Effect of Low-Pass Filtering on Isometric Midthigh Pull Kinetics

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• Force-time characteristics are crucial in assessing athletic performance.
• Data processing techniques, like low-pass filtering, can influence kinetic measurements.
• Standardization of filtering methods is essential for reliable longitudinal analysis.

Purpose of the Study:

• To evaluate the impact of low-pass filtering (LPF) on isometric midthigh pull (IMTP) kinetics.
• To compare unfiltered (UF) data with LPF data at cutoff frequencies of 10 Hz (LPF10) and 100 Hz (LPF100).
• To determine the acceptability of filtering-induced differences in IMTP force-time variables.

Main Methods:

• Analysis of 40 IMTP trials from 24 collegiate athletes.
• Comparison of kinetic data (body weight, onset threshold force, time-specific forces, peak force) between UF and LPF (10 Hz and 100 Hz) conditions.
• Statistical analysis using p-values, effect sizes (g), percentage differences, and limits of agreement (LOA).

Main Results:

• LPF significantly reduced onset threshold force compared to UF (p < 0.001).
• LPF10 led to unacceptable underestimations of time-specific forces compared to UF.
• LPF100 and UF showed acceptable differences for time-specific forces and peak force (PF).
• No significant differences were found for body weight between filtering conditions.

Conclusions:

• Low-pass filtering can lead to underestimation of IMTP kinetics.
• LPF at 100 Hz provides acceptable agreement with UF data for most kinetic variables.
• LPF at 10 Hz yields unacceptable differences, particularly for onset threshold and time-specific forces.
• Standardizing filtering procedures or using unfiltered data is recommended for accurate IMTP force-time analysis.