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1.
孙泊  刘宇  李海鹏 《体育科学》2012,32(9):17-22
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。  相似文献   

2.
目的：研究4 000 m场地自行车运动VO2反应,及前15 s高功率起动对运动成绩的影响。方法：11名男子自行车运动员在功率车上进行递增负荷试验和两种不同起动强度的4 000 m运动。首先进行前60 s平均功率（128±2）%MAP即（501.7±41.9）w强度对照模式运动;5 h后进行模拟模式运动,强度在第8~10 s达到最高值235%MAP（928.3±77.6）w,后逐步下降,15 s时至平均功率（421.9±40.1）w,维持15~60 s。60 s之后两组均进行自由速度模式,强度控制在380~420 w之间。结果：整个测试过程模拟组较对照组平均功率高19 w左右,有统计学差异。模拟组15~60 sVO2高于对照组,模拟组15s~60sVO2高于对照组,而AOD却低于对照组,对整个运动表现有促进作用。结论：4 000 m场地自行车运动前15 s高输出功率可伴随着更快的VO2反应而不是单一归于节省时间理论,并可促进中等距离自行车计时运动员的摄氧动员能力。  相似文献   

3.
《体育与科学》2019,(6):101-110
目的:检查落地高度对高水平短跑运动员跳深动作下肢生物力学和反应性力量的影响并进一步确定下肢生物力学指标与反应性力量指标之间的关联性以及跳深动作的最佳负荷高度。方法:14名男子高水平短跑运动员参与四种落地高度下(0.15m、0.30m、0.45m和0.60m)的跳深动作测试。6台红外高速摄像机和2块三维测力台同步采集跳深动作的运动学和地面反作用力信号。结果:落地高度显著影响跳深动作的碰撞力和蹬伸阶段的垂直地面反作用力峰值(p=0.000和0.039),髋关节伸力矩(p=0.038)、踝关节跖屈力矩(p=0.030)和下肢支撑力矩(p=0.010),髋、膝和踝关节离心功率(p均为0.000),平均功率输出(p=0.009),反应力量指数(p=0.006)和反应力量比(p=0.029);落地高度与平均功率输出显著相关,最佳负荷高度为0.465m(R~2=0.117,p=0.037);蹬伸阶段的垂直地面反作用力峰值(r=0.816,p=0.000;r=0.927,p=0.000)和平均功率输出(r=0.961,p=0.000;r=0.770,p=0.000)与反应力量指数和反应力量比均显著相关。结论:落地高度显著影响跳深动作的下肢生物力学和反应性力量指标,蹬伸阶段垂直地面反作用力和平均功率输出与反应性力量指标均存在非常显著的相关性,在0.15m～0.60m的落地高度范围内存在实现跳深动作最大平均力学功率输出的最佳负荷高度。建议针对高水平短跑运动员跳深训练时应该根据个体运动员的最大平均功率输出、反应力量指数和反应力量比等指标确定最佳负荷高度,以实现最佳训练效果并预防运动损伤。  相似文献   

4.
目的:利用赛艇测功仪结合赛艇专项运动特点对Conconi测试进行设计和修改,以验证心率偏离点(HRDP)产生时稳定性和有效性评价Conconi测试是否可以作为评定赛艇运动员无氧阈的有效指标.方法:12名赛艇运动员在ConceptⅡ上进行递增负荷测试,每级负荷持续时间3 min,初始强度为500 m划2 min时所对应的功率,递增负荷分别为500 m划1min55 s、1 min50 s、1 min45 s、1 min40 s和1 min35 s时所对应的功率,全程佩戴心率表,并在每级负荷间歇测定血乳酸,分析HRDP和IAT产生时的功率(P)、心率(HR)、血乳酸(BLA)和时间(T),并作相关分析.结果:1)在确定HRDP和IAT各参数指标时,发现均有两名受试对象无法判定拐点,缺失判定率均为16.7%,其中心率呈线性增加1名,向右上方偏离1名;2)HRDP和IAT产生时的功率值分别为335.8±16.6、vs 321.5±9.3(W),HRDP时的功率比IAT时的功率高了4.4%,二者呈显著相关(γ=0.818,P<0.05);心率分别为176.3±10.6 vs 172.6±9.3(次/min),HRDP时的心率值比IAT时的心率值高2.1%,二者显示非常显著相关(γ=0.877,P<0.01);而乳酸值既无差异性也无相关性.结论:以赛艇运动专项特点为基础的Coneoni测试在评定赛艇运动员无氧阚功率和心率时具有一定得稳定性和有效性,Conconi测试可以作为一种检测赛艇运动员无氧阚的无创伤性测试方法.  相似文献   

