Exercise induces morphological and metabolic adaptations that are highly specific to the mode of exercise training. These specific phenotypical changes are due to an equally specific molecular response that may depend on the activation and coordination intramuscular signaling pathways. Just as metabolic and morphological changes are influenced by the mode of exercise training, the signaling pathways that mediate exercise adaptation may also be directly related to the training status of skeletal muscle. For example, pre-conditioned skeletal muscle may exhibit a specific intracellular signaling response to an acute bout of exercise that is dependent on past training history. Both Akt (protein kinase B) and extra-cellular signal-related kinase (ERK 1 /2) have been shown to be phosphorylated in response to an acute bout of resistance exercise in human skeletal muscle and have been suggested to mediate the adaptive response to exercise. The purpose of this investigation was to examine the response of Akt and ERKI/2 to an acute bout of resistance exercise in three groups with distinctly different exercise training backgrounds. Twenty one subjects performed 3 sets of 10 repetitions of knee extension exercise at 70% 1-RM. The subjects consisted of a resistance-trained group (RE) (n=7), endurance trained group (END) (n=7) and a sedentary group (SED) (n=7). Muscle biopsies were taken from the vastus lateralis muscle before, immediately after, and 10 min post-exercise and were analyzed for phosphorylation of Akt and ERK1/2. ERK1/2 phosphorylation increased 47%, and 54% from pre-exercise to immediately post-exercise in the SED and RE groups respectively (p < 0.05). ERK1/2 phosphorylation increased 95%, 196%, and 47% from pre-exercise to 10 min post-exercise in the SED, RE, and END groups, respectively. (p < 0.05). The magnitude of ERK1/2 phosphorylation 10 min post-exercise was different between each group and may be linked to the group's training status. (p < 0.05) Akt phosphorylation decreased 42% and 37% from pre-exercise to immediately post-exercise in the SED and END group, respectively (p < 0.05). There was a 40 % increase in Akt phosphorylation from immediate post-exercise to 10 min post-exercise in the END group. In conclusion, training status appears to influence the magnitude and time course of activation of both Akt and ERK1/2 in response to an acute bout of resistance exercise. The immediate response of both ERK1/2 and Akt may play a key role in the adaptive response of skeletal muscle ultimately resulting in metabolic and morphological changes that are dependent on the past training history of the individual. / School of Physical Education, Sport, and Exercise Science

The American College of Sports Medicine advocates the use of a percentage of maximal oxygen uptake reserve (%VO2R) for exercise prescription purposes because it's thought to provide a close match with percentage of heart rate reserve (%HRR) than a given percentage of maximal oxygen uptake (%VO2max). However, some recent studies have challenged the validity of this matching. The purpose of this study was to assess the association of body mass index (BMI) with the matching of %HRR and %VO2R during graded exercise testing. The study sample included 626 subjects (281 men; 345 women); mean age of 45.5+11.7 years; mean BMI of 27.9+5.4 kg .m-2) who completed a maximal treadmill test to volitional fatigue using the BSU/Bruce Ramp protocol. The distribution of BMI measures within the sample was 31.4% <25; 38% between 25.0 and 29.9; 17.9% between 30 and 34.9%; 8.8% between 35 and 39.9%; and 3.1% were > 40 kg•m"2. Subjects were excluded from the analysis if they failed to achieve a peak RER > LO during the maximal exercise test, possessed pulmonary or cardiovascular disease (excluding hypertension), or incomplete/erroneous submaximal heart rate and/or V02 data that was unable to be retrieved from subject's existing file. Heart rate and VO2 data from minutes 3, 6, and 9 were converted into %HRR and %VO2R, with 3.5 ml•kg-'•min' serving to represent resting VO2. The relative exercise intensity for minutes 3, 6, and 9 represented 39.7 +12.2, 62.9 ± 15.6, and 80.8 ± 12.5% of VO2R, respectively and 43.1 f 12.6, 64.7 ± 14.9, and 83.5 + 10.6% of HRR. %HRR significantly overestimated %VO2R at each measurement point during the exercise test with mean differences 3.3, 2.0, and 3.8%, respectively (p<0.05). The association of BMI with the matching of %HRR and %VO2R was assessed by correlation with the difference the scores (AHRRVO2R) at each specified time during exercise test. Correlations for BMI and AHRRVO2R were -0.102, -0.175, and -0.231 for minutes 3,6, and 9, respectively (p<0.05). These results demonstrate a low association between BMI and the matching of HRR and VO2R. / School of Physical Education, Sport, and Exercise Science

