Reduced pressure pain thresholds in response to exercise in chronic fatigue syndrome but not in chronic low back pain: an experimental study

Central neurobiological effects of physical exercise in individuals with chronic musculoskeletal pain: a systematic review

OBJECTIVE

Primary objectives: to investigate the central neurobiological effects (using MRI) of physical exercise in individuals with chronic pain. Secondary objectives: (1) to investigate the associations between central changes and clinical outcomes and (2) to investigate whether different types and dosages of physical exercise exert different central changes.

DESIGN

Systematic review searching four electronic databases up to September 2018: AMED, CINAHL, Embase and MEDLINE. Two reviewers independently assessed the methodological quality of included studies using the Cochrane Collaboration's Risk of Bias in Non-Randomised Studies-I tool. A standardised extraction table was used for data extraction, which was performed by two reviewers.

INTERVENTIONS

Studies reporting any physical exercise intervention in any chronic musculoskeletal pain condition were included. Eligibility of 4011 records was screened independently by two reviewers, and four studies were included in the review.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome: any brain outcome assessed with any MR technique.

SECONDARY OUTCOMES

any self-reported clinical outcomes, and type and dosage of the exercise intervention.

RESULTS

All four studies had high risk of bias. There was heterogeneity between the brain areas studied and the types of exercise interventions delivered. All studies reported functional MRI changes in various brain areas following an exercise intervention. Insufficient data were available to conduct a meta-analysis or to answer the secondary aims.

CONCLUSIONS

Only a limited number of studies were available and all were at high risk of bias. None of the studies was randomised or included blinded assessment. Exercise may exert effects on brain neurobiology in people with chronic pain. Due to the high risk of bias, future studies should use a randomised study design. Investigation of morphological brain changes could be included.

PROSPERO REGISTRATION NUMBER

CRD42018108179.

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

Physical exercise has been shown to alter sensory functions, such as sensory detection or perceived pain. However, most contributing studies rely on the assessment of single thresholds, and a systematic testing of the sensory system is missing. This randomised, controlled cross-over study aims to determine the sensory phenotype of healthy young participants and to assess if sub-maximal endurance exercise can impact it. We investigated the effects of a single bout of sub-maximal running exercise (30 min at 80% heart rate reserve) compared to a resting control in 20 healthy participants. The sensory profile was assessed applying quantitative sensory testing (QST) according to the protocol of the German Research Network on Neuropathic Pain. QST comprises a broad spectrum of thermal and mechanical detection and pain thresholds. It was applied to the forehead of study participants prior and immediately after the intervention. Time between cross-over sessions was one week. Sub-maximal endurance exercise did not significantly alter thermal or mechanical sensory function (time × group analysis) in terms of detection and pain thresholds. The sensory phenotypes did not indicate any clinically meaningful deviation of sensory function. The alteration of sensory thresholds needs to be carefully interpreted, and only systematic testing allows an improved understanding of mechanism. In this context, sub-maximal endurance exercise is not followed by a change of thermal and mechanical sensory function at the forehead in healthy volunteers.

Pressure pain threshold and temporal summation in adults with episodic and persistent low back pain trajectories: a secondary analysis at baseline and after lumbar manipulation or sham

BACKGROUND

People with chronic low back pain (LBP) typically have increased pain sensitivity compared to healthy controls, however its unknown if pain sensitivity differs based on LBP trajectory at baseline or after manual therapy interventions. We aimed to compare baseline pressure pain threshold (PPT) and temporal summation (TS) between people without LBP, with episodic LBP, and with persistent LBP, and to compare changes over time in PPT and TS after a lumbar spinal manipulation or sham manipulation in those with LBP.

METHODS

Participants were aged 18-59, with or without LBP. Those with LBP were categorised as having either episodic or persistent LBP. PPT and TS were tested at baseline. LBP participants then received a lumbar spinal manipulation or sham, after which PPT and TS were re-tested three times over 30 min. Generalised linear mixed models were used to analyse data.

RESULTS

One hundred participants (49 female) were included and analysed. There were 20 non-LBP participants (mean age 31 yrs), 23 episodic LBP (mean age 35 yrs), and 57 persistent LBP (mean age 37 yrs). There were no significant differences in PPT or TS between groups at baseline. There was a non-significant pattern of lower PPT (higher sensitivity) from the non-LBP group to the persistent LBP group at baseline, and high variability. Changes in PPT and TS after the interventions did not differ between the two LBP groups.

DISCUSSION

We found no differences between people with no LBP, episodic LBP, or persistent LBP in baseline PPT or TS. Changes in PPT and TS following a lumbar manual therapy intervention do not appear to differ between LBP trajectories.

TRIAL REGISTRATION

The trial was prospectively registered with ANZCTR (ACTRN12617001094369).

Convergent and Discriminant Validity of the Serbian Version of the Central Sensitization Inventory

OBJECTIVES

The goal of the present study was to explore additional evidence of validity of the Serbian version of the Central Sensitization Inventory (CSI), a patient-reported outcome measure of symptoms that have been found to be associated with central sensitization (CS). The CSI has been found to be psychometrically sound, and has demonstrated evidence of convergent and discriminant validity in numerous published studies and in multiple languages.

METHODS

CSI data were collected from 399 patients with chronic pain who had various diagnoses and from 146 pain-free controls. In addition, the patient sample completed a battery of validated patient-reported outcome measures of sleep problems, cognitive problems, pain catastrophizing, pain-related fear-avoidance, decreased quality of life, and decreased perception of social support. Six patient subgroups were formed, with presumably different levels of CS (including those with fibromyalgia, multiple pain sites, and localized pain sites).

RESULTS

Significant differences were found in total CSI scores among the controls and patient subgroups. Those with fibromyalgia and multiple pathologies scored highest and the control subjects scored lowest. Other patient-reported CS-related symptom dimensions were significantly correlated with total CSI scores. When the patients were divided into CSI severity subgroups (from subclinical to extreme), the severity of these other symptom dimensions increased with the severity of CSI scores.

CONCLUSIONS

The current study successfully demonstrated additional evidence of the convergent and discriminant validity of the Serbian version of the CSI.

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.

Power of Words: Influence of Preexercise Information on Hypoalgesia after Exercise-Randomized Controlled Trial

PURPOSE

Exercise increases pressure pain thresholds (PPT) in pain-free individuals, known as exercise-induced hypoalgesia (EIH). Positive preexercise information can elicit higher EIH responses, but the effect of positive versus negative preexercise information on EIH is unknown. The primary aim of this randomized controlled trial was to compare EIH at the exercising thigh muscle after an isometric squat exercise between individuals receiving positive versus negative preexercise information about the effect of exercise on pain. Secondary aims were to compare EIH at nonexercising muscles between groups, and to investigate the relationship between participants' expectations and EIH.

METHODS

Eighty-three participants were randomly assigned to brief positive (n = 28), neutral (n = 28) or negative (n = 27) verbal information. The neutral information group was included in the study as a reference group. Pressure pain thresholds at the thigh and trapezius muscles were assessed before and after the intervention (i.e., preexercise information+squat exercise). Expectations of pain relief were assessed using a numerical rating scale (-10 [most negative] to 10 [most positive]).

