Effects of physical deconditioning after intense endurance training on left ventricular dimensions and stroke volume.

To determine the role of preload in maintaining the enhanced stroke volume of upright exercise-trained endurance athletes after deconditioning, six highly trained subjects undergoing upright and supine bicycle ergometry were characterized before and after 3, 8 and 12 weeks of inactivity that reduced oxygen uptake by 20%. During exercise, oxygen uptake, cardiac output by carbon dioxide rebreathing, cardiac dimensions by M-mode echocardiography, indirect arterial blood pressure and heart rate were studied simultaneously. Two months of inactivity resulted in a reduction in stroke volume, calculated as cardiac output/heart rate, during upright exercise (p less than 0.005) without a significant change during supine exercise. A concomitant decrease in the left ventricular end-diastolic dimension from the trained to the deconditioned state was observed in the upright posture (5.1 +/- 0.3 versus 4.6 +/- 0.3 cm; p = 0.02) but not with recumbency (5.4 +/- 0.2 versus 5.1 +/- 0.3 cm; p = NS). There was a strong correlation between left ventricular end-diastolic dimension and stroke volume (r greater than 0.80) in all subjects. No significant changes in percent fractional shortening or left ventricular end-systolic dimension occurred in either position after cessation of training. Estimated left ventricular mass was 20% lower after 3 and 8 weeks of inactivity than when the subjects were conditioned (p less than 0.05 for both). Thus, the endurance-trained state for upright exercise is associated with a greater stroke volume during upright exercise because of augmented preload. Despite many years of intense training, inactivity for only a few weeks results in loss of this adaptation in conjunction with regression of left ventricular hypertrophy.

The effect of 7 years of intense exercise training on patients with coronary artery disease.

The purpose of this study was to evaluate the effects of long-term exercise training on maximal aerobic exercise capacity, evidence of myocardial ischemia and plasma lipid-lipoprotein concentrations in patients with coronary artery disease. Nine men with coronary artery disease, aged 57 +/- 2 years, who had completed 12 months of supervised intense exercise training were restudied after 6 additional years during which they continued to exercise. The first 12 months of training resulted in a 44% increase in maximal oxygen consumption (VO2max) from 25.0 +/- 1.3 to 35.9 +/- 1.5 ml X kg-1 X min-1 (p less than 0.001). The VO2max after 6 additional years (total 7 years) of intense training was 36.8 +/- 2.4 ml X kg-1 X min-1. Plasma high density lipoprotein (HDL)-cholesterol concentration increased from 38 +/- 3 to 45 +/- 4 mg X dl-1 at 12 months and rose further to 53 +/- 5 mg X dl-1 at 6 years of follow-up (p less than 0.05). The atherogenic index (total cholesterol/HDL-cholesterol ratio) decreased from 5.8 +/- 0.4 to 4.9 +/- 0.4 by 12 months (p less than 0.01) and to 4.1 +/- 0.4 after 6 additional years of training (p less than 0.05). Although the maximal heart rate-pressure product was 14% higher after 12 months of training, maximal ST segment depression was significantly less, 0.27 +/- 0.06 versus 0.19 +/- 0.04 mV (p less than 0.05); this improvement was maintained after 6 years of additional training. These data provide evidence that the beneficial effects of a program of intense exercise training can be maintained for long periods in some motivated patients with coronary artery disease who continue to exercise.

Improvement in glucose tolerance after 1 wk of exercise in patients with mild NIDDM.

We investigated the effects of 1 wk of intense exercise on glucose tolerance in 10 men with abnormal glucose tolerance [7 had mild non-insulin-dependent diabetes mellitus (NIDDM), and 3 had impaired glucose tolerance]. The 7 days of exercise did not result in significant changes in body weight or maximal oxygen uptake. Plasma glucose concentration at 120 min averaged 227 +/- 23 mg/dl in an oral glucose tolerance test (OGTT) before and 170 +/- 18 mg/dl after the 7 days of exercise (P less than .001). There was a 36% reduction in the area under the glucose tolerance curve. Plasma insulin concentration at 120 min of the OGTT averaged 172 +/- 27 microU/ml before and 106 +/- 13 microU/ml after 7 days of exercise (P less than .001); the area under the insulin curve was decreased by 32%. In contrast to the response to 7 days of exercise, one bout of exercise did not result in an improvement in glucose tolerance. These results provide evidence that regularly performed, vigorous exercise can be effective in decreasing insulin resistance and improving glucose tolerance within 7 days in some patients with mild NIDDM.

