Cold Pressor Pain Threshold Research Articles

Swearing as a Response to Pain: Assessing Hypoalgesic Effects of Novel "Swear" Words.

Previous research showing that swearing alleviates pain is extended by addressing emotion arousal and distraction as possible mechanisms. We assessed the effects of a conventional swear word (“fuck”) and two new “swear” words identified as both emotion-arousing and distracting: “fouch” and “twizpipe.” A mixed sex group of participants (N = 92) completed a repeated measures experimental design augmented by mediation analysis. The independent variable was repeating one of four different words: “fuck” vs. “fouch” vs. “twizpipe” vs. a neutral word. The dependent variables were emotion rating, humor rating, distraction rating, cold pressor pain threshold, cold pressor pain tolerance, pain perception score, and change from resting heart rate. Mediation analyses were conducted for emotion, humor, and distraction ratings. For conventional swearing (“fuck”), confirmatory analyses found a 32% increase in pain threshold and a 33% increase in pain tolerance, accompanied by increased ratings for emotion, humor, and distraction, relative to the neutral word condition. The new “swear” words, “fouch” and “twizpipe,” were rated as more emotional and humorous than the neutral word but did not affect pain threshold or tolerance. Changes in heart rate and pain perception were absent. Our data replicate previous findings that repeating a swear word at a steady pace and volume benefits pain tolerance, extending this finding to pain threshold. Mediation analyses did not identify a pathway via which such effects manifest. Distraction appears to be of little importance but emotion arousal is worthy of future study.

Assessing peripheral fibers, pain sensitivity, central sensitization, and descending inhibition in Native Americans: main findings from the Oklahoma Study of Native American Pain Risk.

Native Americans (NAs) have a higher prevalence of chronic pain than other U.S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Multiple pain stimulus modalities were used (eg, cold, heat, pressure, ischemic, and electric), and subjective (eg, pain ratings and pain tolerance) and physiological (eg, nociceptive flexion reflex) outcomes were measured. There were no group differences on any measure, except that NAs had lower cold-pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA pain risk.

An Experimental Investigation of the Effect of Age and Sex/Gender on Pain Sensitivity in Healthy Human Participants

Background: Ageing is associated with alterations of the structure and function of somatosensory tissue that can impact on pain perception. The aim of this study was to investigate the relationship between age and pain sensitivity responses to noxious thermal and mechanical stimuli in healthy adults. Methods: 56 unpaid volunteers (28 women) aged between 20 and 55 years were categorised according to age into one of seven possible groups. The following measurements were taken: thermal detection thresholds, heat pain threshold and tolerance using a TSA-II NeuroSensory Analyzer; pressure pain threshold using a handheld electronic pressure algometer; and cold pressor pain threshold, tolerance, intensity and unpleasantness. Results: There was a positive correlation between heat pain tolerance and age (r = 0.228, P = 0.046), but no statistically significant differences between age groups for cold or warm detection thresholds, or heat pain threshold or tolerance. Forward regression found increasing age to be a predictor of increased pressure pain threshold (B = 0.378, P = 0.002), and sex/gender to be a predictor of cold pressor pain tolerance, with women having lower tolerance than men (B = -0.332, P = 0.006). Conclusion: The findings of this experimental study provide further evidence that pressure pain threshold increases with age and that women have lower thresholds and tolerances to innocuous and noxious thermal stimuli. Significance: The findings demonstrate that variations in pain sensitivity response to experimental stimuli in adults vary according to stimulus modality, age and sex and gender.

