Pain Relief after Isometric Exercise Is Not Task-Dependent in Older Men and Women

Effectiveness of proprioceptive neuromuscular facilitation therapy and strength training among post-menopausal women with thumb carpometacarpal osteoarthritis. A randomized trial

BACKGROUND

Thumb carpometacarpal osteoarthritis (CMC OA) greatly affects post-menopausal women. It is characterized by pain and functional deficits that limit the performance of activities of daily life and affect quality of life.

PURPOSE

Analyze the effects of 4/weeks strength training, with and without proprioceptive neuromuscular facilitation (PNF) on the disability among post-menopausal women with thumb CMC OA. Secondly, analyze the effects on pain, mobility, and strength.

STUDY DESIGN

Superiority randomized clinical trial.

METHODS

42 women were randomly allocated to strength training program (SEG, n = 21) and to a strength training plus PNF therapy program (PNFG, n = 21). The Disability (disabilities of the arm, shoulder and hand questionnaire), pain (visual analogue scale), mobility (Kapandji Test), and hand strength were evaluated pre, post intervention (at 4 weeks) and follow-up (at 8 weeks).

RESULTS

Disability was significantly reduced in both groups after intervention, but reduction was statistically superior in PNFG (between-group mean difference [MD] = -16.69 points; CI = -21.56:-11.82; P<.001; d = 2.14). Similar results were observed for secondary outcomes: pain (MD = -2.03; CI = -2.83:-1.22; P<.001; d = 1.58), mobility (MD = 0.96; CI = 0.52:1.38; P<.001; d = 1.40) and strength (grip: MD = 3.47kg; CI = 1.25:5.69; P = .003; d = 0.97, palmar: MD = 0.97kg; CI = 0.14:1.80; P = .024; d = 0.72, tip: MD = 1.12kg; CI = 0.41:1.83; P = .003; d = 0.99 and key pinch: MD = 0.85kg; CI = 0.001:1.70; P = .049; d = 0.62). These improvements were maintained at follow-up.

CONCLUSIONS

The combination of PNF exercises and strength training is more effective for reducing disability pain and improve mobility and strength in post-menopausal women with CMC OA than a programme based solely on strength.

Isometric versus isotonic exercise in individuals with rotator cuff tendinopathy-Effects on shoulder pain, functioning, muscle strength, and electromyographic activity: A protocol for randomized clinical trial

INTRODUCTION

Rotator cuff tendinopathy is a common shoulder disorder in which the primary treatment is resistance exercises. Isometric exercises are being studied for lower limb tendinopathies but not for rotator cuff tendinopathy. This protocol for a randomized clinical trial aims to compare the effects of two types of exercise (isometric and isotonic) on shoulder pain, functioning, muscle strength, and electromyographic activity in individuals with rotator cuff tendinopathy.

METHODS

Forty-six individuals (18 to 60 years old) with shoulder pain for more than three months and unilateral supraspinatus and/or infraspinatus tendinopathy will participate in this trial. Individuals will be randomized into two exercise groups: isometric or isotonic. The following outcomes will be evaluated before and after the first session and after six weeks of intervention: shoulder pain and functioning; isometric strength of shoulder elevation and lateral and medial rotation; and electromyographic activity of medial deltoid, infraspinatus, serratus anterior, and lower trapezius. Groups will perform stretching and strengthening of periscapular muscles. The isometric group will perform three sets of 32 s, at 70% of maximal isometric strength. The isotonic group will perform concentric and eccentric exercises (2 s for each phase) in three sets of eight repetitions at a load of eight repetition maximum. The total time under tension of 96 s will be equal for both groups, and load will be adjusted in weeks three and five of the protocol. Treatment effect between groups will be analyzed using linear mixed model.

TRIAL REGISTRATION

Trial registration number: Universal Trial Number (UTN) code U1111-1284-7528 and Brazilian Clinical Trials Registry platform-RBR-3pvdvfk.

