Can Stretching Increase Your Tolerance to Pain?

Analysis: Stretching has long been believed to provide pain relief, but is rarely directly associated with pain relief

By Hugo Massé-Alarie, University of Laval

To stretch or not to stretch? Should you do it before or after exercise? Does it prevent or heal injuries? Stretching is always a hot topic. While it is effective in improving flexibility, its usefulness in reducing pain has been questioned.

Back pain is one of the most common health problems in our society. It can affect up to 80% of the population at least once in their lifetime. Many patients do not improve after treatment. What makes treatments work or not? Answering this question could improve the quality of life of millions of people.

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From RTÉ Brainstorm, everything you need to know about managing back pain

Healthcare professionals, including physical therapists, often prescribe exercises, such as stretching, to reduce pain. Stretching has long been known to provide pain relief by increasing range of motion and decreasing muscle tone, giving the impression of less pain.

However, this perceived pain relief is rarely directly associated with pain relief. In fact, a recent study showed that increased flexibility was actually associated with a greater tolerance to pain, which occurs during stretching. It’s possible that stretching actually affects pain perception by activating the areas in our central nervous system that modulate pain.

I am a professor of physiotherapy at Laval University and a researcher at Cirris, the university’s center for interdisciplinary research in rehabilitation and social inclusion. Together with students from Laval University and McGill University, I just published new research on the effect of stretching on pain sensitivity: “Stretch-induced hypoalgesia: a pilot study” in the scientific journal Scandinavian Journal of Pain

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From RTÉ Radio 1’s Today With Claire Byrne, Chartered Physiotherapist Jenny Brannigan Discusses Back Pain

For the study, we recruited 22 healthy adults who did not suffer from back pain. Each participant was asked to perform a stretch of the lumbar region (lower back), followed by a stretch of the forearm muscles. The participants were instructed to hold each stretch for three minutes to produce a moderate stretch sensation.

Stretching Causes Hypoalgesia

Before and after each exercise, we measured the pain sensitivity threshold for a muscle of the lower back (lumbar erectors) and a muscle of the forearm (wrist flexors) using an algometer.

An algometer is a measuring instrument equipped with a sensor that calculates the pressure needed to produce a sensation called a pain threshold. In this way we can measure the modulation of pain sensitivity, or the change that stretching has on a pain threshold.

A man with a back puts his hand on the lumbar region.
Stretching the back may not be beneficial for everyone who suffers from back pain. Photo: Shutterstock

We calculated the modulation for each stretch on the stretched area and on an area far from the stretched muscles. A change recorded in an area distant from the stretch could indicate that the areas of the central nervous system that include pain relief were activated and that the stretch therefore had a systemic effect.

We saw that both stretches caused hypoalgesia, an increase in the pain sensitivity threshold. In other words, after the participants performed the stretching exercises, the researcher had to apply more pressure to induce pain.

After wrist extension, stretch-induced hypoalgesia was confined to the stretched area itself, while after flexion of the back, hypoalgesia was also present at a distance from the stretched area (the forearm).

Does the brain play a role?

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From RTÉ Brainstorm, our thoughts about stress, anxiety and worry can make us more prone to back pain and less likely to recover from it

Stretching isn’t the only type of exercise that causes hypoalgesia. Several studies have shown that aerobic exercise and exercises involving sustained muscle contractions also cause hypoalgesia.

These forms of exercise have received much more attention from the scientific community than stretching, with some groups of researchers trying to determine which mechanisms are at work. For example, it has been suggested that exercise-induced hypoalgesia involves the activation of — and interaction between — the opioid and endocannabinoid systems, which control pain.

In a recent review or study, the authors suggested that exercise-induced hypoalgesia could be explained by the unpleasant and sometimes even painful effect of these exercises. Indeed, we know that activating nociceptors (pain receptors) induces hypoalgesia by activating systems that modulate pain, including opioids.

Stretching the back may not be beneficial for everyone who suffers from back pain

For example, holding a hand in a bucket filled with cold water causes an intense pain that causes systemic hypoalgesia. It is possible that similar mechanisms could explain our results, as stretching produces a feeling that is sometimes unpleasant and even painful.

The remote control, and thus possible systemic effects, were only present after straightening the back. We believe that stretching the back may involve stretching a greater mass of structures (muscles, ligaments, tendons, skin) than stretching the wrist, and could therefore have a greater effect. These hypotheses should be tested in future studies.

Stretching is not a miracle cure

The immediate benefits of stretching in people with back pain can be explained by the fact that areas in the body involved in pain modulation were stimulated. However, many people with chronic back pain benefit less from the hypoalgesia usually caused by exercise. This could be explained by differences in the functioning of regions of the central nervous system involved in pain management.

Stretching the back may not be beneficial for everyone who suffers from back pain. Severe back pain that persists over time is usually multifactorial, so general treatment by a health care professional, such as a physical therapist, may be necessary to reduce or control the pain. Stretching is just one of the available treatment tools to improve one’s health condition and it is not a panacea!The conversation

Hugo Massé-Alarie is Assistant Professor of Physiotherapy at the Université Laval. This article was originally published by The Conversation.


The views expressed here are those of the author and do not represent or reflect the views of RTÉ


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