Intensity thresholds for aerobic exercise-induced hypoalgesia

The effect of stretching intensity on pain sensitivity: A randomized crossover study on healthy adults

BACKGROUND

Stretching exercises have effects on local and widespread pain sensitivity. A dose-response relationship may exist between the analgesic effect and the intensity of stretching, such that a higher intensity of stretching may generate a larger reduction in analgesic response, but this remains to be studied. This study aimed to examine the dose-response relationship between stretching intensity and the analgesic effect.

METHODS

A randomized, repeated-measures crossover study was performed to examine the effect of stretching to the first point of pain onset and stretching to the point of a sensation of stretching (discomfort). The primary outcome was regional and distant pressure pain thresholds.

RESULTS

Thirty-one participants (n = 24 female) were available for analysis. We observed a 22.2% increase in regional pressure pain thresholds (93.2 kPa, p = 0.001) and a 15.0% increase in distant pressure pain thresholds (50.9 kPa, p = 0.012) following stretching to the point of stretch. We observed a 20.0% increase in regional pressure pain thresholds (90.3 kPa, p = 0.001) and a 15.1% increase in distant pressure pain thresholds (52.1 kPa, p = 0.004) following stretching to the point of pain.

CONCLUSIONS

The results showed that local and widespread pain sensitivity decreased following acute stretching, regardless of stretching intensity. No differences in pain sensitivity were found between stretching to the point of stretch or stretching to the first onset of pain. Thus, the results showed no evidence of a dose-response relationship between stretching intensity and the analgesic effect.

SIGNIFICANCE

The study showed a significant acute hypoalgesic effect of stretching exercises regardless of stretching intensity. This may have appropriate clinical implications for patients with musculoskeletal and nociplastic pain.

Ten Minutes of Core Stabilisation Exercise Result in Local Exercise-Induced Hypoalgesia in Patients With Chronic Unspecific Low Back Pain

BACKGROUND

Core stabilisation training is known to be effective in managing pain in patients suffering from chronic low back pain (CLBP). Yet, acute effects of core stabilisation exercise on exercise-induced hypoalgesia (EIH) are largely unknown. This study aimed to examine the EIH effects of an easy-to-perform core stabilisation exercise in CLBP patients and to explore associations between EIH and potential influencing factors (i.e., physical activity, catastrophizing, kinesiophobia, subjective pain state and exercise exertion).

METHODS

Thirty patients with unspecific CLBP finished this randomised controlled crossover trial. Patients performed a 10-min isometric core stabilisation exercise and a 10-min control session. Before and after, pain sensitivity was measured via pressure pain thresholds [Newton/cm2] locally (low back; PPTlocal) and remotely (forehead, thumb; PPTremote). Correlation analyses were performed between EIH and influencing factors.

RESULTS

A 'Time' × 'Intervention' interaction (p < 0.001) was observed for PPTlocal with post hoc analysis revealing higher values post exercise (p < 0.001; pre: 56.6 ± 20.6, post: 67.5 ± 26.1). No differences were observed for the control session (p = 0.894; pre: 58.5 ± 24.0, post: 58.4 ± 23.3). No such effect was observed for PPTremote (p = 0.014). Post hoc analyses showed no differences following the exercise session (p = 0.103; pre: 41.3 ± 12.5, post: 42.5 ± 13.6), while lower PPTremote post values were observed post control compared to pre values (p = 0.031; 42.5 ± 14.5, post: 41.3 ± 13.7). The only significant moderate correlation was observed between ΔPPTlocal of the exercise session and catastrophizing with rho = -0.381.

CONCLUSION

A 10-min isometric core stabilisation exercise results in local lumbar EIH, while no systemic effects are observed. A higher degree of catastrophizing is associated with lower hypoalgesic responses.

SIGNIFICANCE

This study shows for the first time that a brief and easy-to-perform 10-min core stabilisation exercise produces significant local pain relief (EIH) in patients with unspecific CLBP. The effect is localised to the lumbar region, with no observed impact on remote sites. Higher pain catastrophizing seems to be linked to reduced hypoalgesic response. These findings support the use of short core stabilisation exercises as an effective, immediate, non-pharmacological pain management strategy for these patients.

Aerobic Exercise Prescription for Pain Reduction in Fibromyalgia: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVE

Fibromyalgia is a condition characterised by disabling levels of pain of varying intensity. Aerobic exercise may play a role in reducing pain in these patients. The aim of this review is to assess the dose of aerobic exercise needed, based on the frequency, intensity, type, time, volume and progression (FITT-VP) model, to obtain clinically relevant reductions in pain.

DATABASES AND DATA TREATMENT

A systematic review and meta-analysis of randomised clinical trials was conducted in the Web of Science (WoS), PEDro, PubMed and Scopus databases, the search having been conducted between July and October of 2023. Risk of bias was assessed with the Cochrane Risk of Bias assessment tool 2.

RESULTS

Seventeen studies were included. The risk of bias varied, with six studies showing low risk; five, some concerns; and six, high risk. Aerobic exercise interventions were analysed using the FITT-VP model. Frequency ranged from 1 to 10 times per week, intensity varied from light to vigorous, and the types of exercise included music-based exercise, interval training, pool-based exercise, stationary cycling, swimming and walking. The intervention durations ranged from 3 to 24 weeks, with session lengths ranging from 10 to 45 min. Most of the studies presented significant differences, favouring aerobic exercise (MD -0.49; CI [-0.90, -0.08; p = 0.02]), with moderate to low heterogeneity in subgroup analyses.

