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PubMed1987

Exercise testing for sports and the exercise prescription.

The uses of the exercise test continue to grow and diversify. Familiarity with the mechanics, logistics, and interpretation of these tests leads to their optimal use. The application of exercise testing for competitive or recreational sports, cardiovascular fitness exercise training, and cardiac rehabilitation is the focus of this review. Many test protocols are available, but treadmill testing is the most widely used. The inclusion of thallium scintigraphy in the exercise protocol requires additional time and expense and is best reserved for those in whom the exercise electrocardiographic response cannot be adequately interpreted. Exercise testing is a relatively safe procedure, providing that adequate screening of individuals for unstable cardiac or medical conditions has been performed. The test must be administered by experienced personnel in a setting where the necessary emergency resuscitative equipment is available. Adequate interpretation of the exercise test requires knowledge of the individual being tested and of the reason the test is being performed. Complete analysis of the exercise test includes electrocardiographic response (ST segment changes and rhythm disturbances), hemodynamic response (heart rate and blood pressure before, during, and after exercise), and functional capacity (exercise duration, symptoms, conversion to MET's). When exercise tests are employed to establish a diagnosis of coronary artery disease, an assessment of the pretest likelihood (prevalence) of disease is essential in deriving a reasonable assessment of the probability of disease after the test has been performed and reviewed. This information is particularly important when screening asymptomatic subjects for underlying coronary disease before they engage in an exercise program. Exercise testing of individuals with known cardiac disease prior to engaging in competitive or recreational sports can yield much useful information. In addition to a knowledge of the underlying cardiac condition, the type and intensity of the sport being performed must be taken into account when exercise testing is performed for athletic screening. Individuals with congenital or acquired valvular heart disease, coronary artery disease, and rhythm disturbances should undergo an exercise test as part of the pretraining evaluation. Patients with ischemic heart disease, especially those who have had a recent myocardial infarction or have undergone coronary artery bypass surgery, require counseling regarding their ability to perform certain activities of daily living and to return to work. Exercise testing can be a useful tool in establishing activity guidelines for these individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1998

Exercise echocardiography or exercise SPECT imaging? A meta-analysis of diagnostic test performance.

CONTEXT: Cardiac imaging has advanced rapidly, providing clinicians with several choices for evaluating patients with suspected coronary artery disease, but few studies compare modalities directly. OBJECTIVES: To review the contemporary literature and to compare the diagnostic performance of exercise echocardiography (ECHO) and exercise single-photon emission computed tomography (SPECT) imaging in the diagnosis of coronary artery disease. DATA SOURCES: Studies published between January 1990 and October 1997 identified from MEDLINE search; bibliographies of reviews and original articles; and suggestions from experts in each area. STUDY SELECTION: Articles were included if they discussed exercise ECHO and/or exercise SPECT imaging with thallous chloride TI 201 (thallium) or technetium Tc 99m sestamibi for detection and/or evaluation of coronary artery disease, if data on coronary angiography were presented as the reference test, and if the absolute numbers of true-positive, false-negative, true-negative, and false-positive observations were available or derivable from the data presented. Studies performed exclusively in patients after myocardial infarction, after percutaneous transluminal coronary angioplasty, after coronary artery bypass grafting, or with recent unstable coronary syndromes were excluded. DATA EXTRACTION: Clinical variables, technical factors, and test performance were independently extracted by 2 reviewers on a standardized spreadsheet. Discrepancies were resolved by consensus. RESULTS: Forty-four articles met inclusion criteria. In pooled data weighted by the sample size of each study, exercise ECHO had a sensitivity of 85% (95% confidence interval [CI], 83%-87%) with a specificity of 77% (95% CI, 74%-80%). Exercise SPECT yielded a similar sensitivity of 87% (95% CI, 86%-88%) but a lower specificity of 64% (95% CI, 60%-68%). In a summary receiver operating characteristic model comparing exercise ECHO performance to exercise SPECT, exercise ECHO was associated with significantly better discriminatory power (parameter estimate, 1.18; 95% CI, 0.71-1.65), when adjusted for age, publication year, and a setting including known coronary artery disease for SPECT studies. In models comparing the discriminatory abilities of exercise ECHO and exercise SPECT vs exercise testing without imaging, both ECHO and SPECT performed significantly better than exercise testing. The incremental improvement in performance was greater for ECHO (3.43; 95% CI, 2.74-4.11) than for SPECT (1.49; 95% CI, 0.91-2.08). CONCLUSIONS: Exercise ECHO and exercise SPECT have similar sensitivities for the detection of coronary artery disease, but exercise ECHO has better specificity and, therefore, higher overall discriminatory capabilities as used in contemporary practice.

