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At least 127 records · Page 7Linked to original sources

PubMed2000

Effects of prior exercise on eccentric exercise-induced neutrophilia and enzyme release.

PURPOSE: The purpose of this study was to determine the effects of prior exercise on changes in circulating neutrophils, neutrophil activation, and myocellular enzymes following a standardized bout of eccentric exercise. METHODS: Twenty-four male volunteers were randomized into three groups (N = 8). Group C performed 10 sets of 10 eccentric contractions of the quadriceps muscles with both legs (100% of the concentric IRM). Group D and Group F exercised for 2 h at 56%VO2max on a cycle ergometer followed by a similar bout of eccentric contractions. Group F also received 7.5 mL x kg(-1) of a carbohydrate-electrolyte beverage every 30 min during the submaximal exercise, whereas group D received no fluid. RESULTS: Body weight remained unchanged in groups C and F and decreased in group D by 1.56 +/- 0.34 kg. Ultrastructural Z-Band damage increased three-fold following exercise and remained elevated 3 d after exercise but was not different among groups. Circulating neutrophils were elevated more in group D compared with those in group C immediately after the exercise or rest period, and this difference persisted 3 h after the eccentric exercise. Serum lactoferrin concentrations increased 3.3-fold after exercise in all groups (P < 0.01). Creatine kinase levels (CK) rose in all subjects, with subjects in Group F and D having a significantly greater rise in CK after exercise compared with those in group C. CONCLUSIONS: These data indicate that submaximal exercise followed by a bout of eccentric exercise results in similar amounts of myofibrillar injury with a larger neutrophil response and CK release.

Adult↗

PubMed1999

Norepinephrine response to exercise at the same relative intensity before and after endurance exercise training.

It is well documented that endurance exercise training results in a blunted norepinephrine (NE) response to exercise of a given absolute exercise intensity. However, it is not clear what effect training has on the catecholamine response to exercise of the same relative intensity because previous studies have provided conflicting results. The purpose of the present study was, therefore, to determine the catecholamine response to exercise of the same relative exercise intensity before and after endurance exercise training. Six women and three men [age 28 +/- 8 (SD) yr] performed 10 wk of training. Maximal O2 uptake (VO2 max) was determined during treadmill exercise. Fifteen-minute treadmill exercise bouts were performed at 60, 65, 70, 75, 80, and 85% of VO2 max before and after training. VO2 max was increased by 20% (from 39.2 +/- 7.7 to 46.9 +/- 8.1 ml. kg-1. min-1; P < 0.05) in response to training. Plasma NE concentrations were higher (P < 0.05) during exercise at the same relative intensity after, compared with before, training at 65-85% of VO2 max. Differences between heart rates and plasma epinephrine concentrations after, compared with before, training were not statistically significant. These results provide evidence that the NE response to exercise is dependent on the absolute as well as the relative intensity of the exercise.

Adult↗

PubMed2000

Effects of exercise intensity on the sweating response to a sustained static exercise.

To investigate how the sweating response to a sustained handgrip exercise depends on changes in the exercise intensity, the sweating response to exercise was measured in eight healthy male subjects. Each subject lay in the supine position in a climatic chamber (35 degrees C and 50% relative humidity) for approximately 60 min. This exposure caused sudomotor activation by increasing skin temperature without a marked change in internal temperature. After this period, each subject performed isometric handgrip exercise [15, 30, 45, and 60% maximal voluntary contraction (MVC)] for 60 s. Although esophageal and mean skin temperatures did not change with a rise in exercise intensity and were similar at all exercise intensities, the sweating rate (SR) on the forearm increased significantly (P < 0.05) from baseline (0.094 +/- 0.021 mg. cm(-2). min(-1) at 30% MVC, 0.102 +/- 0.022 mg. cm(-2). min(-1) at 45% MVC, 0.059 +/- 0.009 mg. cm(-2). min(-1) at 60% MVC) in parallel with exercise intensity above exercise intensity at 30% MVC (0.121 +/- 0.023 mg. cm(-2). min(-1) at 30% MVC, 0.242 +/- 0.051 mg. cm(-2). min(-1) at 45% MVC, 0.290 +/- 0.056 mg. cm(-2). min(-1) at 60% MVC). Above 45% MVC, SR on the palm increased significantly from baseline (P < 0.05). Although SR on the forearm and palm tended to increase with a rise in exercise intensity, there was a difference in the time courses of SR between sites. SR on the palm showed a plateau after abrupt increase, whereas SR on the forearm increased progressively during exercise. These results suggest that the increase in SR with the increase in sustained handgrip exercise intensity is due to nonthermal factors and that the magnitude of these factors during the exercise may be responsible for the magnitude of SR.

