Ali A. Ehsani

Weight-Bearing Exercise Training and Lumbar Bone Mineral Content in Postmenopausal Women

STUDY OBJECTIVE To assess the effect of weight-bearing exercise training and subsequent detraining on lumbar bone mineral content in postmenopausal women. DESIGN Non-randomized, controlled, short-term (9 months) trial and long-term (22 months) exercise training and detraining (13 months). SETTING Section of applied physiology at a university school of medicine. PATIENTS Thirty-five healthy, sedentary postmenopausal women, 55 to 70 years old. All women completed the study. There was 90% compliance with exercise training. INTERVENTIONS All women were given calcium, 1500 mg daily. The exercise group did weight-bearing exercise (walking, jogging, stair climbing) at 70% to 90% of maximal oxygen uptake capacity for 50 to 60 min, 3 times weekly. MEASUREMENTS AND MAIN RESULTS Bone mineral content increased 5.2% (95% confidence interval [CI], 2.0% to 8.4%; P = 0.0037) above baseline after short-term training whereas there was no change (-1.4%) in the control group. After 22 months of exercise, bone mineral content was 6.1% (95% CI, 3.9% to 8.3% above baseline; P = 0.0001) in the long-term training group. After 13 months of decreased activity, bone mass was 1.1% above baseline in the detraining group. CONCLUSIONS Weight-bearing exercise led to significant increases above baseline in bone mineral content which were maintained with continued training in older, postmenopausal women. With reduced weight-bearing exercise, bone mass reverted to baseline levels. Further studies are needed to determine the threshold exercise prescription that will produce significant increases in bone mass.

Effects of aging, sex, and physical training on cardiovascular responses to exercise.

BackgroundThe relative contributions of decreases in maximal heart rate, stroke volume, and oxygen extraction and of changes in body weight and composition to the age-related decline in maximal oxygen uptake (V˙o2max) are unclear and may be influenced by sex and level of physical activity. Methods and ResultsTo investigate mechanisms by which aging, sex, and physical activity influence V˙o2max, we quantified V˙o2, cardiac output, and heart rate during submaximal and maximal treadmill exercise and assessed weight and fat-free mass in healthy younger and older sedentary and endurance exercise-trained men and women. For results expressed in milliliters per kilogram per minute, a three-to-four-decade greater age was associated with a 40–41% lower V˙o2max in sedentary subjects and a 25–32% lower V˙o2max in trained individuals (p < 0.001). A smaller stroke volume accounted for nearly 50%o of these age-related differences, and the remainder was explained by a lower maximal heart rate and reduced oxygen extraction (all p < 0.001). Age-related effects on maximal heart rate and oxygen extraction were attenuated in trained subjects (p < 0.05). After normalization ofV˙o2max and maximal cardiac output to fat-free mass, age- and training-related differences were reduced by 24–47% but remained significant (p < 0.05). For trained but not sedentary subjects, maximal cardiac output and stroke volume normalized to fat-free mass were greater in men than in women (p < 0.05). ConclusionsA lower stroke volume, heart rate, and arteriovenous oxygen difference at maximal exercise all contribute to the age-related decline in V˙o2max. Effects of age and training on V˙o2max, maximal cardiac output, and stroke volume cannot be fully explained by differences in body composition. In sedentary subjects, however, the sex difference in maximal cardiac output and stroke volume can be accounted for by the greater percentage of body fat in women than in men.

Effects of Exercise Training on Frailty in Community‐Dwelling Older Adults: Results of a Randomized, Controlled Trial

OBJECTIVES: Although deficits in skeletal muscle strength, gait, balance, and oxygen uptake are potentially reversible causes of frailty, the efficacy of exercise in reversing frailty in community‐dwelling older adults has not been proven. The aim of this study was to determine the effects of intensive exercise training (ET) on measures of physical frailty in older community‐dwelling men and women.

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.

The influence of location and extent of myocardial infarction on long-term ventricular dysrhythmia and mortality.

Although the extent of enzymatically estimated infarct size appears to be an important determinant of morbidity and mortality early after infarction, its influences on long-term survival and late ventricular dysrhythmia have not yet been characterized. Accordingly, we prospectively studied 173 patients younger than 66 years of age without evidence of prior myocardial infarction, who survived acute myocardial infarction for at least 24 hours. Infarct size was estimated enzymatically and dysrhythmia quantified by computer from two-channel, 24-hour ambulatory ECGs. The mean infarct size index (ISI) of those who died was significantly larger than that of survivors (46.5 ± 5.8 (SEM) vs 21.1 i 1.4 CK-g-Eq/m2, p < 0.001). Overall survival was significantly better after small (ISI < 15 CK-g-Eq/m2) or modest infarcts (15 < ISI < 30) than after large infarcts (ISI 30) (p < 0.01, p < 0.05, respectively). Regardless of the locus of the infarction, patients with small infarcts had a better prognosis than those with larger infarcts. Late mortality was comparable after transmural and subendocardial infarction, but higher after anterior than after inferior infarction (15% vs 6%; p < 0.05). Among the 10 clinical and hemodynamic variables evaluated with multivariate analysis, ISI (but not infarct locus), peak plasma creatine kinase, congestive failure at the time of admission, age and gender were significantly related to mortality. Premature ventricular complexes were more frequent among patients with modest or large infarcts (ISI 15) throughout the follow-up (p < 0.05), regardless of infarct locus. Thus, the extent of infarction is a strong determinant of both ventricular dysrhythmia and mortality, late as well as early after acute myocardial infarction.

