Brault et al. (5) commented that the most significant angular changes were found in the upper trunk, because attackers exaggerated shoulder movement in the opposite direction to where they will run. Additionally, it was hypothesized that by exaggerating upper-body movements, the defender's attention would be taken away from the pelvic region that offers more abundant information in terms of anticipating the future running direction.
In a follow-up study by Brault et al. (6), the researchers found that when anticipating the direction of an attacking player's step, novice players were more focused on deceptive signals (e.g., upper-trunk yaw) in contrast to the expert performers who were more attuned to “honest” (COM) signals. It was concluded that the expert performers were extracting relevant information from the honest signals. As a result, they made fewer errors than the novice group and were able to use these signals to successfully guide their actions to intercept the attacking player (6).
APPLYING BIOMECHANICS TO AGILITY TRAINING
The potential use of biomechanical research as a tool to enhance the anticipation ability, and in turn sport-specific reactive ability for athletes, is very valuable for coaches. Previously, coaches have been limited to use opposed drills, including shadow drills, mirror drills, 1-v-1 drills, etc., coupled with footwork technique drills to train for the reactive element of performance (7). By using biomechanical analyses of opposition players, coaches can now assess what specific cues are available that can indicate what the defender is likely to do next. This information can therefore be used as a coaching instruction for their players. Specifically, using this knowledge as an instruction when conducting sport-specific open agility drills may enhance the quality of the information pick-up by the learner. Examples of drills that can be used in tandem with biomechanical feedback are shown in Figure 2.
When using biomechanical instruction within feedback for their athletes, coaches should instruct their athletes to focus on the “honest” signals being displayed by the opponent as opposed to the “deceptive” signals. Research has shown that expert performers are more attuned to information pick-up from these types of signals as opposed to novice athletes who are more focused on the “deceptive signals” (6). The honest signals (e.g., COM displacement, lower-trunk yaw) displayed by attacking opponents are necessary actions required to change the direction, which makes manipulation of such variables much harder for the player without disrupting their movement pattern. Deceptive signals (e.g., head yaw, upper-trunk yaw), which have no influence on movement production, are more easily manipulated by the opponent and thus can lead to incorrect decisions by the athlete if this is the sole source of anticipatory information pick-up.
Coaches should be viewing their athletes as they perform these agility drills to provide feedback, which can include biomechanical instruction, and thus help their athletes to more successfully respond in the correct way to an opponent's actions. For example, if an athlete is particularly susceptible to being eliminated (i.e., taken out of the defensive play) when the attacking player displays deceptive movements, the coach should instruct the defending athlete to focus their attention on the hips of the attacker rather than more distal variables such as head and upper-body movement. Coaches can use drills to instruct athletes on which cues hold abundant information on cutting direction (COM displacement, lower-trunk yaw) and which cues are used as deceptive signals (head/upper-trunk yaw, out-foot displacement). Examples of coaching feedback that can be used in these types of structured activities are provided in Table 2.
Coaching cues will revolve around getting the defending player to focus on maintaining good athletic position as described by Dawes and Roozen (7) (e.g., head slightly forward of hips, maintain a flat back with neutral lumbar spine, knees slightly flexed, weight on balls of feet, hips, and shoulders square to opponent, feet slightly more than shoulder width apart), so they can respond rapidly and make changes of direction in response to their opponent. In addition to these cues, the defending player needs to focus their vision on the attacking player's hips and avoid being deceived by upper-body trunk and head yaw movements intended to get them in a weak defensive posture.
For the defender in a drill, such as that described in Figure 2B, the objective is to remain square to the attacker for as long as possible while moving backward up the channel and responding with short, rapid powerful movements that mirror those of their opponent (the attacker). The coach should instruct the defender to avoid turning their hips too early or getting caught flat-footed with their stance too wide as they respond to the attacker; these postures make the defender vulnerable to the attacker either stepping back on their inside (if the defender turns their hips too early) or to being beaten with pace as the attacker runs around (or inside) them when caught flat-footed and with a wide defensive stance.
Using biomechanical analyses to increase anticipatory ability in athletes is specific to a wide range of sports including rugby union, rugby league, Australian Rules football, American football, basketball, and tennis. Most of the sports that require participants to respond to an external stimulus, resulting in a rapid change of direction, would benefit from biomechanical analyses being performed on the common deceptive movement patterns performed by opponents. Such information would allow coaches to provide their athletes with feedback that would help to improve their movement effectiveness to the deceptive movement patterns of a given opponent.
Until this point, athletes have generally developed perceptual-cognitive abilities through being exposed to sport-specific scenarios over a lengthy period. By instructing athletes from an early age on what specific cues to look for from an opponent's body orientation, the learning time for improving reactive ability through movement anticipation may be substantially reduced.
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Keywords:© 2014 by the National Strength & Conditioning Association
rugby football; deceptive movement; anticipation; agility