Upper-Limb Kinematic Behavior and Performance Fatigability of Elderly Participants Performing an Isometric Task: A Quasi-Experimental Study

Upper-limb position-sustained tasks (ULPSIT) are involved in several activities of daily living and are associated with high metabolic and ventilatory demand and fatigue. In older people, this can be critical to the performance of daily living activities, even in the absence of a disability.

OBJECTIVES

To understand the ULPSIT effects on upper-limb (UL) kinetics and performance fatigability in the elderly.

METHODS

Thirty-one (31) elderly participants (72.61 ± 5.23 years) performed an ULPSIT. The UL average acceleration (AA) and performance fatigability were measured using an inertial measurement unit (IMU) and time-to-task failure (TTF).

RESULTS

The findings showed significant changes in AA in the X- and Z-axes (p < 0.05). AA differences in women started earlier in the baseline cutoff in the X-axis, and in men, started earlier between cutoffs in the Z-axis. TTF was positively related to AA in men until 60% TTF.

CONCLUSIONS

ULPSIT produced changes in AA behavior, indicative of movement of the UL in the sagittal plane. AA behavior is sex related and suggests higher performance fatigability in women. Performance fatigability was positively related to AA only in men, where movement adjustments occurred in an early phase, though with increased activity time.

The Interaction Between Psychosocial Factors and Exercise-Induced Hypoalgesia in Pain-Free Nurses

Purpose

This cross-sectional study aimed to investigate whether psychosocial factors were predictive for exercise-induced hypoalgesia (EIH) in pain-free adults.

Methods

A sample of 38 pain-free nurses with a mean (SD) age of 26 (6) years were included in this study. Participants completed psychosocial questionnaires prior to physical tests. Pressure pain threshold (PPT) was assessed bilaterally at the calves (local), lower back (semi-local) and forearm (remote) before and immediately after a maximal graded cycling exercise test. Separate linear mixed effects models were used to determine change in PPT before and after cycling exercise (EIH). Multiple linear regression for all psychosocial variables and best subset regression was used to identify predictors of EIH at all locations.

Results

The relative mean increase in PPT at the forearm, lumbar, calf, and globally (all sites pooled) was 6.0% (p<0.001), 10.1% (p<0.001), 13.9% (p<0.001), and 10.2% (p=0.013), respectively. Separate best subset multiple linear regression models at the forearm (predictors; Multidimensional Scale of Perceived Social Support (MSPSS) total), lumbar (predictors; MSPSS total, Pain Catastrophizing Scale (PCS) total, Depression Anxiety Stress Scale (DASS) depression), calf (predictors; MSPSS friends, PCS total), and global (predictors; MSPSS friends, PCS total) accounted for 7.5% (p=0.053), 13% (p=0.052), 24% (p=0.003), and 17% (p=0.015) of the variance, respectively.

Conclusion

These findings confirm that cycling exercise produced EIH in young nurses and provided preliminary evidence to support the interaction between perceived social support, pain catastrophizing and EIH. Further investigation is required to better understand psychological and social factors that mediate EIH on a larger sample of adults at high risk of developing chronic musculoskeletal pain.

Influence of an Upper Limb Isometric Task in Perceived and Performance Fatigability of Elderly Subjects: A Quasi-Experimental Study

Isometric activity can be used as a strategy to improve health, fitness, and functional performance in the elderly population, but differences in fatigability may occur. This study aimed to understand fatigability behavior during an upper limb isometric task (ULIT) and the role of health status and physical activity in the fatigability of elderly participants. Thirty-two (32) elderly participants (72.5 ± 5.18 years) were instructed to perform ULIT. The Borg CR10 scale and task failure point (TTF) were used to measure perceived and performance fatigability. Self-reported measures were used to assess the quality of life and physical activity level. A significant relationship between perceived and performance fatigability was found only in the final phase of activity (p < 0.01). Significant correlations were found between perceived fatigability and the social functioning dimension (p < 0.05), and between performance fatigability (TTF) and BMI (p < 0.01), physical functioning (p < 0.01), and role functioning/physical (p < 0.05) dimensions. In conclusion, ULIT produces changes in fatigability of elderly people, which are positively related in the final stage of the activity. Changes in fatigability are negatively related to BMI. It is also negatively related to health, social functioning, physical functioning and role functioning/physical quality of life dimensions.