Effects of exercise involving predominantly either joint-reaction or ground-reaction forces on bone mineral density in older women.

This study compared the effects of two exercise training programs, 11 months in duration, on bone mineral density (BMD) in older, sedentary women. Thirty-nine women, aged 60-74 years, were assigned to the following groups: (a) a group that performed exercises that introduced stress to the skeleton through ground-reaction forces (GRF) (i.e., walking, jogging, stairs); (b) a group that performed exercises that introduced stress to the skeleton through joint-reaction forces (JRF) (i.e., weight lifting, rowing); or (c) a no-exercise control group. BMD of the whole body, lumbar spine, proximal femur, and distal forearm was assessed five times at approximately 3-month intervals. The GRF and JRF exercise programs resulted in significant and similar increases in BMD of the whole body (2.0 +/- 0.8% and 1.6 +/- 0.4%, respectively), lumbar spine (1.8 +/- 0.7% and 1.5 +/- 0.5%, respectively), and Ward's triangle region of the proximal femur (6.1 +/- 1.5% and 5.1 +/- 2.1%, respectively). There was a significant in BMD of the femoral neck only in response to the GRF exercise program (GRF, 3.5 +/- 0.8%; JRF, -0.2 +/- 0.7%). There were no significant changes in BMD in control subjects. Among all exercisers, there was a significant inverse (r = -0.52, p < 0.01) relationship between increases in whole body BMD and reductions in fat mass, suggesting a dose response effect of exercise on bone mass. Although femoral neck BMD was responsive only to the GRF exercise program, some adaptations (i.e., increase in lean body mass and strength) that were specific to the JRF exercise program may be important in preventing osteoporotic fractures by reducing the risk for falls. It remains to be determined whether all of these benefits can be gained through a training program that combines the different types of exercises employed in this study.

Altered hemodynamics during exercise in older essential hypertensive subjects.

This study was designed to compare the resting and exercise hemodynamics of older adults with moderate hypertension with those of age-matched normotensive controls. Thirty-one hypertensive (20 men, 11 women; mean age, 63.9 +/- 2.8 years) and 28 normotensive subjects (15 men, 13 women; mean age, 62.6 +/- 2.4 years) were studied. There were no differences between the groups in terms of body weight, body composition, and maximal O2 consumption (VO2). At rest, there were no differences in VO2, cardiac output, stroke volume, or heart rate between the two groups, although systolic (158 +/- 13 vs 121 +/- 12 mm Hg) and diastolic blood pressures (94 +/- 7 vs 79 +/- 8 mm Hg) were higher in the hypertensive subjects. The hypertensive subjects' elevated blood pressure at rest was the result of a higher total peripheral resistance. During exercise, the hypertensive subjects had a lower cardiac output and stroke volume, no difference in heart rate and VO2, higher systolic, diastolic, and mean blood pressures, and a higher total peripheral resistance compared with their normotensive peers. The results indicate that older hypertensive persons have an altered cardiovascular response to exercise as compared with age-matched normotensive subjects. The responses also indicate that older essential hypertensive persons do not undergo excessive myocardial demands during exercise of the intensity usually prescribed in rehabilitation programs.

The metabolic and psychological effects of exercise training in hemodialysis patients.