5.
目的研究前列腺癌磁共振扩散张量成像(DTI)参数表观扩散系数(ADC)与各向异性分数(FA)与其病理分级(Gleason评分)的关系,评价ADC值与FA值对于前列腺癌病理分级的诊断价值及评价前列腺癌危险度分级的诊断效能。方法采用3.0 T MR对70例经病理证实的前列腺癌患者行DTI检查,b值为0和800 s/mm2。测量前列腺癌的ADC值及FA值,根据病理结果将患者按Gleason评分系统分为高、中、低危三组:Gleason≥8分、Gleason=7分、Gleason≤6分。对三组数据进行单因素方差分析(one-way ANOVA),并进行组间两两比较。采用Pearson相关分析检验前列腺癌ADC值及FA值与Gleason评分的相关性。将前列腺癌Gleason评分≤7与Gleason评分≥8两组之间进行受试者工作特性(ROC)曲线分析,判断低中危组与高危组诊断界值。结果三组前列腺癌区平均ADC值分别为(0.96±0.10)×10-3mm2/s、(0.76±0.15)×10-3mm2/s和(0.62±0.12)×10-3mm2/s,FA值分别为0.39±0.06、0.31±0.09和0.22±0.06;三组ADC值、FA值组间差异均具有统计学意义(P<0.05);ADC值、FA值与Gleason评分之间均呈负相关(ADC值r=-0.768,P<0.05;FA值r=-0.662,P<0.05),两者均随Gleason评分的增高而减小。以ADC=0.68×10-3mm2/s为临界点,区分低中危组与高危组癌灶的诊断敏感性84.2%,特异性76.9%,准确性87.1%;以FA=0.24为临界点,区分低中危组与高危组癌灶的诊断敏感性79.5%,特异性75.8%,准确性78.4%。结论前列腺癌ADC值及FA值与病理分级(Gleason评分)之间呈负相关,具有预测癌灶恶性程度的潜力,有助于预测前列腺癌的恶性程度。  相似文献   

6.
人体机械功计算方法的实验研究   总被引：1，自引：1，他引：0  
人体运动中的机械功是评定运动效果的一个重要指标,由于人体生物结构的复杂性和器官功能的多重性特点,目前还没有形成公认的分析计算方法。本研究首先在作者提出的假设之下给出四类人体机械功计算的可能方法。采用Monark864型自行车功率定负荷,JagerEOS型心肺功能测试仪测室生理能耗,用环节分析法计算机械功。14名受试都是职业自行车队队员。本研究结果提示:采用刚体力学模型计算的人体机械功可看作是运动中生理能耗的一次近似,要提高计算准确度,还需考虑其它耗能因素,建立更为精细的人体能量代谢模型。  相似文献   

7.
目的：能量消耗是周期性速度项目运动成绩的决定因素,也是教练员制定年训练量和营养方案的主要依据。旨在探究男子轮椅竞速T54级运动员不同速度下单位距离能量消耗(Cw)的特征,为推进我国轮椅竞速的科学化训练和制定合理的膳食标准提供依据和参考。方法：招募10名高水平轮椅竞速T54级运动员,年龄(22.90±5.17)岁,体重(59.27±8.31)kg,在室外田径场分别进行1次1 500 m全力运动和逐级递增负荷测试。使用便携式气体代谢仪、Polar心率带、GPSports运动表现追踪系统对受试者每次呼吸的摄氧量(VO2)、心率(HR)、速度和距离变化进行监控。通过全力运动和每级递增负荷测试的总能耗与速度的比值计算出轮椅竞速不同速度下单位距离的Cw。结果：受试者全力运动下的速度为(7.20±0.28)m/s,Cw为0.13 kJ/m;递增负荷测试的Cw从0.09 kJ/m、速度(5.38±0.25)m/s,逐渐增加到(0.12±0.02)k J/m、速度(6.45±0.29)m/s,获得Cw与速度、VO2与速度的指数回归方程,分别为Cw=0.059x...  相似文献   

