Peak treadmill running velocity during the VO2 max test predicts running performance

Twenty specialist marathon runners and 23 specialist ultra-marathon runners underwent maximal exercise testing to determine the relative value of maximum oxygen consumption (VO2max), peak treadmill running velocity, running velocity at the lactate turnpoint, VO2 at 16 km h-1, % VO2max at 16 km h-1, and running time in other races, for predicting performance in races of 10-90 km. Race time at 10 or 21.1 km was the best predictor of performance at 42.2 km in specialist marathon runners and at 42.2 and 90 km in specialist ultra-marathon runners (r = 0.91-0.97). Peak treadmill running velocity was the best laboratory-measured predictor of performance (r = -0.88(-)-0.94) at all distances in ultra-marathon specialists and at all distances except 42.2 km in marathon specialists. Other predictive variables were running velocity at the lactate turnpoint (r = -0.80(-)-0.92); % VO2max at 16 km h-1 (r = 0.76-0.90) and VO2max (r = 0.55(-)-0.86). Peak blood lactate concentrations (r = 0.68-0.71) and VO2 at 16 km h-1 (r = 0.10-0.61) were less good predictors. These data indicate: (i) that in groups of trained long distance runners, the physiological factors that determine success in races of 10-90 km are the same; thus there may not be variables that predict success uniquely in either 10 km, marathon or ultra-marathon runners, and (ii) that peak treadmill running velocity is at least as good a predictor of running performance as is the lactate turnpoint. Factors that determine the peak treadmill running velocity are not known but are not likely to be related to maximum rates of muscle oxygen utilization.     

The weighted walking test as an alternative method of assessing aerobic power

The aim of the present study was to determine maximal oxygen uptake (VO2max) directly during uphill walking exercise and to compare these values with those achieved during running and cycling exercise. Forty untrained students (20 males and 20 females) took part in three exercise tests. The running test was performed on a horizontal treadmill and the speed was gradually increased by 0.3 m . s(-1) every 3 min. The walking test was conducted on a treadmill inclined at 12% (speed of 1.8 m . s(-1)). The load was further increased every 3 min by the addition of a mass of one-twentieth of the body mass of the participant (plastic containers filled with water and added to a backpack carried by the participant). During the bicycle ergometry test, the workload was increased by 20 W every 2 min. All tests were performed until volitional exhaustion. During all tests, oxygen uptake, minute ventilation, tidal volume, respiratory frequency, heart rate, hydrogen ion concentration, base excess, and blood lactate concentration were analysed. The Pearson correlation coefficients between the weighted walking test and the commonly applied running and bicycle ergometry tests indicate a strong association with the new test in evaluating maximal oxygen uptake. The negligible differences in VO2max between the three tests for the male participants (running: 61.0 ml . kg(-1) . min(-1); walking: 60.4 ml . kg(-1) . min(-1); cycling: 60.2 ml . kg(-1) . min(-1)), and the fact that the females achieved better results on the walking test than the cycle ergometer test (running: 45.0 ml . kg(-1) . min(-1); walking: 42.6 ml . kg(-1) . min(-1); cycling: 40.1 ml . kg(-1) . min(-1)), confirm the suitability of the new method for evaluating aerobic power. The weighted walking test could be useful in the assessment of aerobic power in individuals for whom running is not advised or is difficult. In addition, the new test allows for determination of VO2max on small treadmills with a limited speed regulator, such as those found in specialist physiotherapy and fitness centres.     

Acute effects of walking on inflammatory and cardiovascular risk in sedentary post-menopausal women

Biochemical markers of inflammation are emerging as new predictors of risk of cardiovascular disease (CVD) and may alter acutely with exercise. Few studies have been conducted on the effects of walking on these markers or whether different walking intensities elicit varied effects. As there is growing interest in modifiable lifestyle factors such as walking to reduce CVD risk, these inflammatory responses warrant investigation. The aim of this study was to compare the effects of walking at 50% versus 70% of predicted maximal heart rate on C-reactive protein (CRP), plasma fibrinogen, and triglycerides in sedentary post-menopausal women. Twelve post-menopausal women (mean age 58 years, s +/-6; stature 1.62 m, s+/-0.06; body mass 66.8 kg, s +/-6.2) completed two 30-min treadmill walks in a randomized cross-over design. Fasted blood samples were taken (for the determination of plasma fibrinogen, CRP, and lipids) before, immediately after, and 1 and 24 h after exercise. Triglyceride concentrations decreased from pre-exercise to 24 h post exercise at both walking intensities (time x group interaction, P < 0.05). No significant effects were observed for plasma fibrinogen, CRP, total cholesterol, low-density or high-density lipoprotein cholesterol (time x group interaction, P > 0.05). The results of this study suggest that fasting plasma triglycerides are decreased on the morning after 30 min of brisk walking at either 50% or 70% of maximal heart rate (moderate and vigorous intensity).     

