Exercise-Induced Hypoalgesia in Healthy Individuals and People With Chronic Musculoskeletal Pain: A Systematic Review and Meta-Analysis

Exercise-induced hypoalgesia (EIH) is a reduction in pain that occurs during or following exercise. Randomized controlled studies published from 1980 to January 2020 that examined experimentally induced pain before and during/following a single bout of exercise in healthy individuals or people with chronic musculoskeletal pain were systematically reviewed. Data were analyzed using random-effects meta-analyses and studies were appraised using the Cochrane Risk of Bias tool and GRADE. Five thousand eight hundred twenty-nine records were screened, with 13 studies ultimately included. In healthy individuals, aerobic exercise caused large EIH (7 studies, 236 participants; g = ?.85 [?1.58, ?.13]), dynamic resistance exercise caused small EIH (2 studies, 23 participants; g = ?.45 [?.69, ?.22]), and isometric exercise did not cause EIH (3 studies, 177 participants; g = ?.16 [?.36,.05]). In chronic musculoskeletal pain, isometric exercise did not cause EIH (3 studies, 114 participants; g = ?.41 [?1.08,.25]); aerobic (0 studies) and dynamic resistance (1 study) exercise were not analyzed. We conclude that, based on small studies with unclear risk of bias, aerobic and dynamic resistance exercise reduce experimental pain in healthy individuals. Further research is needed to determine whether EIH exists for experimental and clinical pain in people with chronic musculoskeletal pain.Registration: PROSPERO ID: CRD42018085886.PerspectiveBased on low-quality data from small samples, a single bout of aerobic exercise reduces experimental pain in healthy individuals. The evidence is unclear in people with chronic musculoskeletal pain but warrants further investigation due to the limited number of studies in these populations.     

Mechanisms of Exercise-Induced Hypoalgesia

The purpose of this study was to examine opioid and endocannabinoid mechanisms of exercise-induced hypoalgesia (EIH). Fifty-eight men and women (mean age = 21 years) completed 3 sessions. During the first session, participants were familiarized with the temporal summation of heat pain and pressure pain protocols. In the exercise sessions, following double-blind administration of either an opioid antagonist (50 mg naltrexone) or placebo, participants rated the intensity of heat pulses and indicated their pressure pain thresholds and pressure pain ratings before and after 3 minutes of submaximal isometric exercise. Blood was drawn before and after exercise. Results indicated that circulating concentrations of 2 endocannabinoids, N-arachidonylethanolamine and 2-arachidonoylglycerol, as well as related lipids oleoylethanolamide, palmitoylethanolamide, N-docosahexaenoylethanolamine, and 2-oleoylglycerol, increased significantly (P < .05) following exercise. Pressure pain thresholds increased significantly (P < .05), whereas pressure pain ratings decreased significantly (P < .05) following exercise. Also, temporal summation ratings were significantly lower (P < .05) following exercise. These changes in pain responses did not differ between the placebo and naltrexone conditions (P > .05). A significant association was found between EIH and docosahexaenoylethanolamine. These results suggest involvement of a nonopioid mechanism in EIH following isometric exercise.PerspectiveCurrently, the mechanisms responsible for EIH are unknown. This study provides support for a potential endocannabinoid mechanism of EIH following isometric exercise.     

VO2max in patients with chronic pain: The effect of a 4-week rehabilitation program

BackgroundIn patients with chronic pain, aerobic deconditioning can explain part of observed disability and disadvantage. The objective of the present study was to assess the change in VO₂max after a four-week exercise rehabilitation programme in this population.MethodsIn a prospective study, 121 patients underwent a cycle ergometer exercise tolerance test with VO₂max measurement before and after a four-week exercise rehabilitation programme (which included aerobic training, muscle strengthening, occupational therapy and stretching).ResultsWe observed a statistically significant increase in VO₂max (P = 0.03) and an improvement in the patients’ distribution according to the Shvartz fitness classification after rehabilitation.DiscussionThe four-week exercise rehabilitation program was associated with an improvement in aerobic capacities in patients with chronic pain. However, in all but one of the 121 patients, the VO₂max value at the end of the program was below average for gender and age. Maintenance of aerobic training after the end of a rehabilitation programme is essential.     

