Concentric and eccentric isokinetic resistance training similarly increases muscular strength, fat-free soft tissue mass, and specific bone mineral measurements in young women.

UNLABELLED: Women participated in 5 months of unilateral concentric (n = 37) or eccentric (n = 33) isokinetic resistance training of the legs and arms. Limb muscular strength increased as did total body, leg, and arm fat-free soft tissue mass, total body BMC, hip BMD, and forearm BMC and BMD. Isokinetic training benefits bone mineral acquisition. INTRODUCTION AND HYPOTHESIS: Isokinetic resistance training (IRT) is osteogenic; however, it is not known if concentric or eccentric modalities of IRT produce differential effects on bone. We tested our hypothesis that high-load eccentric versus concentric mode of IRT would produce greater increases in muscular strength, fat-free soft tissue mass (FFSTM), bone mineral density (BMD) and content (BMC) in trained legs and arms. METHODS: Participants were randomized to 5 months of concentric (n = 37) or eccentric (n = 33) training. The non-dominant leg and arm were used during training; dominant limbs served as controls. Muscular strength was measured with an isokinetic dynamometer; body composition was measured by dual-energy X-ray absorptiometry. RESULTS: Muscular strength of the concentrically and eccentrically trained leg (18.6%; 28.9%) and arm (12.5%; 24.6%) significantly increased with training. Gains in total body (TB) BMC (p < 0.05) and, in the trained limbs, total proximal femur BMD (p < 0.05) and total forearm BMD (p < 0.05) and BMC (p < 0.05) occurred in both groups. FFSTM increased for the TB and trained leg and arm (all p < 0.001) in both modes. CONCLUSION: Regardless of the mode, high-intensity, slow-velocity IRT increases muscular strength and FFSTM of trained limbs and imparts benefits to TB BMC and site-specific BMD and BMC in young women.

Relationships among bone mineral density, body composition, and isokinetic strength in young women.

The purpose of this study was to examine the relationships among bone mineral density (BMD), body composition, and isokinetic strength in young women. Subjects were 76 women (age: 20 +/- 2 yr, height: 164 +/- 6 cm, weight: 57 +/- 6 kg, body fat: 27 +/- 4%) with a normal body mass index (18-25 kg/m(2)). Total body, nondominant proximal femur, and nondominant distal forearm BMD were measured with dual-energy x-ray absorptiometry. Isokinetic concentric (CON) and eccentric (ECC) strength of the nondominant thigh and upper arm were measured at 60 deg/sec. Fat-free mass (FFM) correlated (P < 0.001) with BMD of the total body (r = 0.56) and femoral neck (r = 0.52), whereas fat mass (FM) did not relate to BMD at any site. Leg FFM, but not FM, correlated with BMD in all regions of interest at the proximal femur. Weak associations were observed between arm FFM and forearm BMD. Isokinetic strength did not relate to BMD at any site after correcting for regional FFM. In conclusion, strong, independent associations exist between BMD and FFM, but not FM or isokinetic strength, in young women.

The influence of patient strength, aerobic capacity and body composition upon outcomes after coronary artery bypass grafting.

BACKGROUND: Physical activity, physical fitness and body habitus of patients may be important predictors of outcomes after cardiac surgery. This study sought to quantify physical fitness and determine whether components of fitness enhance the prediction of outcomes in a group of patients undergoing coronary artery bypass grafting. METHODS: A group of 200 patients were evaluated prior to coronary artery bypass surgery. A Veterans Specific Activity Questionnaire (VSAQ) measured aerobic capacity. A grip dynamometer assessed strength. Skin-fold thickness was used to calculate percent body fat and lean body mass index. Patients were divided into low risk (0-2.5%) and high risk (>2.5%) groups based on the STS National Cardiac Surgery Database prediction of operative mortality. RESULTS: Patients with both a high percent body fat and a low VSAQ were at higher risk for at least one serious complication (p<0.05) and a longer postoperative length of stay (p<0.05). CONCLUSION: This study suggests: 1) An index of physical fitness can be obtained preoperatively in cardiac surgical patients; 2) This information aids in the prediction of operative risk.

Effects of combined aerobic and resistance training versus aerobic training alone in cardiac rehabilitation.

