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Assessed the effects of frequency of prompting (phone calls once a week versus once every three weeks) and content of prompting (feedback and goal setting versus "touching base") in a walking program designed to meet ACSM's cardiovascular exercise goals. Survival analysis using six months of data points and using the criteria of walking at least 20 minutes a day for a at least three times per week indicated an effect for more frequent versus less frequent prompting (50% and 15%), but not for feedback and goal setting versus "touching base" prompting (31% and 30%). The results suggested the efficacy of frequent prompting delivered in inexpensive ways as a means to increase exercise adherence and the further parametric study of other basic behavior change strategies. / Ph. D.

Effects of fat adaptation and NaHC0₃ supplementation on acid-base homeostasis were quantitated during repeated sprint exercise in horses. Contribution of strong ions ([SID]), Pco₂, and weak electrolytes ([A_tot]) to changes in plasma [H⁺] and the role of erythrocytes in acid-base balance were examined at rest and during exercise. Effects on plasma glucose and blood lactate [Lac⁻] concentrations due to sample handling were also assessed. During exercise, blood [Lac⁻] was higher when horses received NaHC0₃ compared to water prior to exercise (P=0.0024), and in fat adapted horses compared to horses fed a control diet (P=0.0240). Blood [Lac-] was higher in fat adapted horses given NaHC0₃ compared to other diet/treatment combinations (P=0.0276). Plasma [SID] was higher during exercise when horses were given NaHC0₃ compared to plain water (P=0.0054), which contributed to decreasing [H⁺] and increasing [HC0₃⁻] during exercise (P=0.0001). Plasma Pco₂ contributed less to increasing plasma [H⁺] during exercise in fat-adapted horses compared to horses fed the control diet (P=0.0282). Intraerythrocyte [SID] decreased (P=0.0160) and [Atod increased (P=0.0002) which contributed to increasing [H⁺] within the cell (P=0.0228). / Ph. D.

The purpose of this study was to determine the effect of prostaglandin (PG) inhibition on the sympathetic and pressor responses to isometric handgrip (HG) at 40% of maximal voluntary contraction (MVC) to exhaustion and postcontraction muscle ischemia (PC). To accomplish this heart rate (HR), arterial pressure (n=10) and plasma norepinephrine (NE) levels (n=8) were measured in 10 healthy male subjects during HG at 40% of MVC to exhaustion and during PC. The subjects were given a double-blind administration of either placebo (PLAC) or a single 100 mg dose of indomethacin (IND). The order of administration was counterbalanced and a one week drug washout period was provided between conditions. Mean arterial pressure increased 25±5 vs. 22±4 mmHg during the second minute of HG and 26±2 vs. 21±5 during the last minute of PC in PLAC vs. IND (P>.05), respectively. Heart rate was increased 21±4 vs. 17±3 bpm during the second minute of HG in PLAC vs. IND (P>.05), respectively and returned to control values during PC in both trials. Plasma NE increased 343189 vs. 289±89 pg/ml after HG and 67514132 vs. 6324132 pg/ml after PC (P>.05) in PLAC vs. IND, respectively. Therefore, PG inhibition does not alter sympathetic or arterial pressure responses during sustained isometric exercise in humans. This may suggest that 1) PGs not important in metaboreceptor stimulation of sympathetic or pressor responses to sustained isometric contractions in humans or 2) PGs may play only a small role in the regulation of these variables which may be masked by the effects of other stimuli. Index terms: prostaglandins, pressor reflex, muscle sympathetic nerve activity, static exercise / Ph. D.

This study investigated the differences in the cardiovascular reactivity (CVR: HR, SBP, DBP) of trained and untrained individuals who performed the cold pressor test (CPT) after exercising for 30 minutes at 70% VO₂ max and participating in an attention control. Eighteen untrained and eleven trained males were randomly assigned to a treatment sequence. The subjects performed either 30 minutes of cycling at 70% VO₂ max Or an attention control. Following 48 hours, the other activity was performed. The CPT followed 1 hour after each treatment session. Rest, peak, and recovery measurements were acquired. Examination of trained and untrained group means, regardless of condition, indicated that trained subjects had lower HR measurements at rest (F_1,25 = 6.86, p < .05) and peak (F_1,25 = 6.33, p < .05). Closer examination of the different effects due to the acute exercise and control conditions regardless of training state did not reveal any beneficial effects due to the exercise bout. In addition, this study did not support differences in CVR to the CPT due to an interaction of acute exercise with the trained and untrained states of individuals. Resting measures did reveal reduced DBP (F_1,25 = 4.06, p < .05) and HR (F_1,25 = 3.19, p = .09) in trained subjects compared with the untrained following the exercise session indicating a beneficial reduction in the anticipatory response to the stressor. This study did not statistically support the effectiveness of 30 minutes of exercise at 70% VO₂ max or advantages of a physically trained state in reducing CVR to the CPT. In addition, this study did not support the effectiveness of the interaction of exercise at 70% VO₂ max with the trained or untrained state in reducing CVR to the CPT. / Master of Science

Six adult male volunteers of similar body size (x̄ ± SD:ht = 184.6 ± 6.4 cm; wt = 80.86 ± 2.7 kg) and aerobic exercise capacity (VO₂ = 38 ± 3.1 ml·kg⁻¹. min⁻¹) were tested to determine what physiological and perceptual differences existed during endurance cycling using a Powercam (Houdaille, Inc.) crank system (CAM) as compared to a standard crank system (STD). Following preliminary tests to determine the subject's working capacity, each was assigned to ride either in the CAM or STD mode for 1 hour using a gear ratio that would require an effort equal to 70% of the VO₂ max. After a minimum of 72 hours between trials, subjects were retested in the converse mode. Measurements that included HR, BP, VO₂, surface EMG, and RPE were monitored at 15 minute intervals during both tests. Responses were very similar across modes and between subjects. Although subjects demonstrated responses that may indicate an improved efficiency for a particular mode, the group did not display patterns that would indicate efficiency for the Powercam crank system. / M.S.