RESULTS

Change in quadriceps and trapezius PPT after the squat exercise showed a large difference between the positive and negative information groups (quadriceps, 102 kPa; 95% confidence interval, 55-150; effect size, 1.2; trapezius, 41 kPa; 95% confidence interval, 16-65; effect size:, 0.9). The positive information group had a 22% increase in quadriceps PPT whereas the negative information group had a 4% decrease. A positive correlation was found between expectations and increase in PPT.

CONCLUSIONS

Negative preexercise information caused hyperalgesia after the wall squat exercise, whereas positive or neutral preexercise information caused hypoalgesia. Positive preexercise information did not change the magnitude of EIH compared with neutral information.

Pressure pain thresholds in children before and after surgery: a prospective study

Background and aims This prospective study aimed to assess pressure pain thresholds (PPTs) by pressure algometry and the correlation to postoperative pain in children undergoing orthopaedic surgery. We hypothesized, that the PPTs would decline immediately after elective orthopaedic surgery and return to baseline values at follow-up. Methods Thirty children aged 6-16 years were included. PPTs and intensity of pain (Numerical Rating Scale, NRS) were assessed 3-6 weeks before surgery (baseline), 1-2 h before surgery (Day 0), the first postoperative day (Day 1) and 6-12 weeks after surgery (Follow-up). Results A significant difference of PPTs between the four assessments was seen using the Friedman test for detecting differences across multiple tests and Wilcoxon signed-rank test with a Bonferroni adjustment. The changes in PPTs between baseline (PPTcrus = 248 kPa, PPTthenar = 195 kPa) and day 1 (PPTcrus = 146 kPa, PPTthenar = 161 kPa) showed a decline of PPTs as hypothesized (Zcrus = 2.373, p = 0.018; Zthenar = 0.55, p = 0.581). More surprisingly, a significant decrease in PPTs between baseline and day 0, just before surgery (PPTcrus = 171 kPa, PPTthenar = 179 kPa), was also measured (Zcrus = 2.475, p = 0.013; Zthenar = 2.414, p = 0.016). PPTs were positively correlated to higher age, weight and height; but not to NRS or opioid equivalent use. Conclusions Children undergoing orthopaedic surgery demonstrate significant changes in PPTs over time. The PPTs decrease significantly between baseline and day 0, further decreases the first day postoperatively and returns to baseline values at follow-up. This suggests that other factors than surgery modulate the threshold for pain. Implications Awareness of pressure pain thresholds may help identify children with affected pain perception and hence improve future pain management in children undergoing orthopaedic surgery. Factors as for example anticipatory anxiety, psychological habitus, expected pain, catastrophizing, distraction, physical activity, patient education and preoperative pain medication might play a role in the perception of pain and need further investigation.

Effects of Low-Level Laser Therapy and Chiropractic Care on Back Pain in Quarter Horses

Low-level laser therapy has been used clinically to treat musculoskeletal pain; however, there is limited evidence available to support its use in treating back pain in horses. The objective of this study was to evaluate the clinical effectiveness of low-level laser therapy and chiropractic care in treating thoracolumbar pain in competitive western performance horses. The subjects included 61 Quarter Horses actively involved in national western performance competitions judged to have back pain. A randomized, clinical trial was conducted by assigning affected horses to either laser therapy, chiropractic, or combined laser and chiropractic treatment groups. Outcome parameters included a visual analog scale (VAS) of perceived back pain and dysfunction and detailed spinal examinations evaluating pain, muscle tone, and stiffness. Mechanical nociceptive thresholds were measured along the dorsal trunk and values were compared before and after treatment. Repeated measures with post-hoc analysis were used to assess treatment group differences. Low-level laser therapy, as applied in this study, produced significant reductions in back pain, epaxial muscle hypertonicity, and trunk stiffness. Combined laser therapy and chiropractic care produced similar reductions, with additional significant decreases in the severity of epaxial muscle hypertonicity and trunk stiffness. Chiropractic treatment by itself did not produce any significant changes in back pain, muscle hypertonicity, or trunk stiffness; however, there were improvements in trunk and pelvic flexion reflexes. The combination of laser therapy and chiropractic care seemed to provide additive effects in treating back pain and trunk stiffness that were not present with chiropractic treatment alone. The results of this study support the concept that a multimodal approach of laser therapy and chiropractic care is beneficial in treating back pain in horses involved in active competition.

A Subgroup of Chronic Low Back Pain Patients With Central Sensitization

BACKGROUND

Our knowledge of central sensitization (CS) in chronic low back pain (CLBP) is limited. 2011 fibromyalgia criteria and severity scales (2011 FM survey) have been used to determine FM positive as a surrogate of CS. The major features of CS including widespread hyperalgesia and dysfunction of the descending inhibitory pathways can be identified by pressure pain threshold (PPT) and conditioned pain modulation (CPM) tests. The purpose of the study was to examine neurophysiological characteristics and psychosocial symptoms in a subgroup of FM-positive CLBP compared with FM-negative CLBP patients.

METHODS

A total of 46 participants with CLBP and 22 pain-free controls completed outcome measures of the 2011 FM survey, PPT and CPM tests, and psychosocial questionnaires. Differences between FM-positive and FM-negative CLBP participants on these measures and correlations were analyzed.

RESULTS

The 2011 FM survey identified 22 (48%) participants with CLBP as FM positive. FM-positive CLBP participants showed lower PPT values of the thumbnail (P=0.011) and lower back (P=0.003), lower CPM values of the thumbnail (P=0.002), and more severe pain catastrophizing, anxiety, and depression symptoms (P<0.05) than FM-negative CLBP participants. The 2011 FM scores were significantly correlated with the PPT and CPM values of the thumbnail and with psychosocial symptoms (P<0.001).

DISCUSSION

Our findings suggest a subgroup of CLBP patients exhibiting with signs and symptoms of CS. Associations between subjective and objective CS measures indicate that the 2011 FM survey can be utilized to identify the presence of CS in CLBP in clinical practice.

Neuropsychological functions of verbal recall and psychomotor speed significantly affect pain tolerance

Background

Effects from cognitive performance on pain tolerance have been documented, however, sample sizes are small and confounders often overlooked. We aimed to establish that performance on neuropsychological tests was associated with pain tolerance, controlling for salient confounders.

Methods

This was a cross‐sectional study nested within the Tromsø‐6 survey. Neuropsychological test performance and the cold pressor test were investigated in 4,623 participants. Due to significant interaction with age, participants were divided into three age groups (<60, ≥60 to <70 and ≥70 years). Cox proportional hazard models assessed the relationship between neuropsychological tests and cold pressure pain tolerance, using hand‐withdrawal as event. The fully adjusted models controlled for sex, education, BMI, smoking status, exercise, systolic blood pressure, sleep problems and mental distress.

