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1.
在热环境运动时,因大量出汗,如何饮水是很关键的。在整个运动过程中,何时喝水,喝什么,喝多少,以及对饮 水的监测和饮水的注意事项是教练员应考虑的重要问题。  相似文献   

2.
Abstract

The aim of this study was to evaluate the utility of the RT3 accelerometer in young children, compare its accuracy with heart rate monitoring, and develop an equation to predict energy expenditure from RT3 output. Forty-two volunteers (mean age 12.2 years, s = 1.1) exercised at two horizontal and graded walking speeds (4 and 6 km · h?1, 0% grade and 6% grade), and one horizontal running speed (8 km · h?1, 0% grade), on a treadmill. Energy expenditure and oxygen consumption ([Vdot]O2) served as the criterion measures. Comparison of RT3 estimates (counts and energy expenditure) demonstrated significant differences at 4, 6, and 8 km · h?1 on level ground (P < 0.01), while no significant differences were noted between horizontal and graded walking at 4 and 6 km · h?1. Correlation and regression analyses indicated no advantage of vector magnitude over the vertical plane (X) alone. A strong relationship between RT3 estimates and indirect calorimetry across all speeds was obtained (r = 0.633–0.850, P < 0.01). A child-specific prediction equation (adjusted R 2 = 0.753) was derived and cross-validated that offered a valid energy expenditure estimate for walking/running activities. Despite recognized limitations, the RT3 may be a useful tool for the assessment of children's physical activity during walking and running.  相似文献   

3.
Background: Prolonged strenuous exercise has a profound effect on cardiac function. The right heart may be more susceptible to this imposition; yet, right-sided chest leads have not been utilised in this setting. Methods: Thirty highly trained athletes at the 2014 Western States 100-mile Endurance Run from Squaw Valley to Auburn, California (body mass 68?±?12?kg, age 45?±?10?years, 57?±?15?miles per week) were recruited for the study. Pre- and post-race, a right-sided 12-lead ECG was obtained and data were extracted for P, R and S waves, J point, ST segment and T wave amplitude. Data were compared using Students T-test and statistical significance set as P?Results: There was a significant increase in P wave amplitude (29%) and QTc interval (4%) pre- to post-race from standard 12-lead ECG. From the right-sided12-lead ECG, a 23% (P?=?.01) and 38% (P?=?.03) increase in J point amplitude in V1R and V2R and a 22% (P?=?.05) increase in ST segment integral in V2R and V3R were evident. T wave inversion was evident in leads V2R–V6R in 50–90% of athletes, respectively. Close examination revealed marked heterogeneity in individual ECGs. Conclusions: Completion of a 100-mile ultra-marathon resulted in significant changes in the right-sided ECG alongside more marked responses in specific individuals. P wave, ST segment and T wave changes post-race are indicative of acute exercise-induced right heart electrical adaptation.  相似文献   

4.
ABSTRACT

Moderate-intensity continuous exercise (MICE) improves fat oxidation. High-intensity intermittent exercise (HIIE) is thought to have a greater potential for fat oxidation but it might be too demanding in the long term for patients. We hypothesized that an initial bout of HIIE could maximize fat oxidation during MICE and the following passive recovery. Eighteen healthy participants performed two acute isocaloric exercise sessions at random. MICE consisted of 45-min cycling at 50% of maximal aerobic power (Pmax). COMB began with five 1-min bouts of HIIE at Pmax (interspaced with 1-min recovery periods) followed by 35-min MICE. Gas exchange allowed substrate oxidation rate assessment.

Expressed as a % of energy expenditure, fat oxidation (%) increased during in the passive recovery following COMB (Recovery: 36.0 ± 19.4 vs 23.0 ± 20.3%; ES: 0.66; p < 0.0001). An initial bout of HIIE preceding a prolonged moderate-intensity exercise may potentiate fat oxidation during the following recovery. This might be relevant for health management of overweight/obese persons.  相似文献   

