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How To Use The Decline Board Squat To Improve Quad Strength After Knee Injury

Written by: Nick Jack
Category: 2014
on 16 May 2017
Hits: 26389

When planning to start the long process and break up the progressive stages of a knee rehabilitation program, an understanding of what can influence movements from a mobility and stability perspective is critical. Many of the best exercises to develop strength into weak areas are not necessarily the best option in the early stages as the body compensates and adapts to the pain and injury. Using various tools and drills to "retrain" the brain and nervous system is very important in being able to restore efficient functional movements of the body. The quadriceps can be a real problem in the beginning as they may have contributed greatly to creating the injury in the first place, and are often left with excessive tightness and weakness. This makes it very difficult to strengthen without creating more pain, and also more dysfunction. In this article, I am going to explain the role of using the Decline Board Squat to overcome this problem. I will show you how to gradually progress to heel plate squats, to eventually floor based squats and pain free movement. The purpose of the decline squat is to improve the overall strength of quads while maintaining muscle balance and optimal movement pattern of squatting.

Why The Decline Board Squat Works

I first started using this equipment back in 2006 when working with some clients trying to rehab after an ACL reconstruction. There was no possible way they could squat correctly, or with much range as there was significant stiffness in almost all joints greatly reducing their ability to achieve the optimal depth needed to develop strength. I found the ankle was playing a huge role in preventing the optimal squat technique, and in many cases was the cause of the knee injury, and I needed to find a way to take the ankle out of the equation temporarily so we could improve strength into other areas.

I had recently completed a training course on rehab and the physio taking the course had shown me how to use the decline board to help with this particular problem and also teach the client how to maintain optimal spinal and trunk position during the squat. Not only was this important for retraining the movement pattern of squats as they improved, but it also taught them how to recruit the posterior muscles of glutes and hamstrings more effectively by shifting their body into a more centred position. The ankle we could then treat separately with the eventual goal of integrating it all back together to improve the movement without compensation and add strength to muscles that had already wasted due to the injury.

More recently I suffered an ACL tear myself, from a freak accident playing sports, so now I had a chance to experience this exercise first hand from a point of real weakness and instability. And I can tell you that without doubt this played a major role in being able to regain lost muscle and function into my legs again. It did not cure me, but prepared me for the following phase of rehab with better mobility and stability to do the exercises that would restore me back to 100% strength.

Watch the video below of an example of the how decline board works.

There has been many studies completed to evaluate the success of using this. 

“The research used elite Australian volleyball players with patellar tendinosis in a randomised controlled trial lasting 12 weeks, with a 12-month follow-up. Participants had to complete their exercises twice a day for 12 weeks. They performed 3 sets of 15 repetitions during a session. All exercises were completed on a single (affected) leg to about 60 degrees of knee flexion, with participants being taught how far to squat down during their initial session. Participants progressed load by adding weight to a backpack in 5kg increments. The group used a 25-degree decline squat board. They completed the downward component (eccentric phase) of the squat on the symptomatic leg, and the upward component (concentric phase) on the asymptomatic leg. They were instructed to exercise into moderate tendon pain and to progress by increasing load if this pain eased. By the end of the 12-month follow up period, there was a significant improvement in the ability of this group to carry on their full sporting activities compared with a control group who had undertaken a more conventional rehab program.”

Research reported in MA Young, JL Cash et al, ‘Eccentric Decline Squat Protocol for Patellar Tendinitis in Volleyball Players’, Br J Sports Med, 39 (2005) 2, pp 102-105

Another great study you can check by clicking here

In this particular study they found many great things but reinforced what I had seen first hand over the past 11 years. I suggest reading the full article to see all of the findings but here is one part that I found referred to the quadriceps function (rectus femoris) in particular.

"Squat exercises on the decline board showed significantly higher muscle activity of the Rectus Femoris and significantly lower muscle activity of the Tibialis Anterior at knee joint angles of 45°, 60°, and 90°, compared with squat exercises on the flat floor. Moreover, with a knee joint angle of 90°, the muscle activity of the Gastrocenius Lateralis was significantly low. That is, in squat exercises on a 25° forward-tilted board, subjects attempt to compensate for the sensation of falling forward by moving the trunk backward. As a result, the ankles, knees, trunk, and head all move behind the line of the center of gravity, increasing the external movement that unfolds the knee joint.