PURPOSE: This study examined the effects of performing combined resistance and aerobic training, versus aerobic training alone, in patients with coronary artery disease. METHODS: Thirty-six patients with coronary artery disease were randomized to either an aerobic-only training group (AE) or a combined aerobic and resistance training group (AE + R). Both groups performed 30 minutes of aerobic exercise 3 days/week for 6 months. In addition, AE + R group performed two sets of resistance exercise on seven different Nautilus machines after completion of aerobic training each day. Twenty patients (AE: n = 10; AE + R: n = 10) completed the training protocol with > 70% attendance. RESULTS: Strength gains for AE + R group were greater than for AE group on six of seven resistance machines (P < 0.05). VO2peak increased after training for both AE and AE + R (P < 0.01) with no difference in improvement between the groups. Resting and submaximal exercise heart rates and rate-pressure product were lower after training in the AE + R group (P < 0.01), but not in the AE group. AE + R increased lean mass in arm, trunk, and total body regions (P < 0.01), while AE increased lean mass in trunk region only (P < 0.01). Percent body fat was reduced for AE + R after training (P < 0.05) with a between group trend toward reduced body fat (P = 0.09). Lean mass gain significantly correlated with strength increase in five of seven resistance exercises for AE + R. CONCLUSIONS: Resistance training adds to the effects of aerobic training in cardiac rehabilitation patients by improving muscular strength, increasing lean body mass, and reducing body fat.

Effects of short-term PAP treatment on endurance exercise performance in obstructive sleep apnea patients.

Objective: To measure the effects of 4 weeks of nasal positive airway pressure therapy (PAP) on exercise performance in obstructive sleep apnea patients (OSA).Background: Little published research is available which describes the effects of OSA on exercise tolerance or upon the potential of exercise testing to evaluate the outcomes of PAP therapy.Methods: Exercise testing was performed on an electronic cycle ergometer with continuous ramping to allow collection of numerous data points for each subject, up to a vigorous terminal intensity. Linear regression established each subject's pre-treatment scores for the dependent variables at 60% of estimated peak power (W(60%)). Responses at the pre-treatment W(60%) test were used to quantify and compare to responses at the same power output after treatment.Results: OSA by nocturnal polysomnography was moderately severe in this group; the respiratory distress index was 48+/-22 (mean+/-SD; n=9). Exercise heart rates after PAP therapy averaged 10.2 bt/min less at W(60%) (P<0.05). Other variables were lower but non-significantly so, further suggesting a lower cardiorespiratory exercise demand after treatment, i.e. oxygen consumption ( downward arrow7.6%), and Rating of Perceived Exertion ( downward arrow8.8%).Conclusion: Brief treatment with PAP therapy improves objective markers of aerobic exercise performance.

The effect of indomethacin on the circulatory and plasma noradrenaline responses to cold pressor testing in normal subjects.

Prostaglandins may alter neuronal noradrenaline release or vascular responsiveness to sympathoexcitation. The purpose of this study was to determine if indomethacin, a prostaglandin synthesis inhibitor, influences the sympathetic and circulatory adjustments to a commonly utilized laboratory stressor in the clinical assessment of autonomic function, the cold pressor test. Venous plasma noradrenaline levels (n = 8), mean arterial pressure and heart rate (n = 10) were measured in healthy male subjects during immersion of the non-dominant hand in cold water (1 degree C) for 90 s. The subjects were given either placebo or indomethacin (100 mg) in a double-blind manner. The order of administration was counterbalanced and a 1 week period was given for systemic clearance of the drug. The absolute level of mean arterial pressure was elevated during the resting control period after indomethacin treatment (88 in placebo vs. 92 mmHg in indomethacin). Both heart rate and venous plasma noradrenaline levels were similar between trials during the resting control period. Mean arterial pressure and heart rate increased similarly during cold pressor testing in both indomethacin and placebo. Venous plasma noradrenaline levels increased during cold pressor testing 162 +/- 39 vs. 200 +/- 69 pg/ml in indomethacin vs. placebo (p > 0.05), respectively. In addition, perceived pain (peak level = 7 +/- 1 vs. 6 +/- 1 units; indomethacin vs. placebo, respectively) was not different between the trials. These results suggest that administration of indomethacin in a maximal single therapeutic dose, does not affect the sympathetic nervous system or circulatory responsiveness to cold pressor testing. It may not be necessary to discontinue indomethacin prior to autonomic function testing.

