Examination of contraction-induced muscle pain as a behavioral correlate of physical activity in women with and without fibromyalgia

Exercise-induced hypoalgesia in chronic neck pain: A narrative review

Chronic neck pain (CNP) is a worldwide health problem with several risk factors. One of the most widely used treatments for managing this condition is therapeutic exercise, which could generate a response called exercise-induced hypoalgesia (EIH). There is no consensus on the best exercise modality to induce hypoalgesia. Therefore, this review aims to analyze and synthesize the state-of-the-art about the hypoalgesic effect of exercise in subjects with CNP. We included articles on EIH and CNP in patients older than 18 years, with pain for more than three months, where the EIH response was measured. Articles that studied CNP associated with comorbidities or measured the response to treatments other than exercise were excluded. The studies reviewed reported variable results. Exercise in healthy subjects has been shown to reduce indicators of pain sensitivity; however, in people with chronic pain, the response is variable. Some investigations reported adverse effects with increased pain intensity and decreased pain sensitivity, others found no clinical response, and some even reported EIH with decreased pain and increased sensitivity. EIH is an identifiable, stimulable, and helpful therapeutic response in people with pain. More research is still needed on subjects with CNP to clarify the protocols and therapeutic variables that facilitate the EIH phenomenon. In addition, it is necessary to deepen the knowledge of the intrinsic and extrinsic factors that influence EIH in people with CNP.

Mediating role of physical activity in the relationship between exercise-induced muscle pain and symptom severity in women with fibromyalgia

BACKGROUND

Individuals with fibromyalgia (FM) exhibit generalized hyperalgesia to pain stimuli, and physical activity (PA) is critical to manage FM symptoms.

PURPOSE

This study examined the relationship between exercise-induced muscle pain, symptom severity, and PA in 28 women with FM.

METHODS

Muscle pain rating (MPR) was assessed during 3 minutes of submaximal isometric handgrip exercise, whereas PA and symptom severity were evaluated via self-report questionnaires. The analysis examined the relationship between the variables, with the specific interest in the mediating role of PA in the relationship between exercise-induced muscle pain and symptom severity.

RESULTS

MPR was positively associated with symptom severity (b = 1.89; 95% CI = 0.01, 3.76; P = .048) and inversely associated with PA levels (b = -0.16; 95% CI = -0.30, -0.03; P = .021). PA levels were inversely associated with symptom severity (b = -7.94; 95% CI = -12.46, -3.42; P = .001). After statistically controlling for PA levels, the relationship between MPR and symptom severity was no longer significant (b = 0.60; Wald 95% CI = -1.05, 2.25; P = .474).

CONCLUSION

Results show the link between the variables, and specifically demonstrate that PA mediates the relationship between exercise-induced muscle pain and symptom severity.

Physical activity correlates in people with fibromyalgia: a systematic review

PURPOSE

Understanding the enablers of and barriers to physical activity (PA) participation in people with fibromyalgia (PwF) is an essential first step to developing effective PA interventions. This systematic review examined correlates of PA across the socio-ecological model (i.e., intra-personal, inter-personal, environmental, and policy level) in PwF.

MATERIALS AND METHODS

PubMed, Embase, and CINAHL were searched from inception until 12 July 2022. Keywords included "physical activity" or "exercise" and "fibromyalgia" or "fibrositis." Summary coding was used to quantify the PA correlates.

RESULTS

Out of 74 PA correlates retrieved from 39 articles (n = 9426), co-morbid depression and higher pain intensity were found to be consistent (i.e., reported in four or more articles) barriers to PA in PwF, while higher self-efficacy and better endurance were found to be consistent enablers to PA. Despite the abundance of evidence for the PA benefits for PwF, we only found consistent evidence for PA correlates at the intrapersonal level.

CONCLUSIONS

Health professionals should consider mental and physical health barriers when promoting PA in PwF. There remains a need to better understand social, environmental, and policy-related factors associated with PA participation in PwFImplications for rehabilitationCo-morbid depression is a notable barrier to physical activity participation in people with fibromyalgia.Experienced pain intensity should be considered as a barrier when promoting physical activity for people with fibromyalgia.Rehabilitation professionals should facilitate self-efficacy in physical activity interventions for people with fibromyalgia.Rehabilitation professionals should promote endurance when motivating people with fibromyalgia towards an active lifestyle.