Results

In the adjusted models, participants aged ≥70 years showed a decreased hazard of hand withdrawal of 18% (HR 0.82, 95% CI (0.73, 0.92) per standard deviation on immediate verbal recall, and a decreased hazard of 23% (HR 0.77, 95% CI (0.65, 0.08) per standard deviation on psychomotor speed. Participants aged ≥60 to <70 years had a significant decreased hazard of 11% (HR 0.89, 95% CI (0.80, 0.98) per standard deviation on immediate word recall. In participants aged <60 years, there was a decreased hazard of 14% (HR 0.86 95% CI: 0.76, 0.98), per standard deviation on psychomotor speed.

Conclusion

Better performance on neuropsychological tests increased pain tolerance on the cold pressor test. These exposure effects were present in all age groups.

Significance

This paper describes substantial associations between cognitive functioning and cold pressor tolerance in 4,623 participants. Reduced psychomotor speed and poor verbal recall gave greater odds for hand‐withdrawal on the cold pressor task. The associations were stronger in older participants, indicating an interaction with age.

Exercise-induce hyperalgesia, complement system and elastase activation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome - a secondary analysis of experimental comparative studies

Background and aims The interaction between the immune system and pain has been thoroughly explored in the recent decades. The release of inflammatory mediators from immune cells has the capability of activating neurons and glial cells, in turn sensitizing the nervous system. Both immune system alterations and pain modulation dysfunctions have been shown in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) following exercise. However, no studies tried to explore whether these two phenomena are linked and can explain exercise-induced symptoms worsening in people with ME/CFS. We hypothesized that exercise-induced changes in descending pain modulation is associated to changes in immune system functions. We used complement system product C4a and elastase activity as indicators of immune system activity. Methods The study design was a secondary analysis of controlled experimental studies. Twenty-two patients with ME/CFS and 22 healthy sedentary controls were enrolled. In experiment 1, subjects performed an aerobic submaximal exercise test; in experiment 2 they underwent a self-paced exercise test. One week of rest period were set between the two exercise tests. Before and after each experiment, subjects underwent clinical assessment, pain thresholds (PPTs) measurement, and blood sampling. Immune system function was assessed measuring complement system C4a products and elastase activity. Results Changes in elastase activity were not associated to changes in PPTs. Associations were observed in the ME/CFS group between changes in PPTs and C4a products, following both types of exercise. After submaximal exercise, the change in C4a products was associated with the change in PPT at the thumb in patients (r=0.669, p=0.001). Similarly, after self-paced exercise the change in C4a products was associated witht the change in PPT at the calf in patients (r=0.429, p=0.047). No such correlations were found in healthy controls. Regression analysis showed that C4a changes after the submaximal exercise significantly predicted the change in PPTs (R2=0.236; p=0.02). Conclusions Moderate associations between exercise-induced changes in PPTs and immune system activity were found only in ME/CFS. The change in the complement system following submaximal exercise might be able to explain part of the change in patient's pain thresholds, providing evidence for a potential link between immune system alteration and dysfunctional endogenous pain modulation. These results have to be taken with caution, as only one out of three measures of PPTs was found associated with C4a changes. We cannot reject the hypothesis that C4a might therefore be a confounding factor, and changes during exercise might be mediated by other mechanism. Implications Immune system changes following exercise might contribute to exercise-induced symptoms worsening in patients with ME/CFS. However, the role of the complement system is questionable.

Lack of Exercise-Induced Hypoalgesia to Repetitive Back Movement in People with Chronic Low Back Pain

PURPOSE

To investigate whether people with chronic low back pain (LBP) show dysfunctional exercise-induced hypoalgesia (EIH) in response to repeated contractions of their back muscles during a lifting task.

METHODS

In this cross-sectional observational study conducted on asymptomatic participants (n = 18) and participants with chronic LBP (n = 21), quantitative sensory testing (QST) was applied extensively over the lumbar region and a remote area before and after a repeated task that involved lifting a 5-kg box for ~7 minutes. QST included pressure pain thresholds (PPTs), thermal detection, pain thresholds, and measures of temporal summation. Topographical maps of the percentage change in PPT detected at 16 locations over the lumbar region were generated to explore regional differences and compared between groups.

RESULTS

Mean (standard deviation) PPTs measured from 16 sites over the lower back changed significantly in asymptomatic participants (+29.78 kPa [41.4]) following task completion, indicative of EIH, whereas no significant change was observed for the low back pain (LBP) group (-14.87 kPa [61.2]). No changes were detected at the remote site for either group. No changes were revealed for the thermal tests. Temporal summation data revealed decreasing pain sensitivity as the test progressed, but the test response did not change after the exercise for either group.

CONCLUSION(S)

Unlike asymptomatic individuals, participants with LBP lacked EIH over the lumbar erector spinae muscles following repeated lifting. Although these results should be considered in relation to the study limitations, particularly the absence of a control group, the findings support impaired EIH in patients with LBP.

The relationship between catastrophizing and altered pain sensitivity in patients with chronic low-back pain

Changes in central pain processing have been shown in patients with chronic low-back pain (cLBP). We used quantitative sensory testing methods to identify differences in pain sensitization between patients with cLBP (N = 167) and healthy controls (N = 33). Results indicated that, compared with healthy pain-free controls, cLBP patients showed increased sensitivity and greater painful aftersensations for mechanical pressure and pin-prick stimuli and lower tactile spatial acuity in the 2-point discrimination task (ps < 0.05). Then, we examined the role of pain catastrophizing as a mediator of the group differences in pain sensitization. We found that catastrophizing partially accounted for group differences in pressure required to produce moderate pain. Finally, we examined the relationship between pain sensitization, catastrophizing, and clinical pain among patients with cLBP. We found that catastrophizing and deep-tissue pressure pain were associated with greater pain intensity in the past month, week, and at the visit as well as low-back pain bothersomeness. Furthermore, deep-tissue pressure pain mediated the associations between catastrophizing and both pain in the past month and low-back pain severity. Taken together, these results indicate that not only do patients with cLBP demonstrate increased pain sensitization and decreased sensitivity to innocuous stimuli, but these changes are also linked with increased catastrophizing. Furthermore, both catastrophizing and sensitization are associated with increased clinical pain among cLBP patients.

Effectiveness of the Pilates method versus aerobic exercises in the treatment of older adults with chronic low back pain: a randomized controlled trial protocol

BACKGROUND

Chronic low back pain is potentially disabling for older adults, and exercise is considered the best treatment. The Pilates method and aerobic exercises have been proven to be effective in pain and function improvement in patients with low back pain, but evidence in the treatment of older adults with low back pain is scarce. Therefore, the objective of this study is to investigate the effectiveness of the Pilates method compared to aerobic exercises in the treatment of older adults with chronic nonspecific low back pain.

