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PubMed1987

Long-term antihypertensive therapy with beta-blockers: submaximal exercise capacity and metabolic effects during exercise.

The effects of long-term (6 months) antihypertensive treatment with three different types of beta-blockers (propranolol, nonselective without ISA; pindolol, nonselective with ISA; metoprolol, beta 1-selective without ISA) on submaximal exercise capacity and metabolic variables during submaximal endurance exercise were studied in seven subjects with essential hypertension. Exercise tests were performed on a bicycle ergometer at 70% of estimated VO2 max. Similar reductions of resting and exercise blood pressure and exercise heart rate were obtained with the three beta-blockers. Exercise time was significantly reduced by all three beta-blockers during chronic antihypertensive therapy. The reduction tended to be more pronounced after 5-6 months of treatment than after 1 week (P = 0.06). During exercise, the plasma glycerol and nonesterified fatty acid concentrations were reduced. Plasma glucose concentration was reduced at the end of the exercise test during propranolol treatment only. Plasma lactate concentrations tended to be increased, but the difference was significant during pindolol treatment only. Oxygen uptake tended to decrease and respiratory exchange ratio to increase. Plasma potassium concentrations during exercise were significantly increased with all three beta-blockers. The effects on the metabolic variables during exercise were similar after 1 week and during long-term (20/24 weeks) beta-blocker treatment. The study shows that submaximal endurance exercise capacity is impaired in patients with essential hypertension on beta-blocker therapy and that the impairment is maintained during long-term antihypertensive beta-blocker treatment.

Adrenergic beta-Antagonists↗

PubMed1992

Predicting cardiac mortality after uncomplicated myocardial infarction by exercise radionuclide ventriculography and exercise-induced ST segment elevation.

In 183 consecutive patients with recent, uncomplicated myocardial infarction, the following variables were associated with 4-year cardiac death: haemodynamic decompensation with exercise (P = 0.01), left ventricular ejection fraction at rest (P = 0.004) and at peak exercise (P = 0.003), persistent ST segment elevation at rest in the area of infarction = (P = 0.004), exercise-induced ST segment elevation (P = 0.02), and late aneurysmal evolution (P = 0.01). Exercise left ventricular ejection fraction was the sole variable selected by Cox regression analysis as an independent predictor of cardiac death. In 40 patients with ST segment elevation at rest, left ventricular ejection fraction was 42 +/- 17% at rest and 40 +/- 18% at peak exercise, versus 52 +/- 12% and 52 +/- 14% in the remaining patients (both P less than 0.01). Among these 40, 16 (all with anterior infarction) also had exercise-induced ST segment elevation; their ejection fraction was 32 +/- 13% at rest, 30 +/- 13% during exercise, versus 53 +/- 15% and 53 +/- 15% in 129 patients with no ST segment elevation either at rest, or during exercise (both P less than 0.01). The 4-year risk of death was 20% in the former 40 patients, 36% in the latter 16, while in the complete absence of ST segment elevation, such risk was 3%. All 14 patients with ST segment elevation only during exercise were alive after 4 years: their left ventricular ejection fraction was 47 +/- 12% at rest, 45 +/- 13% with exercise. ST segment elevation was associated with late aneurysmal evolution but not with exercise-induced ischaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Dyspnea↗

PubMed2004

Construction of exercise attitude questionnaire-18 to evaluate patients' attitudes toward exercises.

The importance of exercise for health and the long-term management of various diseases is now well documented and established. However, the challenge is the lack of patient compliance to exercises, which is true for almost all diseases, from acute back pain to chronic arthritis. One of the factors for compliance is the perception that exercises are effective in ameliorating unpleasant symptoms. Precisely, people's perception and their attitude towards exercises matter the most in determining the treatment outcome in such conditions. Unfortunately, the psychology of exercise initiation and adherence in the patient population is seriously under-researched. Recent literature has identified the need to consider various similar factors like motivation, barriers to exercise, exercise-related beliefs, attitudes, and the formulation of self-perceptions and self-identity towards exercises. However, no good instrument exists that is sensitive and standardized to evaluate people's attitude towards exercises, which is fundamental and crucial in determining the final outcome of exercise-treatable diseases. Hence we have attempted to design a questionnaire to 'evaluate the level of people's attitude towards exercises'.

