University of "Tor Vergata", Rome, Italy.
J Strength Cond Res. 2013 Jul;27(7):1964-73. doi: 10.1519/JSC.0b013e3182752d5e.
The aim of this study was to investigate the effects of gradients (0, 2, and 7%) on biomechanical parameters during racewalking (RW) at iso-efficiency speed (IES). During the experiment, 12 high-level athletes performed at IES on different slopes. The parameters studied were surface muscular activity (EMG) of 5 muscles of the leg using Muscle Lab (Boscosystem); kinematic parameters were collected using a high-speed camera (210 Hz) analyzed with Dartfish 5.5 Pro; and heart rate (HR) was monitored with a Cardio Polar. The results showed step length (SL), step frequency (SF), and internal work (WINT) decreased with increased treadmill gradient: SL = ([0-2% = 3.48%, p = 0.158], [0-7% = 12.17%, p < 0.001]); SF = ([0-2% = 2.38%, p = 0.173], [0-7% = 6.07%, p < 0.01]); WINT = ([0-2% = 8.34%, p < 0.001], [0-7% = 22.81%, p < 0.0001]). Conversely, contact time (CT) and HR increased less significantly with the increased gradients: CT = ([0-2% = 2.46%, p = 0.198], [0-7% = 6.56%, p < 0.01]); HR = ([0-2% = 0.62%, p = 0.652], [0-7% = 3.25%, p < 0.05]). The knee angle (KE) increased, whereas ankle angle (AK) and hip angle (HP) decreased with the increased gradients: AK = ([0-2% = 1.69%, p < 0.001], [0-7% = 1.13%, p < 0.01]); HP = ([0-2% = 0.22%, p < 0.03], [0-7% = 0.16%, p = 0.456]); KE = ([0-2% = 1.01%, p < 0.001], [0-7% = 1.60%, p < 0.001]). Electromyography (EMG) significantly decreased with the increased gradients in the: tibialis anterior ([0-2% = 22.49%, p < 0.0001], [0-7% = 41.18%, p < 0.0001]) and rectus femoris ([0-2% = 15.35%, p < 0.0001], [0-7% = 29.13%, p< 0.0001]). In contrast, EMG activity was significantly increased in the vastus lateralis ([0-2% = 22.95%, p < 0.0001], [0-7% = 31.15%, p < 0.0001]), gastrocnemius medialis ([0-2% = 21.40%, p < 0.001], [0-7% = 48.37%, p < 0.0001]), and biceps femoris ([0-2% = 190.78%, p < 0.0001], [0-7% = 201.37%, p < 0.0001]). The results indicate that increasing the gradient to 2% did not elicit an increased HR in racewalkers; however, at a 7% gradient, greater muscle activity was required.
本研究旨在探讨在等效率速度（IES）下，不同坡度（0、2 和 7%）对竞走运动生物力学参数的影响。在实验中，12 名高水平运动员在不同坡度的跑步机上以 IES 速度进行运动。研究的参数包括使用 Muscle Lab（Boscosystem）测量的腿部 5 块肌肉的表面肌电（EMG）；使用高速摄像机（210Hz）采集运动学参数，并使用 Dartfish 5.5 Pro 进行分析；以及使用 Cardio Polar 监测心率（HR）。结果表明，随着跑步机坡度的增加，步长（SL）、步频（SF）和内功（WINT）减少：SL = ([0-2%=3.48%，p=0.158]，[0-7%=12.17%，p<0.001]）；SF = ([0-2%=2.38%，p=0.173]，[0-7%=6.07%，p<0.01]）；WINT = ([0-2%=8.34%，p<0.001]，[0-7%=22.81%，p<0.0001]）。相反，随着坡度的增加，接触时间（CT）和 HR 增加不明显：CT = ([0-2%=2.46%，p=0.198]，[0-7%=6.56%，p<0.01]）；HR = ([0-2%=0.62%，p=0.652]，[0-7%=3.25%，p<0.05]）。随着坡度的增加，膝关节角度（KE）增加，而踝关节角度（AK）和髋关节角度（HP）减小：AK = ([0-2%=1.69%，p<0.001]，[0-7%=1.13%，p<0.01]）；HP = ([0-2%=0.22%，p<0.03]，[0-7%=0.16%，p=0.456]）；KE = ([0-2%=1.01%，p<0.001]，[0-7%=1.60%，p<0.001]）。随着坡度的增加，肌电图（EMG）在：胫骨前肌（[0-2%=22.49%，p<0.0001]，[0-7%=41.18%，p<0.0001]）和股直肌（[0-2%=15.35%，p<0.0001]，[0-7%=29.13%，p<0.0001]）中显著降低。相反，股外侧肌（[0-2%=22.95%，p<0.0001]，[0-7%=31.15%，p<0.0001]）、内侧腓肠肌（[0-2%=21.40%，p<0.001]，[0-7%=48.37%，p<0.0001]）和股二头肌（[0-2%=190.78%，p<0.0001]，[0-7%=201.37%，p<0.0001]）的 EMG 活性显著增加。结果表明，在 2%的坡度下，竞走运动员的 HR 不会增加；然而，在 7%的坡度下，需要更大的肌肉活动。
