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Abstract

Over the past 20 years a number of studies have examined whether analgesia occurs following exercise. Exercise involving running and cycling have been examined most often in human research, with swimming examined most often in animal research. Pain thresholds and pain tolerances have been found to increase following exercise. In addition, the intensity of a given pain stimulus has been rated lower following exercise. There have been a number of different noxious stimuli used in the laboratory to produce pain, and it appears that analgesia following exercise is found more consistently for studies that used electrical or pressure stimuli to produce pain, and less consistently in studies that used temperature to produce pain. There is also limited research indicating that analgesia can occur following resistance exercise and isometric exercise. Currently, the mechanism(s) responsible for exercise-induced analgesia are poorly understood. Although involvement of the endogenous opioid system has received mixed support in human research, results from animal research seem to indicate that there are multiple analgesia systems, including opioid and non-opioid systems. It appears from animal research that properties of the exercise stressor are important in determining which analgesic system is activated during exercise.
... Physical exercise is recommended as a treatment to CNLBP [5], since exercise activates endogenous analgesia pathways [6] of healthy people or patients with CNLBP [7]. Regarding healthy people, pain-free individuals, an acute exercise session results in a period of hypoalgesia known as exercise induced hypoalgesia (EIH) [8]. EIH is usually assessed by pressure pain thresholds (PPT) measured before and after an exercise session [9]. ...
... The mechanisms responsible for EIH are not fully understood. Human research shows controversial results [8], while animal studies showed that opioid hypothesis is more consistent. However, EIH can also occur through activation of the endocannabinoid, serotoninergic, immune, autonomic nervous system, and conditioned pain modulation systems [8,10,13,30]. ...
... Human research shows controversial results [8], while animal studies showed that opioid hypothesis is more consistent. However, EIH can also occur through activation of the endocannabinoid, serotoninergic, immune, autonomic nervous system, and conditioned pain modulation systems [8,10,13,30]. In populations with chronic pain, this phenomenon may be impaired in some people, and may remain unchanged or even have hyperalgesia in response to exercise. ...
... In healthy, pain-free populations and also in patients suffering from chronic pain, physical activity can lead to exercise-induced hypoalgesia (EIH) (Vaegter and Jones 2020;Koltyn 2000). EIH describes an acute reduction in pain and pain sensitivity following exercise. ...
... Yet, EIH is more variable in chronic pain patients where pain sensitivity may remain unchanged or even increase in response to exercise (Vaegter and Jones 2020). The physiological mechanisms underlying EIH are currently incompletely understood, but most likely include the endogenous opioid system (Koltyn 2000) as well as the endocannabinoid (Dietrich and McDaniel 2004) and serotonergic (Lima et al. 2017) system, the autonomic nervous system, and cerebral blood flow (Malfliet et al. 2018). ...
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Purpose Acute physical activity leads to exercise-induced hypoalgesia (EIH). The aim of this study was to investigate the effects of four different exercise intensities on EIH. Methods 25 male (age: 24.7 ± 3.0) subjects underwent four different exercise sessions on a bicycle ergometer for 30 min each at 60, 80, 100, and 110% of the individual anaerobic threshold on separate days in a randomized crossover design. Before, as well as 5- and 45-min post-exercise, pain sensitivity was measured employing pain pressure thresholds (PPT) at the elbow, knee, and ankle joints as well as the sternum and forehead. Besides, conditioned pain modulation (CPM) was conducted using thermal test- and conditioned stimuli before, 5-, and 45-min post-exercise. Results A main time effect was observed regarding PPT at all landmarks except for the forehead with higher values observed 5 and 45 min post-exercise compared to the pre-values. Yet, no interaction effects occurred. CPM did not change in response to any of the intensities used. Conclusion EIH occurs 5 and 45 min after exercise regardless of the intensity used at the joints and sternum which might be explained by local pain-inhibiting pathways and probably to a limited degree by central mechanisms, as no hypoalgesia was observed at the forehead and no changes in CPM occurred.
... Chronic pain is associated with dysfunctional painmodulatory mechanisms de Souza et al., 2009;Heneweer et al., 2009;Olesen et al., 2010;Potvin et al., 2010;Staud et al., 2003;Vaegter et al., 2016). Impairments in pain modulation have been demonstrated using a host of assessments including via conditioned pain modulation (CPM) de Souza et al., 2009;Heneweer et al., 2009;Olesen et al., 2010;Potvin et al., 2010;Staud et al., 2003;Vaegter et al., 2016) and exercise-induced hypoalgesia (EIH) (Crombie et al., 2017;Koltyn, 2000;Koltyn et al., 2014). Despite these consistent findings, the interaction of body composition and sex on pain modulation remains understudied. ...
