Higher pain sensitivity and lower muscle strength in postmenonpausal women with early rheumatoid arthritis compared with age-matched healthy women – a pilot study

Joint tenderness at 3 months follow-up better predicts long-term pain than baseline characteristics in early rheumatoid arthritis patients

OBJECTIVE

To investigate pain course over time and to identify baseline and 3-month predictors of unacceptable pain with or without low inflammation in early RA.

METHODS

A cohort of 275 patients with early RA, recruited in 2012-2016, was investigated and followed for 2 years. Pain was assessed using a visual analogue scale (VAS; 0-100 mm). Unacceptable pain was defined as VAS pain >40, and low inflammation as CRP <10 mg/l. Baseline and 3-month predictors of unacceptable pain were evaluated using logistic regression analysis.

RESULTS

After 2 years, 32% of patients reported unacceptable pain. Among those, 81% had low inflammation. Unacceptable pain, and unacceptable pain with low inflammation, at 1 and 2 years was significantly associated with several factors at 3 months, but not at baseline. Three-month predictors of these pain states at 1 and 2 years were higher scores for pain, patient global assessment, and the health assessment questionnaire, and more extensive joint tenderness compared with the number of swollen joints. No significant associations were found for objective inflammatory measures.

CONCLUSION

A substantial proportion of patients had unacceptable pain with low inflammation after 2 years. Three months after diagnosis seems to be a good time-point for assessing the risk of long-term pain. The associations between patient reported outcomes and pain, and the lack of association with objective inflammatory measures, supports the uncoupling between pain and inflammation in RA. Having many tender joints, but more limited synovitis, may be predictive of long-term pain despite low inflammation in early RA.

Hand Grip Strength, Osteoporosis, and Quality of Life in Middle-Aged and Older Adults

Background and Objectives: Hand grip strength (HGS) and osteoporosis are known to be closely related to the health condition of the elderly, respectively. Comprehensive studies including adults over middle age were insufficient. This study aimed to investigate the relationship between HGS with osteoporosis and health-related quality of life (HRQoL) in adults aged >40 years. Materials and Methods: This cross-sectional analysis included data from 13,966 people aged >40 years between 2015 to 2018 provided by the Korea National Health and Nutrition Examination Survey. The HGS was divided into strong and weak quartiles, defined as the highest and lowest quartiles, respectively. We used the European Quality of Life Scale-Five dimensions (EQ-5D) for HRQoL. We performed multiple logistic regression and post hoc analysis to confirm the relationship between the four groups and HRQoL. Results: Osteoporotic patients with weak HGS showed the lowest EQ-5D index (0.87 ± 0.01) among all groups and had a significantly impaired HRQoL in all EQ-5D dimensions, at least 1.75 times more than healthy individuals with strong HGS (0.95 ± 0.00). Osteoporotic patients with weak HGS showed, notably, 2.68 times more impaired mobility compared to healthy individuals with strong HGS among all five dimensions of the EQ-5D. In self-care, significant sex differences in impaired HRQoL were observed (males 6.03, 2.23-16.35; females 2.51, 1.70-3.71). Conclusions: Weak HGS and the presence of osteoporosis were associated with low HRQoL, respectively. Middle-aged and older adults with both weak HGS and osteoporosis showed poorer HRQoL compared to healthy middle-aged and older adults. This suggests that HGS is a possible factor for predicting poor HRQoL in adults aged >40 years with or without osteoporosis. It is necessary to assess the risk of low HRQoL by measuring HGS and confirming whether osteoporosis is accompanied in adults over middle age.

Mechanisms of chronic pain in inflammatory rheumatism: the role of descending modulation