5.
Abstract

Nine males cycled at 53% (s = 2) of their peak oxygen uptake ([Vdot]O2peak) for 90 min (dry bulb temperature: 25.4°C, s = 0.2; relative humidity: 61%, s = 3). One litre of flavoured water at 10 (cold), 37 (warm) or 50°C (hot) was ingested 30 – 40 min into exercise. Immediately after the 90 min of exercise, participants cycled at 95%[Vdot]O2peak to exhaustion to assess exercise capacity. Rectal and mean skin temperatures and heart rate were recorded. The gradient of rise in rectal temperature was influenced (P < 0.01) by drink temperature. Mean skin temperature was highest in the hot trial (cold trial: 34.2°C, s = 0.5; warm trial: 34.4°C, s = 0.5; hot trial: 34.7°C, s = 0.6; P < 0.01). Significant differences were observed in heart rate (cold trial: 132 beats · min?1, s = 13; warm trial: 134 beats · min?1, s = 12; hot trial: 139 beats · min?1, s = 13; P < 0.05). Exercise capacity was similar between trials (cold trial: 234 s, s = 69; warm trial: 214 s, s = 52; hot trial: 203 s, s = 53; P = 0.562). The heat load and debt induced via drinking resulted in appropriate thermoregulatory reflexes during exercise leading to an observed heat content difference of only 33 kJ instead of the predicted 167 kJ between the cold and hot trials. These results suggest that there may be a role for drink temperature in influencing thermoregulation during exercise.  相似文献   

6.
The purpose of this study was to assess the accuracy of energy expenditure (EE) estimation and step tracking abilities of six activity monitors (AMs) in relation to indirect calorimetry and hand counted steps and assess the accuracy of the AMs between high and low fit individuals in order to assess the impact of exercise intensity. Fifty participants wore the Basis watch, Fitbit Flex, Polar FT7, Jawbone, Omron pedometer, and Actigraph during a maximal graded treadmill test. Correlations, intra-class correlations, and t-tests determined accuracy and agreement between AMs and criterions. The results indicate that the Omron, Fitbit, and Actigraph were accurate for measuring steps while the Basis and Jawbone significantly underestimated steps. All AMs were significantly correlated with indirect calorimetry, however, no devices showed agreement (p < .05). When comparing low and high fit groups, correlations between AMs and indirect calorimetry improved for the low fit group, suggesting AMs may be better at measuring EE at lower intensity exercise.  相似文献   

7.
Abstract

Several studies have examined energy expenditure in various sports but there is a lack of research on the contribution of exercise and habitual activity during different training periods. This study examined changes in total daily energy expenditure (TDEE) and its components during high- and low-volume training periods. Further, changes in time spent in sedentary, light, moderate and vigorous activity in response to different training volumes were explored. Energy expenditure was measured in 15 male endurance athletes during 2 non-consecutive weeks – 1 week of high volume (>13 hours) training and another week of low volume (<7 hours) training. The SenseWear Pro 3 Armband, individual heart-rate-oxygen consumption regression and indirect calorimetry was used to measure non-exercise activity thermogensis (NEAT), exercise energy expenditure (EEE) and resting metabolic rate, respectively. Time spent at different intensities was assessed using previously established MET cutpoints. TDEE as well as EEE increased significantly with higher training volume, while no difference in NEAT occurred. Further, significantly less time was spent in sedentary activities during the high-volume week. These results suggest that highly trained athletes do not compensate for increased training volume and reduce sedentary activities to allow for more training time.  相似文献   

8.
Abstract

The purpose of this study was to examine the accuracy of the ePulse Personal Fitness Assistant, a forearm-worn device that provides measures of heart rate and estimates energy expenditure. Forty-six participants engaged in 4-minute periods of standing, 2.0 mph walking, 3.5 mph walking, 4.5 mph jogging, and 6.0 mph running. Heart rate and energy expenditure were simultaneously recorded at 60-second intervals using the ePulse, an electrocardiogram (EKG), and indirect calorimetry. The heart rates obtained from the ePulse were highly correlated (intraclass correlation coefficients [ICCs] ≥0.85) with those from the EKG during all conditions. The typical errors progressively increased with increasing exercise intensity but were <5 bpm only during rest and 2.0 mph. Energy expenditure from the ePulse was poorly correlated with indirect calorimetry (ICCs: 0.01–0.36) and the typical errors for energy expenditure ranged from 0.69–2.97 kcal · min?1, progressively increasing with exercise intensity. These data suggest that the ePulse Personal Fitness Assistant is a valid device for monitoring heart rate at rest and low-intensity exercise, but becomes less accurate as exercise intensity increases. However, it does not appear to be a valid device to estimate energy expenditure during exercise.  相似文献   