METHODS

This is a randomized controlled trial with blinded assessor, to be held in a physical therapy clinic in Sao Paulo, Brazil. Seventy four patients aged 65 to 85 years with chronic nonspecific pain will be randomized into Pilates Group (n = 37) with exercises based on the Pilates method and Aerobic Group (n = 37) with treadmill aerobic exercise. The primary outcomes will be pain intensity and general disability, assessed eight weeks after randomization. The secondary outcomes will be: pain intensity and general disability, assessed six months after randomization; and global perceived improvement, specific disability, dynamic balance, muscle strength (gluteus maximus, gluteus medius, and lateral hip rotators), and pressure pain threshold, assessed eight weeks and six months after randomization. Therapists and patients will not be blinded.

DISCUSSION

This study has the potential to reduce pain and, consequently, improve balance and function of older adults with chronic low back pain with both therapies. However, Pilates may be more effective because the exercises are more targeted to the trunk stabilization muscles. The results of this study may provide valuable information on the effects of Pilates and aerobic exercise in older adults with chronic low back pain and contribute to a better selection of the treatment program according to the patient preference.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02729779 , April 6, 2016.

Exercise-induced hypoalgesia is present in people with Parkinson's disease: Two observational cross-sectional studies

BACKGROUND

Exercise is prescribed for people with Parkinson's disease to address motor and non-motor impairments, including pain. Exercise-induced hypoalgesia (i.e., an immediate reduction in pain sensitivity following exercise) is reported in the general population; however, the immediate response of pain sensitivity to exercise in people with Parkinson's disease is unknown. The purpose of this study was to investigate if exercise-induced hypoalgesia is present following isometric and aerobic exercise in people with Parkinson's disease, and if so, if it varies with the dose of aerobic exercise.

METHODS

Thirty people with idiopathic Parkinson's disease and pain-free age-matched controls completed two observational studies evaluating the response to: (a) right arm isometric exercise; and (b) treadmill walking at low and moderate intensities. Pressure pain thresholds were measured over biceps brachii and quadriceps muscles immediately before and after exercise, with increased thresholds after exercise indicating exercise-induced hypoalgesia.

RESULTS

Pressure pain thresholds increased in the Parkinson's disease group at all tested sites following all exercise bouts (e.g., isometric exercise, right bicep 29%; aerobic exercise, quadriceps, moderate intensity 8.9%, low intensity 7.1% (p ≤ 0.008)), with no effect of aerobic exercise dose (p = 0.159). Similar results were found in the control group.

CONCLUSIONS

Overall, people with Parkinson's disease experienced an exercise-induced hypoalgesia response similar to that of the control group, the extent of which did not vary between mild and moderate doses of aerobic exercise. Further research is warranted to investigate potential longer term benefits from exercise in the management of pain in this population.

SIGNIFICANCE

Isometric and aerobic exercise reduces pain sensitivity in people with Parkinson's disease. As exercise is important for people with Parkinson's disease, these results provide assurance that people with Parkinson's disease and pain can exercise without an immediate increase in pain sensitivity. The reduction in pain sensitivity with both modes and with low and moderate intensities of aerobic exercise suggests that people with Parkinson's disease can safely choose the mode and intensity of exercise that best suits their needs.

The association between back muscle characteristics and pressure pain sensitivity in low back pain patients

BACKGROUND AND AIMS

Some low back pain (LBP) patients recover after every pain episode whereas others develop chronicity. Research indicates that the amount of atrophy and fat infiltration differs between patients with LBP. Also enhanced pain sensitivity is present only in a subgroup of LBP patients. The relationship between pain sensitivity and muscular deformations in LBP, is however unexplored. This study examined the association between pressure pain sensitivity and the structural characteristics of the lumbar muscles in three different groups of non-specific LBP patients.

METHODS

This cross-sectional study examined the total cross-sectional area (CSA), fat CSA, muscle CSA and muscle fat index (MFI) of the lumbar multifidus (MF) and erector spinae (ES) at level L4 by magnetic resonance imaging in 54 patients with non-specific LBP (23 recurrent LBP, 15 non-continuous chronic LBP and 16 continuous chronic LBP). Pressure pain thresholds were measured at four locations (lower back, neck, hand and leg) by a manual pressure algometer and combined into one "pain sensitivity" variable. As a primary outcome measure, the association between pain sensitivity and muscle structure characteristics was investigated by multiple independent general linear regression models. Secondly, the influence of body mass index (BMI) and age on muscle characteristics was examined.

RESULTS

A positive association was found between pain sensitivity and the total CSA of the MF (p=0.006) and ES (p=0.001), and the muscle CSA of the MF (p=0.003) and ES (p=0.001), irrespective of the LBP group. No association was found between pain sensitivity and fat CSA or MFI (p>0.01). Furthermore, a positive association was found between BMI and the fat CSA of the MF (p=0.004) and ES (p=0.006), and the MFI of the MF (p<0.01) and ES (p=0.003). Finally, a positive association was found between age with the fat CSA of the MF (p=0.008) but not with the fat CSA of the ES (p>0.01), nor the MFI of the MF (p>0.01) and ES (p>0.01).

CONCLUSIONS

A higher pain sensitivity is associated with a smaller total and muscle CSA in the lumbar MF and ES, and vice versa, but results are independent from the LBP subgroup. On the other hand, the amount of fat infiltration in the lumbar muscles is not associated with pain sensitivity. Instead, a higher BMI is associated with more lumbar fat infiltration. Finally, older patients with LBP are associated with higher fat infiltration in the MF but not in the ES muscle.

IMPLICATIONS

These results imply that reconditioning muscular tissues might possibly decrease the pain sensitivity of LBP patients. Vice versa, therapy focusing on enhancement of pain sensitivity might also positively influence the CSA and that way contribute to the recovery of LBP. Furthermore, the amount of lumbar muscle fat seems not susceptible to pain sensitivity or vice versa, but instead a decrease in BMI might decrease the fat infiltration in the lumbar muscles and therefore improve the muscle structure quality in LBP. These hypothesis apply for all non-specific LBP patients, despite the type of LBP.

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.

Quantitative sensory testing in physically active individuals and patients who underwent multidisciplinary pain therapy in the longitudinal course

Objective

The aim of this study was to evaluate possible differences of quantitative sensory testing (QST) results in healthy individuals (group control, n=20), physically active individuals (group sport, n=30) and in patients suffering from chronic musculoskeletal pain (group pain, n=30).

Methods

Thermal detection thresholds, thermal pain thresholds and blunt pressure pain thresholds were measured at various sites (T0). Additionally, group pain was treated in multidisciplinary pain therapy for 4 weeks. All groups were retested after 4 weeks to evaluate the reliability of QST measurements and to investigate possible early changes following treatment (T1).

Results

Importantly, QST-measurements showed stable test results for group sport and group control at both time points. Athletes demonstrated the highest pain thresholds in general (cold pain threshold mean in degree Celsius for the hand: 5.76, lower back right: 7.25, lower back left: 7.53; heat pain threshold mean in degree Celsius for the hand: 46.08, lower back right: 45.77, lower back left: 45.70; and blunt pressure pain mean in kilograms for the hand: 3.54, lower back right: 5.26, lower back left: 5.46). Patients who underwent therapy demonstrated significant differences at T1 (cold pain threshold hand mean in degree Celsius for the hand: 11.12 [T0], 15.12 [T1]; and blunt pressure pain mean in kilograms for the lower back right: 2.87 [T0], 3.56 [T1]). They were capable of enduring higher blunt pressure, but on the other hand cold pain tolerance had decreased (P=0.045 and P=0.019, respectively).