Impaired conditioned pain modulation was restored after a single exercise session in individuals with and without fibromyalgia

Supplemental Digital Content is Available in the Text.

Submaximal isometric exercise improved impaired conditioned pain modulation acutely in individuals with and without fibromyalgia, regardless of health status.

Introduction:

Exercise is an effective nonpharmacological intervention for individuals with fibromyalgia syndrome (FMS); however, considerable variability is observed in their pain response after a single exercise session that could be due to differences in baseline central pain inhibition (ie, conditioned pain modulation [CPM]).

Objectives:

This study examined the effect of isometric exercise on CPM in people with FMS and control participants. A subaim was to identify whether pain inhibition after exercise was due to differences in baseline CPM.

Methods:

Twenty-one individuals with FMS (50.5 ± 14.9 years) and 22 age-matched and sex-matched controls (49.2 ± 13.3 years) participated in a familiarization session and 2 randomized experimental sessions: (1) low-intensity isometric exercise and (2) quiet rest control. Conditioned pain modulation was measured before and after each experimental session. In addition, body composition and physical activity levels were collected to determine potential group differences.

Results:

Both groups had comparable body composition and physical activity levels and reported similar exercise-induced hypoalgesia (increase in pressure pain thresholds) at the exercising muscle (quadriceps muscle) and systemically (deltoid muscle). Both groups had a decrease in CPM after exercise and quiet rest; however, in both FMS and control participants with impaired baseline CPM, there was an increase in CPM at the deltoid muscle after exercise.

Conclusion:

In persons with low CPM, irrespective of health status, isometric exercise enhanced CPM at a site distal from the exercising muscle. Our results support the use of isometric exercise when initiating an exercise program especially for individuals with impaired CPM.

Opioid and non-opioid pain relief after an emergency department acute pain visit

OBJECTIVES

Treatment of acute pain after emergency department (ED) discharge remains a challenge in the opioid crisis context. Our objective was to determine the proportion of patients using opioid vs non-opioid pain medication following discharge from the ED with acute pain, and the association of type of pain medication with average pain intensity before pain medication intake and report of pain relief.

METHODS

This was a prospective cohort study of ED patients aged ≥ 18 years with an acute pain (≤ 2 weeks) who were discharged with an opioid prescription. Patients completed a 14-day diary assessing daily pain intensity level before each pain medication intake (0-10 numeric rating scale), type of pain medication use (opioid vs non-opioid), and if pain was relieved by the medication used that day. Multilevel analyses were used to compare the effect of type of analgesic used on pain intensity and relief.

RESULTS

A total of 381 participants completed the 14-day diary; 50% were women and median age was 54 years (IQR = 43-66). Average daily pain intensity before pain medication intake was significantly higher for patients who used opioids (5.9; 95% CI 5.7-6.2) as compared to non-opioid analgesics (4.2; 95% CI 4.0-4.5) or no pain medication (2.2; 95% CI 1.9-2.5). Controlling for pain intensity, patients using opioids were more likely to report a pain relief (OR = 1.3; 95% CI 1.1-1.8) as compared to those who used non-opioid analgesics.

CONCLUSION

Overall, opioids appear to be effective and used as intended by the prescribing physician.

Similar effects of fatigue induced by a repetitive pointing task on local and remote light touch and pain perception in men and women

Background

Women involved in repetitive, fatiguing, jobs develop more neck and/or shoulder musculoskeletal disorders than men. Sex differences in the pain response to exercise could contribute to the higher prevalence of neck/shoulder musculoskeletal disorders in women. The objective of this study was to assess sex differences in pain sensitivity following a fatiguing upper limb task. Relationships between measures of fatigue and of the sensitivity to nociceptive and to non-nociceptive stimulations were also explored.