Effect of Type and Dose of Exercise on Neuropathic Pain After Experimental Sciatic Nerve Injury: A Preclinical Systematic Review and Meta-Analysis

This preclinical systematic review aimed to determine the effectiveness of different types and doses of exercise on pain behavior and biomarkers in preclinical models of focal neuropathic pain. We searched MEDLINE, EMBASE, Web of Science, PubMed, SCOPUS, CINAHL, and Cochrane library from inception to November 2022 for preclinical studies evaluating the effect of exercise compared to control interventions on neuropathic pain behavior after experimental sciatic nerve injury. If possible, data were meta-analyzed using random effect models with inverse-variance weighting. Thirty-seven studies were included and 26 meta-analyzed. Risk of bias (SYRCLE tool) remained unclear in most studies and reporting quality (CAMARADES) was variable. Exercise reduced mechanical (standardized mean differences [SMD] .53 (95% CI .31, .74), P = .0001, I² = 0%, n = 364), heat (.32 (.07, .57), P = .01, I² = 0%, n = 266) and cold hypersensitivity (.51 (.03, 1.0), P = .04, I² = 0%, n = 90) compared to control interventions. No relationship was apparent between exercise duration or intensity and antinociception. Exercise modulated biomarkers related to different systems (eg, immune system, neurotrophins). Whereas firm conclusions are prevented by the use of male animals only, variable reporting quality and unclear risk of bias in many studies, our results suggest that aerobic exercise is a promising tool in the management of focal neuropathic pain.PerspectiveThis systematic review and meta-analysis demonstrates that aerobic exercise reduces neuropathic pain-related behavior in preclinical models of sciatic nerve injury. This effect is accompanied by changes in biomarkers associated with inflammation and neurotrophins among others. These results could help to develop exercise interventions for patients with neuropathic pain.     

Efficacy of Videoconference Group Acceptance and Commitment Therapy (ACT) and Behavioral Activation Therapy for Depression (BATD) for Chronic Low Back Pain (CLBP) Plus Comorbid Depressive Symptoms: A Randomized Controlled Trial (IMPACT Study)

This study examined the efficacy of adding a remote, synchronous, group, videoconference-based form of acceptance and commitment therapy (ACT) or behavioral activation therapy for depression (BATD) to treatment-as-usual (TAU) in 234 patients with chronic low back pain (CLBP) plus comorbid depressive symptoms. Participants were randomly assigned to ACT, BATD, or TAU. Compared to TAU, ACT produced a significant reduction in pain interference at posttreatment (d = .64) and at follow-up (d = .73). BATD was only superior to TAU at follow-up (d = .66). A significant reduction in pain catastrophizing was reported by patients assigned to ACT and BATD at posttreatment (d = .45 and d = .59, respectively) and at follow-up (d = .59, in both) compared to TAU. Stress was significantly reduced at posttreatment by ACT in comparison to TAU (d = .69). No significant between-group differences were found in depressive or anxiety symptoms. Clinically relevant number needed to treat (NNT) values for reduction in pain interference were obtained at posttreatment (ACT vs TAU = 4) and at follow-up (ACT vs TAU = 3; BATD vs TAU = 5). In both active therapies, improvements in pain interference at follow-up were significantly related to improvements at posttreatment in psychological flexibility. These findings suggest that new forms of cognitive-behavioral therapy are clinically useful in improving pain interference and pain catastrophizing. Further research on evidence-based change processes is required to understand the therapeutic needs of patients with chronic pain and comorbid conditions.Trial numberNCT04140838.PerspectiveGroup videoconference-based ACT and BATD showed greater efficacy than TAU for reducing pain interference and pain catastrophizing in patients with CLBP plus clinically relevant depression. Psychological flexibility appeared to be the main contributor to treatment effects for both ACT and BATD.     