The purpose of this study was to establish an exercise protocol that demonstrated a relationship between rest-interval duration and the exercise induced human growth hormone (hGH) response. Ten recreationally trained male subjects (23 ± 0.9 yrs) performed three leg extension trials on an Eagle — Cybex leg extension machine that consisted of 4 sets of 10 repetitions. The workload and volume was kept constant, but each trial had different rest-interval durations. Rest-interval durations between sets were at: 30 sec intervals (T-30), 60 sec intervals (T-60), or 120 sec intervals (T-120). Blood samples were obtained pre- and 0 — 30 minutes post-exercise and analyzed for lactate and hGH. All blood lactates rose significantly above baseline after exercise, with no differences in time of occurrence between trials. Blood lactates were significantly greater after the T-30 trials, compared to that of the T-60 and T-120 trials. There was no significant difference in hGH concentrations between trials. However, the data did suggest a relationship between rest-interval duration and the variability of hGH responses. The T-30 trials yielded significantly greater variation in hGH concentrations than the T-120 trials, and the T-120 trials showed significantly less variation than both the T-30 and T-60 trials. Although significant differences were found in these variations between trials, they did not prevent any significant differences in concentrations between trials from being found. In summary, the results of this study demonstrated an exercise related increase in lactic acid that had an inverse relationship to the length of the rest-intervals. hGH data on the other hand, did not show a relationship between rest-interval duration and the hGH concentrations. The connection between rest-interval duration and variability of hGH responses could possibly suggest that hGH values may have been significantly different if an exercise protocol higher in volume were utilized. Additionally, the results indicate that there is no direct relationship between blood lactate and hGH concentrations, as others have suggested. / School of Physical Education, Sport, and Exercise Science

Fibrinolysis is the process by which fibrin blood clots are dissolved. Fibrinolytic research is clinically relevant because decreased fibrinolytic potential is linked to increased risk of an ischemic event. Fibrinolysis is known to increase in response to aerobic exercise, however, few research studies have focused on the fibrinolytic response to resistance exercise. Furthermore, women are severely underrepresented in fibrinolytic research, and there are no current studies that focus on women and resistance exercise. Estrogen has been shown to affect basal fibrinolytic potential resulting in the need for fibrinolytic research focused on female subjects. Body composition is known to influence basal fibrinolysis leaving individuals with higher absolute amounts of body fat at risk for cardiovascular events due to decreased fibrinolytic potential. Little is known, however, about the influence of body composition on the fibrinolytic response to exercise. Purpose. The purpose of this study was to describe the fibrinolytic response to acute resistance training in young women, and further, to determine how body fat percentage affects fibrinolysis at rest and following resistance exercise. Methods. Twenty-three sedentary, healthy women (22.5 ± 4 yrs, 22.3 ± 3.0 kg•m 2) participated in the study. Body fat percentage and fat distribution were assessed using dual-energy X-ray absorptiometry (DEXA), and subjects were separated into two groups by body fat percentage: <30% (lean, n=12) and >30% (obese, n=11). Each subject performed 6 sets of 10 leg extension repetitions at an intensity associated with 70% of her one-repetition maximum. The two primary mediators of fibrinolytic potential, tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1(PAI-1), were assessed at baseline and immediately after exercise in venous blood. Results. tPA activity increased in response to acute resistance exercise (p<0.05), however, there was no significant change in PAI-1 activity (p>0.05). A significant main effect of group was observed, indicating the lean women had higher tPA activity (p<0.05) and lower PAI-1 activity (p<0.05) than the obese group. A significant time x group interaction indicated that the tPA response was blunted in the obese group (p<0.05). Conclusions. Fibrinolytic potential increases in response to acute resistance exercise in young women due to increases in tPA activity. Obese women demonstrate a decreased fibrinolytic potential at rest and following acute resistance exercise compared to lean women. Given the relationship between fibrinolytic potential and outcomes of cardiovascular disease, these physiological responses suggest that overweight women may be at elevated risk of an adverse cardiovascular event both at rest and during exercise. / School of Physical Education, Sport, and Exercise Science