8.
优秀短距离自行车运动员无氧代谢能力特征研究   总被引：13，自引：2，他引：11  
目的:比较不同性别和训练水平运动员无氧能力的差异,探讨短距离自行车运动员高能磷酸原供能、糖酵解供能和混合无氧供能能力的特征。方法:对16名优秀短距离自行车运动员进行10s(女)、15s(男)、30s和60s的无氧功测定,测定运动后即刻、运动后3min恢复心率和血乳酸。结果:1)磷酸原代谢能力表现出明显的性别差异,男运动员最大功率、相对最大功率、平均功率、相对平均功率、最大圈数都明显高于女运动员;2)30s和60s两种测试中,运动员爆发力表现出相同水平,但糖酵解代谢持续供能能力随运动时间的延长而明显下降;3)男子优秀运动员组15s无氧功最大功率、平均功率明显高于普通组。男、女最大圈数大于普通组,达到最大圈数时间小于或等于普通组;4)男子优秀组运动员30s、60s平均功率高于普通运动员组。女子优秀运动员组30s、60s平均功率、最大圈数明显高于普通运动员组,60s最大功率明显高于普通运动员组(P<0.05)。结论:1)优秀短距离自行车运动员具有较强的磷酸原代谢能力,男运动员明显强于女运动员;2)较强的糖酵解代谢能力是短距离自行车运动员无氧代谢能力的特征;3)评定磷酸原系统能力时,男、女运动员都使用10s无氧功测试为好;4)不同水平运动员的无氧代谢能力表现出明显差异,优秀运动员组强于普通运动员组。  相似文献   

9.
运动性疲劳对跑运动学与下肢肌电的影响   总被引：2，自引：0，他引：2  
陆阿明  王国栋  王芳 《体育科学》2012,32(6):44-49,80
目的:通过对人体跑至疲劳过程中的运动学与下肢表面肌电图变化特征进行分析,为更好地认识疲劳对人体运动动作的影响提供参考。方法:选取8名男性受试者在跑台上进行12km/h恒速度跑至疲劳,对3个阶段运动学参数及表面肌电时频指标进行单因素方差分析。结果:跑至疲劳的3个阶段,1)单步步长和步频均存在显著性差异(P<0.05),右脚至左脚步长减小(均值为1.68m、1.65m、1.65m),步频增加(均值为2.77步/s、2.84步/s、2.87步/s),而左脚至右脚步长增加(均值为1.61m、1.64m、1.64m),步频减小(均值为2.88步/s、2.84步/s、2.78步/s);2)躯干倾斜、扭转幅度显著增加(P<0.05),髋、膝关节角度出现规律性变化(P<0.05),踝关节角度变化无统计学意义(P>0.05);3)下肢肌积分肌电总体呈上升趋势,不同肌肉平均功率频率指标变化趋势并不一致。结论:中等强度恒速跑至疲劳过程中,随着疲劳的产生与发展:1)从左脚至右脚单步步长增加、步频减慢,而从右脚至左脚出现相反的变化规律,躯干扭转幅度变大,后仰增加,"坐姿"跑成为必然趋势;2)除腓肠肌外,下肢肌肉的积分肌电逐渐增加,平均功率频率呈下降趋势,但左右侧变化的时间段和幅度不完全一致。  相似文献   

10.
结果与分析 第1组的平均比赛速度是5.65m/s,第2组为5.22m/s(见表2)。两组间的平均比赛时间相差略大于7分钟(P<0.001),每公里约差14秒,平均比赛速度相差0.43m/s。第二组比第1组慢7.4％。第1组平均周期速度(5.60±0.27m/s)明显地(P<0.005)快于第2组的平均周期速度(5.23±0.16m/s)。比赛速度与周期速度之间有着显著的相关关系(r=0.89)。两组的周期速率没有差别。第1组为0.84+0.06Hz,第2组为0.82±0.08Hz。第1组与第2组  相似文献   

11.
The purpose of this study was to investigate differences in the support leg joint moment and moment power between side-step (SS) and cross-step (CS) cutting techniques with a prescribed 90° cutting angle. Ground reaction forces (1,000 Hz) and three-dimensional kinematics (250 Hz) of SS and CS cutting techniques were collected from 20 male college athletes. Normalised peak knee extension moment was larger in the SS technique than in the CS technique (0.40 ± 0.10 in SS; 0.26 ± 0.08 in CS). In the SS technique, the knee extensors ( ? 0.10 ± 0.06 in SS; ? 0.02 ± 0.04 in CS) and ankle plantarflexors ( ? 0.12 ± 0.05 in SS; ? 0.07 ± 0.03 in CS) did significantly more negative work (normalised). The direction change angle (40.5 ± 8.7° in SS; 33.0 ± 6.8° in CS) and the decrease in horizontal velocity of the centre of mass ( ? 0.63 ± 0.23 m/s in SS; ? 0.31 ± 0.23 m/s in CS) were significantly larger in the SS technique. These results suggest that the SS technique is an effective means of changing running direction at the expense of velocity of the centre of mass and that the CS technique is better for minimising the reduction in horizontal velocity of the centre of mass.  相似文献   

