Are endogenous opioid mechanisms involved in the effects of aerobic exercise training on chronic low back pain? A randomized controlled trial

Through the Lens of Movement-Evoked Pain: A Theoretical Framework of the "Pain-Movement Interface" to Guide Research and Clinical Care for Musculoskeletal Pain Conditions

Over 120 million Americans report experiencing pain in the past 3 months. Among these individuals, 50 million report chronic pain and 17 million report pain that limits daily life or work activities on most days (ie, high-impact chronic pain). Musculoskeletal pain conditions in particular are a major contributor to global disability, health care costs, and poor quality of life. Movement-evoked pain (MEP) is an important and distinct component of the musculoskeletal pain experience and represents an emerging area of study in pain and rehabilitation fields. This focus article proposes the "Pain-Movement Interface" as a theoretical framework of MEP that highlights the interface between MEP, pain interference, and activity engagement. The goal of the framework is to expand knowledge about MEP by guiding scientific inquiry into MEP-specific pathways to disability, high-risk clinical phenotypes, and underlying individual influences that may serve as treatment targets. This framework reinforces the dynamic nature of MEP within the context of activity engagement, participation in life and social roles, and the broader pain experience. Recommendations for MEP evaluation, encompassing the spectrum from high standardization to high patient specificity, and MEP-targeted treatments are provided. Overall, the proposed framework and recommendations reflect the current state of science in this emerging area of study and are intended to support future efforts to optimize musculoskeletal pain management and enhance patient outcomes. PERSPECTIVE: Movement-evoked pain (MEP) is a distinct component of the musculoskeletal pain experience and emerging research area. This article introduces the "Pain-Movement Interface" as a theoretical framework of MEP, highlighting the interface between MEP, pain interference, and activity engagement. Evaluating and treating MEP could improve rehabilitation approaches and enhance patient outcomes.

Exercise as Medicine for People with a Substance Use Disorder: An ACSM Call to Action Statement

ABSTRACT

Over 20 million Americans are living with a substance use disorder (SUD) and nearly 100,000 die annually from drug overdoses, with a majority involving an opioid. Many people with SUD have co-occurring chronic pain and/or a mental health disorder. Exercise is a frontline treatment for chronic pain and is an effective strategy for reducing depression and anxiety and improving overall mental health. Several studies have shown that exercise improves SUD-related outcomes including abstinence; however, there is limited large-scale randomized clinical trial evidence to inform integration of exercise into practice. In this Call to Action, we aim to raise awareness of the specific issues that should be addressed to advance exercise as medicine in people with SUD including the challenges of co-occurring chronic pain, mental illness, and cardiopulmonary health conditions. In addition, specialized training for exercise professionals and other support staff should be provided on these issues, as well as on the multiple dimensions of stigma that can impair engagement in treatment and overall recovery in people with SUD.

Physical activity, sitting time, and thermal quantitative sensory testing responses in African Americans

Introduction

Prior research suggests that African Americans (AAs) have more frequent, intense, and debilitating pain and functional disability compared with non-Hispanic Whites (NHWs). Potential contributing factors to this disparity are physical activity and sedentary behavior, given that AAs are less physically active, and physical activity is associated with antinociception (whereas sedentary behavior is linked to pronociception). However, impact of these factors on pain processing has largely been unexplored in AAs, especially before chronic pain onset.

Objective

This study examined relationships between physical activity, sedentary behavior (sitting time), and laboratory measures of pain and pain modulation in adult AAs. These included heat pain threshold and tolerance, temporal summation of pain (TSP, a marker of central sensitization), and conditioned pain modulation (CPM, a marker of descending pain inhibition).

Methods

Multiple regressions were conducted to examine the effects of physical activity and sitting time on heat threshold and tolerance. Multilevel models were conducted to assess the relationship between physical activity, sitting time, and temporal summation of pain. Additional multilevel models were conducted to assess the relationship between physical activity, sitting time, and conditioned pain modulation.