ABSTRACT

Persistent pain despite satisfactory disease treatment is frequent in rheumatoid arthritis (RA) and spondyloarthritis (Spa) and may result from specific changes in central pain processing. We assessed these mechanisms further by systematically comparing thermal pain thresholds and conditioned pain modulation (CPM) between patients with active RA or Spa and healthy controls. We included 50 patients with RA and 50 patients with Spa and 100 age-matched and sex-matched controls. Heat and cold pain thresholds (HPT-CPT) were measured on the dominant forearm, and CPM was assessed by applying conditioning stimuli (immersion in a cold-water bath) to one foot and the nondominant hand in 2 successive randomized sequences. Descending pain modulation was assessed as the difference in HPTs (in °C) before and after conditioning. Larger HPT differences (ie, a larger CPM effect) reflected more efficient descending inhibition. Potential associations between changes in CPM and clinical data, including disease activity, pain intensity, and psychological and functional variables, were systematically assessed. Heat pain threshold and cold pain threshold were similar in patients and controls. The mean CPM effect was significantly weaker in patients than that in controls for conditioning applied to either the foot (0.25°C ±2.57 vs 2.79°C ±2.31; P < 0.001) or the nondominant hand (0.57°C ±2.74 vs 2.68°C ±2.12; P < 0.001). The smaller CPM effect in patients was correlated with average pain intensity, but not with disease activity or other clinical characteristics, suggesting a significant pathophysiological role for changes in endogenous pain modulation in the mechanisms of chronic pain associated with inflammatory rheumatism.

Acute effects of exercise on pain symptoms, clinical inflammatory markers and inflammatory cytokines in people with rheumatoid arthritis: a systematic literature review

Background

Exercise is advocated in the treatment of rheumatoid arthritis (RA). However, uncertainty around the acute effects of exercise on pain and inflammation may be stopping people with RA from exercising more regularly.

Objectives

To determine the acute effects of exercise on pain symptoms, clinical inflammatory markers, and inflammatory cytokines in RA.

Design

A systematic review of the literature.

Data sources and methods

Five databases were searched (PubMed, Cochrane Library, CINAHL, Scopus and SPORTDiscus); inclusion criteria were studies with acute exercise, a definite diagnosis of RA and disease characteristics assessed by clinical function (i.e., disease activity score, health assessment questionnaire and self-reported pain), clinical markers associated with inflammation (i.e., c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)), and inflammatory cytokines (i.e., interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α)).

Results

From a total of 1544 articles, initial screening and full text assessment left 11 studies meeting the inclusion criteria. A total of 274 people were included in the studies (RA = 186; control = 88). Acute bouts of aerobic, resistance, and combined aerobic and resistance exercise did not appear to exacerbate pain symptoms in people with RA.

Conclusion

Post-exercise responses for pain, clinical inflammatory markers and inflammatory cytokines were not different between people with or without RA. Exercise prescription was variable between studies, which limited between-study comparisons. Therefore, future investigations in people with RA are warranted, which combine different exercise modes and intensities to examine acute effects on pain symptoms and inflammatory markers.

Registration

The PROSPERO international prospective register of systematic reviews - CRD42018091155.

Distinct aberrations in cerebral pain processing differentiating patients with fibromyalgia from patients with rheumatoid arthritis

ABSTRACT

The current study used functional magnetic resonance imaging to directly compare disease-relevant cerebral pain processing in well-characterized patient cohorts of fibromyalgia (FM, nociplastic pain) and rheumatoid arthritis (RA, nociceptive pain). Secondary aims were to identify pain-related cerebral alterations related to the severity of clinical symptoms such as pain intensity, depression, and anxiety. Twenty-six patients with FM (without RA-comorbidity) and 31 patients with RA (without FM-comorbidity) underwent functional magnetic resonance imaging while stimulated with subjectively calibrated painful pressures corresponding to a pain sensation of 50 mm on a 100-mm visual analogue scale. Stimulation sites were at the most inflamed proximal interphalangeal joint in the left hand in patients with RA and the left thumbnail in patients with FM, 2 sites that have previously been shown to yield the same brain activation in healthy controls. The current results revealed disease-distinct differences during pain modulation in RA and FM. Specifically, in response to painful stimulation, patients with FM compared to patients with RA exhibited increased brain activation in bilateral inferior parietal lobe (IPL), left inferior frontal gyrus (IFG)/ventrolateral prefrontal cortex (vlPFC) encapsulating left dorsolateral prefrontal cortex, and right IFG/vlPFC. However, patients with RA compared to patients with FM exhibited increased functional connectivity (during painful stimulation) between right and left IPL and sensorimotor network and between left IPL and frontoparietal network. Within the FM group only, anxiety scores positively correlated with pain-related brain activation in left dorsolateral prefrontal cortex and right IFG/vlPFC, which further highlights the complex interaction between affective (ie, anxiety scores) and sensory (ie, cerebral pain processing) dimensions in this patient group.

