Treadmill Exercise Test (treadmill + exercise_test)

Distribution by Scientific Domains


Selected Abstracts


Thyroid hormone responses to endurance exercise

EQUINE VETERINARY JOURNAL, Issue S36 2006
E. A. GRAVES
Summary Reasons for performing study: Limited information exists about changes in circulating thyroid hormone concentrations during prolonged endurance exercise in horses. Objective: To examine the effects of prolonged exercise on serum iodothyronine concentrations in horses performing endurance exercise of varying distances. Methods: Serum concentrations of iodothyronines were measured in horses before and after completion of 40, 56, 80 and 160 km endurance rides (Study 1); daily during a 5 day, 424 km endurance ride (Study 2); and before and for 72 h after completion of a treadmill exercise test simulating a 60 km endurance ride (Study 3). Results: In Study 1, 40 and 56 km of endurance exercise had little effect on serum iodothyronine concentrations with the exception of a 10% decrease (P<0.05) in free thyroxine (FT4) concentration after the 56 km ride. In contrast, total thyroxine (T4), total triiodothyronine (T3), FT4 and free triiodothyronine (FT3) concentrations all decreased (P<0.05) after successful completion of 80 and 160 km rides, with decreases ranging from 13,31% and 47,54% for distances of 80 and 160 km, respectively. Further, pre-ride T4 concentration was lower (P<0.05) and FT3 concentration was higher (P<0.05) in horses competing 160 km as compared to horses competing over shorter distances. In Study 2, serum concentrations of T4, T3 and reverse triiodothyronine (rT3) progressively decreased (P<0.05) over the course of the multi-day ride. In Study 3, the greatest decrease (P<0.05) in all iodothyronines was observed at 12 h of recovery, ranging from 25% for FT4 to 53% for FT3, but all thyroid hormone concentrations had returned to the pre-exercise values by 24 h of recovery. Conclusion: Endurance exercise results in transient decreases in serum iodothyronine concentrations. Potential relevance: These data are important to consider when thyroid gland function is assessed by measurement of serum iodothyronine concentrations in endurance horses. [source]


Effects of glucose polymer with and without potassium and different diets on glycogen repletion after a treadmill exercise test in endurance horses

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 11-12 2005
T. M. Hess
Glycogen repletion involves absorption of glucose and its uptake into the muscle cells through GLUT-4 transporters. In the muscle and adipose tissue GLUT,4 transporters facilitates the glucose transport in the presence of insulin and K+. Potassium supply has been shown to stimulate insulin secretion. This study tested the effects of a glucose polymer added with electrolytes containing potassium (GP+K) compared to a glucose polymer with electrolytes without potassium (GP-K) on glycogen repletion. Also it compared the effect of different diet adaptations on glycogen repletion. Six horses were fed a diet rich in sugar and starch (SS), and six horses a diet rich in fat and fibre (FF) for 6 months before the test. In a crossover designed study, 12 trained Arabian or Arabian cross horses were submitted to a glycogen depleting exercise test on the treadmill. After exercise stopped six horses were supplied with GP-K and six other horses supplied with GP+K, at a dose of 5 g/kg BW, and a rate of 1 g/kg BW/hour through naso-gastric gavage. Muscle biopsies were taken before, just after they stopped exercise, and 16 h after they had been supplied with glycogen replacing formulas, and analysed for muscle glycogen. Blood was taken before, after 3 h of exercise, after the stepwise exercise test, at 0, 1 and 4 h after exercise stopped and analysed for plasma glucose, insulin and [K+]. Muscle glycogen decreased from 516.41 ± 12.92 glucosyl units/kg dry weight muscle to 408.74 ± 12.92 glucosyl units/kg dry weight muscle (79%). Sixteen hours after the repletion protocol horses recovered their muscle glycogen to 458.53 ± 12.91 glucosyl units/kg dry weight muscle (89%). Plasma glucose had a glucose polymer by sampling effect (p = 0.013) and a feed by sampling effect (p = 0.022). Plasma glucose was higher in SS fed horses at 1 and 4 h after exercise. Plasma glucose was lower in GP+K supplied horses 4 h after exercise. Plasma insulin had a trend (p = 0.070) for a glucose polymer effect. No differences were found in muscle glycogen between the two GP treatments. Although the present results demonstrate that intensive nasogastric supplementation with glucose polymer can result in glycogen repletion approaching that following i.v. administration, the addition of potassium conferred no advantage. [source]