Methods

Thirty healthy adults (15 women) performed a fatiguing repetitive pointing task with their dominant arm. Upper limb electromyography was recorded from the dominant upper trapezius, anterior deltoid and bicep brachii and from the contralateral tibialis anterior. Before and immediately after the repetitive pointing task, pressure pain and light touch sensitivity thresholds were measured over the same muscles.

Results

Electromyographic signs of fatigue were observed only in the anterior deltoid and biceps brachii muscles. Pressure pain thresholds over both muscles increased slightly (effect size ≤ 0.34), but no changes occurred over the upper trapezius and the tibialis anterior. Light touch thresholds increased moderately to importantly after the repetitive pointing task over all four muscles (effect sizes = 0.58 to 0.87). No sex differences were observed in any sensory variable. Moreover, no or weak correlations (r = -0.27 to 0.39) were observed between electromyographical signs of fatigue, light touch threshold and pressure pain threshold variables.

Conclusions

We observed sex-independent effects of a repetitive upper limb task on the sensitivity to painful and to nonpainful stimuli. Moreover, the hypoalgesia induced by the repetitive pointing task was weak and localized, and did not directly correlate with the induced muscle fatigue. Results suggest that fatigue-related changes in the sensitivity to noxious and innocuous stimuli could not explain women’s greater prevalence of neck/shoulder musculoskeletal disorders.

Exercise-induced hypoalgesia after acute and regular exercise: experimental and clinical manifestations and possible mechanisms in individuals with and without pain

This review describes methodology used in the assessment of the manifestations of exercise-induced hypoalgesia in humans and previous findings in individuals with and without pain. Possible mechanisms and future directions are discussed.

Exercise and physical activity is recommended treatment for a wide range of chronic pain conditions. In addition to several well-documented effects on physical and mental health, 8 to 12 weeks of exercise therapy can induce clinically relevant reductions in pain. However, exercise can also induce hypoalgesia after as little as 1 session, which is commonly referred to as exercise-induced hypoalgesia (EIH). In this review, we give a brief introduction to the methodology used in the assessment of EIH in humans followed by an overview of the findings from previous experimental studies investigating the pain response after acute and regular exercise in pain-free individuals and in individuals with different chronic pain conditions. Finally, we discuss potential mechanisms underlying the change in pain after exercise in pain-free individuals and in individuals with different chronic pain conditions, and how this may have implications for clinical exercise prescription as well as for future studies on EIH.

Exercise-induced pain threshold modulation in healthy subjects: a systematic review and meta-analysis

Background

The use of exercise is a potential treatment option to modulate pain (exercise-induced hypoalgesia). The pain threshold (PT) response is a measure of pain sensitivity that may be a useful marker to assess the effect of physical exercise on pain modulation.

Aim

The aim of this systematic review and meta-analysis is to evaluate the PT response to exercise in healthy subjects.

Methods

We searched in MEDLINE, EMBASE, Web of Science, Lilacs, and Scopus using a search strategy with the following search terms: "exercise" OR "physical activity" AND "Pain Threshold" from inception to December 2nd, 2019. As criteria for inclusion of appropriate studies: randomized controlled trials or quasi-experimental studies that enrolled healthy subjects; performed an exercise intervention; assessed PT. Hedge's effect sizes of PT response and their 95% confidence intervals were calculated, and random-effects meta-analyses were performed.

Results

For the final analysis, thirty-six studies were included (n=1326). From this we found a significant and homogenous increase in PT in healthy subjects (ES=0.19, 95% CI= 0.11 to 0.27, I2=7.5%). According to subgroup analysis the effect was higher in studies: with women (ES=0.36); performing strength exercise (ES=0.34), and with moderate intensity (ES=0.27), and no differences by age were found. Confirmed by the meta-regression analysis.

Conclusion

This meta-analysis provides evidence of small to moderate effects of exercise on PT in healthy subjects, being even higher for moderate strength exercise and in women. These results support the idea of modulation of the endogenous pain system due to exercise and highlight the need of clinical translation to chronic pain population.