Attitude↗

PubMed1998

Abnormal neurohumoral responses to exercise in patients with heart disease: inhibition of an increase in endothelin-1 production during exercise.

We have reported that the plasma endothelin-1 (ET-1) level is significantly increased by exercise in healthy athletes and that it is elevated in the circulation of the non-working leg but not the working leg, suggesting that ET-1 plays an important role in redistribution of blood during exercise. This study was designed to compare alterations of neurohumoral substances by exercise in normal subjects and patients with heart disease. Study patients comprised three groups: eight patients with congestive heart failure (CHF) due to Ebstein's anomaly or single-ventricle heart after Fontan operation; six patients with complete transposition of the great arteries (TGA) after an anatomic surgical correction who may be candidates for ischemic heart disease; and five age-matched normal subjects. All patients were in New York Heart Association functional class I. All subjects performed symptom-limited treadmill exercise. It is suggested that patients with CHF or TGA have a manifest or latent exercise intolerance, respectively. In failed to increase plasma ET-1 level, although it caused a greater increase in norepinephrine, angiotensin II, and arginine vasopressin than in the controls. Exercise also caused a delay in the increased response of plasma ET-1 levels in patients with TGA after an anatomic surgical repair. On the other hand, plasma brain natriuretic peptide (BNP) level was augmented by exercise in patients with CHF and patients with TGA but not in the controls. The present results suggest that an increase in ET-1 production during exercise is absent in patients with heart disease. The mechanisms of inhibition of ET-1 production during exercise in patients with heart disease remain to be elucidated. However, the present study suggests that ET-1 plays an important role in redistribution of blood during exercise, and proposes the possibility that failure of an increase in ET-1 production results in exercise intolerance in patients with heart disease.

Child↗

PubMed1998

Efficiency and costs of medical exercise therapy, conventional physiotherapy, and self-exercise in patients with chronic low back pain. A pragmatic, randomized, single-blinded, controlled trial with 1-year follow-up.

STUDY DESIGN: A multicenter, randomized, single-blinded controlled trial with 1-year follow-up. OBJECTIVES: To evaluate the efficiency of progressively graded medical exercise therapy, conventional physiotherapy, and self-exercise by walking in patients with chronic low back pain. SUMMARY AND BACKGROUND DATA: Varieties of medical exercise therapy and conventional physiotherapy are considered to reduce symptoms, improve function, and decrease sickness absence, but this opinion is controversial. METHODS: Patients with chronic low back pain or radicular pain sick-listed for more than 8 weeks and less than 52 weeks (Sickness Certificate II) were included. The treatment lasted 3 months (36 treatments). Pain intensity, functional ability, patient satisfaction, return to work, number of days on sick leave, and costs were recorded. RESULTS: Of the 208 patients included in this study, 71 were randomly assigned to medical exercise therapy, 67 to conventional physiotherapy, and 70 to self-exercise. Thirty-three (15.8%) patients dropped out during the treatment period. No difference was observed between the medical exercise therapy and conventional physiotherapy groups, but both were significantly better than self-exercise group. Patient satisfaction was highest for medical exercise therapy. Return to work rates were equal for all 3 intervention groups at assessment 15 months after therapy was started, with 123 patients were back to work. In terms of costs for days on sick leave, the medical exercise therapy group saved 906,732 Norwegian Kroner (NOK) ($122,531.00), and the conventional physiotherapy group saved NOK 1,882,560 ($254,200.00), compared with the self-exercise group. CONCLUSIONS: The efficiency of medical exercise therapy and conventional physiotherapy is shown. Leaving patients with chronic low back pain untampered poses a risk of worsening the disability, resulting in longer periods of sick leave.

