Load/Load Capacity
Load: “A burden or weight that must be carried, or that rests on an individual.” This can be a physical load, expressed in weight (kg), but it can equally be a mental load. When the load is mental, it can no longer be expressed in a numerical value – in that case it is the psychological pressure being placed on an individual.
Load capacity: this is the load that an individual, or part of the individual, is able to carry. Again, this can apply at both the mental and the physical level.
Example 1: the load capacity of a joint might be roughly 40 kg. This means the load the joint can bear is less than or equal to 40 kg. If a person – through excess body weight, for instance – places more than 40 kg on the joint, overload occurs: the joint is being asked to bear a greater load than its capacity allows.
Example 2: a person can carry a certain mental load. In daily life this load is usually low, but certain events can suddenly push it much higher – a distressing event in the person's surroundings, for example. At such a moment, the person's load capacity may drop sharply precisely because an already high load is resting on them. If this load becomes too great, it exceeds the person's load capacity, and the result can be a state of overstrain or burnout.
The physiotherapeutic relevance of load/load capacity: within physiotherapy, load and load capacity must always be taken into account. Patients who come to a physiotherapist almost always have a disturbed balance between the two. The physiotherapist therefore has to carefully judge the load placed on a patient during treatment: not too low, or no result will come from the treatment, but not too high either, since that will only aggravate the complaint. Load and load capacity also play a major role in defining the goal of treatment. A physiotherapist can help a patient either by reducing the load, or by increasing the load capacity.
In the first approach, the therapist addresses whatever is loading the patient. This can involve all kinds of factors – the patient's work environment, excess weight, posture, and so on.
In the second approach, the therapist addresses the patient's load capacity itself. This can be done by training the patient so that they can tolerate a higher load – the patient effectively becomes able to carry more than before.
You could compare treatment to a set of scales, with load on one side and load capacity on the other. On these scales, the load should never outweigh the load capacity. If it does, the physiotherapist can resolve the difference by letting the load decrease on one side and/or the load capacity increase a little on the other.