Comparison of high- and low-intensity exercise training early after acute myocardial infarction

Association between exercise capacity and left ventricular geometry in overweight patients with mild systemic hypertension

The purpose of this study was to determine the relation between left ventricular (LV) geometry and exercise capacity in unmedicated, hypertensive patients. Analysis of the data revealed peak oxygen consumption (ml kg(-1) min(-1)) for concentric hypertrophy (corrected mean +/- SE 23.5 +/- 1.2) was significantly less (F = 3.68, p <0.02) than the concentric remodeling (28.1 +/- 1.2) and normal (27.3 +/- 0.6) geometries. The LV geometric pattern was found to be associated with exercise capacity in unmedicated, hypertensive patients, such that patients with concentric hypertrophy showed reduced capacity.

The beneficial effect of regular endurance exercise training on blood pressure and quality of life in patients with hypertension

Regular aerobic exercise can reduce blood pressure and is recommended as part of the lifestyle modification to reduce high blood pressure and cardiovascular risk. Hypertension itself, or/and pharmacological treatment for hypertension is associated with adverse effects on some aspects of quality of life. This study was performed to evaluate the effects of regular endurance exercise training on quality of life and blood pressure. Patients with mild to moderate hypertension (systolic blood pressure 140-180 or diastolic blood pressure 90-110 mm Hg) were randomized to a moderate-intensity aerobic exercise group training for 3 sessions/week over 10 weeks or to a non-exercising control group. Health-related quality of life was assessed with the Short Form 36-item Health Survey (SF-36) at baseline and after 6 and 10 weeks. In the 102 subjects (47 male, mean age 47 years) who completed the study, reductions in blood pressure in the exercise group at 10 weeks (-13.1/-6.3 mm Hg) were significant (P < 0.001) compared to baseline and to the control group (-1.5/+6.0 mm Hg). Unlike the control group, the exercise group showed an increase in exercise capacity from 8.2 +/- 1.6 to 10.8 +/- 2.2 METS (P < 0.01) and showed higher scores on 7 out of 8 subscales (P < 0.05) of the SF-36. Improvement in bodily pain and general health sub-scores correlated with reduction in systolic blood pressure. Regular endurance training improves both blood pressure and quality of life in hypertensive patients and should be encouraged more widely.

The effect of Tai Chi Chuan on the autonomic nervous modulation in older persons

PURPOSE

This study evaluated the effect of Tai Chi Chuan (TCC) on the autonomic nervous modulation in older persons.

METHODS

Twenty TCC practitioners and 20 normal controls were included in this study. The stationary state spectral heart rate variability (HRV) measures between TCC practitioners and normal controls, and the sequential changes in HRV measures after classical Yang's TCC were compared.

RESULTS

The total power, very low-frequency power, low-frequency power, normalized low-frequency power, and low-/high-frequency power ratios in TCC practitioners were all significantly higher than those of normal controls, whereas the heart rate and systolic and diastolic blood pressures were not different between these two groups of subjects. After TCC, the normalized high-frequency power increased significantly from 22.8 +/- 14.6 normalized units (nu) before TCC to 28.2 +/- 16.1 nu 30 min after TCC and to 30.6 +/- 18.4 nu 60 min after TCC. In contrast, the low-/high-frequency power ratio decreased significantly from 2.5 +/- 2.4 before TCC to 1.8 +/- 1.4 30 min after TCC and to 2.2 +/- 2.9 60 min after TCC. The heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, and pulse pressure also decreased sequentially after TCC.

CONCLUSION

The short-term effect of TCC was to enhance the vagal modulation and tilt the sympathovagal balance toward deceased sympathetic modulation in older persons. TCC might be good health-promoting calisthenics for older persons.

Relationship between exercise systolic blood pressure and left ventricular geometry in overweight, mildly hypertensive patients

OBJECTIVE

To examine the association between the graded exercise systolic blood pressure (SBP) response and left ventricular (LV) geometric structure in patients with untreated mild hypertension.

PARTICIPANTS

The study included 80 sedentary, overweight patients (43 female and 37 male) with unmedicated high normal blood pressure or stage 1-2 hypertension.

METHODS

An echocardiogram was used to determine LV mass and the relative wall thickness (RWT) in relation to the chamber dimension. Participants performed a maximal graded exercise test, and the SBP was recorded at workloads of 2, 4 and 6 metabolic equivalents and at peak exercise. Separate statistical models were used to determine the influence of LV mass indexed for height(2.7) (LVMIh) and RWT on submaximal exercise SBP and peak exercise SBP, controlling for resting SBP, age, gender, ethnicity and body mass index.

RESULTS

A greater RWT was associated with a higher submaximal SBP level (P = 0.038). Neither LVMIh (P = 0.989) nor the interaction of RWT and LVMIh (P = 0.787) were related to the submaximal SBP. None of the main or interaction effects of RWT and LVMIh were associated with the peak exercise SBP level.

CONCLUSION

Increases in RWT were associated with higher submaximal exercise SBP responses in a sample of overweight, unmedicated hypertensives. These results suggest that RWT is an important determinant of the association between cardiac mass and exercise SBP response.

Exercise training in women with heart disease: influence of hormone replacement therapy

PURPOSE

To examine the central and peripheral cardiovascular effects of exercise training in postmenopausal women with CAD with and without hormone replacement therapy (HRT and N-HRT).

METHODS

Thirty-eight female cardiac patients referred for cardiac rehabilitation were divided into HRT ( N= 18) or N-HRT (N = 20) groups. Peak oxygen uptake (VO2) peak and ventilatory anaerobic thresholds (AT) were determined, in addition to submaximal cardiac output (Q). Peripheral measures of resting and peak ischemic blood flows (BF) were also measured. Measurements were all repeated after 12 and 26 wk of exercise training consisting of 1 h of walking at 75-80% of the measured VO2peak at baseline (T1) for 5 d.wk(-1).

