Periodontitis is associated with decreased experimental pressure pain tolerance: The Tromsø Study 2015-2016.

AIM: To assess the relationship between periodontitis and experimental pain tolerance. MATERIALS AND METHODS: Participants from the population-based seventh survey of the Tromsø Study with data on periodontitis were included (n = 3666, 40-84 years old, 51.6% women). Pain tolerance was assessed through (i) pressure pain tolerance (PPT) test with a computerized cuff pressure algometry on the leg, and (ii) cold-pressor tolerance (CPT) test where one hand was placed in circulating 3°C water. Cox proportional hazard regression was used to assess the association between periodontitis and pain tolerance adjusted for age, sex, education, smoking and obesity. RESULTS: In the fully adjusted model using the 2012 Centers for Disease Control/American Academy of Periodntology case definitions for surveillance of periodontitis, moderate (hazard ratio [HR] = 1.09; 95% confidence interval [CI]: 1.01, 1.18) and severe (HR = 1.25, 95% CI: 1.11, 1.42) periodontitis were associated with decreased PPT. Using the 2018 classification of periodontitis, having Stage II/III/IV periodontitis was significantly associated with decreased PPT (HR = 1.09; 95% CI: 1.01, 1.18) compared with having no or stage I periodontitis. There were no significant associations between periodontitis and CPT in fully adjusted models. CONCLUSIONS: Moderate and severe periodontitis was associated with experimental PPT.

Interaction between local blood flow and tolerance to prolonged pain in the elderly.

PURPOSE: We aimed to explore the link between local vasodilation and pain perception in elderly subjects, testing the hypothesis that altered local cutaneous blood flow participates in the decrease in pain tolerance with age. METHOD: Sixty-eight young and 83 older participants performed a pain tolerance test in which they hold their hand in an airtight box in which air temperature was regulated at 65 °C until the pain became unbearable. Participants continuously estimated pain intensity. Skin temperature and local blood flow in the box-exposed hand were continuously monitored. RESULTS: In the young group, 97% of subjects resisted pain until the end of the test, whereas only 53% in the elderly group managed to do so, indicating that pain tolerance is impaired in the elderly. Among all participants, the skin temperature associated with the first pain sensation was below the threshold for nociceptor activation (43 °C). Interestingly, blood flow in the elderly group was correlated with pain judgment, whereas no such correlation was observed in the young. CONCLUSION: Our results suggest that the local vasodilator response induced by local heating may be involved in pain perception and may influence thermal pain tolerance with aging. These results could contribute to a better understanding of vascular deficits and the development of chronic pain in vascular pathologies.

Blood flow restriction augments exercise-induced pressure pain thresholds over repetition and effort matched conditions.

We sought to determine the effects of blood flow restriction (BFR) on exercise-induced hypoalgesia, specifically using low-load (LL) resistance exercise (30% 1RM) protocols that accounted for each individual's local muscular endurance capabilities. Forty-four participants completed four conditions: (1) 70% of maximal BFR repetitions with blood flow restriction (LL+BFR exercise); (2) 70% maximal BFR repetitions without LL+BFR (LL exercise); (3) 70% maximal free flow repetitions (LL+EFFORT exercise); (4) time-matched, non-exercise control (CON). Pressure pain threshold (PPT) was measured before and after exercise. Ischaemic pain threshold and tolerance was assessed only at post. The change in upper body PPT was greater for LL+BFR exercise compared to LL exercise [difference of 0.15 (0.35) kg/cm2], LL+EFFORT exercise [difference of 0.23 (0.45) kg/cm2], and the CON condition. The change in lower body PPT was greater for LL+BFR exercise compared to LL exercise [difference of 0.40 (0.55) kg/cm2], LL+EFFORT exercise [difference of 0.36 (0.62) kg/cm2], and the CON condition. Ischaemic pain thresholds and tolerances did not change. Submaximal exercise with BFR resulted in systemic increases in PPT but had no influence on ischaemic pain sensitivity. This effect is likely unique to BFR as we did not see changes in the effort matched free flow condition.

Adversity type and timing predict temporal summation of pain in African-American adults.