The addition of thoracic mobilization to aerobic exercise did not alter autonomic function and pain pressure threshold acutely in asymptomatic young people: A randomized controlled trial

ObjectiveTo analyze the influence of acute aerobic exercise (AE) plus thoracic mobilization in pain perception and autonomic nervous system response in healthy adults.DesignRandomized clinical trial.MethodsForty-eight asymptomatic adults were allocated into one of three groups: 1) Aerobic Exercise (AE), 2) Aerobic Exercise + Mobilization (AE + M), and 3) Placebo. Participants from groups AE and AE + M ran for 5 min on a treadmill with a 75–85% of age-predicted heart rate. Participants from AE + M group also received a rotatory thoracic passive accessory intervertebral mobilization at T4 after running. Participants from the Placebo group received placebo mobilization. We mesured the autonomic system modulation through Heart Rate Variability (HRV) (time-domain, frequency-domain, and non-linear variables). We measured Pressure Pain Threshold (PPT) with a handheld digital algometer.ResultsWhile aerobic exercise increased the sympathetic outflow and reduced the HRV, the addition of vertebral mobilization to exercise had no further effect on autonomic system modulation. There was no change in PPT in any group. Besides, there was no correlation between HRV and PPT.ConclusionThoracic mobilization did not increase the sympathetic response induced by aerobic exercise. Moreover, exercise alone or exercise plus thoracic mobilization did not change the PPT.     

Immediate Effects of Single-Session Proprioceptive Neuromuscular Facilitation Exercises on the Sit-to-Stand Strategy in Patients With Chronic Lumbar Spinal Disc Disease: A Preliminary Study

ObjectiveThe purpose of this study was to measure the immediate effects of single-session proprioceptive neuromuscular facilitation exercises on the sit-to-stand (STS) task and level of pain in patients with chronic low back pain.MethodsFifty-three patients were assigned to the control and intervention groups. The total time was 30 minutes (each exercise 5 minutes). The minimum vertical ground reaction force (VGRF_min) and maximum vertical ground reaction force (VGRF_max) and time phases (T_min – time to counterforce, T_max – time to peak force, T_tot – time to post-peak rebound force) were measured with a Kistler force plate in eyes-open and eyes-closed conditions during the STS task. Pain level was determined on a numeric rating scale.ResultsMain effects were observed only in the intervention group: decreasing pain value (F = 25.398, P < .0001), increasing T_min (F = 5.72, P = .0044), decreasing T_max (F = 3.43, P = .04), and decreasing T_tot (F = 3.935, P = .02258). There was a main effect of the eyes factor on VGRF_min (F = 12.53, P < .0001) and VGRF_max (F = 7.16, P < .01).ConclusionImmediate effects of single-session proprioceptive neuromuscular facilitation exercises were observed in decreasing the level of pain. Adaptation effects were noted in the retention test. The STS task could be optimized in time phases and dynamic movements in patients with chronic low back pain.     

The Pain Course: A randomised controlled trial of a clinician-guided Internet-delivered cognitive behaviour therapy program for managing chronic pain and emotional well-being

The present study evaluated the efficacy of a clinician-guided Internet-delivered cognitive behaviour therapy (iCBT) program, the Pain Course, to reduce disability, anxiety, and depression associated with chronic pain. Sixty-three adults with chronic pain were randomised to either a Treatment Group or waitlist Control Group. Treatment consisted of 5 iCBT-based lessons, homework tasks, additional resources, weekly e-mail or telephone contact from a Clinical Psychologist, and automated e-mails. Twenty-nine of 31 Treatment Group participants completed the 5 lessons during the 8-week program, and posttreatment and 3-month follow-up data were collected from 30/31 and 29/31 participants, respectively. Treatment Group participants obtained significantly greater improvements than Control Group participants in levels of disability, anxiety, depression, and average pain levels at posttreatment. These improvements corresponded to small to large between-groups effect sizes (Cohen’s d) at posttreatment for disability (d = .88), anxiety (d = .38), depression (d = .66), and average pain (d = .64), respectively. These outcomes were sustained at follow-up and participants rated the program as highly acceptable. Overall, the clinician spent a total mean time of 81.54 minutes (SD 30.91 minutes) contacting participants during the program. The results appear better than those reported in iCBT studies to date and provide support for the potential of clinician-guided iCBT in the treatment of disability, anxiety, and depression for people with chronic pain.     

