The EMG, NIRS, and RPE responses to two turn transition techniques in alpine skiing

JSAMS plus Pub Date : 2023-01-01 DOI:10.1016/j.jsampl.2023.100037

John G. Seifert , Ronald W. Kipp , Shannon Griffin , David Graham

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Abstract

Objective

Two techniques facilitate the transition in an alpine ski turn, extension (EXT) and flexion (FLEX). The purpose of this study is to compare NIRS, EMG, and RPE responses between EXT and FLEX in expert level skiers.

Design

24 Professional Ski Instructors of America Level III alpine ski instructors, examiners, and National Demonstration Team members completed one standardized run each of EXT and FLEX. A turn cycle, made of a right and left turn, was divided into four Phases.

Methods

NIRS assessed HbO2 desaturation in the rectus femoris (RF) and vastus lateralis (VL). EMG was collected from the RF, VL, and gluteus medius (GM). Rating of Perceived Exertion (RPE, 0–10) assessed subjective exertion.

Results

FLEX resulted in greater HbO2 desaturation in RF (−77.9 ± 21% vs. −67.5 ± 23%, p < 0.001), VL (−69.8 ± 23.1% vs. −61.1 ± 24.6%, p < 0.001) and RPE (6.0 ± 2.3 vs. 5.2 ± 2.0, p < 0.001) compared to EXT. FLEX generally resulted in greater EMG activity in the steering and transition phases for RF and VL (p < 0.001) while EXT resulted in greater activity GM on the inside leg.

Conclusions

Caution should be exercised with recreational skiers as the FLEX transition resulted in significantly greater physiological stress compared to EXT. Localized hypoxia appears to be the focal point of this stress as HbO₂ desaturation was ∼15% greater along with 15% greater RPE during FLEX. FLEX also produced greater EMG activity than EXT in the majority of the turn phases.

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高山滑雪两种转弯转换技术的EMG、NIRS和RPE反应

目的两种技术有助于高山滑雪转弯的过渡，伸展（EXT）和屈曲（FLEX）。本研究的目的是比较专家级滑雪者EXT和FLEX的NIRS、EMG和RPE反应。Design24名美国专业滑雪教练三级高山滑雪教练、考官和国家示范队成员分别完成了EXT和FLEX的一次标准化跑步。由右转和左转组成的转弯循环分为四个阶段。方法NIRS检测股直肌（RF）和股外侧肌（VL）的HbO2饱和度。从RF、VL和臀中肌（GM）采集EMG。感知用力评分（RPE，0-10）评估主观用力。结果FLEX可使RF中的HbO2去饱和度增加（−77.9±21%对-67.5±23%，p<；0.001），VL（−69.8±23.1%对-61.1±24.6%，p<；0.001）和RPE（6.0±2.3与5.2±2.0，p<；0.001）。FLEX通常在RF和VL的转向和过渡阶段导致更大的EMG活动（p<；0.001），而EXT在内侧腿上产生更大的活性GM。结论娱乐性滑雪者应谨慎，因为与EXT相比，FLEX过渡会导致明显更大的生理压力。局部缺氧似乎是这种压力的焦点，因为在FLEX过程中，HbO2去饱和度增加了～15%，RPE增加了15%。在大多数转弯阶段，FLEX也比EXT产生更大的EMG活动。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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