novices practiced their respective tasks. During the three days of practice, learners became more consistent in the pattern used. The displacement at the elbow was significantly different from the shoulder and wrist for the two consistent tasks, while the variable tasks revealed the elbow and wrist to be similar. Analysis of the joint-linkage cross-correlations showed the elbow-wrist linkage to be significantly different from the elbow-shoulder and the shoulder-wrist linkages, for all four experiments. These observations suggested that the subject controlled the degrees of freedom at the shoulder, while the elbow and wrist remained linked throughout practice. Closer analysis of the magnitude of the changes indicated an inverse relationship between the movement coordination and outcome changes. Large changes in the movement pattern resulted in small changes in the outcomes and vice versa. The results of these experiments provide evidence that environmental context (EC) affects how one performs, and what changes occur in the outcome scores and movement coordination, but the magnitude of these changes presents differing information regarding skill acquisition. Overall, the results indicated the amount of IV in the EC had the greatest effect on the performance.

The purpose of this study was to examine the interrelationships among gender, perceptions of peer, parent, and teacher support, perceived value and meaningfulness, perceived competence, and the intention to be physically active within a proposed model. Female and male students (N=801) enrolled in a traditional multi-activity physical education class responded to a 52-item questionnaire addressing the constructs in the model. Structural equation modeling, using LISREL, was used to identify the relationships among the constructs. Gender differences emerged in this model through direct paths as well as indirect paths among these variables. Girls were more influenced than boys by their perceptions of support of significant others. Indirect effects of gender on value and meaningfulness, gender appropriateness, perceived competence, as well as engagement in physical education indicate that these variables influence girls' intention to participate more so than boys'. Overall, the model supports previous studies that have explored these variables independently. It also offers support for the importance that physical education plays in teaching children to reject physical inactivity and adopt and maintain a healthy lifestyle.

Age is associated with deterioration in physical function (PF) and health-related quality of life (HRQL). Recent investigations suggest that a decrease in function may have a greater impact on perceived activities of daily living (ADL) competency in women than in men. The purpose of this investigation was to test the hypothesis that the association between PF and HRQL among older adults is influenced by gender. We examined 108 older adults aged 60 years or older, for PF (Continuous Scale-Physical Function Performance test (CS-PFP10) and Functional Status Index (FSI)) and HRQL (SF-36). In order to address this question we assigned subjects to fitness categories according to FSI and CS-PFP10 scores and tested for gender by fitness category interactions on HRQL. Moreover, we examined the relationship between total CS-PFP10 scores and the PCS-component of the SF-36 as well as total FSI scores and the PCS-component using linear, logarithmic, and power curves. Furthermore, we examined the correlation between total FSI and total CS-PFP10 in men and women. There were main effects of gender on physical self-reported and performance-based measures of PF indicating lower function in women as compared to men. The results indicate that self-reported and performance-based PF scores were positively associated with HRQL in men and women; however, the strength of the association was greater in men (R² ranging from 0.57-0.61) than in women (R² ranging from 0.17-0.44). Furthermore, the association between CS-PFP10 scores and FSI scores was stronger in men (R²= 0.64) than in women (R²= 0.47). These data suggest that PF explains more of the variance in physical constructs of HRQL in older men as compared to older women, and that a woman's HRQL is more tightly matched to her perceived functional ability than to her actual performance of ADL-based tasks. These findings underscore the complexity of the manner in which gender and PF interact with HRQL, and suggest the need for further research to clarify the most appropriate modeling techniques for understanding gender, function, and HRQL in later life.

Childrens physical inactivity is becoming an important health concern, and it has been suggested by professionals that school programs can be important in the effort to increase activity levels. Physical education specialists cannot achieve the goal of significantly increasing childrens activity in isolation, and it is apparent that whole school programs at the elementary level have the potential to foster active lifestyles. If those programs are to be successful, all school personnel must play a role, so it is important to find ways to facilitate their involvement. The purpose of this study was to use collective efficacy as a framework to examine elementary classroom teachers and principals perceptions about integrating physical activity into classroom lessons. Participants were 314 elementary teachers and 38 elementary school principals. They completed a survey to assess their physical activity patterns, willingness to integrate physical activity, and role preparedness. Participants also rated the influence of sources of information about efficacy, and the strength of individual and collective efficacy. Based on survey responses, 21 teachers and 12 principals were purposively selected for interviews to represent individuals with high and low efficacy. The interviews focused on their perceptions of barriers and enablers to movement integration. The participants acknowledged the importance of childrens physical activity and generally indicated they would be willing to integrate movement into classroom activities to some degree. Willingness to integrate was related to both individual and collective efficacy, but personal involvement in physical activity was not. Although there was a strong relationship between individual and collective efficacy, there was evidence that those variables are distinct and that collective efficacy varied by school context. Mastery experiences were most influential in predicting strength of individual efficacy, while institutional environment was the strongest predictor of collective efficacy. The three themes that emerged from the analysis of the qualitative data reflected the belief that (a) effective management is essential to successfully movement integration, (b) extensive inservice training would be needed, and (c) provision of administrative support and inclusion of physical activity in the accountability system are necessary if teachers are to be committed to integrating movement.

The purpose of the study was to examine the influence of teaching approaches on thoughts and practice behaviors of students, and how those thoughts and behaviors affect transfer of learning. First, a self-report instrument for assessment of cognitive processes that meditate motor skill outcomes was validated. The cognitive processes included prior knowledge usage, self-efficacy, critical thinking and attention-concentration. University students who had taken a physical activity class (N=409) completed the questionnaires. Three out of the initial four subscales were confirmed as fitting the data. In a university golf activity class, students were assigned into three groups for instruction to learn a golf-pitching task: guided discovery (scaffolded movement challenges using task cards to learn movement concepts), model group (students were presented concepts and shown a correct model) and a control group (received no information except the initial basic instruction the other two groups also received). Instruction lasted six days. Skill performance scores, form scores and self-report cognitive measures (cognitive processes questionnaire and strategies students used to be successful) were recorded. Results indicated that it was the lower-skilled students were responsible for improvements over time. Students used different strategies depending upon the instruction they received. Students in the trial and error used attentional strategies, those in the correct model reported that it was the technique related to posture and grip that helped and the guided discovery group clearly concentrated on applying concepts to be successful. However, no differences in transfer were evident. It is possible that guided discovery students did not have enough time to translate their understanding into outcomes. The results of the study provide evidence to support a mediating process perspective framework for understanding the links between teacher and student variables, and student variables and outcomes. Researchers should continue to design studies to explain how different instructional conditions and students variables elicit different cognitions and strategy use from students. In the future, it is important to investigate when and under what conditions certain behaviors and thoughts are elicited by the instructional approach will lead to more successful performance on skill and transfer tests.