Pain tolerance after stroke: The Tromsø study

Background: Stroke lesions might alter pain processing and modulation by affecting the widely distributed network of brain regions involved. We aimed to compare pain tolerance in stroke survivors and stroke-free persons in the general population, with and without chronic pain. Methods: We included all participants of the sixth and seventh wave of the population-based Tromsø Study who had been tested with the cold pressor test (hand in cold water bath, 3°C, maximum time 106 s in the sixth wave and 120 s in the seventh) and who had information on previous stroke status and covariates. Data on stroke status were obtained from the Tromsø Study Cardiovascular Disease Register and the Norwegian Stroke Register. Cox regression models were fitted using stroke prior to study attendance as the independent variable, cold pressor endurance time as time variable and hand withdrawal from cold water as event. Statistical adjustments were made for age, sex, diabetes, hypertension, hyperlipidaemia, body mass index and smoking. Results: In total 21,837 participants were included, 311 of them with previous stroke. Stroke was associated with decreased cold pain tolerance time, with 28% increased hazard of hand withdrawal (hazard ratio [HR] 1.28, 95% CI 1.10–1.50). The effect was similar in participants with (HR 1.28, 95% CI 0.99–1.66) and without chronic pain (HR 1.29, 95% CI 1.04–1.59). Conclusions: Stroke survivors, with and without chronic pain, had lower cold pressor pain tolerance, with possible clinical implications for pain in this group. Significance: We found lower pain tolerance in participants with previous stroke compared to stroke-free participants of a large, population-based study. The association was present both in those with and without chronic pain. The results may warrant increased awareness by health professionals towards pain experienced by stroke patients in response to injuries, diseases and procedures

Consistent pattern between physical activity measures and chronic pain levels: the Tromsø Study 2015-2016

Epidemiological literature on the relationship between physical activity and chronic pain is scarce and inconsistent. Hence, our aim was to assess the relationship applying comprehensive methodology, including self-reported and accelerometer measures of physical activity and different severity levels of chronic pain. We used data from the Tromsø Study (2015-2016). All residents in the municipality, aged 40 years and older were invited to participate (n=32,591, 51% women). A total of 21,083 (53% women) reported on questionnaires. Additionally, 6,778 participants (54% women) were invited to wear accelerometers (6,125 with complete measurements). Our exposure measures were self-reported leisure time physical activity, exercise frequency, duration and intensity and two accelerometer-measures (steps per day and minutes of moderate to vigorous physical activity per day). Outcome measurements were chronic pain and moderate-to-severe chronic pain. We used Poisson regression to estimate chronic pain prevalence and prevalence ratios for each physical activity measure, with adjustments for sex, age, education level, smoking history, and occupational physical activity. Our main analyses showed an inverse dose-response relationships between all physical activity measures and both severity measures of chronic pain, except that the dose-response relationship with exercise duration was only found for moderate-to-severe pain. All findings were stronger for the moderate-to-severe pain outcomes than for chronic pain. Robustness analyses gave similar results as the main analyses. We conclude that an inverse dose-response association between physical activity and chronic pain is consistent across measures. To summarize, higher levels of physical activity is associated with less chronic pain and moderate-to-severe chronic pain

Factors associated with non-completion of and scores on physical capability tests in health surveys: The North Health in Intellectual Disability Study

Background - This study investigated the completion rates, scores and factors associated with non-completion and low scores on physical capability tests in a health survey administered to adults with intellectual disabilities. Method - Assessment comprised body mass index (BMI), the Short Physical Performance Battery (SPPB), the timed up-and-go (TUG) test, the one-legged stance (OLS) test; and gross motor, communication and behavioural functioning tests. Results - The completion rates among 93 participants (aged 17–78) were 46% for the SPPB, 42% for the TUG, and 31% for the OLS. More severe intellectual disability (OR = 3.12, p  Conclusions - Including physical capability tests in health surveys among adults with intellectual disabilities is important to monitor functional status and guide prevention strategies