RESULTS

VO2peak mL.kg(-1).min(-1) at baseline (14.9 +/- 0.4) increased by 5% after 12 wk (15.6 +/- 0.4) and significantly by 15% (17.2 +/- 0.5) after 26 wk of exercise training (P < 0.001). The HRT group was significantly younger than the N-HRT group (58 vs 65 yr; P < 0.01) and had significantly higher VO2peaks at baseline (15.7 vs 14.2 mL.kg(-1).min(-1); P < 0.05), yet either did not influence changes in other variables. At fixed submaximal work rates, there was a significant training bradycardia ( P < 0.01), but insignificant changes in Q or stroke volume regardless of HRT status. Resting and peak ischemic calf BF and vascular conductance increased significantly ( P < 0.001) at 12 and 26 wk, with no difference found according to HRT status.

CONCLUSIONS

The cardiovascular responses to training in postmenopausal women with CAD appear to be consistent regardless of HRT status and dominated by peripheral adaptations.

Is brisk walking an adequate aerobic training stimulus for cardiac patients?

Walking is the most common aerobic training modality utilized in cardiac rehabilitation programs. However, it remains unclear whether or not brisk walking is of a sufficient intensity to improve aerobic fitness in this population. In this study, we investigated whether men and women with coronary artery disease can achieve an exercise intensity that is sufficient to induce a training effect, ie, a training heart rate (THR), defined as >/= 70% of measured maximal heart rate (HRmax), via brisk walking on a flat surface. One hundred forty-two outpatient volunteers from the William Beaumont Hospital Cardiac Rehabilitation Program (Royal Oak, MI) and the University of Wisconsin-La Crosse Exercise and Health Program (La Crosse, WI) were asked to walk one mile as briskly as possible on measured tracks. Heart rate was monitored throughout the walk via radiotelemetry. The percentage of patients within each gender and phase of rehabilitation who attained a THR were assessed using peak or symptom-limited exercise testing to determine the HRmax. All of the women and 90% of the men achieved a THR, averaging 85 +/- 8% and 79 +/- 10% of HRmax, respectively (mean +/- SD). There was no difference in the percentage of phase II or phase III cardiac rehabilitation program patients who achieved a THR. These findings suggest that brisk walking is of a sufficient intensity to elicit a THR in all but the most highly fit patients with coronary disease. Thus, physicians and allied health professionals can prescribe brisk walking on a flat surface to their cardiac patients with confidence that this intensity will achieve cardiorespiratory and health benefits.

Is there a threshold intensity for aerobic training in cardiac patients?

PURPOSE

Recent guidelines have recommended the use of a percentage of oxygen uptake reserve (VO2R) for prescribing aerobic exercise intensity for cardiac patients. Moreover, these guidelines suggest that a threshold intensity may exist, below which no improvement in peak oxygen uptake (VO2peak) occurs. The purpose, therefore, was to translate the intensity of aerobic exercise in previous training studies using cardiac patients into %VO2R units, and determine whether a threshold intensity exists.

METHODS

Twenty-three studies, using 28 groups of aerobically trained cardiac patients, were identified in which VO2peak was measured before and after training by gas exchange. Intensity of exercise was variously described as a percentage of VO2peak, percentage of peak heart rate (HRpeak), percentage of heart rate reserve (HRR), or percentage of peak workload. These intensities were translated into equivalent units of %VO2R.

RESULTS

Of the 28 groups of patients, three failed to show significant improvements in VO2peak. These groups exercised at intensities corresponding to 47-55% of VO2R. However, six other groups exercised at comparable intensities (i.e., 42% to 55% of VO2R) and experienced significant increases in VO2peak. Other confounding variables in these studies were similar, including the initial VO2peak of the subjects, suggesting that the failure of three groups to significantly improve aerobic capacity was due to their small sample size.

CONCLUSION

No threshold intensity for aerobic training was identified in cardiac patients, with the lowest intensity studied being approximately 45% of VO2R. It is possible that intensities below this value may be an effective training stimulus, especially in extremely deconditioned subjects, but further research is needed to test that possibility and to determine whether a threshold exists.

Beneficial effects on blood pressure and lipid profile of programmed exercise training in subjects with white coat hypertension

BACKGROUND

Patients with white coat hypertension comprise a substantial portion of the hypertensive population. Previous reports have shown that moderate-intensity regular exercise training in patients with mild hypertension usually reduces blood pressure (BP), but there is a lack of data regarding individuals with white coat hypertension. This study was performed to evaluate whether programmed exercise was effective in reducing BP in patients with white coat hypertension and whether it also had beneficial effects on other biochemical parameters.

METHODS

A total of 42 patients (23 men and 19 women) with white coat hypertension (mean 24-h ambulatory BP 119.2 +/- 6.6/78.3 +/- 5.8 mm Hg) were divided randomly into two groups: control (n = 20) (no exercise), and moderate-intensity exercise (n = 22). The training group exercised three times per week at the prescribed exercise intensity using a treadmill exercise program. Blood pressure, heart rate, and biochemical parameters were monitored every 4 weeks for 12 weeks.

RESULTS

Significant reductions in clinic and ambulatory BPs were seen in the exercise group after only 4 weeks regular exercise training and these persisted over the 12-week study. The mean maximal reductions in clinic BP were 11 mm Hg for systolic and 5 mm Hg for diastolic pressure. Significant reductions were found in plasma total cholesterol (-6.1%), low-density lipoprotein cholesterol (LDL-C) (-14.1%), and triglyceride (-11.4%). Elevation of high-density lipoprotein cholesterol (HDL-C) (+11.2%) was also noted.

