INTRODUCTION
Strength and conditioning coaches spend a significant amount of their time developing training programs, with the intention that such practice will transfer to enhance athlete performance. After performing a needs analysis for athletes, careful consideration is given to the loads used, volume, frequency, timing, and type of progressions to make appropriate gains in hypertrophy, strength, power, and endurance. However, it is suggested here that developing an athlete's perceptual-cognitive skill (the ability to identify and acquire environmental information for integration with existing knowledge such that appropriate responses can be selected and executed (15)) rarely undergoes the same amount of planning and consideration. Although drills are typically designed to challenge athletes to read and respond to sport-specific cues, programming progressions are more difficult to prescribe and quantify.
AGILITY
The definition of agility among researchers and implementation by coaches in the field has been undergoing transformation. In early literature, agility was defined simply as “the ability of the body or body parts to change directions rapidly and accurately” (2). These earlier definitions only described the physical aspects of agility with the testing and training protocols used by coaches often reflecting such definitions. Typically, agility testing often saw the use of simple movement drills with preplanned changes of direction (COD) and included tests such as the “t –test” (4), “Illinois Agility Run,” “505-test” (8), and the L-run (16) as a way of assessing agility. Similarly, training drills have used variations of these preplanned tests, in addition to footwork technique drills, as a means of improving agility.
More recently, researchers have noted that the ability to efficiently read and respond to stimuli within the environment can differentiate elite and sub-elite performers (9,11,12). This has seen the inclusion of open drills into the strength and conditioning programming of coaches. These drills challenge the athlete to move in response to sport-specific stimuli in the presence of spatial and temporal uncertainty. Because most sports do not involve preplanned movements, these open-type drills have strong appeal with the potential for greater transfer to the performance setting.
ANTICIPATION
The ability to anticipate an opponent's intentions has been highlighted as being of paramount importance within the performance context (1,10,11). In many sports, the time constraints placed on the performer necessitate the need for an athlete to anticipate an opponent's actions based on partial or advance sources of information (1). For example, a tennis player needs to gather information from observing the server's body orientation to get a “head-start” on moving in the correct direction, because waiting for the ball to be struck does not offer enough time to return the ball effectively (10). Rugby league players benefit greatly by having the ability to read advanced cues from the body orientation of an opponent (11). This ability enables the athlete to anticipate future movement direction earlier, which in turn provides a greater amount of time to formulate a response that allows the athlete to put oneself in a position to make an effective tackle. Players who cannot read these early cues have to wait until the opponent initiates a change of direction, at which point it may be too late to make a successful play. The importance of training for game-specific decision making was highlighted in recent work assessing the effects of feints on agility performance in Australian Rules football players (13). The research showed that the speed and accuracy of a defender's agility performance was hindered when the attacking players used a feint in their attacking movements rather than a non-feint movement. This was accentuated in lesser-skilled players, highlighting the need for game-specific anticipation and decision-making training (13).
TRAINING ANTICIPATION USING BIOMECHANICAL RESEARCH
Most research involving biomechanics within the field of strength and conditioning has, by and large, focused on deciphering the most efficient technique in which to perform a certain task. Biomechanical analyses have been used to determine the most efficient technique within a range of activities including Olympic-style weightlifting (3), resistance training (17), and sprinting (14). However, recent research using biomechanical analyses has unlocked a potential benefit for training an athlete's ability to anticipate and move in response to a stimulus. Brault et al. (5) studied the biomechanics of attacking players who were trying to eliminate a defender during a 1-v-1 rugby situation. Through the use of a motion analysis system, the researchers performed a biomechanical analysis to determine what postural information could be used to predict the future running direction and what movements were used by the attacker in an attempt to “wrong-foot” the defender. The results showed that during deceptive movements, attacking players exhibited a strategy involving 2 processes: (a) the use of false (deceptive) parameters to mislead the defender into thinking the attacker will run in the opposite direction, and (b) the minimization of other parameters (honest) to keep the postural stability flexible so that the attacker can still change their final running direction (5). The study showed that the attackers minimized both their center of mass (COM) displacement and lower-trunk yaw during deceptive movements. In addition, out-foot displacement, head yaw, and upper-trunk yaw were all exaggerated during deceptive movements (5). Table 1 and Figure 1 provide definitions and examples of these postural signals and movements.
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Table 1: Deceptive/honest signals used by attacking players in rugby according to Brault et al. (5)
Figure 1: Example of an athlete performing deceptive (head and upper-trunk yaw) movement before intended change of direction. (A) Initial upper-trunk and head yaw in opposite direction to intended path. (B) Out-foot displacement with full upper-trunk and head yaw. (C) Center of mass displacement, knee flexion, and rapid reversal of the upper-trunk and head yaw as change of direction is initiated. (D) Rotation of the lower trunk as the athlete drives off outside foot in the desired direction. (E) Change of direction complete.
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.
Figure 2: Drills that can be used in tandem with biomechanical feedback. (Panel A) An attacking athlete (A), holding a rugby ball, starts at one end of the 10-m × 8-m playing area, directly opposite to a defensive player (D). On the coach's command, both athletes move toward each other with the attacking player's goal to reach the other end of the playing area by making a cutting maneuver and eliminating the defender. The defending athlete's goal is to make a 2-handed tag on the attacking player's torso. After each repetition, the players can return to the opposite end of the drill, therefore alternating between serving as the attacker and defender. (Panel B) Both the attacker (A) and the defender (D) start at the same end of the grid with the defender 1.5 m in front of the attacker (facing each other with the defender's back to the grid). The attacker, in possession of a rugby ball, moves forward and makes small changes of direction in an attempt to “wrong-foot” the defender. The defender's goal is to stay directly in front of the attacker and maintain the 1.5-m gap by moving backward at the same speed as the attacker is advancing. The attacker's goal is to deceive the defender and make a cutting maneuver which eliminates (wrong foots) the defender. The drill concludes when the attacking player eliminates the defender or both players exit the grid. (Panel C) Both an attacker (A) and a defender (D) start next to each other, outside the playing grid. On the coach's command, both players sprint to their end of the grid. At this point, the drill becomes an elimination drill with the attacking player's goal to reach the other end of the playing area by making a cutting maneuver and eliminating the defender. The defending athlete's goal is to make a 2-handed tag on the attacking player's torso. After each repetition, the players can return to the opposite end of the drill, therefore alternating between serving as the attacker and defender. The width and length of the grid can be altered to make the drill more challenging for the defender. The attacking player performs the drill in possession of a rugby ball.
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.
Table 2: Examples of coaching feedback specific to opposed agility drills
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.
PRACTICAL APPLICATIONS
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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