African Americans are disproportionately exposed to adversity across the lifespan, which includes both stressful and traumatic events. Adversity, in turn, is associated with alterations in pain responsiveness. Racial differences in pain responsiveness among healthy adults are well established. However, the extent to which adversity type and timing are associated with alterations in pain responsiveness among healthy African-American adults is not well understood. The present study included 160 healthy African-American adults (98 women), ages 18 to 45. Outcome measures included pain tolerance and temporal summation of pain to evoked thermal pain. Composite scores were created for early-life adversity (childhood trauma, family adversity) and recent adversity (perceived stress, chronic stress burden). A measure of lifetime racial discrimination was also included. Higher levels of recent adversity were associated with higher temporal summation of pain, controlling for gender, age, and education. Neither early-life adversity nor lifetime racial discrimination were associated with temporal summation of pain. The present findings suggest that heightened temporal summation of pain among healthy African-American adults is associated with exposure to recent adversity events. Improved understanding of how recent adversity contributes to heightened temporal summation of pain in African Americans could help to mitigate racial disparities in pain experiences by identifying at-risk individuals who could benefit from early interventions.

Is your pain my pain? A study exploring the relation between pain sensitivity, pain thresholds and empathy for somatic and psychological pain.

OBJECTIVES: Research has shown that empathy for both somatic and psychological pain recruits affective components of the so-called pain matrix, a set of brain regions that is activated during the perception of somatic pain. In addition, the subjective evaluation of experimentally induced somatic pain is related to empathy for somatic pain. In contrast, it is unclear whether or not the subjective sensitivity to somatic pain impacts on empathy for psychological pain. METHODS: In the present study, 55 healthy participants conducted a pain-pressure-test (PPT) and a cold-pressor test (CPT) in order to assess pain thresholds, pain tolerance and evaluation of pain during the task. They further conducted the social interaction empathy task (SIET), which investigates empathy for somatic as well as psychological pain. All participants completed the interpersonal-reactivity index (IRI) and the pain-sensitivity questionnaire (PSQ). RESULTS: Participants who are in general more sensitive to somatic pain, as indicated by high-PSQ scores, showed higher empathy, that is, higher pain ratings, for both somatic and psychological painful situations observed in others as compared to those with low-PSQ scores. High-PSQ scores and high pain and unpleasantness ratings during the CPT were correlated with empathy for pain (both pain conditions), whereas pain thresholds (PPT) and pain tolerance thresholds (CPT) did not correlate with empathy. The IRI subscore 'personal distress' correlated with psychological pain ratings. CONCLUSIONS: Thus, empathy for both somatic and psychological pain were related to the subjective evaluation of somatic pain and general pain sensitivity.

Intraindividual change in pain tolerance and negative affect over 20 years: findings from the MIDUS study.

Pain tolerance, defined as the ability to withstand physical pain states, is a clinically important psychobiological process associated with several deleterious outcomes, including increased pain experience, mental health problems, physical health problems, and substance use. A significant body of experimental work indicates that negative affect is associated with pain tolerance, such that increased negative affect is associated with decreased pain tolerance. Although research has documented the associations between pain tolerance and negative affect, little work has examined these associations over time, and how change in pain tolerance is related to changes in negative affect. Therefore, the current study examined the relationship between intraindividual change in self-reported pain tolerance and intraindividual change in negative affect over 20 years in a large, longitudinal, observation-based national sample of adults (n = 4,665, Mage = 46.78, SD =12.50, 53.8% female). Results from parallel process latent growth curve models indicated that slope of pain tolerance and negative affect were associated with each other over time (r = .272, 95% CI [.08, .46] p = .006). Cohen's d effect size estimates provide initial, correlational evidence that changes in pain tolerance may precede changes in negative affect. Given the relevance of pain tolerance to deleterious health outcomes, better understanding how individual difference factors, including negative affect, influence pain tolerance over time, are clinically important to reduce disease-related burden.

The Negative Effect of Social Discrimination on Pain Tolerance and the Moderating Role of Pain Catastrophizing.

This study examined the negative impact of social discrimination on the time to pain tolerance during experimentally induced cold pressor pain among healthy individuals. It was hypothesized that the degree to which one catastrophized about pain would exacerbate the negative impact of a history discriminatory experiences on pain tolerance, and that this interaction would be different between individuals of a racial and ethnic minority and non-Hispanic white individuals (thus testing catastrophizing as a moderated moderator). Higher levels of discrimination were positively related to catastrophic thinking about pain, and there was a significant negative relationship between the level of experienced discrimination and time to pain tolerance. Pain catastrophizing emerged as a significant moderator in that when pain catastrophizing levels were high, there was no association between social discrimination and pain tolerance. A history of social discrimination was significantly associated with reduced pain tolerance at low and moderate levels of pain catastrophizing. Racial minority status did not significantly alter this moderating relationship. Implications for the importance of assessing sociocultural variables, such as experiencing social discrimination in the clinical assessment of the individual with pain are outlined.