CONCLUSIONS

These data, which are clinically significant, suggest that 12 weeks of exercise training can result in successful reduction of BP and favorable changes in the lipid profile that would be beneficial to patients with white coat hypertension.

Blood lipid and lipoprotein adaptations to exercise: a quantitative analysis

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favourably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met. The thresholds established from cross-sectional literature occur at training volumes of 24 to 32 km (15 to 20 miles) per week of brisk walking or jogging and elicit between 1200 to 2200 kcal/wk. This range of weekly energy expenditure is associated with 2 to 3 mg/dl increases in high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) reductions of 8 to 20 mg/dl. Evidence from cross-sectional studies indicates that greater changes in HDL-C levels can be expected with additional increases in exercise training volume. HDL-C and TG changes are often observed after training regimens requiring energy expenditures similar to those characterised from cross-sectional data. Training programmes that elicit 1200 to 2200 kcal/wk in exercise are often effective at elevating HDL-C levels from 2 to 8 mg/dl, and lowering TG levels by 5 to 38 mg/dl. Exercise training seldom alters total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C). However, this range of weekly exercise energy expenditure is also associated with TC and LDL-C reductions when they are reported. The frequency and extent to which most of these lipid changes are reported are similar in both genders, with the exception of TG. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with weekly energy expenditures of 1200 to 2200 kcal/wk. It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. This amount of physical activity, performed at moderate intensities, is reasonable and attainable for most individuals and is within the American College of Sports Medicine's currently recommended range for healthy adults.

VO(2) reserve and the minimal intensity for improving cardiorespiratory fitness

PURPOSE

The American College of Sports Medicine has stated that aerobic training needs to occur at a minimum threshold intensity of 50% VO(2max) for most healthy adults and at 40% VO(2max) for those with a very low initial fitness. Recently, the concept of VO(2) reserve (%VO(2R), i.e., a percentage of the difference between maximum and resting VO(2)) has been introduced for prescribing exercise intensity. This analysis was designed to determine the threshold intensity for improving cardiorespiratory fitness expressed as %VO(2R) units.

METHODS

Previous studies in healthy subjects (N = 18) that evaluated the results of training at low-to-moderate intensities (i.e., < or = 60% VO(2max)) were identified. The original studies described the intensity of exercise variously as %VO(2max), %HRR, %HR(max), or as a specific HR value. In each case, the intensity was translated into %VO(2R) units.

RESULTS

Exercise training intensities below approximately 45% VO(2R) were consistently ineffective at increasing VO(2max) in studies that used subjects with mean initial VO(2max) values > 40 mL x min(-1) x kg(-1). In studies using subjects with mean initial VO(2max) values < 40 mL x min(-1) x kg(-1), no intensity was found to be ineffective. For this latter group of subjects, the lowest intensities examined were approximately 30% VO(2R).

CONCLUSION

Although evidence for a threshold intensity was not strong, this analysis of training studies supports the use of 45% VO(2R) as a minimal effective training intensity for higher fit subjects and 30% VO(2R) for lower fit subjects.

Absolute versus relative intensity of physical activity in a dose-response context

PURPOSE

To examine the importance of relative versus absolute intensities of physical activity in the context of population health.

METHODS

A standard computer-search of the literature was supplemented by review of extensive personal files.

RESULTS

Consensus reports (Category D Evidence) have commonly recommended moderate rather than hard physical activity in the context of population health. Much of the available literature provides Category C Evidence. It has often confounded issues of relative intensity with absolute intensity or total weekly dose of exercise. In terms of cardiovascular health, there is some evidence for a threshold intensity of effort, perhaps as high as 6 METs, in addition to a minimum volume of physical activity. Decreases in blood pressure and prevention of stroke seem best achieved by moderate rather than high relative intensities of physical activity. Many aspects of metabolic health depend on the total volume of activity; moderate relative intensities of effort are more effective in mobilizing body fat, but harder relative intensities may help to increase energy expenditures postexercise. Hard relative intensities seem needed to augment bone density, but this may reflect an associated increase in volume of activity. Hard relative intensities of exercise induce a transient immunosuppression. The optimal intensity of effort, relative or absolute, for protection against various types of cancer remains unresolved. Acute effects of exercise on mood state also require further study; long-term benefits seem associated with a moderate rather than a hard relative intensity of effort.

CONCLUSIONS

The importance of relative versus absolute intensity of effort depends on the desired health outcome, and many issues remain to be resolved. Progress will depend on more precise epidemiological methods of assessing energy expenditures and studies that equate total energy expenditures between differing relative intensities. There is a need to focus on gains in quality-adjusted life expectancy.

Iodine-123 MIBG imaging before treatment of heart failure with carvedilol to predict improvement of left ventricular function and exercise capacity

BACKGROUND

We examined whether cardiac sympathetic imaging with iodine-123 metaiodobenzylguanidine (MIBG) would predict improvement of left ventricular (LV) function and exercise capacity in patients with heart failure after treatment with carvedilol.

METHODS AND RESULTS

Eighteen patients with heart failure and 5 control subjects underwent I-123 MIBG imaging. Heart-to-mediastinum ratios at 20 minutes and 3 hours and myocardial washout rates (WR) were measured. Of the 18 patients, 11 were randomized to receive carvedilol medication, whereas the remaining 7 received a placebo. Only the carvedilol group demonstrated a significant improvement in both heart failure functional class and LV ejection fraction (EF) 1 year after the start of medication. Within the carvedilol group, MIBG WR showed a significant inverse correlation with improvement in LVEF (rho = -0.74, P =.02). The diagnostic accuracy of WR for predicting EF response to carvedilol was 91%. WR also appeared to be inversely related to the peak oxygen consumption rate (rho = -0.65, P =.08), although this did not reach statistical significance.