跑台上走、跑能量消耗与运动速度的相关关系研究

目的:研究走、跑模式下健康成年男子单位时间单位体重的能量消耗与运动速度的相关关系以及单位距离单位体重的能量消耗与运动速度的相关关系;探讨相同速度走、跑两种不同的运动模式下能量消耗特征;方法:19名男性大学生作为研究对象。使用跑台控制速度,采用走、跑两种运动模式,每一速度至少测试6min,以速度递增的方式进行测试,走、跑模式转换时休息至安静状态。使用VO2000测试安静以及运动中的气体代谢参数,PO-LAR表测试心率;结果:建立走模式以及跑模式下的能量消耗与速度之间的拟合方程;单位时间单位体重的能耗与走速二次曲线拟合方程的复相关系数r2=0.88;单位时间单位体重的能耗与跑速线性拟合方程的复相关系数r2=0.72;两条拟合曲线的交点坐标为(2.35m/s,141.7cal/kg/min);在测试速度范围之内,同等速度下走与跑的单位时间的能耗具有显著性差异(P<0.01),跑的能耗显著大于走的能耗。单位距离单位体重的能耗与走速的2次拟合曲线的复相关系数r2=0.98,曲线最低点的坐标为(1.14m/s,0.553cal/kg/m),单位距离单位体重的平均能耗与跑速拟合曲线的复相关系数r2=0.68;结论:1)单位时间单位体重的能耗与走速呈二次曲线关系,单位时间单位体重的能耗与跑速呈线性递增关系;2)单位距离单位体重的能耗与走速呈"U"型曲线关系;单位距离单位体重的能耗与跑速呈线性递减趋势,说明在一定速度范围内随着跑速的增加单位距离单位体重的能耗降低。     

Prediction of maximum oxygen consumption from walking, jogging, or running

The purpose of this study was to develop a submaximal, 1.5-mile endurance test for college-aged students using walking, jogging, or running exercise. College students (N = 101: 52 men, 47 women), ages 18-26years, successfully completed the 1.5-mile test twice, and a maximal graded exercise test. Participants were instructed to achieve a "somewhat hard" exercise intensity (rating of perceived exertion = 13) and maintain a steady pace throughout each 1.5-mile test. Multiple linear regression generated the following prediction equation: VO2 max = 65.404 + 7.707 x gender (1 = male; 0 =female) - 0.159 x body mass (kg) - 0.843 x elapsed exercise time (min; walking, jogging orrunning). This equation shows acceptable validity (R = .86, SEE = 3.37 ml x kg(-1) min(-1)) similar to the accuracy of comparable field tests, and reliability (ICC = .93) is also comparable to similar models. The statistical shrinkage is minimal (R(press) = 0.85, SEE(press) = 3.51 ml x kg(-) x min(-1)); hence, it should provide comparable results when applied to other similar samples. A regression model (R =.90, and SEE = 2.87 ml x kg(-1) min(-1)) including exercise heart rate was also developed: VO2 max = 100.162 +/- 7.301 x gender(1 = male; 0 =female) - 0.164 x body mass (kg) - 1.273 x elapsed exercise time -0.156 x exercise heart rate, for those who have access to electronic heart rate monitors. This submaximal 1.5-mile test accurately predicts maximal oxygen uptake (VO2max) without measuring heart rate and is similar to the 1.5-mile run in that it allowsfor mass testing and requires only a flat, measured distance and a stopwatch. Further, it can accommodate a wide range of fitness levels (from walkers to runners).     