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Background: Obese individuals report a higher susceptibility to chronic pain. Females are more likely to have chronic pain and excess adipose tissue. Chronic pain is associated with dysfunctional pain modulatory mechanisms. Body composition differences may be associated with pain modulation differences in males and females. The purpose of this study was to investigate body composition (lean vs fat mass) differences and pain modulatory functioning in healthy males and females. Methods: Pressure pain thresholds (PPT) of 96 participants (47M; 49F) were assessed in both arms and legs before and after a double footed ice bath (2°C) for 1min and an isometric knee extension, time to failure task. The difference between post and pre measures was defined conditioned pain modulatory (CPM) response (ice bath) and exercise induced hypoalgesia (EIH) response. Whole body and site-specific fat and lean tissue were assessed via DXA scan. Results: Sex differences were found in whole body lean mass (61.5±6.7kg vs 41.2±5.4kg; P<0.001) but not fat mass amount (17.2±10.5kg vs 21.0±9.7kg; P=0.068). No effect of sex was found between limb CPM (P=0.237) and limb EIH (P=0.512). When controlling for lean mass there was no significant effect of sex on CPM (P=0.732) or EIH (P=0.474) response. Similar findings were found for fat mass. Conclusion: The lack of difference suggests that males and females have similar modulatory functioning. It appears that in healthy adults free from chronic pain, neither fat mass nor lean mass has an influence on endogenous pain modulatory function.
... Pain thresholds increase during and after exercise because of the release of opioids and growth factors from the central nervous system, as well as the pain inhibition mechanism. 28 Different forms of exercise may produce different analgesic effects and have different effects on PPTs. Hoffman et al concluded that an exercise intensity of more than 50% of maximum oxygen uptake and an exercise time of more than 10 minutes achieve the analgesic effect and reduce pressure pain test scores in healthy people. ...
Article
Purpose: Although studies on the improvement of pain after exercise are increasingly diverse, whether Tai Chi Quan can improve the pressure pain thresholds remains unknown. This study was to observe the effect of Tai Chi Quan on the pressure pain thresholds of lower back muscles in healthy women. Patients and methods: This was a randomized controlled trial. Sixty healthy women aged 18-40 years were randomly assigned to Tai Chi group or control group. The Tai Chi group received 40-minute practice, and the control group received 5-minute sham Tai Chi Quan practice and 35-minute rest. The pressure pain thresholds of the longissimus thoracis, iliocostalis lumborum, multifidus muscle, quadratus lumborum, gluteus medius and supraspinous ligament were assessed before and immediately after intervention. Results: The pressure pain thresholds of test points in the Tai Chi group showed substantial improvements after exercise, whereas those in the control group did not improve. Overall, the pressure pain thresholds in the Tai Chi group significantly increased compared with the control group (longissimus thoracis: p = 0.000, iliocostalis lumborum: p = 0.000, multifidus muscle: p = 0.000, quadratus lumborum: p = 0.012, gluteus medius: p = 0.000 and supraspinous ligament: p = 0.000). Conclusion: Forty minutes of Tai Chi Quan exercise remarkably increased the pressure pain thresholds of lower back muscles in healthy women, and thresholds at by an these points increased average of 17.2%.
... From the studies reviewed here, one could find a hypoalgesic effect through pain measurement after 30 minutes of running (Crombie and others 2018), while in a group of patients with fibromyalgia and a control group no such effect was detected (Stensson and Grimby-Ekman 2019). These inhomogeneous findings are also reflected in two reviews on this topic (Dannecker and Koltyn 2014;Koltyn 2000). Various variables seem to impact the detection of hypoalgesia after endurance exercise, namely, the method of pain testing, time-points of detection, instruments used for assessing pain (questionnaire, VAS), participants' health condition, exercise form, exercise intensity, and exercise duration. ...
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The runner’s high is an ephemeral feeling some humans experience during and after endurance exercise. Recent evidence in mice suggests that a runner’s high depends on the release of endocannabinoids (eCBs) during exercise. However, little is known under what circumstances eCBs are released during exercise in humans. This systematic review sampled all data from clinical trials in humans on eCB levels following exercise from the discovery of eCBs until April 20, 2021. PubMed/NCBI, Ovid MEDLINE, and Cochrane library were searched systematically and reviewed following the PRISMA guidelines. From 278 records, 21 met the inclusion criteria. After acute exercise, 14 of 17 studies detected an increase in eCBs. In contrast, after a period of long-term endurance exercise, four articles described a decrease in eCBs. Even though several studies demonstrated an association between eCB levels and features of the runner’s high, reliable proof of the involvement of eCBs in the runner’s high in humans has not yet been achieved due to methodological hurdles. In this review, we suggest how to advance the study of the influence of eCBs on the beneficial effects of exercise and provide recommendations on how endocannabinoid release is most likely to occur under laboratory conditions.