Coronary Disease↗
PubMed1996

A survey of exercise beliefs and exercise habits among people with arthritis.

OBJECTIVE: To explore a possible explanation for the problem of why few people exercise despite the positive health advantages, by examining the relationship between exercise beliefs and participation in exercise activities. METHODS: Eighty-one respondents aged 27-80 were recruited from 3 Chicago-area health care facilities to complete the study survey; 68 (84%) did so. Participants were asked about their participation in 6 types of exercise activities; they also reported their beliefs concerning their ability to exercise (self-efficacy for exercise), barriers to exercise, benefits of exercise, and the impact of exercise on their arthritis. RESULTS: Study results indicate that belief in the benefits of exercise and self-efficacy for exercise are associated with participation in exercise activities. Also, severity of disease differentiated exercisers from non-exercisers. CONCLUSIONS: Results suggest the importance of finding ways to strengthen belief in the benefits of exercise and self-efficacy for exercise in people with arthritis, particularly people with moderate to severe disease-related limitations.

Adult↗
PubMed1999

Hypotension following mild bouts of resistance exercise and submaximal dynamic exercise.

Our purposes were (1) to examine resting arterial blood pressure following an acute bout of resistance exercise and submaximal dynamic exercise, (2) to examine the effects of these exercises on the plasma concentrations of atrial natriuretic peptide ([ANP]), and (3) to evaluate the potential relationship between [ANP] and post-exercise blood pressure. Thirteen males [24.3+/-(2.4) years] performed 15 min of unilateral leg press exercise (65% of their one-repetition maximum) and, I week later, approximately 15 min of cycle ergometry (at 65% of their maximum oxygen consumption). Intra-arterial pressure was monitored during exercise and for 1 h post-exercise. Arterial blood was drawn at rest, during exercise and at intervals up to 60 min post-exercise for analysis of haematocrit and [alphaANP]. No differences occurred in blood pressure between trials, but significant decrements occurred following exercise in both trials. Systolic pressure was approximately 20 mmHg lower than before exercise after 10 min, and mean pressure was approximately 7 mmHg lower from 30 min onwards. Only slight (non-significant) elevations in [alphaANP] were detected immediately following exercise, with the concentrations declining to pre-exercise values by 5 min post-exercise. We conclude that post-exercise hypotension occurs following acute bouts of either resistance or submaximal dynamic exercise and, in this investigation, that this decreased blood pressure was not directly related to the release of alphaANP.

Adult↗
PubMed1999

Losartan improves exercise tolerance in patients with diastolic dysfunction and a hypertensive response to exercise.

OBJECTIVES: The aim of the study was to test the hypothesis that angiotensin II (Ang II) blockade would improve exercise tolerance in patients with diastolic dysfunction and a marked increase in systolic blood pressure (SBP) during exercise. BACKGROUND: Diastolic dysfunction may be exacerbated during exercise, especially if there is a marked increase in SBP. Angiotensin II may contribute to the hypertensive response to exercise and impair diastolic performance. METHODS: We performed a randomized, double-blind, placebo-controlled, crossover study of two weeks of losartan (50 mg q.d.) on exercise tolerance and quality of life. The subjects were 20 patients, mean age 64 +/- 10 years with normal left ventricular systolic function (EF >50%), no ischemia on stress echocardiogram, mitral flow velocity E/A <1, normal resting SBP (<150 mm Hg), and a hypertensive response to exercise (SBP >200 mm Hg). Exercise echocardiograms (Modified Bruce Protocol) and the Minnesota Living With Heart Failure questionnaire were administered at baseline, and after each two-week treatment period, separated by a two-week washout period. RESULTS: Resting blood pressure (BP) was unaltered by placebo or losartan. During control, patients were able to exercise for 11.3 +/- 2.5 (mean +/- SD) min, with a peak exercise SBP of 226 +/- 24 mm Hg. After two weeks of losartan, baseline BP was unaltered, but peak SBP during exercise decreased to 193 +/- 27 mm Hg (p < 0.05 vs. baseline and placebo), and exercise time increased to 12.3 +/- 2.6 min (p < 0.05 vs. baseline and placebo). With placebo, there was no improvement in exercise duration (11.0 +/- 2.0 min) or peak exercise SBP (217 +/- 26 mm Hg). Quality of life improved with losartan (18 +/- 22, p < 0.05) compared to placebo (22 +/- 26). CONCLUSIONS: In patients with Doppler evidence of diastolic dysfunction at rest and a hypertensive response to exercise, Ang II receptor blockade blunts the hypertensive response to exercise, increases exercise tolerance and improves quality of life.