Activities of Daily Living↗

PubMed1997

Influence of exercise-induced plasma volume changes on the interpretation of biochemical data following high-intensity exercise.

OBJECTIVE: To assess the effects that exercise-induced plasma volume changes (PVCs) have on the interpretation of biochemical and hormonal parameters in the blood of athletes after high-intensity exercise. It was hypothesized that two unrelated high-intensity exercise protocols, performed by two separate subject groups each using different exercise modes, would result in similar percentage changes in plasma volume (% delta PV). It was further hypothesized that the % delta PV, measured in both protocols, would comparably influence the interpretation of biochemical variables measured following exercise. DESIGN: An experimental before-after trial on volunteers was performed. Two different exercise modes employing two different high-intensity acute exercise protocols were investigated. Eight male swimmers performed an interval training session (ITS) consisting of 15 x 100-m freestyle efforts at 95% of their maximal exercise intensity, and eight male runners performed a multistage discontinuous treadmill test (MSD) to volitional exhaustion. SETTING: The Human Performance Laboratory at the Department of Human Movement at the University of Western Australia. MAIN OUTCOME MEASURES: Blood samples obtained before, immediately after, and 30, 60, and 120 min during recovery were analyzed for plasma volume changes, urea, uric acid, creatinine, albumin, calcium, iron, transferrin, testosterone, cortisol, and sex hormone-binding globulin (SHBG). MAIN RESULTS: The ITS and MSD protocols produced similar and significant alterations (p < 0.01) in plasma volume. Both protocols also elicited significant fluctuations (p < 0.01) in the concentration of most of the parameters measured (excluding iron). When albumin, transferrin, testosterone, and SHBG values were adjusted for the significant % delta PV, their concentrations did not change over the experimental period, suggesting that the changes in measured concentration of these parameters may be, in part, due to changes in plasma volume. However, urea, uric acid, creatinine, calcium, and cortisol, when corrected for % delta PVC, still demonstrated significant changes (p < 0.01). CONCLUSIONS: It is recommended, when sampling biochemical and hormonal parameters in blood following an acute bout of exercise, that corrections for PVCs should be conducted. Apparent changes in blood solutes may reflect PVCs. PVCs should be taken into consideration when interpreting results regardless of exercise protocol and exercise mode performed.

Blood Chemical Analysis↗

PubMed2005

Postprandial triacylglycerol uptake in the legs is increased during exercise and post-exercise recovery.

Six young, healthy male subjects were each studied in two experiments: (1) during resting conditions before and for 360 min after a meal (54% of energy as carbohydrate, 30% of energy as lipid, and 16% of energy as protein) comprising 25% of their total daily energy intake (M-->R); and (2) while exercising on a cycle ergometer for 60 min at 50% of the peak oxygen consumption commencing 60 min after the meal (M-->E) and then for another 240 min. Regional metabolism was measured by Fick's Principle in a leg and in the splanchnic tissue. The combination of food intake and exercise led to increased plasma triacylglycerol (TAG) uptake and clearance in the exercising legs immediately and for at least 4 h post-exercise, while food intake per se did not change leg plasma TAG uptake or clearance for up to 6 h. It is hypothesized that the effect of exercise on leg plasma TAG metabolism is a result of capillary recruitment leading to exposure of the plasma lipoprotein particles to a larger amount of active LPL. In spite of the increased TAG uptake in the exercising legs the arterial plasma TAG concentration had a tendency to increase faster during exercise after a meal than during rest, but it also decreased faster implying that the total lipaemic response was the same whether exercise was performed or not. The amount of lipid taken up in the legs was higher than could be accounted for by whole body lipid oxidation during post-exercise recovery, indicating accumulation of lipid in skeletal muscle in this period. Neither food intake alone nor the combination of food and exercise affected the splanchnic net balance of TAG. Finally, there is an additive effect of exercise and food intake on splanchnic net glucose balance.