Evaluation of Relationship Between Body Mass Index and Experimental Pain Responses in a Young Population In Northern Nigeria

Pain perception has been shown to differ between patients with different gender, race and culture. In addition, it has been suggested that obesity influences pain perception, and can be a risk factor for increase pain perception later in life. The aim of this study was to investigate the relationship between obesity and pain perception among a young population in Zaria, Northern Nigeria. One hundred and thirty-two (132) apparently healthy subjects between the ages of 12 to 20 years were assessed for pain using the cold pressor test and ischemic pain models. Subjects also filled a self-reported questionnaire on physical activity. Data were presented as mean ± SD. Differences and statistical significance between the means was determined by t-test for sex differences, while effect of BMI on pain responses was analyzed using ANOVA. Values of p ≤ 0.05 were considered significant. Result of this study showed that obese subjects had a significantly lower cold pressor pain threshold than non-obese subjects, but no statistically significant difference was observed on cold pressor pain tolerance. Ischemic pain response on the other hand, showed no statistically significant variation between all the groups tested. The study indicates that there is a relationship between obesity and pain perception among a young Nigerian population in Zaria, Nigeria.

Relationship between Serum Methadone Concentration and Cold Pressor Pain Sensitivity in Patients Undergoing Methadone Maintenance Therapy.

Hyperalgesia is a common clinical phenomenon among opioid dependent patients on methadone maintenance therapy (MMT) and it may be associated with undertreated pain and/or therapeutic failure. This study aimed to investigate association between serum methadone concentration (SMC) and cold pressor pain responses. Cold pressor pain responses in 147 opioid dependent patients on MMT were assessed using cold pressor test (CPT) at 0 h and at 2, 4, 8, 12, and 24 h after the dose intake. Blood samples were collected at 24 h after the dose. Serum methadone concentrations were measured using the Methadone ELISA kit and classified into two categories: < 400 ng/mL and ≥ 400 ng/mL. Eighty-eight patients (59.9%) had trough concentrations of < 400 ng/mL and 40.1% had trough concentrations of ≥ 400 ng/mL. There were significant effects of SMC on the cold pressor pain threshold (p = 0.019). Patients with concentrations < 400 ng/mL had significantly higher (almost 60% higher) cold pressor pain threshold (adjusted mean (95% CI) = 30.15 (24.29, 36.01) s) compared to those with concentrations of ≥ 400 ng/mL (18.93 (11.77, 26.08) seconds). There was also a 20% difference in pain tolerance, and 6% difference in cold pressor pain intensity score, neither of which were significant statistically (p > 0.05). Our results suggest an association of trough methadone concentration with the cold pressor pain threshold among opioid dependent patients on MMT. It would be useful to study the mechanisms underlying this association to help managing pain in such a population.

Body mass index and distribution of body fat can influence sensory detection and pain sensitivity.

The aim of this study was to investigate the influence of body fat percentage and its distribution on sensory detection and pain sensitivity responses to experimentally induced noxious stimuli in otherwise pain-free individuals. Seventy-two participants were divided into three equal groups according to their body mass index (BMI: normal, overweight and obese). Percentage body fat was estimated using a four-site skinfold method. Measurements of cold pressor pain threshold, tolerance and intensity; contact thermal sensory detection and heat pain threshold and tolerance (TSA-II - NeuroSensory Analyzer, Medoc); and blunt pressure pain threshold (algometer, Somedic SenseLab AB) were taken at the waist and thenar eminence. Mean±SD pressure pain threshold of the obese group (620.72±423.81 kPa) was significantly lower than normal (1154.70±847.18 kPa) and overweight (1285.14±998.89 kPa) groups. Repeated measures ANOVA found significant effects for site for cold detection threshold (F1,68 =8.3, p=0.005) and warm detection threshold (F1,68 =38.69, p=0.001) with waist having lower sensory detection thresholds than thenar eminence. For heat pain threshold, there were significant effects for site (F1,68 =4.868, p=0.031) which was lower for waist compared with thenar eminence (mean difference=0.89°C). Obese individuals were more sensitive than non-obese individuals to pressure pain but not to thermal pain. Body sites may vary in their response to different types and intensities of stimuli. The inconsistency of findings within and between research studies should catalyse further research in this field. This study provided evidence that body mass index and distribution of body fat can influence sensory detection and pain sensitivity. Obese individuals were more sensitive than normal range body mass index individuals to pressure pain but not to thermal pain. Pain response varied according to subcutaneous body fat at different body sites. These findings strengthen arguments that weight loss should be a significant aspect of a pain management programme for obese pain patients.