Adult↗

PubMed1998

Long-term prognostic value of exercise echocardiography compared with exercise 201Tl, ECG, and clinical variables in patients evaluated for coronary artery disease.

BACKGROUND: The accuracy of exercise echocardiography and 201Tl single photon emission computed tomography (SPECT) is similar in the diagnosis of coronary artery disease (CAD). However, comparative data on long-term prognosis are lacking. METHODS AND RESULTS: Clinical variables and exercise, echocardiographic, and 201Tl tomographic parameters were studied in 248 patients (age, 56+/-12 years [mean+/-SD]; 189 men) who underwent simultaneous treadmill exercise 201Tl SPECT and echocardiography. Follow-up was obtained in 225 patients (91%) at a mean of 3.7+/-2.0 years. A total of 64 cardiac events occurred. With the use of stepwise logistic regression, 4 models simulating clinical stress testing scenarios were evaluated in the prediction of all cardiac events, ischemic events, and/or cardiac death. The best clinical models were exercise echocardiography with exercise ECG and exercise 201Tl SPECT with exercise ECG. Both models were comparable in the prediction of cardiac events. For the exercise echocardiography model, exercise wall motion score index and induction of ischemia were the strongest predictors of events with ORs of 2.63 per unit increment (95% CI, 1. 34 to 5.17; P=0.005) and 4.1 (95% CI, 1.32 to 12.79; P=0.015), respectively. For the model with exercise 201Tl SPECT, the strongest predictor was ischemic perfusion defect (OR, 4.93; 95% CI, 1.72 to 14.08; P=0.003). The absence of ST changes during exercise decreased the risk of events. For the prediction of ischemic events and/or cardiac death, echocardiographic and 201Tl parameters were the only predictive variables. CONCLUSIONS: In patients evaluated for CAD, exercise echocardiography and 201Tl combined with ECG variables provide comparable prognostic information and can be used interchangeably for risk stratification.

Adult↗

PubMedDate not supplied

Exercise habits and exercise relapse in persons with non-insulin-dependent diabetes mellitus.

Exercise is widely recognized as a crucial component in the management of non-insulin-dependent diabetes mellitus (NIDDM), but little is known about actual exercise practices in this group. This study investigated exercise habits in 60 persons with NIDDM and 60 nondiabetic significant others. Despite the importance of exercise, most of the persons with NIDDM in our study were not exercising regularly, and the percent of persons exercising regularly was no greater in the diabetic group than in the group of significant others. Although those with NIDDM reported more frequent discussion about exercise with health care professionals, only 25% reported receiving specific guidelines for exercise. Diabetic respondents reported a greater number of relapse or dropout episodes than did the nondiabetic significant others, and relapse was associated with increased guilt. Persons with NIDDM appear to receive recommendations to exercise without instruction on exercise maintenance strategies, resulting in more failed attempts to exercise, and increased guilt. Interventions shown to be effective for increasing exercise maintenance need to be incorporated into the diabetic regimen.

Diabetes Mellitus, Type 2↗

PubMed1998

[Effect of exercise duration on the magnitude and duration of post-exercise hypotension].

PURPOSE: Considering that exercise duration may play a role in post-exercise hypotension, we tested the hypothesis that a prolonged submaximal exercise would lead to a greater and longer blood pressure fall after exercise than a shorter exercise bout. METHODS: Experimental protocol-10 subjects were submitted to two cycle ergometer exercise trials (25 and 45 min) at 50% of VO2 peak. Control protocol-12 subjects rested in the sitting position for 45 min. Blood pressure (BP) was measured before (20 min) and after (90 min) rest or exercise bouts. RESULTS: Systolic BP decreased significantly after exercise and this reduction was greater and lasted longer after 45 min of exercise. Mean and diastolic BP decreased after exercise and they were significantly lower during the 45 min session. Control protocol--no change in BP was observed after resting condition. CONCLUSION: A longer exercise bout leads to a greater and longer post-exercise hypotension.