Acute effects of walking on inflammatory and cardiovascular risk in sedentary post-menopausal women

Abstract

Biochemical markers of inflammation are emerging as new predictors of risk of cardiovascular disease (CVD) and may alter acutely with exercise. Few studies have been conducted on the effects of walking on these markers or whether different walking intensities elicit varied effects. As there is growing interest in modifiable lifestyle factors such as walking to reduce CVD risk, these inflammatory responses warrant investigation. The aim of this study was to compare the effects of walking at 50% versus 70% of predicted maximal heart rate on C-reactive protein (CRP), plasma fibrinogen, and trigylcerides in sedentary post-menopausal women. Twelve post-menopausal women (mean age 58 years, s ± 6; stature 1.62 m, s ± 0.06; body mass 66.8 kg, s ± 6.2) completed two 30-min treadmill walks in a randomized cross-over design. Fasted blood samples were taken (for the determination of plasma fibrinogen, CRP, and lipids) before, immediately after, and 1 and 24 h after exercise. Triglyceride concentrations decreased from pre-exercise to 24 h post exercise at both walking intensities (time×group interaction, P < 0.05). No significant effects were observed for plasma fibrinogen, CRP, total cholesterol, low-density or high-density lipoprotein cholesterol (time x group interaction, P > 0.05). The results of this study suggest that fasting plasma triglycerides are decreased on the morning after 30 min of brisk walking at either 50% or 70% of maximal heart rate (moderate and vigorous intensity).     

平板运动跑台和场地环境测试走、跑运动能量消耗的比较研究

目的:通过平板运动跑台和场地两种不同的测试方法,对我国成年男性走、跑过程中的气体代谢和能量消耗进行比较。方法:15名成年男性在平板运动跑台和场地完成4.8km/h、6.4 km/h、8.0 km/h三个速度的走、跑运动,使用Cortex MetaMax 3 B测定走、跑过程中的气体代谢指标变化并进行统计分析。结果:走、跑时平板运动跑台测试和场地测试之间气体指标、心率和能量消耗指标有明显差异。两种测试方法得来的数据存在线性相关。使用ICC系数和Bland-Altman法分析表明两种测试方法有非常显著的一致性和相关性。结论:相同速度下平板运动跑台走、跑和场地走、跑的能量消耗差异显著,只有直接测量场地走、跑的能量消耗才能反映日常生活中和体育健身活动中走、跑运动的真实状况。应用直线回归分析建立了平板运动跑台测试和场地测试两种方法之间的转换推导公式,根据跑台测试结果推算场地测试耗氧量和能量消耗,但由于样本量较少,该公式还需要进一步增加样本量进行验证。     

Cardiorespiratory and perceptual responses to arm crank and wheelchair exercise using various handrims in male paraplegics

The purpose of the present study was to determine the effects of 10-in [0.25-m] versus 16-in [0.41-m] wheelchair handrims on cardiorespiratory and psychophysiological exercise responses during wheelchair propulsion at selected velocities. Fifteen male paraplegics (27.0 +/- 5.5 yrs) performed three discontinuous exercise tests (ACE = arm crank ergometer; WERG = wheelchair roller ergometer) and two 1600-m performance-based track trials (TRACK) under simulated race conditions. There were no significant differences in HR, VO2, VE, HLa, or category-ratio ratings of perceived exertion (RPE) using different handrims during wheelchair propulsion at 4 km.h-1. In contrast, at 8 km.h-1 subjects demonstrated a 13% lower steady state VO2 (p less than .05) using the 10-in handrims, coincident with a 23% lower VE. Steady state HR during WERG at 8 km.h-1 using the 10-in (124.4 +/- 3.9 b.min-1) or 16-in (130.6 +/- 4.6 b.min-1) handrims were not significantly different. There were also no significant differences between ACE or WERG conditions during maximal effort for VO2 or VE. However, HRpeak during ACE was 7% higher than HRpeak during WERG16 (183 +/- 15 b.min-1 vs. 171 +/- 12 b.min-1, p less than .05), and whole blood HLa during ACE was also significantly higher (by 2.3-2.5 mmol; p less than .05) compared to WERG. There were no significant differences for HR, performance time, or RPE between trials using different handrim diameters during the 1600-m event.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of treadmill and over-ground Nordic walking

