Institute of Biomedical Sciences, Department of Biomechanics of University School of Physical Education in Cracow, Poland.
Institute of Biomedical Sciences, Department of Physiology and Biochemistry of University School of Physical Education in Cracow, Poland.
J Hum Kinet. 2014 Dec 30;44:129-36. doi: 10.2478/hukin-2014-0118. eCollection 2014 Dec 9.
The aim of the study was to assess energy cost and total external work (total energy) depending on the speed of race walking. Another objective was to determine the contribution of external work to total energy cost of walking at technical, threshold and racing speed in elite competitive race walkers. The study involved 12 competitive race walkers aged 24.9 4.10 years with 6 to 20 years of experience, who achieved a national or international sports level. Their aerobic endurance was determined by means of a direct method involving an incremental exercise test on the treadmill. The participants performed three tests walking each time with one of the three speeds according to the same protocol: an 8-minute walk with at steady speed was followed by a recovery phase until the oxygen debt was repaid. To measure exercise energy cost, an indirect method based on the volume of oxygen uptake was employed. The gait of the participants was recorded using the 3D Vicon opto-electronic motion capture system. Values of changes in potential energy and total kinetic energy in a gate cycle were determined based on vertical displacements of the centre of mass. Changes in mechanical energy amounted to the value of total external work of muscles needed to accelerate and lift the centre of mass during a normalised gait cycle. The values of average energy cost and of total external work standardised to body mass and distance covered calculated for technical speed, threshold and racing speeds turned out to be statistically significant (p 0.001). The total energy cost ranged from 51.2 kJ.m-1 during walking at technical speed to 78.3 kJ.m-1 during walking at a racing speed. Regardless of the type of speed, the total external work of muscles accounted for around 25% of total energy cost in race walking. Total external work mainly increased because of changes in the resultant kinetic energy of the centre of mass movement.
这项研究的目的是评估竞走速度对能量消耗和总外功（总能量）的影响。另一个目的是确定在技术速度、门槛速度和竞赛速度下，外功对竞走总能量消耗的贡献。研究对象为 12 名年龄为 24.9 4.10 岁、经验 6-20 年的竞技竞走运动员，他们都达到了国家或国际运动水平。他们的有氧耐力通过在跑步机上进行递增运动测试的直接方法确定。参与者每次以三种速度中的一种进行三次测试，每次测试都遵循相同的协议：以稳定速度进行 8 分钟行走，然后进行恢复阶段，直到氧债偿还。为了测量运动能量消耗，采用了基于耗氧量的间接方法。参与者的步态使用 3D Vicon 光电运动捕捉系统进行记录。根据质心的垂直位移，确定一个步态周期内势能和总动能变化的值。机械能的变化等于在正常步态周期中加速和提升质心所需的肌肉总外力功的值。技术速度、门槛速度和竞赛速度下平均能量消耗和总外功标准化到体重和距离的值均具有统计学意义（p 0.001）。技术速度下行走的能量消耗平均值为 51.2 kJ.m-1，竞赛速度下行走的能量消耗平均值为 78.3 kJ.m-1。无论速度类型如何，肌肉的总外功都占竞走总能量消耗的约 25%。总外功主要是由于质心运动的合力动能变化而增加。
