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Effect Of Work To Rest Cycles On Cardiovascular Drift And Maximal Oxygen Uptake During Heat Stress
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Book Synopsis Effect of Work-To-Rest Cycles on Cardiovascular Drift and Maximal Oxygen Uptake During Heat Stress by : Anne Mulholland
Download or read book Effect of Work-To-Rest Cycles on Cardiovascular Drift and Maximal Oxygen Uptake During Heat Stress written by Anne Mulholland and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cardiovascular (CV) strain, indexed as CV drift-a progressive increase in heart rate (HR) and decrease in stroke volume (SV) during prolonged exercise-is exacerbated by environmental heat stress and is accompanied by a decrease in maximal work capacity (V? O 2max ). To attenuate CV strain, work:rest ratios have been recommended by the National Institute for Occupational Safety and Health (NIOSH). Whether these guidelines sufficiently mitigate CV drift and preserve V? O 2max is unknown. PURPOSE: To test the hypothesis that during moderate work (201-300 kcal/h) in hot conditions [indoor wet-bulb globe temperature (WBGTin )=29 ℗ʻC] utilizing the recommended 45:15 work:rest ratio, CV drift will 0́8accumulate' over time, and the magnitude of accumulated CV drift will be proportional to decrements in V? O 2max after 120 min. METHODS: Eight subjects [5 women; (mean℗łSD) age=25℗ł5 y; body mass=74.8℗ł11.6 kg; V? O 2max =42.9℗ł5.6 mL/kg/min] completed 3 sessions on different days. The first visit involved measurement of V? O 2max (WBGTin =18.1℗ł1.2 ℗ʻC). The following 2 experimental trials were counterbalanced (WBGTin =29.0℗ł0.6 ℗ʻC). Moderate work was achieved by 2.5 min of arm curls (4.5 kg at 20/min) and 20 min of walking (V? O 2 =1.00́31.1 L/min) on a treadmill, repeated once for a total of 45 min of work, and then followed by 15 min of seated rest. HR and SV were measured at 15 and 45 min of each work bout to evaluate CV drift. The 120-min trial consisted of 2 full work-rest cycles followed by measurement of V? O 2max ; the 15-min trial replicated the first 15 min of the 120-min visit followed by measurement of V? O 2max and was necessary to measure V? O 2max before CV drift occurred. RESULTS: CV drift accumulated between 15 and 105 min: HR increased 16.7% (18℗ł9 bpm, P=0.004) and SV decreased 16.9% (-12.3℗ł5.9 mL, P=0.003), but iii V? O 2max was not affected after 2 full work-rest cycles (P=0.14). Core body temperature increased by 0.5℗ł0.2 ℗ʻC (P=0.006) over 2 h. CONCLUSION: Although CV drift occurred after two 45:15 work:rest cycles, V? O 2max was unaffected. Work capacity is preserved during 2 hours of work in the heat with rest cycles patterned like those in this study, but CV and thermal strain persist unabated
Book Synopsis Cardiovascular Drift and Maximal Oxygen Uptake During Heat Stress in Women by : Tori Stone
Download or read book Cardiovascular Drift and Maximal Oxygen Uptake During Heat Stress in Women written by Tori Stone and published by . This book was released on 2019 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: During prolonged constant-rate exercise, heart rate and stroke volume progressively increase and decrease, respectively, characterizing cardiovascular (CV) drift. CV drift is greater when driven by hyperthermia and generally results in proportional decreases in maximal oxygen uptake (♭́2O2max). Less is known about CV drift and decrements in ♭́2O2max in women because nearly all studies on this topic focused on men. This dissertation determined the effects of hormonal status, fitness level, and sudomotor function on CV drift and ♭́2O2max in women. In 3 separate studies, CV drift was measured during 45 min of cycling in 35 ℗ʻC, immediately followed by measurement of ♭́2O2max. ♭́2O2max also was measured after 15 min in a separate trial to assess changes in ♭́2O2max over the same time interval that CV drift occurred. Study 1 compared follicular (FP) and luteal phases (LP) of the menstrual cycle during exercise at 60% ♭́2O2max. Resting and exercise core temperatures (Tre) were higher in LP, but increases during exercise (Î4Tre) were similar to FP, so the CV drift/♭́2O2max relationship was not modulated by phase. Study 2 compared high-fit (HI) and low-fit (LO) women during exercise at 60% ♭́2O2max (REL) and 500 W of metabolic heat production (FIXED). During REL, heat production and Î4Tre were significantly greater in HI versus LO, as were magnitudes of CV drift and decrements in ♭́2O2max. During FIXED, heat production, Î4Tre, CV drift, and ♭́2O2max were similar between groups. Study 3 compared women to men during exercise at 500 W of metabolic heat production. For women, sweating plateaued and accelerated Î4Tre compared to men, but differences in CV drift and ♭́2O2max were not statistically discernible between sexes. In conclusion, the relationship between CV drift and ♭́2O2max during heat stress does not change across the menstrual cycle and is not affected by fitness level, independent of metabolic heat production. The relationship is similar between men and women during 45 min of exercise at the same, relatively high load.