Abstract

The purpose of this study was to compare the physiological responses of Nordic walking on a specially designed treadmill and Nordic walking on a level over-ground surface. Thirteen participants completed three 1-h Nordic walking training sessions. Following the training sessions, each participant performed two 1600-m over-ground Nordic walking trials at a self-selected pace. Each participant then completed two 1600-m Nordic walking treadmill trials on a Hammer Nordic Walking XTR Treadmill®, at the mean walking speed of their two over-ground Nordic walking trials. Breath-by-breath analysis of oxygen uptake ([Vdot]O₂) and heart rate was performed during each trial. Caloric expenditure was calculated using the [Vdot]O₂. Rating of perceived exertion (RPE) was assessed at the end of each trial. We found no significant differences in physiological variables collected during the two over-ground Nordic walking trials or the two treadmill Nordic walking trials. Mean walking speed was 106.96±11.49 m · min^?1. Mean heart rate during treadmill walking (99±13 beats · min^?1) was 22% lower than that during the over-ground condition (126±17 beats · min^?1). Mean [Vdot]O₂ and mean caloric expenditure were also lower during treadmill walking (15.18±3.81 ml · min^?1 · kg^?1, 0.08±0.02 kcal · min^?1 · kg^?1) than over-ground walking (24.16±4.89 ml · min^?1 · kg^?1, 0.12±0.02 kcal · min^?1 · kg^?1). Analysis of variance demonstrated that all variables were significantly higher during over-ground Nordic walking (P<0.001). A Mann-Whitney U-test demonstrated that the RPE for over-ground Nordic walking was greater than that for treadmill Nordic walking (P=0.02). Thus over-ground Nordic walking created a greater physiological stress than treadmill Nordic walking performed at the same speed and distance. The reason for this difference may have been the relatively narrow walking and poling decks on the treadmill, which made it difficult for the participants to place their poles correctly and maintain a consistent walking pattern. This would decrease the contribution of the arm muscles to overall oxygen consumption. In conclusion, the Hammer Nordic Walking XTR Treadmill® does not replicate the physiological stress of over-ground Nordic walking. Increasing the width of the decks could eliminate the discrepancy.     

Reliability of heart rate responses at given ratings of perceived exertion in cycling and walking

Eleven healthy men (M age = 27 years, SD = 4) completed three cycling and three walking trials in an alternating order. During each trial, participants were allowed, within 3 min, to adjust the work rate to correspond to given rating of perceived exertion (RPE) values according to the following order: RPE 11, 13, and 15. For cycling as well as walking, at each RPE there were no significant differences between mean heart rate responses across the three trials (p > .05). Mode-specific estimates for heart rate intraclass correlation coefficient and coefficient of variation ranged between .80 and .91, and 5.6% and 8.3%, respectively. This study provides absolute reliability estimates for heart rate responses when using RPE in a production format and suggests there may be RPE- (and mode) specific practice requirements for achieving a reliable heart rate response at a given RPE.     

Shoe cleat position during cycling and its effect on subsequent running performance in triathletes

Abstract

Research with cyclists suggests a decreased load on the lower limbs by placing the shoe cleat more posteriorly, which may benefit subsequent running in a triathlon. This study investigated the effect of shoe cleat position during cycling on subsequent running. Following bike-run training sessions with both aft and traditional cleat positions, 13 well-trained triathletes completed a 30?min simulated draft-legal triathlon cycling leg, followed by a maximal 5?km run on two occasions, once with aft-placed and once with traditionally placed cleats. Oxygen consumption, breath frequency, heart rate, cadence and power output were measured during cycling, while heart rate, contact time, 200?m lap time and total time were measured during running. Cardiovascular measures did not differ between aft and traditional cleat placement during the cycling protocol. The 5?km run time was similar for aft and traditional cleat placement, at 1084?±?80?s and 1072?±?64?s, respectively, as was contact time during km 1 and 5, and heart rate and running speed for km 5 for the two cleat positions. Running speed during km 1 was 2.1%?±?1.8 faster (P?<?0.05) for the traditional cleat placement. There are no beneficial effects of an aft cleat position on subsequent running in a short distance triathlon.     

Maximal lactate steady state in trained adolescent runners

The aims of this study were: (1) to identify the exercise intensity that corresponds to the maximal lactate steady state in adolescent endurance-trained runners; (2) to identify any differences between the sexes; and (3) to compare the maximal lactate steady state with commonly cited fixed blood lactate reference parameters. Sixteen boys and nine girls volunteered to participate in the study. They were first tested using a stepwise incremental treadmill protocol to establish the blood lactate profile and peak oxygen uptake (VO2). Running speeds corresponding to fixed whole blood lactate concentrations of 2.0, 2.5 and 4.0 mmol x l(-1) were calculated using linear interpolation. The maximal lactate steady state was determined from four separate 20-min constant-speed treadmill runs. The maximal lactate steady state was defined as the fastest running speed, to the nearest 0.5 km x h(-1), where the change in blood lactate concentration between 10 and 20 min was < 0.5 mmol x l(-1). Although the boys had to run faster than the girls to elicit the maximal lactate steady state (15.7 vs 14.3 km x h(-1), P < 0.01), once the data were expressed relative to percent peak VO2 (85 and 85%, respectively) and percent peak heart rate (92 and 94%, respectively), there were no differences between the sexes (P > 0.05). The running speed and percent peak VO2 at the maximal lactate steady state were not different to those corresponding to the fixed blood lactate concentrations of 2.0 and 2.5 mmol x l(-1) (P > 0.05), but were both lower than those at the 4.0 mmol x l(-1) concentration (P < 0.05). In conclusion, the maximal lactate steady state corresponded to a similar relative exercise intensity as that reported in adult athletes. The running speed, percent peak VO2 and percent peak heart rate at the maximal lactate steady state are approximated by the fixed blood lactate concentration of 2.5 mmol x l(-1) measured during an incremental treadmill test in boys and girls.     

