24 Mar Principles and Guidelines of Speed, Acceleration, and Agility
An athlete’s ability to outrun the opposing team is a characteristic of many athletic endeavors. As is the ability to change direction rapidly and beat an opponent during competition. A common component of field sports is high speed locomotion and rapid changes of direction. Additionally, many track and field events success is based upon linear locomotion and rapid acceleration. It is these characteristics of sport which make addressing speed, agility, and change of direction an integral component of training the athletic population.
Speed
Speed can be defined as the skills and abilities needed to achieve high movement velocities (Haff and Triplett, 2016). The process by which speed is developed within the athletic population is a combination of physiological components developed through a structured program. During the development of speed acknowledging high-speed locomotion can typically be categorized as either linear or multidirectional is important (Haff and Triplett, 2016). Linear speed, often referred to as sprinting is the underlying component of many track and field events and open field aspects of team sports. The multi-directional components of team sports are equally important in the acquisition of speed. The reason to acknowledge this characteristic of directional change relative to speed necessitates the athlete having the ability to accelerate and reach maximal velocity (Haff and Triplett, 2016). These components of speed require both technical and physiological proficiencies.
Acceleration
Acceleration is the ability to increase maximum velocity in a minimum amount of time (Bompan and Buzzichelli, 2019). As a result, acceleration is the main driver of determining speed performance over a short distance. For example, in field sports such as soccer or football where directional changes occur and speed is required, the ability to accelerate in the initial phases of sprinting is integral in successful play. The acceleration component of speed is linked to the physiological development of maximum strength, power, and technical aspects of the skill (Bompa and Buzzichelli, 2019).
Acceleration being based upon the variables of velocity and time, these two variables describing force relative to time available to produce force are rate of force development and impulse (Haff and Triplett, 2016). Rate of force development (RFD) is the development of maximum force in minimal time (Haff and Triplett, 2016). Impulse is the product of the generated force and the time required for this production (Haff and Triplett, 2016). Rate of force development and impulse can be physically represented on the force-velocity curve. The force-velocity curve depicts the inverse relationship between force and velocity (Clark and Lucent, 2010).
Force is represented on the y-axis whereas velocity is presented on the x-axis of this graph. Understanding of the force-velocity curve and inverse relationship associated with these two variables is integral in the development of acceleration, speed, and the corresponding exercise selection of these two components. The practical application of the inverse relationship between force and velocity for the purpose of acceleration would be applying forces at a greater rate (Haff and Triplett, 2016).
Understanding this component is integral as errors in programming can be made when the goal of applying forces at a greater rate for the purposes of acceleration and speed. For example, resistance training only for maximum strength may lead to improvements in force production, though at the same time such programming can reduce muscle contractile velocity. As a result, it is very important to address rate of force development and impulse with a well-rounded approach of programming eliciting physiological improvements on both the y-axis and x-axis of the force-velocity curve. This is achieved not only with resistance training but with other exercise modes such as plyometrics and over-speed training.
Physiological Components of Speed
Speed development is based upon physiological and performance factors. To understand how best to increase speed outputs, awareness on the underlying physiological components associated with speed and correlating acceleration is of great importance. Acknowledgment of the energy systems, muscular, and neural components are underlying directives for appropriate programming.
Acceleration and sprinting is a repetitive cycle involving high rates of force development, requiring the body to supply energy for the purpose of this repetitive forceful action. Sprinting involves a rapid release of energy allowing for a high rate of cross-bridge cycling to occur within this physiological activity (Bompa and Buzzichelli, 2019). The phosphagen, glycolytic, and oxidative system contribute energy supply for physical activity, though the phosphagen and glycolytic systems are predominant in most sprinting activities (Bompa and Buzzichelli, 2019). Contribution by the oxidative system would be dictated by the length, duration, number of sprints, and corresponding rest intervals (Bompa and Buzzichelli, 2019).