Conclusions

In conclusion, we were able to demonstrate significant differences of QST results among the three groups and we detected early changes following multidisciplinary pain therapy, which will be discussed.

No immediate analgesic effect of diadynamic current in patients with nonspecific low back pain in comparison to TENS

BACKGROUND AND DESIGN

Chronic nonspecific low back pain (CNSLBP) has major socioeconomic as well as personal impact in many industrialized and developing countries. Physiotherapy is a common intervention for this group of patients and using anti-pain physical modalities is a common part of the physical therapy. In a randomized controlled trial we investigated the immediate effect of the Diadynamic current in comparison to TENS on reducing the pain in patients suffering from non specific chronic low back pain.

METHODS

Thirty patients were randomized into the Diadynamic current and TENS groups. Electrical stimulation was applied for 10 min in the Diadynamic group and for 15 min in the TENS group for one session. Pain, on a 100 mm Visual Analog Scale, and Pressure Pain Threshold (PPT), using an Algometer, was measured before the treatment, after the current application, 20 min later and after 48 h.

RESULTS

Pain was decreased significantly after 20 min following the current application only in the TENS group, with no improvement at all measurement points in the group receiving Diadynamic current. PPT was increased immediately after current application in both groups but did not last until later measurements.

CONCLUSION

Diadynamic current had no positive effect on prompt relief of pain in patients suffering from recurrent CNSLBP.

Cluster subgroups based on overall pressure pain sensitivity and psychosocial factors in chronic musculoskeletal pain: Differences in clinical outcomes

Objective: We aimed to empirically derive psychosocial and pain sensitivity subgroups using cluster analysis within a sample of individuals with chronic musculoskeletal pain (CMP) and to investigate derived subgroups for differences in pain and disability outcomes. Methods: Eighty female participants with CMP answered psychosocial and disability scales and were assessed for pressure pain sensitivity. A cluster analysis was used to derive subgroups, and analysis of variance (ANOVA) was used to investigate differences between subgroups. Results: Psychosocial factors (kinesiophobia, pain catastrophizing, anxiety, and depression) and overall pressure pain threshold (PPT) were entered into the cluster analysis. Three subgroups were empirically derived: cluster 1 (high pain sensitivity and high psychosocial distress; n = 12) characterized by low overall PPT and high psychosocial scores; cluster 2 (high pain sensitivity and intermediate psychosocial distress; n = 39) characterized by low overall PPT and intermediate psychosocial scores; and cluster 3 (low pain sensitivity and low psychosocial distress; n = 29) characterized by high overall PPT and low psychosocial scores compared to the other subgroups. Cluster 1 showed higher values for mean pain intensity (F_(2,77) = 10.58, p < 0.001) compared with cluster 3, and cluster 1 showed higher values for disability (F_(2,77) = 3.81, p = 0.03) compared with both clusters 2 and 3. Conclusions: Only cluster 1 was distinct from cluster 3 according to both pain and disability outcomes. Pain catastrophizing, depression, and anxiety were the psychosocial variables that best differentiated the subgroups. Overall, these results call attention to the importance of considering pain sensitivity and psychosocial variables to obtain a more comprehensive characterization of CMP patients' subtypes.

Exercise does not produce hypoalgesia when performed immediately after a painful stimulus

Background and aims:

Exercise-induced hypoalgesia (EIH) and conditioned pain modulation (CPM) are assumed to reflect descending pain inhibition. Potential interactions between EIH and CPM may be important in the therapy of chronic pain, as reduced CPM and increased pain after exercise are frequently observed. This study compared the EIH response after CPM was activated using a cold pressor task with the EIH response after a control condition.

Methods:

Thirty-one participants (age: 27.7±9.8; 15 female) completed two sessions: a cold pressor task (CPT) session, i.e. testing EIH with preceding CPM activation induced using a 2 min CPT at approximately 2°C, and a control session, i.e. testing EIH after a control condition (2 min of quiet rest). EIH was induced using a 15 min bicycling exercise at a target heart rate corresponding to 75% VO2 max. Repeated measures ANOVAs on pressure pain thresholds (PPTs) at the hand, back and leg were used to determine the effects of exercise after the cold pressor test and control condition. Furthermore, correlations between CPM and EIH, in the CPT session as well as control session, were calculated at each assessment site.

Results:

A significant time x condition interaction (F(1, 30)=43.61, p<0.001, partial η2=0.59), with Bonferroni-corrected post-hoc t-tests showed that PPTs increased after exercise in the control session (p<0.001), but not in the CPT session (p=0.125). Furthermore, there was a small positive correlation of EIH in the control session and CPM at the hand (r=0.37, p=0.043). There was a moderate negative correlation of EIH in the CPT session and CPM at the hand (r=−0.50, p=0.004), and smaller negative correlations at the back (r=−0.37, p=0.036) and at the leg (r=−0.35, p=0.054).

Conclusions:

Attenuated EIH after the CPM activation in comparison to a control condition suggests that EIH and CPM may share underlying pain inhibitory mechanisms on a systemic level. This assumption is further supported by the finding of small to moderate significant correlations between EIH and CPM at the hand. The attenuated EIH response furthermore suggests that these mechanisms are exhaustible, i.e. that its effects decline after a certain amount of inhibition.

Implications:

In patients with chronic pain, assessing the current capacity of the descending pain inhibitory system – as indicated by the CPM response – may aid to make better predictions about how patients will respond to exercise with respect to acute pain reduction.

Convergent Validity of the Dutch Central Sensitization Inventory: Associations with Psychophysical Pain Measures, Quality of Life, Disability, and Pain Cognitions in Patients with Chronic Spinal Pain

OBJECTIVE

Symptoms of central sensitization (CS) have been described in patients with chronic spinal pain (CSP). Although a gold standard to diagnose CS is lacking, psychophysical pain measures are often used. The Central Sensitization Inventory (CSI) is proposed as an alternative method and indirect tool for the evaluation of CS symptomatology. The aim of the current study was to evaluate the convergent validity of the CSI by investigating the association with psychophysical pain measures and self-reported measures of current pain intensity, quality of life, disability, and catastrophizing in CSP patients.

METHODS

One hundred sixteen patients with nonspecific CSP were included in the present study. Patients completed the CSI, were subjected to pressure pain thresholds (PPTs) and a conditioned pain modulation (CPM) paradigm, and completed questionnaires for current pain intensity, quality of life, pain disability, and pain catastrophizing.

RESULTS

Higher CSI scores were weakly correlated with lower PPTs (-0.276 ≤ r ≤ -0.237; all P ≤ 0.01) and not with CPM efficacy (r = 0.017; P = 0.858). Higher CSI scores were moderately correlated with higher current pain intensity (r = 0.320; P < 0.001), strongly correlated with lower physical (r = -0.617; P < 0.001) and emotional (r = -0.635; P < 0.001) quality of life, and moderately correlated with higher pain disability (r = 0.472; P < 0.001) and higher pain catastrophizing (r = 0.464; P < 0.001).