Assessment of energy expenditure in children using the RT3 accelerometer

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 (VO2) 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 R2 = 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.     

不同步频和步幅的5km跑过程中运动员心率变化的对比研究

为了观察中长跑运动员长距离跑过程中步频和步幅的变化对身体机能反应的影响,8名运动员在跑台上分别采取主动加大步幅和主动减小步幅而增快步频的跑法,以相同的速度进行了两次5km跑,记录运动员在跑步过程中心率的变化并进行对比。结果显示,在相同速度5km跑的过程中,运动员采取主动减小步幅的跑法,其心率均值显著低于采取主动加大步幅的跑法。提示,长距离跑过程中,运动员采取主动减小步幅,或加大步频的跑法较为省力。     

Unstable footwear as a speed-dependent noise-based training gear to exercise inverted pendulum motion during walking

ABSTRACT

Previous research on unstable footwear has suggested that it may induce mechanical noise during walking. The purpose of this study was to explore whether unstable footwear could be considered as a noise-based training gear to exercise body center of mass (CoM) motion during walking. Ground reaction forces were collected among 24 healthy young women walking at speeds between 3 and 6 km h^?1 with control running shoes and unstable rocker-bottom shoes. The external mechanical work, the recovery of mechanical energy of the CoM during and within the step cycles, and the phase shift between potential and kinetic energy curves of the CoM were computed. Our findings support the idea that unstable rocker-bottom footwear could serve as a speed-dependent noise-based training gear to exercise CoM motion during walking. At slow speed, it acts as a stochastic resonance or facilitator that reduces external mechanical work; whereas at brisk speed it acts as a constraint that increases external mechanical work and could mimic a downhill slope.     

Prediction of maximal lactate steady state in runners with an incremental test on the field

During a maximal incremental ergocycle test, the power output associated with Respiratory Exchange Ratio equal to 1.00 (RER = 1.00) predicts maximal lactate steady state (MLSS). We hypothesised that these results are transferable for runners on the field. Fourteen runners performed a maximal progressive test, to assess the speed associated with RER = 1.00, and several 30 minutes constant velocity tests to determine the speed at MLSS. We observed that the speeds at RER = 1.00, at the second ventilatory threshold (VT2) and at MLSS did not differ (15.7 ± 1.1 km · h?1, 16.2 ± 1.4 km · h?1, 15.5 ± 1.1 km · h?1 respectively). The speed associated with RER = 1.00 was better correlated with that at MLSS (r = 0.79; p = 0.0008) than that at VT2 (r = 0.73; p = 0.002). Neither the concentration of blood lactate nor the heart rate differed between the speed at RER = 1.00 and that at MLSS from the 10th and the 30th minute of the constant velocity test. Bland and Altman analysis showed a fair agreement between the speed at MLSS and that at RER (0.2 ± 1.4 km · h?1). This study demonstrated that the speed associated with RER = 1.00 determined during maximal progressive track running allows a fair estimation of the speed associated with MLSS, markedly decreasing the burden of numerous invasive tests required to assess it.     