CONCLUSION

I-123 MIBG imaging appears useful in predicting which patients with heart failure are likely to show the most improvement in LV function and exercise capacity after carvedilol treatment. Further studies in this area appear to be warranted.

Differential effects of high-frequency versus low-frequency exercise training in rehabilitation of patients with coronary artery disease

OBJECTIVES

We sought to study the influence of frequency of exercise training during cardiac rehabilitation on functional capacity (i.e., peak oxygen consumption [VO2] and ventilatory anaerobic threshold [VAT]) and quality of life (QoL).

BACKGROUND

Although the value of cardiac rehabilitation is now well established, the influence of the different program characteristics on outcome has received little attention, and the effect of frequency of exercise training is unclear. Functional capacity is regularly evaluated by peak VO2 but parameters of submaximal exercise capacity such as VAT should also be considered because submaximal exercise capacity is especially important in daily living.

METHODS

Patients with coronary artery disease (n = 130, 114 men; mean age 52 +/- 9 years) were randomized to either a high- or low-frequency program of six weeks (10 or 2 exercise sessions per week of 2 h, respectively). Functional capacity and QoL were assessed before and after cardiac rehabilitation. Global costs were also compared.

RESULTS

Compared with baseline, mean exercise capacity increased in both programs: for high- and low-frequency, respectively: peak VO2 = 15% and 12%, Wmax = 18% and 12%, VAT = 35% and 12% (all p < 0.001). However, when the programs were compared, only VAT increased significantly more during the high-frequency program (p = 0.002). During the high-frequency program, QoL increased slightly more, and more individuals improved in subjective physical functioning (p = 0.014). We observed superiority of the high-frequency program, especially in younger patients. Mean costs were estimated at 4,455 and 2,273 Euro, respectively, for the high- and low-frequency programs.

CONCLUSIONS

High-frequency exercise training is more effective in terms of VAT and QoL, but peak VO2 improves equally in both programs. Younger patients seem to benefit more from the high-frequency training.

The effect of Tai Chi on cardiorespiratory function in patients with coronary artery bypass surgery

PURPOSE

This study prospectively evaluated the training effect of a 1-yr Tai Chi Chuan (TCC) program for low-risk patients with coronary artery bypass surgery (CABS) after a postoperative outpatient (phase II) cardiac rehabilitation program.

METHODS

Twenty patients with mean age of 56.5+/-7.4 yr completed this study. The TCC group included nine men who practiced classical Yang TCC with an exercise intensity of 48-57% heart rate range (HRR). The control group included 11 men whom were recommended to do a home-based self-adjusted exercise program with similar intensity of phase II cardiac rehabilitation. Graded exercise tests were performed before and after 1 yr of training for all subjects.

RESULTS

Mean attendance of the TCC group was 3.8+/-1.5 times weekly in contrast to 1.7+/-1.1 times for the control group. During the follow-up examination, the TCC group increased 10.3% in VO2peak (from 26.2+/-4.4 to 28.9+/-5.0 mL x kg(-1) min(-1), P<0.01) and increased 11.9% in peak work rate (from 135+/-26 W to 151+/-28 W, P<0.01). However, the control group showed slight decrease in VO2peak from 26.0+/-3.9 to 25.6+/-4.6 mL x kg(-1) x min(-1) and in peak work rate from 131+/-23 W to 128+/-32 W. At the ventilatory threshold, the TCC group also showed significant increase in VO2 and work rate (P<0.05). The control group did not significantly change in these variables.

CONCLUSIONS

The study demonstrated that a 1-yr TCC program for low-risk patients with CABS could favorably enhance cardiorespiratory function.

Predicting peak oxygen uptake among older patients with chronic illness

PURPOSE

To compare three equations developed to predict VO2 among patients diagnosed with one of two chronic diseases: essential hypertension (HTN), and fibromyalgia (FM). The equations included the American College of Sports Medicine (ACSM) equation, the FAST equation developed from the Fitness and Arthritis in Seniors Trial (FAST), and an equation developed by Foster et al.

METHODS

One hundred twenty-two HTN subjects and 68 FM subjects completed a maximum exercise test according to the Duke/Wake Forest protocol. Measured peak VO2 was then compared with the VO2 predicted by the ACSM, FAST and FOSTER equations, using several statistical methods.

RESULTS

The ACSM equation overpredicted peak VO2 in the HTN group by 10.0 +/- 4.0 mL/kg-1/min-1, and in the FM group by 8.6 +/- 4.9 mL/kg-1/min-1 (P < 0.0001). The FAST equation, however, underestimated peak VO2 by 1.5 +/- 4.2 mL/kg-1/min-1 (P < 0.01) and 1.0 +/- 3.3 mL/kg-1/min-1 (P < 0.0001) in the HTN and FM groups, respectively. The FOSTER equation overestimated peak VO2 by 2.3 +/- 3.6 mL/kg-1/min-1 in the HTN group and by 2.1 +/- 3.5 mL/kg-1/min-1 in the FM group (P < 0.0001). A large degree of variability was found for each of the equations.

CONCLUSION

Results of this investigation indicate that all three equations produced peak VO2 values that were statistically different from measured values. Although the ACSM equation overestimated VO2 by more than 2 metabolic equivalents (METs) in each patient group, both the FAST and FOSTER equations produced differences that were less than 1 MET. Further research is needed to examine the FAST and FOSTER equations among other patient populations and with other exercise protocols.

