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Proper jumping technique to mitigate lower leg injuries and optimize performance

 

 

 

         Jumping can be a big asset when we want to work power, stability, or cardio, especially if we are limited to only our body weight. There are many exercises that can be done to work these various purposes. Jumping is also directly correlated with our sprint speed, considering that jumping is also an explosive movement activating the same muscles, engaging the fast-twitch, type IIb fibers. However, we must be aware of the stresses that jumping places on the body.

         I often can attribute the metaphor of mountains to most things in my life and the simple act of jumping is no different. Successful mountain climbing doesn’t just mean having a successful ascent, but also having a safe descent. That requires knowing how to get down before going up - It is no different in a jump. When we jump, we must consider our landing before takeoff, otherwise we may not return to the ground safely. Before we can begin maximizing power, it is important to nail down a safe and efficient landing position. According to a study done in 2010, our landing mechanics play a vital role in the prevention of ligaments tears in the knee, specifically the ACL (Norcross, Blackburn, Goerger, and Padua). We refer to landing as the loading phase because it also serves the purpose of maximizing the subsequent jump. The foundation for optimizing power output is directly correlated to optimizing the loading phase. The technique of jumping has been derived from the understanding of biomechanics and through that understanding we have discovered the optimal angles of body positioning. Having large hip and knee flexion angles at the initial foot contact with the ground do not necessarily reduce the impact forces during the landing, but active hip and knee flexion do. Hip joint motion at the initial foot contact with the ground appears to be an important technical factor that affects anterior cruciate ligament loading during the landing (Yu, Lin, & Garrett). During landing, be sure to make contact with the ball of the foot first and gradually allow the pressure to melt through the foot until the heel softly touches the ground.  It’s like pressing the brake in your car. When you slam on the brake it creates a lot of stress on the car and the passengers of the car, whereas gradually coming to a stop doesn’t affect anything or anyone.

        When talking about the biomechanics of the jump, the spine also plays a vital role. The spine runs from your neck, which contains your cervical vertebrae, all the way to the coccyx, aka your tailbone. Keeping the entire spine in as straight of a line as possible will increase power, control, and safety. Looking at the ground naturally promotes a straight spine while in the hinge position.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

         As you drop back into optimal position, be aware of your hips going backwards and down, ultimately loading your posterior chain (glutes, hamstrings, and back), greatly reducing pressure on the knees and ankles. Maintain full control during the lowering phase, being sure not to go past the optimal angle at the hip, knee, and ankle. Everyone is going to vary in their range of motion, so be sure not to go past your optimal angles. The common indicator that you’ve surpassed your optimum hip angle is if your back begins to curve. The common indicator of proper position and knee angle is if you feel most of the pressure in your glutes and hamstrings. If you are in more of a squat position as opposed to a hinge position, then the pressure will be felt in the front of the thigh (quad) and knee. Again, remember it is the posterior chain that we are loading. The posterior chain is acting as a rubber band and as we optimize how well we load it we also optimize the subsequent power that is generated. Bring the arms back, parallel with the spine, and in unison with the hips lowering backward. Before rising up into the jump begin the motion of the arms, throwing them ahead of the hips, greatly increasing the power of the jump due to the momentum it creates for the hips. Upon landing, return to your optimal hinge position as gently and controlled as possible. If you are interested in how to create more strength, power, stability, and range of motion for this position read our article “Preventing injury and maximizing performance in the hinge position”. Below is the case study that sparked this article, as it proves that teaching proper landing mechanics can mitigate impact by over 20%.

 

 

         In 1999, the Journal of Sports Orthopedic Therapy published a study conducted by doctors Prapavessis and McNair. They were researching the effects of joint stress due to the impact of landing. They wanted to prove that if people knew the proper body positioning and joint angles they’d be able to reduce their impact. They taught one group proper mechanics and angles, while the other group simply got told to use the experience of the first rep to improve upon it. The result was incredible. The subjects that were taught how to properly land reduced their impact by over 20%. Even more exciting is that this study doesn’t take into account the location of the stress based on mechanics. This means the stress we reduce on our knee by being aware of proper form is much greater than 20%.

 

 

 

Study Design

Randomized, controlled trial.

Objective

To determine the roles that augmented feedback from instruction in jumping technique and sensory feedback from experience jumping play in assisting individuals to land softly from a jump.

Background

Jumping and landing activities play a major role in many sports and daily activities. Feedback may assist individuals in decreasing landing forces and thus reduce the chances of sustaining an injury.

Methods and Measures

Nonimpaired subjects (n = 91) were randomly assigned to either an augmented or sensory feedback condition. All subjects were asked to jump from a box 300 mm in height and land as softly as possible on a force plate. Pre-intervention ground reaction forces (GRF) were recorded. Subjects in the augmented feedback condition were then given instructions to focus on hip and knee joint motion as well as a forefoot landing technique for their next jump. Subjects in the sensory feedback condition were asked to use the experience of their first jump to land softly for their next jump. Post-intervention GRFs were recorded and all GRFs were expressed as a multiple of body weight.

Results

Those in the augmented condition significantly reduced their GRF scores from pre- (mean = 4.53 ± 1.51) to post- (mean = 3.57 ± 1.10) jump, whereas those in the sensory condition did not (mean pre GRF = 4.51 ± 1.77; mean post GRF = 4.33 ± 1.54).

Conclusions

High ground reaction forces may be a precipitating factor associated with an injury, where the site of tissue damage would benefit from decreased forces. These findings support the use of instructions related to joint motion to reduce landing forces.

J Orthop Sports Phys Ther 1999;29:352–356.

 

 

Nicholas S. Beauchamp, October 2019

 

 

 

 

Citations

 

Bing Yu, Cheng-Fing Lin, William E. Garrett (2006), “Lower extremity biomechanics during the landing of a stop-jump task” Clinical Biomechanics v.21, issue 3, March 2006, Pages 297-305

 

Marc F. Norcross, J. Troy Blackburn, Benjamin M. Goerger, Darin A. Padua (2010), “The association between lower extremity energy absorption and biomechanical factors related to anterior cruciate ligament injury” Clinical Biomechanics v.25, issue 10, December 2010, Pages 1031-1036