Systemic Exercise-Induced Hypoalgesia Following Isometric Exercise Reduces Conditioned Pain Modulation

Objective

Physically active individuals show greater conditioned pain modulation (CPM) compared with less active individuals. Understanding the effects of acute exercise on CPM may allow for a more targeted use of exercise in the management of pain. This study investigated the effects of acute isometric exercise on CPM. In addition, the between-session and within-session reliability of CPM was investigated.

Design

Experimental, randomized crossover study.

Setting

Laboratory at Marquette University.

Subjects

Thirty healthy adults (19.3±1.5 years, 15 males).

Methods

Subjects underwent CPM testing before and after isometric exercise (knee extension, 30% maximum voluntary contraction for three minutes) and quiet rest in two separate experimental sessions. Pressure pain thresholds (PPTs) at the quadriceps and upper trapezius muscles were assessed before, during, and after ice water immersions.

Results

PPTs increased during ice water immersion (i.e., CPM), and quadriceps PPT increased after exercise (P < 0.05). CPM decreased similarly following exercise and quiet rest (P > 0.05). CPM within-session reliability was fair to good (intraclass correlation coefficient [ICC] = 0.43-0.70), and the between-session reliability was poor (ICC = 0.20-0.35). Due to the variability in the systemic exercise-induced hypoalgesia (EIH) response, participants were divided into systemic EIH responders (N = 9) and nonresponders (N = 21). EIH responders experienced attenuated CPM following exercise (P = 0.03), whereas the nonresponders showed no significant change (P > 0.05).

Conclusions

Isometric exercise decreased CPM in individuals who reported systemic EIH, suggesting activation of shared mechanisms between CPM and systemic EIH responses. These results may improve the understanding of increased pain after exercise in patients with chronic pain and potentially attenuated CPM.

Low intensity blood flow restriction exercise: Rationale for a hypoalgesia effect

Exercise-induced hypoalgesia is characterised by a reduction in pain sensitivity following exercise. Recently, low intensity exercise performed with blood flow restriction has been shown to induce hypoalgesia. The purpose of this manuscript is to discuss the mechanisms of exercise-induced hypoalgesia and provide rationale as to why low intensity exercise performed with blood flow restriction may induce hypoalgesia. Research into exercise-induced hypoalgesia has identified several potential mechanisms, including opioid and endocannabinoid-mediated pain inhibition, conditioned pain modulation, recruitment of high threshold motor units, exercise-induced metabolite production and an interaction between cardiovascular and pain regulatory systems. We hypothesise that several mechanisms consistent with prolonged high intensity exercise may drive the hypoalgesia effect observed with blood flow restriction exercise. These are likely triggered by the high level of intramuscular stress in the exercising muscle generated by blood flow restriction including hypoxia, accumulation of metabolites, accelerated fatigue onset and ischemic pain. Therefore, blood flow restriction exercise may induce hypoalgesia through similar mechanisms to prolonged higher intensity exercise, but at lower intensities, by changing local tissue physiology, highlighting the importance of the blood flow restriction stimulus. The potential to use blood flow restriction exercise as a pain modulation tool has important implications following acute injury and surgery, and for several load compromised populations with chronic pain.

The knitting community-based trial for older women with osteoarthritis of the hands: design and rationale of a randomized controlled trial

BACKGROUND

The prevalence of hand osteoarthritis (HOA) has been reported to be higher amongst women over 50 years old (66%) compared to men of the same age (34%). Although exercise therapy has been shown effective in reducing symptoms and disability associated with HOA, adherence to treatment programs remains low. The primary objective of this RCT is to examine the effectiveness of a 12-week knitting program for morning stiffness (primary outcome) and pain relief (secondary outcome) 2 h post-wakening in females (aged 50 to 85 years old) with mild to moderate hand osteoarthritis (HOA).