Contemporary cardiac rehabilitation services

Major changes will be required in the components and delivery of cardiac rehabilitation services in the era of managed care. These include restructuring and amplifying the coronary risk reduction services that are currently provided, and offering group and home-based cardiac rehabilitation services to increase their availability.

Comparison of standard- and extended-length participation in cardiac rehabilitation on body composition, functional capacity, and blood lipids

Participation in a standard-length outpatient cardiac rehabilitation program (CRP) for 3 months is known to result in positive changes in body composition, functional capacity, and blood lipids in patients with coronary artery disease. However, there has been little attempt to compare patients who remain active in a formal CRP for an extended length of >1 year with patients who exit after a standard length of 3 months. Consequently, 50 patients underwent a series of tests including a maximal graded exercise treadmill test, assessment of body composition, and fasting blood lipid analysis, at entry to CRP and after a follow-up period that ranged from 1 to 5 years. All patients participated in a standard multidisciplinary cardiac rehabilitation program for 3 months. Twenty-five patients discontinued participation after 3 months and received no other contact from the program staff until follow-up, whereas 25 patients remained active in the program until follow-up. After statistically adjusting for baseline differences between the groups, significant differences were observed between the extended- and standard-length groups at follow-up for body weight (177 vs 183 lbs), percent fat (22% vs 24%), METS (10.5 vs 8.4), high-density lipoprotein level cholesterol (44 vs 39 mg/dl), total cholesterol/high-density lipoprotein ratio (5.2 vs 6.1), and triglycerides (134 vs 204 mg/dl), respectively. No significant differences in the adjusted means were observed between the groups at follow-up for total cholesterol (209 vs 219 mg/dl) and low-density lipoprotein cholesterol (136 vs 138 mg/dl). Data from this study demonstrate the efficacy of extended participation in CRP on body composition, functional capacity, and blood lipids. Greater efforts need to be directed at retaining patients in low-cost, center-based maintenance programs and at extending monitoring of patients exiting standard length CRPs.

Assessment of a circuit of exercises through heart rate response

OBJECTIVE

A circuit of seven exercises was designed for a cardiac population. This study evaluated whether the patients achieved their training heart rate during the circuit, recommended to be 70-85% of the maximum heart rate achieved during an exercise test.

DESIGN

Patients were randomly allocated to a starting exercise to balance any order effect from performing the exercises in a given sequence. Each of the seven exercises was performed for 30 s, so one circuit lasted 3.5 min. The circuit was repeated five times.

PATIENTS

Twenty patients who had had myocardial infarctions within 6 weeks of the study participated.

OUTCOME

Heart rate was measured to assess the stress placed on the cardiorespiratory system during the circuit. Measurements were taken at 10 and 20 s following the termination of each exercise and over two repetitions of the circuit (a total of 14 exercise periods).

RESULTS AND CONCLUSION

Comparisons of the readings taken at 10 and 20 s indicated, contrary to previously published findings, that no significant heart rate deceleration occurred within this period. Every exercise maintained the mean heart rate within the specified band of 70-85% of the maximum heart rate achieved during the exercise test. The study has shown that the selected exercises were suitable for use during a cardiac rehabilitation programme.

Contribution of job strain, job status and marital status to laboratory and ambulatory blood pressure in patients with mild hypertension

The effects of job strain, occupational status, and marital status on blood pressure were evaluated in 99 men and women with mild hypertension. Blood pressure was measured during daily life at home and at work over 15 h of ambulatory blood pressure monitoring. On a separate day, blood pressure was measured in the laboratory during mental stress testing. As expected, during daily life, blood pressure was higher at work than at home. High job strain was associated with elevated systolic blood pressure among women, but not men. However, both men and women with high status occupations had significantly higher blood pressures during daily life and during laboratory mental stress testing. This was especially true for men, in that men with high job status had higher systolic blood pressures than low job status men. Marital status also was an important moderating variable, particularly for women, with married women having higher ambulatory blood pressures than single women. During mental stress testing, married persons had higher systolic blood pressures than unmarried individuals. These data suggest that occupational status and marital status may contribute even more than job strain to variations in blood pressure during daily life and laboratory testing.

Response of patients with coronary artery disease stratified by ejection fraction following short-term training

The purpose of this study was to investigate the response of patients with ischemic heart disease and varied left ventricular function following 6 weeks of exercise training. We studied the oxygen consumption (VO2), and central hemodynamic and metabolic responses of 14 patients with coronary artery disease (CAD) stratified by left ventricular ejection fraction (EF). There were two groups of patients: normal EF (NEF), EF = 64 +/- 9.9 (mean +/- S.E.M.); n = 7, and diminished EF (DEF), EF = 36 +/- 11.6; n = 7. The patients ranged in age from 42 to 72 years (54.9 +/- 2.2), and were evaluated prior to and then following training. Measures of VO2, cardiac output (Qt) stroke volume (SV), heart rate (HR), exercise duration (XTIME) and intensity (XI), as well as plasma lactate (LA), and the catecholamines epinephrine (E) and norepinephrine (NE) were obtained in response to maximal cycle ergometry. Subjects trained three times per week, 30 min per session, at an intensity equal to 70% of their peak oxygen consumption. Repeated measures analysis of variance (ANOVA) revealed no interaction between groups suggesting a similar training response. Significant post-training changes (P < 0.05) were observed in peak VO2 (VO2peak) NEF, 11.8% increase, (16.0 +/- 1.3 to 17.9 +/- 1.1 ml/kg/min) and DEF, 9.3% increase (15.1 +/- 1.6 to 16.5 +/- 1.2 ml/kg/min); submaximal HR, 4% decrease in the NEF (95.57 +/- 4.58 to 92 +/- 4.43 beats/min) and a 6% decrease in the DEF (107.29 +/- 7.44 to 101.43 +/- 6.77 beats/min); XTIME NEF, 11.2% increase (7.8 +/- 0.57 to 8.67 +/- 0.61 min) and DEF, 16.6% increase (7.3 +/- 0.91 to 8.51 +/- 0.69 min); and XI NEF, 19.2% increase (104.3 +/- 11.3 to 124.3 +/- 12.9 W) DEF, 21.2% increase (94.3 +/- 18.5 to 114.3 +/- 16.9 W), and a 15% decrease in resting NE (350 +/- 26 to 296.9 +/- 19 pg/ml). There were no changes in Qt, SV, LA, E, peak NE or peak HR for either group. These findings suggest short-term endurance training at 70% VO2peak provide the necessary stimulus for individuals with CAD and NEF or DEF to display an improvement in XI, XTIME, and VO2peak. The lack of a significant enhancement in Qt with short-term training may indicate that the mechanism by which both study groups were able to attain significantly higher levels of VO2peak may have been attributable to peripheral mechanisms rather than any alterations in Qt, a central mechanism.