Effect of indomethacin on the pressor responses to sustained isometric contraction in humans.

The purpose of this study was to test the hypothesis that prostaglandins participate in metaboreceptor stimulation of the pressor response to sustained isometric handgrip contraction in humans. To accomplish this, mean arterial pressure, heart rate (n = 10), and plasma norepinephrine levels (n = 8) were measured in healthy male subjects during sustained isometric handgrip at 40% of maximal voluntary contraction force to exhaustion and during a period of postcontraction muscle ischemia. The subjects were given a double-blind and counterbalanced administration of placebo or a single 100-mg dose of indomethacin. A period of 1 wk was allowed for systemic clearance of the drug. Mean arterial pressure increased 25 +/- 5 vs. 22 +/- 4 mmHg during the final minute of isometric handgrip contraction and 26 +/- 2 vs. 21 +/- 5 during the last minute of postcontraction muscle ischemia in the placebo vs. the indomethacin trial (P > 0.05), respectively. Heart rate was increased 21 +/- 4 vs. 17 +/- 3 beats/min during the final minute of isometric handgrip contraction in the placebo vs. the indomethacin trial (P > 0.05), respectively, and returned to control values during postcontraction muscle ischemia. Plasma norepinephrine levels increased 343 +/- 89 vs. 289 +/- 89 pg/ml after isometric handgrip contraction and 675 +/- 132 vs. 632 +/- 132 pg/ml after postcontraction muscle ischemia (P > 0.05) in the placebo vs. the indomethacin trial, respectively. These results suggest that prostaglandin inhibition does not significantly modulate muscle contraction-induced stimulation of mean arterial pressure, heart rate, or plasma norepinephrine levels.

Comparison of computer ST criteria for diagnosis of severe coronary artery disease.

To determine which computer ST criteria are superior for predicting patterns and severity of coronary artery disease during exercise testing, 230 male veterans were studied who had both coronary angiography and a treadmill exercise test. Significant (p < or = 0.05) differences in computer-scored ST criteria were observed among patients with progressively increasing disease severity. Three-vessel/left main disease produced responses significantly different from 1- and 2-vessel disease or those with < 70% occlusion. Discriminant function analysis revealed that horizontal or downsloping ST depression measured at the J junction during exercise or recovery, or both, was the most powerful predictor of severe disease. With use of a cut point of 0.075 mV ST depression, horizontal or downsloping ST depression alone yielded a sensitivity of 50% (95% confidence interval = 35 to 65%) and specificity of 71% for prediction of severe disease; the only additional variable that added significantly to the prediction was exercise capacity, which improved sensitivity to 57% (95% confidence interval = 41 to 72%) with no change in specificity. Measurements of ST amplitude at the J junction and at 60 ms after the J point without slope considered and other scores, including the Treadmill Exercise Score, ST Integral, and ST/heart rate index, had a lower but comparable predictive accuracy when compared with horizontal or downsloping ST depression. Prediction of coronary artery disease severity can be achieved using computerized electrocardiographic measurements obtained during exercise testing. The most powerful marker for severe coronary artery disease is the amount of horizontal or downsloping ST-segment depression during exercise or recovery, or both, a measurement that stimulates the traditional visual approach.

Opioid antagonism, perceived exertion and tolerance to exercise-thermal stress.

In an attempt to investigate the physiological responses to opioid receptor blockade during exercise in the heat, five male volunteers completed two bouts of stationary cycling at 70% VO2max in a hot (33 degrees C765% RH) environment. Exercise was conducted following the administration of either naloxone or saline (4 mg i.v.) five minutes prior to exercise. A second 4 mg dose was administered at 25 minutes of exercise. Performance time was 11% shorter (p = 0.06), and RPE response was significantly higher at test termination on naloxone. No drug effect was observed on rectal or mean skin temperature during exercise. Forearm blood flow (FBF) was higher on naloxone, while exercise heart rates were lower on the drug versus saline. No significant changes were observed in estimated mean arterial pressure or gross sweat responses to exercise. Plasma immunoreactive beta-endorphin was significantly elevated in the naloxone trial only. Thus, while opioids may play some hemodynamic role during exercise in the heat, it appears that opioid mediation of the perceived stress of exercise contributes more to an individual's thermal tolerance. Additionally, the results suggest that perceptual and hemodynamic/cardiovascular responses that may be mediated by these peptides are dissociable phenomena.

