FIGURES FROM THE WIMBLEDON FINALS 2019 (OFFICIAL WIMBLEDON YOUTUBE CHANNEL)
SPEED OF REACTION vs SPEED OF RESPONSE
The efficiency of the preparation step in tennis, referred to as a split step, is usually considered from the aspect of the muscle activation and the timing of movement itself. We consider that the efficiency of the preparation step relies on players’ abilities of visual detection and extraction of the meaning out of environmental and kinetic cues when creating a response.
One of the key performance objectives in tennis is efficient adaptation to the changing playing conditions. Efficiency of the adaption should be determined by receiver’s response competency made up of the pre-motor reaction time (RT) and a movement time.
The pre-motor reaction time is minimum time required by the nervous system to process information from the sensory systems and initiate a motor action (Nijhawan, 2002). Shorter the processing time, faster a movement response can be initiated.
As the motor time differs very little among the healthy individuals and physically prepared professional athletes (McMorris, 2009), processing of information from the environment (context and opponents’ movement) could be a key differentiator for successful and superior performance in sports and even classification of athletes as experts. One key component of the pre-motor reaction is the optic-motor integration having the usage of the visual system, as dominant sensory system, critical for successful interceptive actions in guiding an appropriate motor response. Pre-motor time response is a pointer of how efficiently (timely and accurately) an individual can process necessary information and create interceptive action. Interceptive actions are the outcome of perceptual information identification, decision of aresponse selection, and an appropriate motor response initiation. How players perceive stimuli from the context and its dynamics (opponent’s stroke affordances or limitations) can determine an outcome of the action in which they are engaged preceding a decision of of the final movement response initiation.
Therefore, a superior performance in pre-motor reactions is based on a combination of most efficient usage of the visual search strategies, perceptual abilities, and cognitive selection processes. Stimuli perception and its cognitive recognition affects player’s reaction and response time, influencing the dynamics of the movement. The perceptual evaluation of the sources of potential information is the foundation of the decision-making process based on which players can create early action potentials.
Therefore, we observe split step from the standpoint of three neuromuscular sequential action phases:
1. Effective information processing (visual scene search and detecting the most relevant action dependent information),
2. Response selection corresponding opponent’s action and context (geometrical positions of the players at the court)
3. Timely motor response initiation
And phases in which these neuromuscular action sequences are executed:
- Pre-split step Momentum phase (Anticipation and Momentum of the split step)
- Split step Air phase (Gathering information and producing goal-directed action decision)
- Split step Landing phase (Motor response and its accuracy)
- PRE-SPLIT STEP MOMENTUM PHASE
NEUROLOGICAL ASPECT OF SPLIT STEP – perception/anticipation of the context
Player’s performance in tennis is influenced by detection of as many relevant information as possible to speed up the reaction and initiate movement response earlier.
Contextual information is related to the characteristics of the current context and how would potentially changes in the context influence the game dynamics. These changes could be individualized and specific for the opponent and his/her technical -tactical preferences (Vernon G, Farrow D and Reid M (2018) or situation specific determined by the opponents’ movement momentum in relation to the movement momentum of the ball.
As tennis game is based on the interaction between the players and the ball, receiver’s response depends on the observations of the opponent’s stroke intentions and dynamic point specific sources of information. By creating awareness of preferable strokes and zones of placement, strengths, and weaknesses in technical and physical capabilities, receivers can predict the action preferences and make early decisions of the corresponding momentum and timing of the split step.
Tennis players have own timing mechanism determined by the perception of the game context and detection of the opponent’s movement, stroke, or ball flight (Filipcic et al., 2017). Timing of the take-off in the split step depends on the anticipated stroke intentions (pace and direction of the incoming ball) at the pre-contact phase or due to the later observed ball trajectory at the post-contact phase. Depending on the perception of the context and dynamics of the point, split step sequence momentum could be directed sideways, forwards, or backwards, as a predictive movement. Faster split-step execution depends on the better reaction, but on the specificity of game situations (contextual anticipation) as well (Filipcic et al. (2017). Experts tend to move towards the optimal position at the court for receiving the ball before their opponent sets up for the stroke. While hitter moving towards the future zone of impact, expert receivers usually engage their perceptual-cognitive abilities to predict the potentials of the incoming ball. They are trying to predict the potential direction and intensity of the incoming ball based on the affordances or limitations in creation of the stroke momentum by the hitter. Based on these point specific sources of information, they decide of the optimal receiving position and movement momentum (direction forwards, backwards or lateral). In this way, split step landing response can be used more efficiently with receiver being closer to the potential incoming ball direction (FIGURE 1).
We observed how players create their movement momentum towards the optimal split step position at the court determined by the context and dynamics of the point. By predicting stroke probability (FIGURE 1) based on the opponent’s future impact zone and potential of the stroke momentum, a receiver (Federer) creates pre-split step momentum (IMAGE 1, green arrow) with consecutive split step hops in lateral direction (IMAGE 2, green dotted circle, pre-contact). We can think of these movements as predictive since the intention is the movement towards the optimal receiving position before the hitter’s impact and based on the information about the hitter’s stroke intentions (IMAGE 1, yellow arrow). Final split step position (IMAGE 3, green dotted circle) just at the time of the hitter’s impact initiates the final movement momentum to the incoming direction of the ball (IMAGE 4, PRONATION, green circle).
By detecting the limitations (lack of possible forward momentum) (FIGURE 2) as Federer is transitioning towards the impact zone, receiver (Djokovic, green square) initiates earliest accurate predictive movement response. Djokovic did not initiate his split step movement closer to the middle of the court but between the middle line and sideline. This strongly suggests his intention of positioning for the cross-court stroke, excluding the possibility of the down the line stroke from his opponent.
Anticipatory movement can be identified as every movement momentum initiated before the racquet-ball contact, initiated before the receiver even had a chance to make a decision based on the incoming ball direction. By observing reactions and movement of the opponents towards their impact zone, players tend to weight the possibilities or limitations that the dynamics of the situation is placing on the opponent, to predict their stroke affordances or limitations.