Relationships between physical activity and chronic pain: The role of endogenous pain sensitivity - A population-based perspective: The Tromsø Study

Background and aims: Chronic pain is a major global health concern, yet causal mechanisms are not well understood. Physical activity is popular as prevention and treatment, possibly acting through a positive effect on endogenous pain modulation. This has not been examined in the general population. Materials and methods: We used data from the sixth and seventh surveys of the populationbased Tromsø Study (Tromsø6 and Tromsø7, respectively) to perform cross-sectional and longitudinal analyses of the association between physical activity and pain tolerance. We also performed counter-factual mediation analyses to assess the direct effect of physical activity on chronic pain types, and any potential indirect effects on chronic pain mediated through the effect of physical activity on pain tolerance. Results and conclusions: This thesis found evidence supporting higher habitual PA in leisure time, and higher exercise intensity and duration, to be associated with higher coldpain tolerance. This association appeared to be dose-response shaped in leisure-time PA. The same was not seen in accelerometer-assessed PA. Leisure-time PA relationships appeared to be stable when measured in the same individuals at multiple time-points, and more PA over time was related to higher pain tolerance compared to being less active. There were indications that direction of PA change matters. However, PA did not appear to counteract an overall drop in pain tolerance over time. Effect estimates appeared in general to be slightly larger for men than women. Higher PA levels were associated with lower risk of moderateto- severe chronic pain types. For such chronic pain types, a small part of this effect was mediated through an effect on pain tolerance, suggesting pain tolerance might have a mechanistic role in the effect of PA on chronic pain. The clinical significance of this indirect effect is unclear.Bakgrunn og mål: Kronisk smerte er en betydelig global helseutfordring, men årsaksmekanismene er ikke godt forstått. Fysisk aktivitet brukes ofte i forebygging og behandling, og virker muligens gjennom en positiv effekt på endogen smertemodulering. Dette er ikke undersøkt i den generelle befolkningen. Materialer og metoder: Vi brukte data fra den sjette og syvende undersøkelsen av den befolkningsbaserte Tromsøundersøkelsen (henholdsvis Tromsø6 og Tromsø7) for å utføre tverrsnitts- og longitudinelle analyser av sammenhengen mellom fysisk aktivitet og smertetoleranse. Vi utførte også kontrafaktiske medieringsanalyser for å vurdere den direkte effekten av fysisk aktivitet på forskjellige typer kroniske smerter, og mulige indirekte effekter på kroniske smerter som formidles gjennom effekten av fysisk aktivitet på smertetoleranse. Resultater og konklusjoner: Denne avhandlingen fant bevis som støtter at høyere vanemessig fysisk aktivitet i fritiden, og høyere intensitet og varighet av trening, er assosiert med høyere kuldesmerte-toleranse. Denne sammenhengen så ut til å ha en dose-respons-form for fysisk aktivitet i fritiden. Vi fant ikke tilsvarende resultater for akselerometermålt fysisk aktivitet. Assosiasjonene med fysisk aktivitet i fritiden så ut til å være stabile når de ble målt i de samme individene ved flere tidspunkter, og mer fysisk aktivitet over tid var relatert til høyere smertetoleranse sammenlignet med å være mindre aktiv. Det var indikasjoner på at retningen av endring i fysisk aktivitet har betydning. Det så ikke ut til at fysisk aktivitet motvirket en generell nedgang i smertetoleranse over tid. Effektestimatene generelt så ut til å være litt større for menn enn for kvinner. Høyere nivåer av fysisk aktivitet var assosiert med lavere risiko moderate-til-alvorlige typer kroniske smerter. For slike typer kroniske smerter ble en liten del av denne effekten formidlet gjennom en effekt på smertetoleranse, noe som antyder at smertetoleranse kan ha en mekanistisk rolle i effekten av fysisk aktivitet på kroniske smerter. Den kliniske betydningen av denne indirekte effekten er uklar

The incidence and prevalence of Chronic Fatigue Syndrome, Back Pain of unknown origin, Fibromyalgia, and Myalgia in Norwegian women, and their association to physical activity. A prospective cohort study of material from the Norwegian Women and Cancer (NOWAC) study.

