Here’s a quick recap of our stance on ACL rehab from part 1 of this series. 

Many ACL rehab protocols are designed to avoid knee valgus collapse. However, this is a shortcoming as this position is nearly impossible to avoid. The knee needs to be prepared to resist and control valgus forces which occur in sports AND day-to-day life.

This can be done through progressive adaptation; this will allow your body the opportunity to safely produce stronger and healthier tissues by imposing stress to the area. You need adequate stress and the appropriate amount of force to strengthen the knee and the tissues (muscles/ligaments/tendons) to be able to support the activities you want to be able to do. 

We’re going to share examples of ACL rehab exercise progression and progressive overload. These concepts and progressions were learned from Gary Gray of The Gray Institute.

The principles of Resources and Demand are used in Gray’s progression of exercises. Resources describe the ability of other regions to help stabilize the knee (ie. the hip, trunk, or ankle). During the initial stages of rehab, you want more resources to prevent inappropriate or excessive forces at the knee joint. As the knee becomes stronger, it will be able to take on more stress, and resources can be gradually reduced.

Demand describes the intensity of mechanical stress imposed on the knee. Specific to ACL rehab, it refers to the intensity of valgus force to the knee. You can add demand by increasing the length of exercise, and speed of movements, or including movements that produce a valgus force. In the early stages of rehab, demand should be minimal and gradually increased. 

Check out this example of beginning-stage exercise progressions of ACL rehab following this principle. We will utilize these three exercises in this example.

1. Same-side foot reach

2. Opposite lunge

3. Bilateral leg squat

Let’s say the client you are working with recently underwent an ACL repair. The most appropriate exercise to start with is (1) Same side foot reach (shown above). This exercise has minimal demand on the involved knee because the majority of the weight is on the opposite side. It gives you many benefits because it allows you to turn on the resources around the injured knee.

The next step will be (2) Opposite side leg reach (shown above). There is more demand on the knee with this because it requires more weight bearing on the injured knee. Initially, you step in the direction that maximizes resources. To accomplish that, you step towards the side of the injured knee, which maximally loads your hips on the same side, thus resulting in maximum protection.

(3) Bilateral squats (shown above) add a little more translation and therefore demand on the knee. We can also add more resources to this exercise in the beginning. Standing in a narrow stance and staggering your injured leg backward, creates internal rotation of the hip and inversion on the ankle. This activates the muscles of the hip and pulls the knee away from the valgus.

After performing bilateral squats in a staggered narrow stance, we can revert to leg reaches. Anterior and posterior reaches will put more demand on the injured knee. Since this is a less mechanically advantageous position, it has less reliance on the hip than the previous reach, thus fewer resources to protect the knee. 

The next possible progression could be a neutral stance bilateral squat. Again, per the same principle of less reliance on resources, the demand is higher on the injured knee. After that exercise, we can revert to anterior and posterior reach, but with added weight or longer duration to add more demand. Then, we can progress to opposite side reaching toward the side of the injured knee, but with a faster velocity, or a hop.

As the knee becomes more resilient, you can keep progressing with exercises using the same principle- adding more demand and less reliance on resources. Ultimately, you will strengthen the knee to the point where it could withstand any scenario of stress in the sport or activity you play. There is no universal exercise program that applies to everyone. This is why coming up with an individualized program is considered an art. A key point to remember is to understand what kind of demands are put on the injured knee and how to tweak the resources to either protect the knee or increase demand. This allows one to reach the ultimate goal of creating a knee sustainable to multidirectional stress.