Why Use Moving Stimuli for Agility Training
What is Agility?
For most, agility involves executing preplanned movements (e.g., a quick acceleration to the left or a jump to the right) developed through hours of repetition in practice. The athlete knows (or is told by the coach) what movement they will make before the training activity starts (e.g., go left when you get to the first cone). But there is something critical missing from this conceptualization of agility– its purpose! Agility involves making functional or purposeful movements that achieve some goal – getting around a defender in soccer, avoiding a tackler in football, or getting to the correct location at the net to block an attack in volleyball. This requires that the movements are driven by information that the athlete picks up from their environment, telling them whether a cut to the left or the right will achieve their goal. Research has shown that the movements athletes make are completely different in terms of the body angles and positions used and ground reaction forces generated when preplanned versus when coupled (linked to) some information they pick up from their environment (1). This is why agility was recently redefined as “a rapid whole-body movement with change of velocity or direction in response to a stimulus (2).”
“Agility is a rapid whole-body movement with change of velocity or direction in response to a stimulus”
Agility Training With Static Stimuli: The Old Approach
In an attempt to train agility under this new definition, coaches typically use non-informative static (non-moving) stimuli: a light turning on telling a player where to move, an auditory beep that tells the athlete when to change direction, etc. While this does make training more unplanned and unpredictable (making it better than traditional preplanned movements), these stimuli are non-informative because they do not contain information that naturally tells the athlete which direction to go to achieve their goal. There is no reason to go left or right around a cone – that must be assigned by the coach. This is, of course, entirely unlike what happens in the game – a soccer or basketball player dribbling a ball will cut to the left because the defender is leaning to the right. We have removed the purpose from the way we train agility!
Agility Training With Moving Stimuli: A New Approach
SwitchedOn’s new Moving Ball stimuli directly address this limitation. As first discussed by James Gibson (3), moving stimuli contain specifying (specific to) information that can be used to control our actions. For example, as an object moves toward us, the image size it creates on our eye expands. The rate at which its image size is expanding is specific to one and only one event in the world, e.g., a value of 2 means the object will reach us in 2 seconds, no matter what the shape, speed, or distance of the object. Conversely, an object moving away from us (receding) creates a pattern of contracting motion on our eye, with the rate of contraction indicating how quickly it is moving away. Thus, object expansion or contraction is natural information that we can use to control our actions. The images below illustrate research that has demonstrated this with animals.
Images from research on animal responses to moving/looming stimuli (McKee, et al. 2020) (Franceschi, et al. 2016)
Using a sports example, imagine that you are defending an opponent 1:1 in an invasion sport like basketball or soccer. You don’t want to get too close so the opponent can easily cut around you or too far away so that they have room to shoot. How can we achieve this? When we want to regulate the distance between ourselves and another object in our environment, this can easily be achieved by coupling our movement with the type of motion information we have been discussing (5). When the opponent’s image contracts, we move towards the opponent. When it expands, we move away. This is the exact situation being trained in the first 10 seconds of the example training video below.
Example training video using the SwitchedOn app's Moving Ball stimuli.
Tap this link while on your mobile device to try this drill!
In this 1:1 defending situation we also need to keep our body between the opponent and our goal. This can again be easily achieved by establishing a coupling between our movements and laterally moving information. As also illustrated in the example training video, if the opponent’s image moves right, we move right. If it moves left, we move left. Not surprisingly, research has shown that we seem to have specialized detectors in our brains for this useful type of motion information (4,5), and this information is what is used to perform a wide range of sporting actions, from playing 1:1 defense (6) to other skills like spiking a volleyball (7), catching or hitting a baseball (8), and saving a ball in soccer (9).
Training agility using moving stimuli like this also has another distinct advantage. We can train the control of action (e.g., change of direction, acceleration) and decision-making (i.e., when to use the action) at the same time! When we use static stimuli to train agility, we must train the skill twice. Think about practicing cutting left or right by running around cones. Ok, the athlete can now perform these cutting actions successfully. But we are still left with the problem of training the athlete’s ability to decide when to use them in a game! These new agility training stimuli developed by SwitchedOn create opportunities for athletes to develop the functional connection between their movements and (some of the same) information sources that they will use to achieve their goals in the game. Instead of planning to go left or right beforehand, the athlete learns to pick up information that informs them about this – just like they will need to do in a game. They develop the ability to execute agility movements and the ability to decide when to use them at the same time!
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1. Mercado-Palomino, E., Richards, J., Molina-Molina, A., Benítez, J. M., & Espa, A. U. (2020). Can kinematic and kinetic differences between planned and unplanned volleyball block jump-landings be associated with injury risk factors?. Gait & posture, 79, 71-79.
2. Sheppard, J. M., & Young, W. B. (2006). Agility literature review: classifications, training and testing. Journal of sports sciences, 24(9), 919–932.
3. Gibson, J. J. (1966). The Senses Considered as Perceptual Systems. Boston, MA: Houghton Mifflin.
4. Billington, J., Wilkie, R. M., Field, D. T., & Wann, J. P. (2011). Neural processing of imminent collision in humans. Proceedings of the Royal Society B: Biological Sciences, 278(1711), 1476-1481.
5. Sanada, T. M., & DeAngelis, G. C. (2014). Neural representation of motion-in-depth in area MT. Journal of Neuroscience, 34(47), 15508-15521.
6. Nagano, T., Kato, T., & Fukuda, T. (2004). Visual search strategies of soccer players in one-on-one defensive situations on the field. Perceptual and motor skills, 99(3), 968-974.
7. Lee, D. N., & Young, D. S. (1985). Visual timing of interceptive action. In Brain mechanisms and spatial vision (pp. 1-30). Dordrecht: Springer Netherlands.
8. Gray, R.(2021). Invited review: Approaches to visual-motor control in baseball batting. Optometry & Vision Science, 98, 738-749.
9. Craig, C. M., Goulon, C., Berton, E., Rao, G., Fernandez, L., & Bootsma, R. J. (2009). Optic variables used to judge future ball arrival position in expert and novice soccer players. Attention, Perception, & Psychophysics, 71, 515-522.