Effects of alpha 1-receptor blockade on the hemodynamic responses to exercise in young hypertensives.

The purpose of this study was to determine if alpha 1-adrenergic receptor blockade alters the hemodynamic response to exercise in young (less than 25 yr) male borderline hypertensives differently than in young normotensives. Five hypertensive (HTN, MAP greater than 105 mmHg) and 7 normotensive (NTN, MAP less than 95 mmHg) college-age males underwent two 30 min bouts of cycle ergometry exercise at 50% VO2pk in a warm (25 degrees C, 50% rh) environment; one following alpha 1-receptor blockade with prazosin (PRAZ) and the other following placebo administration (PLAC). During resting PLAC and compared to NTN, HTN exhibited an elevated cardiac index (CI, p = .002), similar HR and elevated total peripheral resistance index (TPRI, p = .015). During resting PRAZ, CI and TPRI were similar but HR was higher (p = .013) in HTN than NTN. While reduced during PRAZ, resting MAP was higher in HTN than NTN (p = .007) for both trials. With exercise and PLAC, CI was higher (p = .029) while HR and TPRI were similar for HTN compared to NTN. With PRAZ, the exercise CI, TPRI and HR responses were similar for both groups. Exercise MAP was blunted in both groups with PRAZ. While not differing significantly between groups for each treatment, MAP was stable for NTN while it declined after 10 min of exercise in HTN. The elevated CI seen in exercising HTN with PLAC was removed with PRAZ; the exercise response was otherwise unaltered by alpha 1-blockade. Consequently, these data suggest that young male hypertensives have an elevated blood pressure due to an elevated CI incompletely offset by a reduced TPRI. While alpha 1-blockade lowers MAP by lowering CI, the MAP response to exercise remains unaltered.

Post-myocardial infarction exercise testing. Non-Q wave versus Q wave correlation with coronary angiography and long-term prognosis.

BACKGROUND: The presence or absence of baseline diagnostic Q waves has been believed to compromise the accuracy of standard exercise electrocardiography in identifying severe coronary artery disease (three-vessel and/or left main disease); therefore, a retrospective analysis was performed using a personal computer data base of exercise test responses and cardiac catheterization results to evaluate this premise, and follow-up was performed to observe how Q waves and/or severe coronary disease impacted on survival. METHODS AND RESULTS: Two hundred fifty-three male patients who had survived a myocardial infarction were studied. Patients on digitalis, those with left bundle branch block or left ventricular hypertrophy on their baseline electrocardiogram, those with previous revascularization procedures, and those with significant valvular or congenital heart disease were excluded. All patients performed either a low-level predischarge or a sign/symptom limited exercise test and underwent diagnostic coronary angiography within 32 days of each test (range, 0-90 days). Long-term follow-up on patients was performed for an average of 45 months (+/- 17 months). Group NQMI comprised 103 post-myocardial infarction patients lacking Q waves at the time of exercise testing and group QMI comprised 150 patients who developed Q waves with their myocardial infarction. The cut points of greater than or equal to 1 mm (chi 2 = 14.39, p less than 0.001) and greater than or equal to 2 mm (chi 2 = 26.11, p less than 0.001) of exercise-induced ST segment depression were reliable markers of severe coronary disease in Q wave infarct survivors. This was also true for non-Q wave infarct survivors as greater than or equal to 1 mm (chi 2 = 6.02, p = 0.01) and greater than or equal to 2 mm (chi 2 = 4.37, p = 0.04) of ST segment depression were reliable markers of severe coronary disease. Receiver operating characteristic curve analysis revealed that exercise-induced ST segment depression had discriminating power for the identification of severe coronary artery disease in both the Q wave myocardial infarction patients (area = 0.735, z = 4.47, p less than 0.001) and the non-Q wave infarct patients (area = 0.700, z = 3.20, p less than 0.001). After 4.4 years of cumulative follow-up, patients with severe coronary disease had an infarct-free survival rate of 72% (95%, CI, 50.0-86.0%), whereas those without severe disease had an 86% (95% CI, 76.5-91.5%) infarct-free survival rate (Cox chi 2 = 4.00, p = 0.045). Non-Q wave patients had an infarct-free survival rate of 81% (95% CI, 66.0-89.5%), whereas those with Q waves had an infarct-free survival rate of 85% (95% CI, 73.9-91.3%) (Cox chi 2 = 0.0005, p = NS). CONCLUSIONS: The presence or absence of diagnostic Q waves has no significant effect on the ability of the exercise electrocardiogram to identify severe coronary artery disease in survivors of myocardial infarction. Long-term infarct-free survival of patients with myocardial infarction is more related to the presence of severe coronary disease rather than if they suffered a non-Q wave or Q wave infarction.

