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No description available.

Six adult male volunteers of similar body composition and physical fitness were tested to determine plasma immunoreactive β-endorphin (Piβ-EN) response under three conditions of exercise thermoregulatory stress. The experimental protocol consisted of 120 min of stationary upright cycling at 50% Vo₂max under conditions of neutral (24ºC, 50% RH)/euhydration (NE), hot (35°C, 50% RH)/euhydration (HE), and hot/dehydration (HD). Piβ-EN was measured by radioimmunoassay at -30 min, 0 min, and at 15 min intervals thereafter. Change in plasma volume (ΔPV) was measured to determine its effect on Piβ-EN concentration. Preexercise Piβ-EN levels averaged 23.7 ± 2.6 pg•ml⁻¹ in all conditions. The greatest Piβ-EN response occurred at 105 min in HD conditions when levels rose to 43.2 ± 6.9 pg•ml⁻¹. Exercise in HD and HE conditions resulted in significantly (p < 0.05) elevated Piβ-EN above levels observed in NE. ΔPV did not account for more than 10% of Piβ-EN changes at any interval. The Piβ-EN response pattern closely resembled rectal temperature changes in all conditions. These data suggest that conditions of increasing exercise thermoregulatory stress are associated with increasing peripheral β-endorphin concentration. / Master of Science

Ten well trained cyclists were studied and compared with 12 untrained subjects from a previous study to determine the effects of a high intensity, constant workload bout of cycling on maximum expiratory pressure (Pe_max). Subjects completed a graded exercise test on a Monark cycle ergometer while expired gases were collected to determine maximal oxygen consumption (VO_2max). Subjects then returned on a second day when measurements of each subject's Pe_max, were made prior to riding at the workload corresponding to 90% of their VO_2max until exhaustion. Measurements of expiratory pressure (Pe) were then made immediately post exercise (Pe_IPE), one minute post exercise (Pe_1MIN), three minutes post exercise (Pe_3MIN), and five minutes post exercise (Pe_5MIN). Trained cyclists had a significantly higher Pe_max (x = 116.43 ± 7.76 mmHg) than did untrained subjects (x = 65.75 ± 7.09 mmHg). Also trained cyclists generated a higher absolute Pe throughout recovery than did the untrained subjects. Although expiratory pressure decreased after exercise in both groups, the relative change in Pe over the recovery period, expressed as a percentage of Pe_max, was not different between trained and untrained. Pe_IPE was decreased to 81.87% ± 3.12 of Pe_maxin trained subjects and 82.35% ± 2.85 in untrained subjects (p < .05), recovering somewhat at 1 minute to 89.19% ± 3.59 of Pema, in trained and to 87.74% ± 3.27 in untrained (p < .05) but did not recover to resting levels in either group. Pe_3MIN and Pe_5MIN remained at the same level as Pe_1MIN in both groups. Therefore, a high intensity, short term exercise bout caused expiratory pressure to be decreased in both trained and untrained subjects. / Master of Science

Thirteen male college students volunteered to participate in this study. All subjects were students at Virginia Tech University and were between the ages of 18 and 34. The subjects were studies to determine their blood pressure responses to two weight lifting movements. Statistical significance was found for all conditions of systolic blood pressure and for peak diastolic blood pressure. It was concluded by the investigator that systolic blood pressure response is positively affected by both the mode of exercise and the loading of the exercise. / M.S.

This investigation used a constant-load cycle ergometer as a way of examining relationships between the cycle ergometer and sprint performance. Twenty-five college-aged males were used for this investigation. Following a three minute warm-up, each subject performed a 15 sec. maximal bout on the cycle ergometer. The resistance load on the ergometer was set at 0.12kg/kg of bodyweight. Peak power (PP), average power (AP), time to peak power (TTPP), power fatigue rate (PFR), and power fatigue index (PFI) were computed using a microcomputer system. In addition, PP,AP, and PFR were adjusted for total bodyweight (PP/kg, AP/kg, PFR/kg). On a separate day each subject performed six sprints two each at 50m, 100m, and 200m. Each sprint was electronically timed using an infra-red motion detector and starting blocks were used. Initially low correlations were found between the ergometer parameters and the sprint times (r=.07-.55). However upon closer evaluation stronger relationships appeared to exist for the faster subjects. Therefore, subject subgroups of faster subjects were formed. Subject subgroups for the 5 Om (T<7.5sec.), 100m (T<l4sec.)}, and 200m (T<26.6sec.) showed higher correlations (r=.06-.70). Further analysis revealed that high inter-variable correlations existed between many of the ergometer variables. Based on these correlations the parameters were separated into four groups. Group I contained variables of absolute power (PP,AP), group II were variables of relative power (PP/kg, AP/kg), group III contained variables of fatigue (PFR, PFI, PFR/kg), and group IV consisted of the acceleration variable (TTPP). Equations for predicting sprint performance were developed using one to four variables with only one variable from each group being used. The best equation was considered to be the one that yielded the highest r* value while also yielding the lowest Akakai Information Criteria value and MSE. Variables from the relative power group (PP/kg, AP/kg) and fatigue group (PFR, PFI, PFR/kg) were the best indicators of performance. These results suggest that the cycle ergometer used in this investigation can be used for evaluating the components of sprint performance in untrained males, and that this test is best when compared to the 200 m dash. / Master of Science