Predictors of unacceptable pain with and without low inflammation over 5 years in early rheumatoid arthritis-an inception cohort study

Objectives

Pain is a major symptom in patients with rheumatoid arthritis (RA). In early RA, pain is usually due to synovitis, but can also persist despite effective anti-inflammatory treatment. The objective of this study was to investigate the pain course over time and predictors of unacceptable pain and unacceptable pain with low inflammation, in patients with early RA.

Methods

An inception cohort of 232 patients with early RA, recruited in 1995–2005, was followed in a structured programme for 5 years. Pain was assessed using a visual analogue scale (VAS; 0–100). Unacceptable pain was defined as VAS pain > 40 based on the patient acceptable symptom state (PASS) and low inflammation as CRP < 10 mg/l. Baseline predictors of unacceptable pain were evaluated using logistic regression analysis.

Results

Pain improved significantly during the first 6 months, but then remained basically unchanged. Thirty-four per cent of the patients had unacceptable pain 5 years after inclusion. Baseline predictors of unacceptable pain after 5 years were lower swollen joint counts [odds ratio (OR) 0.71 per standard deviation (95% confidence interval (CI) 0.51–0.99)] and higher VAS for pain and global assessment of disease activity. Unacceptable pain with low inflammation after 5 years was negatively associated with anti-CCP antibodies [OR 0.50 (95% CI 0.22–0.98)].

Conclusion

Over one third of the patients had unacceptable pain 5 years after inclusion. Lower swollen joint count was associated with unacceptable pain at 5 years. The results may be explained by the positive effects of treatment on pain related to inflammation. Non-inflammatory long-lasting pain appears to be a greater problem in anti-CCP-negative patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02550-7.

The Association of Psychosocial Factors and Exercise-Induced Hypoalgesia in Healthy People and People With Musculoskeletal Pain: A Systematic Review

BACKGROUND

Exercise, a cornerstone in current treatments for people with musculoskeletal pain, elicits a phenomenon called exercise-induced hypoalgesia (EIH), which may result in reduced pain intensity and/or increased pain thresholds. However, EIH can be impaired in patients with musculoskeletal pain, and psychosocial factors may play a mediating role in EIH.

OBJECTIVE

The aim of this study was to systematically review the scientific literature regarding the association between psychosocial factors and EIH in healthy people and people with musculoskeletal pain.

METHODS

An extensive search in databases including Medline Ovid, Embase, Web of Science, PsycINFO Ovid, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCOhost was carried out. Two reviewers independently carried out study selection, data extraction, and critical appraisal. Included studies analyzed the association or effect of psychosocial factors on EIH in adults with or without musculoskeletal pain.

RESULTS

Nine cross-sectional studies were included, 6 involving healthy people and 4 involving people with musculoskeletal pain; 1 study included both. Overall risk of bias was high. Different types of exercise bouts, psychosocial factors, and/or outcome measures were used across studies. In healthy people and people with musculoskeletal pain, most studies did not find an association between psychosocial factors and EIH. However, 1 study involving musculoskeletal pain and 2 studies with healthy people did find a significant association.

CONCLUSION

Due to poor quality and heterogeneity between studies, no conclusions can be drawn regarding whether psychosocial factors are associated with EIH or not. This review includes recommendations and directions for further research to investigate the role of psychosocial factors on EIH.

The effect of blood flow restriction exercise on exercise-induced hypoalgesia and endogenous opioid and endocannabinoid mechanisms of pain modulation

This study aimed to investigate and compare the magnitude of exercise-induced hypoalgesia (EIH) with low-intensity blood flow restriction (BFR) resistance exercise (RE) at varying pressures to other intensities of resistance exercise and examine endogenous mechanisms of pain reduction. Twelve individuals performed four experimental trials involving unilateral leg press exercise in a randomized crossover design: low-load RE at 30% of one repetition maximum (1RM), high-load RE (70% 1RM), and BFR-RE (30% 1RM) at a low and high pressure. BFR pressure was prescribed relative to limb occlusion pressure at 40% and 80% for the low- and high-pressure trials. Pressure pain thresholds (PPT) were assessed before and 5 min and 24 h following exercise in exercising and nonexercising muscles. Venous blood samples were collected at the same timepoints to determine plasma concentrations of beta-endorphin and 2-arachidonoylglycerol. High-pressure BFR-RE increased PPTs in the exercising limb to a greater extent than all other trials. Comparable systemic EIH effects were observed with HLRE and both BFR-RE trials. PPTs in the exercising limb remained elevated above baseline at 24 h postexercise following both BFR-RE trials. Postexercise plasma beta-endorphin concentration was elevated during the BFR-RE trials. No changes to 2-arachidonoylglycerol concentration were observed. High pressure BFR-RE causes a greater EIH response in the exercising limb that persists for up to 24 h following exercise. The reduction in pain sensitivity with BFR-RE is partly driven by endogenous opioid production of beta-endorphin. BFR-RE should be investigated as a possible pain-modulation tool in individuals with acute and chronic pain.