Effect of beta-blockade on the interpretation of the exercise ECG: ST level versus delta ST/HR index.

The diagnostic value of exercise-induced ST segment depression is considered to be decreased in patients receiving beta-blockers. One approach to improving predictive accuracy has been to use the ratio of maximal change in exercise-induced ST segment depression to the corresponding maximal change in heart rate (delta ST/HR index). The present study compared these two ECG methods. The records of exercise tests performed on 3047 male veterans were screened to exclude patients with prior revascularization procedures or myocardial infarction, those receiving digoxin, and those with certain resting ECG abnormalities; the use of beta-blocker drugs at the time of testing was also noted. All exercise tests were sign/symptom limited. Significant angiographic coronary disease was defined as greater than or equal to 75% reduction in luminal diameter of at least one coronary artery. Disease severity was evaluated in an expanded study group that included patients with prior myocardial infarction. Mean maximal heart rate was 21 beats.min-1 lower for those receiving beta-blockers (p less than 0.05), but there was no difference in mean metabolic equivalent (MET) level achieved. The diagnostic accuracy of an abnormal test result for determination of the presence or absence of coronary artery disease was not significantly different in the subgroup taking beta-blockers versus the subgroup not taking beta-blockers (N = 200), and use of the delta ST/HR index did not improve test performance. For discrimination of severe disease, test accuracy was also unaffected by beta-blockers and was not improved by the delta ST/HR index (N = 454).(ABSTRACT TRUNCATED AT 250 WORDS)

Legal issues in the delivery of worksite health promotion.

Employee health promotion programs typically involve one or more of the following: (1) education programs, (2) cholesterol, blood pressure, diabetes, or other similar screening programs, (3) smoking cessation programs, (4) drug/alcohol testing and counseling programs, (5) exercise facility or activity programs, and (6) recreational activity programs. The authors examine potential legal implications of these activities. This chapter is intended for those attempting to define and establish these programs or to focus and operate them without undue conflict or legal system involvement.

Legal Aspects of Cardiac Rehabilitation Exercise Programs.

In brief: Cardiac rehabilitation as a distinct c health care service is of fairly recent origin, and existing programs are rather broad and nonstandardized. Consequently, the malpractice crisis that has engulfed the medical profession may well affect professionals who practice cardiac rehabilitation. Various legal issues and concerns face cardiac rehabilitation programs, as they do any other health care provider group. The adoption of written program policies and procedures, set in accordance with national standards of practice, can address the legal and practical problems. Obtaining effective informed consent from patients and using various risk management techniques can also assist in the operation of safe and legally defensible cardiac rehabilitation programs.

Exercise-thermoregulatory stress and increased plasma beta-endorphin/beta-lipotropin in humans.

Six adult male volunteers of similar body composition and physical fitness were tested to determine plasma immunoreactive beta-endorphin/beta-lipotropin (beta-EN/beta-LPH) response under three exercise-thermoregulatory stress conditions. The experimental protocol consisted of 120 min of stationary upright cycling at 50% VO2max under neutral (24 degrees C, 50% rh)-euhydration (NE), hot (35 degrees C, 50% RH)-euhydration (HE), and hot-dehydration (HD) environmental conditions. beta-EN/beta-LPH was calculated by radioimmunoassay at -30-min, 0-min, and 15-min intervals thereafter. Change in plasma volume (delta PV) was measured to determine its effect on beta-EN/beta-LPH concentration. Preexercise beta-EN/beta-LPH levels averaged 23.7 +/- 2.6 pg X ml-1 in all conditions. The greatest beta-EN/beta-LPH response occurred at 105 min in HD conditions when levels rose to 43.2 +/- 6.9 pg X ml-1. Exercise in HD and HE conditions resulted in significantly (P less than 0.05) elevated beta-EN/beta-LPH above levels observed in NE. delta PV did not account for more than 10% of beta-EN/beta-LPH changes at any time interval. The beta-EN/beta-LPH response pattern closely paralleled rectal temperature changes in all conditions. These data suggest that conditions of increasing exercise thermoregulatory stress are associated with increasing peripheral beta-endorphin concentration.

