Improving Jump Performance with Vector Concepts: Identifying Trainable Deficits

Jumping is a ballistic action that involves quickly accelerating the body off the ground and then decelerating it upon landing. The angle at which this is done dictates the direction of the jump and, consequently, the performance outcome.

The goal is usually to jump higher, farther, or faster. Acceleration vectors can help us quantify (and subsequently train) jumping patterns more effectively to improve performance.

“the challenge that sports practitioners face is figuring out whether the root cause of performance deficits is poor technique or underlying muscle weakness”

For some athletes, especially novices, jump performance can be improved by improving technique. Various instructional cues have been shown to improve jump performance outcomes quickly but may produce only moderate or no improvements in more experienced athletes. Understanding why an athlete cannot perform a desired jump technique as intensity increases and/or fatigue accumulates during gameplay is vital in determining if muscle-specific performance deficits are to blame.

We will take a look at the acceleration vectors involved in vertical and horizontal jumping and what kind of interventions can be used to train technique and muscle factors.

Training Interventions for Vertical Jumping

In vertical jumping, propulsive accelerations should exist only in the vertical direction through the body’s center of mass (COM).

Technique factors.

Various research studies have found that external cueing can be a powerful motor learning tactic to improve force output, postural stability, and movement automaticity. This has been attributed to better quadriceps recruitment and more effective force application onto the ground, which together enhance both the magnitude and the direction of take-off accelerations and upward jump trajectories (Gokeler et al 2013; Markwell et al 2023; Raisbeck and Yamada 2019). However, it’s important to note that the chosen cue can greatly influence its effectiveness.

Technique cue example:

“push the world down” instead of “extend your ankle, knee, and hip”

Muscle factors.

In the image below, we can see how both the external loading demands and work requirements will differ based on how the hip, and knee joints are positioned relative to the body’s center of mass (COM).

Our movement strategies (i.e., technique) will determine the loading requirements for the knee and hip extensors. We can visualize this with external moment arms - the horizontal distance between the COM and each joint.

The ability of the knee extensors (i.e., quadriceps) to release as much energy as possible and maximally accelerate the body upwards is a major determinant of vertical jump height.

In order to maximize the upward acceleration, the feet need to remain under the body’s COM. If this doesn’t happen, accelerations will occur at an angle, and the max jump height achieved will be less than if all knee extensor effort was used vertically. To do this, the knees must be able to travel forward over the toes and require considerable knee extensor strength and ankle dorsiflexion range of motion.

How the jumper applies force to the ground will impact the take-off acceleration vector direction and, in turn, the max jump height and distance achieved.

Interestingly, although concentric ankle plantar flexion range of motion during the vertical jump propulsive phase has been shown to be significantly correlated to max height performance, ankle flexibility training does not improve heights achieved (Hall et al 2010; Panoutsakopoulos et al 2022; Papaiakovou et al 2006). Instead, these ankle range of motion correlations reflect the necessity of the knee extensors to produce large propulsive forces in a more challenging, forward knee position to initiate vertical acceleration. In the case of poor ankle flexibility, multi-joint exercises that target the knee extensors in this forward knee position will be more effective than just stretching the ankle plantar flexors (Baker 1996; Bobbert and van Zandwijk 1994; Bobbert and van Soest 1994; Bryanton et al 2012; Chiu et al 2017; Fry et al 2003).

Performing a lunge with an upright torso and forward knee position will effectively increase external loading demands of the knee extensors for training vertical propulsion.

Training Interventions for Horizontal Jumping

Horizontal jumping necessitates an increasing horizontal component for the take-off acceleration.

Technique factors.

Horizontal jumping is challenging for many novice athletes due to the increased postural stability demands. In preparation for take-off, limb segments must rotate forward to shift the body’s COM forward, increasing the accelerations in the horizontal direction and optimizing take-off trajectory. This also means that the COM must shift toward the boundaries of our base of support (i.e., shift toward postural extremes). External cues are also helpful for improving horizontal propulsion capabilities in novice athletes (Becker and Smith 2015; Ducharme et al 2016; Porter et al 2010; Porter et al 2012).

Optimizing horizontal jump distance requires optimizing the angle at take-off.

Technique cue example:

“try to jump to the visible distance target” instead of “jump as far as you can”

Muscle factors.

Horizontal propulsion is highly reliant on hip extensor performance capabilities, to extend and drive the hips forward via forceful contractions of the glutes, hamstrings, and adductor magnus (posterior head). The ankle plantar flexors play an important role in postural stability maintenance and effective acceleration off the ground. Considering this, the exercise interventions chosen to target the hip extensors and ankle plantar flexors should replicate these loading and positional requirements (Bryanton et al 2012; Fry et al 2003; Vigotsky and Bryanton 2016).

A conventional deadlift is an effective resistance training exercise for horizontal propulsion due to its large hip extensor moment requirements.

Applications in Sport

Sports that involve repetitive propulsive actions (like blocking shots or tackling) require athletes to be able to optimize their jump trajectories and the specific muscle contributions, and maintain them over an entire session/game. As fatigue begins to set in, a player’s jump trajectory may change, which can reflect the different fatigue patterns of the different muscles and allow you to focus training strategies on the areas that need it most.

Example 1: Basketball

Fatigue of the quadriceps can cause unintended increases in horizontal displacement during a jump shot due to compensatory movement strategies that shift loading demands to the hip extensors.

In basketball, the vertical component is more dominant during jumping.

Example 2: Football

Offensive linemen need a large amount of strength, agility, and balance to create momentum quickly. If they show progressive increases in their vertical take-off accelerations without also showing increases in horizontal acceleration, they are likely losing efficiency in their tackles. In this case, their training programs should be adjusted to emphasize the hip extensor.

During a football tackle, we can see an increasing need to generate propulsion in the horizontal component.

Take Action

Using vectors as a tool, we can identify the necessary movement and loading requirements to maximize sport-specific propulsive patterns and choose appropriate training interventions when there are shortcomings. Many sports involve maximal, repetitive, or exhaustive actions, causing the accumulation of fatigue. Vector principles can help us reveal WHY movement patterns cannot be sustained, where the performance deficits lie, and highlight the most effective interventions to improve an athlete's propulsive capacity for the unique demands of their sport.