Respiratory and metabolic patterns in response to variations in exercise workload (WL) and pedal frequency (RPM) were examined in 10 healthy males. Each subject performed WLs of low (L), moderate (M) and high (H) intensity, equivalent to 25%, 50% and 75% V02 m a x at 7 pedal frequencies (40, 50, 60, 70, 80, 90 and 100 RPM). ANOVA ( 3 X 7 design) indicated that WL and RPM had independent and significant effects on all respiratory and metabolic measures; i.e., the greater the WL and RPM, the higher the HR, V02, VC02, Ve, Fb, Vt, Vt/Ti, Vt/Te and Ti/TtQt and the lower the Ti and Te. However, analysis of the interaction effect revealed different response patterns for Fb, Vt, Ti, Vt/Ti, Vt/Te and Ve among the WLs. During L-WL, increases in RPM produced increases in Ve which were due to progressive increases in both Fb and Vt. However, during M-WL and H-WL, increases in RPM produced increases in Ve which were accomplished by a constant Vt and a progressive increase in Fb. My findings suggest that during low WLs, the signal for Vt is dependent on rate of contraction, while during M-WL and H-WL, the signal for Vt appears to depend on force of contraction and is independent of increasing RPM. When comparing the L-WL and M-WL, alterations in Ve, Fb, Vt/Ti and Vt/Te in relation to increases in pedal frequency were additive. However, when these two lower WLs were compared to the H-WL, the interaction between pedal frequency and Ve, Fb, Vt/Ti and Vt/Te was multiplicative. In addition, the interaction between WL and RPM on Vt and Ti was additive when comparing the M-WL and H-WL and multiplicative when these two lower WLs were compared to the H-WL. Correlation analysis indicated that for all WLs, Te was more highly related to Fb than was Ti, while Vt/Te was more highly related to Ve than was Vt/Ti. Our findings suggest that during M-WL and H-WL, increases in Ve are accomplished by progressive increases in Fb and decreases in Te, while during L-WL, increases in Ve are achieved by progressive increases in both Fb and Vt.

Male Fischer rats (n=43) were used in a diet-diet/ exercise design to investigate the apparent protein sparing effects of exercise. The animals were divided into five groups: INITIAL (baseline), SEDENTARY (control), DIET, DIET/EXERCISE, and EXERCISE. Carcasses were analyzed for body composition, the blood for plasma alanine concentration and the urine for urea nitrogen concentration. The results showed no significant differences between groups in urinary urea nitrogen, plasma alanine, body weight, or carcass weights. The EXERCISE group had a significant increase in percent protein and a significant decrease in percent fat and grams of fat when compared to all other groups (p <.05).

Lameness is the most common medical complaint amongst domestic horses. Consequently, lameness assessment skills are expected of veterinary graduates as a day one skill by the Royal College of Veterinary Surgeons. However, recognising lameness is inherently difficult, especially for mild cases: even experienced assessors regularly disagree on the affected limb. The impact of a resulting misdiagnosis can be profound for both horse and owner. Even today, the biomechanical changes associated with lameness and the mechanisms of subjective clinical decision making are far from understood. Not surprisingly, there is currently no standardised way to teach students the 'art' of lameness detection. Hence, this thesis investigated core elements of the lameness examination in the framework of task analysis, combining biomechanics, vision science and educational research. Mechanical principles of movement asymmetry adaptations associated with locomotion of sound and lame horses on the straight, circle and after flexion tests were investigated. Subjective perception and objective quantification of asymmetry were compared, ranging from detection thresholds of naIve observers to factors influencing experienced veterinarians. Student performance at different stages was evaluated to understand the foundations students bring to future training. Expert visual approaches to lameness detection were quantified by means of eyetracking, investigating whether general principles can be derived to guide teaching. This work showed that it is possible to model and consequently simplify movement adaptations during lameness for future computer based training tools, however a systematic asymmetry bias of sound horses during lunging and after limb flexion needs to be considered. Differences between visual perception and objective quantification of asymmetry highlight the need for further exploration of perception-based diagnostics. While experts used relatively similar approaches when examining horses on the straight, there were considerable differences during assessment on the circle; in future, it would be of benefit to. develop a reliable and uniform assessment strategy.