... Exercise-induced hypoalgesia is often defined as a reduction in pain sensitivity following an acute bout of exercise (Koltyn, 2000). Due to its hypoalgesic effect, exercise has been considered as a method for pain management among chronic pain populations such as patients with musculoskeletal pain (Ge et al., 2012;Kosek et al., 2013;Meeus et al., 2010;Rice et al., 2019;Vaegter et al., 2017). ...
Article
The purpose was to examine the effect of isometric handgrip exercise with and without blood flow restriction on exercise-induced hypoalgesia at a local and non-local site, and its underlying mechanisms. Sixty participants (21 males & 39 females, 18–35 years old) completed 3 trials: four sets of 2-minute isometric handgrip exercise at 30% of maximum handgrip strength; isometric handgrip exercise with blood flow restriction at 50% of arterial occlusion pressure; and a non-exercise time-matched control. Pain thresholds increased similarly in both exercise conditions at a local (exercise conditions: ~0.45 kg/cm², control: ~-0.04 kg/cm²) and non-local site (exercise conditions: ~0.37 kg/cm², control: ~-0.16 kg/cm²). Blood flow restriction induced greater feelings of discomfort compared to exercise alone [median difference (95% credible interval) of 4.5 (0.5, 8.6) arbitrary units]. Blood pressure increased immediately after exercise (systolic: 10.3 mmHg, diastolic: 7.7 mmHg) and decreased in recovery. There was no within participant correlation between changes in discomfort and pressure pain threshold. A bout of isometric handgrip exercise with or without blood flow restriction can provide exercise-induced hypoalgesia at a local and non-local site. However, discomfort and changes in systolic blood pressure do not explain this response.
Article
Background Plantar heel pain (PHP), or plantar fasciopathy, is a common condition in active and sedentary populations, contributing to short- and long-term reductions in quality of life. The condition's aetiology and pathophysiology are the subjects of a significant body of research. However, much of this research has been conducted with sedentary participants, and comparatively little research exists in a population of highly-trained athletes focused on performance outcomes. Models for PHP and proposed mechanisms, such as high body mass index or systemic disease, are mostly absent from an athletic population. Even less is known about the origins of pain in PHP. Pain is believed to be a complex multifactorial process and may be experienced differently by sedentary and highly active populations, particularly endurance athletes. Consequently, conservative through to surgical treatment for athletes is informed by literature for a different population, potentially hindering treatment outcomes. Aims The aim of this review, therefore, is to summarise what is known about PHP in athletic populations and propose potential directions for future research. Methods Embase, PubMed, and Scopus using MeSH search terms for PHP and competitive sport and common synonyms. Discussion Two explanatory models for PHP were found. These primarily propose mechanical factors for PHP. It remains unclear how gait, body composition, and psychological factors may differ in an athletic population with and without PHP. Therefore, research in these three area is needed to inform clinical and training interventions for this population.
Article
Subjective pain perception and the ability to modulate arising pain vary greatly between individuals. (Endurance) sport is one possibility to modulate pain perception. One differentiates between a short-term effect during/after a single exercise session (exercise-induced-hypoalgesia [EIH]) and a long-term effect in athletes who regularly engage in exercise. Many studies have shown that the endogenous opioid system and the endogenous cannabinoid system are involved in EIH. Furthermore, it has been demonstrated that endurance athletes generally have higher pain tolerance thresholds in response to physically identical pain stimuli and also show a greater effect of conditioned pain modulation (CPM) than nonathletes, whereby the difference increases with more extensive weekly training among the athletes. Both of the latter effects indicate a more efficient system of endogenous pain inhibition in the endurance athletes. A recently published study focused on the neural mechanisms of pain processing in endurance athletes using functional magnetic resonance imaging. The results of this study demonstrated for the first time that endurance athletes not only reported subjective differences in pain perception, but also exhibited altered neural processing of pain. Longitudinal studies are needed to investigate whether (endurance) sport can be used to prevent chronic pain states.