Adult↗
PubMed1995

Gender and developmental differences in exercise beliefs among youth and prediction of their exercise behavior.

This study examined gender and developmental differences in exercise-related beliefs and exercise behaviors of 286 racially diverse youth and explored factors predictive of exercise. Compared to males, females reported less prior and current exercise, lower self-esteem, poorer health status, and lower exercise self-schema. Adolescents, in contrast to pre-adolescents, reported less social support for exercise and fewer exercise role models. In a path model, gender, the benefits/barriers differential, and access to exercise facilities and programs directly predicted exercise. Effects of grade, perceived health status, exercise self-efficacy, social support for exercise, and social norms for exercise on exercise behavior, were mediated through the benefits/barriers differential. Effect of race on exercise was mediated by access to exercise facilities and programs. Continued exploration of gender and developmental differences in variables influencing physical activity can yield valuable information for tailoring exercise promotion interventions to the unique needs of youth.

Adolescent↗
PubMed2003

Exercise heat stress does not reduce central activation to non-exercised human skeletal muscle.

In this study we measured the central activation ratio (CAR) of the leg extensors and the elbow flexor muscles before and after exhaustive exercise in the heat to determine whether exercise-induced hyperthermia affects the CNS drive to exercised (leg extensors) and/or non-exercised (forearm flexors) muscle groups. Thirteen subjects exercised at fixed intensities representative of a percentage of peak power output (PPO) for 10 min periods (50 %, 40 %, 60 %, 50 %) and then at 75 % PPO until exhaustion in ambient conditions of 39.3 +/- 0.8 degrees C and 60.0 +/- 0.8 % relative humidity. Before and immediately following exercise subjects performed a series of maximal voluntary contractions (MVCs) with the leg extensors (exercised muscles) and forearm flexors (non-exercised muscles). The degree of voluntary activation during the sustained MVCs was assessed by superimposing electrical stimulation to the femoral nerve and the biceps brachii. Exercise to exhaustion increased the rectal temperature from 37.2 +/- 0.2 to 38.8 +/- 0.2 degrees C (P < 0.0001). The mean heart rate at the end of exercise to exhaustion was 192 +/- 3 beats min(-1). Leg extensor voluntary force was significantly reduced from 595 +/- 143 to 509 +/- 105 N following exercise-induced hyperthermia but forearm flexor force was similar before and after exercise. The CAR of the leg extensors decreased from 94.2 +/- 1.3 % before exercise to 91.7 +/- 1.5 % (P < 0.02) following exercise-induced hyperthermia. However, the CAR for the forearm flexors remained at similar levels before and after exercise. The data suggest that the central nervous system selectively reduces central activation to specific skeletal muscles as a consequence of exercise-induced hyperthermia.

Adaptation, Physiological↗
PubMed1983

Exercise testing in asymptomatic or minimally symptomatic aortic regurgitation: relationship of left ventricular ejection fraction to left ventricular filling pressure during exercise.