METHODS/DESIGN

A single-blind, two-arm randomized controlled trial (RCT) with a parallel group design will be used to reach this objective and compare results to a control group receiving an educational pamphlet on osteoarththritis (OA) designed by the Arthritis Society. The premise behind the knitting program is to use a meaningful occupation as the main component of an exercise program. The knitting program will include two components: 1) bi-weekly 20-min knitting sessions at a senior's club and 2) 20-min home daily knitting sessions for the five remaining weekdays. Participants assigned to the control group will be encouraged to read the educational pamphlet and continue with usual routine. Pain, morning stiffness, hand function, self-efficacy and quality of life will be measured at baseline, six weeks, 12 weeks (end of program) with standardized tools. We hypothesize that participants in the knitting program will have significant improvements in all clinical outcomes compared to the control group. A published case study as well as the preliminary results of a feasibility study as examined through a 6-week pre-post study (n = 5 women with HOA) involving 20-min daily knitting morning sessions led to this proposed randomized controlled trial research protocol. This article describes the intervention, the empirical evidence to support it.

DISCUSSION

This knitting RCT has the potential to enhance our understanding of the daily HOA symptoms control and exercise adherence, refine functional exercise recommendations in this prevalent disease, and reduce the burden of disability in older women.

TRIAL REGISTRATION

(ACTRN12617000843358) registered on 7/06/2017.

A comparison of isometric, isotonic concentric and isotonic eccentric exercises in the physiotherapy management of subacromial pain syndrome/rotator cuff tendinopathy: study protocol for a pilot randomised controlled trial

Background

Subacromial pain syndrome (SPS) involving rotator cuff tendinopathy is a common cause of shoulder pain and disability. Evidence suggests that structured physiotherapy may be as effective as surgery in this condition with significant improvements demonstrated in trials involving scapular retraining, rotator cuff strengthening and flexibility exercises. Most published programs typically utilise isotonic concentric and/or eccentric strengthening modes. Recently, immediate analgesic effects and muscle strength gains following heavy-load isometric exercises in lower limb tendinopathy conditions have been observed. It is pertinent to ascertain whether such outcomes can be replicated in SPS/rotator cuff tendinopathy. The primary aim of this study is to establish the feasibility of undertaking a full-scale randomised controlled trial (RCT) that compares the effects of isometric, isotonic concentric and isotonic eccentric rotator cuff contractions when used as part of a semi-standardised exercise-based physiotherapy program in patients diagnosed with SPS. The secondary aim is to explore potential trends or treatment effects of the exercise intervention.

Methods

Thirty-six participants diagnosed with SPS will be randomised to one of three intervention groups and undergo a one-on-one exercise-based physiotherapy intervention, involving scapular and rotator cuff muscle retraining and strengthening. Each group will utilise a different mode of rotator cuff strengthening—isometric, isotonic concentric or isotonic eccentric. Rotator cuff tendon responses to isometric loading are not yet established in the literature; hence, individualised, progressive loading will be used in this pilot study in accordance with symptoms. The intervention will involve two phases: during Phase 1 (weeks 1–6) participants undertake the active group-specific physiotherapy treatment; in Phase 2 (weeks 6–12), they undertake a progressive, but no longer group-specific exercise program. To determine feasibility, an evaluation of key study parameters including (a) ease of recruitment (rate and number as well as suitability of the assessment algorithm), (b) adherence to all phases of the exercise intervention including home program compliance and logbook completion, (c) participant non-completion (drop out number and rate) and (d) adverse events (nature and number) will be undertaken. Secondary outcomes will measure immediate effects: (i) within-treatment changes in pain perception (verbal rating scale (VRS) and shoulder muscle strength (hand-held dynamometer) as well as longer-term changes: (ii) shoulder-related symptoms and disability (Western Ontario Rotator Cuff Index (WORC) and Shoulder Pain and Disability Index (SPADI)), (iii) perception of pain (11-point numerical rating scale (NRS), (iv) shoulder muscle strength (hand-held dynamometer) and (v) perceived global rating of change score. The immediate within-treatment assessment of pain and muscle strength will be undertaken in treatments 2 and 3, and the longer term measures will be collected at the primary (conclusion of Phase 1 at 6 weeks) and secondary (conclusion of Phase 2 at 12 weeks) end-points of the study.

Discussion

The findings of this pilot study will permit evaluation of this study design for a full-scale RCT.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12616001676404

Electronic supplementary material

The online version of this article (10.1186/s40814-017-0190-3) contains supplementary material, which is available to authorized users.