Results

Higher level of physical activity, but not sitting time, was associated with reduced TSP slopes. Neither physical activity nor sitting time was associated with CPM slopes. No significant relationships between physical activity or sitting time and heat pain threshold or tolerance were detected.

Conclusions

These findings suggest that physical activity is associated with reduced TSP, an effect which may be driven by reduced spinal hyperexcitability in more active individuals. Thus, structural and individual interventions designed to increase physical activity in healthy, young AAs may be able to promote antinociceptive processes (ie, reduced TSP/reduced pain facilitation) potentially protective against chronic pain.

Systematic Review to Inform a World Health Organization (WHO) Clinical Practice Guideline: Benefits and Harms of Structured Exercise Programs for Chronic Primary Low Back Pain in Adults

PURPOSE

Evaluate benefits and harms of structured exercise programs for chronic primary low back pain (CPLBP) in adults to inform a World Health Organization (WHO) standard clinical guideline.

METHODS

We searched for randomized controlled trials (RCTs) in electronic databases (inception to 17 May 2022). Eligible RCTs targeted structured exercise programs compared to placebo/sham, usual care, or no intervention (including comparison interventions where the attributable effect of exercise could be isolated). We extracted outcomes, appraised risk of bias, conducted meta-analyses where appropriate, and assessed certainty of evidence using GRADE.

RESULTS

We screened 2503 records (after initial screening through Cochrane RCT Classifier and Cochrane Crowd) and 398 full text RCTs. Thirteen RCTs rated with overall low or unclear risk of bias were synthesized. Assessing individual exercise types (predominantly very low certainty evidence), pain reduction was associated with aerobic exercise and Pilates vs. no intervention, and motor control exercise vs. sham. Improved function was associated with mixed exercise vs. usual care, and Pilates vs. no intervention. Temporary increased minor pain was associated with mixed exercise vs. no intervention, and yoga vs. usual care. Little to no difference was found for other comparisons and outcomes. When pooling exercise types, exercise vs. no intervention probably reduces pain in adults (8 RCTs, SMD = - 0.33, 95% CI - 0.58 to - 0.08) and functional limitations in adults and older adults (8 RCTs, SMD = - 0.31, 95% CI - 0.57 to - 0.05) (moderate certainty evidence).

CONCLUSIONS

With moderate certainty, structured exercise programs probably reduce pain and functional limitations in adults and older people with CPLBP.

Dosage of Physical Activity to Avoid Impairment of Activities Due to Pain: Analysis of Population-based Conditional Processes

BACKGROUND

Physical activity's established health benefits include pain control, yet there is no consensus on the required dosage according to the literature.

AIM

To test the influence of exercise on perceived health in patients whose daily activities are limited due to pain. Besides, analyze the possible moderating effect of age and find a formula for exercise dosage based on the perceived level of health.

METHODS

Cross-sectional study based on the 2017 Spanish National Health Survey with 4,123 participants reporting activity limitations in their daily activities due to pain. The International Physical Activity Questionnaire (short version) was used to calculate energy expenditure. Data included age, sex, leisure-time physical activity, sitting time, pain-related impairments, pain medication, and perceived health. Mediation regression analysis was conducted using the SPSS PROCESS 4.0 macro.

RESULTS

Results indicate a decline in perceived health with age. The relationship between exercise (energy expenditure) and perceived health was highly significant (d=-0.224, p<0.001). Age moderated the association between pain and energy expenditure up to 75.61 years (0.1568, p=0.05) and between energy expenditure and perceived health up to 75.74 years (-0.289, p=0.05), but this effect diminished afterwards. A formula was developed to estimate energy expenditure based on the desired level of health.

CONCLUSIONS

The perception of health in people who are limited in their daily activities due to pain (moderate to very much) is mediated by the amount of physical activity they perform. Besides, this perception is moderated by age, up to 76 years.

Higher intensity exercise reduces disability more than lower intensity exercise in adults with chronic low back pain: A systematic review and meta-analysis

BACKGROUND

Intensity is an important determinant of physiological adaptations and health benefits of exercise, but the role of exercise intensity on improving outcomes in people with chronic low back pain (CLBP) is unclear. This systematic review aimed to determine the effect of higher versus lower intensity exercise intensity on pain, disability, quality of life and adverse events in people with CLBP.

