How to Launch a Human Rocket: The Jump-X

By Jason Avedesian, MS, CSCS, PhD Candidate @ UNLV Interdisciplinary Health Sciences (Biomechanics)

A previous blog addressed the importance of developing lower body strength and power for athletic performance and reducing the risk of injury.  Strength and conditioning coaches can utilize a variety of techniques such as barbell or dumbbell training, bodyweight exercises, resistance cords, or machine-based systems to train the lower body. While all of the aforementioned modalities have merit within a training program, certain factors may exclude athletes from performing certain exercises or using specific modalities. Training experience, injury history, and sporting season (in-season vs off-season) all play a role in determining the appropriate lower body training modality for developing strength and power.

In this post, I will discuss the Jump-X Machine by Perform-X Training Systems, a lower body training application that can be an excellent addition to any training environment. More specifically, the biomechanical differences between the Jump-X and traditional barbell training, as well as ways that a S&C coach can incorporate Jump-X with a training program will be discussed. Currently, the Jump-X Machine is utilized within several high school, collegiate and professional programs.

The Biomechanics of the Jump-X

The first thing to discuss with the Jump-X Machine is gravity. Gravity is the almighty force that imposes restraints on performance and elevates injury risk if one does not demonstrate movement proficiency in the upright gravitational plane. With the Jump-X’s horizontal sled, gravity is not acting directly on the athlete. This design may be ideal for athletes with recurrent back pain or spinal disc issues.

Here’s what the research says. During a half-squat with loads ranging from 0.8-1.6 times body weight, compressive forces on the L3-L4 spinal segments were 6-10 times an individual’s body weight (Cappozzo, 1985). Deviation from a neutral spine position (can be as little as 1-2 degrees of excessive lumbar flexion or extension) during the squat may also heighten the risk of disc injury (Schoenfeld, 2010).

The Jump-X’s unique design make it ideal for developing strength and power qualities for athletes of all skill levels. While the machine can be used for traditional leg presses, the 7-foot sled also allows for plyometric jump training. What you’ll also notice is that the sled and platform are not quite at a 90 degree angle to each other. This is ideal for plyometric training in that it helps reinforce a toe-heel landing during single and double-leg jump-landings. Compared to midfoot or rearfoot (although very rare) landings, a toe-heel landing reduces the external load on the lower extremity structures (Dufek, 1991).  Often, typical plyometric training (especially with an external load) emphasizes performance output at the expense of proper jump-landing mechanics.  With the Jump-X, specific performance qualities (e.g., stretch-shortening cycle, reactive strength index) can be enhanced in a safe manner.

A great introduction for athletes with low training age

Adolescent athletes with no prior exposure to strength training are another population at greater risk for back injury during traditional barbell squatting. How many videos have you seen posted on social media of high school athletes performing heavy barbell squats with cringeworthy form? Too many to count right? Well, the Jump-X can be a great introduction for athletes learning how to handle external loading for the first time. The padded platform provides a great tactile cue for the athlete to maintain a neutral spine position throughout the movement. The overhead handles provide greater stability compared to free weight exercises, reducing the risk of low back, hip, and knee injuries in younger or inexperienced lifters.

Variable resistance loading: Resisted and Assisted

An additional feature of the Jump-X is the ability to utilize accommodating resistance or variable resistance loading in both a resisted and assisted.  Variable resistance can help train athletes through “sticking points” within a pressing movement or allow for additional external loading during jump-landing exercises.  Using it in an assisted manner can also help develop safe practices during the landing phase of plyometric training and also during the rehabilitation of injured athletes.

Inclusion of the Jump-X Machine within a Strength & Conditioning Program

The Jump-X Machine can be a great addition to a comprehensive strength & conditioning program to build robust athletes or rehab injured athletes of all ages.  Relative to the traditional barbell squat, the Jump-X Machine offers an easy-to-introduce exercise to an athlete with a low training age.  The barbell squat and / or deadlift can be very technical and time-consuming to teach within a training session, and “over coaching” an athlete on these exercises can lead to frustration and ultimately disinterest.  With the Jump-X Machine, a few simple cues such as “feet shoulder width apart”, “back flat on the sled”, and “drive through the midfoot” are easy for the athlete to understand and complete.  Plus, it begins to establish the squatting movement pattern so that transition to the barbell squat is easier.

Most, if not all, strength and conditioning coaches strive for every athlete to be proficient with barbell training.  However, circumstance is key here and not every athlete is ready or suited for this type of training.  The Jump-X is a great segue way to barbell-type training for younger or inexperienced athletes and can be used as a transitional training tool during rehabilitation from a major lower body or back injury.

Conclusion

The Jump-X Machine offers the ability to develop lower body strength and power in safe and effective ways that traditional exercises cannot.  Whether your program tailors to high school, collegiate or professional athletes, the Jump-X Machine is a valuable tool.

References

Cappozzo, A., Felici, F., Figura, F., & Gazzani, F. (1985). Lumbar spine loading during half-squat exercises. Medicine & Science in Sports & Exercise,17(5), 613-620. doi:10.1249/00005768-198510000-00016

Dufek, J. S., & Bates, B. T. (1991). Biomechanical Factors Associated with Injury During Landing in Jump Sports. Sports Medicine,12(5), 326-337. doi:10.2165/00007256-199112050-00005

Schoenfeld, B. J. (2010). Squatting Kinematics and Kinetics and Their Application to Exercise Performance. Journal of Strength and Conditioning Research,24(12), 3497-3506. doi:10.1519/jsc.0b013e3181bac2d7