The Importance of Plyometrics in ACL Rehabilitation: Dive into the Melbourne Protocol and Mick Hughes’ Research

Anterior Cruciate Ligament (ACL) injuries are among the most debilitating injuries in sports, particularly in activities that involve rapid changes in direction, jumping or pivoting. Rehabilitation from an ACL injury is a complex and multifaceted process that requires careful planning and execution. Plyometrics, a form of exercise that involves explosive movements to increase power and agility, plays a critical role in the latter stages of ACL rehab. In this Pro Health Physio blog, we will explore the importance of plyometrics or neuromuscular training in ACL rehabilitation, with specific reference to the Melbourne Protocol and the research conducted by Mick Hughes, a renowned Australian physio and sports injury specialist. We will also provide examples of effective plyometric exercises that you can incorporate into your own rehab, irrespective if it is an ACL injury or not. .
Understanding Plyometrics and Their Role in ACL Rehabilitation
The term “plyometrics” originates from the Greek word pleythyein, meaning “to increase or augment.” While plyometric techniques were practiced in Eastern countries as early as the 1960s, the term itself was first coined in 1975 by American track and field coach Fred Wilt. After studying Dr. Verkoshansky’s training methods extensively, Wilt combined the Latin roots pilo (meaning “more”) and metrics (“to measure”) to create a term that reflects the purpose of plyometrics: enhancing an athlete’s speed and power. In essence, plyometric training aims to make movements more explosive. Although it began in track and field, this training approach has since proven beneficial across a wide range of sports, helping athletes improve their performance regardless of their discipline.

Plyometric exercises are designed to improve the muscle’s ability to produce and absorb force quickly, which is essential for activities such as jumping, sprinting and changing direction. These exercises involve a stretch-shortening cycle, where the muscle is rapidly stretched (eccentric phase) and then immediately contracted (concentric phase). This type of training enhances neuromuscular coordination, strength and power, all of which are critical in the rehabilitation of ACL injuries. This is why, at Pro Health Physio, we value these exercises so highly. One of the key goals in ACL rehabilitation is to restore the knee’s strength, stability and function to pre-injury levels, or even better. Plyometric exercises are particularly effective in achieving these goals because they mimic the dynamic, high-impact activities that are often responsible for ACL injuries in the first place. By progressively introducing these exercises into a rehabilitation program, patients can regain the explosive strength and neuromuscular control necessary to return to sports safely and effectively.

Lateral hopping

The Melbourne Protocol: A Structured Approach to ACL Rehabilitation

The Melbourne ACL Protocol is a comprehensive and evidence-based ACL rehabilitation program that has gained recognition for its effectiveness in guiding patients through the recovery process. The protocol is divided into several phases, each with specific goals and criteria that must be met before progressing to the next phase. Plyometrics are introduced in the intermediate and advanced phases, once the patient has regained sufficient strength, stability, and range of motion in the injured knee. These exercises are used to challenge the knee in ways that replicate the demands of sports, helping to prepare the patient for a safe return to activity.

Banded Plyos

Plyometric Exercises for ACL Rehabilitation

Incorporating plyometric exercises into ACL rehabilitation can be highly effective when done correctly. Below are some examples of plyometric exercises that we often use at Pro Health Physo in the intermediate and advanced stages of ACL rehab
1. Box Jumps
Box jumps are a fundamental plyometric exercise that helps improve explosive power and knee stability. Start by standing in front of a sturdy box or platform. Bend your knees and hips slightly, then jump onto the box, focusing on a soft landing to minimise impact on the knee. Step down and repeat. This exercise can be progressed by increasing the height of the box or incorporating a lateral movement before the jump.
2. Lateral Bounds
Lateral bounds are excellent for improving lateral stability and mimicking the side-to-side movements often seen in sports. Start by standing on one leg, then push off laterally to jump to the other leg. Land softly and immediately push off in the opposite direction. This exercise challenges the knee’s ability to stabilizestabilise during dynamic movements, which is crucial for preventing re-injury.
3. Single-Leg Hops
Single-leg hops are an advanced plyometric exercise that builds unilateral strength and balance. Start by standing on one leg, then hop forward, focusing on landing softly and controlling the movement. This exercise can be performed in different directions—forward, backward, and laterally—to challenge the knee from various angles. The knee is responsible for absorbing 65% of the forces when landing so this is a crucial test for it.
4. Depth Jumps
Depth jumps involve stepping off a box, landing softly on the ground, and immediately jumping as high as possible. This exercise helps improve the stretch-shortening cycle and increases explosive power. Depth jumps should only be introduced when the patient has demonstrated good control and strength in other plyometric exercises.
5. Tuck Jumps
Tuck jumps are a dynamic exercise that involves jumping straight up and bringing the knees towards the chest at the peak of the jump. Focus on landing softly and maintaining proper knee alignment throughout the exercise. Tuck jumps are great for improving vertical jump height and knee stability.

There are many variations of these exercises which can be helpful to identify how an athlete generates force, absorbs force and the transition between these two variables. We are also well trained in dealing with the psychological impact an injury can have on athletes. We refer to low level plyometrics as a’leap of faith’. This relates to the competence, confidence and capability to perform a jumping movement. This is scary for those who may not have performed a jump for 6+ months since their injury, operation and post op care.

With a graded strength approach, systematic rehabilitation process as outlined in the Melbourne ACL protocol, and the supportive/empathic guidance of a skilled therapist, we can guide you every step of the way back to your sport and passion. In our opinion, if you have not completed a plyometric assessment with a therapist or coach, you have not completed your rehabilitation.

In conclusion, if you or someone you know is recovering from an ACL injury, be sure to consult with a physiotherapist who is knowledgeable about the Melbourne Protocol and the role of plyometrics in rehabilitation. By integrating these exercises into your rehab program, you’ll be taking a significant step toward a successful recovery and a strong, resilient return to your sport.

For any queries about ACL injuries, pre or post operative surgical management, return to running/sport or play, please drop us an email and we are happy to guide you through the process at Pro Health Physio NE via admin@prohealthphysione.com or book via website.

From all the team at Pro Health Physio,

James Nowosielski

Senior MSK Physiotherapist