METHODS

Six databases and four clinical trial registries were searched from inception to 21 December 2022, for randomised controlled trials that compared two or more exercise intensities in adults with CLBP. Data were analysed using random-effects meta-analysis for disability and synthesised narratively for pain, quality of life and adverse events due to limited studies. Risk of bias was assessed using the Cochrane tool and certainty of evidence was evaluated using Grading of Recommendations, Assessment, Development and Evaluations framework.

RESULTS

Four trials (n = 214 participants, 84% male) reported across five studies were included. Higher intensity exercise reduced disability more than lower intensity exercise at end-treatment (SMD [95% CI] = -0.39 [-0.56 to -0.22]; very low certainty) but not at 6-month follow-up (SMD [95% CI] = -0.20 [-0.53 to 0.13]; very low certainty). Higher intensity exercise did not reliably improve pain and quality of life more than lower intensity exercise. Adverse events did not differ between exercise intensities. All studies were at high risk of bias.

CONCLUSION

Based on very low certainty evidence from a limited number of studies, exercise intensity does not appear to meaningfully influence clinical outcomes in people with CLBP.

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

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

Aerobic Fitness Is Associated with Cerebral μ-Opioid Receptor Activation in Healthy Humans

INTRODUCTION

Central μ-opioid receptors (MORs) modulate affective responses to physical exercise. Individuals with higher aerobic fitness report greater exercise-induced mood improvements than those with lower fitness, but the link between cardiorespiratory fitness and the MOR system remains unresolved. Here we tested whether maximal oxygen uptake (V̇O2peak) and physical activity level are associated with cerebral MOR availability and whether these phenotypes predict endogenous opioid release after a session of exercise.

METHODS

We studied 64 healthy lean men who performed a maximal incremental cycling test for V̇O2peak determination, completed a questionnaire assessing moderate-to-vigorous physical activity (MVPA; in minutes per week), and underwent positron emission tomography with [11C]carfentanil, a specific radioligand for MOR. A subset of 24 subjects underwent additional positron emission tomography scan also after a 1-h session of moderate-intensity exercise and 12 of them also after a bout of high-intensity interval training.

RESULTS

Higher self-reported MVPA level predicted greater opioid release after high-intensity interval training, and both V̇O2peak and MVPA level were associated with a larger decrease in cerebral MOR binding after aerobic exercise in the ventral striatum, orbitofrontal cortex, and insula. That is, more trained individuals showed greater opioid release acutely after exercise in brain regions especially relevant for reward and cognitive processing. Fitness was not associated with MOR availability.

CONCLUSIONS

We conclude that regular exercise training and higher aerobic fitness may induce neuroadaptation within the MOR system, which might contribute to improved emotional and behavioral responses associated with long-term exercise.

Advances in targeting central sensitization and brain plasticity in chronic pain

Maladaptation in sensory neural plasticity of nociceptive pathways is associated with various types of chronic pain through central sensitization and remodeling of brain connectivity. Within this context, extensive research has been conducted to evaluate the mechanisms and efficacy of certain non-pharmacological pain treatment modalities. These include neurostimulation, virtual reality, cognitive therapy and rehabilitation. Here, we summarize the involved mechanisms and review novel findings in relation to nociceptive desensitization and modulation of plasticity for the management of intractable chronic pain and prevention of acute-to-chronic pain transition.

Stress-induced analgesia: an evaluation of effects on temporal summation of pain and the role of endogenous opioid mechanisms

Acute stress reduced the initial pain rating in a temporal summation protocol via nonopioid mechanisms but did not affect temporal summation slope, an indicator of central sensitization.

Introduction:

Objectives:

Methods:

Results:

Conclusions:

Does aerobic exercise effect pain sensitisation in individuals with musculoskeletal pain? A systematic review

Background

Pain sensitisation plays a major role in musculoskeletal pain. However, effective treatments are limited, and although there is growing evidence that exercise may improve pain sensitisation, the amount and type of exercise remains unclear. This systematic review examines the evidence for an effect of aerobic exercise on pain sensitisation in musculoskeletal conditions.