Adult↗

PubMed1998

Exercise-induced hyperthermia and hormonal responses to exercise.

Changes in plasma hormonal concentrations during exercise have been ascribed to the type, duration, and intensity of exercise, physical fitness of subjects, oxygen availability and debt, and acid-base balance. However, relatively few studies have examined the possible role of exercise-induced hyperthermia. This paper reviews previous studies on this subject and describes a series of experiments carried out in our laboratories to define the role of changes in body temperature in the release of hormones during exercise. In a first series of experiments, we studied the relationship between thermoregulatory and growth hormone responses to severe exercise at 23 degrees C for 2 h in fit euhydrated subjects, controlling the core temperature increase to a maximum of 40 degrees C by varying wind speed. Exponential relationships were found between increases in core temperature and plasma growth hormone, prolactin, and catecholamines during exercise, suggesting the existence of a thermal threshold for stimulation of hormonal release during exercise. The effect of endurance exercise with and without a thermal clamp (immersion in cold and warm water) on hormonal and leukocyte responses was examined. Again, a significant exponential relationship was found between increases in core temperature and hormonal responses. Thermal clamping significantly diminished the hormonal and the leukocytic responses to exercise, suggesting that an exercise-induced thermal threshold of approximately 38 degrees C exists where hormonal responses are observed. Therefore, core temperature increases may be integrated in the controlling system of hormonal and leukocytic responses to exercise.

Body Temperature↗

PubMed2004

Effect of prior multiple-sprint exercise on pulmonary O2 uptake kinetics following the onset of perimaximal exercise.

We hypothesized that the metabolic acidosis resulting from the performance of multiple-sprint exercise would enhance muscle perfusion and result in a speeding of pulmonary oxygen uptake (VO2)kinetics during subsequent perimaximal-intensity constant work rate exercise, if O2 availability represented a limitation to VO2 kinetics in the control (i.e., no prior exercise) condition. On two occasions, seven healthy subjects completed two bouts of exhaustive cycle exercise at a work rate corresponding to approximately 105% of the predetermined Vo2 peak, separated by 3 x 30-s maximal sprint cycling and 15-min recovery (MAX1 and MAX2). Blood lactate concentration (means +/- SD: MAX1: 1.3 +/- 0.4 mM vs. MAX2: 7.7 +/- 0.9 mM; P < 0.01) was significantly greater immediately before, and heart rate was significantly greater both before and during, perimaximal exercise when it was preceded by multiple-sprint exercise. Near-infrared spectroscopy also indicated that muscle blood volume and oxygenation were enhanced when perimaximal exercise was preceded by multiple-sprint exercise. However, the time constant describing the primary component (i.e., phase II) increase in VO2 was not significantly different between the two conditions (MAX1: 33.8 +/- 5.5 s vs. MAX2: 33.2 +/- 7.7 s). Rather, the asymptotic "gain" of the primary Vo2 response was significantly increased by the performance of prior sprint exercise (MAX1: 8.1 +/- 0.9 ml.min(-1).W(-1) vs. MAX2: 9.0 +/- 0.7 ml.min(-1).W(-1); P < 0.05), such that VO2 was projecting to a higher "steady-state" amplitude with the same time constant. These data suggest that priming exercise, which apparently increases muscle O2 availability, does not influence the time constant of the primary-component VO2 response but does increase the amplitude to which VO2 may rise following the onset of perimaximal-intensity cycle exercise.

Adaptation, Physiological↗

PubMed1998

Comparison of S-T segment/heart rate slope with exercise thallium imaging and conventional S-T segment criteria in detecting coronary artery disease: effect of exercise level on accuracy.

