Written By: ATH Director of Human Performance Frank Bourgeois, PhD and ATH Performance Coach Natalia Marthinson
INTRODUCTION
Jump ability is widely considered a favorable characteristic that underpins athletic performance [6]. Performance in jumping tasks has been shown to be largely correlated with performance in tasks such as linear sprinting [5], multidirectional sprinting [1], and quality of life [4]. As such, jump training is a common component of performance training when aiming to improve stretch-shortening cycle and neuromotor capabilities [3,6].
The primary purpose of this article is to provide a general understanding of some biological and mechanical factors that underpin jump performance. The second aim is to describe how these elements may be moderated to emphasis particular muscle-tendon qualities, and further challenge the motor system for well-rounded, safe and effective athletic development.
DISCUSSION
Key Biological Factors of Jump Performance
The three-component model is a classic representation of the biological makeup of the muscular system, specifically muscle-tendon units [2]. The three-component model consists of the Contractile Component (CC), the Series Elastic Component (SEC) and the Parallel Elastic Component (PEC) (Figure 1). Briefly, the CC predominantly pertains to actin and myosin filaments which form cross bridges to produce shortening and control lengthening at the level of the sarcomere. The SEC is largely represented by the tendon as its elastic properties allow the transmission of force to the bone. The PEC is another elastic component composed of connective tissue such as endomysium, perimysium and epimysium that lie adjacent to CC, and further augments generated force [2].
Figure 1. Illustration of the 3-component model. CC = contractile component, SEC = series elastic component, PEC = peripheral elastic component, F = force.
Key Mechanical Factors of Jump Performance
When developing a jump training program, it is also important to be mindful of a key factor that underpins performance - the technical application and utilization of generated force [8]. Moreover, the time factor associated with locomotion, and thus athletic maneuvers, further highlights the importance of impulse (i.e. forceΔtime), which more accurately describes the cumulative influence of force on a body’s momentum (i.e. massΔvelocity), and its influence on athletic performance. A training approach that focuses on impulse and technique (i.e. kinematics) not only prepares individuals for activities of daily living and competitive environments, it may also reduce injury risk.
Insight into the influence of force and jump ability can be found in the fact that force is a vector. By definition, a vector is a metric that quantifies magnitude and direction [7]. Relative to force, magnitude simply notes the amount of force exerted, while direction notes which way net force (i.e. summation of forces) is expressed in. These two quantities, coupled with an understanding of the three component model, can be used to categorize and prescribe jump modes according to intensity and direction to strategically progress individuals of all statuses in jump training in a safe and effective manner.
Approach to Jump Training
A continuum may be devised to categorize jumps that emphasize the biological components of CC, SEC and PEC. For instance, squat jumps may be categorized as CC-dominant tasks due to the diminished contribution of elastic energy that is lost as heat. Pogos and drop jumps may be categorized as SEC-dominant tasks due to the more shallow joint ranges that place higher demands on tendons as well as central and peripheral nervous systems. Lastly, countermovement jumps may be classified as CC- and PEC-dominant tasks due to the larger joint ranges that will rely on the physiological generation of force as well as the utilisation of elastic energy developed from mechanical strain placed on passive elements such as Titian and the connective tissues that surround myofibrils and muscle fascicles.
The continuum may also extend to the vector quantity of ground reaction force - that is, how intense a jump task is, and in what direction the jump will occur - and may be modulated by imposing specific constraints a jump task must be executed. First, the magnitude, or intensity, of a countermovement jump may be enhanced by progressing from a traditional countermovement jump to a tuck jump. Moreover, a unilateral tuck jump will further increase magnitude by the greater demand placed on a single leg. Second, the direction net force is applied and returned in will also impose different demands on the motor system. For instance, an accentuated jump can be progressed from a box drop jump that consists of a vertical descent to a double-leg anterior (i.e. forward) jump to a jump task that consists of a double-leg anterior jump that proceeds a single-leg contralateral jump.
PRACTICAL APPLICATION
At Athlete Training and Health there is a simple, yet effective approach that employs phases of introduction, emphasis and variety to its jump training. During the introduction phase individuals are exposed to the underlying training stimuli of the day’s focus. Next, the emphasis phase gives specific attention and time to the training objective, where the model of execute, teach execute is used to sharpen motor skills. Finally, the variety phase is where individuals are exposed to movement variability to further enhance movement competency and athletic performance.
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