Methods

Systematic searches of six electronic databases were conducted. Studies were included if they examined the relationship between aerobic physical activity and pain sensitisation in individuals with chronic musculoskeletal pain, but excluding specific patient subgroups such as fibromyalgia. Risk of bias was assessed using Cochrane methods and a qualitative analysis was conducted.

Results

Eleven studies (seven repeated measures studies and four clinical trials) of 590 participants were included. Eight studies had low to moderate risk of bias. All 11 studies found that aerobic exercise increased pressure pain thresholds or decreased pain ratings in those with musculoskeletal pain [median (minimum, maximum) improvement in pain sensitisation: 10.6% (2.2%, 24.1%)]. In these studies, the aerobic exercise involved walking or cycling, performed at a submaximal intensity but with incremental increases, for a 4-60 min duration. Improvement in pain sensitisation occurred after one session in the observational studies and after 2-12 weeks in the clinical trials.

Conclusions

These findings provide evidence that aerobic exercise reduces pain sensitisation in individuals with musculoskeletal pain. Further work is needed to determine whether this translates to improved patient outcomes, including reduced disability and greater quality of life.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05047-9.

Choosing what works for whom: towards a better use of mechanistic knowledge in clinical practice

BACKGROUND

Clinicians commonly try to use mechanism-based knowledge to make sense of the complexity and uncertainty of chronic pain treatments to create a rationale for their clinical decision-making. Although this seems intuitive, there are some problems with this approach.

DISCUSSION

The widespread use of mechanism-based knowledge in clinical practice can be a source of confusion for clinicians, especially when complex interventions with different proposed mechanisms of action are equally effective. Although the available mechanistic evidence is still of very poor quality, in choosing from various treatment options for people with chronic pain, an approach that correctly incorporates mechanistic reasoning might aid clinical thinking and practice.

CONCLUSION

By explaining that not all evidence of mechanism is the same and by making a proposal to start using mechanism-based knowledge in clinical practice properly, we hope to help clinicians to incorporate mechanistic reasoning to prioritize and start choosing what may best work for whom.

Interventions for the Management of Acute and Chronic Low Back Pain: Revision 2021

Low back pain (LBP) remains a musculoskeletal condition with an adverse societal impact. Globally, LBP is highly prevalent and a leading cause of disability. This is an update to the 2012 Academy of Orthopaedic Physical Therapy (AOPT), formerly the Orthopaedic Section of the American Physical Therapy Association (APTA), clinical practice guideline (CPG) for LBP. The overall objective of this update was to provide recommendations on interventions delivered by physical therapists or studied in care settings that included physical therapy providers. It also focused on synthesizing new evidence, with the purpose of making recommendations for specific nonpharmacologic treatments. J Orthop Sports Phys Ther 2021;51(11):CPG1-CPG60. doi:10.2519/jospt.2021.0304.

Exercise therapy for chronic low back pain

BACKGROUND

Low back pain has been the leading cause of disability globally for at least the past three decades and results in enormous direct healthcare and lost productivity costs.

OBJECTIVES

The primary objective of this systematic review is to assess the impact of exercise treatment on pain and functional limitations in adults with chronic non-specific low back pain compared to no treatment, usual care, placebo and other conservative treatments.

SEARCH METHODS

We searched CENTRAL (which includes the Cochrane Back and Neck trials register), MEDLINE, Embase, CINAHL, PsycINFO, PEDro, SPORTDiscus, and trials registries (ClinicalTrials.gov and World Health Organization International Clinical Trials Registry Platform), and conducted citation searching of relevant systematic reviews to identify additional studies. The review includes data for trials identified in searches up to 27 April 2018. All eligible trials have been identified through searches to 7 December 2020, but have not yet been extracted; these trials will be integrated in the next update.

