A Comprehensive Comparison and Validation of Published Methods to Detect Turn Switch during Alpine Skiing

Area of Science:

• Biomechanics
• Sports Technology
• Performance Analysis

Background:

• Determining the exact moment of turn switch (TS) in alpine skiing is crucial for performance analysis.
• Numerous methods and sensor types exist for TS detection, but a clear consensus on the best approach is lacking.
• This variability makes it difficult to compare results across different studies.

Purpose of the Study:

• To evaluate the accuracy and precision of various turn switch (TS) detection methodologies used in alpine skiing literature.
• To assess the influence of different sensor types on TS detection performance.
• To provide guidance for selecting the most appropriate TS detection method based on specific needs.

Main Methods:

• Replicated existing TS detection methodologies from scientific literature.
• Recorded data using optoelectronic motion capture, inertial measurement units (IMUs), pressure insoles, portable force plates, and electromyography (EMG).
• Used a validated optoelectronic motion capture method (Supej) as the reference standard for comparison.

Main Results:

• All analyzed TS methodologies demonstrated accuracy within 0.25 seconds, with ten achieving accuracy within 0.05 seconds.
• Precision varied across methods, ranging from approximately 0.10 to 0.60 seconds.
• The Klous Video, Spörri PI (pressure insoles), Martinez CTD (connected boot), and Yamagiwa IMU (inertial measurement unit) methods exhibited the highest performance in both accuracy and precision.

Conclusions:

• Several TS detection methodologies offer reliable accuracy and precision for alpine skiing analysis.
• The choice of TS detection method should consider the available sensor technology, desired performance metrics, and the specific application.
• Further research can refine TS detection techniques and sensor integration for enhanced biomechanical analysis in skiing.