The S-T segment/heart rate (ST/HR) slope has been proposed as a more accurate electrocardiographic criterion for the diagnosis of coronary artery disease, but studies comparing the diagnostic value of the ST/HR slope with exercise thallium imaging are scant. The aims of this study were to assess the diagnostic accuracy of the ST/HR slope, conventional S-T segment criteria and exercise thallium imaging in detecting coronary artery disease and to evaluate the effect of exercise level on the sensitivity and specificity of these three techniques. Ninety consecutive patients underwent treadmill testing and exercise thallium single-photon emission computed tomography (SPECT) simultaneously. All 90 patients also underwent coronary angiography within 1 month of the exercise test. We found that exercise thallium SPECT had a significantly higher diagnostic accuracy than either the ST/HT slope or conventional S-T segment criteria (thallium imaging 82%, ST/HR slope 67%, conventional S-T segment criteria 63%). The overall accuracy of the ST/HR slope was slightly but insignificantly greater than conventional S-T segment criteria (ST/HR slope 67%, conventional S-T segment criteria 63%; p = 0.639). In 50 patients with a lower exercise level, defined as not achieving 85% of their maximal predicted heart rate, the accuracy of the ST/HR slope was insignificantly greater (ST/HR slope 72%, conventional S-T segment criteria 66%; p = 0.517). In 40 patients with adequate exercise, the accuracy rate was the same (60%) for both the ST/HR slope and conventional S-T segment criteria. We conclude that exercise thallium imaging is more accurate than the ST/HR slope in diagnosing coronary artery disease and that the accuracy of the ST/HR slope is marginally better than conventional S-T segment criteria only in patients with a lower exercise level, and not in those with adequate exercise.

Cardiac Catheterization↗

PubMed1986

The effect of indomethacin on exercise-induced bronchoconstriction and refractoriness after exercise.

Exercise causes bronchoconstriction in asthmatic subjects, which is usually followed by a refractory period during which exercise of the same intensity will cause less bronchoconstriction. This study examined the role of contractile prostaglandins in the initial bronchoconstriction after exercise and the role of inhibitory prostaglandins in the refractoriness after exercise. Subjects were pretreated with indomethacin, 50 mg twice daily, on 1 occasion or placebo on 2 occasions for 3 days. This was followed by 2 exercise challenges on a bicycle ergometer at least 30 min apart. Indomethacin did not alter the initial bronchoconstriction after exercise. The maximal fall in FEV1 after the first exercise challenge after placebo was 0.67 +/- 0.17 L and 0.68 +/- 0.17 L, and after indomethacin it was 0.67 +/- 0.12 L. Indomethacin, however, did prevent refractoriness after exercise. The maximal fall in FEV1 after the second exercise challenge after placebo was 0.31 +/- 0.06 L and 0.36 +/- 0.12 L, and after indomethacin it was 0.64 +/- 0.12 L. These results indicate that indomethacin pretreatment does not alter bronchoconstriction after exercise, and they also indicate that indomethacin pretreatment prevents refractoriness after exercise in asthmatic subjects.

Adult↗

PubMed1998

Differentiating syndrome X from coronary artery disease by treadmill exercise test in patients with chest pain and exercise-induced myocardial ischemia.