Psychosocial Influences on Exercise-Induced Hypoalgesia

Objective

The purpose of this study was to examine psychosocial influences on exercise-induced hypoalgesia (EIH).

Design

Randomized controlled trial.

Setting

Clinical research unit in a hospital.

Subjects

Fifty-eight healthy men and women (mean age = 21 ± 3 years) participated in this study.

Methods

Participants were first asked to complete a series of baseline demographic and psychological questionnaires including the Pain Catastrophizing Scale, the Fear of Pain Questionnaire, and the Family Environment Scale. Following this, they were familiarized with both temporal summation of heat pain and pressure pain testing protocols. During their next session, participants completed the Profile of Mood States, rated the intensity of heat pulses, and indicated their pressure pain thresholds and ratings before and after three minutes of submaximal, isometric exercise. Situational catastrophizing was assessed at the end of the experimental session.

Results

Results indicated that experimental pain sensitivity was significantly reduced after exercise ( P  < 0.05). Men and women did not differ on any of the measured psychosocial variables ( P  > 0.05). Positive family environments predicted attenuated pain sensitivity and greater EIH, whereas negative and chronic pain-present family environments predicted worse pain and EIH outcomes. Situational catastrophizing and negative mood state also predicted worse pain and EIH outcomes and were additionally associated with increased ratings of perceived exertion and muscle pain during exercise.

Conclusions

This study provides preliminary evidence that psychosocial variables, such as the family environment and mood states, can affect both pain sensitivity and the ability to modulate pain through exercise-induced hypoalgesia.

Explicit Education About Exercise-Induced Hypoalgesia Influences Pain Responses to Acute Exercise in Healthy Adults: A Randomized Controlled Trial

The mechanisms through which acute exercise reduces pain (ie, exercise-induced hypoalgesia [EIH]) are poorly understood. This study aimed to determine if education about EIH affected pain responses after acute exercise in healthy adults. Participants received 15 minutes of education either about EIH (intervention, n = 20) or more general education about exercise and pain (control, n = 20). After this, the participants' knowledge and beliefs about exercise and pain were assessed. Pressure pain thresholds were then measured before and after 20 minutes of cycle ergometer exercise. Compared with the control group, the intervention group believed more strongly that pain could be reduced by a single session of exercise (P = .005) and that the information they had just received had changed what they thought about the effect of exercise on pain (P = .045). After exercise, pressure pain threshold increased in both groups, but the median increase was greater in the intervention group compared with the control group (intervention = .78 kg/cm², control = .24 kg/cm², P = .002, effect size [r] of difference = .49). These results suggest that cognitive processes in the appraisal of pain can be manipulated to influence EIH in healthy adults.

PERSPECTIVE

This study shows that preceding a bout of exercise with pain education can alter pain responses after exercise. This finding has potential clinical implications for exercise prescription for people with chronic pain whereby pain education before exercise could be used to improve pain responses to that exercise.

Occlusion of blood flow attenuates exercise-induced hypoalgesia in the occluded limb of healthy adults

Animal studies have demonstrated an important role of peripheral mechanisms as contributors to exercise-induced hypoalgesia (EIH). Whether these same mechanisms contribute to EIH in humans is not known. In the current study, pain thresholds were assessed in healthy volunteers ( n = 36) before and after 5 min of high-intensity leg cycling exercise and an equivalent period of quiet rest. Pressure pain thresholds (PPTs) were assessed over the rectus femoris muscle of one leg and first dorsal interosseous muscles (FDIs) of both arms. Blood flow to one arm was occluded by a cuff throughout the 5-min period of exercise (or rest) and postexercise (or rest) assessments. Ratings of pain intensity and pain unpleasantness during occlusion were also measured. Pain ratings during occlusion increased over time (range, 1.5 to 3.5/10, all d > 0.63, P < 0.001) similarly in the rest and exercise conditions ( d < 0.35, P > 0.4). PPTs at all sites were unchanged following rest (range, −1.3% to +0.9%, all d < 0.05, P > 0.51). Consistent with EIH, exercise significantly increased PPT at the leg (+29%, d = 0.69, P < 0.001) and the nonoccluded (+23%, d = 0.56, P < 0.001) and occluded (+8%, d = 0.19, P = 0.003) unexercised arms. However, the increase in the occluded arm was significantly smaller ( d = −1.03, P < 0.001). These findings show that blocking blood flow to a limb during exercise attenuates EIH, suggesting that peripheral factors contribute to EIH in healthy adults.