Proof of concept of prehabilitation: a combination of education and behavioural change, to promote physical activity in people with fibromyalgia

OBJECTIVES

To establish proof of concept of a prehabilitation intervention, a combination of education and behavioural change, preceding a physical activity programme in people with fibromyalgia (FM).

SETTINGS

Open-label, feasibility clinical trial.

PARTICIPANTS

Eleven people with FM (10 women).

INTERVENTIONS

The prehabilitation intervention consisted of 4 weeks, 1 weekly session (~1 to 1.5 hours), aimed to increase self-efficacy and understand why and how to engage in a gentle and self-paced physical activity programme (6 weeks of walking with telephone support).

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was the acceptability and credibility of the intervention by means of the Credibility/Expectancy Questionnaire. Secondary outcomes comprised scales to measure FM severity, specific symptoms and sedentary behaviour. An exit interview was conducted to identify the strengths and weaknesses and barriers to the intervention.

RESULTS

One participant dropped out due to finding the walking programme excessively stressful. Participants expected the intervention would improve their symptoms by 22%-38% but resulted in 5%-26% improvements. Participants would be confident in recommending this intervention to a friend who experiences similar problems. The interviews suggested that the fluctuation of symptoms should be considered as an outcome and that the prehabilitation intervention should accomodate these fluctuation. Additional suggestions were to incorporate initial interviews (patient-centred approach), to tailor the programmes to individuals' priorities and to offer a variety of physical activity programmes to improve motivation.

CONCLUSIONS

This feasibility study demonstrated that our novel approach is acceptable to people with FM. Future interventions should pay attention to flexibility, symptoms fluctuation and patients support.

TRIAL REGISTRATION NUMBER

NCT03764397.

Effects of a single exercise session on pain intensity in adults with chronic pain: a systematic review and meta-analysis

BACKGROUND

Chronic pain is prevalent amongst society, making it necessary to find strategies to manage chronic pain. Regular exercise is efficacious; however, pain is a barrier to initiating exercise. A single exercise session is also believed to acutely reduce pain, however, the evidence for this is less robust.

OBJECTIVES

This systematic review and meta-analysis aimed to identify the effect of a single exercise session on pain intensity in adults with chronic pain.

METHODS

We searched eight databases and trial registries to identify randomised controlled trials evaluating the effect of a single exercise session on pain intensity in adults with chronic pain compared to a non-exercise control. Literature screening, data extraction, risk of bias (Cochrane 2.0) and quality assessment (GRADE) were conducted independently and in duplicate. Random-effects meta-analyses were performed using the metafor package in R.

RESULTS

We included 17 trials (46 study arms with 664 adults [44% female]). There were no significant differences in pain intensity (mean difference on a 0-10 scale) immediately post-exercise -0.02 (95% CI = -0.06, 0.62; I² = 77.1%) or up to 45-min post-exercise -0.17 (95% CI = -0.49, 0.16; I² = 34.2%). All trials were at high risk of bias and the overall confidence in these findings was very low.

CONCLUSION

A single exercise session did not reduce pain intensity up to 1-h post-exercise. Notably, increases in pain were not observed either, suggesting that while pain can be a barrier to initiating exercise, clinicians can educate patients on the unlikelihood of exercise acutely increasing pain intensity.

Fibromyalgia and Chronic Fatigue Syndromes: A systematic review and meta-analysis of cardiorespiratory fitness and neuromuscular function compared with healthy individuals

OBJECTIVE

To determine cardiorespiratory fitness and neuromuscular function of people with CFS and FMS compared to healthy individuals.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Medline, CINAHL, AMED, Cochrane Central Register of Controlled Trials (CENTRAL), and PEDro from inception to June 2022.

ELIGIBLE CRITERIA FOR SELECTING STUDIES

Studies were included if presenting baseline data on cardiorespiratory fitness and/or neuromuscular function from observational or interventional studies of patients diagnosed with FMS or CFS. Participants were aged 18 years or older, with results also provided for healthy controls. Risk of bias assessment was conducted using the Quality Assessment Tool for Quantitative Studies (EPHPP).