Does Fentanyl Lead to Opioid-induced Hyperalgesia in Healthy Volunteers?: A Double-blind, Randomized, Crossover Trial.

Although opioids in general and remifentanil in particular have been shown to induce hyperalgesia, data regarding fentanyl are scarce. Thus, the authors investigated the effect of fentanyl dosing on pain perception and central sensitization in healthy volunteers using established pain models. Twenty-one healthy, male volunteers were included in this randomized, double-blind, crossover study and received either intravenous low-dose (1 μg/kg) or high-dose (10 μg/kg) fentanyl. Pain intensities and hyperalgesia were assessed by intracutaneous electrical stimulation, and cold pressor pain was used as an additional measure of acute pain. The primary outcome was hyperalgesia from 4.5 to 6.5 h after fentanyl administration. A higher dose of fentanyl led to significantly decreased pain scores as measured by the numeric rating scale (0.83 units lower [95% CI, 0.63 to 1.02]; P < 0.001) but increased areas of hyperalgesia (+30.5% [95% CI, 16.6 to 44.4%]; P < 0.001) from 4.5 to 6.5 h after fentanyl administration. Allodynia did not differ between groups (+4.0% [95% CI, -15.4 to 23.5%]; P = 0.682).The high dose also led to both increased cold pressor pain threshold (+43.0% [95% CI, 29.7 to 56.3%]; P < 0.001) and tolerance (+32.5% [95% CI, 21.7 to 43.4%]; P < 0.001) at 4.5 to 6.5h. In the high-dose group, 19 volunteers (90%) required reminders to breathe, 8 (38%) required supplemental oxygen, and 12 (57%) experienced nausea. A higher dose of fentanyl increased hyperalgesia from 4.5 to 6.5 h in healthy volunteers while simultaneously decreasing pain scores.

Striatal μ-opioid receptor availability predicts cold pressor pain threshold in healthy human subjects

Previous PET studies in healthy humans have shown that brain μ-opioid receptor activation during experimental pain is associated with reductions in the sensory and affective ratings of the individual pain experience. The aim of this study was to find out whether brain μ-opioid receptor binding at the resting state, in absence of painful stimulation, can be a long-term predictor of experimental pain sensitivity. We measured μ-opioid receptor binding potential (BPND) with μ-opioid receptor selective radiotracer [11C]carfentanil and positron emission tomography (PET) in 12 healthy male subjects. Later, we recruited these subjects to participate in a separate psychophysical testing session to measure cold pressor pain threshold, cold pressor pain tolerance and tactile sensitivity with von Frey monofilaments. We used both voxel-by-voxel and region-of-interest image analyses to examine the potential associations between μ-opioid receptor BPND and psychophysical measures. The results show that striatal μ-opioid receptor BPND predicts cold pressor pain threshold, but not cold pressor pain tolerance or tactile sensitivity. This finding suggests that striatal μ-opioid receptor density is involved in setting individual pain threshold.

Pain sensitivity and opioid analgesia: A pharmacogenomic twin study

Opioids are the cornerstone medication for the management of moderate to severe pain. Unfortunately, vast inter-individual differences in dose requirements complicate their effective and safe clinical use. Mechanisms underlying such differences are incompletely understood, are likely multifactorial, and include genetic and environmental contributions. While accumulating evidence suggests that variants of several genes account for some of the observed response variance, the relative contribution of these factors remains unknown. This study used a twin paradigm to provide a global estimate of the genetic and environmental contributions to inter-individual differences in pain sensitivity and analgesic opioid effects. Eighty one monozygotic and 31 dizygotic twin pairs successfully underwent a computer-controlled infusion with the μ-opioid agonist alfentanil in a single occasion, randomized, double-blind and placebo-controlled study design. Pain sensitivity and analgesic effects were assessed with experimental heat and cold pressor pain models along with important covariates including demographic factors, depression, anxiety, and sleep quality. Significant heritability was detected for cold pressor pain tolerance and opioid-mediated elevations in heat and cold pressor pain thresholds. Genetic effects accounted for 12–60% of the observed response variance. Significant familial effects accounting for 24–32% of observed variance were detected for heat and cold pressor pain thresholds and opioid-mediated elevation in cold pressor pain tolerance. Significant covariates included age, gender, race, education, and anxiety. Results provide a strong rationale for more detailed molecular genetic studies to elucidate mechanisms underlying inter-individual differences in pain sensitivity and analgesic opioid responses. Such studies will require careful consideration of the studied pain phenotype.