by Tong Kwok-keung. / Year shown on spine: 1997 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (p. [99]-[104]) / Acknowledgements --- p.i / Abstract --- p.ii / List of Tables --- p.vii / List of Figures --- p.viii / List of Abbreviations --- p.ix / Introduction --- p.1 / Background of Study --- p.1 / Statement of the Problem --- p.3 / Significance of Study --- p.7 / Review of Literature --- p.9 / Ventilatory Muscle Capacity - a Limiting Factor of Exercise Performance --- p.9 / Rib Cage Loading as a Respiratory load --- p.11 / Methods of Rib Cage Loading --- p.13 / The Physical Changes in Respiratory System during Rib Cage Loading --- p.14 / The Physiological Changes in Cardiorespiratory System during Rib Cage Loading --- p.17 / Mechanisms for the Changes in Ventilatory Muscle Activity andin Respiratory Response during Rib Cage Loading --- p.20 / Effects of Rib Cage Loading on Exercise Performance --- p.23 / Summary of Review --- p.25 / Methodology --- p.28 / Statement of Hypotheses --- p.28 / Operational Definitions of Variables --- p.28 / Subjects --- p.31 / Procedures --- p.31 / Instrumentation --- p.33 / Methods of Measurement --- p.36 / Assumptions --- p.50 / Data Analysis --- p.51 / Results --- p.53 / "Physical Characteristics, Forced Spirometry and Maximal Aerobic Power of Subjects" --- p.53 / Effects of Rib Cage Compression on Subdivisions of Lung Volume and Total Respiratory Elastance --- p.53 / Effects of Rib Cage Compression on Exercise Endurance --- p.56 / Effects of Rib Cage Compression on Ventilatory Muscle Function during the cycle exercise --- p.60 / Effects of Rib Cage Compression on Respiratory Response at Rest and during Exercise --- p.63 / Effects of Rib Cage Compression on Oxygen Consumption and Gas Exchange at Rest and during Exercise --- p.69 / Effects of Rib Cage Compression on Heart Rate and Arterial Blood Pressure at Rest and during Exercise --- p.73 / Discussion --- p.79 / The Physical Changes in Respiratory System during Rib Cage Compression --- p.79 / Reduction in Cycle Exercise Endurance with Rib Cage Compression --- p.81 / Conclusion --- p.94 / Implications --- p.95 / Delimitations and Limitations --- p.96 / Suggestions --- p.97 / Bibliography / Appendix I Informed Consent / Appendix II Cycling Protocol for Incremental Exercise Test / Appendix III Cycling Protocol for Cycle Exercise Endurance Test / Appendix IV / Figure IV-I. The changes in volume-pressure tracings with and without rib cage compression during measurement of total respiratory elastance / Table IV-I. The subdivisions of lung volume of each subject with and without rib cage compression / Table IV-II. The cycle exercise duration of each subject with and without rib cage compression / Table IV-III. The static maximum inspiratory and expiratory pressures of each subject before and after exercise during both cycle exercise tests / Table IV-IV. & IV-V. The means of each parameter of respiratory response during both cycle exercise tests / "Table IV-VI. The means of end-tidal C02 tension, arterial oxygen content and oxygen consumption during both cycle exercise tests" / "Table IV-VII. The means of heart rate, and systolic and diastolic blood pressures during both cycle exercise tests"

Yu, Jie. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese; appendixes includes Chinese.

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