Book Synopsis Precooling and Exercise Capacity During Heat Stress by : Charles P. Katica
Download or read book Precooling and Exercise Capacity During Heat Stress written by Charles P. Katica and published by . This book was released on 2013 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vigorous exercise in a hot and humid environment can substantially impair exercise performance and exercise capacity compared to moderate temperature conditions. Cycling requires high force generation and consequently utilizes a high rate of energy expenditure and often takes place during the hot summer months, which also contributes to heat storage and a rise in core temperature during exercise. There are several factors that could affect exercise performance, however, one explanation for the decrease in exercise performance while working in the heat is the strain put on the cardiovascular system. Part of this strain involves cardiovascular drift (CV drift), defined as a steady increase in heart rate (HR) and a decrease in stroke volume (SV) that occur during an extended bout of constant-rate, submaximal exercise [50-75% of maximal oxygen uptake (VO2max)]. Precooling has been shown in previous studies to diminish cardiovascular strain and thus, improve exercise performance during prolonged exercise lasting between 15 - 45 min in hot ambient temperatures. In order to evaluate the effects of precooling on cycling performance, two studies and a literature review were conducted. The first study evaluated the effects of 20 min of precooling the upper body (torso, head and neck) during an active warm-up, followed by a 15-km simulated time trial. The second study evaluated the effects on CV drift following 20 min of whole body (calve, thigh, torso, neck and head) precooling. Healthy and physically active male cyclists were recruited for both of the studies. A repeated measures, counterbalanced design was used for both of the studies. For both studies, the effect of pre-cooling on time trial performance and CV drift showed very limited differences between the cooling intervention and the control trials. The method of cooling used in both trials may not be the best way to truly decrease the core temperature enough to elicit a true ergogenic effect in time trial pace cycling and CV drift. More research looking at a practical and convenient way of cooling cyclists before exercising in the heat is warranted.
Book Synopsis The Effect of Ambient Temperature on Cardiovascular Drift During Prolonged Exercise by : David LLoyd Biles
Download or read book The Effect of Ambient Temperature on Cardiovascular Drift During Prolonged Exercise written by David LLoyd Biles and published by . This book was released on 1981 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Physical Fitness/sports Medicine by :
Download or read book Physical Fitness/sports Medicine written by and published by . This book was released on 1988 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1984 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Human Circulation by : Loring B. Rowell
Download or read book Human Circulation written by Loring B. Rowell and published by Oxford University Press, USA. This book was released on 1986 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here is the first single-volume work to analyze in a comprehensive manner the mechanisms by which the human cardiovascular system adjusts to physical stresses such as exercise, heat, upright posture, and hypoxia. Emphasizing the regulation of regional blood flow and blood volume, the work delineates the unique character of the human cardiovascular system and the regulatory problems it faces. It represents a timely response to the growing interest in cardiovascular health, exercise, and physical conditioning. In describing the basic mechanisms of vasomotor control, the author focuses on the interaction between the arterial and venous systems. He indicates how control of regional circulations interacts with control of venous volume and cardiac performance, showing how vasomotor and venomotor regulation serves the entire organism. This treatment redresses an imbalance in contemporary teaching of cardiovascular physiology which has focused more on the heart than on the vasculature. The book utilizes graphics imaginatively throughout to clarify concepts in a fresh and effective way. Features: * Analytical, quantitative, and problem oriented * Uniquely comprehensive; coverage extends from small blood vessel functioning to the entire system * Imaginatively illustrated, with exceptionally clear graphics that explain basic principles and controversial ideas * Original, new ideas on how peripheral circulation influences heart performance * Probes the upper limits of human cardiovascular function, their causes and how they change
Book Synopsis Sports & Exercise Nutrition by : William D. McArdle
Download or read book Sports & Exercise Nutrition written by William D. McArdle and published by Lippincott Williams & Wilkins. This book was released on 1999 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt: ere's the first research-based text that integrates key topics in the field of exercise and sports nutrition. It is organized to clearly present information about nutrient digestion, absorption and assimilation presented first, followed by discussions on how nutrients provide energy for the body. Lecturers - Click here to order a FREE Review Copy of this title !
Book Synopsis The Effects of Ambient Heat During Exercise on Recovery Oxygen Consumption Kinetics and Resting Metabolic Rate by : Marianne Gimble
Download or read book The Effects of Ambient Heat During Exercise on Recovery Oxygen Consumption Kinetics and Resting Metabolic Rate written by Marianne Gimble and published by . This book was released on 1986 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1984 with total page 1096 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Heat Stress in Sport and Exercise by : Julien D. Périard
Download or read book Heat Stress in Sport and Exercise written by Julien D. Périard and published by Springer. This book was released on 2019-03-06 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is designed to provide a flowing description of the physiology of heat stress, the illnesses associated with heat exposure, recommendations on optimising health and performance, and an examination of Olympic sports played in potentially hot environmental conditions. In the first section the book examines how heat stress effects performance by outlining the basics of thermoregulation and how these responses impact on cardiovascular, central nervous system, and skeletal muscle function. It also outlines the pathophysiology and treatment of exertional heat illness, as well as the role of hydration status during exercise in the heat. Thereafter, countermeasures (e.g. cooling and heat acclimation) are covered and an explanation as to how they may aid in decreasing the incidence of heat illness and minimise the impairment in performance is provided. A novel and particular feature of the book is its inclusion of sport-specific chapters in which the influence of heat stress on performance and health is described, as well as strategies and policies adopted by the governing bodies in trying to offset the deleterious role of thermal strain. Given the breadth and scope of the sections, the book will be a reference guide for clinicians, practitioners, coaches, athletes, researchers, and students.
