Betsy E. Jensen

Exercise testing and training in physically disabled men with clinical evidence of coronary artery disease

Abstract A prospective, randomized, controlled clinical trial in patients with coronary artery disease (CAD) and a concurrent physical disability evaluated the effects of a home exercise training program on cardiovascular function and blood lipids. Eighty-eight men between the ages of 42 and 72 years (mean 62) with documented CAD and a physical disability with functional use of ≥2 etremities including 1 arm were randomized to either a 6-month home exercise training program using wheelchair ergometry or to a control group that received usual and customary care. Both groups received dietary instructions and were requested to follow a fat-controlled diet. Exercise test variables with echocardiography and blood lipids were measured at baseline and at 6 months. The home exercise training group significantly improved both peak exercise left ventricular ejection fraction (p = 0.007) and fractional shortening (p = 0.01) between baseline to 6 months, whereas the control group showed no significant changes. Exercise training effects of decreased resting heart rate (p = 0.03) and decreased peak rate pressure product (p = 0.03) were also found in the treatment group. No exercise-related cardiac complications occurred. Both groups significantly (p ≤ 0.01) increased high-density lipoprotein cholesterol levels. These results indicate that physically disabled men with CAD can safely participate in a home exercise training program which may result in intrinsic cardiac benefits. The metabolic cost of activities of daily living imposed on this disabled popu lation may also have a positive effect on high-density lipoprotein cholesterol levels.

Adherence in the training levels comparison trial.

In the Training Levels Comparison Trial, 197 male coronary heart disease patients were randomized to low or high intensity training with target heart rates, which corresponded to 50% and 85% of the VO2max achieved on the previous exercise test, respectively. Patients were to exercise at their assigned intensity level at three 1-h long supervised sessions per week for 2 yr. This paper reports on two components of adherence: attendance at exercise sessions and achievement of heart rates in the target range. During the first year of training, the average percent of exercise sessions attended (mean +/- SE) for the low intensity group (64.0 +/- 2.5%) was significantly higher than for the high intensity group (55.5% +/- 2.7%). At the end of 1 yr of training, 54% and 37% of the low and high intensity patients, respectively, achieved heart rates within 5 beats.min-1 of their target heart rates. Although the low intensity program was preferable to achieve maximum attendance, attenders on the high intensity program achieved higher heart rates. These results suggest that to maximize the achieved heart rate, it would be optimal to motivate a cardiac rehabilitation patient to train at the high intensity level for a prolonged period of time.

Efficacy of high-intensity exercise training on left ventricular ejection fraction in men with coronary artery disease (The Training Level Comparison Study)

The purpose of this study was to compare high- versus low-intensity exercise training on the change in echocardiographic left ventricular ejection fraction (LVEF) from rest to peak exercise. Sedentary men with coronary artery disease, aged 30 to 70 years, were randomized to dynamic exercise training of either low intensity, 50% of maximal oxygen consumption, n = 89; or high intensity, 85% of maximal oxygen consumption, n = 111. No other interventions were imposed and patients were evaluated at 6 months and 1 year. Both exercise groups significantly increased exercise capacity without adverse events, but the increase was greater (p = 0.02) in the high-intensity exercise group. The mean exercise test rest-peak LVEF in the high-intensity group rose from 6.20% at baseline to 6.54% in 6 months and to 6.73% at 12 months, while the low-intensity group showed no improvement at 6 months and a decrease at 12 months. Multivariate analyses revealed that treatment group (high versus low intensity) significantly contributed to the change in rest-peak LVEF. When the exercise groups were subdivided by initial baseline LVEF < or = 50% versus > 50%, those with the higher LVEF in the high-intensity group showed a greater (p = 0.05) increase in the rest-peak LVEF from baseline to 1 year. Over a 1-year period, exercise capacity improved in both exercise-intensity groups, but more so in the high-intensity group, with no adverse events. The high-intensity group, compared with the low-intensity, showed more improvement in the rest-peak LVEF, especially in those with a higher LVEF at baseline.

Training level comparison study. Effect of high and low intensity exercise on ventilatory threshold in men with coronary artery disease.

PURPOSE To determine whether exercise at low intensity (LO; 50% of peak VO2) or high intensity (HI; 85% of peak VO2) results in improvement of the ventilatory threshold (VT), 186 men with coronary artery disease (CAD) were enrolled in an exercise study for 1 year. METHODS A symptom-limited exercise test was performed at baseline and the heart rate corresponding to 50% and 85% of peak VO2 was determined. Subjects were randomized to LO or HI intensity exercise. Exercise sessions included 45 minutes of walking/jogging and/or stationary cycling at the appropriate target heart rate and were conducted 3 days per week. The exercise test was repeated at 3 and 6 months. Target heart rates were revised to adjust for training. RESULTS Both LO and HI resulted in improved VO2 at VT and peak. However, HI resulted in greater improvement than LO. CONCLUSION Among this population, both HI and LO improve the VO2 at VT and peak, but the improvement is greater with HI. The VT can be a useful adjunct to heart rate and peak oxygen uptake when prescribing exercise.

DESIGN OF THE TRAINING LEVELS COMPARISON TRIAL

The Training Levels Comparison (TLC) trial was a grant-supported, multicenter, randomized, controlled clinical trial designed to determine whether cardiac rehabilitation patients would benefit from supervised exercise for a prolonged period (2 years) and whether subjecting patients to a more vigorous exercise program than currently recommended would provide additional cardiac benefit. If high-intensity exercise does not enhance the cardiac benefit, then physical activity should be limited to low-intensity levels that are safer, easier to implement and more adaptable to a greater number of patients. Patients were randomly assigned to either a low-intensity or high-intensity training program. All patients were to attend three 1-hour supervised exercise sessions per week for a period of 2 years. Attendance at exercise sessions and adherence to assigned treatments were monitored throughout the study. Patients were evaluated for outcome measures at 3, 6, 12, and 24 months. This paper reports the study design and methodology for the TLC trial, and should be useful in providing methodologies to facilitate comparison of data from other studies with different levels of exercise as an intervention.

Exercise Testing and Training in Physically Disabled Men With Clinical Evidence of Coronary Artery Disease

A prospective, randomized, controlled clinical trial in patients with coronary artery disease (CAD) and a concurrent physical disability evaluated the effects of a home exercise training program on cardiovascular function and blood lipids. Eighty-eight men between the ages of 42 and 72 years (mean 62) with documented CAD and a physical disability with functional use of > or = 2 extremities including 1 arm were randomized to either a 6-month home exercise training program using wheelchair ergometry or to a control group that received usual and customary care. Both groups received dietary instructions and were requested to follow a fat-controlled diet. Exercise test variables with echocardiography and blood lipids were measured at baseline and at 6 months. The home exercise training group significantly improved both peak exercise left ventricular ejection fraction (p = 0.007) and fractional shortening (p = 0.01) between baseline to 6 months, whereas the control group showed no significant changes. Exercise training effects of decreased resting heart rate (p = 0.03) and decreased peak rate pressure product (p = 0.03) were also found in the treatment group. No exercise-related cardiac complications occurred. Both groups significantly (p < or = 0.01) increased high-density lipoprotein cholesterol levels. These results indicate that physically disabled men with CAD can safely participate in a home exercise training program which may result in intrinsic cardiac benefits. The metabolic cost of activities of daily living imposed on this disabled population may also have a positive effect on high-density lipoprotein cholesterol levels.