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

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Alpine ski turns utilize extension (EXT) and flexion (FLEX) techniques for transitions.
• Understanding the physiological demands of these techniques is crucial for performance and injury prevention.

Purpose of the Study:

• To compare physiological responses, including muscle oxygenation (NIRS), muscle activity (EMG), and perceived exertion (RPE), between EXT and FLEX techniques in expert skiers.

Main Methods:

• Twenty-four elite alpine skiers performed standardized EXT and FLEX turns.
• Non-invasive near-infrared spectroscopy (NIRS) measured HbO2 desaturation in the rectus femoris (RF) and vastus lateralis (VL).
• Electromyography (EMG) recorded muscle activity from RF, VL, and gluteus medius (GM), alongside Rating of Perceived Exertion (RPE).

Main Results:

• Flexion (FLEX) induced significantly greater HbO2 desaturation in RF and VL compared to extension (EXT).
• FLEX also resulted in higher RPE and increased EMG activity in RF and VL during steering and transition phases.
• Extension (EXT) showed greater gluteus medius (GM) activity on the inside leg.

Conclusions:

• Flexion (FLEX) imposes a greater physiological load on skiers than extension (EXT), characterized by localized hypoxia and higher exertion.
• The findings suggest that recreational skiers should exercise caution with FLEX transitions due to increased physiological stress.
• FLEX transitions are associated with heightened muscle deoxygenation and EMG activity, highlighting their demanding nature.