12.
Abstract

The purpose of this study was to investigate the eccentric torque–velocity and power–velocity relationships of the elbow flexors. Forty recreationally trained individuals (20 men, 20 women) performed maximal eccentric actions at each of five different velocities (1.04 rad · s?1, 2.09 rad · s?1, 3.14 rad · s?1, 4.18 rad · s?1, and 5.23 rad · s?1, in random order) and maximal isometric actions on a Biodex isokinetic dynamometer. A 2×6 (sex×velocity) mixed-factor repeated-measures analysis of variance (ANOVA) was used to assess peak elbow flexor torque during the eccentric and isometric actions. There was no interaction, but there were significant main effects for sex and velocity. Pairwise comparisons demonstrated that values for men were significantly (P<0.05) higher than those for women at all speeds. Furthermore, torques for both sexes were significantly less at 3.14 rad · s?1 (men: 103.94±28.28 N · m; women: 49.24±11.69 N · m) than at 4.18 rad · s?1 (men: 106.39±30.23 N · m; women: 52.77±11.31 N · m) and 5.23 rad · s?1 (men: 108.75±28.59 N · m; women: 53.3±11.67 N · m), while isometric torque was significantly less than at all other speeds (men: 98.66±28.0 N · m; women: 45.25±11.15 N · m). A 2×5 (sex×velocity) mixed-factor repeated-measures ANOVA was used to assess peak eccentric elbow flexor power. There were significant main effects for sex and velocity. Pairwise comparisons demonstrated that values for men were significantly higher than those for women at all speeds. Pairwise comparisons for velocity indicated that peak eccentric power increased across all speeds from 1.04 rad · s?1 (men: 110.44±32.56 W; women 54.36±13.05 W) to 5.23 rad · s?1 (men: 569.46±149.73 W; women: 279.10±61.10 W). These results demonstrate that an increase in velocity had little or no effect on eccentric elbow flexor torque, while eccentric elbow flexor power increased significantly with increases in velocity.  相似文献   

13.
This study investigated how manipulating first step width affects 3D external force production, centre of mass (CoM) motion and performance in athletic sprinting. Eight male and 2 female competitive sprinters (100m PB: 11.03 ± 0.36 s male and 11.6 ± 0.45 s female) performed 10 maximal effort block starts. External force and three-dimensional kinematics were recorded in both the block and first stance phases. Five trials were performed with the athletes performing their preferred technique (Skating) and five trials with the athletes running inside a 0.3 m lane (Narrow). By reducing step width from a mean of 0.31 ± 0.06 m (Skating) to 0.19 ± 0.03 m (Narrow), reductions were found between the two styles in medial block and medial 1st stance impulses, 1st stance anterior toe-off velocity and mediolateral motion of the CoM. No differences were found in block time, step length, stance time, average net resultant force vector, net anteroposterior impulse nor normalised external power. Step width correlated positively with medial impulse but not with braking nor net anteroposterior impulse. Despite less medially directed forces and less mediolateral motion of the CoM in the Narrow trials, no immediate improvement to performance was found by restricting step width.  相似文献   