The effect of exercise training on metabolic abnormalities and psychological function was assessed in seven hemodialysis patients. Their initial work capacity was low and improved after 8 months of training. Exercise was associated with a reduction in the dose of antihypertensive medications in four patients and a decrease in phosphate binder therapy in three patients. There was also a rise in hematocrit levels (% delta = 34 +/- 20%, P less than 0.03) and the hemoglobin concentration (% delta = 37 +/- 23%, P less than 0.05) of five males. Plasma glucose levels fell (-5 +/- 2%, P less than 0.05, n = 5) and the glucose disappearance rate improved (20 +/- 7%, P less than 0.02), while hyperinsulinism decreased (-36 +/- 20%, P less than 0.02, n = 5) during training. There was no change in body weight or diet. Exercise lowered plasma triglyceride levels (-41 +/- 28%, P less than 0.02, n = 6) and raised the high-density lipoprotein cholesterol concentration (20 +/- 21%, P less than 0.05, n = 6). Psychological testing (n = 4) demonstrated that exercise training was associated with an improvement in depression, hostility, anxiety, social interaction, and outlook for the future. These results suggest that exercise can improve some of metabolic abnormalities and psychological dysfunction which exists in some dialysis patients.

Altered adaptive responses to training by nonselective beta-adrenergic blockade in coronary artery disease.

To examine the alterations in adaptive responses to training by nonselective beta-adrenergic blockade in patients with coronary artery disease (CAD), 26 patients were studied. Thirteen patients, aged 48 +/- 2 years (mean +/- standard error) were treated with beta-adrenergic blocking agents and another 13, aged 55 +/- 2 years, were control subjects. The 2 groups were similar in terms of initial maximal attainable O2 consumption (VO2max): 24 +/- 1 vs 25 +/- 2 ml/kg/min, patients and control subjects, respectively), and intensity (87 +/- 3.0 vs 88 +/- 2% of attainable VO2max), frequency (4 +/- 0.2 vs 4.0 +/- 0.3 days/week), and duration (12 months) of training. Maximal attainable VO2 increased to the same extent (36% vs 35%) in both groups. Heart rate (HR) at rest decreased to a similar extent in both groups (p less than 0.001). During submaximal exercise at the same exercise intensities, HR decreased in both groups, but to a larger extent in the control group than in the beta-blocker group after training. In the later, the reduced HR during submaximal exercise was solely due to training-induced bradycardia at rest. In contrast, the slower HR during submaximal exercise in control subjects after training was attributable to both bradycardia at rest and a smaller increase in HR during submaximal exercise. In both groups, the half-time of HR deceleration after cessation of exercise decreased (p less than 0.005) after training. However, the training-induced decrease in the half-time was significantly larger (p less than 0.025) in control subjects than in patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular sensitivity to epinephrine in the trained and untrained states.

Heart rate (HR), blood pressure (BP) and inotropic responses to acute exercise are partially mediated by sympathetic stimulation. Physical conditioning reduces exercise HR and improves maximal stroke volume and cardiac output. Uncertainty exists regarding the role of altered catecholamine sensitivity in producing these changes in man. In 6 highly trained men, noninvasive methods were used to serially assess the effect of cessation of training on the resting HR, BP and left ventricular contractile function in response to constant epinephrine infusion. Plasma epinephrine concentration during infusion did not vary with inactivity and was similar to that attained with strenuous exercise. Two subjects showed an increase in chronotropic sensitivity to epinephrine and 4 showed no consistent change. Despite a significant decline in exercise capacity and no apparent change in cardiac loading conditions, there was no persistent effect of inactivity on BP or left ventricular function as assessed by echocardiography and systolic time intervals. Therefore, an alteration in sensitivity to epinephrine is unlikely to account for the hemodynamic adaptations to endurance exercise training in healthy men.

Effect of exercise training on left ventricular performance in older women free of cardiopulmonary disease.

Endurance exercise training increases aerobic exercise capacity (maximal oxygen consumption rate [VO2max]) and attenuates the age-related decline in left ventricular (LV) function during exercise in older men. To determine whether similar adaptations occur in older women, 10 subjects (aged 63 +/- 4 years mean +/- SE) were studied before and after 9 to 12 months of endurance exercise training. They exercised 3.85 +/- 0.06 days/week at 81 +/- 0.3% of maximal heart rate. LV function at rest and during supine exercise was assessed by radionuclide ventriculography. VO2max was increased by 21% (from 1.40 +/- 0.1 to 1.7 +/- 0.1 liter/min; p < 0.001) in response to training. Maximal heart rate and systolic blood pressure during treadmill exercise were unchanged (161 +/- 5 beats/min before vs 164 +/- 3 beats/min after; p = NS, and 208 +/- 7 mm Hg before vs 214 +/- 8 mm Hg after; p = NS, respectively) after training. LV ejection fraction at rest (70.4 +/- 2% before vs 70 +/- 1% after) and during peak exercise (78.6 +/- 2% before vs 79.3 +/- 2% after) did not change in response to training. Furthermore, the increases in ejection fraction from rest to exercise were similar before and after training (change: 8.8 +/- 1 vs 9.1 +/- 1%). Stroke volume and cardiac output at peak exercise also did not change in response to training.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of adaptations to a 12-month exercise program and late outcome in patients with healed myocardial infarction and ejection fraction <45% and >50%.