Pulmonary Functions in Patients With Chronic Neck Pain: A Case-Control Study

ObjectiveThe purpose of the study was to investigate pulmonary functions of patients with chronic neck pain and compare them with those of asymptomatic controls.MethodsThis case-control study was conducted with 25 patients with chronic neck pain (age, 26.84 ± 7.89 years) and 27 age-matched asymptomatic controls (age, 25.96 ± 7.13 years). Pulmonary function tests were performed using spirometry (Quark PFT, COSMED, Rome, Italy). Forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), forced expiratory flow at 25% to 75% vital capacity, peak expiratory flow, maximum voluntary ventilation, and the FEV₁/FVC ratio were measured and are expressed as (%) predicted value for patients with chronic neck pain and asymptomatic controls.ResultsThe chronic neck pain group had lower FEV₁ (P = .015), FVC (P = .029), forced expiratory flow at 25% to 75% vital capacity (P = .040), and maximum voluntary ventilation (P = .042) compared with asymptomatic controls; however, FEV₁/FVC (P = .470) and peak expiratory flow (P = .183) were similar in both groups.ConclusionThese results demonstrated that dynamic lung volumes were lower in patients with chronic neck pain compared with asymptomatic controls.     

Should Exercises be Painful or not? Effects on Clinical and Experimental Pain in Individuals with Shoulder Pain

Exercise can reduce pain, however the effect of painful versus non-painful exercises is uncertain. The primary aim of this randomized crossover study was to compare the effect of painful versus nonpainful isometric shoulder exercises on pain intensity after exercise in individuals with rotator cuff-related shoulder pain. Secondary exploratory aims were to describe the effects on pressure pain thresholds (PPTs), conditioned pain modulation (CPM) and muscle strength. On separate days, 35 individuals performed painful isometric shoulder exercises (external rotation; 20% above pain threshold), nonpainful isometric shoulder exercises (external rotation; 20% below pain threshold), and a rest condition, in randomised order. Shoulder pain intensity, PPTs, CPM, and external rotation strength were assessed before, immediately after and 45 minutes after conditions. No significant differences were observed between painful and nonpainful exercises. Visual analogue scale scores increased immediately after both painful and non-painful exercises compared with rest (P = .047, partial ƞ² = .07), but were similar to preexercise levels after 45 minutes. No changes in PPTs, CPM, or muscle strength after exercises compared with rest were observed. Painful and non-painful isometric exercises caused a moderate but short-lasting increase in shoulder pain in individuals with RCRSP. Isometric exercises had no effect on pain sensitivity and shoulder muscle strength or CPM.PerspectiveThis study evaluated for the first time in individuals with rotator cuff-related shoulder pain the effects of painful versus non-painful isometric exercises on different pain-related outcome measures. Both painful and non-painful isometric exercises caused a moderate but relatively short-lasting increase in shoulder pain in individuals with rotator cuff-related shoulder pain.Trial registration number: (ClinicalTrials.gov) NCT03675399     

Effectiveness of a Multimodal Treatment Program for Somatoform Pain Disorder

Chronic pain conditions are highly prevalent, with somatoform pain disorder accounting for a large proportion. However, the psychological forms of treatment currently used achieve only small to medium effect sizes. This retrospective study investigated the effectiveness of a 5‐week multimodal pain program for patients with somatoform pain disorder. The diagnosis of somatoform pain disorder was confirmed by a specialist for anesthesiology and pain management and a specialist for psychosomatic medicine. Therapy outcome was evaluated with a Numeric Rating Scale (NRS), the Pain Disability Index (PDI), and the Pain Perception Scale. Within the study sample (n = 100), all parameters showed a significant and clinically relevant improvement at the end of therapy (P values < 0.001). The highest effect sizes (d) were found for reduction in average pain rating (NRS: d = 1.00) and the affective items of the Pain Perception Scale (SES‐A: d = 0.07). The lowest effect sizes were found for improvement of pain‐related disabilities (PDI: d = 0.42) and sensory items of the Pain Perception Scale (SES‐S: d = 0.50). Despite high chronification of pain condition, with average pain duration of greater than 8 years, the multimodal treatment program showed medium to large effect sizes on the outcome of patients with somatoform pain disorder. Compared with previous data with small to moderate effect sizes, a multimodal program seems to be more effective than other interventions to address somatoform pain disorder.     

