Thesis (M.A.)--Western Kentucky University, 2008. / Includes bibliographical references (leaves 45-50).

Pregnancy is an unique period in a woman’s life in which her body undergoes rapid and drastic changes. Historically, physical activity was thought to be dangerous during pregnancy and women were recommended to avoid engaging in most physical activities. Mechanical efficiency, the ratio of external work and energy required to perform a task, is an important consideration when addressing the safety of physical activity, but also when defining recommendations to this population. Currently, there is limited literature that characterizes the change in mechanical efficiency across pregnancy. Of the available literature, suboptimal methodologies were employed, resulting in conclusions that conflict with what would be expected. The purpose of this thesis was to characterize mechanical efficiency across gestation and to compare with non-pregnant women. Women performed a standardized treadmill task in early, mid, and late pregnancy, and energy dynamics were measured. Results showed that energy requirements and external work performed increased over time, and that these were in relation to gestational weight gain. Pregnant women did not exhibit a change in the efficiency of performing a walking task. Overall, these results add to the current literature that supports women’s engagement in physical activity during pregnancy.

We compared sense of movement and position in unconstrained 3-dimensional tasks in younger and older adults to investigate whether older adults have diminished kinesthetic sense. Active and passive kinesthesia were compared in a novel dynamic-position sense task and also in a static-position sense task. Older (65-85 years) and younger (18-22) adults performed tasks in which they moved the right arm to touch the right index tip to the moving and stationary left index (target) fingertip in different conditions. In the dynamic task the participant or experimenter moved the left upper limb and, after a variable delay, the subject moved the right arm to attempt to touch the right index-tip to the moving target index-tip. Participants performed the dynamic task with vision actively moving both limbs (VDA), without vision while actively moving both limbs (NVDA), and without vision with the experimenter moving the target limb (NVDP). In the static task the participant (NVSA) or experimenter (NVSP) moved the target limb to a position and held it stationary while the participant moved the right arm to attempt to touch the right index tip to the target fingertip. Both younger and older adults performed the dynamic task remarkably accurately with errors averaging less than 1.6 cm across the 3 conditions. Mean 3-dimensional distance errors averaged slightly (0.19 cm) larger in older adults in the dynamic task (F₁,₂₅=5.88, p=0.02). Variable distance errors did not differ between age groups in the dynamic task (F₁,₂₅=0.90, p=0.35). Small errors were observed in all conditions. NVDP had the largest mean distance errors (1.81 cm) of moving conditions, followed by NVDA (1.65 cm), and VDA had the smallest errors (1.27 cm) (F₂,₅₀=49.55, pcorr< .001, all post hoc tests less than p< 0.05). There was no evidence of errors depending on target index-tip peak speed or location. Interestingly, distance errors in the static tasks averaged 3.0 cm and were clearly larger than in the dynamic tasks (F₁,₂₅=57.78, p< 0.001). Within the two static conditions, average errors were 0.5 cm larger in the NVSP condition than in the NVSA condition (F₁,₂₅=7.56, p=0.01). Average distance errors trended to being larger in older adults in static conditions (F₁,₂₅=3.53, p=0.07). Variable distance errors were similar for the two age groups in the static conditions (F₁,₂₅=.25, p=0.35), averaging 1.77 cm in NVSP and 1.38 cm in NVSA (F₁,₂₅=.7.98, p< 0.01). These results suggest that regardless of age, availability of visual information, active/passive target limb movement, or reaching to static versus moving targets that adults are generally quite accurate at localizing fingertip position. The finding that accuracy in the static and dynamic tasks when vision was not allowed was only slightly better when the subjects actively moved the target arm (i.e., NVDA, NVSA) than when the target arm was moved by the experimenter (NVDP, NVSP) indicates that internal models may contribute only very slightly to proprioceptive localization of the upper limb. However, it is clear that kinesthetic sensory information from the periphery is sufficient to allow the central nervous system to accurately calculate position of the endpoint of the limb (tip of the index) while unconstrained in 3-dimensional space.