CONCLUSION

The CSI was weakly associated with PPTs and not with CPM efficacy in CSP patients. Moderate to strong associations were found with current pain intensity, quality of life, disability, and catastrophizing. The current results illustrate that the CSI does not reflect a direct measure of CS, yet is a representation of general distress, possible originating from CS symptoms.

Office-Cycling: A Promising Way to Raise Pain Thresholds and Increase Metabolism with Minimal Compromising of Work Performance

Aim

Establishing the effects of low intensity cycling (LC), moderate intensity cycling (MC), and standing at a simulated office workstation on pain modulation, work performance, and metabolic expenditure.

Methods

36 healthy adults (21 females), mean age 26.8 (SD 7.6) years, partook in this randomized 3 × 3 crossover trial with 75 minutes of LC on 20% of maximum aerobic power (MAP) output, 30 minutes of MC on 50% of MAP, and standing 30 minutes with 48-hour wash-out periods. Outcome measures were pain modulation (pressure pain threshold (PPT) and thermal pain threshold)), work performance (transcription, mouse pointing, and cognitive performance), and metabolic expenditure.

Results

PPTs increased in all conditions. PPT trapezius showed the highest increase after LC, 39.3 kilopascals (kPa) (15.6; 78.6), compared to MC, 17.0 kPa (2.8; 49.9), and standing, 16.8 kPa (-5.6; 39.4), p = 0.015. Transcription was reduced during LC and MC. Mouse pointing precision was best during standing and worst and slowest during MC. Cognitive performance did not differ between conditions. Metabolic expenditure rates were 1.4 (1.3; 1.7), 3.3 (2.3; 3.7), and 7.5 (5.8; 8.7) kcal/minute during standing, LC, and MC, respectively (p < 0.001).

Conclusions

LC seems to be the preferred option; it raised PPTs, more than doubled metabolic expenditure, whilst minimally influencing work performance.

Mechanisms Explaining Muscle Fatigue and Muscle Pain in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): a Review of Recent Findings

PURPOSE OF REVIEW

Here, we review potential causes of muscle dysfunction seen in many patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) such as the effects of oxidative and nitrosative stress (O&NS) and mitochondrial impairments together with reduced heat shock protein production and a range of metabolic abnormalities.

RECENT FINDINGS

Several studies published in the last few years have highlighted the existence of chronic O&NS, inflammation, impaired mitochondrial function and reduced heat shock protein production in many patients with ME/CFS. These studies have also highlighted the detrimental effects of chronically elevated O&NS on muscle functions such as reducing the time to muscle fatigue during exercise and impairing muscle contractility. Mechanisms have also been revealed by which chronic O&NS and or impaired heat shock production may impair muscle repair following exercise and indeed the adaptive responses in the striated muscle to acute and chronic increases in physical activity. The presence of chronic O&NS, low-grade inflammation and impaired heat shock protein production may well explain the objective findings of increased muscle fatigue, impaired contractility and multiple dimensions of exercise intolerance in many patients with ME/CFS.

The effects of Nordic Walking training on selected upper-body muscle groups in female-office workers: A randomized trial

BACKGROUND

Regular Nordic Walking training could improve fitness and reduce tenderness in selected muscle groups in office workers.

OBJECTIVE

An assessment of the effects of a 12-week Nordic Walking training program on the perceived pain threshold (PPT) and the flexibility of selected upper-body muscle groups in postmenopausal female office workers.

METHODS

39 office workers were selected at random for the treatment group (NWg, n = 20) and the control group (Cg, n = 19). The persons from the NW group completed a 12-week Nordic Walking training program (3 times a week/1 hour). PPTs measurements in selected muscles and functional tests evaluating upper-body flexibility (Back Scratch - BS) were carried out twice in every participant of the study: before and after the training program.

RESULTS

A significant increase in PPT (kg/cm2) was observed in the following muscles in the NW group only: upper trapezius (from 1,32 kg/cm2 to 1,99 kg/cm2), mid trapezius (from 2,92 kg/cm2 to 3,30 kg/cm2), latissimus dorsi (from 1,66 kg/cm2 to 2,21 kg/cm2) and infraspinatus (from 1,63 kg/cm2 to 2,93 kg/cm2). Moreover, a significant improvement in the BS test was noted in the NW group compared with the control group (from -1,16±5,7 cm to 2,18±5,1 cm in the NW group vs from -2,52±6,1 to -2,92±6,2 in the control group).

CONCLUSIONS

A 12-week Nordic Walking training routine improves shoulder mobility and reduces tenderness in the following muscles: trapezius pars descendens and middle trapezius, infraspinatus and latissimus dorsi, in female office workers.

General Exercise Does Not Improve Long-Term Pain and Disability in Individuals With Whiplash-Associated Disorders: A Systematic Review

Study Design Systematic review of randomized controlled trials. Background General exercise, defined as purposeful physical activity involving repetitive exercises and incorporating multiple muscle groups, is frequently used in the management of whiplash-associated disorders (WADs). Evidence supporting its efficacy is not well established. Objectives To determine whether general exercise is effective in reducing pain and disability in people with WAD. Methods Studies published in English in peer-reviewed journals between January 1990 and May 2015 were eligible if they evaluated a general exercise intervention compared with a different intervention or control. Studies were required to evaluate pain and disability at medium-term (6-14 weeks) and long-term (52 weeks) follow-ups. The mean ± SD and sample size were recorded for follow-up scores and for change scores from baseline to follow-up. Results Of the 3 high-quality studies that were eligible for inclusion, none investigated general exercise alone. There were no clinically meaningful differences between comprehensive exercise programs, which included general exercise, and minimal intervention controls in the medium and long term. No studies directly compared general exercise with a no-treatment control. All included studies used different control interventions, preventing meta-analysis. Conclusion A lack of significant long-term improvements from general exercise interventions in individuals with WAD was identified. This finding differs from the positive benefits of general exercise for other musculoskeletal conditions. This may, in part, relate to the complexity of whiplash conditions. This may also reflect the challenge of exercise prescription in this population, where the need for sufficient intensity is balanced against the impact that exercise has on pain. Level of Evidence Therapy, level 1a. J Orthop Sports Phys Ther 2017;47(7):472-480. Epub 16 Jun 2017. doi:10.2519/jospt.2017.7081.

Exercise induced hypoalgesia is elicited by isometric, but not aerobic exercise in individuals with chronic whiplash associated disorders

Background and aims

Reduced pain sensitivity following exercise is termed exercise induced hypoalgesia (EIH). Preliminary evidence suggests that impairment of EIH is evident in individuals with whiplash associated disorders (WAD) following submaximal aerobic exercise. This study aimed to compare EIH responses to isometric and aerobic exercise in patients with chronic WAD and healthy controls and investigate relationships between EIH, conditioned pain modulation (CPM) and psychological factors in patients with chronic WAD.