Early programmes of high and low intensity exercise and quality of life after acute myocardial infarction

OBJECTIVE

To determine whether a group programme of light exercise could improve quality of life in patients after acute myocardial infarction to the same extent as a high intensity exercise training programme.

SETTING

Australian teaching hospital.

PATIENTS

224 men from a consecutive series of 339 men under 70 admitted to a coronary care unit with transmural acute myocardial infarction.

INTERVENTION

Patients were randomly allocated in hospital to a group programme lasting eight weeks of either high intensity exercise training or light exercise.

MAIN OUTCOME MEASURES

Physical working capacity based on metabolic equivalents achieved from treadmill exercise tests at entry, after 11 weeks, and after one year. Quality of life based on self report scores of anxiety, depression, denial, and wellbeing and interview assessments of activities and psychosocial adjustment at entry, after four months, and after one year.

RESULTS

The two groups were well matched at entry. At 11 weeks the mean results of treadmill testing were 10.7 (95% confidence interval 10.20 to 11.20) metabolic equivalents for exercise training and 9.7 (9.26 to 10.14) for light exercise (t = 2.85, df = 181, p = 0.005). Apart from this small temporary benefit in mean physical working capacity, there were no significant differences between groups. Improvement in occupational adjustment score from baseline to four months was greater after exercise training than after light exercise, but at one year repeated measures analysis of variance showed no significant effects of treatment or interaction between treatment and time point.

CONCLUSION

The effects on quality of life of a low cost programme of light exercise are similar to those obtained from a high intensity exercise training programme.

Exercise and the heart. Good, benign, or evil?

The risks and benefits of regular aerobic exercise have been studied extensively. Because of the potential risks, we believe that sedentary persons over age 40 who have cardiac risk factors, as well as patients with coronary artery disease (CAD), should have a complete physical examination and probably an exercise electrocardiogram before starting a vigorous exercise program. In general, however, regular exercise has proven to be extra-ordinarily safe and the theoretical and proven benefits appear to greatly outweigh the risks in most people, including those with CAD, those with severe left ventricular dysfunction, and the elderly.

Evaluation of changes in standard electrocardiographic QRS waveforms recorded from activity-compatible proximal limb lead positions

Proximal limb lead positions are currently used for activity-compatible electrocardiographic monitoring of myocardial ischemia. Two previously described systems for alternate limb lead placement were studied in patients with and without QRS evidence of healed anterior or inferior myocardial infarction. An innovative method was used to simultaneously record 6 standard and 6 modified limb leads, and 3 standard and 3 modified precordial leads on a standard digital electrocardiograph. Both alternate lead placement systems showed rightward frontal plane axis shift and diminished Q-wave durations in lead aVF compared with those of their simultaneous standard controls. Furthermore, potential differences between the standard distal limb lead sites and 5 more proximal sites were explored along each limb. Differences along the left arm were accentuated relative to those along the right arm owing to differences in proximity of the arms to the myocardium. Along the lower limb, and anterior site showed less deviation from standard than did a more lateral site. It is imperative that recordings from alternate sites be labeled accordingly so that their output cannot be confused with that obtained from standard sites.

Effects of exercise training on cardiovascular function and plasma lipid, lipoprotein, and apolipoprotein concentrations in premenopausal and postmenopausal women

This study examined the effects of aerobic exercise on lipid levels in premenopausal and postmenopausal women. Fifty healthy middle-aged women (mean age, 50 years) were randomly assigned to 12 weeks of either aerobic exercise (walking and jogging) or nonaerobic strength exercise (circuit Nautilus training). Concentrations of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, and very low density lipoprotein cholesterol were assessed, along with apolipoprotein (apo) A-I, apo A-II, apo B, and triglycerides. To document changes in aerobic capacity, maximum treadmill testing was performed with expired-gas analysis before and after the exercise program. Aerobic exercise was associated with an 18% improvement in peak VO2. Women in the aerobic group had an increased VO2, from 26.7 to 31.4 ml/kg/min (p less than 0.0001), while the VO2 of the women in the strength training group did not change (25.8 ml/kg/min before and after). There were no differential changes in lipid levels because all subjects experienced slight reductions in high density lipoprotein cholesterol and total cholesterol and increases in apo A-I and the apo A-I to apo B ratio. There was a tendency for the aerobic group to exhibit lower levels of apo A-II and a greater apo A-I to apo A-II ratio, however. We conclude that premenopausal and postmenopausal women experience similar changes in aerobic capacity and lipid levels with exercise and that the short-term effects of aerobic and nonaerobic exercise on lipid profiles are generally comparable.

