This study aimed to investigate the response of trained intercollegiate and national level female athletes to twelve week depth-jump (DJ) training performed twice weekly with forty repetitions of DJs performed each training session. Results of statistical analysis revealed that only the .3 and .5 meter experimental group improved significantly on VJ ability. However, there was no significant increase in LS for either experimental group compared to the control group. It was concluded that DJ training from .3 and .5 meter heights is more optimal for increasing VJ ability of trained female athletes compared to the 0.75 and 1.1 meter heights as recommended by Verhoshanski for trained male athletes. It was also concluded that DJ training has the the ultimate purpose of developing explosive leg power not leg strength.

In man the metabolic heat produced during physical exercise stresses the thermoregulatory system, particularly if hot, humid environmental conditions prevail. It has recently been postulated that endogenous opioids may play a role in regulating body temperature at rest and because it has also been shown that blood levels of these substances increase during exercise, the possibility exists that endogenous opioids may play a role in thermoregulation during exercise. A study was conducted in two parts to determine the thermoregulatory response during exercise with and without pharmacologic blockade of the opioid receptor. In Part I nine healthy male subjects performed 30 minutes cycling at 50 % maximal aerobic capacity in an environmentally controlled laboratory. The subjects received either placebo, 2mg or 10mg naloxone hydrochloride in a randomized double-blind crossover fashion prior to the exercise test. Rectal temperatures were recorded at one-minute intervals and cardiorespiratory parameters were measured during the test. Water loss was calculated from differences in nude body weight. In part II eight male subjects performed a graded maximal cycle ergometer test after receiving either placebo or 2mg naloxone in a randomized double-blind crossover fashion. Rectal and sublingual temperatures were recorded before and after the test and oesophageal temperature was recorded at one-minute intervals during the test. Cardiorespiratory parameters were recorded during the test. The results of Part I show that rises in rectal temperature as well as calculated water losses were similar for placebo and after the administration of both 2mg and 10mg naloxone. Similarly, during maximal exercise (Part II) the rise in rectal and oesophageal temperatures was equivalent for placebo and 2mg naloxone but sublingual temperature failed to rise during exercise following the 2mg naloxone dose. Cardiorespiratory responses did not differ between placebo and naloxone tests in both Part I and Part II of the study. These results indicate that naloxone-mediated blockade of opioid receptors does not affect rectal and oesophageal temperature responses to either submaximal or maximal exercise. Naloxone appears to selectively alter the sublingual temperature response to exercise possibly by altering local blood flow. It is concluded that insofar as naloxone induced opioid receptor blockade provides a measure of the function of the endogenous opioid system, this study suggests that the endogenous opioid system does not play a significant role in thermoregulation during exercise.

This study examined the effects of steady, graded, and no exercise on stress reduction, and the effects of self-confidence on stress reduction through exercise. Seventy-two male and female volunteers from the Portland area, ranging in age from 19-49 years, served as subjects. Subjects completed pre and post measures of the Tennessee Self-Concept Scale and the state portion of the Spielberger State-Trait Anxiety Inventory. Subjects were divided into two experimental and one control group matched according to age and exercise history. The control group kept its exercise at a minimum for eight weeks. Exercise programs for the two experimental groups consisted of twelve minute work bouts on ergometers three times per week, for eight weeks. Work bouts were at a seventy percent maximum heart rate. Due to attrition and a random drop of subjects in the control group, thirty-one subjects remained. Analyses found a significant stress reduction for the steady exercise group (t = -2.81,p = .017), but not for the graded or no exercise group. Stress reduction was negatively correlated with self-confidence, though not significantly, and no significant differences were found between the self-confidence scores. A significant correlation was found between pre-stress scores and preself- conf idence scores (r = -.306,p = .04).