Methods

A cross sectional pre-post study investigated the effect of a single session of submaximal aerobic cycling exercise and a single session of isometric timed wall squat exercise on EIH in a group of participants with chronic WAD (n = 21) and a group of asymptomatic control participants (n = 19). Bivariate analyses between EIH and baseline measures of CPM and psychological features (fear of movement, pain catastrophization and posttraumatic stress symptoms) were also investigated.

Results

The isometric wall squat exercise but not the aerobic cycling exercise resulted in EIH in both groups (P < .023) with no between-group differences (P > .55) demonstrated for either exercise. There were no significant associations measured between EIH (for either exercise performed), and CPM, or any of the psychological variables.

Conclusions

This study showed that individuals with chronic WAD and mild to moderate pain and disability, and no evidence of dysfunctional CPM, demonstrated reduced pain sensitivity, both in the cervical spine and over the tibialis anterior following an isometric, timed wall squat exercise. Cycling exercise did not increase pain sensitivity.

Implications

Individuals with chronic WAD and mild to moderate levels of neck pain and disability may experience less pain sensitivity both locally and remotely following an exercise program directed at nonpainful muscles performing isometric exercises. Individuals cycling for 30 min at 75% of age-predicted heart rate maximum do not experience increased pain sensitivity.

Influence of exercise on visceral pain: an explorative study in healthy volunteers

Background and objectives

Contradictory results have been found about the effect of different exercise modalities on pain. The aim of this study was to investigate the early effects of aerobic and isometric exercise on different types of experimental pain, including visceral pain, compared to an active control condition.

Methods

Fifteen healthy subjects (6 women, mean [standard deviation] age 25 [6.5] years) completed 3 interventions consisting of 20 minutes of aerobic cycling, 12 minutes of isometric knee extension and a deep breathing procedure as active control. At baseline and after each intervention, psychophysical tests were performed, including electrical stimulation of the esophagus, pressure pain thresholds and the cold pressor test as a measure for conditioned pain modulation. Participants completed the Medical Outcome Study Short-Form 36 and State-Trait Anxiety Inventory prior to the experiments. Data were analyzed using two-way repeated measures analysis of variance.

Results

No significant differences were found for the psychophysical tests after the interventions, compared to baseline pain tests and the control condition.

Conclusion

No hypoalgesic effect of aerobic and isometric exercise was found. The evidence for exercise-induced hypoalgesia appears to be not as consistent as initially thought, and caution is recommended when interpreting the effects of exercise on pain.

Neuroimaging of Central Sensitivity Syndromes: Key Insights from the Scientific Literature

Central sensitivity syndromes are characterized by distressing symptoms, such as pain and fatigue, in the absence of clinically obvious pathology. The scientific underpinnings of these disorders are not currently known. Modern neuroimaging techniques promise new insights into mechanisms mediating these postulated syndromes. We review the results of neuroimaging applied to five central sensitivity syndromes: fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, temporomandibular joint disorder, and vulvodynia syndrome. Neuroimaging studies of basal metabolism, anatomic constitution, molecular constituents, evoked neural activity, and treatment effect are compared across all of these syndromes. Evoked sensory paradigms reveal sensory augmentation to both painful and nonpainful stimulation. This is a transformative observation for these syndromes, which were historically considered to be completely of hysterical or feigned in origin. However, whether sensory augmentation represents the cause of these syndromes, a predisposing factor, an endophenotype, or an epiphenomenon cannot be discerned from the current literature. Further, the result from cross-sectional neuroimaging studies of basal activity, anatomy, and molecular constituency are extremely heterogeneous within and between the syndromes. A defining neuroimaging "signature" cannot be discerned for any of the particular syndromes or for an over-arching central sensitization mechanism common to all of the syndromes. Several issues confound initial attempts to meaningfully measure treatment effects in these syndromes. At this time, the existence of "central sensitivity syndromes" is based more soundly on clinical and epidemiological evidence. A coherent picture of a "central sensitization" mechanism that bridges across all of these syndromes does not emerge from the existing scientific evidence.

Physiological and Psychological Predictors of Short-Term Disability in Workers with a History of Low Back Pain: A Longitudinal Study

Despite an elusive pathophysiology, common characteristics are often observed in individuals with chronic low back pain (LBP). These include psychological symptoms, altered pain perception, altered pain modulation and altered muscle activation. These factors have been explored as possible determinants of disability, either separately or in cross-sectional studies, but were never assessed in a single longitudinal study. Therefore, the objective was to determine the relative contribution of psychological and neurophysiological factors to future disability in individuals with past LBP. The study included two experimental sessions (baseline and six months later) to assess cutaneous heat pain and pain tolerance thresholds, pain inhibition, as well as trunk muscle activation. Both sessions included the completion of validated questionnaires to determine clinical pain, disability, pain catastrophizing, fear-avoidance beliefs and pain vigilance. One hundred workers with a history of LBP and 19 healthy individuals took part in the first experimental session. The second experimental session was exclusively conducted on workers with a history of LBP (77/100). Correlation analyses between initial measures and disability at six months were conducted, and measures significantly associated with disability were used in multiple regression analyses. A first regression analysis showed that psychological symptoms contributed unique variance to future disability (R² = 0.093, p = .009). To control for the fluctuating nature of LBP, a hierarchical regression was conducted while controlling for clinical pain at six months (R² = 0.213, p < .001) where pain inhibition contributed unique variance in the second step of the regression (R² change = 0.094, p = .005). These results indicate that pain inhibition processes may constitute potential targets for treatment to alleviate future disability in individuals with past or present LBP. Then again, the link between psychological symptoms and pain inhibition needs to be clarified as both of these factors are linked together and influence disability in their own way.

Mortality in Patients with Myalgic Encephalomyelitis and Chronic Fatigue Syndrome

BACKGROUND

There is a dearth of research examining mortality in individuals with myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Some studies suggest there is an elevated risk of suicide and earlier mortality compared to national norms. However, findings are inconsistent as other researchers have not found significant increases in all-cause mortality for patients.

OBJECTIVE

This study sought to determine if patients with ME or CFS are reportedly dying earlier than the overall population from the same cause.

METHODS

Family, friends, and caregivers of deceased individuals with ME or CFS were recruited through social media, patient newsletters, emails, and advocate websites. This study analyzed data including cause and age of death for 56 individuals identified as having ME or CFS.

RESULTS

The findings suggest patients in this sample are at a significantly increased risk of earlier all-cause (M = 55.9 years) and cardiovascular-related (M = 58.8 years) mortality, and they had a directionally lower mean age of death for suicide (M = 41.3 years) and cancer (M =66.3 years) compared to the overall U.S. population [M = 73.5 (all-cause), 77.7 (cardiovascular), 47.4 (suicide), and 71.1 (cancer) years of age].

CONCLUSIONS

The results suggest there is an increase in risk for earlier mortality in patients with ME and CFS. Due to the small sample size and over-representation of severely ill patients, the findings should be replicated to determine if the directional differences for suicide and cancer mortality are significantly different from the overall U.S. population.