Recognizing the predominate energy systems associated with acceleration and sprinting are the phosphagen and glycolytic systems, physiological development should be centered upon the utilization of these two energy systems. Furthermore, the enzymatic alterations stimulated by actual sprint training can play an integral role in facilitating rapid muscular contractions by allowing for a faster of ATP supply from the glycolytic system (Bompa and Buzzichelli, 2019). This would dictate adaptations to multiple bouts of high intensity sprint intervals produces a beneficial training stimulus for the development of speed. (Bompra and Buzzichelli, 2019). Thus, dictating programming should include training beyond traditional resistance training.
The characteristics of muscle fibers in addition to adaptations to neural system can play a significant role in high velocity movements. Muscle fiber type appears to play a role in sprint performance (Bompa and Buzzichelli, 2019). Higher percentage of Type IIb fibers are advantageous for activities requiring high outputs of power (Bompa and Buzzichelli, 2019). Recognizing this connection and invariably the requirements of high-power outputs for acceleration and sprinting, programming eliciting the recruitment of the type II fiber types would be advantageous for the development of speed. Additionally, prolonged endurance training usually induces a shift from type II to a type I fiber composition (Bompa and Buzzichelli, 2019). This type of training would be counterproductive to the development of speed and as a result should be avoided in speed development. Knowing Type II fiber composition is required for the high-power outputs associated with acceleration and speed. Programming recruiting type II fibers including resistance training at the appropriate intensity, plyometrics, and explosive activities would be beneficial for the development of speed. Due to high speeds associated with speed development and sprinting, programming should emphasize exercises shown to increase neural drive while overloading the musculature of the hip and knee involved in the stretch-shortening cycle (Haff and Triplett, 2016).
Outside of fiber type composition, the neural factors play a role in the development of speed. High velocity activities such as sprinting requires a high level of neural activation (Haff and Triplett, 2016). The neural factors associated with speed include the sequencing of muscle activation, the stretch reflex, and neural fatigue (Bompa and Buzzichelli, 2019).
The stretch reflex also known as the myotic reflex is defined as the contraction of a muscle in response to a stretch (Bompa and Buzzichelli, 2019). Research supports the stretch reflex appearing to enhance force production when an athlete is sprinting (Bompa and Buzzichelli, 2019). Implementation of programming, exercises, and sprint training would appear to enhance the stretch reflex, thus improving force production during the sprinting action.
An additional neural associated component affecting sprint performance and speed development appears to be neural fatigue. Neural fatigue is defined as the involuntary reduction of voluntary activation within the nervous system (Miller et al.,2020). The fatigue appears to be a by-product of high intensity build up to a point where the CNS impulses necessary to contract the muscle fibers are handicapped (Mille et al., 2020). This overall reduction in CNS activity and reduced force output could impair sprinting and the acquisition of speed.
A review of the force-velocity curve and physiological components associated with sprinting and speed development would indicate a multi-faceted approach to training is required. This multi-faceted approach would address the force-velocity curve to improve force production and rate of force production. Increases in force production can be achieved with traditional resistance training where maximum strength is developed with the appropriate load and training intensity. Though such training does not necessarily address the rate of force production which appears to be an integral part of speed development. In order to increase the velocity at which force is produced, training must move on the y-axis of the force-velocity curve where impulse or rate is the central focus of the programming.
Additionally, considering the muscle fiber types associated with speed development, programing addressing type II fibers should be the primary focus of programming. Resistance training at the appropriate load and intensity can benefit the development of type II fiber composition associated with speed development. At the same time the high speeds associated with speed development and sprinting supported by the muscular system require attention. Exercises increasing neural drive with an overloading of the musculature system are needed and not all resistance training exercises can meet this requirement. The implementation of programming enhancing the stretch-shortening cycle such as plyometric drills where neural drive and movement velocity is high will be beneficial to a speed program.
Outside of muscle fiber type, considerable attention is needed in addressing the neural system. As research indicates improvement of the stretch reflex and reduction in neural fatigue will benefit sprint performance and should be a component of speed programming. Neural fatigue and the stretch reflex specific to the biomechanics of sprinting can not necessarily be addressed with resistance training and would require sprint training and additional modalities to elicit training-induced adaptations to muscle spindle activity and acute neural fatigue (Bompa and Buzzichelli, 2019).