The energy cost of performing 1 and 3 sets of strength-type (6-8 RM) and endurance-type (30-35 RM) bench press exercise was estimated by indirect calorimetry in 10 male college students. The total net energy cost of performing 3 sets of endurance-type resistive exercise (20.57 ± 1.86 kcal) was significantly (p-1) the strength-type exercise (2.35 ± 0.19) resulted in a significantly (p

The purpose of this dissertation series was to examine oxygen uptake kinetics in skeletal muscle by evaluating responses of local muscle deoxygenation during incremental exercise in healthy individuals using near-infrared spectroscopy (NIRS). Metabolic activity in skeletal muscle, as part of the integrative responses of the cardiovascular, respiratory and neuromuscular systems, are major determinants of an individual’s physical capacity and function. The workings of these systems, called whole-body metabolism, affect the capability of an individual to engage in activities of daily living, to exercise, and participate in athletic performance. Thus, they have a strong impact on health as engagement in physical activity is well known to be effective in improving cardiorespiratory fitness and reducing the risks of chronic disease. At this time, the in vivo relationships between whole-body metabolism and local muscle metabolic activity are not well understood, but with the availability of NIRS technology this is possible. NIRS is a noninvasive optical technique used to continuously measure changes in muscle tissue oxygen saturation locally, allowing interrogation of the functional integration between muscle metabolism and the cardiovascular system in intact human beings, which is what the series of studies in this dissertation evaluate. Healthy adults and adolescents were enrolled as healthy control participants into an observational study evaluating changes in local muscle oxygen uptake in neuromuscular disease during exercise. Participants performed a maximal cardiopulmonary exercise test (CPET) on a recumbent cycle ergometer. Changes in muscle deoxygenation (HHb), reflecting local oxygen uptake, were measured using NIRS and whole-body metabolism was assessed synchronously via expired gas analysis. After an initial increase in HHb at exercise onset, a consistent pattern of plateau in HHb was observed in the healthy participants near the end of peak exercise. Despite increasing workload and oxygen uptake (VO2) in the final minutes of the test, it was unclear what mechanisms were contributing to this HHb response. It was hypothesized that the HHb-Workload relationship evaluated at the time of VO2peak would be non-linear, such that a greater maximum workload achieved at VO2peak would not be linearly matched by greater ΔHHb (i.e., greater total change from rest to VO2peak). First, a critical evaluation of the literature was conducted to explore this hypothesis. Chapter 2 provides the results of a scoping review that was performed in order to better understand the scientific evidence using NIRS that describes the relationships between indices of muscle oxygen saturation and workload during incremental exercise. This formed the basis to pursue the hypothesis-driven research presented in the subsequent chapters, interrogating the overarching question of this dissertation related to the HHb-Workload relationship. The review revealed there are three methodological approaches to examining changes in muscle oxygen saturation and workload, the least common of which was examination of HHb and workload at the VO2peak time point. Changes in muscle oxygen saturation and work have also been studied as the change in muscle oxygenation over the duration of exercise and at a certain time point or intensity during incremental exercise. Based on the literature, it was clear that there was a dearth of research examining the HHb plateau response in relation to work at VO2peak. Accordingly, chapter 3 provides the results of a pilot study that evaluated the relationship between change in HHb (ΔHHb) and the maximum workload (MW) achieved at VO2peak, where it was hypothesized that the relationship at this time point would be non-linear. A polynomial regression model was used to describe the relationship. The results of this study showed that at lower maximum workloads there were initial increases in ΔHHb with increasing maximum workload but at the highest maximum workloads, ΔHHb attenuated. A polynomial model including ΔHHb and MW, with VO2peak (an indicator of cardiorespiratory fitness) as a covariate, best characterized the relationship. Age was not significantly related to ΔHHb or MW, and VO2peak appeared to play a partial role as its inclusion as a covariate helped explain approximately a quarter of the variance, suggesting other factors may be contributing to the attenuated HHb response. From this pilot work it was hypothesized that the attenuation in ΔHHb at higher maximum workloads, and the HHb plateau observed during CPET, could be explained by muscle efficiency. If so, a longer duration and lesser slope of the HHb plateau in the minutes leading up to VO2peak occurs in muscles with higher metabolic efficiency. As muscle efficiency is defined as a ratio of external work accomplished to internal energy expended, the hypothesis, if true, would support a better matching of the internal work (VO2) to the external work (workload on the ergometer). Chapter 4 provides the results of a secondary analysis that sought to determine whether the observed plateau in HHb reflected muscular efficiency by comparing the slope of the HHb plateau (HHb[s]) to a commonly used method of assessing muscle efficiency, delta efficiency (DE). It was hypothesized that HHb[s] and DE would be inversely and significantly correlated, providing a potential mechanism for the attenuated HHb response and a noninvasive method for assessing muscle efficiency. In contrast to the hypothesis, HHb[s] and DE were not associated, suggesting that a mechanism other than muscle efficiency is contributing to the HHb plateau. Collectively, this series of studies demonstrate that there is a need to better understand the relationship between HHb and workload in healthy individuals, because of a paucity of evidence exploring the HHb-MW relationship at VO2peak, the finding that ΔHHb attenuates at higher maximum workloads, and that results suggest the HHb plateau phenomenon cannot be explained by muscle efficiency. Future work should seek to elucidate the mechanism that allows healthy individuals to achieve higher workloads (i.e., continue exercising at high intensity) without further increasing muscle oxygen uptake, in a larger more heterogeneous sample.