RESULTS

99 studies including 9853 participants (5808 patients; 4405 healthy controls) met our eligibility criteria. Random effects meta-analysis showed lower cardiorespiratory fitness (VO2max, anaerobic threshold, peak lactate) and neuromuscular function (MVC, fatigability, voluntary activation, muscle volume, muscle mass, rate of perceived exertion) in CFS and FMS compared to controls: all with moderate to high effect sizes.

DISCUSSION

Our results demonstrate lower cardiorespiratory fitness and muscle function in those living with FMS or CFS when compared to controls. There were indications of dysregulated neuro-muscular interactions including heightened perceptions of effort, reduced ability to activate the available musculature during exercise and reduced tolerance of exercise.

TRAIL REGISTRATION

PROSPERO registration number: (CRD42020184108).

Impaired Cardiac Autonomic Control in Women With Fibromyalgia Is Independent of Their Physical Fitness

BACKGROUND/OBJECTIVE

Evidence has suggested abnormal cardiac autonomic responses to exercise in patients with fibromyalgia (FM). However, it is not clear whether the dysautonomia represents a reduced physical fitness rather directly related to FM pathogenesis. Thus, we aimed to verify the cardiac autonomic responses before, during, and after a maximal incremental exercise in women with FM and whether these hypothesized alterations would be dependent with their physical fitness.

METHODS

This is a cross-sectional study with 23 FM women and 17 healthy women. The participants performed a maximal incremental cycling test to determine their maximal workload (Wmax) and were further matched by their Wmax (14 FM patients, Wmax: 128.6 ± 16.2 W; and 14 healthy women, Wmax: 131.9 ± 15.9 W). Beat-to-beat heart rate (HR) was continuously monitored to calculate HR variability indexes at rest, chronotropic reserve during exercise, and HR recovery.

RESULTS

Heart rate variability indexes related to vagal modulation were significantly lower in FM patients than in healthy women (p < 0.05). The chronotropic reserve and the HR recovery at 30, 120, 180, 300, and 600 seconds after exercise were all lower in FM patients compared with those of healthy women (p < 0.05). Similar findings were found when analysis was performed using the matched physical fitness subgroup.

CONCLUSIONS

The documented cardiac autonomic abnormalities at rest, during, and after exercise in FM patients persist even when physical fitness status is taken in account. Thus, strategies to attenuate the dysautonomia in FM patients must be considered.

Acute Caffeine Intake Reduces Perceived Exertion But Not Muscle Pain during Moderate Intensity Cycling Exercise in Women with Fibromyalgia

OBJECTIVE

Exacerbated perceived exertion and muscle pain responses during exercise might limit physical activity practice in fibromyalgia patients. Thus, nutritional strategies that can reduce perceived exertion and muscle pain during exercise in fibromyalgia patients would be useful. The purpose of this study was to investigate the effects of acute caffeine intake on the perceptions of exertion and muscle pain during a moderate intensity exercise in women with fibromyalgia.Method: Using a randomized, double-blinded, placebo-controlled and crossover experimental design, eleven sedentary women diagnosed with fibromyalgia (age: 44.6 ± 10.5 years; body mass index: 28.5 ± 4.5 kg.m^-2) ingested a capsule containing either caffeine (5 mg per kg of body mass) or cellulose (placebo), 60 minutes before performing a 30-minute constant-load cycling exercise, with work rate fixed at 50% of their individual peak workload attained in an incremental exercise test. Ratings of perceived leg muscle pain and perceived exertion were assessed every 5 minutes of exercise.Results: The perceived leg muscle pain was similar (F_(1,10) = 1.18, p = 0.30, ŋ² = 0.11) between caffeine (2.1 ± 1.2 arbitrary units) and placebo conditions (2.2 ± 0.9 arbitrary units). The perceived exertion, however, was on average 8 ± 6% lower (F_(1,10) = 12.13; p = 0.006; ŋ² = 0.55) during exercise in the caffeine condition (12.4 ± 1.3 arbitrary units) than in the placebo condition (13.1 ± 1.1 arbitrary units).Conclusions: These findings indicate that acute caffeine intake could be an attractive strategy to attenuate the exacerbated perceived exertion of fibromyalgia patients during moderate intensity exercise.