Book Synopsis Physiological Responses to Changes in Exercise by : Anton J. Volovsek
Download or read book Physiological Responses to Changes in Exercise written by Anton J. Volovsek and published by . This book was released on 1990 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerospace Medicine and Biology written by and published by . This book was released on 1983 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into NASA scientific and technical information system and announced in Scientific and Technical Aerospace Reports (STAR), International Aerospace Abstracts (IAA).
Book Synopsis The Effects of Constant-load Exercise at Percentages of the Ventilation Thresholds on the Magnitude of Heart Rate Drift by : Raymond Martinez
Download or read book The Effects of Constant-load Exercise at Percentages of the Ventilation Thresholds on the Magnitude of Heart Rate Drift written by Raymond Martinez and published by . This book was released on 2012 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to determine the effects of constant-load exercise performed above and below TH1 on the magnitude of HR drift, a component of CV drift. Data was collected from 9 trained cyclists who have been cycling 3-5 hours per week for greater than 1 year. Subjects reported to the laboratory on three occasions. The first visit consisted of a maximal exercise test and two power detection rides. These were conducted to determine the workloads for the remaining two visits. Visits 2 and 3 consisted of rides to fatigue at an exercise intensity that elicited a VO2 that was 5% below TH1 and at the midpoint of TH1 and TH2 (midTH). Fatigue was determined when subjects could no longer maintain a cadence within 5 rpms of their self-selected cadence. Heart rate was recorded every minute; VO2 was collected continuously for the first 5 minutes then every 10 minutes for 2 minutes. Blood pressure and RPE were recorded every 10 minutes. Results Subjects displayed a significant main effect for intensity. Average HR during the -5%TH was 159±13 bpm and was significantly lower than the midTH trial with a HR of 167±15 bpm (p=.002). There was also a significant main effect of duration (p=.000). Tukey's post hoc analysis revealed a significant HR rise from 156±14 bpm at 20% TTF to 161±14 bpm at 40% TTF (p=.000). Heart rate rose again from 40% TTF to 165±15 bpm at 60% TTF (p=.002). Heart rate did not rise again until 100% TTF (170±15bpm p=.04) (see Figure 2) . The drift in HR represents a 9.1% change in HR in the -5%TH and an 8.9% in the midTH trial. Despite the statistical significance for both intensity and time, there was not a statistically significance interaction effect (p=0.645). HR was significantly different for intensity and time but there was not statistical significance for the interaction of intensity vs. time. The magnitude of HR drift above and below TH1 was nearly the same percent change. Prior CV drift studies utilizing percentage of maximal oxygen consumption as the prescription of exercise yielded similar magnitude of drift. Future CV drift studies can design methods like traditional studies.
Book Synopsis Influence of Heat Stress and Acclimation on Maximal Aerobic Power by : Michael N. Sawka
Download or read book Influence of Heat Stress and Acclimation on Maximal Aerobic Power written by Michael N. Sawka and published by . This book was released on 1984 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thirteen male volunteers performed cycle ergometer maximal oxygen uptake (V02 max) tests in moderate (21 C, 30% rh) and hot (49 C, 20% rh) environments, before and after a nine-day heat acclimation program. This program resulted in significantly decreased (P0.01) final heart rate (24 bt/min) and rectal temperature (0.4 C) from the first to last day of acclimation. The V02 max was lower (P
Book Synopsis Oxygen Uptake Kinetics in Sport, Exercise and Medicine by : Andrew M. Jones
Download or read book Oxygen Uptake Kinetics in Sport, Exercise and Medicine written by Andrew M. Jones and published by Routledge. This book was released on 2013-07-04 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite its crucial importance, scientists interested in the limitations of human physical performance have only just started to give the field of oxygen uptake kinetics the attention it deserves. Understanding the principal determinant of the oxygen uptake kinetics is fundamental to improving human performance or the quality of life. This book provides a detailed overview of the current state of knowledge of this emerging field of study, and features: * an introduction to oxygen uptake kinetics and historical development of the discipline * measurement and analysis of oxygen uptake kinetics * control of and limitations to oxygen uptake kinetics * applications of oxygen uptake kinetics in a range of human populations. Oxygen Uptake Kinetics in Sport, Health and Medicine is richly illustrated and structured to enable easy access of information and represents an invaluable resource for students and researchers in exercise physiology, as well as for respiratory physiologists and pulmonary clinicians.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2626 pages. Available in PDF, EPUB and Kindle. Book excerpt:
