Arterial desaturation in fit athletes, during exercise at an intensity greater than or equal to 90% of VO₂ max has been reported by a number of authors yet the etiology of these changes remain obscure. Inadequate pulmonary ventilation due to a blunted respiratory drive, or lung mechanics has been implicated as a factor in the etiology of this phenomenon. It was the purpose of this experiment to investigate the relationship between arterial desaturation and ventilatory response to hypoxia (HVR). Twelve healthy male subjects ( age = 23.8 ± 3.6 yrs., height = 181.6 ±₋₁ 5.6 cms., Weight = 73.7 ± 6.2 kg., VO₂ max = 63.2 ± 2.2 ml .kg . -1 2 .min⁻¹) performed a five minute exercise test on a treadmill at 100% of VO₂ max. Arterial samples for pH, PCO₂, PO₂, and SaO₂ were withdrawn via an indwelling arterial cannula at rest and every 15s throughout the exercise test. The blood gas samples were analyzed with an Instrument Laboratories 1306 blood gas analyzer. Ventilation and VO₂ were measured by a Beckman metabolic measurement cart. On a separate occasion the ventilatory response to hypoxia (HVR) was determined by recording VE as progressive hypoxia was induced by adding N₂ to a mixing chamber. SaO₂ was measured using a Hewlett-Packard ear oximeter; to maintain isocapnia small ammounts of CO₂ were added to the open circuit system. ANOVA for repeated measured was used to evaluate changes in blood gases, ventilation, and VO₂. Simple linear regression and multiple linear regression was used to evaluate the relationship between the changes in SaO₂ and HVR and the descriptive variables. Subjects showed a significant decline in arterial saturation and PO₂ over the course of the test (p < 0.01,and p < 0.01). Four subjects (Mild) exhibited modest decreases in SaO₂ to (94.6 ± 1.9%), three (Moderate) showed an intermediate response (SaO₂ 91.6 ± 0.1%) and five (Marked) demonstrated a marked decrease in arterial saturation (SaO₂ = 90.0 + 1.2%). The differences in PO₂ and SaO₂ between Mild and Marked groups were significant ( p < 0.05, and p < 0.01); there were no significant differences between groups in VE, VO₂, pH or PCO . There was no significant correlation between the lowest SaO₂ reached and HVR, or any of the descriptive variables. Nine subjects did not reach maximal VE (as determined by the VO₂ max test) on the exercise test, two subjects 2 exhibited similar ventilation, and the remaining subject exceeded maximal VE, but fell into the Mild group with respect to desaturation. Oxygen uptake exceeded that recorded for the VO₂ max determination for four of the five subjects in the Marked group; the remaining subjects demonstrated lower or similar values. It was concluded that arterial desaturation was not related to blunted hypoxic drive. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Nine male Physical Education students were selected to test the hypothesis that addition of CO₂ to the inspired air during recovery will cause significant increases in ventilation above control conditions and that recovery from submaximal exercise will be enhanced by the addition of 2.78% or 5.80% CO₂ to room air. The exercise was administered for six minutes at a workload predetermined to elicit 75% of his maximal oxygen uptake. The dependent variables (heart rate, ventilation, oxygen uptake, and carbon dioxide elimination) were subjected to a one way analysis of variance and significant F ratios evaluated using Dunnett's Test. Ventilation is increased significantly (p<.05) above control values with the addition of 5.80% CO₂ to room air during recovery however, there is no significant increase in oxygen uptake. The addition of 2.78% CO₂ to room air during recovery does not significantly (p>.05) increase ventilation; there is however a significant (p<.05) increase in oxygen uptake in the first 30 seconds of recovery. Neither treatment effect causes significant changes in heart rate. The addition of 5.80% CO₂ to the inspired air significantly (p<.05) reduces carbon dioxide elimination. In 4 subjects, the effect produced a carbon dioxide uptake at certain time intervals. The addition of 2.78% CO₂ to the inspired air caused a significant (p<.05) reduction of carbon dioxide elimination in the first minute of recovery. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