Exercise radionuclide angiography is being used to evaluate left ventricular function in patients with aortic regurgitation. Ejection fraction is the most common variable analyzed. To better understand the rest and exercise ejection fraction in this setting, 20 patients with asymptomatic or minimally symptomatic severe aortic regurgitation were studied. All underwent simultaneous supine exercise radionuclide angiography and pulmonary gas exchange measurement and underwent rest and exercise measurement of pulmonary artery wedge pressure (PAWP) during cardiac catheterization. Eight patients had a peak exercise PAWP less than 15 mm Hg (group 1) and 12 had a peak exercise PAWP greater than or equal to 15 mm Hg (group 2). Group 1 patients were younger and more were in New York Heart Association class I. Group 1 patients also had a higher mean rest ejection fraction (0.64 +/- 0.08 vs 0.49 +/- 0.13, p less than 0.01, higher exercise ejection fraction (0.63 +/- 0.10 vs 0.40 +/- 0.18, p less than 0.01), lower end-systolic volume (38 +/- 13 vs 79 +/- 36 ml/m2, p less than 0.01) and higher peak oxygen uptake (24.9 +/- 5.1 vs 16.6 +/- 4.9 ml/kg/min, p less than 0.01) than group 2 patients. However, the two groups had similar cardiothoracic ratios, changes in ejection fractions with exercise, and rest and exercise regurgitant indexes. Using multiple regression analysis, the best correlate of the exercise PAWP was peak oxygen uptake (r = -0.78, p less than 0.01). No other measurement added significantly to the regression. When peak oxygen uptake was excluded, rest and exercise ejection fraction also correlated significantly (r = -0.62 and r = -0.60, respectively, p less than 0.01). Patients with asymptomatic or minimally symptomatic severe aortic regurgitation have a wide spectrum of cardiac performance in terms of the PAWP during exercise. The absolute rest and exercise ejection fraction and the level of exercise achieved are noninvasive variables that correlate with exercise PAWP in aortic regurgitation, but the change in ejection fraction with exercise by itself is not.

Adolescent↗
PubMed2005

Comparison of supervised exercise training and home-based exercise training in chronic heart failure.

OBJECTIVE: This study was planned to compare the outcomes between supervised and home-based exercise training in patients with chronic heart failure. METHODS: The study was conducted at the Department of Physical Therapy in Ankara University, Faculty of Medicine, Turkey between 2000 and 2001. Twenty-two patients with stable chronic heart failure were randomly assigned to the supervised exercise training group (n=11) or the home-based exercise training group (n=11). Symptom-limited maximal exercise tests with gas exchange analysis were carried out before randomization. Work load equivalent to 60% of achieved peak heart rate at the tests was determined as exercise training work load for each subject. Both groups participated in a program of 3 exercise training sessions per week for 3 months. The exercise tests were repeated after 3 months. RESULTS: After training, peak exercise duration increased significantly in the supervised exercise training group and the home-based exercise training group (p<0.05). There was substantial improvement in peak VO2 with exercise training in the supervised exercise training group (p<0.05) but, peak VO2 did not change significantly in the home-based exercise training group (p>0.05). CONCLUSION: Supervised and home-based exercise training enhanced exercise capacity in patients with chronic heart failure. The training program must be tailored to each patient's specific limitations, individual needs and possibilities. Home-based exercise training may be a training alternative to stable chronic heart failure patients who prefer not to participate in an outpatient supervised training program.

Chronic Disease↗
PubMed1996

Exercise-induced coronary spasm: comparison of treadmill and bicycle exercise in patients with vasospastic angina.

BACKGROUND: We investigated whether exercise-induced coronary spasms are influenced by the different exercise modes. METHODS: We compared ischaemic ECG responses in 67 patients with vasospastic angina who underwent both treadmill and bicycle ergometer exercise and also coronary angiography. RESULTS: ECG ST-segment elevation was provoked more frequently during treadmill exercise than it was during bicycle exercise (19 versus 9%, P < 0.05). Of 45 patients without significant coronary stenosis (coronary artery luminal diameter narrowing < 75%), 19 patients manifested ST-segment depression during treadmill exercise, whereas only seven patients did during bicycle exercise (42 versus 16%, P < 0.01). All patients with ST-segment elevation or depression during bicycle ergometer exercise also had ST-segment changes during treadmill exercise. Although higher systemic blood pressure levels and lower heart rates were found during bicycle exercise compared with during treadmill exercise the pressure-rate products at peak exercise did not differ between the two exercise tests. CONCLUSIONS: It seems that treadmill and bicycle exercise are different stressors in patients with vasospastic angina, and that coronary spasms are provoked more frequently during treadmill exercise than they are during bicycle exercise. The cause of this difference is not known, but it may be related in part to the difference in systemic haemodynamic or neurohumoral response.