Chapter
Die „exercise induced hypoalgesia“ (EIH) ist nur wenig aufgeklärt. Physische Belastungen aktivieren die Endocannabinoide. Ihre Wirkungen sind aber nicht die alleinige Ursache, sondern auch die Plastizität der relevanten Gehirnstrukturen. Dem PFC unterliegt die Top-down-Kontrolle sensorischer und affektiver Vorgänge einschließlich der Schmerzen, und das Belohnungssystem ist einbezogen. Mannigfaltige weitere Veränderungen im Nervengewebe finden statt. Der aktive Muskel mit dem Myokin IL-4 ist ein Faktor der peripheren Mechanismen. Die EIH benötigt Ermüdung. Sie kann ein Parameter des Ausprägungsgrades sein. Es fehlen belegte Empfehlungen in Abhängigkeit von der Pathogenese und dem Alter. Die anti-nozizeptive Reorganisation des Gehirns benötigt sehr viel Zeit. Bei Chronifizierung ist die EIH variabel. Eine Schmerzverstärkung kann auftreten, weil die Belastbarkeit der Schmerzhemmung überschritten wird. Das Training der nicht vordergründig betroffenen Körperregionen sollte ein wichtiges Element sein.
Article
Purpose: The cold pain sensitivity in fighter pilots was studied by using a cold pressor test. Methods: The pilots were divided into two groups: one group consisting of eight pilots (N = 8) who had experienced several acute in-flight neck pain attacks, and the control group (N = 8) who had not experienced these pain conditions under similar work and environment conditions. In each pilot cold pain thresholds and pain and unpleasantness responses to suprathreshold cold stimulations were recorded during repeated tests. The ratings of pain and unpleasantness responses to cold stimulations were evaluated by visual analog scales (VAS). The effect of exercise on cold pain sensitivity was tested in a separate experiment. Exercise was performed on a cycle ergometer at different workload levels (50-200 W). Results: In the control conditions (resting measures) of this study during repeated cold pressor tests, the average pain thresholds and pain or unpleasantness responses to suprathreshold cold stimulation were not different between groups. Physical exercise increased pain thresholds (P < 0.001) in pilots with a history of neck pain attacks but not in control group. Exercise induced a significant decrease in pain responses and unpleasantness responses to suprathreshold stimulation in both groups. This exercise effect was more marked both in pain intensity (P < 0.05) and unpleasantness responses (P < 0.01) in pilots with a history of neck pain attacks. Moreover, exercise more markedly (P < 0.05) decreased unpleasantness than pain intensity responses in both groups of pilots. Conclusions: The results suggest that exercise stress-related analgesia mechanisms may be enhanced in pilots with a history of acute in-flight neck pain attacks. Moreover, sensory and nonsensory aspects of pain experience may be differentially influenced by exercise stress.
Article
This study aimed at evaluating the influence of submaximal isometric contraction on pressure pain thresholds (PPTs) in 14 healthy volunteers before and after skin hypoesthesia. PPTs were determined with pressure algometry over m. quadriceps femoris before, during, and following an isometric contraction. Maximum voluntary contraction (MVC) was assessed using a computerized dynamometer. A contraction of 21% MVC was held until exhaustion (max: 5 min) and PPTs were assessed every 30 sec. A local anesthetic cream and a control cream were applied following a double-blind design and PPTs were reassessed. PPTs increased significantly at the start of contraction and continued to increase until the middle of the contraction period, then remaining at this level. After contraction PPTs decreased significantly but for 5 min remained slightly above precontraction levels. Anesthetic cream raised PPT at rest but not during and following contraction. The relative increase in PPTs during and immediately following isometric contraction was lower with anesthetic cream. Isometric contraction of m. quadriceps femoris increase PPTs during and following contraction. The results suggest that input from cutaneous and deeper tissues interacts with nociceptive activity set up by the pressure stimulus. Determining the degree of sensory modulation in muscle and skin in different chronic pain syndromes could become a functional method of patient assessment important for differential diagnosis, treatment evaluation, and follow-up.
Article
Padawer and Levine (lYY2f discuss whether exercise-induced analgesia is a fact or artifact. They suggest that the exercise-induced analgesic rffect may he an artifact of reactivity to pain tests. They found that pain intensity ratings for the cold pressor test were significantly reduced after pre-exposure to the same pain test. However , in the experimental design chosen by these authors, they were unable to detect an exercise effect on pain intensity rating. It is important to note that an experimental pain test itself can activate endoyenous pain modulation. It follows that in order to determine an analgesic effect of any intervention a control group should be introduced into the experimental design. The fact that Padawer and Levine could measure a reduction in pain intensity and unpleasantness ratings in a repetition of the cold pressor test is not unexpected and is moat likely due to the novelty of the first trial. Among the many different experimental pain tests, the cold pressor test is strongly influenced by cognitive coping processes, which is one reason why ii has been often used to study psychoi~~gi~dl intervcn-tions in pain.