Adult↗

PubMed1992

[Hypertensive reaction to exercise. Retrospective studies of 1363 consecutive exercise tests].

OBJECTIVE: To study exercise hypertensive reaction and its relation with rest blood pressure, hypertension type and hypertensive cardiac disease. DESIGN: Retrospective study of treadmill exercise testes (ET) performed from January/89 to June/91: (n: 1703). SETTING: Stress tests Laboratory of Cardiology Service of a Military Hospital. METHODS: 1363 consecutive ET of male subjects, performing at least the 3rd stage of the Bruce protocol, were studied. From each ET record were obtained general data, including the reason for test, medication and the rest and exercise blood pressure. Exercise hypertensive reaction was defined as a Bruce protocol 3rd stage systolic blood pressure above 187 mmHg, which corresponds to mean +2SD of 130 normal male subjects previously studied. The Echocardiograms of non-treated hypertensives, obtained less than a month from ET, were reviewed. The diagnosis of borderline or moderate hypertension was base on the clinical records. RESULTS: 1) The 1363 ET included 132 (9.7%) ET to study hypertensive subjects, and 68 of these had hypertensive reaction. 86 ET were performed by non-treated hypertensive subjects, of whom 73 had Echocardiogram. 43 (3.5%) from 1231 ET performed by non-hypertensive subjects also had exercise hypertensive reaction. 2) The left ventricular (LV) mass index of non-treated hypertensive patients had a positive correlation with exercise systolic pressure (r: 0.45; p < 0.001), more important than with rest blood pressure or exercise systolic pressure response; there was a relation with LV wall thickness, but not with internal ventricular dimensions, that was only observed in hypertensive subjects that also had hypertensive reaction to exercise. 3) Exercise systolic blood pressure was usually normal in borderline and elevated in moderate hypertensives (Qui2: 27.249; p < 0.001). 4) Subjects with exercise hypertensive reaction, but not previously diagnosed as hypertensives, were usually true hypertensives. CONCLUSIONS: 1) Hypertensive peaks seem to be an important determinant factor in LV hypertrophy of hypertension, but its influence is felt only above a certain blood pressure threshold; it results on LV concentric type hypertrophy. 2) Exercise systolic blood pressure had a discrimination power of about 80% to separate borderline and moderate hypertensive subjects. 3) All subjects having an exercise hypertensive reaction must be carefully observed, even if their blood pressure at rest is normal, because most of them are true hypertensive patients.

Adult↗

PubMed1994

Exhausting handgrip exercise reduces the blood flow in the active calf muscle exercising at low intensity.

The calf and forearm blood flows (Qcalf and Qforearm respectively), blood pressure, heart rate and oxygen uptake of six men and women were studied during combined leg and handgrip exercise to determine whether a reduction of exercise-induced hyperaemia would occur in the active leg when exhausting rhythmic handgrip exercise at 50% maximal voluntary contraction (MVC) was superimposed upon rhythmic plantar flexion lasting for 10 min at 10% MVC (P10) prior to this combined exercise. The Qcalf and Qforearm were measured by venous occlusion plethysmography during 5-s rests interposed during every minute of P10 exercise and immediately after combined exercise. The muscle sympathetic nerve activity (MSNA) changes were also recorded during leg exercise alone and combined exercise. During plantar flexion performed 60 times.min-1 with a load equal to 10% MVC (P10), Qcalf was maintained at a constant level, which was significantly higher than the resting value (P < 0.001). When rhythmic handgrip contraction at 50% MVC (H50) and P10 were performed simultaneously, the combined exercise was concluded due to forearm exhaustion after a mean of 51.2 (SEM 5.5) s. At exhaustion, Qcalf had decreased significantly from 20.6 (SEM 3.0) ml.100 ml-1.min-1 (10th min during P10 exercise) to 15.3 (SEM) ml.100 ml-1.min-1 (P = 0.001), whereas Qforearm had increased significantly (0.001 < P < 0.01) from 8.6 (SEM 1.9) ml.100 ml-1.min-1 (10th min of P10 exercise) to 26.2 (SEM 3.2) ml.100 ml-1.min-1. The mean blood pressure remained at an almost constant level during the 3rd to 10th min of P10 exercise and increased markedly when H50 was added.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Cardiovascular adjustments to rhythmic handgrip exercise: relationship to electromyographic activity and post-exercise hyperemia.