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Six males of similar body composition and aerobic physical fitness were tested to determine their perceptual responses to exercise and the relation of these perceptions to core temperature (Tᵣₑ) under three conditions of thermoregulatory stress. The experimental protocol consisted of 120 min of upright stationary cycling at 50% VO₂ max under conditions of neutral (24°C, 50% RH/hydration (NH), hot (35°C, 50% RH/hydration (HH), and hot (35°, 50% RH/hypohydration (HP). Perceptual responses were determined by Borg's 10-point category ratio scale ( 1980) and by a multi-dimensional symptom scale which contained six symptoms commonly thirst; associated with heat stress: irritability; headache; and weakness; fatigue; dizziness. Core temperature responses and perceptions were obtained throughout exercise in each condition. An analysis of variance was utilized to determine if significant differences existed between Tᵣₑ responses, symptom scale responses and RPE responses in each condition. Analysis of variance revealed statistically significant (P < 0.05) differences between Tᵣₑ responses in the three conditions. Statistically significant (P < 0. 05) differences were also found for the symptom scale responses of thirst and weakness. Regression analysis within each condition was utilized to evaluate the relationship of Tᵣₑ and RPE responses and of Tᵣₑ and the combined scores of weakness, fatigue and thirst. The regression analysis revealed an R² or . 997 for prediction of Tᵣₑ using RPE data in the HP trial; the R² for Tᵣₑ prediction from the symptom scale responses in HP was 0.992. The R² values for prediction of Tᵣₑ in the NH and HH conditions were .953 and .983, respectively. The R² obtained in the HH and NH conditions were lower than those R² obtained in the HP trials for both the RPE and symptom scale predictors. These data suggest that RPE is a meaningful predictor of Tᵣₑ increases i.e., given a particular RPE, the model gives a meaningful estimate of Tᵣₑ within the range of core temperatures that were observed. / Master of Science

Previous investigations have shown that metabolic rate remains elevated for a period of time after the cessation of exercise. While other investigations have examined the effect of intensity and duration of prior exercise, the purpose of this study was to examine the effect of exercise mode and the employment of different muscle masses on the elevation of post-exercise metabolic rate (EPOC). Fifteen non-smoking, physically active females (21.1 ± 1.3 years; 21.4 ± 4.6 %BF) volunteered for this investigation. Each subject completed a graded maximal exercise test (GXT) on the Monark 880 cycle ergometer (Max HR=192.5 ± 2.3 bpm; Max V02=2.68 ± O.lll/min; Max RPE=19.5 ± 0.1) from which a heart rate corresponding to 70% V02max was chosen. Subjects then exercised on either a Monark 880 cycle ergometer (LE) or the Schwinn Airdyne (ALE) in random order for thirty minutes at the prescribed heart rate (HR). Exercise bouts were separated from each other and from the GXT by at least 48 hours. Workloads were monitored in five minute intervals and adjusted to maintain the appropriate heart rate. The mean exercise heart rates were 172.5 ± 2.8 bpm for the LE bout and 170.0 ± 2.8 bpm for the ALE bout, respectively. Two-way repeated measures ANOVA revealed no significant difference \r >0.05) between exercise treatments in terms of HR or V02. Repeated measures trend analYSis revealed no significant difference in either EPOC or post-exercise heart rate between the two treatments across a one-hour seated recovery period. There was also no significant difference (p>O.05) in excess post-exercise caloric expenditure during the recovery period as a result of the different exercise treatments. Therefore, this suggests that neither exercise modality nor the distribution of work over a larger muscle mass had an effect on EPOC when exercise intensity and duration were held constant. / Master of Science

The main purpose of this study was to investigate the relationship between human growth hormone (hGH) and two separate components of resistance exercise. Eight non-weight-trained subjects (23.33 ± 0.3 yrs) performed three force production trials (FPT), at different concentric workloads, and an 120% eccentric exercise trial (EET) on the Cybex 6000. Blood samples (3 mls) were taken pre- and post-exercise and analyzed for lactate, creatine kinase (CK) and hGH. Electromyographic (EMG) activity of the quadriceps muscle was recorded during each trial. The mean peak torque produced during the FPTs increased as work intensity increased but was the highest in the EET. The data for total work showed a proportional relationship with the intensity of the three concentric work loads but not the 120% EET. EMG activity of vastus medialis (VM) and rectus femoris (RF) measured during EET was 26% less than RF of 50% and 15% less than VL of 70% in FPT, respectively. The highest hormonal response occurred following the 120% EET. The hormonal response following the FPTs was highest in the 90% FPT with the two lower work intensity trials (50 and 70%) showing no clear hormonal response. Although the hGH response was the highest in the 120% EET, the post-exercise lactic acid levels in EET were 24% less than that of the 90% FPT. Creatine kinase (CK) activity was significantly elevated 36 hours after the last bout of EET which suggests that the eccentric exercise resulted in muscle damage. The results from concentric trials showed that muscle force generation, EMG, and lactic acid of the three different concentric trials were well correlated to the pattern of hGH secretion. However, only peak torque was consistent with the hGH response of the EET. The highest peak torque and hGH levels were achieved with eccentric exercise. The highest levels of fatigue, as a result of the combination of longer exercise time and overloading of the muscle during EET, may explain the higher hGH output. The muscle damage caused by the eccentric trial was enough to induce delayed onset of muscle soreness and may be the stimulus for the higher hGH output. The hGH response may facilitate repair of the muscular damage induced by eccentric exercise by promoting protein synthesis. / School of Physical Education

Call number: LD2668 .T4 1979 S64 / Master of Science