To characterize the differences in adaptations to endurance exercise training and prognosis between patients with depressed and normal left ventricular (LV) function, 20 patients with coronary artery disease were studied and followed for 7 years. Patients with normal LV function had enhancement of LV systolic function, but the group with LV dysfunction did not exhibit cardiac adaptations and had more cardiac events than those with normal LV function.

Cardiac effects of prolonged and intense exercise training in patients with coronary artery disease.

The effects of intense and prolonged exercise training on the heart were studied with echocardiography in eight men with coronary artery disease with a mean age (+/- standard error of the mean) of 52 +/- 3 years. Training consisted of endurance exercise 3 times/week at 50 to 60 percent of the measured maximal oxygen uptake for 3 months followed by exercise 4 to 5 days/week at 70 to 80 percent of maximal oxygen uptake for 9 months. Maximal oxygen uptake capacity increased by 42 percent (26 +/- 1 versus 37 +/- 2 ml/kg per min; p less than 0.001). Heart rate at rest and submaximal heart rate and systolic blood pressure at a given work rate were significantly lower after training. Systolic blood pressure at the time of maximal exercise increased (145 +/- 9 before versus 166 +/- 8 mm Hg after training; probability [p] less than 0.01). Left ventricular end-diastolic diameter was increased after 12 months of training (from 47 +/- 1 to 51 +/- 1 mm; p less than 0.01). Left ventricular fractional shortening and mean velocity of circumferential shortening decreased progressively in response to graded isometric handgrip exercise before training but not after training. At comparable levels of blood pressure during static exercise, mean velocity of circumferential shortening was significantly higher after training (0.76 +/- 0.04 versus 0.98 +/- 0.07 diameter/sec, p less than 0.01). No improvement in echocardiographic or exercise variables was observed over a 12 month period in another group of five patients who did not exercise. Thus the data suggest that prolonged and vigorous exercise training in selected patients with coronary artery disease can elicit cardiac adaptations.

Effect of exercise training in 60- to 69-year-old persons with essential hypertension.

This study sought to determine whether 9 months of low- or moderate-intensity exercise training could decrease blood pressure (BP) in hypertensive men and women (mean age 64 +/- 3 years). Patients underwent weekly BP evaluations for 1 month to ensure that they had persistently elevated BP and then completed a maximal treadmill exercise test to exclude those with overt coronary artery disease. The low- and moderate-intensity groups trained at 53 and 73% of maximal oxygen consumption (VO2 max), respectively; however, total caloric expenditure per week was similar in both groups. VO2 max did not increase in the low-intensity group with training, but increased 28% in the moderate-intensity group. Diastolic BP decreased 11 to 12 mm Hg in both training groups. Systolic BP decreased 20 mm Hg in the low-intensity group with training, which was significantly greater than the change in the control and the moderate-intensity groups. Although systolic BP decreased 8 mm Hg in the moderate-intensity training group, this reduction was not significant. Training resulted in a somewhat lower cardiac output at rest in the low-intensity group, whereas total peripheral resistance decreased slightly in the moderate-intensity training group. Plasma and blood volumes, plasma renin levels and urinary sodium excretion did not change in either group with training. Both groups manifested lower plasma norepinephrine levels after training during standing rest, but not while supine. Thus, low-intensity training may lower BP as much or more than moderate-intensity training in older persons with essential hypertension, but the underlying mechanisms are unclear.

Left ventricular diastolic filling and its association with age.