Effects of short-term aerobic conditioning and high cholesterol feeding on plasma total and lipoprotein cholesterol levels in sedentary young men.

The plasma total cholesterol (TC) and lipoprotein cholesterol concentrations of sedentary young men (n = 23) were determined during 4 wk of controlled feeding and 6 wk of supervised aerobic conditioning. Subjects were assigned to dietary treatments of 400 mg cholesterol per day (M) or 1400 mg cholesterol per day (H); both diets had a P/S ratio of about 0.6. Dietary groups M and H were subdivided into exercise (MX and HX) and sedentary (MS and HS) groups. Compared to the sedentary groups, MX and HX exhibited significant (p less than 0.01) improvements in cardiorespiratory fitness. After 2 and 4 wk of high cholesterol feeding, group HS exhibited significant (p less than 0.05) elevations in TC (+30 +/- 7 and +32 +/- 9 mg/dl) with nonsignificant increases in very low-density lipoprotein cholesterol and low-density lipoprotein cholesterol. Group HX exhibited consistent weekly increases in high-density lipoprotein cholesterol (HDL-C) (from 46 +/- 3 mg/dl, the base level, to 53 +/- 4 mg/dl at wk 4) with aerobic conditioning. By combining exercise and sedentary group data at each level of dietary cholesterol it was shown that TC and HDL-C levels significantly (p less than 0.05) increased by the 4th wk of high cholesterol feeding. The TC/HDL-C ratio significantly (p less than 0.05) increased for the sedentary subjects as compared to all the exercising subjects by wk 4 of controlled feeding.

Effect of coarse wheat bran fiber and exercise on plasma lipids and lipoproteins in moderately overweight men.

The effects of the American Association of Cereal Chemists coarse wheat bran fiber and exercise were evaluated in 20 males, aged 24 to 35 yr, and at least 10% above ideal weight. Thirteen of the subjects participated in a 4 mile walk-jog run program 3 times weekly. In a cross-over design with diets switched midway through the experiment, both the exercising and sedentary groups consumed isocaloric amounts of either white bread or white bread containing wheat bran (0.5 g/kg body weight). Plasma total and lipoprotein cholesterol and triglycerides, body weights, and percentage body fats were determined at 0, 6, and 12 wk. No consistent effects were observed as a result of the wheat bran feeding on any of the parameters measured. Exercise training tended to decrease body weights and percentage body fats, and was associated with significantly increased (p less than 0.05) plasma high-density lipoprotein cholesterol levels and high-density lipoprotein cholesterol to low-density lipoprotein cholesterol ratios. After a rise in triglycerides at wk 6, a significant decline (p less than 0.05) back to base-line values was observed at wk 12 for the exercised subjects.

The effects of fatigue on the control of a coincident timing response.

The present study investigated the extent to which fatigue influenced the usage of feedback by Ss to make corrections during coincident timing responses. Sixteen college males watched a .01-sec timer and attempted to knock over a barrier at the moment that the sweep hand reached 500 msec. All Ss were given 50 trials of practice on each of four consecutive days. The fatigue group's performance was immediately preceded by a response-specific local fatigue (dynamic exercise). To insure the maintenance of a high level of fatigue throughout practice, the fatiguing exercise was interspersed with the coincident timing task. The control group performed the same exercise as the fatigue group but without any resistance. Schmidt's (1972) index of preprogramming (IP) was calculated for each day in order to determine the level of feedback involvement in controlling the movement. Fatigue did not influence the accuracy with which Ss responded or the rate that they learned. However, the results indicated a relatively high and stable IP throughout all trials with the IP for the fatigue group higher than that of the control, suggesting a preference by these Ss for a programming mode of control.