This study examines factors that determine blood lactate accumulation during exercise in order to examine the opposing theories that such accumulation occurs either as a result of muscle anaerobiosis or an "overflow" of oxygen-independent glycolysis.

The purpose of this study was to determine whether the Cooper 12 Minute Run test and Bruce Multistage Treadmill test measure the same type of cardiovascular-endurance performance when testing adult women. A second purpose was to determine whether divergent levels of habitual activity by women are reflected in the scores on each test. Four groups of habitual activity were defined and labeled as follows: non-exercisers, minimal exercisers, adequate exercisers, and more than adequate exercisers. Ten healthy women were selected as subjects in each group. Subjects ranged in age from 22 to 35 years and were within the normal weight range according to standard tables. Each subject was tested in accordance with the appropriate protocol on the Bruce test and on the 12 Minute Run test. When individual scores for the two tests were correlated the data seemed to indicate that they were comparable measures of cardiovascular endurance performance. (r = 0.9097) An analysis of variance among group scores was performed for each test and highly significant F ratios were obtained. (F = 24.07 Bruce; F = 20.77 12 Minute Run) The most likely reason for the differences was seen as the divergent levels of habitual activity in each group. Contrasting tests were performed among groups and various combinations of groups. All test comparisons reached significance except for the one contrasting the 12 Minute Run scores of the two groups with the lowest activity levels. It was concluded that for the population of women at various levels of habitual activity who are represented by the selected sample in this study: the Bruce Multistage Treadmill test and the Cooper 12 Minute Run test measure largely the same type of cardiovascular endurance performance and that each test appears to adequately discriminate among women of divergent levels of habitual activity except at the lowest levels.

No description available.

No description available.

No description available.

The purpose of this study was to determine whether graded exercise test (GXT) variables known to have prognostic importance in the setting of severe-moderate coronary artery disease (CAD) and early post-myocardial infarction (MI) patients can also differentiate which physically active male patients with lesser disease and/or old MIs (undergoing serial GXT evaluation and an exercise maintenance program) will have a serious cardiac event, i.e., MI, coronary artery bypass surgery (CABG), or death. Data were obtained at two cardiac rehabilitation sites from three GXT results in 14 paired cardiac event (CE) and nonevent (NE) group subjects based on peak estimated oxygen consumption (VO_2estpk). Comparisons were also made with seven of these 14 paired group subjects for whom peak measured oxygen consumption (VO_2pk) were available. Statistical analyses were done on certain continuously-scaled, ordinally-scaled, and dichotomized dependent variables from selected GXTs. The continuously scaled dependent measures included VO_2estpk peak heart rate (HR_pk), resting heart rate (HR_rest), peak rise in exercise heart rate (HR_diff), peak systolic blood pressure (SBP_pk), rise in exercise systolic blood pressure (SBP_diff) and peak rate pressure product (RPB_pk), whereas, the ordinally-scaled dependent measures included functional aerobic impairment (FAI) and cardiac rehabilitation potential (CRP). For the dichotomized variables, ischemic ST-segment deviation at peak exercise (ischemic ST_dev} I exercise-induced ventricular dysrhythmias (VENT_dys) and exercise-induced chest pain were selected. Hotelling's T² test was utilized for analysis of the continuously- and ordinally-scaled dependent measures, whereas chi-square test was used for the dichotomized variables. There was a significant difference (F = 3.53; df = 3,11; p = .05) found between the paired CE-NE groups at and within each GXT time period for HR_diff in the 14 paired groups. Statistical analyses revealed no significant differences for any other variables in either the 14 paired and 7 paired groups. The small sample size limited the potential for statistical testing of the results in this study. However, the findings do appear to support that a poor chronotropic response indicated by HR_diff may have prognostic importance for those active CAD participants in supervised exercise maintenance programs who are at risk of a future cardiac event, i.e. MI, CABG, or death. / Master of Science

Six white volunteer males less than 35 years old, who ran less than 35 miles per week completed a loading regimen. This consisted of a succession of mixed, high-fat and highCHO diets for at least 72 hours each. Subjects ran to exhaustion after each diet stage. Mean times to exhaustion were 61, 63 and 95 minutes for the mixed, high-fat, and high-CHO diets, respectively. Since questions have been raised concerning a detrimental effect of CHO-loading on heart function, subjects were closely examined for evidence of negative effects associated with this procedure. An incomplete right bundle branch block (RBBB), sinus arrhythmia, and early repolarization after the mixed diet was noted in three of the six subjects. These changes were not observed during the high-fat nor high-CHO diets. Prior to the high-CHO exhaustive run, it was also found that the width of the QRS complex was significantly more narrow than the mixed and high-fat diets. The above electrocardiographic (ECG) changes were noted as not being clinically significant by an internal medicine physician. No changes were noted in blood pressures, serum free fatty acids (FFA) and post exhaustive run body weights for diets not pre/post exercise bouts. Serum glucose was significantly higher for the pre-run high-CHO diet when compared to the mixed and high-fat diets pre-run values, yet it remained within normal limits. Body weight following the high-CHO diet was significantly greater than during the high-fat and mixed periods. This may be due to water retention occurring with increased glycogen storage. This probably explains the longer time to exhaustion for the high-CHO diet as compared to the mixed and high-fat trials which both yielded similar times to exhaustion. Although research indicates that a mixed diet prolongs the onset of exhaustion more than a high-fat diet, the similar endurance capacity for the high-fat and mixed diets could be related to a learning effect on the treadmill and/or psychological considerations of consuming a high-fat diet. Also since heart rate and blood pressure were not significantly different for the first 30 minutes of exercise while rate of perceived exertion (RPE) indicated the mixed diet trial most demanding and the high-CHO trial least, one might suspect that some other factor besides physiological values, may cause fatigue. In summary, CHO-loading appeared to enhance endurance of the novice runner with no apparent detrimental effects on cardiac function in these six subjects. / Master of Science

