Ridard Jade, Rozand Vianney, Millet Guillaume Y, Lapole Thomas
Laboratoire Interuniversitaire de Biologie de la Motricité, UJM Saint-Etienne, University Lyon, SAINT-ETIENNE, France.
Institut Universitaire de France (IUF), Paris, France.
Front Physiol. 2022 Nov 9;13:1039616. doi: 10.3389/fphys.2022.1039616. eCollection 2022.
Monitoring fatigue is now commonly performed in athletes as it can directly impact performance and may further increase the risk of injury or overtraining syndrome. Among the exercise-induced peripheral alterations, low-frequency fatigue (LFF) assessment is commonly restricted to in-lab studies. Measuring LFF on-field would allow athletes and coaches to assess muscle fatigability on a regular basis. The aim of the present study was therefore to validate a new portable device allowing quadriceps LFF assessment in the field. LFF was assessed in 15 active and healthy participants before (PRE) and after (POST) a series of drop jumps. LFF was assessed, thanks to a dedicated device recording evoked force to muscle submaximal electrical low- and high-frequency stimulation. Changes in the low- to high-frequency force ratio (further referred to as Powerdex value) were compared to the changes in the ratio of evoked force induced by paired-pulse femoral nerve electrical stimulation at 10 and 100 Hz (i.e., DB10/DB100 ratio). Maximal voluntary contraction (MVC) and voluntary activation (VA) were also measured. MVC decreased ( < 0.001), whereas VA was not affected by the fatiguing task ( = 0.14). There was a decrease in the DB10/DB100 ratio (from 96.4% to 67.3%, < 0.001) as well as in the Powerdex value (from 74.0% to 55.7%, < 0.001). There was no significant difference between POST values (expressed in percentage of PRE values) of the DB10/DB100 ratio and Powerdex ( = 0.44), and there was a significant correlation between the changes in Powerdex and DB10/DB100 (r = 0.82, < 0.001). The on-field device we tested is a valid tool to assess LFF after a strenuous exercise consisting of repeated drop jumps as it evidences the presence of LFF similarly to a lab technique. Such a device can be used to monitor muscle fatigability related to excitation-contraction in athletes.
目前，对运动员进行疲劳监测很常见，因为疲劳会直接影响运动表现，还可能进一步增加受伤或过度训练综合征的风险。在运动引起的外周变化中，低频疲劳（LFF）评估通常仅限于实验室研究。在现场测量LFF将使运动员和教练能够定期评估肌肉的疲劳能力。因此，本研究的目的是验证一种新的便携式设备，该设备可在现场评估股四头肌的LFF。在15名活跃且健康的参与者进行一系列纵跳之前（PRE）和之后（POST），对其LFF进行评估。借助一种专门的设备记录肌肉在亚最大电低频和高频刺激下诱发的力量，来评估LFF。将低频与高频力量比值（以下简称Powerdex值）的变化与在10Hz和100Hz下由双脉冲股神经电刺激诱发的力量比值变化（即DB10/DB100比值）进行比较。还测量了最大自主收缩（MVC）和自主激活（VA）。MVC降低（<0.001），而VA不受疲劳任务的影响（=0.14）。DB10/DB100比值（从96.4%降至67.3%，<0.001）以及Powerdex值（从74.0%降至55.7%，<0.001）均有所下降。DB10/DB100比值和Powerdex的POST值（以PRE值的百分比表示）之间无显著差异（=0.44），且Powerdex和DB10/DB100的变化之间存在显著相关性（r=0.82，<0.001）。我们测试的现场设备是评估由重复纵跳组成的剧烈运动后LFF的有效工具，因为它与实验室技术一样能证明LFF的存在。这种设备可用于监测运动员与兴奋收缩相关的肌肉疲劳能力。