SELECTION CRITERIA

We included randomised controlled trials that assessed exercise treatment compared to no treatment, usual care, placebo or other conservative treatment on the outcomes of pain or functional limitations for a population of adult participants with chronic non-specific low back pain of more than 12 weeks' duration.

DATA COLLECTION AND ANALYSIS

Two authors screened and assessed studies independently, with consensus. We extracted outcome data using electronic databases; pain and functional limitations outcomes were re-scaled to 0 to 100 points for meta-analyses where 0 is no pain or functional limitations. We assessed risk of bias using the Cochrane risk of bias (RoB) tool and used GRADE to evaluate the overall certainty of the evidence. When required, we contacted study authors to obtain missing data. To interpret meta-analysis results, we considered a 15-point difference in pain and a 10-point difference in functional limitations outcomes to be clinically important for the primary comparison of exercise versus no treatment, usual care or placebo.

MAIN RESULTS

We included 249 trials of exercise treatment, including studies conducted in Europe (122 studies), Asia (38 studies), North America (33 studies), and the Middle East (24 studies). Sixty-one per cent of studies (151 trials) examined the effectiveness of two or more different types of exercise treatment, and 57% (142 trials) compared exercise treatment to a non-exercise comparison treatment. Study participants had a mean age of 43.7 years and, on average, 59% of study populations were female. Most of the trials were judged to be at risk of bias, including 79% at risk of performance bias due to difficulty blinding exercise treatments. We found moderate-certainty evidence that exercise treatment is more effective for treatment of chronic low back pain compared to no treatment, usual care or placebo comparisons for pain outcomes at earliest follow-up (MD -15.2, 95% CI -18.3 to -12.2), a clinically important difference. Certainty of evidence was downgraded mainly due to heterogeneity. For the same comparison, there was moderate-certainty evidence for functional limitations outcomes (MD -6.8 (95% CI -8.3 to -5.3); this finding did not meet our prespecified threshold for minimal clinically important difference. Certainty of evidence was downgraded mainly due to some evidence of publication bias.  Compared to all other investigated conservative treatments, exercise treatment was found to have improved pain (MD -9.1, 95% CI -12.6 to -5.6) and functional limitations outcomes (MD -4.1, 95% CI -6.0 to -2.2). These effects did not meet our prespecified threshold for clinically important difference. Subgroup analysis of pain outcomes suggested that exercise treatment is probably more effective than education alone (MD -12.2, 95% CI -19.4 to -5.0) or non-exercise physical therapy (MD -10.4, 95% CI -15.2 to -5.6), but with no differences observed for manual therapy (MD 1.0, 95% CI -3.1 to 5.1). In studies that reported adverse effects (86 studies), one or more adverse effects were reported in 37 of 112 exercise groups (33%) and 12 of 42 comparison groups (29%). Twelve included studies reported measuring adverse effects in a systematic way, with a median of 0.14 (IQR 0.01 to 0.57) per participant in the exercise groups (mostly minor harms, e.g. muscle soreness), and 0.12 (IQR 0.02 to 0.32) in comparison groups.

AUTHORS' CONCLUSIONS

We found moderate-certainty evidence that exercise is probably effective for treatment of chronic low back pain compared to no treatment, usual care or placebo for pain. The observed treatment effect for the exercise compared to no treatment, usual care or placebo comparisons is small for functional limitations, not meeting our threshold for minimal clinically important difference. We also found exercise to have improved pain (low-certainty evidence) and functional limitations outcomes (moderate-certainty evidence) compared to other conservative treatments; however, these effects were small and not clinically important when considering all comparisons together. Subgroup analysis suggested that exercise treatment is probably more effective than advice or education alone, or electrotherapy, but with no differences observed for manual therapy treatments.

