Walsh Joel A, McAndrew Darryl J, Shemmell Jonathan, Stapley Paul J
Neural Control of Movement Laboratory, School of Medical, Indigenous and Health Sciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW, Australia.
Graduate School of Medicine, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW, Australia.
Front Physiol. 2022 Jul 8;13:953517. doi: 10.3389/fphys.2022.953517. eCollection 2022.
Submaximal eccentric (ECC) cycling exercise is commonly used in research studies. No previous study has specified the required time naïve participants take to familiarize with submaximal ECC cycling. Therefore, we designed this study to determine whether critical indicators of cycling reliability and variability stabilize during 15 min of submaximal, semi-recumbent ECC cycling (ECC cycling). Twenty-two participants, aged between 18-51 years, volunteered to complete a single experimental session. Each participant completed three peak eccentric torque protocol (PETP) tests, nine countermovement jumps and 15 min of submaximal (i.e., 10% peak power output produced during the PETP tests) ECC cycling. Muscle activation patterns were recorded from six muscles (rectus femoris, RF; vastus lateralis, VL; vastus medialis, VM; soleus, SOL; medial gastrocnemius, GM; tibialis anterior, TA), during prescribed-intensity ECC cycling, using electromyography (EMG). Minute-to-minute changes in the reliability and variability of EMG patterns were examined using intra-class correlation coefficient (ICC) and variance ratios (VR). Differences between target and actual power output were also used as an indicator of familiarization. Activation patterns for 4/6 muscles (RF, VL, VM and GM) became more consistent over the session, the RF, VL and VM increasing from moderate (ICC = 0.5-0.75) to good (ICC = 0.75-0.9) reliability by the 11th minute of cycling and the GM good reliability from the 1st minute (ICC = 0.79, ICC range = 0.70-0.88). Low variability (VR ≤ 0.40) was maintained for VL, VM and GM from the 8th, 8th and 1st minutes, respectively. We also observed a significant decrease in the difference between actual and target power output (χ = 30.895, = 0.006, = 0.105), expressed primarily between the 2nd and 3rd minute of cycling ( = -2.677, = 0.007). Indicators of familiarization during ECC cycling, including deviations from target power output levels and the reliability and variability of muscle activation patterns stabilized within 15 min of cycling. Based upon this data, it would be reasonable for future studies to allocate ∼ 15 min to familiarize naïve participants with a submaximal ECC cycling protocol.
次最大强度离心（ECC）骑行运动常用于研究。此前尚无研究明确指出初次参与的受试者熟悉次最大强度ECC骑行所需的时间。因此，我们设计了本研究，以确定在15分钟的次最大强度、半卧位ECC骑行（ECC骑行）过程中，骑行可靠性和变异性的关键指标是否会趋于稳定。22名年龄在18至51岁之间的参与者自愿完成一次实验。每位参与者完成了三项峰值离心扭矩方案（PETP）测试、九次反向跳跃以及15分钟的次最大强度（即PETP测试期间产生的峰值功率输出的10%）ECC骑行。在规定强度的ECC骑行过程中，使用肌电图（EMG）记录了六块肌肉（股直肌，RF；股外侧肌，VL；股内侧肌，VM；比目鱼肌，SOL；腓肠肌内侧头，GM；胫骨前肌，TA）的肌肉激活模式。使用组内相关系数（ICC）和方差比（VR）检查EMG模式可靠性和变异性的逐分钟变化。目标功率输出与实际功率输出之间的差异也被用作熟悉程度的指标。在整个过程中，6块肌肉中的4块（RF、VL、VM和GM）的激活模式变得更加一致，在骑行第11分钟时，RF、VL和VM的可靠性从中等（ICC = 0.5 - 0.75）提高到良好（ICC = 0.75 - 0.9），GM从第1分钟起就具有良好的可靠性（ICC = 0.79，ICC范围 = 0.70 - 0.88）。VL、VM和GM分别从第8分钟、第8分钟和第1分钟起保持低变异性（VR≤0.40）。我们还观察到实际功率输出与目标功率输出之间的差异显著降低（χ = 30.895， = 0.006， = 0.105），主要表现在骑行的第2分钟和第3分钟之间（ = -2.677， = 0.007）。ECC骑行过程中的熟悉程度指标，包括与目标功率输出水平的偏差以及肌肉激活模式的可靠性和变异性，在骑行15分钟内趋于稳定。基于这些数据，未来的研究合理分配约15分钟时间，让初次参与的受试者熟悉次最大强度ECC骑行方案是合理的。