Acute effect of strength training on pain in women with fibromyalgia: A brief report

OBJECTIVE

The aim was to analyze the effect of one session and three sessions of strength training (ST) on pain in women with fibromyalgia (FM).

METHOD

Twenty-three women with FM performed three sessions of ST for a week. Each training session worked the main muscle groups and lasted 60 min. Three sets of 12 repetitions were performed with 1 min intervals in between. The load was increased based on the perception of subjective effort of each patient. Pain intensity was evaluated immediately after the first and third sessions using a Fischer digital algometer.

RESULTS

After the first ST session, pain reduction was observed. No significant differences were found in pain thresholds on the baseline versus the third session. The analysis of MBI demonstrated that the ST does not worsen patients' pain, indicating a 52.2% trivial effect and a 39.1% beneficial effect.

CONCLUSION

Our results suggest that there is no harmful effect on the pain of women with FM after an acute session of ST. We emphasize that despite the promising results, more studies on the subject are needed to help understand pain in patients with FM.

Impaired exercise-induced hypoalgesia in individuals reporting an increase in low back pain during acute exercise

OBJECTIVES

Exercise therapy is recommended for low back pain (LBP) although the immediate effects on pain are highly variable. In 96 individuals with LBP this cross-sectional study explored (a) the magnitude of exercise-induced hypoalgesia (EIH) and (b) measures of pain sensitivity and clinical pain manifestations in individuals reporting a clinical relevant increase in back pain during physical activity compared with individuals reporting low or no increase in back pain during physical activity.

METHODS

Cuff algometry was performed at baseline on the leg to assess pressure pain threshold (cPPT), tolerance (cPTT) and temporal summation of pain (cTSP). Manual PPTs were assessed on the back and leg before and after a 6-min walk test (6MWT). Back pain was scored on a numerical rating scale (NRS) after each minute of walking. The EIH-effect was estimated as the increase in PPTs after the walk exercise.

RESULTS

Twenty-seven individuals reported an increase of ≥2/10 in pain NRS scores during walking and compared with the individuals with <2/10 NRS scores: cPPT and EIH-effects were lower whereas cTSP, pain intensity and disability were increased (p < 0.03). Baseline NRS scores, EIH and pain thresholds were associated with the likelihood of an increase of ≥2/10 in back pain intensity during walking (p < 0.05).

CONCLUSIONS

Pain flares in response to physical activity in individuals with LBP seem to be linked with baseline pain sensitivity and pain intensity, and impair the beneficial EIH. Such information may better inform when individuals with LBP will have a beneficial effect of physical activity.

SIGNIFICANCE

Pain flares in response to physical activity in individuals with LBP seem to be linked with baseline pain sensitivity and pain intensity, and impair the beneficial exercise-induced hypoalgesia. Such information may better inform when individuals with LBP will have a beneficial effect of physical activity.

Exercise-induced hypoalgesia after acute and regular exercise: experimental and clinical manifestations and possible mechanisms in individuals with and without pain

This review describes methodology used in the assessment of the manifestations of exercise-induced hypoalgesia in humans and previous findings in individuals with and without pain. Possible mechanisms and future directions are discussed.

Exercise and physical activity is recommended treatment for a wide range of chronic pain conditions. In addition to several well-documented effects on physical and mental health, 8 to 12 weeks of exercise therapy can induce clinically relevant reductions in pain. However, exercise can also induce hypoalgesia after as little as 1 session, which is commonly referred to as exercise-induced hypoalgesia (EIH). In this review, we give a brief introduction to the methodology used in the assessment of EIH in humans followed by an overview of the findings from previous experimental studies investigating the pain response after acute and regular exercise in pain-free individuals and in individuals with different chronic pain conditions. Finally, we discuss potential mechanisms underlying the change in pain after exercise in pain-free individuals and in individuals with different chronic pain conditions, and how this may have implications for clinical exercise prescription as well as for future studies on EIH.