Cardiopulmonary exercise testing for evaluation of a randomized exercise training intervention following aortic valve replacement

Aortic valve surgery is the definitive treatment for aortic stenosis (AS). No specific recommendation is available on how exercise training should be conducted and evaluated after aortic valve replacement (AVR). This study aimed to examine the effect of aerobic exercise training on exercise capacity following AVR. In addition to our primary outcome variable, peak oxygen uptake (peakVO₂), the effect on submaximal cardiopulmonary variables including oxygen uptake kinetics (tau), oxygen uptake efficiency slope (OUES) and ventilatory efficiency (VE/VCO₂ slope) was evaluated. Following AVR due to AS, 12 patients were randomized to either a group receiving 12 weeks of supervised aerobic exercise training (EX) or a control group (CON). Exercise capacity was assessed by a maximal cardiopulmonary exercise test (CPET). There was a significant increase in peak load (+28%, P = 0·031) and in peakVO₂ (+23%, P = 0·031) in EX, corresponding to an increase in achieved percentage of predicted peakVO₂ from 88 to 104% (P = 0·031). For submaximal variables, there were only non‐statistically significant trends in improvement between CPETs in EX. In CON, there were no significant differences in any maximal or submaximal variable between CPETs. We conclude that 12 weeks of supervised aerobic exercise training induces significant adaptations in cardiopulmonary function following AVR, especially in regard to maximal variables including peakVO₂. In addition, we provide novel data on the effect on several submaximal variables following exercise training in this group of patients.     

The Effects of Psychological Interventions on Diabetic Peripheral Neuropathy: A Systematic Review and Meta-Analysis

BackgroundPsychological interventions are effective at ameliorating the experience of pain in conditions such as rheumatoid arthritis and chronic back pain. However, their effect on diabetic peripheral neuropathy (DPN) pain has yet to be establishedAimTo assess the effectiveness of psychological interventions on pain and related outcomes in adults with DPN.DesignSystematic review.SettingsCommunity, hospital in-patient and out-patient.Participants/SubjectsAdults with diabetic peripheral neuropathy.MethodsMedline, Embase, PsychInfo, and CINAHL databases together with grey literature and trial registers were searched. A meta-analysis and narrative synthesis of included studies were undertaken.ResultsNine studies were selected from 1610 citations. At short-term follow-up psychological therapies showed a large effect on pain severity (SMD = –0.94, 95%CI [–1.50, –0.37], p = .001), a small effect on pain interference (SMD = –0.39, 95%CI [–0.73, –0.05], p = .02), and a moderate effect on depressive symptoms (SMD = –0.58, 95%CI [–0.95, –0.21], p = .002). Quality of life significantly improved in experimental subjects, (MD = –2.35, 95%CI [–3.99, –0.71], p = .005).At medium-term follow-up there was a large effect on pain severity (SMD = –1.26, 95%CI [–1.76, –0.77], p < .00001) and on pain interference (SMD = –0.91, 95%CI [–1.61, –0.21], p = .01) and a moderate effect on depressive symptoms (SMD = –0.76, 95%CI [–1.48, –0.05], p = .04).At long-term follow-up, improvements in pain interference, mood, and self-care behaviors were reported.ConclusionsThese findings demonstrate that the relationship between pain and perceived control identified in other groups who experience chronic pain may also be replicated in the DPN population. This is an important outcome that can guide further research and associated service developments.     