Does aerobic exercise training alter responses to opioid analgesics in individuals with chronic low back pain? A randomized controlled trial

ABSTRACT

We tested whether aerobic exercise training altered morphine analgesic responses or reduced morphine dosages necessary for adequate analgesia. Patients with chronic back pain were randomized to an 18-session aerobic exercise intervention (n = 38) or usual activity control (n = 45). Before and after the intervention, participants underwent 3 laboratory sessions (double-blinded, crossover) to assess effects of saline placebo, i.v. morphine (0.09 mg/kg), and i.v. naloxone (12 mg) on low back pain and evoked heat pain responses. Differences in evoked and back pain measures between the placebo and morphine conditions indexed morphine analgesia, with pre-post intervention changes the primary outcome. Endogenous opioid analgesia was indexed by differences in evoked and low back pain measures between the naloxone and placebo conditions. A Sex X Intervention interaction on the analgesic effects of morphine on visual analogue scale back pain intensity was observed (P = 0.046), with a similar trend for evoked pain threshold (P = 0.093). Male exercisers showed reduced morphine analgesia pre-post intervention, whereas male controls showed increased analgesia (with no differences in females). Of clinical significance were findings that relative to the control group, aerobic exercise produced analgesia more similar to that observed after receiving ≈7 mg morphine preintervention (P < 0.045). Greater pre-post intervention increases in endogenous opioid function (from any source) were significantly associated with larger pre-post intervention decreases in morphine analgesia (P < 0.046). The overall pattern of findings suggests that regular aerobic exercise has limited direct effects on morphine responsiveness, reducing morphine analgesia in males only.

Clinical guidelines and care pathway for management of low back pain with or without radicular pain

OBJECTIVE

To develop guidelines for low back pain management according to previous international guidelines and the updated literature.

METHODS

A report was compiled from a review of systematic reviews of guidelines published between 2013 and 2018 and meta-analysis of the management of low back pain published between 2015 and 2018. This report summarized the state-of-the-art scientific knowledge for each predefined area of the guidelines from a critical review of selected literature. A multidisciplinary panel of experts including 17 health professionals involved in low back pain management and 2 patient representatives formulated preliminary guidelines based on the compilation report and a care pathway. The compilation report and preliminary guidelines were submitted to 25 academic institutions and stakeholders for the consultation phase. From responses of academic institutions and stakeholders, the final guidelines were developed. For each area of the guidelines, agreement between experts was assessed by the RAND/UCLA method.

RESULTS

The expert panel drafted 32 preliminary recommendations including a care pathway, which was amended after academic institution and stakeholder consultation. The consensus of the multidisciplinary expert panel was assessed for each final guideline: 32 recommendations were assessed as appropriate; none was assessed as uncertain or inappropriate. Strong approval was obtained for 27 recommendations and weak for 5.

CONCLUSION

These new guidelines introduce several concepts, including the need to early identify low back pain at risk of chronicity to provide quicker intensive and multidisciplinary management if necessary.

Slowly repeated evoked pain (SREP) as a central sensitization marker in episodic migraine patients

Migraine headache is a pain condition characterized by severe and recurrent unilateral head pain. Among other mechanisms, central pain sensitization processes seem to be involved in the disorder. An experimental protocol based on slowly repeated evoked pain (SREP) has been shown to indicate pain sensitization in fibromyalgia patients and differentiate these patients from healthy individuals and rheumatoid arthritis patients. This study examined SREP sensitization in migraine patients and explored its potential usefulness as a central sensitization marker. The SREP protocol was administered to 40 episodic migraine (EM) patients not currently experiencing a headache and 40 healthy controls. SREP consisted of a series of 9 suprathreshold painful pressure stimuli of 5 s duration and a 30 s interstimulus interval. SREP sensitization was indexed by the increase in pain ratings across the stimuli. Pain threshold, pain tolerance and temporal summation of pain were also assessed. SREP sensitization was observed in EM, but not in healthy individuals (p < .001). SREP differentiated between EM and healthy individuals with up to 75% diagnostic accuracy. Pain threshold, pain tolerance and temporal summation of pain did not show significant discriminative ability. An SREP index value of 0.5 was the most sensitive cut-off for detecting central pain sensitization when prioritizing diagnostic sensitivity (0.88). Results provide evidence for SREP as a possible central sensitization marker with potential clinical utility in migraine patients. Inclusion of SREP in Quantitative Sensory Testing protocols may enhance the assessment of altered pain modulation in different pain conditions.