Effect of early programmes of high and low intensity exercise on physical performance after transmural acute myocardial infarction

Does a programme of light exercise training after acute myocardial infarction produce the same improvement in treadmill performance as aerobic exercise training? Three hundred and eight men from a consecutive series of 479 men with transmural (Q wave) acute myocardial infarction, admitted to a single coronary care unit, were randomly allocated to eight weeks of group aerobic exercise training or group light exercise. Groups were well matched for all characteristics other than site of infarction, which did not significantly affect results. Mean (SD) physical working capacity (metabolic equivalents) determined by treadmill testing at the start of the study (in the third week after infarction) was 6.8 (2.2) v 6.7 (2.5) METs, at the end (in the eleventh week after infarction) 10.8 (2.3) v 9.9 (2.4) METs, and at 12 month review 10.8 (2.4) v 10.7 (1.9) METs for the exercise training group and the light exercise group respectively. The difference of 0.9 METs at the end of the study was the only significant difference between groups. There were no significant intergroup differences at any stage in resting and maximal heart rate, resting and maximal systolic blood pressure, or rate-pressure product. Apart from a small temporarily greater physical working capacity, the physical benefits of aerobic exercise training were equally well achieved by group light exercise.

Physiological, psychological, and behavioral factors and white coat hypertension

Patients with hypertension in the clinic but not during daily activities ("white coat" hypertension) may be at lower risk of hypertensive morbidity and mortality than patients with hypertension in both settings ("persistent" hypertension). We hypothesized that the white coat phenomenon was due to greater blood pressure reactivity to the stress of a clinic visit and that, as a consequence, white coat hypertensive patients would display greater blood pressure reactivity to exercise and mental stress, as well as increased emotional reactivity and higher levels of anger, anxiety, or depression. We studied 89 patients with essential hypertension between 29 and 59 years old with ambulatory blood pressure monitoring, treadmill exercise testing with oxygen consumption measurement, mental stress testing (including mental arithmetic, public speaking, and video game tasks), and psychological testing (State-Trait Anxiety Scale, Cook-Medley Hostility Scale, Center for Epidemiologic Studies Depression Scale, emotional reactivity scale). We defined white coat hypertension as a mean ambulatory systolic blood pressure of 135 mm Hg or less and diastolic 85 mm Hg or less and persistent hypertension as a mean ambulatory systolic blood pressure of 140 mm Hg or more or diastolic 90 mm Hg or more. Forty-nine patients were classified as persistent hypertensives and 20 as white coat hypertensives. No significant differences were seen in demographic or clinical characteristics, fitness level, blood pressure response to exercise or mental stress, or psychological characteristics, except that white coat hypertensive patients had lower systolic blood pressures in the clinic and during exercise and greater variability of clinic diastolic blood pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular rehabilitation: status, 1990

Cardiovascular rehabilitation is defined as the process of development and maintenance of a desirable level of physical, social, and psychologic functioning after the onset of a cardiovascular illness. Patient education, counseling, nutritional guidance, and exercise training play prominent roles in the process of rehabilitation. Benefits from cardiac rehabilitation include improved exercise capacity and decreased symptoms of angina pectoris, dyspnea, claudication, and fatigue. Recent pooled data regarding exercise training after myocardial infarction demonstrated a 20 to 25% reduction in mortality and major cardiac events. Exercise training may result in an improvement in systemic oxygen transport, a reduction in the myocardial oxygen requirement for a given amount of external work, and a decrease in the extent of myocardial ischemia during physical activity. The efficacy of modification of risk factors in reducing the progression of coronary artery disease and future morbidity and mortality has been established. Herein we review the history, current practice and results, and future challenges of cardiovascular rehabilitation.

Aerobic exercise reduces levels of cardiovascular and sympathoadrenal responses to mental stress in subjects without prior evidence of myocardial ischemia

Thirty-seven healthy type A men (mean age 42 years) were randomly assigned to either an aerobic exercise training group or to a strength and flexibility training group. Before exercise, subjects underwent comprehensive physiologic and behavioral assessments, including graded exercise treadmill testing with direct measurement of oxygen consumption (VO2) and measurement of cardiovascular (heart rate, systolic and diastolic blood pressure and rate pressure product) and neuroendocrine (epinephrine and norepinephrine) responses to mental arithmetic. The aerobic exercise consisted of walking and jogging at an intensity of greater than or equal to 70% maximal heart rate reserve for 1 hour 3 times/week for 12 consecutive weeks. The strength training consisted of 1 hour of circuit Nautilus training 2 times/week for 12 weeks. At the completion of the exercise program, all subjects underwent repeat testing. For the aerobic group, peak VO2 increased significantly from 33.6 to 38.4 ml/kg/min (p less than 0.001), whereas the strength group only achieved a slight increase from 34.5 to 35.6 ml/kg/min (difference not significant). During the mental arithmetic, the aerobic group experienced a greater reduction in levels of heart rate, diastolic blood pressure and rate pressure product than the strength group (after completing the exercise training programs). The aerobic group also tended to secrete less epinephrine and to show a faster recovery than the strength group after the exercise program. In addition, the aerobic group tended to exhibit less cardiovascular reactivity to mental stress after exercise training. These data suggest that aerobic exercise reduces levels of cardiovascular and sympathoadrenal responses during and after mental stress.