Background: Musculoskeletal disorders (MSDs) appear relatively frequent and are costly for society each year, yet they are poorly understood. Four commonly occurring MSDs are Chronic Fatigue Syndrome (CFS), Back Pain (BP) of unknown origin, Fibromyalgia (FM), and muscle pain/Myalgia. There are few Norwegian epidemiologic data on these four outcomes. Physical activity (PA) has been internationally recognized as having a protective effect against chronic disease. The association between PA and these four outcomes is not well understood and the main aim of this study was to investigate this relationship in a large prospective cohort of Norwegian women. Methods: Self-reported data were gathered from 76 367 women in the nationally representative cohort study the Norwegian Women and Cancer study. Data were gathered on total amount of PA at enrolment and of the four outcome conditions during follow-up, in addition to covariate information. We calculated incidence rate and total prevalence. The association between PA and the four outcomes was assessed using multivariate logistic regression analysis. Prevalent cases were excluded from logistic regression analysis. PA was assessed for trend and as a categorical variable. Results: Incidence densities per 100 000 person years were calculated to be as follows: CFS 411, BP 1268, FM 287, and myalgia 1509. Total prevalence was found to be 2.58% for CFS, 13.65% for BP, 5.02% for FM, and 17.87% for myalgia. These were comparable to age-standardized rates for the corresponding Norwegian female population. There was a significant trend (p < 0.001) that increasing levels of PA were associated with a reduced risk CFS, BP and FM. Compared to moderate PA level, very low levels of PA was significantly associated with increased risk of CFS (OR 1.61 (CI 1.38-1.88)), BP (OR 1.17(CI 1.04-1.31)), and FM (OR 1.30(CI 1.07-1.58)). For CFS, PA levels low (OR 1.31 (CI 1.19-1.44)) and very high (OR 1.18 (CI 1.01-1.38)) were also associated with an increased risk of PA. The results showed no significant associations between PA and mylagia. Conclusion: Our study found nationally representative data for incidence and prevalence of CFS, BP, FM, and myalgia in Norwegian women. When compared to moderate levels of total PA, very low PA was associated with an increased risk of CFS, BP, and FM. Low and very high levels of PA were associated with an increased risk of CFS. More studies are needed to confirm the incidence for these outcomes in the Norwegian population, and to investigate the association between these and different types of PA

Longitudinal relationships between habitual physical activity and pain tolerance in the general population.

Physical activity (PA) might influence the risk or progression of chronic pain through pain tolerance. Hence, we aimed to assess whether habitual leisure-time PA level and PA change affects pain tolerance longitudinally in the population. Our sample (n = 10,732; 51% women) was gathered from the sixth (Tromsø6, 2007-08) and seventh (Tromsø7, 2015-16) waves of the prospective population-based Tromsø Study, Norway. Level of leisure-time PA (sedentary, light, moderate, or vigorous) was derived from questionnaires; experimental pain tolerance was measured by the cold-pressor test (CPT). We used ordinary, and multiple-adjusted mixed, Tobit regression to assess 1) the effect of longitudinal PA change on CPT tolerance at follow-up, and 2) whether a change in pain tolerance over time varied with level of LTPA. We found that participants with high consistent PA levels over the two surveys (Tromsø6 and Tromsø7) had significantly higher tolerance than those staying sedentary (20.4 s. (95% CI: 13.7, 27.1)). Repeated measurements show that light (6.7 s. (CI 3.4, 10.0)), moderate (CI 14.1 s. (9.9, 18.3)), and vigorous (16.3 s. (CI 6.0, 26.5)) PA groups had higher pain tolerance than sedentary, with non-significant interaction showed slightly falling effects of PA over time. In conclusion, being physically active at either of two time points measured 7-8 years apart was associated with higher pain tolerance compared to being sedentary at both time-points. Pain tolerance increased with higher total activity levels, and more for those who increased their activity level during follow-up. This indicates that not only total PA amount matters but also the direction of change. PA did not significantly moderate pain tolerance change over time, though estimates suggested a slightly falling effect possibly due to ageing. These results support increased PA levels as a possible non-pharmacological pathway towards reducing or preventing chronic pain

