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How exercise can help cure a sore back or knee

Unlikely as it may seem, physical activity is one of the surest cures for a sore back or aching knee.

Christchurch physiotherapist Tracey Pons isn’t suggesting you go for a 10km run to get rid of your chronic lower-back pain – or, as she prefers to call it, persistent pain. But nor should you sit still.

“Chronic has emotional negative baggage in some contexts,” she says.

Pons, who specialises in pain management, says a graded exercise programme can eventually turn your pain switch off. You could, for example, start by doing three gentle 10-minute walks each day, then gradually increase the sessions’ intensity and duration.

She says about a third of people who stick with the programme eventually experience complete pain relief. Most of the others continue to have occasional pain flare-ups – often associated with colder weather – but are pain-free most of the time.

“They might not be climbing Mt Everest, but they will still be able to do some exercise within their tolerance limits.”

A small number continue to experience persistent pain and may need to be referred to a specialist pain physician for further assessment. “There isn’t a miracle cure. For some people, pain persists despite good management and intervention.”

One in five New Zealanders suffers from chronic or persistent pain, with the most common locations being in the lower back, knee, shoulder and neck. The economic costs are huge – about $24 billion a year, according to recent research commissioned by the Australian and New Zealand College of Anaesthetists.

Tracey Pons. Photo/Supplied

In many cases, the pain starts with a minor injury, perhaps after bending to pick something up. However, for reasons we don’t understand, in some people the pain continues long after the tissue has healed. Chronic or persistent pain is defined as pain that is still present beyond the normal tissue-healing time – about 12 weeks.

It is thought to be caused by what is sometimes called central sensitisation, in which the nervous system has gone into a state of high alert and starts responding in a disproportionate way to minor stimuli.

As Pons points out, we need to experience pain to alert us to possible dangers to our body. But sometimes our pain system becomes too sensitive. “We get this massive alarm response when it is actually just a little skink skittering through the grass and not a massive snake.”

With persistent pain, merely bending over can continue to be painful and the pain can start to spread to other parts of the body. The result is a vicious circle, in which fear of pain makes a person move less, their body stiffens, healthy tissue becomes sensitised and pain increases.

In the past, people with persistent pain were told to rest. However, the advice now is to keep active. As Australian pain guru Lorimer Moseley puts it, “Exercise is medicine, motion is lotion”.

There are various theories about why exercise and movement help. As well as building strength and flexibility, they’re also thought to “settle” a sensitive nervous system by releasing endorphins that can also boost mood. Exercising may also reduce the fear, anxiety and catastrophic thinking associated with movement that can in themselves cause more pain.

There’s no exact prescription for how much and what kind of exercise to do. Possibilities include walking, swimming, using an exercycle or cross trainer and doing resistance exercise. The most important thing is to start slowly, then gradually increase both the intensity and duration.

Pons says it’s possible to embark on a graded exercise programme yourself. However, she says it’s good to have a coach such as a physiotherapist to guide you. They can rule out any biomechanical causes of your pain and help you understand the brain mechanisms that cause you to feel pain despite having no tissue damage. They can also help you find minimally painful movements to reduce anxiety associated with physical activity.

Perhaps most importantly, they can help you understand that while exercising may hurt, it won’t cause any damage.

“There are many for whom the pain switch won’t fully disengage following what might have been a trivial injury, but we can reassure them that it’s still safe to move.”

This article was first published in the October 5, 2019 issue of the New Zealand Listener.