Effectiveness of spontaneous pain coping strategies for acute pain management: A laboratory study.

The aim of the present study has been to analyze the relationship between the use of not previously trained, diverse acute pain coping strategies and levels of pain intensity and pain tolerance in a group of healthy participants. Previous research has analyzed the usefulness of the training of these strategies after several training sessions, but adequate patient training requires a great deal of time. Two hundred and forty healthy people participated in the study. Pain coping strategies was evaluated with a version of CSQ-S. Subsequently, the participants completed a cold pressor test and tolerance test. After that, subjects filled in the adaptation of the CSQ-S about the strategies which they had employed throughout the test. Correlation analyses showed a positive relationship between pain intensity and catastrophizing, distractor behaviors, hoping and ignoring the pain. Pain tolerance correlated with self-instructions, ignoring the pain, reinterpreting the pain, catastrophizing and faith and praying. Regression analyses showed that catastrophizing was found to be the strategy that most predicts the variance of pain intensity, and catastrophizing (negative) and ignoring the pain (positive) and praying (negative) were the most predictive ones for pain tolerance. This is the first laboratory study that identifies the more useful pain coping strategies which can be used by patients without previous training in an acute pain context. The results of this study could be useful in the development of protocols for nurses and other health professionals, especially for situations where potentially painful techniques are to be applied to patients.

"No pain, no gain": The impact of autonomous sensory meridian response on pain perception.

Autonomous sensory meridian response (ASMR) is a phenomenon characterised by a static-like tingling sensation spreading from the scalp and neck to the periphery in response to a variety of audio, visual, and tactile triggers resulting in a highly relaxed state and boosted positive affect. The limited literature on this phenomenon points to a potential of ASMR to alleviate pain. Emerging evidence also suggests that ASMR may be linked to increased sensory sensitivity more broadly. This study aimed to objectively address these claims by administering an algometer (measure of pain tolerance), and a visual analog scale (VAS) (measure of subjective pain sensitivity) to ASMR experiencers and controls at baseline, following an ASMR video, and a control video. Findings indicate that ASMR experiencers have a higher pain sensitivity than controls; however, there was no difference between the two groups in terms of pain tolerance. In addition, any potential analgesic properties associated with experiencing ASMR may reflect protective properties of ASMR buffering against the increased pain sensitivity among ASMR experiencers relative to controls.

Blunted Pain Modulation Response to Induced Stress in Women with Fibromyalgia with and without Posttraumatic Stress Disorder Comorbidity: New Evidence of Hypo-Reactivity to Stress in Fibromyalgia?

There is evidence regarding the presence of alterations in both the stress response and the endogenous pain modulation systems of people with fibromyalgia (FM). However, research on pain modulation under induced stress on FM patients is scarce and contradictory. The present study analyzes stress-induced changes in pain and intolerance thresholds among FM patients, examining the possible existence of differences linked to PTSD comorbidity and gaining insights into the role of cardiovascular reactivity. Eighteen women diagnosed with FM and comorbid PTSD (FM + PTSD), 18 women diagnosed with FM and no PTSD (FM-PTSD), and 38 healthy women (HC) were exposed to the Social Stress Test task. Pressure pain thresholds and intolerance thresholds were measured before and during stress induction, and after a recovery period, while systolic blood pressure and heart rate were simultaneously recorded. Overall, while pain thresholds decreased during stress and recovery for HC, no significant changes were observed for women with FM. The intolerance threshold decreased for HC during stress, but was maintained at basal level during recovery. FM-PTSD women exhibited a delayed response, with a drop at recovery. For FM + PTSD, tolerance levels remained unchanged. In addition, cardiovascular reactivity did not seem to explain these results. This performance of the pain modulation system seems to follow the same pattern of hypoactive responsiveness under stressors that has previously been observed in FM patients on the autonomic and neuroendocrine axes. Such a hypoactive pattern may involve a non-adaptive response that may contribute to the development and maintenance of chronic pain.

Are all pain tolerance tasks the same? Convergent validity of four behavioral pain tolerance tasks, self-reported capability for suicide, and lifetime self-injurious behaviors.