Comparison of post-treatment effects of conventional and acupuncture-like transcutaneous electrical nerve stimulation (TENS): A randomised placebo-controlled study using cold-induced pain and healthy human participants

TENS can be administered in conventional (high frequency, low intensity) or acupuncture-like (AL-TENS: low frequency, high intensity) formats. It is claimed that AL-TENS produces stronger and longer-lasting hypoalgesia than conventional TENS, although evidence is lacking. This randomised controlled parallel group study compared the effects of 30 minutes of AL-TENS, conventional TENS, and placebo (no current) TENS, on cold-pressor pain threshold (CPT), in 43 healthy participants. Results showed a greater increase in mean loge cold-pressor pain threshold relative to baseline for both AL-TENS and conventional TENS vs. placebo TENS, and for AL-TENS vs. placebo 5 and 15 minutes after TENS was switched off. There were no statistically significant differences between conventional TENS vs. placebo or between AL-TENS vs. conventional TENS at 5 or 15 minutes after TENS was switched off. In conclusion, AL-TENS but not conventional TENS prolonged post-stimulation hypoalgesia compared to placebo TENS. However, no differences between AL-TENS and conventional TENS were detected in head-to-head comparisons.

Conventional versus acupuncture‐like transcutaneous electrical nerve stimulation on cold‐induced pain in healthy human participants: effects during stimulation

To compare the hypoalgesic effects of conventional transcutaneous electrical nerve stimulation (TENS) (high frequency, low intensity) and acupuncture-like TENS (AL-TENS, low frequency, high intensity) on cold-induced pain. Randomized controlled parallel group study comparing the effects of strong non-painful AL-TENS, conventional TENS and placebo (no current) TENS on cold-pressor pain threshold (CPT) and pain intensity. Two baseline (pre-intervention) measures and three during intervention measures of CPT and cold pain intensity (four point category scale) were recorded. Physiology laboratory in Leeds Metropolitan University. One hundred and twenty-one healthy participants. Each participant received one of three TENS interventions over their flexor digitorum profundus: (i) high pulse rate TENS with a strong non-painful paraesthesia (conventional), (ii) low-rate burst mode TENS that caused strong non-painful phasic muscle twitching (acupuncture like) or (iii) no current (placebo) TENS. Difference between conventional TENS and AL-TENS in cold pain threshold relative to pre-TENS baseline after 25 min of stimulation. No differences were detected for CPT or cold pain intensity during conventional TENS compared with AL-TENS. When compared with placebo TENS, the confidence intervals for the ratio of intervention CPT to baseline CPT, for both AL-TENS (0·966, 1·424) and conventional TENS (0·948, 1·401), were close to the positive side of one, although neither reached statistical significance. Unlike some previous studies, the present study detected no differences in hypoalgesia between AL-TENS, conventional TENS and placebo (no current) TENS during stimulation.