Correlation Between Habitual Physical Activity and Central Sensitization, Pain Intensity, Kinesiophobia, Catastrophizing, and the Severity of Myogenous Temporomandibular Disorder

Objective

We sought to correlate habitual physical activity with central sensitization, pain intensity, kinesiophobia, catastrophizing, and the severity of chronic myogenous temporomandibular disorder (TMD).

Methods

This was an observational study. Fifty-five individuals, male and female, aged 18 to 45 years, with pain for at least 3 months (chronic) related to myogenous TMD were included in the study. Myogenous TMD was evaluated by means of the Numerical Rating Scale, Catastrophic Thoughts on Pain Scale, Tampa Scale for Kinesiophobia, Fonseca Anamnestic Index, Central Sensitization Inventory, and habitual physical activity by means of the Baecke Questionnaire (BQ). The Spearman correlation coefficient (r _s) was applied to verify the association of the BQ score with the pain variables.

Results

No significant correlations (P > .05) were observed in the total or mean BQ scores (both r _s = -0.17 to -0.04), nor in the analyses performed on the occupational (r _s = -0.03 to 0.14), sport (r _s = -0.16 to 0.01), and leisure domains (r _s = -0.16 to -0.02).

Conclusion

Habitual physical activity as measured by the BQ is not associated with pain intensity, catastrophizing, kinesiophobia, central sensitization, or the severity of chronic myogenous TMD.

The dosing of aerobic exercise therapy on experimentally-induced pain in healthy female participants

Knowledge of efficacious dosing respective to exercise type and pain condition is extremely limited in the literature. This study aimed to determine the impact of dose of moderate intensity treadmill walking on experimentally-induced pain in healthy human participants. Forty females were divided into 4 groups: control (no exercise), low dose exercise (3×/wk), moderate dose exercise (5×/wk) or high dose exercise (10×/wk). Over a 7-day period, subjects performed treadmill walking during assigned exercise days. Both qualitative and quantitative measures of pain were measured at baseline, during the trial, and 24 hrs post-final intervention session via sensitivity thresholds to painful thermal and painful pressure stimulation. Significant effects of treatment were found post-intervention for constant pressure pain intensity (p = 0.0016) and pain unpleasantness ratings (p = 0.0014). Post-hoc tests revealed significant differences between control and moderate and control and high dose groups for constant pressure pain intensity (p = 0.0015), (p = 0.0094), respectively and constant pressure pain unpleasantness (p = 0.0040), (p = 0.0040), respectively. Moderate and high dose groups had the greatest reductions in ratings of pain, suggesting that our lowest dose of exercise was not sufficient to reduce pain and that the moderate dose of exercise may be a sufficient starting dose for exercise-based adjuvant pain therapy.

P2X3 receptors contribute to muscle pain induced by static contraction by a mechanism dependent on neutrophil migration

P2X3 receptors are involved with several pain conditions. Muscle pain induced by static contraction has an important socioeconomic impact. Here, we evaluated the involvement of P2X3 receptors on mechanical muscle hyperalgesia and neutrophil migration induced by static contraction in rats. Also, we evaluated whether static contraction would be able to increase muscle levels of TNF-α and IL-1β. Male Wistar rats were pretreated with the selective P2X3 receptor antagonist, A-317491, by intramuscular or intrathecal injection and the static contraction-induced mechanical muscle hyperalgesia was evaluated using the Randall-Selitto test. Neutrophil migration was evaluated by measurement of myeloperoxidase (MPO) kinetic-colorimetric assay and the cytokines TNF-α and IL-1β by enzyme-linked immunosorbent assay. Intramuscular or intrathecal pretreatment with A-317491 prevented static contraction-induced mechanical muscle hyperalgesia. In addition, A-317491 reduced static contraction-induced mechanical muscle hyperalgesia when administered 30 and 60 min of the beginning of static contraction, but not after 30 and 60 min of the end of static contraction. Intramuscular A-317491 also prevented static contraction-induced neutrophil migration. In a period of 24 h, static contraction did not increase muscle levels of TNF-α and IL-1β. These findings demonstrated that mechanical muscle hyperalgesia and neutrophil migration induced by static contraction are modulated by P2X3 receptors expressed on the gastrocnemius muscle and spinal cord dorsal horn. Also, we suggest that P2X3 receptors are important to the development but not to maintenance of muscle hyperalgesia. Therefore, P2X3 receptors can be pointed out as a target to musculoskeletal pain conditions induced by daily or work-related activities.