Five adult male volunteers were studied to investigate the effect of opiate receptor blockade on the physiological response to a maximum of 60 minutes of stationary cycling at 70% V02peak in a hot (33 0 C/65% RH) environment. Exercise bouts were conducted following the administration of naloxone (4mg IV) 5 minutes prior to exercise with a follow-up 4mg dose at 25 minutes of exercise. In the placebo trial, volume-matched doses of saline were administered at the same points. No significant drug effect was observed on rectal or mean skin temperature during exercise. Post-exercise skin temperature was significantly (P<.001) higher on naloxone versus saline. Forearm blood flow (FBF) was consistently higher from minute 25 of exercise until test termination, although only the minute 25 and minute 55 data points were significantly elevated (P<.05, P<.005, respectively) . The rectal temperature threshold at which FBF plateaued was higher on naloxone (P=.054), and the FBF: rectal temperature slope was higher on naloxone throughout the trial. No significant changes were observed in heart rate or estimated mean arterial pressures, although both were consistently lower on naloxone. Gross sweat response was not altered by the drug. Plasma Beta-Endorphin was significantly (P<.Ol) higher on naloxone versus saline, and Beta-Endorphin was significantly elevated in the naloxone trial only. The observation that FBF was significantly higher on naloxone without inducing compensatory heart rate or blood pressure changes suggests that the opioids may be involved in the blood volume shifts that occur during prolonged exercise in the heat. / Master of Science

The purpose of the study was to determine whether serial graded exercise test (GXT) responses, known to have prognostic importance, in the coronary artery disease population generally, can differentiate certain cardiovascular morbidity and mortality endpoints among physically active patients. Data were obtained in 1989 at three community-based cardiac rehabilitation programs from three serial GXT results in 23 paired cardiac event (CE) and non-event (NE) patients. A cardiac event was defined as having an myocardial infarction (MI), percutaneous translumial angioplasty (PTCA), coronary artery bypass grafting (CABG), and cardiac death. Comparisons were made just prior to each CE patients event. Statistical analyses were done on four exercise test variables: ST-segment depression (ST80) at peak exercise, heart rate adjusted 5Tsegment depression (ST/HR slope), exercise induced ventricular dysrhythmias (PVC), and exercise induced chest pain. Chi-square analyses showed no significant changes across the serial tests for any of the variables examined in either the CE or NE groups (P)0.05). Nevertheless, the CE group had significantly more 8Tsegment depression, ST/HR slope, and exercise chest pain in all GXT intervals in comparison to the NE group. These findings do not support the use of serial exercise GXTs for prognostic information for the physically active cardiac rehabilitation maintenance patients. / Master of Science

This investigation assessed the effects of acute exercise on blood pressure (BP) during a person's day-to-day life. It was hypothesized that there would be a reduction of systolic BP (SBP) and diastolic BP (DBP) at 1, 3, 5, and 7 hours following exercise as compared to a control condition. Additionally, it was speculated that those subjects with a greater reactivity to the cold pressor task would show a larger reduction than all subjects in mean BP. A secondary hypothesis was that there would be an attenuation of cardiovascular reactivity (CVR) following exercise. Fifteen college aged students enrolled in health education courses at Virginia Tech wore an ambulatory blood pressure (ABP) monitor for 2 days. These days were scheduled to be as equivalent in demands and activities as possible. On the morning prior to monitoring they took part in either an exercise or a control condition. During the exercise session they cycled for 30 minutes at 10% of their V02max. On the control day, they read for 30 minutes. The order of these two conditions was counterbalanced across subjects. Subjects then wore the ABP monitor for 12 hours while engaging in their usual activities. It was programmed to take readings every 20 minutes. A self-monitoring diary was filled out immediately following each cuff inflation. No significant differences were found between exercise and control days in either mean SBP or mean DBP. A subset of subjects most reactive to the cold pressor test also failed to show a significant effect. An analysis of standard deviations of mean BP did not reveal significant differences in CVR between the treatment and the control day. The selfmonitoring data indicated no significant differences across days in mood, stress, perception of the environment, and position/activity. This study does not support the hypothesis that SBP and DBP are attenuated during a person's daily activities following acute exercise. A number of limitations, however, might have reduced the power of the analysis. Differing schedules and demands between testing days may have introduced random error. In addition, the subjects tested have a number of characteristics which possibly render them relatively unresponsive to the exercise intervention. Future research, in which these limitations are corrected, will be necessary to determine if exercise exerts an acute effect on mean BP in the natural environment in populations at greater cardiovascular risk. / Master of Science