Even though the underlying mechanisms of myocardial ischemia may be different, it is difficult to differentiate syndrome X from coronary artery disease (CAD) by means of the treadmill exercise test in elderly patients with chest pain and exercise-induced myocardial ischemia. One hundred sex- and age-matched patients-42 with syndrome X and 58 with CAD-were studied. Another 10 subjects with atypical chest pain, negative treadmill exercise test, and normal-appearing coronary angiograms served as controls. We evaluated the difference in exercise performance between patients with syndrome X and CAD, and the treadmill exercise test was undertaken with modified Bruce protocol within 2 weeks before coronary angiography. Parameters including time to 1 mm ST segment depression (STD), exercise duration (ED), heart rate (HR), systolic blood pressure, rate-pressure product (RPP), and percentage of age-predicted maximum HR (% HR) at different stages of the test were measured and then compared among the three groups of patients. Compared with CAD patients, syndrome X patients had significantly higher HR, % HR, and RPP at the time of 1 mm STD and at peak exercise. The time to 1 mm STD and ED were longer in syndrome X than in CAD patients. However, ED was shorter and HR, % HR, and RPP at peak exercise were similar in syndrome X patients as compared with control subjects. The new criterion of combined ED (> or =315 seconds) and RPP at peak exercise (> or =24,000 beats x mmHg/min) was found to be highly specific (86%) and moderately sensitive (64%) in differentiating syndrome X from CAD patients. The positive likelihood ratio for this criterion was 4.57 and negative likelihood ratio was 0.42. In conclusion, syndrome X patients had better exercise performance than CAD patients, but less ED and similar workload when compared with control subjects. The new criterion proposed in this study may provide a quick and simple way to differentiate syndrome X from CAD in a group of aged and predominantly male patients with chest pain and positive treadmill exercise test.

Adult↗

PubMed2005

Exercise slips in high-risk situations and activity patterns in long-term exercisers: an application of the relapse prevention model.

BACKGROUND: Key factors in successful long-term exercise maintenance are not well understood. The Relapse Prevention Model (RPM) may provide a framework for this process. PURPOSE: The purpose of this study was to examine the relationships among characteristics of exercise high-risk situations, components of the RPM relevant to exercise slips, and follow-up exercise outcomes in long-term community exercisers. METHODS: We obtained long-term exercisers' (N=65) open-ended responses to high-risk situations and ratings of obstacle self-efficacy, guilt, and perceived control. High-risk situation characteristics, cognitive and behavioral coping strategies, and exercise outcomes were examined. RESULTS: High-risk situation characteristics included bad weather, inconvenient time of day, being alone, negative emotions, and fatigue. Being alone was associated with lower incidence of exercise slip. Positive cognitive coping strategies were most commonly employed and were associated with positive exercise outcome for both women and men. Guilt and perceived control regarding the high-risk situation were associated with exercise outcomes at follow-up, but only among the men (n=28). CONCLUSIONS: Findings confirm and extend previous work in the application of the RPM in examining exercise slips and relapse. Measurement issues and integration approaches from the study of relapse in addiction research are discussed.

Activities of Daily Living↗

PubMed1993

[A study on the primary prevention of essential hypertension (1). Evaluation of blood pressure response during exercise and effect of habitual exercise].

Hypertension is one of the risk factors of cardiovascular diseases, which are widely prevalent maladies that result in burdensome medical expenditures. Therefore, it is important to explore primary preventive measures for hypertension. Until recently, it was thought that exercise was a risk factor for hypertension, but recent reports have suggested that low-intensity physical training actually lowers blood pressure. However, habitual physical exercise has still not been clearly proven to prevent the development of hypertension. To clarify this point, one must first establish a method for predicting hypertension and second examine the possibility of preventing the development of hypertension by changing the subject's environment. In this study we have investigated a method for predicting hypertension by classifying blood pressure responses to increasing exercise intensity and the effect of habitual exercise on blood pressure response. This study was composed of three experiments. Experiment one involved female students (n = 42) and experiment two, male students (n = 38), in whom blood pressure response rates during exercise were recorded. In experiment three, the same group of female students (n = 23) was subjected to training in order to chart its effects on blood pressure response, both while exercising and while at rest. The exercises were performed with a bicycle ergometer in an upright position. There were four different degrees of work intensity. Blood pressure was measured using the auscultation method, with Riva-Rocci mercury measured by the same investigator. High blood pressure responses at rest were noted among some normotensive female and male students. The systolic blood pressure responses during the peddling exercise showed significant individual differences at the lowest work load; the distribution of the increment of the systolic blood pressure ratio at the lowest work load against the increment while resting showed two peaks. This result suggests that this increment ratio is an important variable related to the prediction of hypertension. The increment ratio showed no significant change in female students after three months of aerobic exercise. The high-response group showed high readings of the TPR indicator (MBP/VO2). Aerobic training was shown to be effective in significantly lowering the TPR indicator both at rest and during exercise. This result suggests that habitual exercise may contribute to preventing the development of hypertension.

