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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↗

PubMed2001

Validation of a specific activity questionnaire to estimate exercise tolerance in patients referred for exercise testing.

BACKGROUND: Physical activity and symptom questionnaires have been used as surrogates for exercise testing to estimate a patient's functional capacity and to individualize an exercise testing protocol in accordance with exercise testing guidelines. To validate these approaches, they must be compared with measured oxygen uptake (peak VO (2)). METHODS: Before exercise testing was performed, a brief, self-administered questionnaire (Veterans Specific Activity Questionnaire [VSAQ]) was given to 337 patients referred for exercise testing for clinical reasons. The VSAQ was used to estimate exercise tolerance on the basis of symptoms during daily activities to individualize ramp rates on the treadmill so that the test duration would be approximately 10 minutes. Clinical and demographic variables were added to the VSAQ responses in a stepwise regression model to determine their ability to predict both directly measured peak VO (2) and peak metabolic equivalents (METs) predicted from the treadmill workload. RESULTS: The mean exercise time was 9.6 +/- 3 minutes. Responses to the VSAQ and age were the strongest predictors of both measured and predicted exercise capacity. Small but significant contributions to the explanation of variance in both measured and estimated METs were made by resting heart rate, forced expiratory volume in 1 second expressed as a percentage of normal, exercise capacity predicted for age, and body mass index. The multiple R values from the regression equations for measured and estimated METs were 0.58 and 0.72, respectively. CONCLUSIONS: Estimating a patient's symptoms associated with daily activities along with age are the strongest predictors of a patient's exercise tolerance. The VSAQ, combined with pretest clinical data, predicts the estimated MET value from treadmill speed and grade better than directly measured METs do. When used for estimating a patient's symptom limits to individualize ramp rates on a treadmill, this approach yields an appropriate test duration in accordance with recent exercise testing guidelines.

Activities of Daily Living↗

PubMed2001

Relation between exercise capacity and left ventricular systolic versus diastolic function during exercise in patients after myocardial infarction.

BACKGROUND: It is known that left ventricular systolic function at rest does not correlate well with exercise capacity of patients with heart failure. However, the contribution of left ventricular diastolic dysfunction, especially during exercise, to exercise capacity of cardiac patients remains to be determined. OBJECTIVE: To determine the impact of left ventricular systolic and diastolic function during exercise on exercise capacity of patients with left ventricular dysfunction after myocardial infarction. METHODS: A symptom-limited exercise test was performed with measurements for hemodynamics and uptake of oxygen (Vo2) of 26 men who had previously suffered myocardial infarction. These patients were divided into two groups according to their peak Vo2 (group 1 with peak Vo2 > or = 16 ml/kg per min, n= 13; and group 2 with peak Vo2 < 16 ml/kg per min, n= 13). Pulmonary arterial pressure, left ventricular and systemic arterial pressure, and cardiac output were measured at rest and during exercise. RESULTS: At rest, there was no difference between the two groups in terms of hemodynamic parameters except for minimal dP/dt, minimal left ventricular pressure (LVP) and time constant for decay of left ventricular pressure (tau). During peak exercise, cardiac output, left ventricular end-diastolic pressure (EDP), minimal dP/dt, minimal LVP, and tau for the two groups were significantly different. Furthermore, peak Vo2 was significantly correlated with T, minimal LVP, minimal dP/dt, EDP, and maximal dP/dt during peak exercise for the whole group of patients. CONCLUSION: Left ventricular diastolic function during exercise, i.e. diastolic reserve, may be an important determinant of exercise capacity of patients with left ventricular dysfunction after myocardial infarction.

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↗

PubMed2002

Exercise-induced oxyhaemoglobin desaturation, ventilatory limitation and lung diffusing capacity in women during and after exercise.

Arterial haemoglobin saturation during exercise in healthy young women [eight subjects mean (SEM) age 20.8 (1.8) years] was measured to confirm the theory that young women experience exercise-induced arterial hypoxaemia (EIAH) at a lower relative percentage of maximal oxygen uptake (VO(2max)) than has been documented in their male counterparts. To determine if flow limitation [the percentage of the tidal volume ( V(T)) that met or exceeded the boundary established by multiple maximal expiratory manoeuvres] and/or post-exercise lung diffusing capacity are linked to EIAH in women, and to investigate the influence of exercise intensity and duration on post-exercise carbon monoxide lung diffusing capacity ( D(L, CO)), these parameters were measured during and after three exercise tests (incremental test until exhaustion, 5 km run and 5 km run with sprint). All subjects experienced physiologically significant EIAH (a fall of more than 3% in oxygen saturation of arterial blood from levels at rest) and seven subjects experienced flow limitation during the VO(2max) protocol [mean (SD) 12.2 (8.8)% of V(T)]. Even though there was no significant relationship between aerobic capacity and the degree of flow limitation ( r=0.33, P>0.05), the flow limitation was related to absolute ventilation in the subjects studied ( r=0.82, P<0.05). There was no significant relationship between decrements in post exercise D(L, CO) and EIAH ( r=0.05, P>0.05), however there was a strong correlation between the extent of flow limitation (% of V(T)) and EIAH ( r=0.71). Significant decreases in D(L, CO) lasted for up to 16 h after each of the exercise tests ( P<0.05) and lasted for a further 8 h after the maximal test ( P<0.05). Exercise intensity was the main contributing factor to the observed decreases in post-exercise D(L, CO) with the percentage of VO(2max) attained during the various tests being significantly related to the fall in D(L, CO) for 1, 2, 3, 16 and 24 h after exercise ( P<0.05). As the appearance of flow limitation closely coincided with the appearance of EIAH, the results from the present study suggest that flow limitation is a contributing factor to EIAH in women although the exact mechanism remains unclear.