Rapid Changes in Left Ventricular Dimensions and Mass in Response to Physical Conditioning and Deconditioning

Abstract To determine the influence of training and detraining on left ventricular dimensions, echocardiographic estimates of left ventricular indexes were undertaken in two groups of young healthy subjects. The training group consisted of eight competitive swimmers who were studied serially for 9 weeks. Left ventricular end-diastolic dimension in this group increased from the pretraining value of 48.7 ± 1.7 (mean ± standard error) to 53 ± 0.2 mm by the 1st week and to 52 ± 1.7 mm by the 9th week of training (P The results indicate that (1) exercise training-induced adaptive changes in left ventricular dimensions occur rapidly and mimic the pattern of chronic volume overload; and (2) modest degrees of exercise-induced left ventricular enlargement are reversible after cessation of training.

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 ∼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 Wards triangle region of the proximal femur (6.1 ± 1.5% and 5.1 ± 2.1%, respectively). There was a significant increase 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.

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 electrical countershock on serum creatine phosphokinase (CPK) isoenzyme activity

Total and MB serum creatine phosphokinase (CPK) activity levels were measured serially in 30 patients treated with direct current electrical countershock, 17 patients with acute myocardial infarction and 25 normal subjects. In addition, serial determinations of total and MB CPK in serum were performed in 11 closed chest anesthetized dogs subjected to 10 repetitive countershocks at 15 second intervals with a delivered energy of 240 joules per countershock. Less than 4 milli-international units (mlU)/ml of MB CPK was found in the serum of normal subjects. Patients with myocardial infarction whose elevated total CPK levels were comparable with those of patients treated with cardioversion had a usbstantial rise in MB CPK activity, with peak values averaging 39 +/- 6 mlU/ml (mean +/- standard error). Fifteen of the 30 patients treated with countershock had elevated total CPK activity that peaked within 4 hours. In this group, MM CPK elevations accounted for the overall rise in CPK activity. In two patients, modest elevations of MB CPK (11 and 13 mlU/ml, respectively) were observed after cardioversion. In all 11 dogs total CPK increased after countershock, peaking to 1,888 +/- 410 MLU/ml within 6 hours. Six dogs had increased MB CPK activity (52+/- 6 mlU/ml) and myocardial necrosis demonstrable histologically 4 days later. The results indicate that (1) myocardial damage in dogs produced by intense, repetitive countershock is associated with increased serum MB CPK; and (2) countershock as conventionally used in patients does not generally produce myocardial damage and serum MB CPK elevation. Although release of MB CPK into serum occasionally occurs after countershock, perhaps reflecting myocardial damage, the elevations appear to be modest. Thus, electrical countershock does not obscure the diagnosis of myocardial infarction or impair quantitative assessment of the extent of myocardial damage based on analysis of serum MB CPK activity.

Resistive training can reduce coronary risk factors without altering VO2max or percent body fat.

Eleven healthy, untrained males (age = 44 +/- 1 yr; range = 40 to 55 yr) were studied to determine the effects of 16 wk of high-intensity resistive training on risk factors for coronary artery disease. Lipoprotein-lipid profiles, plasma glucose and insulin responses during an oral glucose tolerance test, and blood pressure at rest were determined before and after training. The training program resulted in a 13% increase in high-density lipoprotein-cholesterol (39 +/- 2 vs 44 +/- 3 mg.dl-1, P less than 0.05), a 43% increase in high-density lipoprotein-cholesterol (7 +/- 2 vs 10 +/- 2 mg.dl-1, P less than 0.05), a 5% reduction in low-density lipoprotein cholesterol (129 +/- 5 vs 122 +/- 5 mg.dl-1, P less than 0.05), and an 8% decrease in the total cholesterol/high-density lipoprotein-cholesterol ratio (5.1 +/- 0.3 vs 4.7 +/- 0.3, P less than 0.01), despite no changes in VO2max, body weight, or percent body fat. Glucose-stimulated plasma insulin concentrations during oral glucose tolerance testing were significantly lower, and supine diastolic blood pressure was reduced (P less than 0.05) as a result of the training program. No changes in any of these variables occurred in a sedentary control group. These findings indicate that resistive training can lower risk factors for coronary artery disease independent of changes in VO2max, body weight, or body composition.