Article
Many clinical pain conditions, including migraine, fibromyalgia, and temporomandibular disorders, occur more frequently among females than males. Greater pain sensitivity among females has been considered as one possible explanation for these differences. Despite considerable clinical and experimental research on the topic, no consensus has emerged on the existence or nature of gender differences in response to noxious stimuli. In this Focus article the authors take the position that females exhibit greater sensitivity to noxious stimuli than males. In support of this position, they review the experimental literature on gender and pain responses. Then, they present and discuss a schematic model of several systems involved in the transmission and modulation of nociceptive information, which may contribute to gender-associated differences in pain sensitivity. Finally, the authors highlight several issues to be addressed by future research in this area.
Article
This study aimed at evaluating the influence of submaximal isometric contraction on pressure pain thresholds (PPTs) in 14 fibromyalgia (FM) patients and 14 healthy volunteers, before and after skin hypoesthesia. PPTs were determined with pressure algometry over m. quadriceps femoris before, during and following an isometric contraction. Maximum voluntary contraction (MVC) was assessed using a computerized dynamometer. A contraction of 22% MVC on average was held until exhaustion (max. 5 min) and PPTs were assessed every 30 sec. A local anesthetic cream and a control cream were applied following a double-blind design and PPTs were reassessed. In healthy volunteers,PPTs increased during contraction (P < 0.001), then decreased after the end of contraction (P < 0.001) but remained above precontraction values during the 5 min of post-contraction assessments (P < 0.001). In FM patients PPTs decreased in the middle of the contraction period (P < 0.05) and remained below precontraction levels during the rest of the contraction period (P < 0.05) and during the 5 min of post-contraction assessment (immediately post-contraction NS; 2.5 min post-contraction P < 0.01; 5 min post-contraction P < 0.05). The normalized PPTs were significantly lower in patients than in controls during contraction (start P < 0.01; middle P < 0.001; end P < 0.001.) and at all times during post-contraction assessments (P < 0.001). Anesthetic cream raised PPTs at rest in controls (P < 0.01) but not in FM patients, and did not influence contraction or post-contraction PPTs in either group. Therefore, the increased pressure pain sensibility in FM patients is more pronounced deep to the skin. The observed decrease of PPTs during isometric contraction in FM patients could be due to sensitization of mechanonociceptors caused by muscle ischemia and/or dysfunction in pain modulation during muscle contraction.
Article
In mice, the stress of swimming induces analgesia, as revealed by the hot-plate test. For approximately 5 min after the end of swimming the degree of analgesia remains constant; it decreases thereafter and is undetectable after 25–30 min.The analgesia is apparent after a swim as short as 15 sec and with longer swims (up to 7.5 min) the magnitude of analgesia increases.Analgesia is apparent after swimming in water at body temperature (38°C). Decreasing the water temperature to 21°C increases the analgesia slightly; further decreases greatly increase the magnitude of this analgesia.
Article
Fillingim and Maixner (Fillingim, R.B. and Maixner, W., Pain Forum, 4(4) (1995) 209–221) recently reviewed the body of literature examining possible sex differences in responses to experimentally induced noxious stimulation. Using a `box score' methodology, they concluded the literature supports sex differences in response to noxious stimuli, with females displaying greater sensitivity. However, Berkley (Berkley, K.J., Pain Forum, 4(4) (1995) 225–227) suggested the failure of a number of studies to reach statistical significance suggests the effect may be small and of little practical significance. This study used meta-analytic methodology to provide quantitative evidence to address the question of the magnitude of these sex differences in response to experimentally induced pain. We found the effect size to range from large to moderate, depending on whether threshold or tolerance were measured and which method of stimulus administration was used. The values for pressure pain and electrical stimulation, for both threshold and tolerance measures, were the largest. For studies employing a threshold measure, the effect for thermal pain was smaller and more variable. The failures to reject the null hypothesis in a number of these studies appear to have been a function of lack of power from an insufficient number of subjects. Given the estimated effect size of 0.55 threshold or 0.57 for tolerance, 41 subjects per group are necessary to provide adequate power (0.70) to test for this difference. Of the 34 studies reviewed by Fillingim and Maixner, only seven were conducted with groups of this magnitude. The results of this study compels to caution authors to obtain adequate sample sizes and hope that this meta-analytic review can aid in the determination of sample size for future studies.