Exercise Does Not Increase QTcmax and QTcd in Diabetic Patients with Autonomic Neuropathy

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2007
MEHMET YAZICI M.D.
Background:The purpose of this study was to examine the effects of exercise on maximum QTc interval (QTcmax) and QTc dispersion (QTcd) in diabetic patients without clinically evident heart disease. Methods: Seventy-six diabetic patients who had no coronary artery disease or hypertension (group I; mean age 48 ± 9 years old) and 40 healthy volunteers (group II; mean age 46 ± 13 years old) were enrolled in the study. Cases with clinically evident heart disease were excluded from the study. Resting 12-lead electrocardiogram (ECG) and maximal treadmill exercise test (according to Bruce protocol) were performed in all cases. The QTcmax interval was determined at rest (RQTcmax) and during peak exercise (PQTcmax). Also, the QTcd was measured at rest (RQTcd) and during peak exercise (PQTcd). Autonomic neuropathy was assessed by measuring the heart rate variability (HRV). Results: There was no significant difference between clinical characteristics of two groups. In group I, HRV parameters were significantly lower than group II. RQTcd, PQTcd, RQTcmax, and PQTcmax were significantly longer in group I (56 ± 16 vs 34 ± 11; P< 0.001, 62 ± 22 vs 40 ± 15; P < 0.001, respectively). In diabetic patients, there was no significant difference between RQTcmax and PQTcmax (428 ± 19 vs 420 ± 31; P > 0.05), and no significant difference was present between RQTcd and PQTcd (56 ± 16 vs 62 ± 22; P > 0.05, respectively). Conclusion: Exercise does not affect QTcd in patients with diabetes mellitus and without clinically evident heart disease. [source]


Impairment of Coronary Microvascular Function in Patients with Neurally Mediated Syncope

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2p1 2003
JAW-WEN CHEN
CHEN, J.-W., et al.: Impairment of Coronary Microvascular Function in Patients with Neurally Mediated Syncope.Recent evidence suggests that myocardial ischemia may occur in patients with neurally mediated syncope and normal coronary angiograms. This study was conducted to evaluate if coronary microvascular function is impaired in such patients. Coronary hemodynamic studies and head-up tilt table tests (HUTs) were performed on 30 consecutive patients with normal coronary angiograms and recurrent syncope. Another ten subjects with atypical chest pain and no evidence of myocardial ischemia or syncope served as a control. Great cardiac vein flow (GCVF) and coronary sinus flow (CSF) were measured by the thermodilution method at baseline and after dipyridamole infusion (0.56 mg/kg IV for 4 minutes). Coronary flow reserve (CFR), derived from CSF and GCVF, was significantly lower in the 15 patients with positive HUT than in the other 15 patients with negative HUT (1.75 ± 0.48vs2.64 ± 0.8, P < 0.01and2.29 ± 0.45vs3.07 ± 0.63, P < 0.01, respectively). Ischemic-like ECG was noted during treadmill exercise test in 40% of the former and in 7% of the latter group(P = 0.01). There was no significant difference in CFR between patients with negative HUT and control subjects. Coronary microvascular function was impaired in syncopal patients with positive HUT and relatively preserved in those with negative HUT, suggesting the possible linkage between coronary microvascular dysfunction and the development of neurally mediated syncope. (PACE 2003; 26[Pt. I]:605,612) [source]


Influence of the Maximum Heart Rate Attained during Exercise Testing on Subsequent Heart Rate Recovery