Hence, when the knee joint angle is 45°, 60°, and 90°, squat exercises on a decline board result in more external movement than squat exercises on a flat floor, significantly increasing the muscle activity of the Rectus Femoris. Moreover, with squat exercises on a decline board, plantar flexion of the ankle joint occurs in order to maintain body posture and balance, unlike with squat exercises on a flat floor. This causes relatively small muscle activity in the Tibalis Anterior and Gastroc. In the future, it will be necessary to investigate how decline-board squat exercises and the knee joint angle affect the muscle activity of the upper limbs."

These studies show that by using tools like the decline board to assist the body in achieving a range not possible from the floor, you can achieve the result of adding some lost muscle in areas of weakness. But it is not all about adding muscle, for if it were we would just use a leg extension machine which can isolate the quads better than any other exercise. More on this shortly.

When using this exercise I like to do 3-4 sets of 6-10 reps with a 3-5 second isometric hold at the bottom for each rep. The holding is more beneficial than adding a load like a barbell or dumbbell for the time under tension is easier to control. Also the added load tends to stiffen the thoracic spine and place additional stress into the joints. By keeping it to body weight you are still emphasizing range of motion and depth which is more beneficial for this exercise than added muscle. It is easy to confuse strength with mobility and stability and an area where this exercise is abused.

Trying to strengthen muscles that are not providing enough mobility or stability at their respective joint is a disaster waiting to happen. Strength does not over ride stability or mobility instead it is created from it.

You Must Develop Stability Before Strength

The biggest mistake many people make in the rehabilitation process is trying to develop strength before ensuring they have optimal stability and movement. The thinking is that if a muscle is weak and you make it stronger everything will be fine. Unfortunately it does not work like that. 

Machine training exercises like leg extension machines, leg press, and leg curls allow for people to skip the stability stage and go straight to strengthening. This is a potential disaster as your body learns that it does not need to provide STABILITY to the joints in order to move. Worst of all is the fact that the brain and nervous system are being shut down while the machine does their work. Sure, you may be able to build muscle but you will do this at the expense of balance, stability, spinal position, coordination and how to sequence timing and activation of almost every muscle activates within your body. This is where people set their body up for years of chronic pain and limited movement.

You can read more about the dangers of machine training in these articles.

What you must understand about knee pain is that it is often joints above or below the knee that are the real problem. Until you identify and resolve these problems you will continue to suffer with knee pain. This part can e a bit complex to explain for what you will find is that the knee is affected by the capacity of joints above (hip and pelvis), and below (ankle and foot), for it to maintain optimal alignment during movement. The knee is caught in a crossfire and dependant on these joints to perform their roles correctly to maintain perfect alignment. If any of these joints are unable to complete their role effectively it disrupts the optimal alignment of the patella in the knee and now you are set for trouble as it will be impossible for the patella to track correctly when the knee is fully flexed.

When you lower body into a squat position the knee cap engages into the trochlear groove (track) and is guided down the femur and as you straighten the knee when you begin to stand up the patella tracks back up the groove. This is what is known as patella tracking.

The inside of the joint is covered in articular cartilage designed to reduce the stress that occurs in the joint created by the quadriceps. However, if you lack the correct alignment of the patella in the trochlear groove you can end up with increased stress within the joint usually on the outside or lateral part of the knee as the larger more powerful quadriceps muscles begin to take over the work from the VMO. And eventually this stress becomes pain! This is where you see foam rolling on the outer part of the thigh, (ITB) to release this tension. This may help to some degree.

However, on its own it will do little for it isn't just tightness on the outside of the leg that can produce issues. Weakness and or timing issues of the medial stabilizers can also cause the knee cap to track incorrectly when you move. This is where many people are told to strengthen the VMO in the belief that isolating this muscle with strengthening exercises will automatically correct the problem. Once again though this will do very little if this is all you do.

To finish the job you need to ensure all of the muscles involved in movements like squats and lunges work together. Some muscles are more concerned with stability and deceleration, while others are focused on locomotion and acceleration and all of this happens in a blink of an eye. While it may appear for a certain muscle to be weak or tight, addressing it individually ignores how this muscle is truly used and the interaction it has with its synergistic partners.

I suggest to read the articles below for more detail on this.

Okay so where do you start? We know you need to build up the strength into the quadriceps so what is the best way to build strength? As I have alluded to it is more about improving movement first and strength second. Improving movement funnily enough builds strength faster than any other method anyway, but without the risk of load and compression of joints that pure strength training requires.