Thirty normal subjects, aged 22 to 80 years, were studied by radionuclide ventriculography to determine the age dependence of cardiac ventricular diastolic function and to evaluate the association of other factors with ventricular diastolic performance. A strong negative correlation was found between peak diastolic filling rate and age (r = -0.82, p less than 0.0001). Partial correlation analysis was used to factor out the strong age dependence and yielded additional significant correlations of peak filling rate with heart rate (r = 0.48, p less than 0.01) and time to peak filling rate (r = -0.48, p less than 0.01). Time to peak filling rate is also correlated with heart rate but not definitely with age. Analysis by multiple linear regression yields an equation predicting peak filling rate from age and heart rate. Thus, the rate of rapid diastolic filling declines markedly with age in normal subjects. The association of peak filling rate with age and with other factors indicates the need for careful consideration of these factors in the interpretation of scintigraphic findings in patients with heart disease.

Effects of training on systolic time intervals at rest and during isometric exercise in men and women 61 to 64 years old.

To determine whether regular exercise improves left ventricular (LV) contractile function in persons 60 years and older, systolic time intervals (STIs) were measured in 10 healthy men and women (mean age 62 +/- 1 year [+/- standard deviation]) before and after 6 months of intense endurance training. STIs, systolic and diastolic blood pressure (BP) and heart rate (HR) were determined at rest and in response to isometric handgrip exercise. Systolic BP, diastolic BP and HR increased acutely from rest in response to handgrip (p less than 0.002). The indexes of total electromechanical systole and LV ejection time (ET) index increased (p less than 0.01), preejection period (PEP) index increased (p less than 0.05) or remained unchanged and PEP/LVET did not change from values at rest in response to handgrip. Training resulted in an 18% increase in maximal oxygen uptake (p less than 0.01). After training, systolic and diastolic BP were reduced at rest (p less than 0.002) and, along with HR, were lower in response to handgrip (p less than 0.002). However, training did not alter STIs at rest or during handgrip. These findings indicate that healthy persons in their 60s have a normal LV response to isometric exercise. Prolonged, intense endurance training does not alter LV contractile function at rest or in response to isometric exercise. However, training can significantly reduce BP at rest, and markedly lower the HR-systolic BP product attained during acute isometric stress, even in normotensive older subjects.

Effect of exercise training on the blood pressure and hemodynamic features of hypertensive adolescents.

Twenty-five adolescents (aged 16 +/- 1 years) whose blood pressure (BP) was persistently above the 95th percentile for their age and sex were studied before and after 6 +/- 1 months of exercise training and again 9 +/- 1 months after the cessation of training. Maximal oxygen consumption (VO2) increased significantly with training. There was no change in body weight or sum of skinfolds. Both systolic and diastolic BP decreased significantly with training; however, complete BP normalization was not achieved. When the subjects were retested 9 +/- 1 months after cessation of training, systolic BP and VO2 max had returned to pretraining levels; however, diastolic BP was still below pretraining levels in the subjects who had diastolic hypertension initially. Except in subjects who initially had an elevated cardiac output, no consistent hemodynamic changes were found with training or cessation of training to account for the reductions in BP. The subjects whose resting cardiac outputs were high initially had significantly lower cardiac outputs after training as a result of decreases in both heart rate and stroke volume; however, vascular resistance remained unchanged. Sedentary control subjects with similar BP had no significant change in any of the variables measured over a similar period. These data indicate that moderate endurance exercise training can lower BP in otherwise healthy hypertensive adolescents as an initial therapeutic intervention.

Left ventricular dysfunction after prolonged strenuous exercise in healthy subjects.