Several factors may determine the rate. at which exogenous carbohydrate (CHO) is utilised by the human working muscles during prolonged (> 90 min moderate-intensity (63% of peak sustained power output [PPO]) exercise. These include i) the rate of gastric emptying of an ingested fluid, ii) the rate of digestion, absorption and subsequent transport of glucose into the systemic circulation, and iii) the rate of glucose uptake and oxidation by the working muscles. To test the hypothesis that the rate of gastric emptying is the primary factor limiting the rate of CHO delivery to the working muscles during exercise, uniformly labelled ¹⁴carbon (U-¹⁴C) tracer techniques were used in association with conventional gas exchange measurements and post-exercise gastric aspiration to compare the rates of gastric emptying, intestinal CHO delivery and ingested CHO oxidation from 15 g/100 ml solutions of glucose, maltose, a 22 chain-length glucose polymer, and an isocaloric 'soluble' starch preparation. Two groups of six highly-trained male cyclists or triathletes each ingested two of the test drinks which were given as a 400 ml loading bolus immediately before and then as eight 100 ml feedings at 10 min intervals during 90 min of continuous cycling at a work rate of 63% of PPO (~70% of maximal oxygen consumption [VO₂ₘₐₓ]).

Intracellular acidosis is a putative agent of skeletal muscle fatigue, in part, because acidosis depresses the calcium (Ca2+) sensitivity and force production of muscle (18, 50). However, the molecular mechanisms behind this depression in Ca2+ sensitivity and force production are unknown. This gap in knowledge poses a significant challenge in generating a complete understanding of the fatigue process. To close this gap, the ability of myosin to bind to a single actin filament was measured under acidic conditions, in a laser trap assay, with and without regulatory proteins. Decreasing pH from 7.4 to 6.5 reduced the frequency of single actomyosin binding events at submaximal (pCa 8 – pCa 6), but not at maximal (pCa 5 - 4) concentrations. To delineate whether this was due to a direct effect on myosin versus an indirect effect on the regulatory proteins, troponin (Tn) and tropomyosin (Tm), binding frequency was also quantified in the absence of Tn and Tm. Acidosis did not alter the frequency of actomyosin binding events in the absence of regulatory proteins (1.4 ± 0.05 vs 1.4 ± 0.13 events/sec for pH 7.4 and 6.5). Additionally, acidosis did not significantly affect the size of myosin’s powerstroke, or the duration of binding events in the presence of regulatory proteins, at every pCa. These data suggest that acidosis impedes activation of the thin filament by competitively inhibiting Ca2+ binding to TnC. This slows the rate at which myosin initially attaches to actin, therefore less cross-bridges will be bound and generating force at any given sub-maximal pCa.

