The Load-Velocity Slope Is an Indicator of the Active Drag in all Competitive Swimming Strokes

Tomohiro Gonjo*, Maria Vitazka, Ingeborg Ljødal, Bjørn Harald Olstad

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Introduction
Active drag in swimming is a critical variable that affects swimmers' performance as well as the physiological load, but it is challenging for practitioners to assess this variable. This study aimed to assess if the load-velocity profiling method can be used as an indicator of active drag.

Methods
A total of 419 swimmers performed three semi-tethered swimming trials in their speciality among the four competitive strokes with different external loads. Linear regression between external load and swimming velocity, as well as the external load relative to the body mass and swimming velocity, were established. The active drag and drag coefficient of each swimmer were calculated using a velocity perturbation method.

Results
There were significant correlations of the active drag with the absolute slope (r ≥ 0.713, p < 0.001) and relative slope (r ≥ 0.538, p < 0.001) in all four strokes and both sexes. A multiple regression analysis exhibited that the primary determinant of these relationships was the drag coefficient (semi-partial correlation ≥0.404, p < 0.001). The effects of the height and body mass index (BMI) on the relationship between the drag and the absolute slope were small (0.195 ≤ semi-partial correlation ≤0.248, p < 0.001) in both cases, which became either non-significant (height: p ≥ 0.282) or trivial (BMI: -0.099 ≤ semi-partial correlation ≤ -0.073, p ≤ 0.009).

Conclusions
These results indicate that the absolute load-velocity slope is a strong indicator of the active drag, and the relative slope is useful when indirectly assessing the drag coefficient.
Original languageEnglish
JournalMedicine and Science in Sports and Exercise
Early online date16 Sept 2024
DOIs
Publication statusE-pub ahead of print - 16 Sept 2024

Keywords

  • ABSOLUTE LOAD
  • DRAG COEFFICIENT
  • HYDRODYNAMICS
  • RELATIVE LOAD
  • RESISTIVE FORCE

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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