Pressure and cold pain threshold reference values in a large, young adult, pain-free population

Background and aims

Currently there is a lack of large population studies that have investigated pain sensitivity distributions in healthy pain free people. The aims of this study were: (1) to provide sex-specific reference values of pressure and cold pain thresholds in young pain-free adults; (2) to examine the association of potential correlates of pain sensitivity with pain threshold values.

Methods

This study investigated sex specific pressure and cold pain threshold estimates for young pain free adults aged 21–24 years. A cross-sectional design was utilised using participants (n =617) from the Western Australian Pregnancy Cohort (Raine) Study at the 22-year follow-up. The association of site, sex, height, weight, smoking, health related quality oflife, psychological measures and activity with pain threshold values was examined. Pressure pain threshold (lumbar spine, tibialis anterior, neck and dorsal wrist) and cold pain threshold (dorsal wrist) were assessed using standardised quantitative sensory testing protocols.

Results

Reference values for pressure pain threshold (four body sites) stratified by sex and site, and cold pain threshold (dorsal wrist) stratified by sex are provided. Statistically significant, independent correlates of increased pressure pain sensitivity measures were site (neck, dorsal wrist), sex (female), higher waist-hip ratio and poorer mental health. Statistically significant, independent correlates of increased cold pain sensitivity measures were, sex (female), poorer mental health and smoking.

Conclusions

These data provide the most comprehensive and robust sex specific reference values for pressure pain threshold specific to four body sites and cold pain threshold at the dorsal wrist for young adults aged 21–24 years. Establishing normative values in this young age group is important given that the transition from adolescence to adulthood is a critical temporal period during which trajectories for persistent pain can be established.

Implications

These data will provide an important research resource to enable more accurate profiling and interpretation of pain sensitivity in clinical pain disorders in young adults. The robust and comprehensive data can assist interpretation of future clinical pain studies and provide further insight into the complex associations of pain sensitivity that can be used in future research.

Use of the PREPARE (PREhabilitation, Physical Activity and exeRcisE) program to improve outcomes after lumbar fusion surgery for severe low back pain: a study protocol of a person-centred randomised controlled trial

Background

Following lumbar fusion surgery, a successful outcome is empirically linked to effective rehabilitation. While rehabilitation is typically postoperative, the phase before surgery – termed prehabilitation – is reportedly an ideal time to prepare the patient. There are presently no guidelines for prehabilitation before lumbar fusion surgery. Physical activity has well-known health benefits, and staying physically active despite pain is a major principle in non-pharmacological chronic low back pain treatment. Psychological factors such as fear of movement, pain catastrophizing and low self-efficacy are known to be barriers to staying active. No studies have investigated prehabilitation protocols that promote physical activity and target psychological risk factors before lumbar fusion surgery. The aim of our proposed randomised controlled trial is to investigate whether patients who undergo lumbar fusion surgery for degenerative disc disease experience better functioning with a physiotherapeutic prehabilitation program (PREPARE) based on a cognitive behavioural approach compared to conventional care.

Methods/Design

We will recruit 110 patients between 18–70 years of age with degenerative disc disease who are waiting for lumbar fusion surgery. These patients will be randomly assigned to receive either PREPARE or conventional care. PREPARE uses a person-centred perspective and focuses on promoting physical activity and targeting psychological risk factors before surgery. The primary outcome will be disability measured using the Oswestry Disability Index 2.0. Secondary outcomes will include functioning (patient-reported and performance-based), physical activity (accelerometer), health-related quality of life, back and leg pain intensity, pain catastrophizing, kinesiophobia, self-efficacy, depression, anxiety, satisfaction with treatment results and health economic factors. Data will be collected at baseline (preoperatively) after the intervention (preoperatively), 3 and 8 weeks, 3, 6, 12, 24 and 60 months postoperatively.

Discussion

We hypothesise that the focus on promoting physical activity and targeting psychological risk factors before surgery will decrease disability and help the patients to be more active despite pain both before and after surgery. We will use a combination of outcome measures both patient-reported and performance-based, as well as accelerometer data. This will provide a more comprehensive picture of the patient’s functioning than just patient-reported outcomes alone.

Trial registration

Current Controlled Trials ISCRTN17115599, Retrospectively Registered 18 May 2015.

Pain following cancer treatment: Guidelines for the clinical classification of predominant neuropathic, nociceptive and central sensitization pain

BACKGROUND

In addition to fatigue, pain is the most frequent persistent symptom in cancer survivors. Clear guidelines for both the diagnosis and treatment of pain in cancer survivors are lacking. Classification of pain is important as it may facilitate more specific targeting of treatment. In this paper we present an overview of nociceptive, neuropathic and central sensitization pain following cancer treatment, as well as the rationale, criteria and process for stratifying pain classification.

MATERIAL AND METHODS

Recently, a clinical method for classifying any pain as either predominant central sensitization pain, neuropathic or nociceptive pain was developed, based on a large body of research evidence and international expert opinion. We, a team of 15 authors from 13 different centers, four countries and two continents have applied this classification algorithm to the cancer survivor population.

RESULTS

The classification of pain following cancer treatment entails two steps: (1) examining the presence of neuropathic pain; and (2) using an algorithm for differentiating predominant nociceptive and central sensitization pain. Step 1 builds on the established criteria for neuropathic pain diagnosis, while Step 2 applies a recently developed clinical method for classifying any pain as either predominant central sensitization pain, neuropathic or nociceptive pain to the cancer survivor population.

CONCLUSION

The classification criteria allow identifying central sensitization pain following cancer treatment. The recognition of central sensitization pain in practice is an important development in the integration of pain neuroscience into the clinic, and one that is relevant for people undergoing and following cancer treatment.

Understanding Muscle Dysfunction in Chronic Fatigue Syndrome

Introduction. Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a debilitating disorder of unknown aetiology, characterised by severe disabling fatigue in the absence of alternative diagnosis. Historically, there has been a tendency to draw psychological explanations for the origin of fatigue; however, this model is at odds with findings that fatigue and accompanying symptoms may be explained by central and peripheral pathophysiological mechanisms, including effects of the immune, oxidative, mitochondrial, and neuronal pathways. For example, patient descriptions of their fatigue regularly cite difficulty in maintaining muscle activity due to perceived lack of energy. This narrative review examined the literature for evidence of biochemical dysfunction in CFS/ME at the skeletal muscle level. Methods. Literature was examined following searches of PUB MED, MEDLINE, and Google Scholar, using key words such as CFS/ME, immune, autoimmune, mitochondria, muscle, and acidosis. Results. Studies show evidence for skeletal muscle biochemical abnormality in CFS/ME patients, particularly in relation to bioenergetic dysfunction. Discussion. Bioenergetic muscle dysfunction is evident in CFS/ME, with a tendency towards an overutilisation of the lactate dehydrogenase pathway following low-level exercise, in addition to slowed acid clearance after exercise. Potentially, these abnormalities may lead to the perception of severe fatigue in CFS/ME.