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2010
Sina Zaim M.D.
Background: Abnormal heart rate recovery (HRR) following exercise testing has been shown to be a predictor for adverse cardiovascular events. The actual maximum heart rate (MHR) attained during the exercise test does not however have a distinct significance in traditional HRR assessment. The objective of this study was to investigate the role of MHR in HRR. Methods: This prospective study consisted of 164 patients (62% male, mean age 53.7 ± 11.7 years) who were referred for a symptom-limited standard Bruce Protocol treadmill exercise test, based on clinical indications. The patients were seated immediately at test completion and the heart rate (HR) recorded at one and two minutes postexercise. A normal HRR was defined as a HR drop of 18 beats per minute or more at the end of the first minute of recovery. The HRR profile of patients who reached ,85% of their maximum predicted heart rate (MPHR) during peak exercise were then compared to HRR profile of those who could not. Results: One hundred twelve patients (Group A) achieved a MHR , 85% of MPHR during peak exercise whereas 52 patients (Group B) did not. Chi-square analysis showed a higher incidence of normal HRR in Group A compared to Group B (p = 0.029). Analysis of variance with repeated measures showed that group A had a greater HRR at the first minute F1,162= 6.98, p = <0.01) but not the second minute (F1,162=1.83, p = .18) postexercise. Conclusion: There is a relation between the peak heart rate attained during exercise and the subsequent HRR. A low peak heart rate increases the likelihood of a less than normal HRR. Assessment of the entire heart-rate response seems warranted for more thorough risk-stratification. Ann Noninvasive Electrocardiol 2010;15(1):43,48 [source]


Retrospective study of predictive variables for maximal heart rate (HRmax) in horses undergoing strenuous treadmill exercise

EQUINE VETERINARY JOURNAL, Issue S36 2006
T. L. VINCENT
Summary Reasons for performing study: Heart rate is one of the most commonly measured variables in equine exercise physiology and relative exercise intensity commonly expressed as % of maximal heart rate. A number of influences affect maximal heart rate (HRmax), including age of the horse but other factors have not been described. Objectives: To determine if fitness, health status, gender, breed, athletic use, body mass, in addition to age, are predictive of HRmax in the horse. Methods: Maximal heart rate data from 328 horses which underwent treadmill exercise tests at 5 different laboratories were obtained retrospectively. Univariable linear regression analyses were performed on individual variables. Multiple linear regression analysis using a backward elimination modelling procedure was then used to relate the observed HRmax values simultaneously with different predictive variables. Variables were retained in the final regression model if they or any of their categories were significantly predictive of HRmax at P<0.05 and if there was a significant collective contribution to the model from inclusion of each variable, also at P<0.05. Results: Age, fitness status, laboratory, gender and breed/use (combined category) were all statistically significantly predictive of HRmax. Together these variables accounted for 41% of the variance in HRmax. Age alone accounted for only ,13% of the variation between horses in HRmax. Neither body mass nor health status were significantly predictive. Conclusions: HRmax in the horse declines with age but is also influenced by other factors. As the factors investigated accounted for only 41% of the variation between horses, other unidentified variables with a strong influence on HRmax remain to be identified. Potential relevance: Factors such as fitness, age, gender, breed and use need to be considered when interpreting estimates or measurements of HRmax. [source]


Effects of warm-up on exercise capacity, platelet activation and platelet,leucocyte aggregation in patients with claudication ,

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 1 2005
S. Pasupathy
Background: The effects of exercise and warm-up were investigated in patients with claudication. Methods: This case,control crossover study involved two treadmill exercise tests, one preceded by a warm-up. Exercise continued until maximal leg pain (patients with claudication) or exhaustion (controls). Blood was taken before, and 5 and 60 min after exercise for flow cytometric analysis of platelet activation and platelet,leucocyte aggregation. Results: Both cohorts (eight patients with claudication of median age 63 years and eight healthy controls of median age 63·5 years) demonstrated improvement in exercise capacity after warm-up (13·1 per cent, P = 0·012 and 15·6 per cent, P = 0·008 respectively). Platelet activation increased after exercise in patients with claudication (fibrinogen binding: 1·11 per cent before exercise versus 2·63 per cent after exercise, P = 0·008; P-selectin: 0·68 versus 1·11 per cent, P = 0·028). Neither agonist stimulation nor warm-up altered this trend. Platelet,leucocyte (PLA) and platelet,neutrophil (PNA) aggregation were similarly increased immediately after exercise in patients with claudication (PLA: 7·6 versus 13·0 per cent, P = 0·004; PNA: 6·8 versus 10·2 per cent, P = 0·012). These remained high 60 min after exercise only in patients with claudication, but recovered to baseline levels when preceded by warm-up. Warm-up significantly desensitized PNA after stimulation with 10 µmol/l adenosine 5,-diphosphate at all time points. Conclusion: Warm-up increased the exercise capacity of patients with claudication. Exercise induced a thromboinflammatory response, with PLA and PNA persistently increased after 60 min in patients with claudication, an effect diminished after warm-up. Copyright © 2004 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]