9.
The thermoregulatory responses of upper-body trained athletes were examined at rest, during prolonged arm crank exercise and recovery in cool (21.5 +/- 0.9 degrees C, 43.9 +/- 10.1% relative humidity; mean +/- s) and warm (31.5 +/- 0.6 degrees C, 48.9 +/- 8.4% relative humidity) conditions. Aural temperature increased from rest by 0.7 +/- 0.7 degrees C (P< 0.05) during exercise in cool conditions and by 1.6 +/- 0.7 degrees C during exercise in warm conditions (P< 0.05). During exercise in cool conditions, calf skin temperature decreased (1.5 +/- 1.3 degrees C), whereas an increase was observed during exercise in warm conditions (3.0 +/- 1.7 degrees C). Lower-body skin temperatures tended to increase by greater amounts than upper-body skin temperatures during exercise in warm conditions. No differences were observed in blood lactate, heart rate or respiratory exchange ratio responses between conditions. Perceived exertion at 45 min of exercise was greater than that reported at 5 min of exercise during the cool trial (P< 0.05), whereas during exercise in the warm trial the rating of perceived exertion increased from initial values by 30 min (P < 0.05). Heat storage, body mass losses and fluid consumption were greater during exercise in warm conditions (7.06 +/- 2.25 J x g(-1) x degrees C(-1), 1.3 +/- 0.5 kg and 1,038 +/- 356 ml, respectively) than in cool conditions (1.35 +/- 0.23 J x g(-1) x degrees C(-1), 0.8 +/- 0.2 kg and 530 +/- 284 ml, respectively; P < 0.05). The results of this study indicate that the increasing thermal strain with constant thermal stress in warm conditions is due to heat storage within the lower body. These results may aid in understanding thermoregulatory control mechanisms of populations with a thermoregulatory dysfunction, such as those with spinal cord injuries.  相似文献   

10.
The thermoregulatory responses of upper-body trained athletes were examined at rest, during prolonged arm crank exercise and recovery in cool (21.5 ± 0.9°C, 43.9 ± 10.1% relative humidity; mean ± s) and warm (31.5 &± 0.6°C, 48.9 - 8.4% relative humidity) conditions. Aural temperature increased from rest by 0.7 ± 0.7°C (P ? 0.05) during exercise in cool conditions and by 1.6 ± 0.7°C during exercise in warm conditions (P ? 0.05). During exercise in cool conditions, calf skin temperature decreased (1.5 ± 1.3°C), whereas an increase was observed during exercise in warm conditions (3.0 ± 1.7°C). Lower-body skin temperatures tended to increase by greater amounts than upper-body skin temperatures during exercise in warm conditions. No differences were observed in blood lactate, heart rate or respiratory exchange ratio responses between conditions. Perceived exertion at 45 min of exercise was greater than that reported at 5 min of exercise during the cool trial (P ? 0.05), whereas during exercise in the warm trial the rating of perceived exertion increased from initial values by 30 min (P ? 0.05). Heat storage, body mass losses and fluid consumption were greater during exercise in warm conditions (7.06 ± 2.25 J·g-1 ·°C-1, 1.3 ± 0.5 kg and 1038 ± 356 ml, respectively) than in cool conditions (1.35 ± 0.23 J·g-1·°C-1, 0.8 ± 0.2 kg and 530 ± 284 ml, respectively; P ? 0.05). The results of this study indicate that the increasing thermal strain with constant thermal stress in warm conditions is due to heat storage within the lower body. These results may aid in understanding thermoregulatory control mechanisms of populations with a thermoregulatory dysfunction, such as those with spinal cord injuries.  相似文献   