Moderate-domain pulmonary oxygen uptake kinetics and endurance running performance

The aims of this study were to determine if the primary time constant (tau) for oxygen uptake (VO2) at the onset of moderate-intensity treadmill exercise is related to endurance running performance, and to establish if tau could be considered a determinant of endurance running performance. Thirty-six endurance trained male runners performed a series of laboratory tests, on separate days, to determine maximal oxygen uptake (VO2max), the ventilatory threshold (VT) and running economy. In addition, runners completed six transitions from walking (4 km x h-1) to moderate-intensity running (80% VT) for the determination of the VO2 primary time constant and mean response time. During all tests, pulmonary gas-exchange was measured breath-by-breath. Endurance running performance was determined using a treadmill 5-km time-trial, after which runners were considered as combined performers (n=36) and, using a ranking system, high performers (n=10) and low performers (n=10). Relationships between tau and endurance running performance were quantified using correlation coefficients (r). Stepwise multiple regression was used to determine the primary predictor variables of endurance running performance in combined performers. Moderate correlations were observed between tau, mean response time and endurance running performance, but only for the combined performers (r=-0.55, P=0.001 and r=-0.50, P=0.002, respectively). The regression model for predicting 5-km performance did not include tau or mean response time. The velocity at VO2max was strongly correlated to endurance running performance in all groups (r=0.72 - 0.84, P < 0.01) and contributed substantially to the prediction of performance. In conclusion, the results suggest that despite their role in determining the oxygen deficit and having a moderate relationship with endurance running performance, neither tau nor mean response time is a primary determinant of endurance running performance.     

Validation of a single-stage submaximal treadmill walking test

The single-stage treadmill walking test of Ebbeling et al. is commonly used to predict maximal oxygen consumption (.VO(2max)) from a submaximal effort between 50% and 70% of the participant's age-predicted maximum heart rate. The purpose of this study was to determine if this submaximal test correctly predicts .VO(2max) at the low (50% of maximum heart rate) and high (70% of maximum heart rate) ends of the specified heart rate range for males and females aged 18 - 55 years. Each of the 34 participants completed one low-intensity and one high-intensity trial. The two trials resulted in significantly different estimates of .VO(2max) (low-intensity trial: mean 40.5 ml . kg(-1) . min(-1), s = 9.3; high-intensity trial: 47.5 ml . kg(-1) . min(-1), s = 8.8; P < 0.01). A subset of 22 participants concluded their second trial with a .VO(2max) test (mean 47.9 ml . kg(-1) . min(-1), s = 8.9). The low-intensity trial underestimated (mean difference = -3.5 ml . kg(-1) . min(-1); 95% CI = -6.4 to -0.6 ml . kg(-1) . min(-1); P = 0.02) and the high-intensity trial overestimated (mean difference = 3.5 ml . kg(-1) . min(-1); 95% CI = 1.1 to 6.0 ml . kg(-1) . min(-1); P = 0.01) the measured .VO(2max). The predictive validity of Ebbeling and colleagues' single-stage submaximal treadmill walking test is diminished when performed at the extremes of the specified heart rate range.     

第27届奥运会女子20公里竞走王丽萍、刘宏宇关键技术解析

国际田联的“竞走定义”规范了竞走比赛的技术动作标准。如果运动员违反“竞走定义”受到3名不同裁判员的严重警告，将被取消比赛资格，因此“竞走定义”成为竞走的关键技术。在第27届奥运会上王丽萍荣获女子20公里竞走项目金牌，但仍受到2名裁判员的严重警告。世界杯赛和世界锦标赛的双赛冠军刘洪宇，在第27届奥运会女子20公里比赛中于16公里处，因受到3名不同裁判员的严重警告，被取消比赛资格，失去争夺金牌的机会。因此，对王丽萍、刘宏宇竞走关键技术的解析是必要的，对符合“竞走定义”的技术给予巩固，对违反“竞走定义”的技术给予改进。     

Match analysis and heart rate of futsal players during competition

Heart rates were monitored and time-motion analysis performed for 10 players (mean age 25.6 years, s = 2.5; body mass 73.8 kg, s = 5.7 kg; height 1.75 m, s = 0.06) during four competitive futsal matches. Mean heart rate during the match was 90% (s = 2) of maximum heart rate. Heart rate records were classified based on the percentage of time spent in three zones (>85%, 85-65%, and <65% maximum heart rate); players spent 83%, 16%, and 0.3% in these three zones, respectively. During the second period, there was a significant reduction (P < 0.01) in the percentage of time spent at an intensity above 85% of maximum heart rate (first vs. second period: 86% vs. 79%). Players' movements were classified as standing, walking, jogging, medium-intensity running, high-intensity running, and sprinting (maximal speed running). Time-motion analysis indicated that the mean distance covered per minute of play was 117.3 m (s = 11.6), of which 28.5% (s = 2.2) was covered while performing medium-intensity running, 13.7% (s = 2) during high-intensity running, and 8.9% (s=3.4) while sprinting. From the results, we conclude that futsal is a multiple-sprints sport in which there are more high-intensity phases than in soccer and other intermittent sports.