NEW & NOTEWORTHY High-pressure blood flow restriction (BFR) causes a greater hypoalgesia response in the exercising limb (48%) compared with light and heavy load resistance exercise (10–34%). Performing light load resistance exercise with BFR causes systemic hypoalgesia comparable with heavy load resistance exercise (10–18%). BFR resistance exercise prolonged the exercise-induced hypoalgesia response for 24 h in the exercising limb (15% and 24%, respectively). Activation of endogenous opioid production and a conditioned pain modulation effect partly mediate the relationship between exercise and hypoalgesia.

Exercise-Induced Hypoalgesia in Pain-Free and Chronic Pain Populations: State of the Art and Future Directions

Exercise is considered an important component of effective chronic pain management and it is well-established that long-term exercise training provides pain relief. In healthy, pain-free populations, a single bout of aerobic or resistance exercise typically leads to exercise-induced hypoalgesia (EIH), a generalized reduction in pain and pain sensitivity that occurs during exercise and for some time afterward. In contrast, EIH is more variable in chronic pain populations and is more frequently impaired; with pain and pain sensitivity decreasing, remaining unchanged or, in some cases, even increasing in response to exercise. Pain exacerbation with exercise may be a major barrier to adherence, precipitating a cycle of physical inactivity that can lead to long-term worsening of both pain and disability. To optimize the therapeutic benefits of exercise, it is important to understand how EIH works, why it may be impaired in some people with chronic pain, and how this should be addressed in clinical practice. In this article, we provide an overview of EIH across different chronic pain conditions. We discuss possible biological mechanisms of EIH and the potential influence of sex and psychosocial factors, both in pain-free adults and, where possible, in individuals with chronic pain. The clinical implications of impaired EIH are discussed and recommendations are made for future research, including further exploration of individual differences in EIH, the relationship between exercise dose and EIH, the efficacy of combined treatments and the use of alternative measures to quantify EIH. PERSPECTIVE: This article provides a contemporary review of the acute effects of exercise on pain and pain sensitivity, including in people with chronic pain conditions. Existing findings are critically reviewed, clinical implications are discussed, and recommendations are offered for future research.

Characterization of neuroinflammation and periphery-to-CNS inflammatory cross-talk in patients with disc herniation and degenerative disc disease

The aim of the study was to identify inflammatory cytokines/chemokines associated with neuroinflammation and periphery-to-CNS inflammatory cross-talk in degenerative disc disease (DDD) and lumbar disc herniation (LDH), common causes of low back pain (LBP). A secondary aim was to investigate the associations between cytokines and symptom severity.

METHODS

In total, 40 DDD and 40 LDH patients were recruited from a surgical waiting list, as well as 39 healthy controls (HC) and 40 cerebrospinal fluid (CSF) controls. The subjects completed questionnaires and pressure algometry was performed at the lumbar spine and forearm. The CSF, serum and disc tissues were collected during surgery. Inflammatory mediators TNF, INFg, IL-1b, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13 and MCP1 were analysed by immunoassay (Meso Scale Discovery) and quantitative real-time polymerase chain reaction (qPCR) was used for analysis of IL-6, IL-8, MCP1 and TSPO expression in intervertebral discs (IVDs).

RESULTS

In the LDH group, we found elevated IL-8 concentrations in CSF indicating neuroinflammation, while IL-8 and MCP1 concentrations in serum were lower compared to HC. The IVD expression of IL-6, IL-8 and TSPO was lower in LDH patients compared to DDD. LDH patients had a positive correlation between IL-8 concentrations in CSF and serum and IL-8 in CSF was associated with higher pain intensity and increased spinal pressure pain sensitivity. The MCP1 concentration in serum was associated with higher global pain ratings and increased spinal pressure pain sensitivity, while IL-6 serum concentration correlated with the intensity of the neuropathic pain component (leg pain) in LDH patients. IVD expression of TSPO in LDH patients was associated with increased intensity of back pain. No differences were found in cytokine CSF concentrations between DDD patients and CSF controls, but DDD patients had lower IL-8 and MCP1 serum concentrations than HC. In female DDD patients, IL-8 and MCP1 concentrations in serum were associated with increased intensity of back pain.

