In this post, we discuss how more weight can produce worse results in rehabilitation and training more generally.
At a glance
More load does not always mean better results — it can actively reduce activation in the muscles you’re targeting.
The nervous system will recruit stronger muscles to manage heavy load, bypassing weaker ones.
Specialised sensors in tendons and muscles can suppress muscle output when load feels threatening.
Injury and pain lower the threshold at which these protective responses kick in.
The brain anticipates threat and can reduce motor output before a rep is even completed.
Getting the load right — not maximising it — is the prerequisite for progress.
Introduction
The assumption that heavier is better is deeply embedded in gym culture. You’ll see it everywhere from the marketing of products, to the way members train in gyms themselves.
You’re probably aware that this approach can lead to injury, but I want to talk about something subtler. Something that occurs before injury and that can nevertheless impede your results, especially if you’re currently recovering from pain and injury.
Too much load can reduce the contribution of the very muscles you’re trying to target.
Let’s take a look at how this happens and what you can do to ensure it doesn’t.
How the nervous system controls muscle activation
Have you ever helped a friend move house? Remember trying to get the couch up the stairs? How did you approach it?
You probably recruited as many people as you thought were necessary for the task and you all worked together to spread the load as evenly as possible.
Save for a few choice expletives, this is exactly how your nervous system organises the task.
The crucial point here is that you don’t have much influence on how your nervous system gets the job done.
So how does it accomplish this? And what systems must you work with to achieve optimal results?
Synergist dominance: When the wrong muscle does the work
Let’s continue with our house moving example. Among the people you’ve recruited to help get the couch up the stairs are Steven, a computer programmer, who hasn’t lifted anything heavier than a joystick for the past 20 years; and your uncle Frank, a former rugby player who knows his way around a gym.
Who’s your money on to do the majority of the lifting? Frank? Mine too.
Under heavy load your nervous system will make exactly the same call. Stronger muscles will dominate the movement and weaker ones will be bypassed.
The only way you’re going to get Steven involved is if you give him an easier task. This will involve reducing the load and perhaps even designing the exercise so Frank can’t contribute much at all.
Golgi Tendon Organs and muscle spindles
Once you have the perfect exercise that isolates those weaker muscles, there are further things to consider.
Your body is stacked full of sensors that make the average Formula One car look like a Ford Cortina.
These sensors reside in a variety of areas including your skin, ligaments, tendons, joints, and most important of all, muscles.
Deep within the tendons of muscles sit specialised sensory receptors called Golgi Tendon Organs, or GTOs. Their job is to monitor tension. When that tension rises to a level the nervous system considers threatening, they fire — reducing tension in the working muscle. It’s your body’s built-in protection against injury.
The key variable is where that firing threshold sits. After injury or prolonged pain, the nervous system becomes more vigilant and reactive, meaning the reflex can trip at lower levels of tension than it would in a healthy, settled system.
Muscles themselves contain sensory receptors known as muscle spindles. They provide feedback on the length of muscles and any changes to that length over time.
Similar to GTOs, the nervous system can alter muscle spindle sensitivity following injury. An increase in sensitivity drives the muscle guarding and protective tension you experience after injury. Over time, sensitivity can also decrease — and when it does, the result is movement that feels uncontrolled or difficult to coordinate.
Arthrogenic Muscle Inhibition
When a joint is swollen or painful, your nervous system responds by reducing the ability of muscles in the surrounding area to produce force.
The most well-documented example is quadriceps inhibition following knee injury or surgery. Even in people who are otherwise fit and healthy, significant quadriceps weakness will persist — not because the muscle itself is damaged, but because the nervous system is attempting to protect the joint.
The implication for rehabilitation is critical: adding load when joint irritation is still present can amplify this suppression, not overcome it.
Pushing harder into an inhibited system doesn’t restore function — it gives the nervous system more reason to protect. Reducing irritation and restoring the joint’s sense of safety is what allows motor drive to return.
The brain’s role — descending inhibition and the threat response
Your nervous system doesn’t just react to what’s happening in the moment — it anticipates events.
The brain is constantly making predictions, and when movement or load is associated with a history of pain or injury, it can issue inhibitory signals before movement occurs. Protection, in this model, is proactive rather than reactive.
A heavier load may therefore reduce motor output before a repetition is even completed — not because the muscle is fatigued or the tissue is failing, but because the brain has already decided the situation warrants caution.
Evaluating the whole picture
In a rehabilitating client, or even someone who has experienced injury in the past, several of these mechanisms can operate simultaneously.
The combined effect is that more load produces less activation in the target tissue. This directly inverts the gym assumption — and it’s why getting the load right matters.
Summary
The goal in rehabilitation and training more generally isn’t to lift as heavy as possible — it’s to create the right stimulus in the right tissue.
Getting the load right is a prerequisite for progress.
Heavier loads have their place, but only once the system is ready for them.