An overview of randomized trials of rehabilitation with exercise after myocardial infarction

Of 22 randomized trials of rehabilitation with exercise after myocardial infarction (MI), one trial had results that achieved conventional statistical significance. To determine whether or not these studies, in the aggregate, show a significant benefit of rehabilitation after myocardial infarction, we performed an overview of all randomized trials, involving 4,554 patients; we evaluated total and cardiovascular mortality, sudden death, and fatal and nonfatal reinfarction. For each endpoint, we calculated an odds ratio (OR) and 95% confidence interval (95% CI) for the trials combined. After an average of 3 years of follow-up, the ORs were significantly lower in the rehabilitation than in the comparison group: specifically, total mortality (OR = 0.80 [0.66, 0.96]), cardiovascular mortality (OR = 0.78 [0.63, 0.96]), and fatal reinfarction (OR = 0.75 [0.59, 0.95]). The OR for sudden death was significantly lower in the rehabilitation than in the comparison group at 1 year (OR = 0.63 [0.41, 0.97]). The data were compatible with a benefit at 2 (OR = 0.76 [0.54, 1.06]) and 3 years (OR = 0.92 [0.69, 1.23]), but these findings were not statistically significant. For nonfatal reinfarction, there were no significant differences between the two groups after 1 (OR = 1.09 [0.76, 1.57]), 2 (OR = 1.10 [0.82, 1.47]), or 3 years (OR = 1.09 [0.88, 1.34]) of follow-up. The observed 20% reduction in overall mortality reflects a decreased risk of cardiovascular mortality and fatal reinfarction throughout at least 3 years and a reduction in sudden death during the 1st year after infarction and possibly for 2-3 years. With respect to the independent effects of the physical exercise component of cardiac rehabilitation, the relatively small number of "exercise only" trials, combined with the possibility that they may have had a formal or informal nonexercise component precludes the possibility of reaching any definitive conclusion. To do so would require a randomized trial of sufficient size to distinguish between no effect and the most plausible effect based on the results of this overview.

Exercise-related changes in serum catecholamines and potassium: effect of sustained exercise above and below lactate threshold

Plasma potassium and catecholamines exhibit rapid shifts during exercise testing, particularly when exercise intensity exceeds lactate threshold. To assess changes that may occur during sustained exercise, we studied 10 healthy men to determine the effect of 20 minutes of exercise at 25 W above lactate threshold (ALT) and 20 minutes of exercise at 25 W below lactate threshold (BLT). Both conditions showed elevation of catecholamines at end exercise compared to baseline, but catecholamine levels ALT were significantly higher than the levels BLT (2270 +/- 190 versus 900 +/- 230 pg/ml norepinephrine, p less than 0.001; 509 +/- 69 versus 150 +/- 18 pg/ml epinephrine, p less than 0.001). This difference persisted at 2 minutes of recovery (1620 +/- 130 versus 590 +/- 60 pg/ml norepinephrine, p less than 0.001; 216 +/- 31 versus 98 +/- 16 pg/ml epinephrine, p less than 0.001). Both conditions resulted in a significant elevation in potassium at end exercise compared to baseline, but the potassium levels ALT were significantly higher than the levels BLT (1.1 +/- 0.1 mEq/L versus 0.5 +/- 0.1 mEq/L, p less than 0.001. The fall in potassium in the immediate post-exercise period was significantly greater following exercise ALT (-0.8 +/- 0.1 mEq/L versus -0.2 +/- 0.1 mEq/L, p less than 0.001). Thus sustained exercise slightly ALT resulted in a significant potassium flux and very elevated catecholamine levels. Avoiding these metabolic stresses by exercising BLT may decrease chances for exercise-related arrhythmia or other cardiac dysfunction in susceptible patients.

Rehabilitation of the patient with coronary heart disease. New information for improved care

The benefits of early ambulation and predischarge exercise testing for stable patients after acute myocardial infarction have been well documented. Early exercise testing can help stratify patients into risk categories; these can guide recommendations for further diagnostic testing for medical or surgical interventions, as well as suggest appropriate activity levels after hospital discharge. The scope of cardiac patients currently considered eligible for exercise rehabilitation is far greater than in the past. Exercise training can improve functional capacity, predominantly mediated by peripheral adaptations; guidelines must be developed for the exercise training and surveillance of severely ill and elderly coronary patients. Education in coronary risk reduction and counseling to limit psychosocial complications of coronary disease and encourage return to work when appropriate can improve the coronary patient's functional status and clinical outcome. Further research is needed to determine the rehabilitative needs of more severely impaired, medically complex patient subgroups and the most cost-effective means of delivering rehabilitative services.

Invalidation of the resting electrocardiogram obtained via exercise electrode sites as a standard 12-lead recording

The difficulty in interpreting the standard 12-lead electrocardiogram (ECG) due to the interference from muscle potentials produced by arm and leg motion makes it unsuitable during the exercise treadmill test. Likewise, the exercise lead placement ECG cannot substitute for the standard ECG due to significant errors in the former's diagnostic interpretation. This study compares the ECGs recorded via standard and exercise sites regarding frontal and horizontal plane axes, diagnosis and location of myocardial infarction and estimation of infarct size using the complete 54-criteria and 32-point Selvester QRS scoring system. The altered limb lead locations on the exercise ECG caused the QRS vectors to artifactually appear to be directed more inferiorly, posteriorly and rightward, producing a marked rightward mean frontal plane axis shift of +48 degrees (p less than 0.00001). No false positive or false negative anterior infarct was seen on the exercise lead placement ECG, whereas inferior and posterior infarcts were lost in 69% and 31% of patients, respectively. A false lateral infarct was seen in 19% of patients. Estimation of infarct size differed between the 2 ECG sets, with 11 patients increasing their infarct size by 3 to 9% and 14 others decreasing it by 3 to 15% on the exercise lead placement ECG. This study demonstrates that use of body torso positions for limb leads results in substantial QRS waveform variations that disqualify the exercise lead placement ECG as a "standard" recording. Such ECGs should therefore be labeled as "torso positioned" or "nonstandard" to prevent misuse for clinical and investigative purposes.