Gabapentin improves cold-pressor pain responses in methadone-maintained patients

Individuals on methadone maintenance for the treatment of addiction (MM) are demonstrated to be hyperalgesic to cold-pressor pain in comparison to matched controls and ex-opioid addicts, a finding described as clinical evidence of opioid-induced hyperalgesia (OIH). Interestingly, opioids induce hyperalgesia via many of the same neuro-inflammatory and central sensitization processes that occur with the development of neuropathic pain. Evaluated in this study was the efficacy of a key pharmacotherapy for neuropathic pain, gabapentin (GPN), to reverse OIH in MM patients. Utilizing a clinical trial design and double blind conditions, changes in cold-pressor pain threshold and tolerance following a 5-week trial of GPN (titrated to 2400 mg/day) were evaluated at peak and trough methadone plasma levels in a well-characterized MM sample. Drug abstinence was encouraged via an escalating payment schedule, and compliance monitored via pill counts and GPN plasma levels; entered into the analyses were only those subjects compliant and abstinent throughout the study (approximately 45%). Utilizing change scores from baseline, significant improvements in cold-pressor pain threshold and pain tolerance were observed at both peak and trough methadone levels ( p < 0.05). Notably, drop-out rates due to medication side effects were low (2%) and the medication was well-tolerated. These results support that GPN, as prescribed for the treatment of neuropathic pain, is effective in decreasing OIH in patients who are abstinent and stable in methadone treatment.

Alexithymia in fibromyalgia syndrome: Associations with ongoing pain, experimental pain sensitivity and illness behavior

ObjectiveAlexithymia, a lack of emotional awareness, is common in chronic pain patients. The aim of the study was to investigate the relationship of alexithymia to ongoing pain, experimental pain sensitivity, and illness behavior in patients with chronic musculoskeletal pain. MethodsSixty-eight women with fibromyalgia (age: average, 43.4 years; range, 19–72 years) completed self-report measures on alexithymia (20-Item Toronto Alexithymia Scale), ongoing pain [Visual Analogue Scale, Questionario Italiano del Dolore (QUID), Margolis], psychological distress (Center for Epidemiology Studies—Depression Scale, State–Trait Anxiety Inventory Form Y), and illness behavior (Illness Behavior Questionnaire). Psychophysical tests were performed to assess experimental pain sensitivity, including pain thresholds for mechanical (von Frey, tender point count) and thermal (heat, cold) stimuli, and cold pressor pain threshold and tolerance. ResultsAlexithymia “difficulty identifying feelings” (DIF) was related to higher ratings of the affective—but not the sensory—dimensions of ongoing pain (QUID) and to a lower cold pressor pain tolerance, while alexithymia scores were independent of all pain thresholds. Multiple regression demonstrated that alexithymia DIF ceased to uniquely predict affective ongoing pain when psychological distress or illness behavior was separately controlled for. Higher alexithymia DIF scores were predictive of hypochondriacal illness behavior, over and above what was explained by psychological distress and affective pain. ConclusionAlexithymia is associated with increased affective pain and hypochondriacal illness behavior. The former relationship is better explained, and possibly mediated, by psychological distress and illness behavior. The hypothesis of a generally increased sensitivity to unpleasant stimuli in alexithymic chronic pain patients is not supported by the data.

CLINICAL STUDY: Lack of effect of chronic dextromethorphan on experimental pain tolerance in methadone‐maintained patients

Good evidence exists to suggest that individuals on opioid maintenance for the treatment of addiction (i.e. methadone) are less tolerant of experimental pain than are matched controls or ex-opioid addicts, a phenomenon theorized to reflect opioid-induced hyperalgesia (OIH). Agonist activity at the excitatory ionotropic N-methyl-D-aspartate (NMDA) receptor on dorsal horn neurons has been implicated in the development of both OIH and its putative expression at the clinical level-opioid tolerance. The aim of this study was to evaluate the potential utility of the NMDA-receptor antagonist, dextromethorphan (DEX), to reverse or treat OIH in methadone-maintenance (MM) patients. Utilizing a clinical trial design and double-blind conditions, changes in pain threshold and tolerance [cold pressor (CP) and electrical stimulation (ES)] following a 5-week trial of DEX (titrated to 480 mg/day) in comparison with placebo was evaluated in a well-characterized sample of MM patients. The sample (n = 40) was 53% male and ethnically diverse (53% Latino, 28% African American, 10% White, 9% other), with a mean age of 48.0 years (SD = 6.97). Based on t-test analyses, no difference was found between groups on CP pain threshold, CP pain tolerance, ES pain threshold or ES pain tolerance, both pre- and postmedication. Notably, DEX-related changes significantly differed by gender, with women tending to show diminished tolerance for pain with DEX therapy. These results support that chronic high-dose NMDA antagonism does not improve tolerance for pain in MM patients, although a gender effect on DEX response is suggested.

