How to Progress Plyometrics in the Later Stages of ACL Rehab

Previously, we set the stage for plyometric programming by discussing a case study. Joe is a male high school basketball player who tore his ACL while coming down from a layup. We have initiated plyometric training and Joe has demonstrated proficiency with landing mechanics and non-countermovement jumps. As we continue to progress plyometric training, we will continue to follow our three guiding principles.

First, we will progress Joe from stable (double limb) to less stable (single limb). Second, we will progress from low force to high force. We can accomplish this by progressing from a non-countermovement initiation to a countermovement initiation. Third, we want to progress from general to specific. We have initiated plyometric training with sagittal plane, vertical movements. Now, we will start to introduce more planes of motion in order to provide Joe with an environment that is similar to the one he can expect to encounter when he returns to the basketball court.


Progressing from Low to High Force


So far, we have established how to initiate plyometric training by teaching landing mechanics and non-countermovement jumps. Essentially what we have done is break plyometrics down into its two respective phases – absorption and propulsion. Next, we will begin to blend these phases together and teach our athlete how to utilize the stretch-shortening cycle (SSC).


In sport, the quicker an athlete is able to produce force – also known as rate of force development – the greater competitive advantage that athlete may have. Studies have shown that individuals who train plyometrics have the ability to produce force more quickly than those who perform heavy resistance training alone (Newton and Kraemer, 1994). Why is this? A major contributor to this training effect is the SSC. In fact, movements utilizing the SSC have been shown to increase performance by as much as 10-15% compared to movements without an SSC component (Turner and Jeffreys, 2010)


Characterized by a rapid muscle lengthening followed immediately by a rapid muscle shortening, the SSC utilizes the stretch reflex and stored elastic energy to optimize force potentiation. Try this. Place your hand flat on a table and actively lift your index finger off of the table. Now rapidly press your index finger into the table. Repeat this same exercise, but this time, passively stretch your index finger into extension prior to rapidly pressing it into the table. When the finger is stretched just prior to muscle contraction we are able to produce more force at a faster rate. This is the SSC at work and the same concept can be applied to plyometric training.


Below is a video that illustrates how we can progress from low force to high force plyometrics. After our athlete has demonstrated proficiency with non-countermovement jumps, we initiate countermovement jumps. Countermovement jumps utilize the SSC during takeoff for increased force production. We can start by performing a countermovement box jump, to decrease absorption forces during the landing phase, before progressing toward a countermovement vertical jump. Next, we perform drop jumps. With drop jumps, we step off of a box before performing a vertical jump. The goal with drop jumps is to minimize ground contact time, similar to a pogo jump. Drop jumps are progressed to depth jumps. These are performed in a similar fashion to drop jumps, except this time we increase ground contact during the loading phase for increased force production during takeoff. Finally, we progress to multiple response vertical jumps. This progression forces the athlete to absorb force while landing from a max effort vertical jump before taking off again. This is similar to what a basketball player may experience when competing for a rebound.



Progressing Movement Direction


When progressing movement direction, I will typically progress an athlete into the frontal plane after the sagittal-vertical plane. The video below shows a possible progression for frontal plane hops. We begin with lateral hurdle hops. There are two important details to address during the first progression. First, the hurdle forces the athlete to emphasize the vertical plane more, which can help to reduce the sheer and rotary forces at the knee during the landing phase. Second, performing lateral hops first creates a varus force at the knee while landing. This increases the likelihood that a bad landing will result in knee varus. Although knee varus is not ideal while landing, it is a better option than knee valgus, which is a mechanism for ACL injury. Lateral hurdle hops can then be progressed to medial hurdle hops. These can both be progressed by removing the hurdle and repeating the same sequence. By removing the hurdle, sheer forces at the knee are increased, thus increasing the demand for stability at the hip, knee, and ankle. Finally, we can add a transverse plane component. In a similar fashion, we begin with 90d lateral hops that will result in a varus force at the knee while landing. This can be progressed to a 90d medial hop if you feel the need, but I would recommend keeping the intensity low, as this creates a pretty substantial valgus force at the knee when landing.



When programming frontal plane bounds, the order is flipped. We would perform medial bounds before lateral bounds, as lateral bounds result in a valgus force at the knee when landing. We can also use these same principles when programming transverse-vertical hops and bounds.


Linear jumps are typically the last movement direction I will program. The reason for this is that linear jumps tend to place the most compressive forces on the knee as well as anterior sheer forces, which is one of the mechanisms for an ACL injury. Below is a video of a linear bound progression. We start by performing a linear hurdle bound. Once again, the purpose of the hurdle is to increase vertical motion, which can help to reduce compressive and sheer forces at the knee during the landing phase. This is progressed by removing the hurdle. Next, we increase the forces experienced on takeoff by performing a drop linear bound. Finally, we can perform a multiple response linear bound. A similar progression can be used when performing linear jumps and hops.



Plyometric Programming


Plyometrics are meant to be explosive, they are technical in nature, and are demanding on the central nervous system. For these reasons, you want the athlete to feel fresh when performing their jumps, bounds, and hops. Plyometrics should be performed early in the training session, preferably after the dynamic warm-up, to ensure the athlete is not in a fatigued state. In addition, plyometric training should not feel like cardio. To insure your athlete has ample time to recover, allow one to three minutes between each set.


The total volume prescribed during plyometric training is just as important as the specific exercise itself. Even when performed with perfect technique, performing too high of a volume of plyometrics can result in unnecessary aches and pains from overtraining. If plyometrics are the focus for the training session, 40 to 60 contacts would be adequate to achieve the desired training effect (de Villarreal et al., 2009). If a movement skill, such as sprinting or changing direction, is the focus for the day, plyometrics can be used in an neural activation block for the upcoming movement session. In these cases, volume would be reduced to about 20 to 30 total contacts per session. Below is a table that can be used to aid in the programming process. As a general rule of thumb, when determining plyometric volume, less is more. Prioritize intent with every repetition and ensure adequate rest is obtained, both between sets and between training sessions.


Wrapping Up


What we have just discussed is a snapshot into what plyometric initiation and progression can look like. There are literally hundreds of plyometrics to choose from, and your athletes will respond differently to each of them. Programming plyometrics is an art. There is no one right way to program return-to-play plyometrics, but there is a wrong way. Be creative but follow the guiding principles. I encourage you to experiment with different movement progressions and different training volumes on yourself first. This will help you determine how long it will take to complete the exercises, what the exercises should feel like, and how your body responds to the training volume.


If you missed my last blog, which discussed the plyometric programming guiding principles, as well as how to initiate plyometric training, you can check it out here.


If you found yourself getting lost with the naming of certain plyometric exercises, click here to check out my blog over the basics of plyometric training.



References:


· Newton, R. U., & Kraemer, W. J. (1994). Developing explosive muscular power: Implications for a mixed methods training strategy. Strength and Conditioning Journal, 16(5), 20-21.

· Turner, A. N., & Jeffreys, I. (2010). The stretch-shortening cycle: Proposed mechanisms and methods for enhancement. Strength and Conditioning Journal, 32(4), 87-99.

· De Villareal, E. S. S., Kellis, E., Kraemer, W. J., & Izquierdo, M. (2009). Determining variable of plyometric training for improving vertical jump height performance: a meta-analysis. The Journal of Strength and Conditioning Research, 22(5), 1705-1715.