Skeletal muscle satellite cells (SC) are essential in muscle repair and regeneration. The role of SCs in mediating hypertrophic adaptations following resistance training has been widely studied. Recent evidence from endurance training studies suggest that SCs may also play a role in mediating non-hypertrophic adaptations. Indeed, it has been shown that satellite cells respond to endurance training. Work in rodent models suggest that exercise intensity may play an important role in expanding the SC pool whereas the results of endurance training studies in humans are much less consistent. Limited evidence also suggest that exercise intensity may be important in mediating exercised-induced capillarization following endurance training in humans. In both instances, it is unknown whether the on-and-off pattern characteristic of interval training (i.e. the rest-work cycles) plays a role in the magnitude of these skeletal muscle responses to this type of exercise. Thus, we sought to determine if the rest-to-work cycle plays a role in the scope of these skeletal muscle responses by comparing the SC response and capillarization to two distinct work-matched protocols that are performed at the same intensity but at two different exercise patterns (interval versus continuous). We hypothesized that interval exercise will elicit a greater SC response and induce greater capillary growth compared to work-matched continuous exercise. Ten young active individuals performed 12 sessions of counterweighted single-leg cycling over 4 weeks. Each leg was randomly assigned to Interval (INT) (10 x 3-min intervals at 50% of single leg peak power output (PPO), with 1 min recovery) or Continuous (CONTIN) (30 min at 50% PPO, followed by 10 min recovery), which were performed 5 min apart on each day, in an alternating order. Resting muscle biopsies were obtained from the vastus lateralis pre- and post-training. Immunofluorescent microscopy of muscle cross sections was used to assess muscle fibre capillarization, SC expansion and activation. Western blot analysis was performed on pro-angiogenic factors, specifically VEGF and VEGFR2. Mixed muscle SC activation increased in the INT leg compared to the pre-training time-point (3.2 ± 0.5 vs. 1.5 ± 0.2 Pax7+/MyoD+ cells/ 100 myofibers, respectively; P < 0.05). Mixed muscle SC activation did not increase significantly in the CONTIN leg compared to the pre-training time-point and there was no significant difference in activation between CONTIN and INT post-training. With regards to capillarization, no differences in type I or type II muscle fibre CC (capillary contacts), C/Fi (individual capillary-to-fibre ratio) or CFPE (capillary-to-fibre perimeter exchange index) were observed post-training or between legs. No significant expansion of the SC pool occurred in either legs post-training and no increases in fibre cross-sectional area was observed. This study presents novel evidence of mixed muscle SC activation following interval exercise training that is not observed following work- and intensity-matched continuous exercise training. This suggest that the rest-to-work cycle associated with interval exercise may dictate, to some extent, SC activation whereas it may not be a primary stimulus for training-induced changes in capillarization. / Thesis / Master of Science (MSc)

<div>As the soft tissue that transmits muscular forces to the bony skeleton, tendons play a key role in the human musculoskeletal system and must adapt over time to repeated mechanical loads to maintain functionality. Resistance exercise is one of the primary stimuli for increases in tendon size and strength in healthy, young individuals, but similar benefits are not observed in healthy, aged tendon. This failure in the elderly to adapt, along with the fact that tendons inevitably decline in morphology and function with age, puts older individuals at an increased risk of poor tendon health, subsequent injury, and a compromised quality of life. Alternative strategies to preserve and strengthen aged tendon has gone largely unexplored, highlighting a critical need to determine an effective stimulus for tendon adaptations in aging populations</div><div>The purpose of this study was to determine if age impacts the delivery of orally-consumed amino acids (AA) to the peritendinous Achilles space. If so, this investigation could serve as the foundation for future studies to evaluate the efficacy of supplemental amino acids for inducing positive adaptations in tendon during exercise. Furthermore, an enzyme-linked immunosorbent assay (ELISA) was performed to quantitively measure procollagen, a precursor of collagen, in the samples to evaluate the impact on supplemental amino acids on collagen synthesis. </div><div>To assess amino acid delivery, a microdialysis fiber was inserted into the peritendinous space anterior to the Achilles tendon in healthy young (n = 7, 21-30 years) and elderly (n = 6, 60-75 years) men and women after a twelve-hour fast. After baseline collection, subjects consumed a non-caloric, noncaffeinated AA beverage (16.65 g). Microdialysis samples were collected every fifteen minutes for four hours and analyzed using reverse-phase high-performance liquid chromatography. </div><div>Amino acid delivery to the peritendinous space was not compromised with age, and the administration of amino acids upregulated procollagen synthesis significantly more in healthy, elderly subjects than in those that are healthy and young. Though preliminary, these findings provide a strong foundation for future studies assessing the impact of amino acid supplementation as novel impetus for tendon adaptations in the elderly. </div><div><br></div>