Adult↗

PubMed2005

Testosterone and endurance exercise: development of the "exercise-hypogonadal male condition".

During the last 30 years a large number of research studies have been conducted examining reproductive endocrine dysfunction in exercising women. The number of similar studies examining men is still relatively small. Nevertheless, an increasing amount of research studies in men indicate endurance exercise training has significant effects upon the major male reproductive hormone, testosterone, and the hypothalamic-pituitary-testicular axis that regulates reproductive hormones. This review article addresses one reproductive endocrine dysfunction found in exercising men, what has been deemed the "exercise-hypogonadal male condition". Specifically, men with this condition exhibit basal (resting-state) free and total testosterone levels that are significantly and persistently reduced. The exact physiological mechanism inducing the reduction of testosterone is currently unclear, but is postulated to be a dysfunction (or perhaps a readjustment) within the hypothalamic-pituitary-testicular regulatory axis. The time course for the development of the "exercise-hypogonadal condition" or the threshold of exercise training necessary to induce the condition remains unresolved. The potential exists for these reduced testosterone levels within the exercise-hypogonadal male to disrupt and be detrimental to some anabolic or androgenic testosterone-dependent physiological processes. Unfortunately, extremely few research studies have addressed whether such processes are affected, and thus findings are inconclusive. Conversely, the alterations in testosterone levels brought about by endurance exercise training have the potential for cardiovascular protective effects and thus could be beneficial to the health of these men. Current evidence suggests this condition is limited to men who have been persistently involved in chronic endurance exercise training for extended periods of time (i.e., years). Many questions, however, regarding the male reproductive endocrine adaptive process to exercise and exercise training remain unanswered, necessitating the need for further research on this topic.

Cumulative Trauma Disorders↗

PubMedDate not supplied

Noninvasive prediction of restenosis after coronary angioplasty: a head to head comparison among exercise ECG, dipyridamole and exercise thallium scintigraphy.

Restenosis remains the main limitation of percutaneous transluminal coronary angioplasty (PTCA). Since it seems likely that restenosis not severe enough to induce ischemia may be better detected with pharmacological testing than with exercise, we investigated whether dipyridamole thallium scintigraphy is better than exercise-electrocardiogram and exercise-thallium in predicting restenosis after PTCA. Noninvasive tests and re-angiography were performed in 61 consecutive patients, 5-6 months after successful single vessel PTCA. Detection of vessel stenosis greater than or equal to 50% was used as angiographic criteria for restenosis. Exercise-induced angina, ST segment depression greater than or equal to 1 mm at exercise-electrocardiogram and reversible perfusion defects in the area supplied by the dilated vessel, during either dipyridamole and exercise-thallium, were considered noninvasive abnormal responses. The overall restenosis rate was 41% (25/61). Angina was the most specific (97%) of all criteria for restenosis, but also one of the least sensitive (40%), slightly better than exercise-ECG (24%). Exercise-thallium had lower sensitivity (72% vs 88%, p less than 0.05) and negative predictive value (82% vs 91%, p less than 0.05) than dipyridamole-thallium. In patients positive at both exercise-thallium and dipyridamole-thallium testing, mean stenosis at follow-up was more severe (73 +/- 23%) than in patients with positive dipyridamole-thallium and negative exercise-thallium (55 +/- 26%) results, but the difference did not reach statistically significant levels. For these reasons, dipyridamole-thallium seems to be an acceptable alternative to exercise thallium to follow patients after initially successful PTCA.

Aged↗

PubMed2002

Pituitary-adrenal and pituitary-thyroid hormone responses during exercise-cold exposure after 7 days of exhaustive exercise.