Sprinting Technique
Aside from the physiological components associated with speed development, a technical aspect is associated with sprinting. The sprinting action is composed of two distinct phases. These two phases are a non-support (or flight phase) phase and support phase (Bompa and Buzzichelli, 2019). The nonsupport phase contains recovery and ground preparation, where as the support phase includes the landing (eccentric breaking) and concentric propulsion phase (Bompa and Buzzichelli, 2019). The action of sprinting is comprised of an alternating sequence of non-support and support phases.
Two components associated with these phases and speed is stride rate and stride length. Stride length can be defined as the distance covered with each stride (Clark and Lucent, 2010). Whereas stride rate is the number of strides take in a given amount of time or distance (Clark and Lucent, 2010). If stride rate increases, the amount of time spent in the support phase decreases while time spent on the flight phase increases, resulting in an increase in running speed (Hoffman, 2019). Additionally, if stride length increases and stride rate remains constant, running speed will increase (Hoffman, 2019). Understanding the phases of sprinting, stride rate, and stride frequency indicates speed improvement should emphasize not only the physiological components associated speed development, but also the biomechanical constructs associated with sprint technique (Haff and Triplett, 2019).
The technical aspects associated with the biomechanics of sprinting are composed of a series of subtasks which can be divided into three distinct phases: the start phase, acceleration phase, and top speed (Haff and Triplett, 2019). Physiological components are associated with all the biomechanical constructs and phases of sprinting, though additional technical aspects exist. Technical errors can result in the misapplication of forces in the sprinting action thus reducing overall speed (Haff and Triplett, 2019). The goal on the technical side of sprinting is teaching and promotion of the ability to properly transmit forces into the ground to optimize the athlete’s gait cycle (Haff and Triplett, 2019).
Technical training will focus upon eradicating inefficient movement patterns deterring from efficient sprinting mechanics. Such training will utilize drills and coaching cues to assist the athlete in improving postural positioning, kinetic chain sequencing, and proper transmission of forces into the ground. The biomechanical constructs and technical aspects of sprinting are not directly associated with resistance training and require a different programming template for proper implementation.
Agility and Change of Direction
Many field and team court sports require the athletes to make predetermined changes of direction in addition to reactionary changes of direction. These predetermined and reactionary components are multi-directional whereas sprinting is typically only linear in terms of locomotion (Haff and Triplett, 2016). The generation of high speeds in a linear plane of motion is classified as sprinting, whereas the multi-directional component of sport involves speed in a manner involving the deceleration, a change of direction, and a re-acceleration towards maximum velocity can be defined as agility (Haff and Triplett, 2016).
The underlying constructs associated with the development of speed such as rate of force development and impulse are applicable to the development of agility, though additional components require attention. Recognizing agility requires a deceleration and change of direction prior to re-acceleration, the braking of the kinetic chain needs to be addressed. In the case of acceleration, propulsion force is performed concentrically, while during the deceleration force is expressed eccentrically (Bompa and Buzzichelli, 2019). The latter requires more force since the athlete must overcome inertia (Bompa and Buzzichelli, 2019). Knowing this component associated with agility, programming must address this aspect which is not necessarily a concern of linear speed development.
As stated, the general skills and concepts such as rate of force production, improvement in impulse, and the technical skills learned during linear speed apply to agility and changes of direction, though additional components must be addressed. These additional components key to agility training are body control and awareness, recognition and reaction, starting and first step, acceleration, footwork, change of direction, and braking (Clark and Lucent, 2010). This aforementioned list involves the development of motor skills and can therefore be trained (Clark and Lucent, 2010). As a result of these skills being highly integrated during competition, these components are often trained simultaneously during agility and change of direction drills (Clark and Lucent, 2010).