Postural counseling represents a novel option in pain management of fibromyalgia patients

Background

Chronic pain is a key symptom in fibromyalgia (FM), and its management is still challenging for rheumatologists in daily practice. FM patients show psychological and psychiatric manifestations, going from mood and emotional disorders to depression and alexithymia that negatively impact their quality of life, limiting their daily activities. Since pharmacological strategies have a limited efficacy in FM pain, alternative or complementary non-pharmacological approaches have been introduced in the clinical management of FM.

Patients and methods

This is a retrospective study on FM patients (n=52) treated with a novel integrated postural counseling (PC) rehabilitation program carried out by a counselor physiotherapist. The clinical impact of PC was evaluated by 1) a semi-structured interview using an ad hoc modified questionnaire McGill Illness Narrative Interview (MINI) 1 to obtain data on pain management by highlighting everyday experience of living with pain and 2) an FM impact questionnaire (FIQ) total score.

Results

Two main structures of narrative emplotment of FM illness were recognized: 1) the cumulative life narrative structure (46.15%) and 2) the broken life (53.85%) narrative structure. Baseline FIQ score was 77.38±7.77, and it was significantly reduced after PC to 39.12±13.27 (P<0.0001). Although well-being still requires further definition as outcome in pain management, it is important for FM patients, dealing with pain-related sensations, thoughts and feelings and limiting their daily activities. In our study, 87.5% of interviewed FM patients reported an improvement in their well-being after PC.

Conclusion

Our data suggest that an integrated PC program positively impacts chronic pain and fatigue based on self-management strategies. PC allows FM patients to resume their own life and regenerate their own image. Finally, we propose the introduction of the evaluation of the ability to resume daily activities as the target of rehabilitation programs in FM.

Exercise-induced hypoalgesia: A meta-analysis of exercise dosing for the treatment of chronic pain

OBJECTIVE

Increasing evidence purports exercise as a first-line therapeutic for the treatment of nearly all forms of chronic pain. However, knowledge of efficacious dosing respective to treatment modality and pain condition is virtually absent in the literature. The purpose of this analysis was to calculate the extent to which exercise treatment shows dose-dependent effects similar to what is seen with pharmacological treatments.

METHODS

A recently published comprehensive review of exercise and physical activity for chronic pain in adults was identified in May 2017. This report reviewed different physical activity and exercise interventions and their effectiveness in reducing pain severity and found overall modest effects of exercise in the treatment of pain. We analyzed this existing data set, focusing specifically on the dose of exercise intervention in these studies. We re-analyzed data from 75 studies looking at benefits of time of exercising per week, frequency of exercise per week, duration of intervention (in weeks), and estimated intensity of exercise.

RESULTS

Analysis revealed a significant positive correlation with exercise duration and analgesic effect on neck pain. Multiple linear regression modeling of these data predicted that increasing the frequency of exercise sessions per week is most likely to have a positive effect on chronic pain patients.

DISCUSSION

Modest effects were observed with one significant correlation between duration and pain effect for neck pain. Overall, these results provide insufficient evidence to conclude the presence of a strong dose effect of exercise in pain, but our modeling data provide tes predictions that can be used to design future studies to explicitly test the question of dose in specific patient populations.