CONCLUSION

Our results suggest that neuroinflammation mediated by elevated IL-8 concentrations in CSF and IL-8 mediated periphery-to-CNS inflammatory cross-talk contributes to pain in LDH patients and suggest a link between TSPO expression in discs and low back pain.

Impact of classic massage on the pressure pain threshold- a preliminary study

Background: The pressure pain threshold (PPT) differs by muscle, depends on sex, age, and health status, and alters under the influence of disease. It is interesting to ask how and whether tissue sensitivity changes after the application of therapy. Aim of the study: The purpose of this study was to assess in healthy individuals the pressure sensitivity of muscles in the torso following a classic massage. Material and methods: A measurement of the pressure sensitivity of certain muscles of the back (the latissimus dorsi, the trapezius, and the spinal erector) was performed using an algometer before classic back massage and immediately after the procedure. A classic back massage was given to 60 healthy volunteers aged 20–47 years. The massage lasted 20 minutes and the major techniques were performed on selected superficial and deep muscles of the back. Results: The pressure sensitivity of the muscles decreased after the classic massage. Statistically significant changes were observed in the right (p < 0.001) and left (p = 0.002) spinal erectors; in the transverse part on both sides (p < 0.001), and in the descending part on both sides (p < 0.001) of the trapezius muscle; and in the right (p = 0.008) and left (p = 0.004) of the latissimus dorsi muscle. Conclusions: Classic massage alleviates tissue sensitivity to pressure in healthy individuals. It can be effective in cases of increased resting muscle tone accompanied by increased tissue sensitivity.

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

Background

We 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).

Methods

Thirty 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.

Results

Global 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.

Conclusion

Participation 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 registration

ISRCTN25539102, ISRCTN registry, date assigned March 4, 2011. The trial was retrospectively registered.

High prevalence of widespread pain in women with early rheumatoid arthritis

OBJECTIVES

The aim of the study was to determine the prevalence of widespread pain (WP) in women with early rheumatoid arthritis (RA) and to compare physical function, activity limitations, health-related quality of life, mental distress, and disease activity between women with WP and non-widespread pain (NWP).

METHOD

This cross-sectional study included 102 women with early RA. Participants were provided with self-reported questionnaires quantifying activity limitations, physical activity, pain intensity, health-related quality of life, and fatigue. Hand-grip force, muscle function test of the lower extremities, erythrocyte sedimentation rate, and number of tender and swollen joints were assessed.

RESULTS

One-third (35.9%) of the women fulfilled the American College of Rheumatology criteria for WP 20 months after disease onset. Women with RA + WP had significantly higher 28-joint Disease Activity Score (DAS28) (p = 0.004), number of tender joints (p = 0.001), pain intensity (p < 0.001), fatigue (p < 0.001), Health Assessment Questionnaire score (p < 0.001), and Hospital Anxiety and Depression Scale - Depression (p = 0.001). Furthermore, women with RA + WP showed significantly worse global health (p < 0.001) and physical health (36-item Short Form Health Survey - Physical Component Summary) (p < 0.001). The hand-grip force was found to be significantly reduced (p = 0.001), as was the muscle function of the lower extremities (p < 0.001), for women with RA + WP compared to women with RA + NWP. After adjustment for inflammatory joint disease, the significant differences between the groups remained.

CONCLUSION

A significant group of women with early RA experience WP with a high DAS28 and increased pain intensity level. These women display severe muscle function deficiency in clinical examinations, and report general activity limitations and low psychological and physical health, despite an absence of or low objective signs of inflammation.

Pain sensitivity at rest and during muscle contraction in persons with rheumatoid arthritis: a substudy within the Physical Activity in Rheumatoid Arthritis 2010 study

Background

We aimed to explore pressure pain sensitivity and the function of segmental and plurisegmental exercise-induced hypoalgesia (EIH) in persons with rheumatoid arthritis (RA) compared with healthy control subjects (HC).

Methods

Forty-six participants with RA (43 female, 3 male) and 20 HC (16 female, 4 male) participated in the study. Pressure pain thresholds, suprathreshold pressure pain at rest, and segmental and plurisegmental EIH during standardised submaximal contractions were assessed by algometry. Assessments of EIH were made by performing algometry alternately at the contracting (30% of the individual maximum) right m. quadriceps and the resting left m. deltoideus.