The purpose of this study was to examine the association among electromyographic (EMG) activity, recovery blood flow, and the magnitude of the autonomic adjustments to rhythmic exercise in humans. To accomplish this, 10 healthy subjects (aged 23-37 y) performed rhythmic handgrip exercise for 2 min at 5, 15, 25, 40, and 60% of maximal voluntary force. Heart rate and arterial blood pressure were measured at rest (control), during each level of exercise, and for 2 min following exercise (recovery). The rectified, filtered EMG activity of the exercising forearm was measured continuously during each level of exercise and was used as an index of the level of central command. Post-exercise hyperemia was calculated as the difference between the control and the average recovery (2 min) forearm blood flows (venous occlusion plethysmography) and was examined as a possible index of the stimulus for muscle chemoreflex activation. Heart rate, arterial pressure, forearm EMG activity, and post-exercise hyperemia all increased progressively with increasing exercise intensity. The magnitudes of the increases in heart rate and arterial pressure from control to exercise were directly related to both the level of EMG activity and the degree of post-exercise hyperemia across the five exercise intensities (delta heart rate vs EMG activity: r = 0.99; delta arterial pressure vs EMG activity: r = 0.99; delta heart rate vs hyperemia: r = 0.99; and delta arterial pressure vs hyperemia: r = 0.98; all p less than 0.01). Furthermore, the level of EMG activity was directly related (r = 0.99) to the corresponding degree of hyperemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1989

Exercise and hypoxia increase sickling in venous blood from an exercising limb in individuals with sickle cell trait.

PURPOSE: The association between sickle cell trait (SCT) and complications related to exercise may be explained if exercise-induced sickling interferes with capillary blood flow and causes tissue ischemia and functional abnormalities. To test this hypothesis, we measured sickling and blood gas values in venous and arterial blood of an exercising limb in subjects with SCT and in controls. SUBJECTS AND METHODS: The study consisted of 15 subjects with hemoglobin AS (SCT group) and 15 subjects with hemoglobin AA (control group). Each performed two maximal arm crank exercise tests, one at 1,270 meters and one at simulated 4,000 meters. RESULTS: At 1,270 meters, axillary venous sickling increased significantly (p less than 0.05) from (mean +/- SD) 1.0 +/- 1.0% at rest to 2.3 +/- 2.6% during peak exercise. At simulated 4,000 meters, sickling increased significantly (p less than 0.001) from 1.5 +/- 1.2% to 8.5 +/- 7.1%. A wide range of sickling during peak exercise was observed (1% to 25%). One minute after exercise at simulated 4,000 meters, venous sickling remained elevated (7.2 +/- 7.8%) despite high levels of oxygen saturation. Arterial sickling (less than 1%) was present in only two subjects. There was no significant difference in oxygen consumption (29.4 +/- 3 versus 30.7 +/- 4 mL/kg/minute) between the subjects with SCT and the controls, nor was there a correlation between exercise performance and sickling (r less than 0.2). CONCLUSION: We conclude that exercise at 1,270 meters slightly, albeit significantly, increased sickling in blood from an exercising limb and that simulated 4,000 meters dramatically potentiated this effect. Sickling in the effluent blood of an exercising limb does not appear to measurably affect overall maximal arm crank exercise performance.

Adult↗

PubMed1988

Exercise haemodynamics and maximal exercise capacity during beta-adrenoceptor blockade in normotensive and hypertensive subjects.

