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1st Jun

2019

Keys to Rehabilitation Exercise Success: Dosage and Timing

I can recall a lecture by an esteemed international manual physical therapist several decades ago, who stated: “Exercise in rehabilitation can be very good, but it can also be very bad!” At first, this seemed to be a curious statement, but I came to fully understand what he meant.

Rehabilitation exercise is a powerful tool, which can enhance healing, by supplying oxygen and nutrients, removing waste products, decreasing inflammation, decreasing painful muscle guarding and tightness, improving circulation and stimulating growth of new capillaries, lubricating joints, and by promoting increased strength of tissues such as ligaments, tendons, fascia and bone. It can also promote improved coordination and position sense, increase muscular endurance, strength and power, as well as reduce perception of pain. Other obvious benefits that I will not cover here, are the positive effects on cardiorespiratory and general health.

But these benefits come only if the exercises are performed with correct dosage and timing.

With timing, I’m referring to how each stage of a person’s healing and rehabilitation requires a different dosage of exercise, to have the desired effect, and to not aggravate the condition.

This is closely tied to what we call tissue irritability, which is a measure of tissue inflammation or sensitivity. It also has to do with the natural healing curve of the tissues, which depends on the severity of the injury or condition.

The wrong timing of exercise choices or intensity, can easily worsen a person’s condition if too aggressive, or lead to insufficient recovery if not progressed enough.

Dosage of exercise is also essential, and includes variables such as positioning of the injured or painful area, direction and range of movement, speed of movement, number of repetitions performed, amount of rest between repetitions and between sets of exercise and between exercise sessions, resistance, and complexity of the movement.

All these variables can produce a very different physiological effect, and must be chosen wisely. As a condition improves, the variables are changed, to promote new required qualities, when timed correctly.

For example, a person with a very painful and irritable low back or hip condition at first may need to do exercises without putting weight on the joints, slowly with small movements only in painfree directions, with sets of 25-40 repetitions and no or minimal resistance, and 40-45 seconds rest between sets of exercise, performed daily or multiple times per day.

Later on, the same person may be able to do more difficult standing exercises, with faster movements with gradually progressed resistance, until movements are done in functional complex patterns, with 12-20 repetitions to significant fatigue, and 1 1/2 – 2 minutes of rest between sets of exercise, 3 times a week. By now, we more significantly improve the tissues’ tolerance to strain with activities, to also prevent recurrence of injury or pain, and develop needed joint stability. Again, correct timing of progressions here is important. Athletes and over motivated individuals tend to progress too fast, and experience flare-ups and set-backs.

But such progressions also depend on the health of the tissues to begin with. As an example, a person with advanced osteoarthritis of his or her knees or hips would not be progressed to a more advanced stage with much loading on the joints, as this would exceed the joints’ tolerance to strain and compression and create increased pain and irritation, and accelerate the joint degeneration. Instead, here lower intensity and higher repetition exercise, and non-weight bearing joint lubrication exercise such as stationary bicycle exercise with no or minimal tension, is the most effective, to reduce pain and improve function.

The prescription of well timed specific exercise dosage and progressions can be a challenge to get right, especially for those lacking many years of experience, but it often determines whether an exercise program will be effective or not.

Another example of correct/incorrect dosage and timing is why and when to include stretching. This goes both for range of motion stretching of joint capsules and ligaments, and to muscle/fascia stretching. A full stretch which is held for some time produces increased strain on the tissues, and can create increased mobility and flexibility.

Whereas this is often appropriate later in the rehabilitation program, or when there is very little tissue irritation, it is not appropriate at other times. This is why:

A painful condition results in a reflex via our nervous system to make certain muscles contract. We call that muscle guarding, which often feels like a painful tight muscle. If that muscle is given a sustained stretch, the stretch reflex in the muscle can get activated, producing even more muscle tension, tightness and pain. This condition is best treated with soft tissue mobilization, joint mobilization/manipulation and light dynamic (with movement) exercise.

Other examples where stretching would be inappropriate, are a strained or partially torn muscle (stretch would commonly delay healing), an irritated tendon (tendinitis/tendinopathy) or an acutely painful frozen shoulder. Stretching in these cases almost certainly would exceed the tension tolerance of these tissues, and result in increased irritation and pain.

This is an example where it is not the exercise itself that matters, but the timing of when it is being applied.

Most people probably think that these principles (and there are many more) of exercise dosage and timing are well understood in the medical and health care community, and even by fitness trainers. Unfortunately they are not. Therefore, it is always best to get help from the professionals who have special training and expertise in rehabilitation exercise, such as Residency and Fellowship trained Orthopedic Manual Physical Therapists.

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