Adult↗
PubMed1991

Effect of exercise training on multiple respiratory variables in patients with coronary artery disease: correlation with change in exercise capacity.

Multiple measurements of pulmonary function were performed during exercise testing in 29 patients with coronary artery disease (CAD) before and after exercise training. Following training, significant increases in oxygen consumption (VO2), carbon dioxide production (VCO2), and peak flow at maximal exercise were seen as compared with pretraining values (p less than .01), but not in any other respiratory variables. Only the peak respiratory exchange ratio (RER) achieved during pretraining exercise testing and peak values of minute ventilation (VT), respiratory rate, and VCO2 during a posttraining exercise test showed significant correlations with the change in maximum VO2 following exercise training (p less than .05). Significant correlations were also found among VT, VCO2, and peak flow at peak exercise following exercise training and the change in exercise duration between pretraining and posttraining stress tests. Of 22 patients evaluated with thallium 201 scintigraphy during their pretraining exercise test, 11 developed ischemic ST depression or a reversible perfusion defect. No significant differences in pulmonary function measurements during exercise testing were seen between patients who developed ischemia and those who did not. However, the change in peak metabolic equivalents (METS) achieved between pretraining and posttraining exercise was significantly greater in patients who developed ischemia (.836 +/- 1.003 versus .091 +/- .481, p less than .05). These results indicate that exercise training in patients with CAD is not associated with significant changes in most measurements of pulmonary function and, with the exception of RER at peak exercise, pretraining measurements do no show a significant correlation with changes in exercise capacity.

Aged↗
PubMed1996

Cortisol response to exercise and post-exercise suppression of blood lymphocyte subset counts.

This study examined a temporal relationship between exercise-induced changes in blood cortisol levels and circulating leukocyte and lymphocyte subset counts during and after exercise. Twenty-one young male, sedentary subjects [mean age, 20.8 +/- 2.4 (SD) yr; mean VO2max, 48.0 +/- 7.9 (SD) ml/kg/min] underwent a cycle ergometer exercise for 60 min at 60% VO2max. Peripheral blood samples, collected every 30 min during exercise and at 30, 60 min, 2.5 and 6 h of recovery, were used for the determination of serum cortisol and plasma catecholamines; lymphocyte subsets were analyzed by flow-cytometry. Based on the analysis of serum cortisol levels in response to exercise, the subjects can be identified as two groups: cortisol-responder (n = 13) and non-responder (n = 8) groups. Other than the cortisol response, the two groups showed no significant differences in terms of age, physical build, aerobic fitness, maximal heart rate, and pre-exercise blood leukocyte and lymphocyte subset counts. The two groups also did not differ significantly in their relative work rate and catecholamine response to the exercise. Both cortisol responder and non-responder groups displayed a granulocytosis, lymphocytosis and monocytosis during exercise, and a further granulocytosis after exercise. Changes in lymphocyte count and distribution during recovery, however, differed significantly between the two groups. In the circulation of the cortisol non-responder group, total lymphocyte counts returned to the baseline level shortly after exercise, whereas a significant lymphopenia occurred at 2.5 h of recovery in the cortisol responder group: the CD4+ cells showed the greatest decrease in cell count, followed by the CD8+ cells. In both groups, the CD16+ cell-counts tended to decline below the pre-exercise values at 30 and 60 min of recovery and returned to the baseline values by 2.5 h of recovery. The CD19+ cell-count was not suppressed in both groups after exercise. These results suggest that exercise-induced secretion of blood cortisol may contribute to post-exercise suppression of the helper- and cytotoxic-T cell counts, but does not seem to be involved in post-exercise changes in the NK-cell and B-cell counts as well as in post-exercise granulocytosis.

Adult↗
PubMed1999

Effects of intermittent exercise and use of home exercise equipment on adherence, weight loss, and fitness in overweight women: a randomized trial.