1. The effects of atenolol administration on maximal exercise capacity and exercise haemodynamics have been compared in eight normotensive and eight mildly hypertensive subjects, matched for sex, age, body weight, and maximal oxygen uptake, and familiar with maximal exercise testing. 2. Supine and exercise blood pressure, and exercise total peripheral resistance were significantly higher, and exercise cardiac output was significantly lower in the hypertensive than in the normotensive subjects. 3. Administration of atenolol (1 X 100 mg day-1) for 3 days reduced supine and exercise systolic blood pressure, heart rate, and cardiac output, and increased exercise stroke volume. Supine and exercise diastolic blood pressure and exercise total peripheral resistance were unaffected by atenolol. The effects of atenolol did not differ in the normotensive and the hypertensive subjects. 4. Maximal work load, maximal oxygen uptake, and maximal heart rate were reduced to a similar extent in normotensive and hypertensive subjects during atenolol treatment. 5. It is concluded that there is no difference in the effects of short-term atenolol administration on exercise haemodynamics and maximal exercise capacity in normotensive and mildly hypertensive subjects.

Adrenergic beta-Antagonists↗

PubMed2000

Endurance exercise training attenuates leucine oxidation and BCOAD activation during exercise in humans.

We studied the effects of a 38-day endurance exercise training program on leucine turnover and substrate metabolism during a 90-min exercise bout at 60% peak O(2) consumption (VO(2 peak)) in 6 males and 6 females. Subjects were studied at both the same absolute (ABS) and relative (REL) exercise intensities posttraining. Training resulted in a significant increase in whole body VO(2 peak) and skeletal muscle citrate synthase (CS; P < 0.001), complex I-III (P < 0.05), and total branched-chain 2-oxoacid dehydrogenase (BCOAD; P < 0.001) activities. Leucine oxidation increased during exercise for the pretraining trial (PRE, P < 0.001); however, there was no increase for either the ABS or REL posttraining trial. Leucine oxidation was significantly lower for females at all time points during rest and exercise (P < 0.01). The percentage of BCOAD in the activated state was significantly increased after exercise for both the PRE and REL exercise trials, with the increase in PRE being greater (P < 0.001) compared with REL (P < 0.05). Females oxidized proportionately more lipid and less carbohydrate during exercise compared with males. In conclusion, we found that 38 days of endurance exercise training significantly attenuated both leucine oxidation and BCOAD activation during 90 min of endurance exercise at 60% VO(2 peak) for both ABS and REL exercise intensities. Furthermore, females oxidize proportionately more lipid and less carbohydrate compared with males during endurance exercise.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMedDate not supplied

Exercise, performance and temperature control: temperature regulation during exercise and implications for sports performance and training.

Thermoregulation is an important consideration not only for athletic performance but also for the safety of the athlete. This article presents a broad overview of the mechanisms by which body heat is dissipated in an individual exercising in a hot environment. Particularly emphasised are more recent views of body heat loss mechanisms and the influences of non-thermal inputs, such as effects due to changing blood volume or blood flow distribution. During exercise in a hot environment, metabolic heat produced by the exercising muscles is transported by the circulating blood to the surface of the body where it is released to the environment, either by radiation and convection or by evaporation of sweat. The primary drives for both the increased skin blood flow and increased body sweating are the thermal inputs which are sensed by receptors in the deep body core, with a lesser drive from skin receptors. These thermal signals are integrated in the hypothalamus and proper heat loss responses are effected. When exercise is prolonged, however, and body rehydration is not adequate, the total blood volume may be compromised. In addition, as the core temperature increases during exercise, larger proportions of the blood volume are distributed to the cutaneous vessels, thus effectively reducing cardiac return and central blood volume. During severe exercise, a reduction in cardiac filling may result in a fall in central venous pressure and stimulate baroreceptor vasoconstrictor reflexes. As discussed below, the outputs from these baroreceptors compete with and modify the thermal drives for both the control of the skin blood flow and control of the sweat glands. The effect of high ambient temperatures on exercise performance is most evident in prolonged submaximal exercise. Normally, maximal exercise performance is not altered by high temperatures unless the individual has an elevated deep body temperature before the start of the exercise task. However, submaximal exercise performance is often impaired by high ambient temperatures, but may be improved by programmes of physical training and heat acclimatisation. Both training and heat acclimatisation significantly modify the control systems which regulate skin blood flow and sweating. Only acclimatisation programmes, however, are effective in preventing heat stress during prolonged exercise in hot environments.

Animals↗

PubMed1999

Changes in exercise and post-exercise core temperature under different clothing conditions.

