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Principles of program design: agility training

This is an excerpt from Preventing Noncontact ACL Injuries eBook by Human Kinetics.

Agility may be considered one of the primary movement skills needed for successful participation in multidirectional sports and an important component of training programs aimed at reducing risk for injury. Previous successful injury prevention programs have all incorporated sport-specific agility into their programs to some level. Agility represents the ultimate in neuromuscular control because it is a product of the coordination between the musculoskeletal and neural systems for interpretation of sensory information and integration of that information into task-appropriate motor output (Schmidt and Lee 1999). Agility can be characterized by the ability to maintain postural stability in conditions that require changes in speed and direction in response to the environmental demands. Tasks that require agility constitute a specialized form of coordination for athletes that when trained properly results in improved athletic performance and reduced risk for injury. Because agility requires motor skill development that incorporates a combination of strength, power, and balance, you will see that agility training overlaps or combines all of these training modalities.

Motor skills required for agility can be categorized as continuous, discrete, and serial. Continuous motor skills are those in which the movement is cyclical and repetitive, with an arbitrary beginning and end. In contrast, discrete motor skills represent a distinct, manipulative-type skill that has a specific beginning and end. Lastly, serial motor skills represent a combination of continuous and discrete motor skills (Magill 1989). Within each of these categories a hierarchy from general to specific to specialized exists. This hierarchy involves increasing complexity due to changes in factors such as the plane of movement, the coordination of joints, and the introduction of environmental obstacles.

General continuous motor skills include tasks such as walking, running, and hopping, typically performed in a forward direction. Specific continuous motor skills are more complex because they involve a different direction or plane of movement (e.g., backward run or lateral shuffle) or a change in the coordination of segments for movement (e.g., increased hip flexion or knee flexion for high knees and heelers). Finally, a progression to specialized continuous motor skills involves a level of complexity that requires a combination of specific continuous motor skills in the context of a sport-specific goal (see table 5.1 for examples of continuous locomotor skills). For example, specialized continuous motor skills may require the athlete to move through several planes of movement at varying speeds while interacting with another player or responding to an unanticipated cue.

Table 5.1 Examples of Continuous Locomotor Skills
General (developmental)	Specific (athletic)	Specialized (sport)
Walk	Acceleration skip	Tempo: jog to sprint
Run	Carioca	Speed: straight-ahead sprint
Gallop	Shuffles (lateral galloping)	Agility combinations: • backpedal to sprint • sprint to backpedal • slides to sprint
Skip	Slides	Performing set patterns or plays
Jump	Heelers	Creating patterns or combinations: • proactive/evading/offensive
Hop	High knees	Responding patterns or combinations: • reactive/evading/defensive
Leap	Backpedal
	Backward run
	Lateral crossover
	Crossover skip

Unlike continuous motor skills, discrete motor skills are not repetitive but involve a specific task. General discrete skills are those needed to perform tasks aimed at the development of strength and power (e.g., lunge and jump). Specific discrete skills are more complex and involve factors such as speed modulation and change of the plane of direction (e.g., stop jump or direct cut). The final progression of discrete skills is accomplished by introducing a sport-specific implement while performing the specific skill (e.g., basketball layup or volleyball hit). As you can see, discrete skills often represent the transitions between continuous skills (see table 5.2 for examples of discrete motor skills). For example, the side-step cutting maneuver transitions between two directions of running and is the progression of a receive (catch and collect) task. We can train these transitions in the context of a discrete movement because mastery of these skills with particular attention to technique is important for injury prevention.

Table 5.2 Examples of Discrete Motor Skills
General (developmental)	Specific (athletic)	Specialized (sport)
Squat	Ready stance	Offensive vs. defensive lineman stance
Lunge	Jump stop	Infielder vs. outfielder stance
Jump: land/propulsion	Throw a ball	Serve receive
Hop: land/propulsion	Hit a ball	Point guard vs. post defensive stance
Leap: land/propulsion	Direct cut (sidestep cut or power cut)	Layup for basketball vs. volleyball hit
Receive: catch, collect	Indirect cut (crossover cut)	Softball vs. baseball infielder throw
Kick	Kick a ball	Tennis serve 1 vs. 2
Pivot	Stutter step	Tennis backhand with or without slice
Swing	Hesitate	Soccer: kick, pass, shot
Punch
Statics: balance, support
Weight transfer: balance
Turn
Twist
Stretch/extend
Curl/flex

Serial motor skills represent a combination of continuous and discrete skills that are common in multidirectional sports such as soccer and basketball. The sequencing of continuous and discrete skills is highly related to sport-specific agility. For example, Bledsoe (1996) reported basketball players will change movement type or direction approximately every 2 s with combinations of sprinting, backpedaling, shuffling, jumping, hesitating, accelerating, and walking—with and without the basketball—equating to approximately 1,000 different movements per game. Additionally, these athletes sequence multiple combinations of continuous and discrete skills. Training a progression from general to specialized motor tasks within continuous and discrete skills should be tailored to meet the needs of the athlete for the sport and position.

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