Improve Mobility First

After a knee injury or even for chronic knee pain sufferers the damage caused around the knee and the massive swelling instantly atrophies all of your quadriceps muscle leaving you feel very vulnerable and unstable.

Research has found it only takes a teaspoon of fluid on your knee to shut down the VMO muscle! After a few weeks this weakness turns into stiffness as the body creates scar tissue and a way of creating stability at the knee in order to protect itself from more pain. This stiffness inhibits how we move and as a result we now learn new ways to do functional movements like squats, walking, etc. The longer the compensation remains the worse it gets in the long term. The use of the decline board does not start right now, you must do a few other things first. 

Before going straight to squats and trying to strengthen muscles we need to be certain that the joints needing mobility are able to do this. Flexibility and mobility restrictions will inhibit movements, and you will find it is often these things that created your injury in the first place!

First thing you need to do if you want to improve the squat form, is to work on mobility of the ankle and the hips. It is these two areas that cause movement compensation, and start the process of muscle weakness, usually beginning in the glutes, feet, and eventually in the VMO.

You will find great articles to read more about this below that provide you with several examples of stretches you can use.

Stability Exercises

Many people who easily pass the mobility tests, and even the isolated strength tests will often fail these simple stability assessments. This tells you there problem is more to do with weakness than tight muscles.

The very first thing I look at is foot stability and in particular the big toe function.

It makes sense to start at the feet as they are the first part of the body to touch the ground when we move. Our feet and ankles are meant to withstand incredibly high forces and should provide more in terms of shock absorption than perhaps any other body part. Unfortunately, we begin to gradually lose this ability once we start wearing shoes. Over time, the feet, ankles, and toes become inhibited. And as we expose our feet to some trendy shoes with all types of padding and support, this only make matters worse and exacerbates the lazy and weak feet muscles.

Besides minimizing the ability to withstand intense ground reactive forces, the body gradually begins sending fewer and fewer signals to the feet, leading to distortions in pro-prioception and loss of innervation all the way up the kinetic chain. This is where poor stability evolves and injuries are born! 

I like to combine specific foot exercises into a single leg stance exercise called the Toe Touch Drill that teaches people how to control stability of the foot and hip simultaneously. I regularly use this with clients in their 80’s for preventing falls, and people suffering with serious hip or knee injuries, as it helps to restore optimal stability of the pelvis with the single leg stance used in walking. At the same time I also include this in training programs for elite athletes for improving sporting performance with running and jumping movements.

Watch the videos below to see more about this.


I also like to use a lot of strange exercises called "iso-integration exercises" that try to activate the weaker glutes and foot muscles within integrated movements. The concept behind these exercises is to use a band pulling the knee inwards in order to force external rotation from the hips via activation of the glutes. This is quite a clever way of forcing the body to respond and can be one of the key methods to eliminating the problem once and for all. The band is really trying to make you do it wrong so your body has no choice but to respond.

If a person has significant weakness at the glutes or even simply a poor understanding of movement to keep a well aligned knee, the body is forced to find another way to maintain this alignment. What it will often do is move the foot onto the outside part of the foot, which solves the problem of faulty knee alignment, but ruins your ability to stand up well balanced as you have only half of your foot on the floor. If the foot pronates to neutral like it is supposed to, the hips roll inwards forcing the knee into the horrible position again. This is easily seen when we put someone onto one leg with exercises like the Toe Touch Drill or the single leg deadlifts and squats we are about to discuss.

Recent research has found by actively attempting to internally rotate the tibia inwards, the VMO will increase its activation potential. This may be due to the fibres of the VMO also act to internally rotate the tibia through the patella.

You can watch two videos of these exercises below.


I also suggest to read the full article - How to use iso-integration articles to improve stability of the knee

There is obviously a ton of other things I would look at but this gives you a great starting point. Combined with your hip and ankle exercises you now are set to take on the difficult task of improving the squat.

Progress To Squats With Increased Range Of Motion Using Heel Plates

Once you have implemented your mobility and stability exercises I would begin using the Decline Board Squats.

Remember the main purpose of this is to restore full range of motion at the knee joint but with great control and stability.