Physical activity and cold pain tolerance in the general population

Background The relationship between habitual physical activity (PA) and experimental pain tolerance has been investigated in small samples of young, healthy and/or single‐sex volunteers. We used a large, population‐based sample to assess this relationship in men and women with and without chronic pain. Methods We used data from the sixth and seventh Tromsø Study surveys (2007–2008; 2015–2016), with assessed pain tolerance of participants with the cold pressor test (CPT: dominant hand in circulating cold water at 3°C, maximum test time 106 s), and self‐reported total amount of habitual PA in leisure time (n = 19,087), exercise frequency (n = 19,388), exercise intensity (n = 18,393) and exercise duration (n = 18,343). A sub‐sample had PA measured by accelerometers (n = 4,922). We used Cox regression to compare CPT tolerance times between self‐reported PA levels. For accelerometer‐measured PA, we estimated hazard ratios for average daily activity counts, and for average daily minutes of moderate‐to‐vigorous PA done in bouts lasting 10 min or more. Models were tested for PA‐sex, and PA‐chronic pain and PA‐moderate‐to‐severe chronic pain interactions. Results Leisure‐time PA, exercise intensity and exercise duration were positively associated with CPT tolerance (p < .001; p = .011; p < .001). More PA was associated with higher CPT tolerance. At high levels of leisure‐time PA and exercise intensity, men had a significantly higher CPT tolerance than women. Accelerometer‐measured PA was not associated with CPT tolerance. Conclusions This study is one of the first to show that higher self‐reported habitual PA was connected to higher experimental pain tolerance in a population‐based sample, especially for men. This was not found for accelerometer‐measured PA. Significance This study finds that higher level of self‐reported leisure‐time physical activity is associated with increased cold pressor pain tolerance in a large population‐based sample. Though present in both sexes, the association is strongest among men. Despite the robust dose–response relationship between pain tolerance and self‐reported activity level, no such relationship was found for accelerometer‐measured activity, reflecting a possible discrepancy in the aspect of physical activity measured. Though the study design does not permit causal conclusions, the findings suggest that increasing physical activity may increase pain tolerance in the general population

Consistent pattern between physical activity measures and chronic pain levels: the Tromsø Study 2015-2016

Epidemiological literature on the relationship between physical activity and chronic pain is scarce and inconsistent. Hence, our aim was to assess the relationship applying comprehensive methodology, including self-reported and accelerometer measures of physical activity and different severity levels of chronic pain. We used data from the Tromsø Study (2015-2016). All residents in the municipality, aged 40 years and older were invited to participate (n=32,591, 51% women). A total of 21,083 (53% women) reported on questionnaires. Additionally, 6,778 participants (54% women) were invited to wear accelerometers (6,125 with complete measurements). Our exposure measures were self-reported leisure time physical activity, exercise frequency, duration and intensity and two accelerometer-measures (steps per day and minutes of moderate to vigorous physical activity per day). Outcome measurements were chronic pain and moderate-to-severe chronic pain. We used Poisson regression to estimate chronic pain prevalence and prevalence ratios for each physical activity measure, with adjustments for sex, age, education level, smoking history, and occupational physical activity. Our main analyses showed an inverse dose-response relationships between all physical activity measures and both severity measures of chronic pain, except that the dose-response relationship with exercise duration was only found for moderate-to-severe pain. All findings were stronger for the moderate-to-severe pain outcomes than for chronic pain. Robustness analyses gave similar results as the main analyses. We conclude that an inverse dose-response association between physical activity and chronic pain is consistent across measures. To summarize, higher levels of physical activity is associated with less chronic pain and moderate-to-severe chronic pain