Preparatory Body State before Reacting to an Opponent: Short-Term Joint Torque Fluctuation in Real-Time Competitive Sports

Abstract

In a competitive sport, the outcome of a game is determined by an athlete’s relationship with an unpredictable and uncontrolled opponent. We have previously analyzed the preparatory state of ground reaction forces (GRFs) dividing non-weighted and weighted states (i.e., vertical GRFs below and above 120% of body weight, respectively) in a competitive ballgame task and demonstrated that the non-weighted state prevented delay of the defensive step and promoted successful guarding. However, the associated kinetics of lower extremity joints during a competitive sports task remains unknown. The present study aims to investigate the kinetic characteristics of a real-time competitive sport before movement initiation. As a first kinetic study on a competitive sport, we initially compared the successful defensive kinetics with a relatively stable preparatory state and the choice-reaction sidestep as a control movement. Then, we investigated the kinetic cause of the outcome in a 1-on-1 dribble in terms of the preparatory states according to our previous study. The results demonstrated that in successful defensive motions in the non-weighted state guarding trial, the times required for the generation of hip abduction and three extension torques for the hip, knee, and ankle joints were significantly shortened compared with the choice-reaction sidestep, and hip abduction and hip extension torques were produced almost simultaneously. The sport-specific movement kinetics emerges only in a more-realistic interactive experimental setting. A comparison of the outcomes in the 1-on-1 dribble and preparatory GRF states showed that, in the non-weighted state, the defenders guarded successfully in 68.0% of the trials, and the defender’s initiation time was earlier than that in the weighted state (39.1%). In terms of kinetics, the root mean squares of the derivative of hip abduction and three extension torques in the non-weighted state were smaller than those in the weighted state, irrespective of the outcome. These results indicate that the preparatory body state as explained by short-term joint torque fluctuations before the defensive step would help explain the performance in competitive sports, and will give insights into understanding human adaptive behavior in unpredicted and uncontrolled environments.

Enhancing High-Intensity Actions During a Basketball Game After a Strength Training Program With Random Recovery Times Between Sets

“…Despite this finding, more studies are needed to more thoroughly understand this relationship. A previous study investigated the kinetic cause of the outcome in a 1-on-1 dribble situation in terms of the defensive player (14). The findings showed that the defender's mediolateral peak trunk acceleration was higher in situations involving offensive players, irrespective of the outcome (successful or unsuccessful defensive motions) compared with light-emitting diode equipment situation (14).…”

Influence of Augmented Probabilistic Information on Defensive Motor Behaviors of 1 vs. 1 Basketball Play

“…The defender’s initiation of leg flexion relative to ball movement, as induced by the attacker, was taken as the temporal reference for analyzing the defender’s other motor reactions. The rationale for selecting this event in time was based on the fact that movements of lower extremity joints have been previously used to indicate preparatory states during real-time competitive performance (e.g., kinetics of hip, knee, and ankle contribute to outcomes in a 1-on-1 dribble basketball; see Fuji et al., 2015).…”

An ecological dynamics approach to ACL injury risk research: a current opinion

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