Hader Karim, Mendez-Villanueva Alberto, Palazzi Dino, Ahmaidi Saïd, Buchheit Martin
Laboratory of Exercise Physiology and Rehabilitation, EA 3300, Faculty of Sport Sciences, University of Picardie, Jules Verne, 80025 Amiens, France.
National Sports Medicine Programme, Excellence in Football Project, Aspetar-Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
PLoS One. 2016 Mar 1;11(3):e0149839. doi: 10.1371/journal.pone.0149839. eCollection 2016.
The aims of this study were to 1) compare the metabolic power demand of straight-line and change of direction (COD) sprints including 45° or 90°-turns, and 2) examine the relation between estimated metabolic demands and muscular activity throughout the 3 phases of COD-sprints.
Twelve highly-trained soccer players performed one 25-m and three 20-m sprints, either in straight-line or with one 45°- or 90°-COD. Sprints were monitored with 2 synchronized 100-Hz laser guns to assess players' velocities before, during and after the COD. Acceleration and deceleration were derived from changes in speed over time. Metabolic power was estimated based on di Prampero's approach (2005). Electromyography amplitude (RMS) of 2 lower limb muscles was measured. The expected energy expenditure during time-adjusted straight-line sprints (matching COD sprints time) was also calculated.
Locomotor-dependant metabolic demand was largely lower with COD (90°, 142.1±13.5 J.kg(-1)) compared with time-adjusted (effect size, ES = -3.0; 193.2±18.6 J.kg(-1)) and non-adjusted straight-line sprints (ES = -1.7; 168.4±15.3 J.kg(-1)). Metabolic power requirement was angle-dependent, moderately lower for 90°-COD vs. 45°-COD sprint (ES = -1.0; 149.5±10.4 J.kg(-1)). Conversely, the RMS was slightly- (45°, ES = +0.5; +2.1%, 90% confidence limits (±3.6) for vastus lateralis muscle (VL)) to-largely (90°, ES = +1.6; +6.1 (3.3%) for VL) greater for COD-sprints. Metabolic power/RMS ratio was 2 to 4 times lower during deceleration than acceleration phases.
Present results show that COD-sprints are largely less metabolically demanding than linear sprints. This may be related to the very low metabolic demand associated with the deceleration phase during COD-sprints that may not be compensated by the increased requirement of the reacceleration phase. These results also highlight the dissociation between metabolic and muscle activity demands during COD-sprints, which questions the use of metabolic power as a single measure of running load in soccer.
本研究的目的是：1）比较直线冲刺和包括45°或90°转弯的变向（COD）冲刺的代谢功率需求；2）研究在COD冲刺的三个阶段中，估计的代谢需求与肌肉活动之间的关系。
12名训练有素的足球运动员进行一次25米和三次20米的冲刺，冲刺方式为直线冲刺或一次45°或90°的COD冲刺。使用2台同步的100赫兹激光枪监测冲刺过程，以评估运动员在COD之前、期间和之后的速度。加速度和减速度由速度随时间的变化得出。代谢功率根据迪·普拉姆佩罗（di Prampero）的方法（2005年）进行估计。测量了2条下肢肌肉的肌电图幅度（均方根值，RMS）。还计算了时间调整后的直线冲刺（与COD冲刺时间匹配）期间的预期能量消耗。
与时间调整后的（效应量，ES = -3.0；193.2±18.6焦耳·千克⁻¹）和未调整的直线冲刺（ES = -1.7；168.4±15.3焦耳·千克⁻¹）相比，COD（90°，142.1±13.5焦耳·千克⁻¹）的运动相关代谢需求要低得多。代谢功率需求与角度有关，90°COD冲刺比45°COD冲刺的代谢功率需求适度降低（ES = -1.0；149.5±10.4焦耳·千克⁻¹）。相反，对于COD冲刺，外侧股四头肌（VL）的RMS略有增加（45°，ES = +0.5；+2.1%，90%置信区间（±3.6））到大幅增加（90°，ES = +1.6；+6.1（3.3%））。减速阶段的代谢功率/RMS比值比加速阶段低2至4倍。
目前的结果表明，COD冲刺的代谢需求在很大程度上低于直线冲刺。这可能与COD冲刺减速阶段极低的代谢需求有关，而加速阶段增加的需求可能无法弥补这一需求。这些结果还突出了COD冲刺期间代谢需求与肌肉活动需求之间的分离，这对将代谢功率作为足球运动负荷的单一衡量标准提出了质疑。