Twenty-eight endurance trained male volunteers, 18-41 years or age, were studied to determine whether the heart rate-oxygen consumption relationships observed during Bruce protocol stress tests were similar to those observed during steady-state exercise. In addition, maximal oxygen consumption and maximal heart rate values obtained during the stress tests were compared to predicted values. The heart rate-oxygen consumption relationship observed during the stress tests was dissimilar from the relationship observed during the steady-state exercise tests. Heart rate was round to be significantly higher during the stress tests. No significant difference was round in predicted maximal oxygen consumption and maximal heart rate and actual values obtained during the stress tests. / M.S.

The American College of Sports Medicine has published formulae that are widely used to predict functional aerobic capacity for any treadmill speed and grade combination. However, it has been demonstrated that these formulae overpredict oxygen consumption (V̇O₂) for patients with coronary artery disease as well as for apparently healthy individuals. To study this, we measured V̇O₂, ventilation (V̇_E), and respiratory exchange ratio (R) responses in 21 apparently healthy subjects (AH) and 16 coronary artery diseased subjects (CAD) during a modified Balke protocol. Modification of the protocol consisted of extending the stage time from two minutes to three minutes at the higher intensities to allow a greater time for a physiological steady-state to occur. The attainment of a steady-state may lead to the reduction of or the elimination of prediction errors. No differences were observed between two and three minute VO₂ responses at maximal and submaximal exercise for either group. At peak exercise, the AH group was significantly (P≤.05) different from the CAD group when compared for heart rate (164±2.6 vs 140±4.8 bts•min⁻¹ ), V̇O₂ (33.3±1.1 vs 26.7±2.3 ml•kg⁻¹•min⁻¹), and total treadmill time (9.9±.33 vs 8.1±.54 min). At submaximal exercise, V̇O₂ responses were also significantly (p≤.05) greater for the AH group when compared to the CAD group (26.6±.95 vs 21.9±1.8 ml•kg⁻¹•min⁻¹). No significant differences were observed for RPE and blood lactate at peak exercise and V̇_E and R responses at submaximal or peak exercise between the two groups. Predicted values for peak V̇O₂ were significantly (p≤.05) higher than measured values (33.3±1.1 vs 38.8±1.1 ml•kg⁻¹•min⁻¹) and (26.7±2.3 vs 34.1±1.7 ml•kg⁻¹•min⁻¹) for the AH and CAD groups, respectively. However, no significant differences were noted between predicted and measured V̇O₂ responses at submaximal exercise for either group. Individuals classified as Type A were not significantly different from classified Type B individuals when compared for the cardio-respiratory variables measured. These data demonstrate that the ACSM prediction formulae significantly overpredict V̇O₂ for both AH and CAD subjects at maximal treadmill intensities. However, at submaximal intensities, these prediction formulae are acceptable for both groups of subjects. Furthermore, these data suggest that two minutes per stage allows sufficient time for physiological steady-state to occur at clearly submaximal intensities. Although at the higher intensities, extending the stage time beyond two minutes may be indicated. / M.S.

Continuous-wave (CW) Doppler recordings of ascending aortic maximal blood flow acceleration (PkA), maximal velocity (PkV) and systolic velocity integral (SVI) were taken at each stage of a graded exercise treadmill test on two separate days with 30 physically active adult males. Signals were measured (Quinton Exerdop) for all cardiac cycles in the 3rd minute of each stage using a hand-held probe positioned at the suprasternal notch. A dedicated microcomputer, programmed to select "valid" beats on the basis of value consistency in the sample set, determined the acceptability of signals. No significant differences were found between the three trial means within each stage on either day for PkA, PkV or SVI. Significant (p <.01) intraclass reliability estimates ranged from r = 0.89 to 0.97 (Pk.A), r = 0.90 to 0.98 (PkV) and r = 0.85 to 0.95 (SVI) . Coefficients of variation were calculated at each stage to estimate the relative consistency of each measure. A gradual reduction of the coefficient of variation was observed for each blood flow measure between stages one and four. The test-retest (between days) reliability coefficients for PkA, PkV and SVI for stages one to four ranged between r = 0.51 to 0.78 (P <.004), but correlations for the pre-exercise baseline and stages five and six were lower. These results indicate that (1) PkA, PkV and SVI demonstrate greater measurement stability within each stage of a graded exercise test than is the case between separate days of measurement at the same stage; and (2) there is modest day-to-day response stability for clinical testing with the Doppler parameter of PkV. Reliability/stability was best in exercise stages which encompass the speed and grade range of 45.0 m•min⁻¹/10%. - 111.7 m•min⁻¹/14%, i.e., those in which all subjects can walk. / Master of Science