OBJECTIVES: Discrepancies persist regarding the extent to which different pain measures provide similar information and relate to capability for suicide and self-injurious behaviors. This study examined pain threshold, tolerance, and persistence across four modalities (cold, heat, pressure, shock) and assessed associations with self-reported capability for suicide, non-suicidal self-injury (NSSI), and suicide attempts. METHODS: A sample of 211 students who reported lifetime suicidal ideation completed four behavioral pain tasks and self-reported on capability for suicide, NSSI, and self-injurious behaviors. RESULTS: All pain thresholds, tolerances, and persistences were positively correlated across the four tasks. Pain facets were related to self-reported capability for suicide with small effect sizes but generally did not differ across suicide attempt or NSSI histories. CONCLUSIONS: Pain thresholds, tolerances, and persistences demonstrated convergent validity across the four modalities, suggesting that these tasks provide similar information. Although the relation between pain and self-injurious behaviors remains unclear, these tasks can generally be used interchangeably.

Mental pain intensity and tolerance as predictors of psychotherapy process and outcome.

BACKGROUND: The extensive reliance on symptoms for the study of psychotherapy is often criticized. In this study we examined whether the subjective sense of mental pain predicts psychotherapy process and outcome, above and beyond the effect of symptomatic distress. METHODS: Outpatients (n = 53) treated in a psychiatric hospital completed measures of mental pain intensity and tolerance, symptomatic distress, and session climate at pretreatment and posttreatment. Multilevel modeling was utilized to assess the predictive effect of mental pain, while controlling baseline symptomatic distress. RESULTS: Patients with high mental pain at baseline showed significant reductions in distress, while patients with low mental pain showed no significant improvement. Moreover, low mental pain and high mental pain tolerance predicted decreases in session smoothness. CONCLUSIONS: Mental pain can serve as a predictive marker for psychotherapy process and outcome, and complement the reliance on symptomatic distress in psychotherapy research.

Is the relationship between child abuse and suicide attempts mediated by nonsuicidal self-injury and pain tolerance?

Although there is evidence for an association of child abuse with lifetime suicidal behaviour, the underlying mechanisms remain unclear. In recent research, we found this relationship to be indirect and mediated by capability for suicide (CS). Emotional and sexual abuse were directly associated with CS. Based on the Interpersonal Psychological Theory of Suicide, the result for emotional abuse was surprising and raised the question for a missing link in this association. Consequently, this study examines nonsuicidal self-injury (NSSI) as an additional mediator (M1 ) between child abuse (X), pain tolerance (M2 ), and suicide attempts (Y). We included 308 psychiatric inpatients (M = 36.9 years, 53% female) with either an acute suicidal crisis (n = 146) or a recent suicide attempt (n = 157). For the assessment, we used the Childhood Trauma Screener (CTS), the German version of the self-injurious thoughts and behaviours interview (SITBI-G), the German Capability for Suicide Questionnaire (GCSQ), and a pressure algometer for measuring pain tolerance objectively. Serial mediator analyses were applied. All types of abuse showed relationships with NSSI, which itself was connected to suicidal behaviour in almost all models, whereas pain tolerance did not show the expected relations. The results suggest that NSSI is an important predictor for suicide attempts and should be considered in suicide risk assessment. Future research should address this topic in prospective studies with a more comprehensive assessment of child abuse. In summary, this study once again highlights the serious effects of child abuse and in particular the mediating role of NSSI.

A comparison of low dose ultrasound and far-infrared therapies in patients with mechanical neck pain.

OBJECTIVE: To compare the effect of low-dose continuous ultrasound and far-infrared interventions for reducing pain in patients with mechanical neck pain. Methods: The experimental study was conducted from April 2016 to January 2017 at the electrotherapy laboratory of the Department of Physical Therapy, College of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia, and comprised female patients diagnosed with mechanical neck pain. They were divided into two equal groups, with Group A receiving 3 sessions per week of low-dose continuous ultrasound on the cervical region for 7 weeks, and Group B receiving far-infrared treatment on the same patterns. Both groups received stretching, strengthening exercises and transcutaneous electrical nerve stimulation. Pain tolerance was assessed at baseline and post-intervention using digital algometer. Data was analysed using SPSS 17. RESULTS: Of the 30 women with a mean age of 21.36±1.14 years, there were 15(50%) in each of the two groups. There was a significant decrease in post-intervention bilateral values compared to baseline in both groups. Group B showed higher significant values than Group A (p<0.05). CONCLUSIONS: Far-Infrared was found to be much better than low-dose continuous ultrasound for reducing pain in patients suffering from mechanical neck pain.