11.
运用交叉滞后组设计探讨学校自然环境、人际环境与青少年体育锻炼三者间的因果关联,以及性别、学段在三者中的调节效应。采用学校自然环境量表、锻炼氛围量表和体育活动等级量表,对1091名青少年进行为期12周、两阶段纵向调查。结果显示:青少年体育锻炼的性别差异显著(男性优于女性),并且学校自然环境、人际环境以及体育锻炼的学段差异也显著(初中生各指标高于高中生);学校自然环境能单向预测体育锻炼和人际环境,体育锻炼能单向预测学校人际环境,即在学校自然环境与人际环境的影响链上,青少年体育锻炼具备中介作用且该效应存在学段差异。研究表明:学校自然环境、人际环境与青少年体育锻炼存在因果关系,其中,学校自然环境能通过促进青少年体育锻炼而间接提升人际环境,且该路径对初中生影响功效更大。  相似文献   

12.
Abstract

This study was performed to determine the influence of single and repetitive exercise on nitric oxide (NO) concentration in the lung. Exhaled NO concentration (FENO) was measured during a constant-flow exhalation manoeuvre (170 ml · s?1, against a 10 cmH2O resistance) in healthy individuals (a) during and after a 100-min square-wave exercise of between 25 and 60% of maximal power output (n = 18) and (b) before and after five successive prolonged exercises (90 – 120 min, 75 – 85% of maximal heart rate) separated by 48 or 24 h (n = 8). The FENO0.170 was decreased during and after the 100-min exercise test (mean± s [xbar] : 58.5 ± 3.7% and 76.7 ± 5.2% of resting value at 90 min of exercise and 15 min post-exercise, respectively; P < 0.05). The five successive exercise sessions induced a similar post-exercise FENO0.170 decrement (73.1 ± 2.9% of resting value 15 min post-exercise), while basal FENO0.170 values were not different between the five sessions (P > 0.05). These results suggest that prolonged exercise induces a reduction in NO concentration within the lung that lasts for several minutes after the end of exercise. However, repetitive exercises (at least every 24 h) allow complete NO recovery from one session to another. The implication of such a decrease in NO availability within the lung remains to be clarified.  相似文献   

13.
Abstract

Low energy availability [(energy intake – exercise expenditure)/kg lean body mass], a component of the Female Athlete Triad, has been associated with menstrual disturbances and low bone mass. No studies have examined the energy availability of athletes across a season. The purpose of this study was to assess the prevalence of, and what contributes to, low energy availability in Division I female soccer players across a season. Nineteen participants aged 18–21 years (mean [Vdot]O2max: 57.0 ± 1.0 mL · kg?1 · min?1) were studied during the pre, mid, and post season. Mean energy availability was overall lowest at mid season, and lower at mid than post season (35.2 ± 3.7 vs. 44.5 ± 3.7 kcal · kg?1 lean body mass, P = 0.009). Low energy availability (<30 kcal · kg?1 lean body mass) was observed in 5/19 (26.3%), 5/15 (33.3%), and 2/17 (11.8%) of participants during the pre, mid, and post season. Dietary energy intake was lower mid (P = 0.008) and post season (P = 0.022) than it was pre season (pre: 2794 ± 233 kcal · day?1; mid: 2208 ± 156 kcal · day?1; post: 2161 ± 143 kcal · day?1). Exercise energy expenditure decreased significantly (P ≤ 0.001) over time (pre: 819 ± 57 kcal · day?1; mid: 642 ± 26 kcal · day?1; post: 159 ± 28 kcal · day?1). Low energy availability was due to lower dietary energy intake at lunch during pre season (P = 0.014) and during lunch and dinner during mid season (P ≤ 0.030). Energy availability was inversely related to body dissatisfaction (r = ?0.62, P = 0.017) and drive for thinness (r = ?0.55, P = 0.041) during mid season. Although most Division I female soccer players are not at risk for low energy availability, a concerning proportion exhibited low energy availability at pre or mid season. Further studies are needed to explore strategies to prevent and monitor low energy availability in these athletes.  相似文献   