<p>This thesis investigated the acute and chronic responses of human skeletal muscle to high-intensity exercise, with a particular focus on markers of mitochondrial content, and the potential for nutrition to manipulate the adaptive response in recreationally active individuals. The acute response was primarily assessed via measurement of signalling proteins and mRNA species linked to exercise-induced mitochondrial biogenesis. The chronic response was determined via changes in the protein content or maximal activities of mitochondrial enzymes after training. Study 1 examined whether the manner in which a given amount of high-intensity cycling work was performed (i.e., in an intermittent or continuous fashion) altered the acute metabolic response to exercise, and whether the acute response was indicative of longer-term adaptations. Despite the similar acute activation of signalling proteins after the intermittent and continuous matched-work exercise protocols, 6 wk of training with the continuous protocol did not increase mitochondrial content, contrary to what we have previously shown after 6 wk training with the intermittent protocol. This suggests that the intermittent application of a low-volume, high-intensity stimulus is important to elicit training-induced increases in mitochondrial content. Furthermore, Study 1 showed that acute changes in specific signalling proteins did not necessarily predict chronic adaptations. Studies 2 and 3 examined whether specific nutritional interventions, previously shown to modulate acute exercise capacity or metabolic response, altered the mitochondrial adaptive response to several weeks of HIT. Neither manipulating carbohydrate availability between twice daily training sessions, or chronic ingestion of β-alanine, augmented skeletal muscle adaptations in response to 2-6 wk of HIT. It is possible that small influences of nutrition were overwhelmed by the potency of HIT, which stimulated marked increases in mitochondrial content in this population. Overall this thesis advances our basic understanding of the skeletal muscle adaptive response to HIT and the influence of nutrition.</p> / Doctor of Philosophy (PhD)

Orientador: Luiz Claudio Nogueira Mendes / Coorientador: Lina Maria Wehrle Gomide / Banca: Flavia de Almeida Lucas / Banca: Rafael Resende Faleiros / Resumo: O objetivo do trabalho foi avaliar a influência de diferentes frequências de treinamento sobre o condicionamento físico de equinos através da avaliação das concentrações de lactato plasmático, das concentrações séricas de CK, AST e LDH e dos parâmetros físicos vitais e hematológicos, após exercício físico de alta intensidade e curta duração. Amostras de sangue venoso foram obtidas de 16 equinos da raça Quarto de Milha, que foram divididos em dois grupos: grupo de treinamento regular (GTR) e grupo de treinamento esporádico (GTE), em sete diferentes momentos: 30 minutos antes do exercício (MA), imediatamente após (MD), 30 minutos (M0,5), uma (M1), duas (M2), seis (M6) e 24 (M24) horas após a prova de três tambores. Não foram observadas diferenças entre os grupos. Frente a esse resultado os equinos foram rearranjados em um grupo único, para a avaliação do condicionamento físico desses animais de uma forma geral. Além disso, foram realizados testes de correlação dessas variáveis para melhor observação do comportamento entre elas. Como resultado, houve um aumento significativo no MD das variáveis: lactato, FC, FR, He, VG, Hb e LINF, no entanto todas as variáveis voltaram aos seus valores basais antes de 24 horas após o exercício, indicando que os equinos avaliados possuem condicionamento físico satisfatório. Quanto às correlações, foram encontrados coeficientes de correlação forte e positivo entre as variáveis: He, VG eHb, e entre LEU e GRAN, em todos os momentos, entre LDH e AST ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the influence of different frequencies of training on the fitness of horses through the evaluation of plasma lactate, serum concentrations of CK, AST and LDH and clinical and hematological parameters after high intensity and short durationexercise. Venous blood samples were obtained from 16 horses of Quarter Horses, which were divided into two groups: regular training group (GTR) and sporadic training group (GTE) in seven different times: 30 minutes before exercise (MA), immediately after (MD), 30 minutes (M0,5), one (M1), two (M2), six (M6) and 24 (M24) hours after barrel racing. No differences were observed between the groups. In view of this result the horses were rearranged into a single group, to evaluate the fitness of these animals in general. In addition, correlation tests were conducted to observe the interdependence of these variables after exercise. As a result, there was a significant increase in MD of the variables lactate, HR, FR, He, VG, Hb and LINF, however all variables returned to their baseline values within 24 hours after exercise, indicating that the assessed horses have satisfactory physical condition. As for the correlations, strong and positive correlations were found between the variables: He, VG and Hb and between LEUC and GRAN, at all times, between LDH and AST in the M6, AST and CK in M0 and HR and RR in M24. It was concluded that the training frequency did not influence the fitness of the animals, however they... (Complete abstract click electronic access below) / Mestre

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"