To determine whether depressed left ventricular (LV) contractile function can occur after prolonged and strenuous exercise, 12 healthy men, 26 +/- 1 years old (mean +/- standard error of the mean) were studied. The subjects exercised on a treadmill at 69 +/- 1% of maximal O2 uptake until exhaustion (170 +/- 10 minutes). Hemodynamic variables were measured before and 10 minutes after exhausting exercise. Baseline systolic blood pressure decreased from 124 +/- 2 to 113 +/- 3 mm Hg (p less than 0.001) after exhausting exercise. LV end-diastolic diameter, measured by echocardiography, decreased from 51 +/- 1.0 to 47 +/- 1.0 mm (p less than 0.005) but LV end-systolic diameter did not change (34 +/- 1.0 vs 34 +/- 1.0 mm). Both LV fractional shortening and the mean velocity of circumferential fiber shortening decreased (33 +/- 1 vs 28 +/- 1%; p less than 0.01 and 1.09 +/- 0.4 vs 0.97 +/- 0.05 circ/s; p less than 0.025) despite a lower end-systolic wall stress (sigma es = 88 +/- 4 vs 82 +/- 5, X 10(3) dynes/cm2; p less than 0.05) after prolonged exhausting exercise. A repeat bout of exercise of the same intensity but brief in duration (10 minutes) resulted in increases in LV fractional shortening (p less than 0.001) and mean velocity of circumferential fiber shortening (p less than 0.001), and a decrease in LV end-diastolic diameter (50 +/- 1.0 to 48 +/- 1.0 mm; p less than 0.05) at heart rates comparable to those attained after prolonged exhausting exercise. The results suggest that prolonged strenuous exercise may result in impaired LV function in healthy young subjects.

Elevated high-density lipoprotein cholesterol levels in older endurance athletes.

To ascertain whether older (masters) athletes exhibit a more favorable plasma lipoprotein/lipid profile than sedentary men of similar age, 14 endurance-trained masters athletes (mean age 60 +/- 2 years [+/- standard error of the mean]), 12 older, untrained-not lean men (mean age 62 +/- 1 years), 9 older untrained-lean men (mean age 61 +/- 2 years), 15 young endurance-trained athletes (mean age 26 +/- 1 years) and 15 young untrained men (mean age 28 +/- 1 years) were studied. The athletes had higher values for maximal oxygen uptake and lower levels of body fatness compared with the untrained men, regardless of age (p less than 0.05). High-density lipoprotein (HDL) cholesterol was markedly higher in the masters athletes than in the other groups (66 vs 42 to 55 mg/dl, p less than 0.05). The total cholesterol (TC) and low-density lipoprotein cholesterol concentrations of the masters athletes generally were higher than those of the younger groups, similar to those of the older lean men, and lower than those of the older-not lean men (p less than 0.05). The TC/HDL cholesterol ratios were similarly low (2.8 to 3.4) for the athletes and the young untrained men compared with the older untrained men (4.0 to 5.6) (p less than 0.05). Thus, some older endurance athletes exhibit markedly higher HDL cholesterol levels and lower TC/HDL cholesterol ratios compared with their sedentary peers. This favorable plasma lipoprotein profile may indicate a reduced risk of developing coronary artery disease for older men who exercise regularly.

Noninvasive assessment of changes in left ventricular function induced by graded isometric exercise in healthy subjects.

This study was designed to characterize the changes in left ventricular performance induced by graded isometric exercise. Fourteen healthy subjects (12 men and 2 women), aged 19 to 27, performed handgrip isometric exercise at 20, 40, and 60 percent of their maximal voluntary contraction (MVC) with three minutes of rest interval between each contraction. Left ventricular performance was assessed by M-mode echocardiography at rest and during each isometric contraction. Left ventricular end-diastolic and end-systolic dimensions did not change significantly. Heart rate and blood pressure increased significantly during each level of isometric contraction. Left ventricular posterior wall thickness fell from 8.6 +/- .4 (mean +/- SE) to 7.1 +/- .5 (P less than 0.01) and 6.5 +/- .4 mm (P less than 0.001) in response to 40 and 60 percent of MVC, respectively. Left ventricular wall thickness to radius ratio decreased progressively as systolic blood pressure increased which suggests increased wall tension. Fractional shortening remained unchanged during graded isometric exercise. However, mean velocity of circumferential fiber shortening (mVcf) increased from 1.08 +/- 0.4 to 1.24 +/- .05 circ/sec (P less than 0.005) in response to 60 percent of MVC. We conclude that the effect of isometric exercise on left ventricular performance depends, to some extent, on the relative strength of muscle contraction. In healthy subjects, isometric exercise of low intensity (less 40 percent of MVC) does not generally result in depression of left ventricular function. Higher levels of isometric exercise may modestly enhance left ventricular performance despite a sudden increase in blood pressure.

