Abstract

The validity and reliability of the Optojump system were investigated for jumping height and flight time in vertical jump tests. Conversely, the purpose of the present study was to investigate the validity and reliability of the Optojump system for measuring contact time and lateral displacement in change of direction and lateral jump tests. Thirty basketball collegiate athletes were tested on two 10 m sprints with a 60° (COD60) or 180° (COD180) change of direction, lateral controlled (CLRJ) and maximal (MLRJ) rebound jump, and lateral countermovement (LCMJ) and squat (LSJ) jump with the concomitant use of two force plates and the Optojump system for the measurement of contact time in COD60, COD180, CLRJ, MLRJ, and lateral jumping distance in all the lateral jump tests. Almost perfect coefficients (r ≥ 0.95) emerged for contact time in COD60, COD180, CLRJ, MLRJ, although a systematic bias was found for COD60 (−0.01 s). Good-to-excellent reliability was found for almost all the measurements of contact time and lateral jumping distance for change of direction and lateral jump tests. Therefore, the use of Optojump system for testing change of direction and lateral jumping abilities should be executed with caution, avoiding misinterpretation of data.

Highlights

  • Change of direction and jumping abilities represent an expression of the reactive strength, which has been defined as “the ability to quickly switch from an eccentric contraction to a concentric contraction” [1]

  • Thirty basketball collegiate athletes were tested on two 10 m sprints with a 60◦ (COD60) or 180◦ (COD180) change of direction, lateral controlled (CLRJ) and maximal (MLRJ) rebound jump, and lateral countermovement (LCMJ) and squat (LSJ) jump with the concomitant use of two force plates and the Optojump system for the measurement of contact time in COD60, COD180, controlled lateral rebound jump (CLRJ), maximal lateral rebound jump (MLRJ), and lateral jumping distance in all the lateral jump tests

  • This study demonstrated for the first time that the Optojump system (OptojumpNext, Microgate) cannot provide a valid measurement of contact time for all the conditions tested, whilst it exhibited a “good” internal consistency reliability for the measurement of the contact time during change of direction and lateral jump tests

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Summary

Introduction

Change of direction and jumping abilities represent an expression of the reactive strength, which has been defined as “the ability to quickly switch from an eccentric contraction to a concentric contraction” [1]. The coupling of an eccentric and concentric contraction refers to the stretch-shortening cycle [2] Both change of direction and jumping abilities rely on the stretch-shortening cycle. Change of direction is a preplanned action and a critical performance determinant in many team sports. It refers to the ability to decelerate (i.e., eccentric component) in the shortest time and quickly re-accelerate (i.e., concentric component) in a new direction while running or sprinting [3,4,5]. The jumping ability can be exerted in a vertical, horizontal, or lateral direction or their combination. Considering that athletes could be tested using a laboratoryand/or a field-based approach, the most suitable and practical approach should be decided based on availability of instruments, time, space, and money

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