Correlation of human cold pressor pain responses with 5-HT 1A receptor binding in the brain

We determined whether serotonin 5-HT 1A receptor availability in the brain is associated with cold pressor pain (CPP) or sympathetic reflex responses. Psychophysical testing was performed in eleven healthy males who had participated in a positron emission tomography study with [ carbonyl- 11C]WAY-100635 ligand for the assessment of 5-HT 1A receptor binding potential (BP). Psychophysical testing consisted of determining CPP threshold, tolerance, intensity, unpleasantness and CPP threshold modulation by conditioning CPP. Autonomic control was assessed by determining the cutaneous vasoconstriction responses in the finger induced by CPP and Valsalva maneuver. CPP intensity was inversely correlated with 5-HT 1A BP in multiple cortical and subcortical areas, including the prefrontal and cingulate cortices, insula, amygdala and the dorsal raphe. CPP unpleasantness was not significantly correlated with 5-HT 1A BP in any of the regions of interest. Increase of CPP threshold by conditioning CPP was directly correlated with 5-HT 1A BP in the amygdala and medial prefrontal cortex. Vasoconstriction induced by Valsalva but not CPP was directly correlated with 5-HT 1A BP in the ventral part of the anterior cingulate cortex and the anterior insula. The results suggest that 5-HT 1A receptors in the brain influence pain and Valsalva-induced sympathetic vasoconstriction reflex. In general, subjects with high availability of 5-HT 1A receptors have low CPP intensity accompanied by a high capacity for central suppression of pain or a sympathetic vasoconstriction response by a Valsalva maneuver.

Ethnic differences in responses to multiple experimental pain stimuli

A growing body of literature suggests that the experience of clinical pain differs across ethnocultural groups. Additionally, some evidence indicates greater sensitivity to experimentally induced pain among African Americans; however, most studies have included only one pain modality. This study examined ethnic differences in responses to multiple experimental pain stimuli, including heat pain, cold pressor pain, and ischemic pain. Heat pain threshold and tolerance, ratings of repetitive suprathreshold heat, and ischemic and cold pressor pain threshold and tolerance were assessed in 120 (62 African American, 58 white) healthy young adults. Also, several psychological instruments were administered. No ethnic group differences emerged for threshold measures, but African Americans had lower tolerances for heat pain, cold pressor pain and ischemic pain compared to whites. Ratings of intensity and unpleasantness for suprathreshold heat stimuli were significantly higher among African Americans. African Americans reported greater use of passive pain coping strategies and higher levels of hypervigilance. Controlling for passive pain coping did not account for group differences in pain responses, while controlling for hypervigilance rendered group differences in heat pain tolerance and ischemic pain tolerance non-significant. These findings demonstrate differences in laboratory pain responses between African Americans and whites across multiple stimulus modalities, and effect sizes for these differences in pain tolerance were moderate to large for suprathreshold measures. Hypervigilance partly accounted for group differences. Additional research to determine the mechanisms underlying these effects is warranted.