CONTEXT: Enhancing participation in long-term exercise may translate into improved long-term weight loss in overweight adults. OBJECTIVES: To compare the effects of intermittent with traditional continuous exercise on weight loss, adherence, and fitness, and to examine the effect of combining intermittent exercise with that using home exercise equipment. DESIGN: Randomized trial from September 1996 through September 1998. SETTING AND PARTICIPANTS: A total of 148 sedentary, overweight (mean [SD] body mass index, 32.8 [4.0] kg/m2) women (mean [SD] age, 36.7 [5.6] years) in a university-based weight control program. INTERVENTIONS: Eighteen-month behavioral weight control program with 3 groups: long-bout exercise (LB), multiple short-bout exercise (SB), or multiple short-bout exercise with home exercise equipment (SBEQ) using a treadmill. MAIN OUTCOME MEASURES: Body weight, body composition, cardiorespiratory fitness, and exercise adherence. RESULTS: Of 148 subjects, 115 (78%) completed the 18-month program. At 18 months, mean (SD) weight loss was significantly greater in subjects in the SBEQ group compared with subjects in the SB group (-7.4 [7.8] kg vs -3.7 [6.6] kg; P<.05). Mean (SD) weight loss for subjects in the LB group (-5.8 [7.1] kg) was not significantly different than for subjects in the SB or SBEQ groups. Subjects in the SBEQ group maintained a higher level of exercise than subjects in both the SB and LB groups (P<.05) at 13 to 18 months of treatment. All groups showed an increase in cardiorespiratory fitness from baseline to 18 months, with no difference between groups. Mean (SD) weight loss at 18 months was significantly greater in individuals exercising more than 200 min/wk throughout the intervention (-13.1 [8.0] kg) compared with individuals exercising 150 to 200 min/wk (-8.5 [5.8] kg) or less than 150 min/wk (-3.5 [6.5] kg) (P<.05). CONCLUSIONS: Compared with the LB group, subjects in the SB group did not experience improved long-term weight loss, exercise participation, or cardiorespiratory fitness. Access to home exercise equipment facilitated the maintenance of SB, which may improve long-term weight loss. A dose-response relationship exists between amount of exercise and long-term weight loss in overweight adult women.

Adult↗
PubMed2000

Heart rate recovery and treadmill exercise score as predictors of mortality in patients referred for exercise ECG.

CONTEXT: Both attenuated heart rate recovery following exercise and the Duke treadmill exercise score have been demonstrated to be independent predictors of mortality, but their prognostic value relative to each other has not been studied. OBJECTIVE: To assess the associations among abnormal heart rate recovery, treadmill exercise score, and death in patients referred specifically for exercise electrocardiography. DESIGN AND SETTING: Prospective cohort study conducted in an academic medical center between September 1990 and December 1997, with a median follow-up of 5.2 years. PATIENTS: A total of 9454 consecutive patients (mean [SD] age, 53 [11] years; 78% male) who underwent symptom-limited exercise electrocardiographic testing. Exclusion criteria included age younger than 30 years, history of heart failure or valvular disease, pacemaker implantation, and uninterpretable electrocardiograms. MAIN OUTCOME MEASURES: All-cause mortality, as predicted by abnormal heart rate recovery, defined as failure of heart rate to decrease by more than 12/min during the first minute after peak exercise, and by treadmill exercise score, defined as (exercise time) - (5 x maximum ST-segment deviation) - (4 x treadmill angina index). RESULTS: Three hundred twelve deaths occurred in the cohort. Abnormal heart rate recovery and intermediate- or high-risk treadmill exercise score were present in 20% (n = 1852) and 21% (n = 1996) of patients, respectively. In univariate analyses, death was predicted by both abnormal heart rate recovery (8% vs 2% in patients with normal heart rate recovery; hazard ratio [HR], 4.16; 95% confidence interval [CI], 3.33-5.19; chi(2) = 158; P<.001) and intermediate- or high-risk treadmill exercise score (8% vs 2% in patients with low-risk scores; HR, 4.28; 95% CI, 3.43-5.35; chi(2) = 164; P<.001). After adjusting for age, sex, standard cardiovascular risk factors, medication use, and other potential confounders, abnormal heart rate recovery remained predictive of death (among the 8549 patients not taking beta-blockers, adjusted HR, 2.13; 95% CI, 1.63-2.78; P<.001), as did intermediate- or high-risk treadmill exercise score (adjusted HR, 1. 49; 95% CI, 1.15-1.92; P =.002). There was no interaction between these 2 predictors. CONCLUSIONS: In this cohort of patients referred specifically for exercise electrocardiography, both abnormal heart rate recovery and treadmill exercise score were independent predictors of mortality. Heart rate recovery appears to provide additional prognostic information to the established treadmill exercise score and should be considered for routine incorporation into exercise test interpretation. JAMA. 2000;284:1392-1398.