This study evaluates the effect of different levels of insulation on esophageal (Tes) and rectal (Tre) temperature responses during and following moderate exercise. Seven subjects completed three 18-min bouts of treadmill exercise (75% VO2max, 22 degrees C ambient temperature) followed by 30 min of recovery wearing either: (1) jogging shoes, T-shirt and shorts (athletic clothing); (2) single-knit commercial coveralls worn over the athletic clothing (coveralls); or (3) a Canadian Armed Forces nuclear, bacteriological and chemical warfare protective overgarment with hood, worn over the athletic clothing (NBCW overgarment). Tes was similar at the start of exercise for each condition and baseline Tre was approximately 0.4 degree C higher than Tes. The hourly equivalent rate of increase in Tes during the final 5 min of exercise was 1.8 degrees C, 3.0 degrees C and 4.2 degrees C for athletic clothing, coveralls and NBCW overgarment respectively (P < 0.05). End-exercise Tes was significantly different between conditions [37.7 degrees C (SEM 0.1 degree C), 38.2 degrees C (SEM 0.2 degree C and 38.5 degrees C (SEM 0.2 degree C) for athletic clothing, coveralls and NBCW overgarment respectively)] (P < 0.05). No comparable difference in the rate of temperature increase for Tre was demonstrated, except that end-exercise Tre for the NBCW overgarment condition was significantly greater (0.5 degree C) than that for the athletic clothing condition. There was a drop in Tes during the initial minutes of recovery to sustained plateaus which were significantly (P < 0.05) elevated above pre-exercise resting values by 0.6 degree C, 0.8 degree C and 1.0 degree C, for athletic clothing, coveralls, and NBCW overgarment, respectively. Post-exercise Tre decreased very gradually from end-exercise values during the 30-min recovery. Only the NBCW overgarment condition Tre was significantly elevated (0.3 degree C) above the athletic clothing condition (P < 0.05). In conclusion, Tes is far more sensitive in reflecting the heat stress of different levels of insulation during exercise and post-exercise than Tre. Physiological mechanisms are discussed as possible explanations for the differences in response.

Adult↗

PubMed1991

Duration of ST segment depression after exercise-induced myocardial ischemia is influenced by body position during recovery but not by type of exercise.

To assess whether the duration of ischemic ST segment depression after exercise can be modified by changes in body position during recovery or with different types of exercise, 18 patients with chronic stable angina, positive exercise test results, and documented coronary artery disease were prospectively studied. Every patient underwent testing with three different exercise protocols: (1) Bruce (Bruce-standing recovery), (2) abrupt onset of exercise (abrupt), and (3) modified Bruce protocol preceded by a 10-minute warm-up period (warm-up). After exercise test patients recovered in a sitting position. In addition, all patients performed a fourth exercise (Bruce protocol), but this time they recovered in the supine position (Bruce-supine recovery). Time and heart rate-blood pressure product at 1 mm ST segment depression were similar for Bruce-standing recovery, abrupt, and Bruce-supine recovery protocols (5.1 +/- 2, 4.4 +/- 2, and 5.2 +/- 2 minutes and 20.8 +/- 4, 21.3 +/- 4, and 20.4 +/- 4 beats/min x mm Hg x 10(-3), respectively. Heart rate and heart rate-blood pressure product at peak exercise did not differ in Bruce-standing recovery, abrupt, and Bruce-supine recovery. Maximal ST segment depression was -2.0, -1.9, and -2.0 mm with Bruce-standing recovery, abrupt, and Bruce-supine recovery exercise, respectively, and -1.5 mm with warm-up exercise (p less than 0.05). Duration of ST segment depression into recovery was significantly prolonged after Bruce-supine recovery exercise (9.4 + 5 minutes) compared with Bruce-standing recovery, abrupt, and warm-up protocols (6.8 + 3, 5.9 + 4, and 5.0 + 3 minutes, respectively; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1999

Comparison of treadmill exercise echocardiography before and after exercise in the evaluation of patients with known or suspected coronary artery disease.

