1,721,157 research outputs found
Last Word on Viewpoint: Perception of effort during exercise is independent of afferent feedback from skeletal muscles, heart, and lungs
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Perception of effort during exercise is independent of afferent feedback from skeletal muscles, heart, and lungs
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Is peripheral locomotor muscle fatigue during endurance exercise a variable carefully regulated by a negative feedback system?
No full textPsychobiology of fatigue during endurance exercise
No full textTraditionally it has been assumed that highly motivated people terminate endurance exercise because of muscle fatigue or, more recently, because of the subconscious action of a central governor that forces humans to stop before exercise can cause serious bodily damage. This chapter described an alternative psychobiological model that integrates exercise physiology with motivation psychology and cognitive neuroscience to provide a single and testable theoretical explanation for the effects of both physiological and psychological manipulations on endurance performance. This psychobiological model also provides a novel explanation as to why perception of effort increases over time and how this fatigue interacts with motivational factors to determine for how long an individual can sustain endurance exercise
A pilot study to assess the feasibility of a submaximal exercise test to measure individual response to cardiac medication in dogs with acquired heart failure
No full textExercise testing is not commonly used in canine medicine because of several limitations. The aim of this study was to investigate the suitability of a treadmill test to measure the exercise capacity of untrained canine cardiac patients and to measure some biological parameters that might reflect the tolerance of dogs with heart failure to submaximal exercise. The exercise capacity of seven dogs with naturally occurring heart failure was evaluated before the institution of cardiac medication and 7 days after the beginning of the study. An additional re-examination was requested after 28 days. The exercise test was performed on a motorized treadmill at three different speeds (0.5 m/s, 1.0 m/s and 1.5 m/s). The following parameters were measured at the end of each stage and after 20 min recovery: heart rate, rectal temperature, glucose, lactate, aspartate aminotransferase, creatine kinase, PVO2 PVCO2pH, haematocrit, bicarbonate, sodium, potassium and chloride. Serum cardiac troponin-I was also measured at the beginning of the test and at the end of the recovery period. Owners' perception reflected the ability of their dogs to exercise on the treadmill. Lactate level increased noticeably with the intensity of the exercise test, and its variation coincided with different exercise tolerance observed by the owners. Heart rate seemed to follow a similar trend in the few dogs presented in sinus rhythm. None of the remaining parameters appeared to be sensitive indicators of activity level in the dogs used in this study. The treadmill exercise test in dogs with acquired heart failure is feasible and might provide useful information for assessing individual response to cardiac medication. Lactate and heart rate seemed to reflect individual levels of exercise tolerance, although further studies are necessary to confirm the reliability and repeatability of this test. © Springer Science+Business Media, Inc. 2007
AN INTRODUCTION TO ENDURANCE PERFORMANCE IN SPORT: PSYCHOLOGICAL THEORY AND INTERVENTIONS
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Reliability of an incremental exercise test to evaluate acute blood lactate, heart rate and body temperature responses in Labrador retrievers
No full textThirteen healthy Labrador retrievers underwent a 5-stage incremental treadmill exercise test to assess its reliability. Blood lactate (BL), heart rate (HR), and body temperature (BT) were measured at rest, after each stage of exercise, and after a 20-min recovery. Reproducibility was assessed by repeating the test after 7 days. Two-way MANOVAs revealed significant differences between consecutive stages, and between values at rest and after recovery. There was also a significant reduction in physiological strain between the first and second trial (learning effect). Test reliability expressed as typical error (BL = 0.22 mmol/l, HR = 9.81 bpm, BT = 0.22°C), coefficient of variation (BL = 19.3%, HR = 7.9% and BT = 0.6%) and test-retest correlation (BL = 0.89, HR = 0.96, BT = 0.95) was good. Results support test reproducibility although the learning effect needs to be controlled when investigating the exercise-related problems commonly observed in this breed. © Springer-Verlag 2009
The effect of knee angle on the external validity of isometric measures of lower body neuromuscular function
No full textThe aim of this study was to evaluate the effect of varying knee angle (120° and 90°) on the external validity of an isometric leg press test with reference to vertical jump performance. Isometric peak force (PF120 and PF90), rate of force development (RFD120 and RFD90), and maximum height reached with a squat jump and countermovement jump were measured in 14 males. Although RFD120 was significantly correlated with squat jump and counter-movement jump performance (r = 0.71 and 0.69), and the correlations with PF120 approached statistical significance (r = 0.53 and 0.50), neither PF90 nor RFD90 was significantly related to vertical jump performance. Furthermore, although both RFD120 and PF120 were significantly different between the best five and the worst five jumpers, RFD90 and PF90 did not differentiate between individuals’ vertical jump performance. We conclude that the choice of joint angle affects the external validity of isometric strength testing. Based on our results, we recommend accurate control of biomechanical specificity and assessment at different angles to find the position at which isometric strength testing is most comfortable. © 2000 Taylor & Francis Ltd
Counterpoint: Afferent feedback from fatigued locomotor muscles is not an important determinant of endurance exercise performance.
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Can Doping be a Good Thing? Using Psychoactive Drugs to Facilitate Physical Activity Behaviour
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