Trahan, A., Vicknair, H. & Page, P. (2024)
Background: The “Deceleration Index” (DI) theory is based on the assumption that deceleration forces and speed should be at least equivalent to acceleration forces and speeds. An increased efficiency in the ability of an athlete to decelerate or “break” during a change in direction of movement may be associated with improved performance and lowered risk of injury. Purpose: The purpose of this pilot study is to develop the methods to quantify the DI during change-of-direction (COD) via the “5-10-5” sprint test using the 1080 Sprint device (1080Motion, Sweden). Study design: This original research was a pilot of an observational cohort study (Level 3). Material & Methods: Moderately active, healthy adults were eligible for this pilot study that were tested indoor on gym surface with regular athletic shoes. Subjects were attached to the 1080 device cable at the waist and performed a 5 yard "assisted" sprint, reversed direction, and performed a 10 yard "resisted" sprint, and reversed direction for a final 5 yard "assisted" sprint with a 2 kg resistance was set in the 1080. Subjects chose their pivot leg and five trials were completed by each participant. Data were sampled at 333Hz with the raw data of the middle 3 repetitions used. The peak velocity of each of the 3 phases was determined. Points of interest at 50% of peak velocity were identified during the 2 changes of direction (turns). The DI ratios of velocity and acceleration were determined from points, Results: 10 subjects participated. The average DI for COD 1 and COD 2 for deceleration/acceleration were 1.43 ± .44 and 1.66 ± .95, respectively. The DIs for speed were .86 ± .09 and .87± .7 at COD 1 and COD 2, respectively. The coefficients of variation were generally high for COD 2 in speed and acceleration, and for COD 1 during acceleration (.81, .57, and.31). Conclusion: Quantifying the DI may help improve athletic performance or identify parameters for return to sport. These methods should be repeated in a larger athletic population.