Adult↗

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↗

PubMed2000

Oxygen uptake efficiency slope: an index of exercise performance and cardiopulmonary reserve requiring only submaximal exercise.

OBJECTIVES: We sought to evaluate, in adults, the efficacy of the Oxygen Uptake Efficiency Slope (OUES), an index of cardiopulmonary functional reserve that can be based upon a submaximal exercise effort. BACKGROUND: Maximal oxygen uptake (VO2,max), the most reliable measure of exercise capacity, is seldom attained in standard exercise testing. The OUES, which relates oxygen uptake to total ventilation during exercise, was proposed by Baba and coworkers (7) in a study of pediatric cardiac patients. They felt this submaximal index of cardiopulmonary reserve might be more practical than VO2max and more appropriate than the commonly used peak oxygen consumption (VO2 peak). METHODS: Treadmill exercise tests with simultaneous respiratory gas measurement were performed in 998 older subjects free of clinically recognized cardiovascular disease and 12 male patients with congestive heart failure. During incremental exercise, oxygen uptake was plotted against the logarithm of total ventilation, and the OUES was determined. RESULTS: The OUES, when calculated only from the first 75% of the exercise test, differed by 1.9% from the OUES calculated from 100% of exercise time in subjects with a peak respiratory exchange rate > or =1.10. On serial tests the OUES was less variable than exercise duration or VO2 peak. It correlated strongly with VO2max, with forced expiratory volume in 1 s and negatively with a history of current smoking. The OUES declined linearly with age in both women and men. A small sample of patients with congestive heart failure had OUES values much lower than those of older subjects without cardiovascular disease. CONCLUSIONS: The OUES is an objective, reproducible measure of cardiopulmonary reserve that does not require a maximal exercise effort. It integrates cardiovascular, musculoskeletal and respiratory function into a single index that is largely influenced by pulmonary dead space ventilation and exercise-induced lactic acidosis.

Aged↗

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↗

PubMed1992

Effects of arotinolol on exercise capacity and humoral factors during exercise in normal subjects.

A placebo-controlled, double-blind crossover study was undertaken in 10 normal subjects to examine the effects of arotinolol (10 mg bid), a nonselective beta blocker with alpha-blocking activity, on exercise capacity and hormone levels during exercise after a 2-week treatment period. Maximal oxygen uptake (VO2 max) and blood lactic acid concentration (LA) were measured during progressive exercise testing. An exercise intensity equivalent to 4 mmol/l of LA was used for the constant workload exercise test. Humoral factors were measured after 20 minutes of constant workload exercise. The administration of arotinolol significantly decreased systolic blood pressure and heart rate at rest and during exercise, but diastolic blood pressure did not change. No significant difference was found between arotinolol and placebo with regard to VO2 max and maximal workload. Plasma renin activity (PRA), aldosterone (PAC), and norepinephrine (NE) levels at rest and during exercise did not differ between the two treatments. In contrast, plasma epinephrine (EN) levels at rest and during exercise were significantly greater with arotinolol. Atrial natriuretic peptide (ANP) at rest did not differ between the two treatments. However, exercise caused a significant increase in ANP after arotinolol treatment. These findings suggest that arotinolol decreases blood pressure and heart rate without affecting exercise capacity.

Adrenergic beta-Antagonists↗

PubMed1996

Differential cardiorespiratory response to combined exercise with different combinations of forearm and calf exercise.

The purpose of this study was to examine whether cardiorespiratory responses to combined rhythmic exercise (60 contractions.min-1) was affected by different combinations of upper and lower limb exercise in seven healthy women. Six different rhythmic exercises were compared: 6-min rhythmic handgrip at 10% of isometric maximal voluntary contraction (MVC) (H10); 6-min rhythmic plantar flexion at 10% MVC (P10); exhausting rhythmic handgrip at 50% MVC (H50); exhausting rhythmic plantar flexion at 50% MVC (P50); H50 was added to P10 (P10H50); and P50 was added to H10 (H10P50). Exercise duration, after handgrip was combined with plantar flexion (P10H50), was shorter than that of H50, although the exercise duration of H10P50 was not significantly different from P50. No significant difference was found between the difference from rest in oxygen uptake (delta VO2) during H10P50 and the sum of delta VO2 during H10 and P50. Also, the differences from rest in forearm blood flow (delta FBF) and calf blood flow (delta CBF) during H10P50 were not significantly different from delta FBF in H10 and from delta CBF in P50. In contrast, delta VO2 in P10H50 was lower than the sum of delta VO2 in P10 and H50 (P < 0.05), and delta FBF in P10H50 was lower than that in H50 (P < 0.05), while delta CBF was not significantly different between P10H50 and P10. The changes in heart rate from rest (delta HR) during the combined exercises were lower than the sums of delta HR in the corresponding single exercises (P < 0.05). These results demonstrated an inhibitory summation of several cardiorespiratory responses to combined exercise resulting in a reduction in exercise performance which would seem to occur easily when upperlimb exercise is added to lower limb exercise.

Adult↗