Quarmby Andrew, Khajooei Mina, Kurtz Philip, Henschke Jakob, Kim MyoungHwee, Mayer Frank, Engel Tilman
University Outpatient Clinic, Sports Medicine & Sports Orthopaedics, University of Potsdam, Potsdam, Germany.
Front Sports Act Living. 2023 Mar 15;5:1129058. doi: 10.3389/fspor.2023.1129058. eCollection 2023.
Balance is vital for human health and experiments have been conducted to measure the mechanisms of postural control, for example studying reflex responses to simulated perturbations. Such studies are frequent in walking but less common in running, and an understanding of reflex responses to trip-like disturbances could enhance our understanding of human gait and improve approaches to training and rehabilitation. Therefore, the primary aim of this study was to investigate the technical validity and reliability of a treadmill running protocol with perturbations. A further exploratory aim was to evaluate the associated neuromuscular reflex responses to the perturbations, in the lower limbs.
Twelve healthy participants completed a running protocol (9 km/h) test-retest (2 weeks apart), whereby 30 unilateral perturbations were executed via the treadmill belts (presets:2.0 m/s amplitude;150 ms delay (post-heel contact);100ms duration). Validity of the perturbations was assessed via mean ± SD comparison, percentage error calculation between the preset and recorded perturbation characteristics (PE%), and coefficient of variation (CV%). Test-retest reliability (TRV%) and Bland-Altman analysis (BLA; bias ± 1.96 * SD) was calculated for reliability. To measure reflex activity, electromyography (EMG) was applied in both legs. EMG amplitudes (root mean square normalized to unperturbed strides) and latencies [ms] were analysed descriptively.
Left-side perturbation amplitude was 1.9 ± 0.1 m/s, delay 105 ± 2 ms, and duration 78 ± 1 ms. Right-side perturbation amplitude was 1.9 ± 0.1 m/s, delay 118 ± 2 ms, duration 78 ± 1 ms. PE% ranged from 5-30% for the recorded perturbations. CV% of the perturbations ranged from 19.5-76.8%. TRV% for the perturbations was 6.4-16.6%. BLA for the left was amplitude: 0.0 ± 0.3m/s, delay: 0 ± 17 ms, duration: 2 ± 13 ms, and for the right was amplitude: 0.1 ± 0.7, delay: 4 ± 40 ms, duration: 1 ± 35 ms. EMG amplitudes ranged from 175 ± 141%-454 ± 359% in both limbs. Latencies were 109 ± 12-116 ± 23 ms in the tibialis anterior, and 128 ± 49-157 ± 20 ms in the biceps femoris.
Generally, this study indicated sufficient validity and reliability of the current setup considering the technical challenges and limitations, although the reliability of the right-sided perturbations could be questioned. The protocol provoked reflex responses in the lower extremities, especially in the leading leg. Acute neuromusculoskeletal adjustments to the perturbations could be studied and compared in clinical and healthy running populations, and the protocol could be utilised to monitor chronic adaptations to interventions over time.
平衡对人类健康至关重要，人们已开展实验来测量姿势控制机制，例如研究对模拟扰动的反射反应。此类研究在步行中很常见，但在跑步中较少见，而了解对类似绊倒干扰的反射反应有助于增强我们对人类步态的理解，并改进训练和康复方法。因此，本研究的主要目的是调查带有扰动的跑步机跑步方案的技术有效性和可靠性。另一个探索性目的是评估下肢对扰动的相关神经肌肉反射反应。
12名健康参与者完成了一项跑步方案（9公里/小时）的重测（间隔2周），通过跑步机皮带进行30次单侧扰动（预设：振幅2.0米/秒；延迟150毫秒（足跟接触后）；持续时间100毫秒）。通过均值±标准差比较、预设与记录的扰动特征之间的百分比误差计算（PE%）以及变异系数（CV%）来评估扰动的有效性。计算重测可靠性（TRV%）和布兰德-奥特曼分析（BLA；偏差±1.96*标准差）以评估可靠性。为测量反射活动，在双腿上应用了肌电图（EMG）。对EMG振幅（均方根归一化至未受扰动的步幅）和潜伏期[毫秒]进行描述性分析。
左侧扰动振幅为1.9±0.1米/秒，延迟105±2毫秒，持续时间78±1毫秒。右侧扰动振幅为1.9±0.1米/秒，延迟118±2毫秒，持续时间78±1毫秒。记录的扰动的PE%范围为5 - 30%。扰动的CV%范围为19.5 - 76.8%。扰动的TRV%为6.4 - 16.6%。左侧的BLA为振幅：0.0±0.3米/秒，延迟：0±17毫秒，持续时间：2±13毫秒，右侧的为振幅：0.1±0.7，延迟：4±40毫秒，持续时间：1±35毫秒。双腿的EMG振幅范围为175±141% - 454±359%。胫骨前肌的潜伏期为109±12 - 116±23毫秒，股二头肌的潜伏期为128±49 - 157±20毫秒。
总体而言，考虑到技术挑战和局限性，本研究表明当前设置具有足够的有效性和可靠性，尽管右侧扰动的可靠性可能受到质疑。该方案引发了下肢的反射反应，尤其是在前导腿中。可以在临床和健康跑步人群中研究和比较对扰动的急性神经肌肉骨骼调整，并且该方案可用于监测随时间对干预的慢性适应性变化。