14.
Critical power is a theoretical concept that presumes there is a certain work‐rate which may be maintained without exhaustion. The extent to which critical power predicts running performance over varying distances has not been determined, and so the aim of this study was to correlate measurements of critical power in the laboratory to running performances in the field at 40 m and 1, 10 and 21.1 km in a group of 17 male longdistance runners (mean ± s.d. age = 31.7 ± 7.3 years). Each subject ran to exhaustion on the treadmill in the laboratory at six different speeds, ranging from 17 to 25 km h‐1. Least squares analyses were used to fit an exponential decay to the relationship between the running speed (y) versus time to exhaustion (x). Critical power was calculated as the running speed (y) coinciding with the asymptote or C parameter of the y = A‐e(‐Bx) + C relationship. The VO2 max was also measured in all subjects. For the data in the field, each subject was timed over 40 m and 1 km and participated in 10‐ and 21.1‐km races. The mean critical power of die subjects in this study was 18.5 ± 1.6 km h‐1. The test‐retest correlation coefficient for the determination of critical power was r = 0.99. The mean VO2 max, measured in a progressive exercise protocol starting at 13 km h‐1 and increasing by 1 km h‐1 every minute, was 59.2 ± 4.6 ml O2 kg‐1 min‐1. The 40‐m times ranged from 5.57 to 6.95 s, the 1‐km times from 2:46 to 3:55 min:s, the 10‐km times from 30:43 to 42:02 min:s and the 21‐km times from 67:00 to 95:45 min:s. Critical power predicted running times over 1 km (r = ‐0.75, P< 0.001), 10 km (r = ‐ 0.85, P< 0.00001) and 21.1 km (r = ‐ 0.79, P< 0.001) in this heterogeneous group of runners. The correlation coefficients for VO2 max and running performances were similar to the above at all distances. Even in the best relationship between critical power and the time taken to run 10 km, only 72% of the variation in the 10‐km running time could be accounted for by differences in critical power. While the test of critical power may be repeatable and correlate significantly with VO2 max (r = 0.77, P< 0.001), the measurement lacks the degree of specificity required to predict running performance in trained subjects of varying ability.  相似文献   

15.
Negative work, which is mainly generated by eccentric muscle contraction, has an important influence on the associated muscle damage. Generally, mechanical parameters are determined for one side of a lower extremity on the assumption of negligible between-limb differences. However, between-limb differences in the negative work of lower extremity joints during running remain unclear. This study examines between-limb differences in negative work and associated mechanical parameters during the contact phase of running. Twenty-five young adult males voluntarily participated in this study. Each participant was asked to run on a straight runway at a speed of 3.0?m?s?1. Negative work, amplitude, duration of negative power, moment, and angular velocity were computed for both sides of the lower extremities. Significant differences were found in negative work between limbs for the hip (18.9?±?11.7%), knee (13.6?±?10.4%), and ankle (11.8?±?8.5%) joints. For the hip joint, asymmetric negative work was attributable to the between-limb difference in the amplitude of negative power owing to a corresponding difference in the moment. The between-limb differences concerning the duration and amplitude of negative power could explain the asymmetric negative work in the knee joint. The asymmetric negative work of the ankle joint was attributable to the between-limb difference in the amplitude and duration of the negative power and the moment. These results indicate that asymmetric negative work was generated in each lower extremity joint; however, the major mechanical parameters corresponding to the negative work are not the same across the joints.  相似文献   

16.
Athletes in inner lanes may be disadvantaged during athletic sprint races containing a bend portion because of the tightness of the bend. We empirically investigated the veracity of modelled estimates of this disadvantage and the effect of running lane on selected kinematic variables. Three-dimensional video analysis was conducted on nine male athletes in lanes 8, 5 and 2 of the bend of an outdoor track (radii: 45.10, 41.41 and 37.72 m, respectively). There was over 2% (p < 0.05) reduction in mean race velocity from lane 8 (left step 9.56 ± 0.43 m/s, right step: 9.49 ± 0.41 m/s) to lane 5 (left step: 9.36 ± 0.51 m/s, right step: 9.30 ± 0.51 m/s), with only slight further reductions from lane 5 to lane 2 (left step: 9.34 ± 0.61 m/s, right step: 9.30 ± 0.63 m/s). Race velocity decreased mainly because of reductions in step frequency as radius decreased. These unique data demonstrate the extent of the disadvantage of inner lane allocation during competition may be greater than previously suspected. Variations in race velocity changes might indicate some athletes are better able to accommodate running at tighter radii than others, which should have implications for athletes’ training.  相似文献   