BACKGROUND: After several days of exhaustive exercise in mild-warm environments, cutaneous vasoconstrictor responses to cold exposure are less effective in conserving body heat than in the rested condition. Hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid axes hormones could mediate this response since they may affect vasoconstriction. The effects of exertional fatigue on pituitary-adrenal hormones and thyroid hormone responses to exercise-cold stress are unknown. HYPOTHESIS: We hypothesized that 7 consecutive days of exercise would decrease adrenocorticotropin (ACTH) and cortisol, while elevating thyroid stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4) and that these hormones would be related to a blunted vasoconstrictor response to cold. METHODS: Nine male volunteers walked, completely wetted, for up to 6 h in 5 degrees C air, when rested (day 0, control) and after 7 consecutive days (day 7) of exhaustive exercise (4 h each day of mixed aerobic and anaerobic activities in thermoneutral conditions). Blood was sampled on day 0 and day 7 at baseline (0700 hours), and before and immediately after cold exposure. RESULTS: At 0700 hours, ACTH and cortisol were elevated (p < 0.05) after 7 d of exercise, compared with control conditions. Following exercise-cold exposure, cortisol, T3, and T4 increased (p < 0.05) similarly on both day 0 and day 7. ACTH and TSH did not increase as a result of exercise-cold exposure on either day. CONCLUSIONS: These data indicate that 7 d of exercise elevates basal (0700 hours) pituitary-adrenal stress hormones (ACTH, cortisol). However, 7 d of exercise did not modify adrenal or thyroid hormone responses, relative to the day 0 cold exposure, suggesting that they are not responsible for the blunted vasoconstriction during exercise-cold exposure following 7 consecutive days of exercise.

Adrenocorticotropic Hormone↗

PubMed2002

Pre-exercise oral creatine ingestion does not improve prolonged intermittent sprint exercise in humans.

BACKGROUND: This investigation determined whether pre-exercise oral Cr ingestion could enhance prolonged intermittent sprint exercise performance. METHODS EXPERIMENTAL DESIGN: a randomised, double-blind crossover design was employed. SETTING: testing was performed at the Western Australian Institute of Sport and participants were monitored and treated by both scientific and medical personnel. PARTICIPANTS: eight active, but not well-trained males with a background in multiple-sprint based sports acted as subjects for this investigation. INTERVENTIONS: subjects ingested either 15 g Cr.H2O or placebo 120 min and 60 min prior to the start of an 80-min maximal sprint cycling task (10 sets of multiple 6-sec sprints with varying active recoveries). Subjects were retested 14 days later, being required to ingest the alternate supplement and repeat the exercise test. MEASURES: performance variables (work done and peak power) were obtained throughout the exercise challenge. Muscle biopsies (vastus lateralis) were raised to a peak of 2348+/-223 micromol x l(-1) prior to the commencement of exercise after Cr ingestion. There were no significant changes in any cycling performance parameters following Cr ingestion, although blood La- was significantly lower (p<0.05) than placebo at all time points during were taken preexercise as well as immediately and 3 min post-exercise in order to determine concentrations of ATP, PCr, Cr, La- and glycogen. Venous blood was drawn prior to and on four occasions during the exercise test, and analysed for Cr, NH3+, La- and pH. RESULTS: Serum Cr concentrations exercise, and plasma NH3+ accumulation was also significantly reduced (p<0.05) in the Cr condition, but only in the second half of the 80-min exercise test. Muscle ATP and TCr levels as well as postexercise PCr replenishment were unaffected following Cr administration. CONCLUSIONS: The data suggest that although the pre-exercise ingestion of a large Cr dose was shown to have some impact on blood borne metabolites, it does not improve maximal prolonged intermittent sprint exercise performance, possibly due to an insufficient time allowed for uptake of serum Cr by skeletal muscle to occur. Therefore, this form of loading does not provide an alternative method of Cr supplementation to the traditional five-day supplementation regimes established by previous research.

Adult↗