Long-term, health-enhancing physical activity is associated with reduction of pain but not pain sensitivity or improved exercise-induced hypoalgesia in persons with rheumatoid arthritis

Abstract

BackgroundWe aimed to evaluate the 1-year and 2-year outcome of a health-enhancing physical activity (HEPA) support program on global pain, pressure pain sensitivity, and exercise-induced segmental and plurisegmental hypoalgesia (EIH) in persons with rheumatoid arthritis (RA).MethodsThirty participants (27 women and 3 men) were recruited from a larger intervention cohort that engaged in strength training and moderate-intensity aerobic activity. Assessments were performed before the HEPA intervention and at 1-year and 2-year follow-ups. Global pain was assessed on a visual analogue scale (0–100). Pressure pain thresholds (PPTs) and suprathreshold pressure pain at rest corresponding to 4/10 (medium pain) (SP4) and 7/10 (strong pain) (SP7) on Borg CR 10 scale were assessed by algometry. In a subsample (n = 21), segmental and plurisegmental EIH were assessed during standardized submaximal static contraction (30% of the individual maximum), by algometry, alternately at the contracting right M. quadriceps and the resting left M. deltoideus.ResultsGlobal pain decreased from before the intervention to 2-year follow-up (median 11 to median 6, P = 0.040). PPTs and SP4 pressure pain at rest did not change from before the intervention to 2-year follow-up, while SP7 decreased from mean 647 kPa to mean 560 kPa (P = 0.006). Segmental EIH during static muscle contraction increased from the assessment before the intervention (from mean 1.02 to mean 1.42, P = 0.001), as did plurisegmental EIH (from mean 0.87 to mean 1.41, P <0.001). There were no statistically significant changes in segmental or plurisegmental EIH from before the intervention to 2-year follow-up.ConclusionParticipation in a long-term HEPA support program was associated with reduced global pain, whereas pressure pain sensitivity at rest was not reduced and EIH did not change. Thus, our results do not favor the hypothesis that long-term HEPA reduces pain by improving descending pain inhibition in persons with RA.Trial registrationISRCTN25539102, ISRCTN registry, date assigned March 4, 2011. The trial was retrospectively registered.

Pretreatment Exercise-induced Hypoalgesia is Associated With Change in Pain and Function After Standardized Exercise Therapy in Painful Knee Osteoarthritis

“…The current study was unable to demonstrate improvement in EIH after ET. This finding is in line with previous follow-up studies on ET or surgery in KOA 26,41 and RA 67 patients, indicating that analgesic response of ET in pain patients is more complicated than just improvement EIH, which has also recently been argued in a review by Sluka et al 14 suggesting that other pain modulatory mechanisms must be investigated to explain the analgesic effect of exercise programs. Pre-clinical trials have demonstrated changes after vigorous exercise programs in brainstem areas such as the rostral ventromedial medulla (RVM) and periaqueductal gray (PAG), possibly involved in EIH mechanisms 13,14 .…”

“…A hypoalgesic EIH response has been reported in patients with KOA 41 , RA 67 , chronic low back pain 36 , chronic shoulder pain 35 and chronic unspecific musculoskeletal pain 68 , although a hyperalgesic EIH response has also been reported in subgroups of KOA patients 26,31,33 . Furthermore, lower EIH has been reported in physically inactive individuals compared with physically active people 69,70 indicating that exercise or an active lifestyle may improve EIH.…”

Effects of a two-year health-enhancing physical activity program on skeletal muscle protein profiles in people with rheumatoid arthritis

“…Therefore, our results do not support the hypothesis that improved mitochondrial respiratory capacity and decreased lipid accumulation in the muscle tissues due to physical activity lead to decreased pain sensitivity. On the other hand, our results tally the previous study that demonstrated that, in people with RA, the HEPA program improved clinical outcome and decreased global pain intensity, but had no positive effect on pain sensitivity 16 .…”

“…A two-year program of Physical Activity in RA (PARA) 2010 was designed to investigate its feasibility and to study changes in self-reported variables, physical capacity measurements, in ammation, pain modulation and cardiovascular risk 11 . Positive changes during the two-year study period were observed for HEPA participants concerning symptoms and physical capacity [12][13] and cardiovascular risk factors [14][15] , while pain modulation did not change 16 . In this context we performed a pilot study with focus on protein adaptations in muscle tissue in a subgroup of people with RA who consented to repeated muscle biopsies.…”

Sub-maximal endurance exercise does not mediate alterations of somatosensory thresholds

“…QST is considered the clinical gold standard in exploring pain pathologies, therefore we find the assessment of sensory profiles by applying the QST protocol as a methodological strength of our findings 15,16 . Other research groups have used different protocols, such as segmental and plurisegmental exercise-induced hypoalgesia defined as using normalized PPTs during static muscle contractions 23 . This approach is reliable to assess pressure algometry long-term 24 , and can be best understood as a comprehensive tool to assess exercise-induced hypoalgesia.…”