  1. Standing with a barbell resting on your upper back hands slightly wider than shoulders with your feet on a ramp or heels resting on small weight plates.
  2. Lift your chest up to activate your upper back muscles and drive the elbows forward. Take a comfortable stance wide enough that allows you squat down between your legs.
  3. Take a deep diaphragmatic breath then draw your belly button inward.
  4. Lower down into a squat as low as you can keep the natural arch in your low back and no pain in the knee. 
  5. Exhale through pursed lips as you return to standing.

Sets / Reps: Complete 3 sets of 8-12 Reps with 5 second hold at bottom.

Once you feel you are competent and comfortable at these squats, and your knee joint range of motion is almost at full range, you can then slowly progress to trying to squat close to the floor with full depth. Again we would use tools like heel plates and also a stick to assist in the process of learning how to do this correctly. But I must stress you need to be certain you can achieve full flexibility and also have no pain present. This squat is transition from the decline board to getting to the floor. This is where you begin to see the mistakes take shape and the real learning begin.

Watch the videos below to see examples of mistakes we often see in the squat, and the second video where I show you how to use the heel plates.


Once you are confidently completing 3 sets of 8-12 reps with body-weight you can begin to progress to the more challenging strength exercises.

Strength Stage

Now that you have improved mobility at the ankle and hip, improved stability at the foot and hip and learned how to move correctly with squat the last thing to do is strengthen the system so it can withstand any force or load.

You will need to spend time strengthening the body for ALL movements and not just the squat. Learning how to complete deadlifts, lunges, step-ups and if you play sports you will need to learn how to run correctly and execute highly advanced agility movements to ensure full integrity of the knee. This stage can take considerable time to get right but it is absolutely critical you spend the time to do it correctly. 

It should not come as a surprise that poor performance, injury, and pain is the end result from using poor training techniques. What does come as a surprise to people is how difficult it can be to change a faulty movement once it is encoded into your nervous system. Technique is everything!

A great quote that really stuck with me about exercise technique and its value to preventing injury and pain is in the book “Corrective Exercise Solutions for Hip & Shoulder” by Dr Evan Osar. He says,

"It is much harder to detect the subtleties of compensatory movement in the early stages although easier to correct them, and much easier to detect errors in chronic movement dysfunction however they are much more difficult to change."

This is so true.

Over the past 14 years in our rehabilitation program we have worked with so many people suffering with really complex cases of injury and pain that took a long time to help the person find relief and a solution. Sometimes the dysfunction was so great we could not find a solution and the best we could do was to find ways to manage the problem.

The most important point is that in ALL of these cases the problem could have been very quickly corrected or prevented if we saw the person BEFORE they began exercising, and were taught efficient strategies of movement. Their ignorance to quality of movement with endless repetitions of poor form eventually broke down their body’s structure.

You can begin to see my frustration knowing how easy exercise can be when you have been taught correctly from the start.

To see more about how to strengthen your body with these various other patterns check out the links to the various articles below.

Do You Need More Help?

There is a ton of additional exercises I would explore for knee pain and this article only touches on them briefly. For more help you will also find our Knee Pain program shown below which I highly recommend getting a copy of if you are struggling with knee pain right now. This includes a 60 minute video and PDF report to show you how to implement the assessment process to identify mobility & stability restrictions along with movement pattern dysfunction creating your knee pain. These programs provide over 70 exercises and teach you how to design your own program based on your test results to correct your weakness.

Click here to go straight to the online shop or on the image below to see more.



I hope this article helps to show you how useful it be to use a Decline Board Squat for improving not just your overall muscle in the quadriceps but the movement pattern of squats which we use in daily life with activities like sitting in a chair to jumping in sports. Too many rehab programs focus just on either loosening tight muscles or using isolated strength exercises to remove pain, when we need to take a broader look at how we move, and how to improve overall stability and mobility and what role the rest of the body plays in maintaining the perfect patterns of movement that make us move efficiently.

Only then can you truly be rehabilitated and be able to live life free of pain and limitation or get back to playing sports at full potential without risk of further injury. 

Last if you live in Melbourne and would like help with a health and strength training program you can fill in the form below to request a free Postural and Movement assessment.

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About The Author

Nick Jack is owner of No Regrets Personal Training and has over 15 years’ experience as a qualified Personal Trainer, Level 2 Rehabilitation trainer, CHEK practitioner, and Level 2 Sports conditioning Coach. Based in Melbourne Australia he specializes in providing solutions to injury and health problems for people of all ages using the latest methods of assessing movement and corrective exercise.


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