NEW & NOTEWORTHY This is the first demonstration in humans that a factor carried by the circulation and acting at the periphery is important for exercise-induced hypoalgesia. Further understanding of this mechanism may provide new insight to pain relief with exercise as well as potential interactions between analgesic medications and exercise.

Reduced Modulation of Pain in Older Adults After Isometric and Aerobic Exercise

Laboratory-based studies show that acute aerobic and isometric exercise reduces sensitivity to painful stimuli in young healthy individuals, indicative of a hypoalgesic response. However, little is known regarding the effect of aging on exercise-induced hypoalgesia (EIH). The purpose of this study was to examine age differences in EIH after submaximal isometric exercise and moderate and vigorous aerobic exercise. Healthy older and younger adults completed 1 training session and 4 testing sessions consisting of a submaximal isometric handgrip exercise, vigorous or moderate intensity stationary cycling, or quiet rest (control). The following measures were taken before and after exercise/quiet rest: 1) pressure pain thresholds, 2) suprathreshold pressure pain ratings, 3) pain ratings during 30 seconds of prolonged noxious heat stimulation, and 4) temporal summation of heat pain. The results revealed age differences in EIH after isometric and aerobic exercise, with younger adults experiencing greater EIH compared with older adults. The age differences in EIH varied across pain induction techniques and exercise type. These results provide evidence for abnormal pain modulation after acute exercise in older adults.

PERSPECTIVE

This article enhances our understanding of the influence of a single bout of exercise on pain sensitivity and perception in healthy older compared with younger adults. This knowledge could help clinicians optimize exercise as a method of pain management.

Rotator Cuff Tendinopathy: Navigating the Diagnosis-Management Conundrum

Synopsis The hallmark characteristics of rotator cuff (RC) tendinopathy are pain and weakness, experienced most commonly during shoulder external rotation and elevation. Assessment is complicated by nonspecific clinical tests and the poor correlation between structural failure and symptoms. As such, diagnosis is best reached by exclusion of other potential sources of symptoms. Symptomatic incidence and prevalence data currently cannot be determined with confidence, primarily as a consequence of a lack of diagnostic accuracy, as well as the uncertainty as to the location of symptoms. People with symptoms of RC tendinopathy should derive considerable comfort from research that consistently demonstrates improvement in symptoms with a well-structured and graduated exercise program. This improvement is equivalent to outcomes reported in surgical trials, with the additional generalized benefits of exercise, less sick leave, a faster return to work, and reduced costs to the health care system. This evidence covers the spectrum of conditions that include symptomatic RC tendinopathy and atraumatic partial- and full-thickness RC tears. The principles guiding exercise treatment for RC tendinopathy include relative rest, modification of painful activities, an exercise strategy that initially does not exacerbate pain, controlled reloading, and gradual progression from simple to complex shoulder movements. Evidence also exists for a specific exercise program being beneficial for people with massive inoperable tears of the RC. Education is an essential component of rehabilitation, and attention to lifestyle factors (smoking cessation, nutrition, stress, and sleep management) may enhance outcomes. Outcomes may also be enhanced by subgrouping RC tendinopathy presentations and directing treatment strategies according to the clinical presentation and the patient's response to shoulder symptom modification procedures outlined herein. There are substantial deficits in our knowledge regarding RC tendinopathy that need to be addressed to further improve clinical outcomes. J Orthop Sports Phys Ther 2015;45(11):923-937. Epub 21 Sep 2015. doi:10.2519/jospt.2015.5941.