14.
Abstract

The aim of this study was to assess the capability of the 3dNX? accelerometer to predict energy expenditure in two separate, free-living cohorts. Twenty-three adolescents and 14 young adults took a single dose of doubly labelled water and wore a 3dNX? activity monitor during waking hours for a 10-day period while carrying out their normal routines. Multiple linear regression with backward elimination was used to establish the strength of the associations between various indices of energy expenditure, physical activity counts, and anthropometric variables. 3dNX? output accounted for 27% and 35% of the variance in the total energy expenditure of the adolescent and young adult cohort, respectively. The explained variance increased to 78%, with a standard error of estimate of 7%, when 3dNX? output was combined with body composition variables. The 3dNX? accelerometer can be used to predict free-living daily energy expenditure with a standard error of estimate of 1.65 MJ in adolescents and 1.52 MJ in young adults. The inclusion of anthropometric variables reduces the error to approximately 1 MJ. Although it remains to cross-validate these models in other populations, early indications suggest that the 3dNX? provides a useful method of predicting energy expenditure in free-living individuals.  相似文献   

15.
This study examined the validity of the Actical accelerometer step count and energy expenditure (EE) functions in healthy young adults. Forty-three participants participated in study 1. Actical step counts were compared to actual steps taken during a 200 m walk around an indoor track at self-selected pace and during treadmill walking at different speeds (0.894, 1.56 and 2.01 m · s–1) for 5 min. The Actical was also compared to three pedometers. For study 2, 15 participants from study 1 walked on a treadmill at their predetermined self-selected pace for 15 min. Actical EE was compared to EE measured by indirect calorimetry. One-way analysis of variance and t-tests were used to examine differences. There were no statistical difference between Actical steps and actual steps in self-selected pace walking and during treadmill walking at moderate and fast speeds. During treadmill walking at slow speed, the Actical step counts significantly under predicted actual steps taken. For study 2, there was no statistical difference between measured EE and Actical-recorded EE. The Actical provides valid estimates of step counts at self-selected pace and walking at constant speeds of 1.56 and 2.01 m · s–1. The Actical underestimates EE of walking at constants speeds ≥1.38 m · s–1.  相似文献   

16.
Nine males cycled at 53% (s = 2) of their peak oxygen uptake (VO(2peak)) for 90 min (dry bulb temperature: 25.4 degrees C, s = 0.2; relative humidity: 61%, s = 3). One litre of flavoured water at 10 (cold), 37 (warm) or 50 degrees C (hot) was ingested 30 - 40 min into exercise. Immediately after the 90 min of exercise, participants cycled at 95%VO(2peak) to exhaustion to assess exercise capacity. Rectal and mean skin temperatures and heart rate were recorded. The gradient of rise in rectal temperature was influenced (P < 0.01) by drink temperature. Mean skin temperature was highest in the hot trial (cold trial: 34.2 degrees C, s = 0.5; warm trial: 34.4 degrees C, s = 0.5; hot trial: 34.7 degrees C, s = 0.6; P < 0.01). Significant differences were observed in heart rate (cold trial: 132 beats . min(-1), s = 13; warm trial: 134 beats . min(-1), s = 12; hot trial: 139 beats . min(-1), s = 13; P < 0.05). Exercise capacity was similar between trials (cold trial: 234 s, s = 69; warm trial: 214 s, s = 52; hot trial: 203 s, s = 53; P = 0.562). The heat load and debt induced via drinking resulted in appropriate thermoregulatory reflexes during exercise leading to an observed heat content difference of only 33 kJ instead of the predicted 167 kJ between the cold and hot trials. These results suggest that there may be a role for drink temperature in influencing thermoregulation during exercise.  相似文献   

17.
Epidemiological studies suggest that prolonged sitting increases all-cause mortality; yet, physiological causes underpinning prolonged sitting remain elusive. We evaluated cardiometabolic function during prolonged sitting (5 h) in 10 adults with and without 30 min of moderate exercise leading up to the sitting. Mean arterial blood pressure (MAP), heart rate (HR) and posterior tibial artery blood velocity were measured at baseline and every hour subsequently. Blood glucose was measured at baseline, 3 and 5 h, with consumption of a caloric beverage at 1 h. Seated MAP and HR values were ~17 mmHg (P < 0.001) and ~4 bpm (P < 0.05) higher for the moderate exercise versus sitting conditions. A ~ 4 cm·s?1 (16%) (P < 0.05) decline in posterior tibial artery blood velocity from prolonged sitting was observed, with no benefit conferred from moderate exercise. Postprandial glucose metabolism was not different between conditions (P > 0.05). We conclude prolonged sitting may be related to decreased posterior tibial artery blood velocity. Moreover, an acute bout of moderate exercise does not seem to attenuate cardiometabolic function during prolonged sitting in healthy, young adults.  相似文献   