OBJECTIVES: We sought to compare the feasibility and accuracy of peak treadmill exercise echocardiography versus postexercise echocardiography imaging. BACKGROUND: Although peak exercise echocardiography has been reported for both supine and orthostatic bicycle exercise and has shown higher sensitivity than postexercise imaging, acquiring images at peak exercise with treadmill has not been explored. METHODS: Peak and post-treadmill exercise echocardiography and coronary angiography were performed on 89 patients with known or suspected coronary artery disease. Positive exercise echocardiography was defined as necrosis or ischemic response. Positive coronary angiography was defined as >/=1 diseased vessels (>/=50% luminal narrowing). Images were analyzed in a blind manner by an expert observer. RESULTS: Postexercise images were acquired within 80 seconds after exercise (40 +/- 14). Mean heart rate (bpm) was 139 +/- 22 at peak versus 118 +/- 25 at postexercise imaging (P <.001). Interpretable peak and postexercise images were obtained for all 89 patients. Of the 72 classified as having positive exercise echocardiography, 23 had new regional wall motion abnormality at peak (21 with positive angiography), which resolved at postexercise imaging. Sensitivity was higher with peak than with postexercise imaging (94% vs 73%, P <.001). Specificity was similar (68% vs 79%), as was predictive positive value (92% vs 93%). Negative predictive value was again higher with peak imaging (76% vs 44%, P <.05). Total accuracy was higher with peak imaging (89% vs 74%, P <.05). CONCLUSIONS: Peak treadmill exercise echocardiography is technically feasible and has higher sensitivity and accuracy than post-treadmill exercise echocardiography. Therefore in the clinical setting peak exercise echocardiography should be performed to diagnose ischemia.

Coronary Angiography↗

PubMed1999

The exercise-induced oxidative stress paradox: the effects of physical exercise training.

BACKGROUND: Although physical exercise training is highly recommended, physical exercise causes oxidative stress, which is potentially injurious. This study evaluates this 'exercise paradox' by evaluating the effect of physical exercise on exercise-induced lipid peroxidation. METHODS: Measurement of lipid peroxidation (ie, expired ethane and pentane and plasma malondealdehyde) taken during cardiopulmonary exercise stress testing were compared between a group of 10 cardiac patients who underwent physical exercise training in a cardiac rehabilitation setting and a group of 10 nonexercising cardiac patients. RESULTS: Our findings indicate that physical exercise training increased physical work capacity without a concomitant increase in expired markers of lipid peroxidation (ethane and pentane) and decreased malondealdehyde levels. CONCLUSIONS: Because physical exercise-trained people can perform more intense physical work with less oxidative stress, we conclude that physical exercise training can reduce potential chronic health effects associated with daily activities by contributing to an overall reduction in exercise-induced free radical production.

Adult↗

PubMed1989

Exercise training in patients with chronic heart failure delays ventilatory anaerobic threshold and improves submaximal exercise performance.

We have recently demonstrated that exercise training can induce important hemodynamic and metabolic adaptations in patients with chronic heart failure due to severe left ventricular dysfunction. This study examines the accompanying changes in submaximal exercise performance and the ventilatory response to exercise in these patients. Before and after 16-24 weeks of exercise training, subjects underwent two symptom-limited bicycle exercise tests, one with an incremental graded workload, and one with a constant workload that represented 79 +/- 11% of the pretraining peak oxygen consumption. Breath-by-breath expired gas analysis was performed continuously during each test, and central hemodynamic, leg blood flow, and blood lactate measurements were obtained during the incremental protocol. The ventilatory anaerobic threshold was determined during the incremental exercise study from coplotted breath-by-breath ventilatory data with standard criteria by observers who were unaware of patient identity or training status. As previously reported, exercise training increased peak oxygen consumption by 23% from 16.8 +/- 3.8 to 20.6 +/- 4.7 ml/kg/min and reduced blood lactate levels during submaximal exercise. The training-induced decrease in lactate accumulation was accompanied by a decrease in carbon dioxide production, respiratory exchange ratio, and ventilation during submaximal exercise. The ventilatory anaerobic threshold was delayed from 284 +/- 43 to 352 +/- 91 seconds of exercise (p = 0.02), and it occurred at an increased oxygen consumption (10.1 +/- 1.2 vs. 12.1 +/- 2.6 ml/kg/min, p = 0.01). Exercise duration during the constant workload protocol increased from 938 +/- 410 to 1,429 +/- 691 seconds (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