The role of plyometrics in injury rehabilitation

This article was co-authored with my colleague Peter Colagiuri at BioAthletic. Colagiuri is release an upcoming app for sports injury diagnosis. You can learn more at Sports Injury Online.

When we talk about plyometrics, we are talking about a very broad category of movements. The one thing they have in common is that they involve rapid stretching and shortening of contractile and elastic components of muscle. When it comes to rehabilitation, this category is unfortunately often brushed over or completely forgotten. In this article we hope to show some ideas on how and why plyometrics should be included in the rehabilitation spectrum.

Before we talk about plyometrics in rehabilitation, it helps to understand a bit about what we’re talking about. Plyometrics can come in many forms: jumping, hopping, bounding, landing, counter-movements, pretension, elastic impacts and more. As mentioned above, plyometric training focuses on the stretch-shortening cycle and elasticity. By By maximizing these components of movement, efficiency is optimized by the return of elastic energy throughout the body. This not only improves performance, but also reduces the risk of injury by improving the tolerance of connective tissues to high force and high velocity loading. These factors are just as important in rehabilitation as they are in standard training.

» Learn more: Leigh Egger and Frans Bosch walk through hip lock exercises in HMMR Classroom Lesson 15.

Plyometrics in rehabilitation

When it comes to rehabilitation, plyometrics are all too often forgotten in the mid or late states due to the perceived risk and difficulty in controlling tissue loading in plyometric exercises. Instead, return to play protocols disproportionally focus on concentric, eccentric, proprioceptive, slow and low-force movements.

Plyometrics are a key element of sport, therefore they cannot just be skimmed over or missed in the rehabilitation plan. As research presented Chris Beardsley and others continue to show, strength-training is very specific in the adaptations it produces. If you avoid properly preparing the athlete for the specific demands of the game, including plyometric movements, the risk of re-injury skyrockets. For example, the difference between an isotonic single-leg calf raise exercise and a field-based acceleration is chalk and cheese in terms of the total force and rate of force development involved in the calf muscle complex. One can’t expect to adapt to a basic level of activity, and then jump up tenfold in intensity and continue competing with no issue.

One can actually make the case that plyometric activities are even more important in the rehabilitation process than in normal training. To start with, the elastic element is generally under-trained, making athlete more vulnerable to weaknesses there upon return to full loading. Added to that is the detraining effect. Research shows that muscle and tendon changes associated with plyometric activities detrain at faster rates than other qualities. For example, one study showed that adaptations are reversed back to their pre-plyometric training levels after just a four-week layoff.

Detraining is one of the biggest factors to consider in a rehabilitation train, and athletes need to give extra focus to rebuilding tendon extensibility and active muscle stiffness before returning to competition. It is also hard to find the same adaptations in tendon extensibility and active muscle stiffness through other means, with plyometric training being far more effective than other methods such as isometric training.

Case studies: lower limb tendinopathies in rugby

The work of physiotherapists and researchers such as Ebonie Rio and Jill Cook have been presenting for some time on the pitfalls of previously accepted tendon rehabilitation protocols. Traditional practice is biased towards eccentric exercises and heavy and slow movements. These offer very little in allowing tendons to adapt to the energy storage and release demands, compressive loads and motor control deficits that occur in tendinopathic injuries.

With the above in mind, there are often cases where we see rugby players in our injury clinic with tendinopathic reactions that simply do not respond to passive or low-intensity exercise rehabilitation. But once we introduce multi-directional landing drills prior to training, they’ve been able to reduced their symptoms and continue competing within a matter of days. We feel this is from manipulating the highly adaptive nature of tendons to their advantage.

Example 1: ankle sprain

Ankle sprains are a huge burden in professional sports. The talocrural joint is very symmetrical and inflexible in the dorsiflexed position when compared to the ‘looser’ toe-off/plantarflexed joint position. It is also exposed to very high forces in a matter of milliseconds when dorsiflexed. The muscles and tendons of the shank/ankle are required to brace isometrically and provide stability in a vulnerable spot. This is particularly so with change of direction movements.

Additionally, the ankle and hip are intimately connected. Studies have demonstrated an increased risk of lateral ankle sprain with increased hip abductor weakness. Despite these points, the combination of ankle and pelvic control at high speeds under time-pressure are rarely combined in traditional ankle sprain rehabilitation. Standard rehabilitative and training strategies haven’t caught on to the idea that plyometrics and coordination based ankle rehab could possibly be very powerful in the prevention and reduction of ankle sprains.

Here is one example of how that might look in training. The load above the head demands greater pelvic control. Hopping rapidly on (or off) the step requires an early active plantarflexion action just before foot contact. To properly execute, the focus must be on the speed and sound of ground contact.

Example 2: Knee pathologies

Rate of force development is of enormous importance in attenuating landing forces and sprinting mechanics post-injury, whereby a significant amount of arthogenic muscle inhibition can impact type 2 (fast twitch) fibers and their performance. This is particularly the case post-operatively (e.g. ACL reconstructions, arthroscopes etc). Often we will observe athletes recovering from these knee pathologies with significant deficits in their ability to control a stiff, braced knee upon landing or running. This compromised control and coordination must be addressed through building blocks in gym rehab, and consolidated with progression to field/court based training before full RTT/RTP is advised. Here is one example of how we might incorporate plyometric training to work on such knee pathologies:

Where to start

Plyometric training is a vast and varied area. So where do you start? It doesn’t have to be about amplitude. We prefer focusing on a few other factors in exercise:

  • Time-pressure;
  • Multi-planar;
  • Velocity dependent;
  • Perturbation and/or unstable loads;
  • Complex coordination; and
  • High demand.

This might sounds like a mouth full, but it doesn’t have to be anything too complex. The examples above show how simple and effective plyometrics can be. They don’t have to focus on the all the factors, even a few can help helpful. Another example are variations of stair exercises where athletes bounce off two steps. This focuses on short contact times and ensures the athlete cannot collapse into eccentric muscle action or deep dorsiflexion: