Let me start with a quote (paraphrased) from world leading tendon rehab expert Dr Peter Malliaras.
“When injury rehab isn’t successful, either the patient is not doing the exercise right, doing the wrong exercise, or key progressions in the exercise process are missing. That leads to panic in patients and practitioners alike and alternative approaches are tried.”
Exercise is the key variable in injury rehab. Getting it right is the difference between success and failure.
With that in mind, let’s look at why strength training machines work best for injury rehab.
Resistance training machines allow you to isolate weak muscles.
When injury occurs, there’s a short term adaptation in the central nervous system (CNS). It finds another way to move you in order to off load the injured tissue.
Think of this as rerouting traffic whilst the road works are taking place.
Once the works have been completed however, you need to get the road open as soon as possible. If the diversion stays in place for longer than necessary, it will have unintended consequences elsewhere.
This holds true for acute injuries, such as muscle and ligament ruptures and also for chronic injuries like Runner’s knee for example.
Unlike patched up roads however, the injured site and probably other muscles in the area, will require specific attention to get them stronger again.
Think back to the use it or lose it mantra. If your CNS has avoided putting force through an area for sometime, it will be weaker.
The genius of your CNS is such that you can continue with your life and even return to your activities without really knowing you have this weakness.
In the runners I see for knee issues for example, many are shocked how weak their quadriceps really are once they’re isolated.
This despite returning to running (albeit with issues) and doing a bunch of so called functional type exercises such as squats and lunges.
See this post for a detailed look at how muscle compensation can influence injury rehab results.
Weak muscles will stay weak unless they are isolated. Strength training machines are the best way to do this.
This is one of the key principles of strength training and one that’s often overlooked in injury rehab.
Muscles will only adapt as far as they need to. This is an evolutionary effect. Why would your body waste valuable energy improving the strength of muscles if there’s no requirement?
In order to continue to stimulate strength gains, you need to gradually increase the demands imposed.
This takes time. Everybody seems to understand that exercise is a long term process and yet in rehab both patients and practitioners expect immediate results.
It takes around 8 weeks to produce a meaningful change within the structure of a muscle. That’s just the start of the process however.
To get the muscles strong enough to tolerate the activities you enjoy could take longer. Especially if they were weak to begin with.
Body weight only exercise can’t achieve this.
What I see on a consistent basis is how ineffective body weight only exercises are at doing this. They simply don’t enable progressive resistance to be applied.
Once you can do 15 leg lifts or whatever, then what? 20? The numbers become meaningless above a certain point as the loads aren’t sufficient to stimulate further change in the muscle.
Strength training machines are designed specifically with this purpose in mind. By using the incremental changes in resistance a weight stack provides, you’re able to progressively challenge the target muscles.
Take advantage of that.
The limitations of free weights.
The benefits of free weights and barbell training are eulogised everywhere you look.
Whilst they may be appropriate in certain situations, they have limitations. Particularly when your primary goal is injury rehabilitation.
The first is due to gravity. Because of this barbells only want to go one way, down. This limits which muscles you can challenge and by how much.
For example, how can you provide a meaningful challenge to your knee flexors with a barbell? You can’t.
A straight leg deadlift will only work your hamstrings in a lengthened position. There is no way to challenge these muscles into their shortened range with free weights.
Whilst a squat is thought of as a gold standard exercise, if you look at which muscles it actually challenges and by how much, it’s limitations become clear.
The quadriceps for example receive no stimulus whatsoever in the top position of this exercise. As you descend towards the ground the challenge increases until it’s maximal in the bottom position.
In rehab terms this presents a problem. If you’re a runner for example, which position of knee extension do you need to be strongest? The last 30 degrees.
This is where you’ll be asking your quadriceps to work hardest as they decelerate the knee flexion that results from your foot hitting the ground.
A squat will provide almost no challenge to this range whatsoever.
A muscle’s strength curve.
The second crucial point is that muscles are stronger in different parts of their operating range. Typically they are weaker in both their short and lengthened position and strongest in the middle of their range.
This represents a bell shaped curve as illustrated below.
Barbells can not account for this but intelligently designed strength training machines do. These machines will have a cam to vary the resistance according to the target muscle’s strength curve.
For example, a dumbell lateral raise gets difficult precisely where the muscles of the shoulder get weaker, the top position.
As you raise your arms to the side, the distance between the line of force (always straight down with a dumbell remember) and the axis (your glenhumeral joint) gets larger.
The is the reverse of what’s required to challenge the shoulder muscles. A machine like the Med X lateral raise however, is built precisely with that in mind.
This ensures the stimulus to the muscles and therefore the subsequent adaptation is optimal. It also reduces your risk of injury.
The stabiliser muscle myth.
It’s suggested that free weights challenge the ‘stabiliser muscles’ more than strength training machines. This is apparently because the path of resistance is not fixed.
Anybody who has attempted a heavy bench press will know this is not true. The path of resistance may not be fixed, but if you decide to push in any other direction other than straight up, you’re going to drop the weight.
When have you ever finished a bench press and noted your rotator cuff muscles were exhausted? Never. Because the stimulus is minimal at best.
If you really want to challenge the stabiliser muscles then the best way to do that is to isolate them as well.
The debate over the value of machines has been going on ever since their introduction some 40 years ago.
The negativity that surrounds them is based largely on opinion and not science.
This is frustrating because they provide an essential contribution to the injury rehab process. Understanding how to use them will get you back to your activities faster than any other training method currently available.
Get our guide explaining exactly how to use lower body resistance training machines to recover from injury and improve your performance.