In addition to the motor skill development required for agility, the additional factor of perceptual-cognitive abilities in relation to the demands of sport are needed (Haff and Triplett, 2016). In both field and court sports, a substantial number of preplanned changes of direction occur during competition. Though in addition, scenarios exist during competition where changes of direction must occur in response to an external stimuli within a tactical situation (Haff and Triplett, 2016). This reactionary component of agility requires attention and elicits focus during program design. This can be achieved through improving the perceptual-cognitive abilities which include visual scanning, anticipation, pattern recognition, situational awareness, and reaction time (Haff and Triplett, 2016). Many of these perceptual-cognitive abilities are sport specific and thus necessitate agility training to be specific to the demands of the sport (Clark and Lucent, 2010). Considering the sport specific aspect of these cognitive abilities, program design can incorporate these considerations into the agility programming within a periodization schedule for the sport.
It is apparent variances exist in relation to the development of agility as opposed to linear speed. As stated, the underlying constructs associated with speed development such as rate of force production, impulse, and associated neural aspects are transferable to the development of agility. Though additional motor skill development is needed in relation to the deceleration, change of direction, and re-acceleration components of the kinetic chain associated with agility. Additional attention is required in addressing the sport specific perceptual-cognitive abilities of agility. As a result, certain components for the development of speed and agility can be shared. Though additional programming is needed when the demands of the sport go beyond linear locomotion and speed.
Limitations Associated with Speed and Agility Programming
A structured periodization schedule for the athlete specific to the competitive schedule of their sport will incorporate programming to address the speed, agility, and change of direction requirements of their sport. This programming as stated will address the underlying physiological requirements of these athletic attributes moving beyond traditional resistance training in terms of the force-velocity curve. Additionally, this programming will address the technical aspects of speed development and added requirements of agility training from both a physiological and tactical perspective.
Not withstanding limitations do exists relative to improvements associated with speed and agility programing. Recognizing the muscle type associated with high levels of force outputs are type II fiber composition. As stated, properly implemented training can create some transition of fiber composition from Type I to Type II (Haff and Triplett, 2016). Though a predetermination exists in terms of an individual’s muscle fiber type based upon genetic make-up (Bompa and Buzzichelli, 2019). This genetic predetermination will directly affect an athlete’s abilities from a physiological perspective in terms of constructs associated with the development of speed and agility. These constructs would include power and force in relation to fiber type percentages of the athlete (Bompa and Buzzichelli, 2019).
Outside of fiber type make-up additional programming components not specific to a speed and agility program required attention for optimal improvement in these athletic constructs. These physiological constructs are centered upon joint mobility, soft tissue flexibility, segmental stabilization, and one’s balance capacities (Clark and Lucent, 2010). These additional physiological components are directly related to improvement in one’s speed outputs and increases in agility though may not be directly associated with speed and agility programming (Clark and Lucent, 2010). As a result, these additional physiological components require attention within the overall programming and periodization schedule.
Conclusion
A speed and agility program dedicated to addressing the sport specific needs of the athlete can improve these physiological outputs relative the athlete’s sport of choice. The training associated with these segments of programming go beyond traditional resistance training, even though resistance trainning does address some of the physiological components associated with speed and agility. In addition, it is important to keep in mind the additional physiological and cognitive components associated with agility training. Finally, a speed and agility program does have limitations associated with genetic predeterminations of fiber type and additional programming is needed to address physiological constructs associated with these training segments.
References
Bompa, T. Buzzichelli, C. (2019) Periodization theory and methodology of training 6th edition. Champaign, IL: Human Kinetics.
Clark, M. Lucent, S. (2010) NASM essentials of sports performance, Baltimore, MD: Lippincott Williams & Wilkins.
Haff, G. Triplett, N. (2016) Essentials of strength and conditioning 4th edition, Champaign, IL: Human Kinetics.
Hoffman, J. (2019) Physiological aspects of training and performance, Champaign, IL: Human Kinetics
Miller, J. Lippman, J. Trevino, M. Herda, T. (2020) Neural drive is greater for a high-intensity contraction than for moderate-intensity contractions performed to fatigue. Journal of Strength and Conditioning. 34 (11) 3013-3021.