Validation of the German capability for suicide questionnaire (GCSQ) in a high-risk sample of suicidal inpatients.

BACKGROUND: The German Capability for Suicide Questionnaire (GCSQ) was developed to measure fearlessness of death and pain tolerance - two constructs central to the Interpersonal Theory of Suicide. Initial scale development, definition of the factor structure and confirmation of the two-dimensional factor structure was performed in samples suffering from relatively low levels of suicide ideation/behavior. The present study aimed to validate the German Capability for Suicide Questionnaire (GCSQ) in a high-risk sample of suicidal inpatients. METHODS: Factor structure, reliability and validity were investigated in a sample of inpatients (N = 296; 53.0% female; age in years: M = 36.81, SD = 14.27) admitted to a hospital due to a recent suicide attempt or an acute suicidal crisis (in immediate need of inpatient treatment). To establish convergent validity, interview-based assessments of lifetime suicide attempts and non-suicidal self-injury as well as questionnaire-based assessments of painful and provocative events were used. Finally, stability of GCSQ-scores over a follow-up period of 12 months was assessed. RESULTS: Results indicated good psychometric properties, and provided additional evidence for construct validity and stability of the subscales over a one-year period, and demonstrated adequate fit of the data with respect to the original factor structure. CONCLUSIONS: Results suggest that the GCSQ is a brief, reliable, and valid measure of capability for suicide that can be used in clinic assessment and research.

Essential oil inhaler (AromaStick®) improves heat tolerance in the Hot Immersion Test (HIT). Results from two randomized, controlled experiments.

BACKGROUND: A recent review article on an aromatherapeutic inhaler demonstrated clinical effects on a number of bodily systems, like the cardiovascular system, the respiratory system, the nervous system and the endocrine system. OBJECTIVE: This paper extends these findings and investigates whether specially designed essential oils inhalers are capable to counter experimentally induced stressful heat sensations. METHOD: Two prospective, randomized, controlled experiments using the Hot Immersion Test Paradigm (HIT) were conducted to investigate whether deep odor inhalations increase heat tolerance. RESULTS: In both experiments, the inhaler strongly prolonged pain tolerance and increased blood oxygenation (1 < d < 1.3). In the second experiment, the inhaler also increased heart rate variability (d = 1.3) as a mechanism to cope with heat stress. CONCLUSION: The ability to resist a stressful thermal stimulus can be exogenously improved by short and deep inhalations of essential scents directly delivered to the olfactory system.

Kratom and Pain Tolerance: A Randomized, Placebo-Controlled, Double-Blind Study.

Background: Kratom has a long history of traditional medicine use in Southeast Asia. Consumption of kratom products has also been reported in the US and other regions of the world. Pain relief is among many self-reported kratom effects but have not been evaluated in controlled human subject research. Methods: Kratom effects on pain tolerance were assessed in a randomized, placebo-controlled, double-blind study. During a 1-day inpatient stay, participants received a randomized sequence of kratom and placebo decoctions matched for taste and appearance. Pain tolerance was measured objectively in a cold pressor task (CPT) as time (seconds) between the pain onset and the hand withdrawal from the ice bath. Health status, vital signs, objective, and subjective indicators of withdrawal symptoms, self-reported data on lifetime kratom use patterns, and assessments of blinding procedures were also evaluated. Results: Twenty-six males with the mean (SD) age 24.3 (3.4) years were enrolled. They reported the mean (SD) 6.1 (3.2) years of daily kratom consumption. Pain tolerance increased significantly 1 hour after kratom ingestion from the mean (SD) 11.2 (6.7) seconds immediately before to 24.9 (39.4) seconds 1 hour after kratom consumption (F(2,53.7)=4.33, p=0.02). Pain tolerance was unchanged after consuming placebo drinks: 15.0 (19.0) seconds immediately before and 12.0 (8.1) seconds 1 hour after consumption of placebo (F(2,52.8)=0.93, p=0.40). No discomfort or signs of withdrawal were reported or observed during 10-20 hours of kratom discontinuation. Conclusions: Kratom decoction demonstrated a substantial and statistically significant increase in pain tolerance. Further rigorous research on kratom pain-relieving properties and a safety profile is needed.