Three investigations were conducted using pulsed Doppler echocardiography (PDE) and oxygen consumption to non-invasively determine the relationship between hemodynamic and metabolic variables from rest through submaximal and maximal exercise in early adolescent males. In the first study, interinvestigator and day-to-day variability of cardiac output measurements at rest and during exercise determined by PDE were analyzed in six junior high school age boys. Four Doppler-derived variables (cardiac output, cardiac index, stroke volume, and stroke index) were not different when calculated by independent investigators and showed the same interinvestigator variability from rest through submaximal and maximal exercise as has been reported at rest in previous validation studies. There was a slight but statistically significant increase in the absolute values of the above hemodynamic variables and simultaneously collected metabolic variables during a second identical test conducted approximately nine days later. A faster adjustment to increasing workrates in the second test could explain this latter finding since supine cycle ergometry is not as familiar an activity as more frequently used modes of exercise testing. It is concluded that hemodynamic measurements using PDE exhibit the same acceptable variability throughout exercise as has been previously demonstrated at rest. In the second study, PDE was used to determine rapid serial measurements of cardiac output during a rapid loading supine cycle ergometer exercise test in twenty-two junior high school age boys. These measurements were compared to simultaneoulsy determined measurements of oxygen consumption. Cardiac output adjusted faster to each new workrate than oxygen consumption. Further analysis of these responses revealed that increases in heart rate (as opposed to stroke volume) were responsible for this rapid adjustment. It is concluded that there is an uncoupling and recoupling of these normally closely related hemodynamic and metabolic variables during the transitional periods between increasing levels of steady-state supine exercise. In the final study, gradual loading and rapid loading supine cycle ergometer protocols were compared in fifteen junior high school age boys. Maximal metabolic measurements and heart rate from each test were not different. Maximal PDE-derived measurements of cardiac output, cardiac index, stroke volume, and stroke index were slightly, but significantly, higher in the gradual loading protocol. It is concluded that a more complete adjustment of cardiac output (reflected by stroke volume) to maximal supine exercise occurs in a more gradual loading protocol than in a rapid loading protocol.

Studies assessing the reliability of the Borg rating of perceived exertion (RPE) scale for regulating exercise training intensity have reported mixed results. Differences in experimental designs and analytical techniques make it difficult to compare results. The purpose of this study was to examine the reliability of perceptually-based treadmill (TM) exercise. Eleven subjects (42.5 ± 19.5 yrs) completed a maximal test (GXT) and 3 RPEproduction trials (PT) on a TM. Each PT consisted of two 10-minute bouts where subjects selected speeds and grades to elicit an intensity equated with an RPE of 11-12 (RPE-L) and RPE of 15-16 (RPE-H). Speed and grade, heart rate (HR), oxygen uptake (V02), and ventilatory equivalent for oxygen (VE/V02) were assessed throughout the GXT and the last 3 minutes of each PT. Blood lactate concentration (BLC) was assessed at RPE-L and RPE-H during the GXT and at the completion of each PT intensity. Reliability was assessed using an ANOVA with repeated-measures, intraclass correlations, and absolute differences (ABS A) across the PTs at each intensity. No significant meangroup differences were noted in any of the physiological variables at either intensity across the PTs. Reliability coefficients were higher for the selected workload and the metabolic measures than for HR or BLC. Reliability increased across trials for all measures, and as a function of intensity for V02 (L = 0.91 & H = 0.98), HR (L = 0.60 & H = 0.84), and BLC (L = 0.50 & H = 0.64). Mean ABS A evaluated the inter-trial reliability for HR (bpm) and V02 (METS) at the low intensity PT 1 vs. PT2 = 013 bpm; A3.3 METS, PT 1 vs. PT3 = 010 bpm ; A3.3 METS, and PT2 vs. PT3 = A7 bpm; 01.6 METS and the high intensity PT 1 vs. PT2 = 011 bpm; A2.5 METS, PT 1 vs. PT3 = 011 bpm; A3.4 METS, and PT2 vs. PT3 = A9 bpm; A2.2 METS, respectively. Mean ABS A decreased for HR and V02 between PT2 vs. PT3. These data suggest that reliability of perceptually-based TMexercise varies among physiological measures and various analytical techniques, and individual variation in physiological data across PTs should be considered prior torecommending RPE for the self-regulation of exercise. / School of Physical Education

The purpose of this study was to determine the construct validity of self-reported historical walking, running, and jogging (WRJ) activity. The criterion measure was concurrent performance on a maximal treadmill test. Subjects completed a medical exam and treadmill test between the years 1976 and 1985, and completed a follow-up questionnaire in 1986. Questionnaire included an item that assessed WRJ for each year from 1976 through 1985. Data analysis included Spearman correlations, partial correlations, ANOVA, and ANCOVA. Results indicated self-reported historical WRJ can be assessed with reasonable validity when compared with concurrently measured treadmill performance, and there is no decay in the accuracy of this reporting for up to ten years in the past.

The purpose of this study was to describe mathematically the oxygen uptake kinetics during cycle ergometry, and to examine the effect of intensity on the kinetic responses within the severe domain. Sixteen volunteers performed a series of exercise tests at a range of intensities selected to elicit fatigue in ~3 to 10 min. A simple mono-exponential model effectively described the response across all intensities. There was a positive correlation between the response time and the time to fatigue, demonstrating that the maximal oxygen uptake was achieved faster at higher intensities within the severe domain. Models incorporating two components effectively described the responses only in tests lasting 8 min or more. It was concluded that there is a second, slow component in the oxygen uptake response only at the lower intensities within the severe domain.