Effect of low-pass filtering on isometric midthigh pull kinetics

Dos'Santos, T; Lake, J; Jones, PA; Comfort, P

Abstract

The purpose of this study was to investigate the effect of low-pass filtering on isometric mid-thigh pull (IMTP) kinetics, including body weight (BW), onset threshold force, time-specific force values (50, 100, 150 and 200 ms) and peak force (PF). Forty IMTP trials from twenty-four collegiate athletes (age: 21.2 ± 1.8 years, height: 1.72 ± 0.09 m, mass: 79.4 ± 8.2 kg) were analyzed and compared using unfiltered (UF) and low-pass filtered (LPF) (Fourth-order Butterworth) with cut-off frequencies of 10 (LPF10) and 100 (LPF100) Hz. Significantly lower (p < 0.001, g =-0.43 to- 0.99) onset threshold forces were produced when force data were LPF. This led to significant (p < 0.001, g = 0.05-0.21) underestimations of time-specific force values when LPF10 compared to UF, displaying unacceptable percentage differences (1.2-3.3%) and unacceptable limits of agreement (LOA) (-25.4 to 100.3 N). Although significantly different (p ≤ 0.049), trivial (g ≤ 0.04) and acceptable percentage differences (≤0.8%) and acceptable LOA (-28.0 to 46.2 N) in time-specific force values were observed between UF and LPF100. Statistically significant (p < 0.001), yet trivial (g ≤ 0.03), and acceptable percentage differences (≤0.7%) and acceptable LOA (-4.7 to 33.9 N) were demonstrated in PF between filtering conditions. No significant differences (p = 1.000) and identical BW values were observed between filtering conditions. Low-pass filtering results in underestimations in IMTP kinetics; however, these differences are acceptable between LPF100 and UF, but unacceptable between LPF10 and UF (excluding PF). Filtering procedures should be standardized when longitudinally monitoring changes in IMTP force-time characteristics to allow valid comparisons; with analysis of UF data recommended.

Citation

Dos'Santos, T., Lake, J., Jones, P., & Comfort, P. (2018). Effect of low-pass filtering on isometric midthigh pull kinetics. Journal of Strength and Conditioning Research, 32(4), 983-989. https://doi.org/10.1519/JSC.0000000000002473

• Journal Article Type: Article
• Online Publication Date: Jan 29, 2018
• Publication Date: Jan 29, 2018
• Deposit Date: Mar 5, 2018
• Publicly Available Date: Nov 15, 2019
• Journal: Journal of Strength and Conditioning Research
• Print ISSN: 1064-8011
• Publisher: Lippincott, Williams & Wilkins
• Volume: 32
• Issue: 4
• Pages: 983-989
• DOI: https://doi.org/10.1519/JSC.0000000000002473
• Publisher URL: http://dx.doi.org/10.1519/JSC.0000000000002473
• Related Public URLs: https://journals.lww.com/nsca-jscr/pages/default.aspx