Muscle pain induced by static contraction in rats is modulated by peripheral inflammatory mechanisms

Muscle pain is an important health issue and frequently related to static force exertion. The aim of this study is to evaluate whether peripheral inflammatory mechanisms are involved with static contraction-induced muscle pain in rats. To this end, we developed a model of muscle pain induced by static contraction performed by applying electrical pulses through electrodes inserted into muscle. We also evaluated the involvement of neutrophil migration, bradykinin, sympathetic amines and prostanoids. A single session of sustained static contraction of gastrocnemius muscle induced acute mechanical muscle hyperalgesia without affecting locomotor activity and with no evidence of structural damage in muscle tissue. Static contraction increased levels of creatine kinase but not lactate dehydrogenase, and induced neutrophil migration. Dexamethasone (glucocorticoid anti-inflammatory agent), DALBK (bradykinin B1 antagonist), Atenolol (β1 adrenoceptor antagonist), ICI 118,551 (β2 adrenoceptor antagonist), indomethacin (cyclooxygenase inhibitor), and fucoidan (non-specific selectin inhibitor) all reduced static contraction-induced muscle hyperalgesia; however, the bradykinin B2 antagonist, bradyzide, did not have an effect on static contraction-induced muscle hyperalgesia. Furthermore, an increased hyperalgesic response was observed when the selective bradykinin B1 agonist des-Arg⁹-bradykinin was injected into the previously stimulated muscle. Together, these findings demonstrate that static contraction induced mechanical muscle hyperalgesia in gastrocnemius muscle of rats is modulated through peripheral inflammatory mechanisms that are dependent on neutrophil migration, bradykinin, sympathetic amines and prostanoids. Considering the clinical relevance of muscle pain, we propose the present model of static contraction-induced mechanical muscle hyperalgesia as a useful tool for the study of mechanisms underlying static contraction-induced muscle pain.

The discordance between subjectively and objectively measured physical function in women with fibromyalgia: association with catastrophizing and self-efficacy cognitions. The al-Ándalus project

PURPOSE

People with fibromyalgia experience a disagreement between patient-reported (i.e., subjective) and performance-based (i.e., objective) status. This study aimed to (i) corroborate the discordance between subjectively and objectively measured physical function and (ii) examine whether catastrophizing (worrying, pain magnifying, and helpless cognitions) and self-efficacy (believing capable to manage pain) are independently associated with this discordance.

METHODS

This population-based cross-sectional study included 405 women with fibromyalgia and 193 age-matched female controls. Participants completed the Pain Catastrophizing Scale, Chronic Pain Self-efficacy Scale, and physical functioning subscales of the Revised Fibromyalgia Impact Questionnaire and Short Form-36 (SF-36) health survey. Objective physical function was measured with the Senior Fitness Test battery. Subjective and objective physical functions were expressed as deviation from the general population in standard deviation (SD) units using means and SD of the control group.

RESULTS

In fibromyalgia, subjective physical function was worse than objective physical function (p < 0.001). Higher catastrophizing was consistently associated with greater discordance between subjective and objective physical function, while self-efficacy was only significantly associated with this discordance when subjective physical function was assessed by means of the SF-36.

CONCLUSIONS

Subjective physical function is more impaired than objective physical function in fibromyalgia, yet both are markedly impaired. Catastrophizing cognitions are associated with this discordance. In particular, high catastrophizing may promote a feeling of reduced ability to do meaningful activities of daily living (i.e., restrictions) that people with fibromyalgia are actually able to. Therefore, catastrophizing should be assessed and potentially targeted when focusing on improving physical function in fibromyalgia. Implications for rehabilitation Rehabilitation should focus on physical exercise programs to help women with fibromyalgia to improve their reduced physical function. In rehabilitation settings, physical function of people with fibromyalgia should be evaluated by both subjective and objective assessments to fully understand physical functioning and to test the existence of discordance between both assessments. In case of a large discordance between subjective and objective physical function, a physical exercise program might be better complemented with cognitive management techniques to reduce catastrophizing and subjective physical dysfunction. When people with fibromyalgia experience high levels of catastrophizing, subjective assessments seem to be poor indicators of physical function.

Pain Response after Maximal Aerobic Exercise in Adolescents across Weight Status

INTRODUCTION

Pain reports are greater with increasing weight status, and exercise can reduce pain perception. It is unknown, however, whether exercise can relieve pain in adolescents of varying weight status. The purpose of this study was to determine whether adolescents across weight status report pain relief after high-intensity aerobic exercise (exercise-induced hypoalgesia (EIH)).

