Today I want to explain from a physio’s perspective the idea of load and specifically how it’s management is one of the essential tools in managing a patient’s injury, pain and eventually rehabilitation.
What is Load?
So what is load? Load is the physical forces that act on the body and or anatomical structures. These loads can come from the external environment (being tackled in footy) or they may result from
internal voluntary or involuntary actions of the individual (for example, lifting objects). This means anything we do puts load on our bodies, from the most basic of functions such as standing, walking, getting groceries out of the car to running, playing sports, to gym exercises like deadlifting.
What resists load in the body?
The musculoskeletal system is the internal load bearing structure in the human body, indeed within all vertebral animals. Our skeletal structure or our bones resist gravity and resist the stresses of muscle contraction for posture and movement, thereby undergoing compression and bending forces. Ligaments then connect these bones together specifically where they articulate in areas we call joints. They provide stability and protection of these joints. Tendons attach muscle to bone and transmit force and absorb shock. Lastly muscles generate force through contraction producing voluntary movements. Whenever the body is subjected to load either an external or internal load these structures and adjacent structures resist this load.
Why do we want to manage load?
When our bodies are put through function, load interacts with our bodies to create physical stresses, and according to our tolerance of these stresses the body responds in different ways. Firstly if the load is “safe” then the body undergoes positive remodelling of the affected tissue, where to put it in simple terms the tissues get stronger(this is the basis of gym work). If the load is unsafe (a one off safe load can quickly become unsafe if it is repeated more than the body can tolerate) then our bodies, specifically the affected tissue becomes injured which results in pain and reduced ability to function.
To further expand on this idea we break up this load and load tolerance into three categories;
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Acute trauma: this happens when the body is subjected to a single identifiable event. Such as when a patient is in a car accident, falls over and sustains a fracture, suffers collision on the sports field etc.
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Repetitive microtrauma over time: this happens when the body or tissue is subjected to accumulated microtrauma over time and once this exceeds the body’s/tissue’s load tolerance and results in injury and pain. A typical patient presentation is a pain that has no specific identifiable event, often has slowly gotten worse over time.
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The third way we can think about load and tolerance is that incremental load can be used as a tool to improve healing in injured tissue and also to trigger remodelling in the same tissue. Progressive, incremental increase of load is the basis of physio exercises and is the foundation of strength improvement and thereby increase in load tolerance.
Load management is a tool to prevent reinjury, improve tissue healing and ultimately improve load tolerance in context to the patient’s functional load demands.
How do we manage load?
We therefore use load management in a multifactorial way when a patient presents with pain or injury in the clinic;
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We identify the mechanism of injury and identify the functions that are loading the body/tissue to an excess of its load tolerance and as a result causing injury and pain.
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We then set a limit on the essential load that can be placed on the injured tissue/structure in context of the patient’s function/s to balance the risk of reinjury/healing and the patient’s essential function(work or sports).
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We identify other structures implicated that are not necessarily acutely injured, but have undergone adaptive changes and reduce their load.
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As the patient heals we then increase load through exercise to maximise healing and remodelling of tissue.
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As further healing occurs and the patient is back to near normal function we further increase load to illicit strength/hypertrophy changes to match the patient’s load tolerance to the load they wish or need to impose on their bodies. Thereby preventing injury from the patient’s day to day load demands.
This is a short explanation of how I think about load in relation to a patient’s injury, pain, function and then rehabilitation. I will expand on how physios apply this load management more specifically in terms of diagnosis, symptom reduction, changing or fixing biomechanics and preventing injury in future articles.