Differing Characteristics of Human-Shaped Visual Stimuli Affect Clinicians’ Dosage of a Spinal Manipulative Thrust on a Low-Fidelity Model: A Cross-Sectional Study

ObjectiveThe purpose of this study was to determine whether chiropractic clinicians modulate spinal manipulation (SM) thrust characteristics based on visual perception of simulated human silhouette attributes.MethodsWe performed a cross-sectional within-participant design with 8 experienced chiropractors. During each trial, participants observed a human-shaped life-sized silhouette of a mock patient and delivered an SM thrust on a low-fidelity thoracic spine model based on their visual perception. Silhouettes varied on the following 3 factors: apparent sex (male or female silhouette), height (short, average, tall), and body mass index (BMI) (underweight, healthy, obese). Each combination was presented 6 times for a total of 108 trials in random order. Outcome measures included peak thrust force, thrust duration, peak preload force, peak acceleration, time to peak acceleration, and rate of force application. A 3-way repeated measures analysis of variance model was used to for each variable, followed by Tukey's honestly significant difference on significant interactions.ResultsPeak thrust force was reduced when apparent sex of the presented silhouette was female (F_1,7 = 5.70, P = .048). Thrust duration was largely invariant, except that a BMI by height interaction revealed a longer duration occurred for healthy tall participants than healthy short participants (F_4,28 = 4.34, P = .007). Compared to an image depicting obese BMI, an image appearing underweight lead to reduced peak acceleration (F_2,5 = 6.756, P = .009). Clinician time to peak acceleration was reduced in short compared to tall silhouettes (t₇ = 2.20, P = .032).ConclusionVisual perception of simulated human silhouette attributes, including apparent sex, height, and BMI, influenced SM dose characteristics through both kinetic and kinematic measures. The results suggest that visual information from mock patients affects the decision-making of chiropractic clinicians delivering SM thrusts.     

Effects of core stabilization exercises on thickness and activity of trunk and hip muscles in subjects with nonspecific chronic low back pain

BackgroundChanges in trunk and hip muscles are believed to be important in subjects with nonspecific chronic low back pain (NSCLBP), but little is known about specific changes, or how they might be affected by core stabilization exercises. The aim of this study was to compare six key muscles before and after these exercises.MethodsThirty two NSCLBP patients were assigned randomly into two groups: exercise (n = 17) and control (n = 15). On 5 days per week for 4 weeks, the Exercise group performed 16 core stabilization exercises and the Control group received transcutaneous electrical nerve stimulation and a ‘hot-pack’. Surface electromyography (EMG) was used to assess maximum bilateral activity of transversus abdominis (TrA), multifidus (MF) and gluteus maximus (Gmax) muscles. Ultrasound imaging was used to measure the rest and contracted thickness of these muscles. Pain and disability were assessed using a visual analogue scale (VAS) and the Oswestry Disability Index.ResultsWhen left and right-side muscle data were combined, two-way ANOVAs showed a nonsignificant interaction effect for all dependent variables (P > 0.05), significant time effects on resting muscle thickness for TrA (P = 0.01), MF (P = 0.041) and Gmax (P = 0.003), EMG signals of TrA (P = 0.038), pain and disability (P = 0.000). There were a significant group effect on contracted thickness for TrA (P = 0.032) and Gmax (P = 0.026) and disability (P = 0.017).ConclusionsCore stabilization exercises increased contracted thickness of TrA and Gmax muscles and decreased disability in subjects with NSCLBP.     

Effectiveness of electromyographic biofeedback training on quadriceps muscle strength in osteoarthritis of knee

The objective of this randomised controlled trial was to evaluate the effectiveness of electromyographic biofeedback as an add-on therapy with isometric exercise on quadriceps strengthening in patients with osteoarthritis of knee. Thirty three, 10 men and 23 women, patients with osteoarthritis of knee participated in the study. Patients were randomly placed into two groups: a biofeedback group (n = 17) and a control group (n = 16). The biofeedback group received electromyographic biofeedback-guided isometric exercise programme for 5 days a week for 5 weeks, whereas the control group received an exercise programme only. On between-group comparisons, the maximum isometric quadriceps strength in biofeedback group, at the end of 5^th week was significantly greater than that of the control group (p < 0.004). The addition of electromyographic biofeedback to a 5-week isometric exercise program appeared to increase quadriceps muscle strength, compared to the exercise program alone for people with knee osteoarthritis. The finding, however, should be interpreted with caution due to limitations of the study design.     