METHODS

Sixty-two adolescents (15.1 ± 1.8 yr, 29 males) participated in the following three sessions: 1) pressure pain thresholds (PPT) before and after quiet rest, clinical pain (McGill Pain Questionnaire), and physical activity levels (self-report and ActiSleep Plus Monitors) were measured, 2) PPT were measured with a computerized algometer at the fourth finger's nailbed, middle deltoid muscle, and quadriceps muscle before and after maximal oxygen uptake test (V˙O2max Bruce Treadmill Protocol), and 3) body composition was measured with dual-energy x-ray absorptiometry.

RESULTS

All adolescents met criteria for V˙O2max. On the basis of body mass index z-score, adolescents were categorized as having normal weight (n = 33) or being overweight/obese (n = 29). PPT increased after exercise (EIH) and were unchanged with quiet rest (trial × session, P = 0.02). EIH was similar across the three sites and between normal-weight and overweight/obese adolescents. Physical activity and clinical pain were not correlated with EIH. Overweight/obese adolescents had similar absolute V˙O2max (L·min(-1)) but lower relative V˙O2max (mL·kg(-1)·min(-1)) compared with normal-weight adolescents. When adolescents were categorized using FitnessGram standards as unfit (n = 15) and fit (n = 46), the EIH response was similar between fitness levels.

CONCLUSIONS

This study is the first to establish that both overweight and normal-weight adolescents experience EIH. EIH after high-intensity aerobic exercise was robust in adolescents regardless of weight status and not influenced by physical fitness.

Exercise Strengthens Central Nervous System Modulation of Pain in Fibromyalgia

To begin to elucidate the mechanisms underlying the benefits of exercise for chronic pain, we assessed the influence of exercise on brain responses to pain in fibromyalgia (FM). Complete data were collected for nine female FM patients and nine pain-free controls (CO) who underwent two functional neuroimaging scans, following exercise (EX) and following quiet rest (QR). Brain responses and pain ratings to noxious heat stimuli were compared within and between groups. For pain ratings, there was a significant (p < 0.05) Condition by Run interaction characterized by moderately lower pain ratings post EX compared to QR (d = 0.39–0.41) for FM but similar to ratings in CO (d = 0.10–0.26), thereby demonstrating that exercise decreased pain sensitivity in FM patients to a level that was analogous to pain-free controls. Brain responses demonstrated a significant within-group difference in FM patients, characterized by less brain activity bilaterally in the anterior insula following QR as compared to EX. There was also a significant Group by Condition interaction with FM patients showing less activity in the left dorsolateral prefrontal cortex following QR as compared to post-EX and CO following both conditions. These results suggest that exercise appeared to stimulate brain regions involved in descending pain inhibition in FM patients, decreasing their sensitivity to pain. Thus, exercise may benefit patients with FM via improving the functional capacity of the pain modulatory system.

A New Rehabilitation Tool in Fibromyalgia: The Effects of Perceptive Rehabilitation on Pain and Function in a Clinical Randomized Controlled Trial

Introduction/Objective. Fibromyalgia might benefit from a specific tactile and proprioceptive rehabilitation approach. The aim of this study was to perform a randomized controlled trial to determine the efficacy of perceptual surfaces (PS) and physical exercises with regard to chronic pain and physical function in fibromyalgia compared with a control group. Methods. Data from 54 females (18–60 years old) with a diagnosis of fibromyalgia and scoring >5 on the visual analog scale were divided into 3 groups and analyzed: group treated with perceptual surfaces (PS-group), physical exercises group (PE-group), and control group (CG). The Fibromyalgia Impact Questionnaire (FIQ), Health Assessment Questionnaire (HAQ), and Fibromyalgia Assessment Scale (FAS) were administered at baseline (T0), at the end of the treatment (T1) (after 10 rehabilitation sessions over a 5-week period), and at the 12-week follow-up (T2). Results. The PS-group experienced a statistically significant improvement versus the CG in FAS and HAQ scores. Good efficacy with respect to pain and function in the PE-group compared with the CG in terms of FAS, HAQ, and FIQ scores was observed. The adherence ratio was 86% for the PE-group and CG and 90% for the PS-group. Conclusions. According to the results, the PS are as promising as the physical exercises, since results were similar.