02 Nov Return To Plyometric Exercises In 4 Steps
This article will feature a 4-step progression in developing the stretch-shortening cycle which is crucial for returning to plyometric exercises. The stretch-shortening cycle is an active eccentric stretch (lengthening of a muscle) followed by an immediate concentric contraction (shortening of a muscle). This is similar to a spring; you first stretch the spring to create potential energy, then it is released into active energy. The stretch-shortening cycle is often used in plyometric training and is crucial in every sports training program. The 4-steps in the progression include eccentric jumping, low-intensity fast plyometrics, hurdle jumping, and depth jumping. This 4-step progression will help athletes safely develop the stretch-shortening cycle that is essential for every sport that involves jumping or change of direction activities, such as basketball and volleyball.
The importance of going through these steps is that it helps create stiffness in the lower extremity. This stiffness that we refer to is best described as the resistance to the deformation of an object in response to an applied force. This resistance is the complex interactions of muscle tendons, ligaments, cartilage, and bone. This stiffness has been known to influence performance in hopping, jumping, running and with the change of direction. An athlete who has greater stiffness will store more elastic energy during the phase of ground contact and generate more concentric force output at push-off increasing running speed and jump height. This easy 4 step progression helps the athlete to safely return to jumping and eventually lead to plyometric training.
Step 1: Eccentric Jumping
The first step in developing the stretch-shortening cycle is by performing an eccentric jump. In this phase, we must teach the athlete the correct landing mechanics and how to stick the landing. We often preach to an athlete that you must have good brakes in a fast car or else it is a recipe for disaster. Furthermore, the majority of non-contact injuries occur during the deceleration phase of activities, such as landing and cutting.
The ultimate goal of these exercises is to improve the athlete’s ability to withstand the downward velocity and eccentric load of plyometric activities. Withstanding the eccentric load of plyometric exercises is crucial in developing the stretch-shortening cycle. The biggest cue that we give our athletes is to land softly, which will allow them to actively absorb the shock. Also, we have the athlete “freeze” to observe if there are any faults with their landing mechanics, such as dynamic knee valgus (femoral adduction/internal rotation) or lack of knee/hip/trunk flexion. In the video below we show variations of eccentric jumping. Prior to having the athlete land from a box, we teach them how to perform snap downs with a medicine ball to simulate landing from a box in order to teach proper landing mechanics. Once they demonstrate the proper technique with the snap down, they should be progressed to landing from a box.
- Land as softly as you can
- Freeze at the bottom/Stick the landing
- Bend at the hips, knees, and trunk
- Don’t let your knee cave in
Looking to master landing mechanics? This article will give you a break down of what you should be looking for when first introducing landing to yourself, your clients, or your patients.
Step 2: Low-Intensity Fast Plyometric Exercises
In this phase, the main goal is to introduce the spring and release concept of the stretch-shortening cycle. The goal of this fast plyometric exercise is to reduce ground contact time. In other words, the leg should act like a spring and rebound with minimum delay off the ground. A coaching cue we like to use is to tell the athlete to imagine that the ground is a hot surface and the goal is to get off the floor as quickly as possible. The athlete should aim to stay on the balls of their feet; this will allow the athlete to pre-activate the lower leg muscles before landing allowing them to enable the “stiff-spring” response. In the video below we demonstrate three exercises: double leg ankle hops, single leg ankle hops, and skipping to use as low intensity fast plyometric exercises.
- Imagine that the ground is a hot surface
- Get off the floor as quick as possible
- Stay on the balls of your feet
- Minimize knee bending as you land
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Step 3: Hurdle Jumping
Once the athlete has understood the concept of the fast plyometric jump, they are progressed to hurdle jumping; hurdle jumping is a continuation of the prior phase. The goal is the same in minimizing ground contact time; however, we are introducing height as a parameter in this phase. Once the athlete is able to clear at least four hurdles with minimal ground contact time, the height of the hurdle may be increased to produce an overload effect. In the video below we show hurdle jumping with both single leg and double leg jumping.
- Imagine the ground is a hot surface
- Stay on the balls of your feet
- Fixed jump height across all hurdles
Is jumper’s knee limiting you from getting back to jumping? Check out this article on how to recover from jumper’s knee.
Step 4: Depth Jumping
In this last step, we focus on depth jumping. The main goal of this phase is minimizing ground contact time and maximizing jump height. The depth jump is a great exercise that will help develop that; however, most of the time the athletes are progressed to this exercise without going through the necessary progressions to get to this. In the depth jump, we can measure the Reactive Strength Index or RSI. The RSI measures the athlete’s ability to change quickly from an eccentric (load acceptance) to concentric contraction (convert passive to active energy; loaded spring analogy).
This can be seen as the athlete’s “explosiveness”. Explosiveness has been used to describe an athlete’s ability to develop maximal force in minimal time. In the NBA, people often say how Zion Williamson is so explosive, it is because of his ability to work at a fast rate, Power=Work/Time. The goal for every athlete is to have a ground contact time around .25 seconds, which research has shown to be the gold standard of a fast short stretch cycle. That time is the measurement between your feet touching and leaving the ground. In the video below we show variations of a depth jump with both and single legs. The box should be between 8-16 inches. The progression of these exercises is to increase the box height if the athlete is able to achieve .25 seconds for ground contact time.
- Jump fast, Jump high
- Imagine the ground is a hot surface
Try this 4-step progression for your athletes when you are introducing them to plyometrics!
AUTHORS: THE BASKETBALL DOCTORS
- Brazier J, et al. Lower extremity stiffness: Considerations for testing, performance enhancement, and injury risk. Journal of Strength and Conditioning Research 2019
- Flanagan, E and Comyns T. The use of contact time and the reactive strength index to optimize fast stretch shortening cycle training. 2019