Physically active people tend to have higher pain tolerance than those who are sedentary, according to a new study published in Plus one. The study underscores the importance of physical activity in increasing pain tolerance and suggests that physical activity, or positive changes in activity levels over time, may lead to higher pain tolerance.
There is also evidence that acute exercise can result in a transient reduction in pain sensitivity, known as exercise-induced hypoalgesia. However, there is limited evidence on the impact of chronic pain on exercise-induced hypoalgesia and on the association between habitual physical activity and pain sensitivity. Previous studies in this area have mainly focused on small and homogeneous samples of young, healthy, or same-sex subjects.
“There were a number of smaller studies that suggested that our ability to process pain signals could be a possible cause of chronic pain, as it often behaves differently in people with chronic pain than in people without chronic pain,” the study author said Anders Pedersen Årnes of the University Hospital of Northern Norway and the Arctic University of Norway.
“Since physical activity also appears to be a useful tool for preventing and treating chronic pain, we wanted to explore whether this effect on pain tolerance might be one of the mechanisms by which physical activity protects against chronic pain.” This study is the first which examines how physical activity is related 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 used data from 10,732 people who took part in the sixth and seventh surveys, conducted about seven to eight years apart (2007-2008 and 2015-2016, respectively).
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, in which participants immersed 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 compression test was measured both at baseline and at follow-up.
Researchers also analyzed data on potential covariates that could confound the association between physical activity and pain tolerance. These covariates included factors such as educational level, smoking status, alcohol consumption, self-reported health status, occupational physical activity, and chronic pain status.
Researchers found that higher levels of physical activity were associated with increased pain tolerance. People who were physically active at both time points, which were about 7 to 8 years apart, had a higher pain tolerance than those who were sedentary at both time points. Overall pain tolerance increased with increased physical activity, and those who increased their activity level over time showed even greater improvements in pain tolerance.
“The key finding is that engaging in habitual physical activity in your free time appears to be associated with 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. Second, there was evidence that both the total amount of physical activity over time and the direction of change in activity levels over time have an impact on how high your pain tolerance is, so positive change is likely to be for the better. All of this could lower the risk of chronic pain.”
Researchers also looked at possible factors that might affect the link between physical activity and pain tolerance, such as sex and chronic pain. They found that sex did not have a significant impact on the relationship and that chronic pain did not affect the positive association between physical activity and pain tolerance in the general population.
“Unexpectedly, the effect of physical activity on pain tolerance who already had chronic pain did not seem to decrease the effect of physical activity on pain tolerance, which seemed to be as strong in people with pain as in people without pain,” explained Årnes. “Also, there was no difference between women and men, which was surprising. We expected less impact for women, but that wasn’t the case here. Finally, we found fairly large effects between the most active and the least active participants; The average is around 60 seconds for the seated group, while the tolerance is over 80 seconds for the most active participants. That’s significant.”
The researchers acknowledge some limitations of their study. The data they used was observational, meaning they could not control for all possible factors that could affect the results. Further research is needed to fully understand the underlying mechanisms and establish a causal relationship.
“To be clear, when we expose someone like us to an experimental stimulus, it cannot be interpreted as a measurement of chronic pain,” explained Årnes. “The connection between our sensitivity to pain and the mechanisms of chronic pain is not yet fully understood. Chronic pain is an incredibly common and debilitating condition that can result from a variety of causes. Still, we don’t fully understand what causes the pain to persist in this way. However, some theories suggest that this individual ability to process pain signals may be a possible cause, as it often behaves differently in people with chronic pain.”
“Since physical activity also seems to be a useful tool for preventing and treating chronic pain, we are trying to find out whether this effect on pain sensitivity might be related.” The most important part of our project is to investigate whether the effect physical activity on pain tolerance protects us from chronic pain. Just this month, we submitted a follow-up study examining how physical activity protects us from developing chronic pain, in part by increasing our pain tolerance.”
Despite these limitations, the study found that physical activity was associated with higher pain tolerance compared to sedentary work. The results suggest that physical activity and positive changes in activity levels could potentially reduce the risk or severity of chronic pain.
“Remember that every little activity helps – both in terms of pain tolerance and chronic pain! You don’t have to be a top athlete to reap the benefits,” said Årnes.
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 Olöf Anna Steingrímsdóttir.