Prescribing exercise intensity for older women.

OBJECTIVE: For the purpose of prescribing exercise intensity, the American College of Sports Medicine (ACSM) provides guidelines for relating the perceived level of exertion and the heart rate (HR) response during exercise, expressed either as a percentage of maximal HR or of HR reserve, to a percentage of maximal aerobic power (VO2max). However, because maximal HR and VO2max decline with age, it is possible that these guidelines are not appropriate for an older population. The purpose of this study was to evaluate in 60- to 72-year-old women the relationships among the common methods of prescribing exercise intensity. DESIGN: Participants were 112 healthy but sedentary women, aged 66 +/- 4 years, who performed treadmill walking at four speeds. SETTING: Subjects were recruited from the community, and exercise tests were performed at a university laboratory facility. MEASUREMENTS: VO2max and maximal HR were determined during treadmill walking. The HR and VO2 responses to walking 6 minutes at each of four speeds ranging from 67 to 107 m/min, along with ratings of perceived exertion (RPE) and plasma lactate levels, were determined on a separate day. RESULTS: The exercise bouts required an average of 55 +/- 10%, 64 +/- 12%, 77 +/- 12%, and 91 +/- 9% of VO2max. Corresponding HR values were 64 +/- 8%, 70 +/- 9%, 81 +/- 10%, and 92 +/- 7% of maximal HR, and they were within the expected ranges based on ACSM guidelines. HR values as a percentage of HR reserve were much lower than expected based on the guidelines. RPE values were lower than expected at a given %VO2max, and plasma lactate levels were also relatively low, suggesting that older women are able to exercise at a higher percentage of VO2max than levels currently recommended. CONCLUSIONS: The results indicate that HR expressed as a percentage of maximal HR is an appropriate method of prescribing exercise intensity in healthy, sedentary 60- to 72-year-old women. The HR reserve method is not recommended in this population because it will likely result in the exercise being performed at a higher than expected percentage of VO2max.

Effect of endurance exercise training on left ventricular size and remodeling in older adults with hypertension.

BACKGROUND: It is not known whether exercise training can induce a reduction of blood pressure (BP) and a regression of left ventricular hypertrophy (LVH) in older hypertensive subjects. This study was designed to determine whether endurance exercise training, by lowering BP, can induce regression of LVH and left ventricular (LV) concentric remodeling in older hypertensive adults. METHODS: We studied 11 older adults with mild to moderate hypertension (BP 152.0 +/- 2.5/91.3 +/- 1.5 mm Hg, mean +/- SE), 65.5 +/- 1.2 years old, who exercised for 6.8 +/- 3.8 months. Seven sedentary hypertensive (BP 153 +/- 3/89 +/- 2 mm Hg) subjects, 68.5 +/- 1 years old, served as controls. LV size and geometry and function were assessed with the use of two-dimensional echocardiography. RESULTS: Exercise training increased aerobic power by 16% (p < .001), and it decreased systolic (p < .05) and diastolic (p < .05) BP, LV wall thickness (from 12.8 +/- 0.4 mm to 11.3 +/- 0.3 mm; p < .05), and the wall thickness-to-radius (h/r) ratio (from 0.48 +/- 0.02 to 0.41 +/- 0.01; p < .05). There were no significant changes in the controls. The changes in LV mass index (deltaLVMI) were different between the two groups. LV mass index decreased in the exercise group (deltaLVMI - 14.3 +/- 3.3 g) but not in the controls (deltaLVMI 1.4 +/- 4.1 g; p = .009). A multiple stepwise regression analysis showed that among clinical and physiological variables including changes in resting systolic BP, aerobic power, body mass index, and systolic BP during submaximal and maximal exercise, only the reduction in resting systolic BP correlated significantly with a regression of concentric remodeling (delta h/r ratio r = .80; p = .003). The other variables did not add to the ability of the model to predict changes in the h/r ratio. CONCLUSIONS: The data suggest that exercise training can reduce BP and induce partial regression of LVH and LV concentric remodeling in older adults with mild or moderate hypertension.