Results

Participants with RA had higher sensitivity to pressure pain (RA, 318 kPa; HC, 487 kPa; p < 0.001), suprathreshold pressure pain 4/10 (RA, 433 kPa; HC, 638 kPa; p = 0.001) and suprathreshold pressure pain 7/10 (RA, 620 kPa; HC, 851 kPa; p = 0.002) than HC. Segmental EIH (RA, 0.99 vs 1.27; p < 0.001; HC, 0.89 vs 1.10; p = 0.016) and plurisegmental EIH (RA, 0.95 vs 1.36; p < 0.001; HC, 0.87 vs 1.31; p < 0.001) increased significantly during static muscle contraction in both groups alike (p > 0.05).

Conclusions

Our results indicate a generally increased pain sensitivity but normal function of EIH among persons with RA and offer one possible explanation for pain reduction observed in this group of patients following clinical exercise programmes.

Trial registration

ISRCTN registry, ISRCTN25539102. Retrospectively registered on 4 March 2011.

Objectively measured physical activity and its influence on physical capacity and clinical parameters in patients with primary Sjögren's syndrome

Objective The objectives of this paper are to objectively measure habitual physical activity levels in patients with primary Sjögren's syndrome (pSS) with mild disease activity and to determine to which extent it may be associated with physical capacity and function and clinical features. Methods In this cross-sectional study, 29 women with pSS were objectively assessed for habitual physical activity levels (using accelerometry) and compared with 20 healthy women (CTRL) frequency-matched for physical activity levels, age, body mass index, and body fat percentage with regard to physical capacity and function, fatigue, depression, pain, and health-related quality of life. Results pSS showed 8.5 min/day of moderate-to-vigorous physical activity (MVPA) when only MVPA accumulated in bouts ≥ 10 min was considered; when considering total MVPA (including bouts < 10 min), average levels were 26.3 min/day, with 62% of pSS patients achieving the recommendation (≥ 21.4 min/day). Moreover, pSS showed lower VO_2peak, lower muscle strength and function, higher fatigue, and poorer health-related quality of life when compared with CTRL ( p < 0.05). These differences (except for aerobic capacity) were sustained even when only individuals achieving the minimum of 21.4 min/day of total MVPA in both groups were compared. Finally, MVPA time was significantly correlated with aerobic conditioning, whereas total counts and sedentary time were associated with lower-body muscle strength and the bodily-pain domain of SF-36 in patients with pSS. Conclusion When compared to physical activity-matched healthy controls, pSS patients showed reduced physical capacity and function, increased fatigue and pain, and reduced health-related quality of life. Except for aerobic conditioning, these differences were sustained when only more physically active participants were compared, indicating that minimum recommended levels of physical activity for the general population may not be sufficient to counteract pSS comorbidities.

Intrinsic Brain Connectivity in Chronic Pain: A Resting-State fMRI Study in Patients with Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is commonly accompanied by pain that is discordant with the degree of peripheral pathology. Very little is known about the cerebral processes involved in pain processing in RA. Here we investigated resting-state brain connectivity associated with prolonged pain in RA.

Methods: 24 RA subjects and 19 matched controls were compared with regard to both behavioral measures of pain perception and resting-resting state fMRI data acquired subsequently to fMRI sessions involving pain stimuli. The resting-state fMRI brain connectivity was investigated using 159 seed regions located in cardinal pain processing brain regions. Additional principal component based multivariate pattern analysis of the whole brain connectivity pattern was carried out in a data driven analysis to localize group differences in functional connectivity.

Results: When RA patients were compared to controls, we observed significantly lower pain resilience for pressure on the affected finger joints (i.e., P50-joint) and an overall heightened level of perceived global pain in RA patients. Relative to controls, RA patients displayed increased brain connectivity predominately for the supplementary motor areas, mid-cingulate cortex, and the primary sensorimotor cortex. Additionally, we observed an increase in brain connectivity between the insula and prefrontal cortex as well as between anterior cingulate cortex and occipital areas for RA patients. None of the group differences in brain connectivity were significantly correlated with behavioral parameters.

Conclusion: Our study provides experimental evidence of increased connectivity between frontal midline regions that are implicated in affective pain processing and bilateral sensorimotor regions in RA patients.