Interoceptive deficits, non-suicidal self-injury, and suicide risk: a multi-sample study of indirect effects.

BACKGROUND: Interoceptive deficits (ID) have been associated with non-suicidal self-injury (NSSI) and suicidal behavior in multiple studies. Many of these studies are limited in scope, and have not fully examined possible mechanisms explaining how ID affect suicidal behavior. METHODS: This study assesses how self-reported ID relate to suicide ideation and attempts in six distinct and geographically diverse samples of adults (n = 2706) and one sample of adolescents (n = 436). Participants responded to a variety of self-report questionnaires and interviews. RESULTS: Contrary to our hypothesis, self-reported ID were only associated with suicidal ideation in two samples, one of which was the adolescent sample. Largely consistent with our predictions, self-reported ID exhibited an indirect effect on suicide attempts through versatility of NSSI in four of the five adult samples tested. Finally, the indirect effects of self-reported ID on suicide attempts through NSSI versatility did not act indirectly through behaviorally assessed pain tolerance. CONCLUSIONS: We found that, in adults, self-reported ID are not associated with suicidal ideation, but are connected with a history of suicide attempts, through an indirect effect via NSSI. Our findings also indicate that the mechanism of action leading from self-reported ID to suicidal behavior may differ between adolescents and adults, and relate to suicidal behavior independent of pain tolerance. Clinical implications and future directions are discussed.

Attention-deficit/hyperactivity disorder medication does not alter exercise-induced hypoalgesia following an acute bout of dynamic circuit resistance exercise.

The primary goal of this study was to investigate the effects of attention-deficit/hyperactivity disorder (ADHD) medications on exercise-induced hypoalgesia (EIH), heart rate, and perceived exertion. Thirty college-age students (10 Controls, 10 ADHD diagnosis, and 10 ADHD diagnosis with medications) completed 2 sessions: 1) a maximal testing session and 2) an experimental session consisting of 3 consecutive dynamic resistance exercise circuits comprised of 12 repetitions of 9 exercises at 60% of 1-repetition maximum using a 1:1 work to rest ratio. All participants, regardless of condition (Controls vs. ADHD without medications vs. ADHD with medications), displayed EIH accompanied by an increase in blood lactate, heart rate, and perceived exertion for the duration of the exercise bout. Therefore, the effects of resistance exercise are not altered by ADHD diagnosis or psychostimulant medication use for ADHD. These findings are intriguing given the known ergogenic and hypoalgesic effects of caffeine, a less potent stimulant.

Responses to Slowly Repeated Evoked Pain Stimuli in Fibromyalgia Patients: Evidence of Enhanced Pain Sensitization.

OBJECTIVE: The pathophysiology of fibromyalgia has been related to central pain sensitization. This study tested a laboratory protocol evaluating responses to slowly repeated evoked pain stimuli (SREP) that may index central pain sensitization in fibromyalgia. DESIGN: A between-subjects controlled laboratory study. SUBJECTS: Twenty-four fibromyalgia patients and 24 healthy participants. METHODS: A SREP protocol was administered to all subjects, consisting of a single series of nine low-intensity pressure stimuli of five-second duration and thirty-second interstimulus interval. Subjective evoked pain intensity was assessed with a visual analogical scale. Clinical fibromyalgia pain was assessed with the McGill Pain Questionnaire. RESULTS: Perceived pain intensity increased during the SREP protocol in fibromyalgia patients but not in healthy participants. Neither pain threshold nor pain tolerance was associated with SREP. Degree of SREP sensitization was associated with McGill Pain Questionnaire-Sensory ratings of fibromyalgia pain. The effect size for differences between the fibromyalgia and healthy control groups was greater, and the overlaps of the groups distributions lower, for SREP sensitization than for traditional evoked pain measures of pain threshold and tolerance. SREP demonstrated higher specificity in discriminating fibromyalgia and control groups relative to pain threshold or tolerance. CONCLUSIONS: A protocol employing a single series of nine low-suprathreshold-intensity slowly repeated pain stimuli elicits increased perceived pain in fibromyalgia patients, consistent with central sensitization despite relatively long interstimulus intervals. SREP appears to be more useful than traditional evoked pain threshold tolerance measures in terms of predicting levels of clinical pain and discriminating between fibromyalgia patients and healthy individuals.