People who are physically active tend to have higher pain tolerance than those who are sedentary, according to new research published in PLOS One. The study highlights the importance of physical activity in increasing pain tolerance and suggests that being physically active or making positive changes in activity level over time can lead to higher pain tolerance.
There is also evidence suggesting that engaging in acute exercise can lead to a temporary reduction in pain sensitivity, known as exercise-induced hypoalgesia. However, limited evidence exists regarding the effects of chronic pain on exercise-induced hypoalgesia and the relationship between habitual physical activity levels and pain sensitivity. Previous studies in this field have primarily focused on small and homogenous samples of young, healthy individuals or single-sex subjects.
“There have been a number of small studies pointing towards our ability to process pain signals as a possible contributing cause of chronic pain, as that often is seen to behave differently in those with chronic pain to those without,” said study author Anders Pedersen Årnes of the University Hospital of North-Norway and The Arctic University of Norway.
“Since physical activity also appears to be a useful tool for preventing and treating chronic pain, we were interested to find out whether this effect on pain tolerance could be one of the mechanisms through which physical activity protects against chronic pain. This study is the first to look at how physical activity relates to pain sensitivity over time in a population-based setting.”
The researchers used data from the Tromsø Study, a large prospective population-based health study conducted in northern Norway. They utilized data from 10,732 individuals who participated in the sixth and seventh surveys, which were conducted approximately 7 to 8 years apart (2007-2008 and 2015-2016, respectively).
The participants self-reported their level of leisure-time physical activity using a modified version of the Saltin and Grimby LTPA Physical Activity Level Scale, which categorized activity levels as sedentary, light, moderate, or vigorous.
Pain tolerance was measured using the cold-pressor test, where participants submerged their hand and wrist in a cold water bath. They were instructed to keep their hand relaxed in the water for as long as possible, up to a maximum tolerance time. The maximum tolerance time during the cold-pressor test was measured at both baseline and follow-up.
The researchers also analyzed data on potential covariates that could confound the relationship between physical activity and pain tolerance. These covariates included factors such as level of education, smoking status, alcohol consumption, self-reported health, occupational physical activity, and chronic pain status.
The researchers found that higher levels of physical activity were associated with increased pain tolerance. Individuals who were physically active at both measurement points, which were about 7-8 years apart, had higher pain tolerance compared to those who were sedentary at both times. Pain tolerance increased with higher levels of overall physical activity, and those who increased their activity level over time showed even greater improvements in pain tolerance.
“The main takeaway is that engaging in habitual physical activity in your leisure time seems to relate to your pain tolerance – the more active you are, the higher your tolerance is likely to be,” Årnes told PsyPost. “Any activity is better than being completely sedentary. Secondly, there were indications that both total amount of physical activity over time, as well as the direction of change in activity level over time matters to how high your pain tolerance is, so making a positive change is probably for the better. All this might lower the risk of experiencing chronic pain.”
The researchers also explored potential factors that might influence the relationship between physical activity and pain tolerance, such as sex and chronic pain. They found that sex did not significantly impact the relationship, and chronic pain did not interfere with the positive association between physical activity and pain tolerance in a general population.
“Unexpectedly, already having chronic pain did not seem to diminish the effect of physical activity on pain tolerance, which appeared just as strong for those with pain as for those without,” Årnes explained. “Furthermore, there was no difference between women and men, which was surprising. We expected to see smaller effects for women, but that was not the case here. Finally, we found quite large effects of the most active versus the least active participants; close to 60 seconds average for the sedentary group versus above 80 seconds tolerance for the most active participants. That is sizeable.”
The researchers acknowledge some limitations of their study. The data they used were observational, which means they could not control for all possible factors that could influence the results. More research is needed to fully understand the underlying mechanisms and establish causality.
“To be clear, exposing someone to an experimental stimuli as we did cannot be interpreted as having measured chronic pain,” Årnes explained. “The connection between our pain sensitivity and the mechanisms of chronic pain are not yet fully understood. Chronic pain is an incredibly common and debilitating condition that arises from a vast variety of causes, but yet we do not fully understand what causes pain to persist in this way. However, some theories point towards this individual ability to process pain signals as a possible contributing reason, as that often is seen to behave differently in those with chronic pain.”
“Since physical activity also appears to be a useful tool for preventing and treating chronic pain, we are trying to ascertain whether this effect on pain sensitivity might have something to do with that. The most important part of our project is to investigate if the effect physical activity has on pain tolerance is protecting us against chronic pain. We have just this month submitting a follow-up study, which looks at how physical activity is protecting us from developing chronic pain in part through increasing our tolerance for pain.”
Despite these limitations, the study found that being physically active was associated with higher pain tolerance compared to being sedentary. The findings suggest that being physically active and making positive changes in activity levels could potentially reduce the risk or severity of chronic pain.
“Remember that every bit of activity helps – both regarding pain tolerance and chronic pain! You don’t have to perform as a top-tier athlete to enjoy the benefits of it,” Årnes said.
The study, “Longitudinal relationships between habitual physical activity and pain tolerance in the general population“, was authored by Anders Pedersen Årnes, Christopher Sievert Nielsen, Audun Stubhaug, Mats Kirkeby Fjeld, Aslak Johansen, Bente Morseth, Bjørn Heine Strand, Tom Wilsgaard, and Ólöf Anna Steingrímsdóttir.