17.
This study aimed to compare the power produced by the flutter-kick action at different swimming velocities. Eighteen high-level male swimmers completed a maximal 15-m flutter-kicking sprint and underwent two tests (one passive and one with maximal flutter-kicking) in which they were towed at six velocities ranging from 1.0 to 2.0 m/s. Power values were computed for each velocity, and selected kinematic indices were evaluated at 1.2 and 2.0 m/s. The highest power (54 ± 8 W) was observed at the velocity at which the drag equaled the propulsive force (1.27 ± 0.08 m/s), which was similar to that recorded in the flutter-kicking sprint (1.26 ± 0.09 m/s). Thereafter, power decreased significantly with increasing velocity, up to 17 ± 10 W (at 2.0 m/s). The angle between the horizontal and the line connecting the highest and lowest points of the malleolus trajectory was significantly wider at 1.2 m/s than at 2.0 m/s (75 ± 4° vs. 63 ± 6°). This could explain the change of power with velocity because all the other kinematic indices considered were similar at the two velocities. These results suggest that the propulsive role of the flutter-kick increases as the swimming velocity decreases.  相似文献   

18.
Abstract

This study investigated the interaction between emotion-eliciting pictures and power output during a repetitive supra-maximal task on a cycle ergometre. Twelve male participants (mean (±SD) age, height and weight: 28.58 ± 3.23 years, 1.78 ± 0.05 m and 82.41 ± 13.29 kg) performed 5 repeated sprint tests on a cycle ergometre in front of neutral, pleasant or unpleasant pictures. For each sprint, mechanical (peak power and work), physiological (heart rate) and perceptual (affective load) indices were analysed. Affective load was calculated from the ratings of perceived exertion, which reflected the amount of pleasant and unpleasant responses experienced during exercise. The results showed that peak power, work and heart rate values were significantly lower (P < 0.05) for unpleasant pictures (9.18 ± 0.20 W ? kg?1; 47.69 ± 1.08 J ? kg?1; 152 ± 4 bpm) when compared with pleasant ones (9.50 ± 0.20 W ? kg?1; 50.11 ± 0.11 J ? kg?1; 156 ± 3 bpm). Furthermore, the affective load was found to be similar for the pleasant and unpleasant sessions. All together, these results suggested that the ability to produce maximal power output depended on whether the emotional context was pleasant or unpleasant. The fact that the power output was lower in the unpleasant versus pleasant session could reflect a regulatory process aimed at maintaining a similar level of affective load for both sessions.  相似文献   

19.
The aim of this study was to examine the impact of contextual factors on relative locomotor and metabolic power distances during professional female soccer matches. Twenty-eight players (forwards, n?=?4; midfielders, n?=?12; defenders, n?=?12) that competed in a 90-min home and away match (regular season only). The generalised estimating equations (GEE) was used to evaluate relative locomotor and metabolic power distances for three contextual factors: location (home vs. away), type of turf (natural vs. artificial), and match outcome (win, loss and draw). No differences were observed for home vs. away matches. Moderate-intensity running (20.0?±?1.0?m?min?1 and 16.4?±?0.9?m?min?1), high-intensity running (8.6?±?0.4?m?min?1 and 7.3?±?0.4?m?min?1) and high-metabolic power (16.3?±?0.5?m?min?1 and 14.4?±?0.5?m?min?1) distances were elevated on artificial turf compared to natural grass, respectively. Relative sprint distance was greater during losses compared with draws (4.3?±?0.4?m?min?1 and 3.4?±?0.3?m?min?1). Overall physical demands of professional women’s soccer were not impacted by match location. However, the elevation of moderate and high-intensity demands while playing on artificial turf may have implications on match preparations as well as recovery strategies.  相似文献   

20.
Abstract

In an effort to investigate the force-time characteristics during the acceleration phase of the sprint start, eight male sprinters were used as subjects. Runs up to 3 m were analyzed from film, and force-time parameters were measured on a force platform. In a starting stance the reaction time of the group was .118 ± .016 s and the force production lasted .342 ± .022 s. The maximal resultant force at the moment of maximal horizontal force was 19.3 ± 2.2 N x kg1, and the direction of the force was 32 ± 7°. In the very last instant before leaving the blocks the velocity of the center of gravity was 3.46 ± .32 m x s?1. In the first contact after leaving the blocks there was a braking phase (.022 ± .005 s in duration) during which the average horizontal force was ?153 ± 67 N. The braking phase was observed despite the body center of gravity being horizontally ahead by .13 ± . 05 m with respect to the first contact point. The percentage of deceleration in running velocity during that phase was 4.8 ± 2.9%. In the propulsion phase the average horizontal force was great (526 ± 75 N), and it was produced for a relatively long time (.171 ± .035 s). Significant correlation coefficients were observed between force production and running velocity. These results suggest that braking/propulsion phases occur immediately after the block phase and that muscle strength strongly affects running velocity in the sprint start.  相似文献   

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