18.
Abstract

Energy turnover was assessed in two conditions of mixed ultra-endurance exercise. In Study 1, energy expenditure and intake were measured in nine males in a laboratory over 24 h. In Study 2, energy expenditure was assessed in six males during an 800-km Adventure race (mean race time 152.5 h). Individual correlations between heart rate and oxygen uptake ([Vdot]O2) were established during pre-tests when kayaking, cycling, and running. During exercise, energy expenditure was estimated from continuous heart rate recordings. Heart rate and [Vdot]O2 were measured regularly during fixed cycling work rates to correct energy expenditure for drift in oxygen pulse. Mean energy expenditure was 18,050 ± 2,390 kcal (750 ± 100 kcal · h?1) and 80,000 ± 18,000 kcal (500 ± 100 kcal · h?1) in Study 1 and Study 2 respectively, which is higher than previously reported. Energy intake in Study 1 was 8,450 ± 1,160 kcal, resulting in an energy deficit of 9,590 ± 770 kcal. Body mass decreased in Study 1 (?2.3 ± 0.8 kg) but was unchanged in Study 2. Fat mass decreased in Study 2 (?2.3 ± 1.5 kg). In Study 1, muscle glycogen content decreased by only 60%. Adventure racing requires a high energy expenditure, with large inter-individual variation. A large energy deficit is caused by inadequate energy intake, possibly due to suppressed appetite and gastrointestinal problems. The oxygen pulse, comparing start to 12 h of exercise and beyond, increased by 10% and 5% in Study 1 and Study 2 respectively. Hence, estimations of energy expenditure from heart rate recordings should be corrected according to this drift.  相似文献   

19.
目的:研究低温环境下不同强度运动对糖脂代谢相关激素变化的影响,旨在为冰上项目运动者的训练监控提供一定的指导意义。方法:选取10名北京体育大学田径专项男生为研究对象,在室内温度为12℃的条件下静息、65%VO_2max和80%VO_2max强度跑台各运动20min,每次运动前后均采集血液进行相关指标的测试,每两次测试时间间隔不少于1周。结果:与静息前相比,静息20 min后血清胰岛素(Ins)水平、胰高血糖素(PG)水平、Ins/PG均有显著降低,脂联素(ADPN)水平显著升高;与65%VO_2max强度运动前相比,运动后PG水平显著降低;与80%VO2max强度运动前相比,运动后Ins水平、Ins/PG比值显著降低,PG水平显著升高。与静息后相比,65%VO_2max强度运动后血清去甲肾上腺素(NE)、PG、瘦素(LP)水平显著降低,Ins/PG、多巴胺(DA)水平显著升高,80%VO_2max强度运动后血清NE、LP水平显著降低,DA水平显著升高;与65%VO_2max强度运动后相比,80%VO2max强度运动后血清肾上腺素(Ad)、NE水平显著上升,DA、Ins、LP水平显著降低。结论:低温环境可使Ins和Ins/PG下降,ADPN升高,且以中等强度运动后血清FFA显著升高,建议在低温环境下以中等强度运动更有利于脂肪的分解。  相似文献   

20.
ABSTRACT

Despite emotional, technical and endurance implications for athletes’ performance, a consensus has yet to be reached to explain the impairment of executive functioning during exercise. In particular, recent research challenges the original assumption of a linear dose–response effect of exercise intensity on cerebral physiology and executive functioning. We propose a fatigue-based neurocognitive perspective of executive functioning during prolonged exercise, suggesting that top-down (cognitive and physical efforts) and bottom-up processes (body sensations) act in parallel of arousing mechanisms to determine cognitive outcomes. In this perspective, executive functioning during prolonged exercise would be dynamical rather than steady (i.e. positively then negatively impacted by exercise) and would be to analyse in regards of exercise termination rather than of exercise intensity.  相似文献   

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