Influence of Experimental Pain on the Perception of Action Capabilities and Performance of a Maximal Single-Leg Hop

Changes in an individual's state—for example, anxiety/chronic pain—can modify the perception of action capabilities and physical task requirements. In parallel, considerable literature supports altered motor performance during both acute and chronic pain. This study aimed to determine the effect of experimental pain on perception of action capabilities and performance of a dynamic motor task. Performance estimates and actual performance of maximal single-leg hops were recorded for both legs in 13 healthy participants before, during, and after an episode of acute pain induced by a single bolus injection of hypertonic saline into vastus lateralis of 1 leg, with the side counterbalanced among participants. Both estimation of performance and actual performance were smaller (P < .01) during pain than before and after pain. This decrease in estimation and performance during pain was apparent for hops using either leg, but it was greater (P < .01) for the painful leg (−10.8 ± 12.1 cm) than for the control leg (−5.5 ± 7.9 cm). Participants accurately estimated their performance in all conditions for both legs. The results provide evidence that healthy participants have the ability to update the action-scaled relationship between perception and ability during acute pain.PerspectiveThis study demonstrates that the relationship between perceived physical ability and actual performance is effectively updated during acute muscle pain. This match between perceived ability and performance could be relevant during clinical pain assessment, with the potential to be a biomarker of transition from acute to chronic pain state.     

Attentional bias to pain-related information: A meta-analysis

This meta-analysis investigated whether attentional bias, that is, the preferential allocation of attention to information that is related to pain, is a ubiquitous phenomenon. We also investigated whether attentional bias effects are related to the methodological quality of the study, to procedural differences in their measurement, or to individual differences in pain severity, pain-related fear, anxiety, and depression. Results indicated that individuals who experience chronic pain (n = 1023) display an attentional bias towards pain-related words or pictures, but this bias was of a small effect size (d = 0.134), and did not differ from that in control groups (d = 0.082; n = 1398). No evidence was found for an attentional bias towards pain-related words and pictures for acute pain (d = 0.049), procedural pain (d = 0.142), and experimental pain (d = 0.069). However, research in which attentional bias towards signals of impending experimental pain in healthy volunteers was investigated, revealed an attentional bias of medium effect size (d = 0.676). Moderator analyses in the chronic pain group identified important procedural variables that affected the presence and magnitude of an attentional bias towards pain-related words and pictures, that is, type and exposure time of pain-related information. None of the individual difference variables affected the magnitude of the attentional bias. Implications of current findings and future directions are discussed.     

Isometric Exercise Training for Blood Pressure Management: A Systematic Review and Meta-analysis

ObjectiveTo conduct a systematic review and meta-analysis quantifying the effects of isometric resistance training on the change in systolic blood pressure(SBP), diastolic blood pressure (DBP), and mean arterial pressure in subclinical populations and to examine whether the magnitude of change in SBP and DBP was different with respect to blood pressure classification.Patients and MethodsWe conducted a systematic review and meta-analysis of randomized controlled trials lasting 4 or more weeks that investigated the effects of isometric exercise on blood pressure in healthy adults (aged ≥18 years) and were published in a peer-reviewed journal. PubMed, CINAHL, and the Cochrane Central Register of Controlled Trials were searched for trials reported between January 1, 1966, and July 31, 2013. We included 9 randomized trials, 6 of which studied normotensive participants and 3 that studied hypertensive patients, that included a total of 223 participants (127 who underwent exercise training and 96 controls).ResultsThe following reductions were observed after isometric exercise training: SBP—mean difference (MD), −6.77 mm Hg (95% CI, −7.93 to −5.62 mm Hg; P<.001); DBP—MD, −3.96 mm Hg (95% CI, −4.80 to −3.12 mm Hg; P<.001); and mean arterial pressure—MD, −3.94 mm Hg (95% CI, −4.73 to −3.16 mm Hg; P<.001). A slight reduction in resting heart rate was also observed (MD, −0.79 beats/min; 95% CI, −1.23 to −0.36 beats/min; P=.003).ConclusionIsometric resistance training lowers SBP, DBP, and mean arterial pressure. The magnitude of effect is larger than that previously reported in dynamic aerobic or resistance training. Our data suggest that this form of training has the potential to produce significant and clinically meaningful blood pressure reductions and could serve as an adjunctive exercise modality.