Adult↗
PubMed1999

Influence of high-intensity exercise training on the ventilatory response to exercise in patients with reduced ventricular function.

BACKGROUND: Exercise training increases exercise capacity in patients with reduced ventricular function in part through improved skeletal muscle metabolism, but the effect training might have on abnormal ventilatory and gas exchange responses to exercise has not been clearly defined. METHODS: Twenty-five male patients with reduced ventricular function after a myocardial infarction were randomized to either a 2-month high-intensity residential exercise training program or to a control group. Before and after the study period, upright exercise testing was performed with measurements of ventilatory gas exchange, lactate, arterial blood gases, cardiac output, and pulmonary artery and wedge pressures. RESULTS: In the exercise group, peak VO2 and VO2 at the lactate threshold increased 29 and 39%, respectively, whereas no increases were observed among controls. Maximal cardiac output increased only in the exercise group (1.7 L x min(-1), P < 0.05), and no changes in rest or peak exercise pulmonary pressures were observed in either group. At baseline, modest inverse relationships were observed between pulmonary wedge pressure and peak VO2 both at rest (r = -0.56, P < 0.05) and peak exercise (r = -0.43, P < 0.05). Maximal VE/VCO2 was inversely related to maximal cardiac output (r = -0.72, P < 0.001). Training did not have a significant effect on these relationships. Training lowered VE/VO2, heart rate, and blood lactate levels at matched work rates throughout exercise and tended to lower maximal Vd/Vt. The slope of the relationship between VE and VCO2 was reduced after training in the exercise group (0.33 pre vs 0.27 post, P < 0.01), whereas control patients did not differ. CONCLUSIONS: Exercise training among patients with reduced left ventricular function results in a systematic improvement in the ventilatory response to exercise. Training increased maximal cardiac output, tended to lower Vd/Vt, and markedly improved the efficiency of ventilation. Peak VO2 and ventilatory responses to exercise were only modestly related to pulmonary vascular pressures, and training had no effect on the relationships between exercise capacity, ventilatory responses, and pulmonary pressures.

Anaerobic Threshold↗
PubMed2002

Influence of cool-down exercise on autonomic control of heart rate during recovery from dynamic exercise.

The recovery of post-exercise heart rate (HR) is enhanced by a procedure of cooling down; however, the mechanism of this facilitated reduction is unknown. To determine whether more cardiac vagal reactivation is associated with a decrease in HR following cool-down exercise, we examined high-frequency R-R interval variability (HF, 0.15-0.40 Hz), an index of cardiac vagal tone, in six young healthy male subjects with a comparison between sitting rest after 6 minutes of cool-down cycling at 20% peak oxygen uptake (VO2peak) and sitting complete rest, following 5 min of upright cycle exercise at 70% VO2peak. During the last minute of exercise, there was no difference in HR between the two exercise tests before performing or not performing cool-down exercise (mean +/- SE, 148.7 +/- 6.9 versus 149.7 +/- 7.0 beats/min, respectively, by a Wilcoxon signed-ranks test). After exercise, a similar initial rapid decrease in HR and subsequent decline was observed during the first 6 min of recovery, regardless of cool-down exercise. However, the resting HR average following cool-down exercise was significantly lower than the corresponding HR without cool-down exercise (92.1 +/- 3.0 versus 100.8 +/- 3.6 beats/min, P < 0.05). The corresponding HF amplitude was slightly, but significantly greater with than without cool-down exercise (10.6 +/- 2.2 versus 9.0 +/- 1.9, P < 0.05). Thus the increase in HF amplitude corresponded to a decrease in resting HR following cool-down exercise, as compared to complete rest without cool-down exercise. Therefore, we conclude that after moderate exercise, the decrease in resting HR following cool-down exercise is associated with an increase in cardiac vagal tone.

Adaptation, Physiological↗