Withdrawal hyperalgesia after acute opioid physical dependence in nonaddicted humans: a preliminary study

Hyperalgesia has been demonstrated to be a cardinal sign of physical withdrawal from opioids in preclinical models for more than 30 years, although few empirical data exist to support its occurrence in humans. In this preliminary study we used the acute opioid physical dependence (APD) model to test for the presence of hyperalgesia to experimental cold-pressor pain in 4 healthy non–opioid-dependent men via 3 different pretreatment opioid administration protocols previously demonstrated to induce APD (morphine 18 mg/70 kg intramuscular, morphine 10 mg/70 kg intravenous, hydromorphone 2 mg/70 kg intravenous), repeated on 2 separate occasions, and placebo. Cold-pressor pain threshold and tolerance were examined before opioid administration and 5 and 15 minutes after precipitated withdrawal with naloxone 10 mg/70 kg intravenous. Paired t tests comparing change scores between the opioid pretreatments and placebo showed that pain threshold and tolerance to the cold-pressor uniformly decreased across all APD induction methods, and the effect size was large (∼70% of baseline) and reproducible. These findings provide initial support for the existence of opioid-induced hyperalgesia, which has been conceptualized as a coexisting opponent process to opioid-induced analgesia and proposed to be an alternative explanation for the development of analgesic tolerance to opioids.

The analgesic effects of interferential (IF) current on cold-pressor pain in healthy subjects: a single blind trial of three IF currents against sham IF and control

Interferential (IF) therapy is well documented as a therapeutic medium for pain relief. Despite widespread use by physiotherapists, there remains very limited laboratory or clinical evidence for the analgesic effect of IF.Fifty volunteers were randomly allocated to one of five groups ( n =10): control group (no treatment throughout); IF 100 Hz applied to the ipsilateral limb; IF 100 Hz applied to the contralateral limb; IF 30 Hz applied to the ipsilateral limb; Sham IF applied to the ipsilateral limb. Subjects were given repeated (six) cycles of cold-pressor pain and pain threshold scores were recorded for each cycle and compared using repeated measure ANOVA. Mean pain threshold values for all groups increased with the exception of the control group: where pain threshold values decreased across the cycles. Pain thresholds within IF treatment groups repeatedly increased, but no more than sham IF. IF at 30 Hz and 100 Hz applied to the contralateral limb offered more consistency in the rise in mean values, with the sham group demonstrating more variation in performance. However, statistical analysis failed to show any significant differences for the treatment effects either within groups across repeated cycles (P=0.123) or between the groups across cycles (P=0.552). IF does not significantly alter pain threshold.

The influence of athletic status and gender on experimental pain responses

Abstract: To examine the role of athletic status and gender on experimental pain responses, 24 athletes (12 male, 12 female) and 24 nonathletes (12 male, 12 female) participated in 3 experimental pain tasks. After a series of psychologic inventories and demographic questionnaires, pressure pain thresholds (4 sites: pectoralis, trapezius, biceps, quadriceps), ischemic pain threshold and tolerance (lower arm), and cold pressor pain threshold and tolerance (lower arm) were assessed. No significant overall effects of athletic status or gender were identified for measures of pressure pain threshold. No group differences emerged for ischemic pain threshold. Athletes demonstrated significantly higher tolerance for ischemic pain, and cold pressor pain threshold and tolerance were higher among athletes than nonathletes. Overall analyses indicated higher pain thresholds and tolerance for cold pain among men than among women. A final interview found that many participants who approached the upper limits of these pain tasks reported using a competitive coping strategy. [copy ] 2002 by the American Pain Society

Experimentally induced anger, cardiovascular reactivity, and pain sensitivity

It was investigated whether an angry state, induced by a computer task with harassing comments, would lead to a decrease in cold pressor pain threshold and tolerance in comparison to a neutral situation. It was hypothesized that an increase in cardiovascular activity might partially mediate effects of anger. Furthermore, it was examined whether subjects given the opportunity to express anger would show reduced cardiovascular activity and pain report compared to subjects not given this opportunity. Finally, trait measures for anger expression style and hostility were included. The results show an increase instead of the expected decrease in pain tolerance for subjects in the harassment condition compared to those in the neutral condition. While cardiovascular reactivity was positively related to pain threshold and tolerance, increased anger was associated with increased pain report. It is suggested that anger and cardiovascular reactivity may have important but sometimes opposing influences on pain.