Athletes have continually sought to improve their physical performance. In order to accomplish this, athletes experiment with performance enhancing drugs, which are readily available to the athlete today. Cocaine, being one of them, is traditionally and popularly believed to increase muscular endurance and possess anti-fatiguing properties. The scientific literature as to whether cocaine is truly a performance enhancing drug is inconclusive. Moreover, few if any studies have been conducted on exercise performance following long term, repeated cocaine administration. The purpose of the present study was to determine the effects of 35 days of cocaine administration (25 mg/kg/day) on maximal endurance exercise capacity. Data were collected from six untrained male Sprague-Dawley rats. Resting and exercise heart rate and body temperature were recorded via radio telemetery. Running time to exhaustion was recorded via one weekly maximal treadmill exercise bout to exhaustion (26 m/min, at a 10% grade). Compared to saline controls, cocaine significantly decreased run time to exhaustion, following acute and chronic administration. Cocaine administration also significantly decreased maximal exercise heart rate. Chronic cocaine had minimal effects on resting heart rate and resting and exercise body temperature during maximal exercise conditions. These data indicate that daily, chronic cocaine administration significantly reduces endurance exercise capacity, and suggests that the decreased physical work capacity following cocaine is related to a decreased ability of the heart to function under maximal exercise conditions.

Skeletal muscle satellite cells are important for muscle repairing and muscle mass growth. For a successful muscle regenerative process, satellite cells have to sequentially undergoing different stages of myogenic process, i.e. proliferative state and differentiation state. To support this process, the presence of different circulating factors, such as immune cells, cytokines, and hormones, at the appropriate time course is critical. Among these factors, hormones, such as testosterone, cortisol, and IGF-1, have shown to play an important role in satellite cell proliferation and differentiation. Studies investigated the effect of testosterone on satellite cell using a supraphysiological dose in human or in cell culture demonstrated that testosterone is critical in satellite cell myogenic process. Due to the anabolic effect of testosterone on muscle, studies had been focused on the physiological means to increase the circulating testosterone concentration in the body to maximize the muscle mass growth from resistance exercise. The acute and transient increase in testosterone has shown to be beneficial to muscle mass growth and strength gain; however, this change in physiological testosterone concentration on satellite cell myogenesis is not known. Therefore the purpose of this dissertation is to first determine the effect of acute change in exercise-induced hormones on satellite cell myogenic state, then to determine if testosterone promotes satellite cell proliferation.

Acute aerobic exercise exerts a small beneficial effect on cognition. Much of the research to date has focused on cognitive changes following a bout of exercise, while little is currently known about changes in cognitive performance during exercise. The limited research that has been conducted suggests either positive, negative, or no effects on cognitive performance during exercise. Thus, the primary purpose of this study was to examine the effects of low-intensity cycling on cognitive function in college-aged students, indexed by response accuracy, reaction time, P3 amplitude, and P3 latency. Twenty-seven (Mage = 22.9 ± 3.0 years old) college-aged individuals were counterbalanced into low-intensity exercise (EX) and seated control (SC) conditions. During each condition, participants completed a 10-minute resting baseline period, 20 minutes of either sustained cycling or seated rest, and a 20-minute recovery period. Primary outcomes were assessed at 10-minute intervals (5 blocks total) throughout each condition via a modified oddball task. Across time blocks, both conditions exhibited faster reaction times on frequent trials but reduced accuracy to rare trials, suggesting a speed-accuracy tradeoff. There were no differences between conditions in P3 latency whereas a significant reduction in P3 amplitude was observed during the 20-minute exercise period compared to the control condition. Taken together, the results suggest that exercise at lower doses may have minimal influence on behavioral outcomes of cognitive performance but may impact more basic measures of brain function. Information gathered from this study may aid in the development of appropriate exercise prescriptions for populations looking to specifically target cognitive function deficits.

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