CONCLUSIONS

The study findings underscore the efficacy of aerobic exercise in alleviating pain among fibromyalgia patients, advocating for tailored exercise dosing to optimise adherence and outcomes.

SIGNIFICANCE STATEMENT

Individuals with fibromyalgia should engage in aerobic exercises two to three times weekly, for twenty-five to forty minutes in each session, aiming for more than a hundred minutes per week. They should start at low intensity, gradually increasing to higher intensities over six to twelve weeks, for optimal pain management. Exercise types should be selected in collaboration with the patient and based on personal preferences and accessibility, such as walking, and swimming, to ensure long-term adherence to the regimen.

Examining Changes in Pain Sensitivity Following 8 Minutes of Cycling at Varying Exercise Intensities

This study assessed the effect of an eight-minute cycling intervention using varying intensities on exercise-induced hypoalgesia (EIH). The main objective of this study was to examine the effect of varying intensities on pressure pain threshold (PPT) and heat pain threshold (HPT) at the thigh and forearm, tested pre- and post-cycling intervention. Healthy male participants (n = 16) performed a graded exercise test on a cycle ergometer to establish their peak power output (PPO). In subsequent visits, participants completed five different 8-minute cycling interventions, with intensities randomly assigned to one of three counterbalanced orders. HPT and PPT were applied to the thigh and forearm two times before and after each cycling intervention. Additionally, there was a notable effect of intensity on PPT in the thigh, with significant changes at intensities of 90% (p = 0.024) and 100% PPO (p = 0.003). In the forearm, repeated measures ANOVA indicated that there was no significant interaction or main effect for intensity and time. Similarly, for HPT, the analysis did not show significant interaction or main effects for both intensity and location. This study was the first to examine EIH using an 8-minute cycling intervention on a cycling ergometer at individualized intensities. Higher intensity cycling sessions generated EIH locally in the thigh using PPT. A short but high intensity cycling intervention may have clinical relevance, as it can provide an intervention to reduce localized pain immediately after exercise using a pressure pain stimulus.

Effects of Apnea-Induced Hypoxia on Hypoalgesia in Healthy Subjects

INTRODUCTION

Exercise-induced hypoalgesia is a phenomenon in which exercise bouts induce a reduction in pain sensitivity. Apnea training involves similar characteristics that could potentially induce hypoalgesia.

OBJECTIVES

The objectives of this study are to explore the effect of apnea training on hypoalgesia; assess the correlation between conditioned pain modulation (CPM) response and apnea-induced hypoalgesia; and examine the association between hypoalgesia with hypoxemia, and heart rate (HR) during apnea.

METHODS

A randomized controlled trial was conducted comparing a walking protocol employing intermittent apnea compared with normal breathing in healthy volunteers. Hypoalgesia was tested with pressure pain thresholds (PPTs) and CPM. Oxygen saturation (SpO2) and HR were also tested.

RESULTS

Relevant but not significant changes were detected in the thumb (MD = 0.678 kg/cm2), and tibialis (MD = 0.718 kg/cm2) in favor of the apnea group. No significant differences were detected in CPM. The apnea group presented lower SpO2, but HR values similar to those of the control group during the intervention. Basal CPM and intrasession hypoxemia significantly correlated with the PPT response. However, HR did not correlate with the PPT response.

CONCLUSIONS

The current results suggest a trend, though not statistically significant, toward an improvement in the PPT in favor of apnea training compared to normal breathing. Nevertheless, subjects who presented greater basal CPM and lower oxygen saturation during the session presented a greater PPT response, suggesting the possibility of mediators of response. Future investigations should clarify this phenomenon.

Relationship Between Frequency of Physical Activity, Functional Mobility, and Self-Perceived Health in People with Different Levels of Pain: A Cross-Sectional Study

Background: Habits including regular physical activity are necessary for maintaining good health. Functional mobility, including walking and going up and down stairs, is essential for personal autonomy and well-being. Pain is a condition related to biological and psychosocial aspects that influence people's lives. Objective: The main objectives of this study were (1) to analyse the associations between physical activity frequency (PAF) and self-perceived health (SPH) and functional mobility (walking and going up and down stairs) in middle-aged and older people living in Spain with different pain levels; and (2) to analyse the risk factors for having a negative SPH and functional mobility difficulties by calculating the probabilistic risks adjusted by different variables (sex, body mass index, social class, civil status, smoking status, pain level, and PAF). Methods: A cross-sectional study based on the European Health Survey data in Spain (EHSS 2014-2020) and The Spanish National Health Survey (SNHS 2017) was carried out, with a final sample of 21,152 participants with ages between 40 and 79 years. Results: Associations between high pain levels and worse SPH and difficulties in walking and climbing stairs were found. Lower PAF levels were associated with higher-probability risks of having a negative SPH and difficulties in walking and climbing stairs. Conclusions: Physical inactivity emerged as an important risk factor for worse SPH and functional mobility. These associations underline the importance that PA programmes can play in the improvement of health and functional mobility, as well as in other aspects, in people with pain.

Technology supported High Intensity Training in chronic non-specific low back pain (the Techno-HIT trial): study protocol of a randomised controlled trial

Chronic low back pain (CLBP) is one of the most common chronic musculoskeletal disorders worldwide. Guidelines recommend exercise therapy (ET) in CLBP management, but more research is needed to investigate specific ET modalities and their underlying mechanisms. The primary goal of this study is to evaluate the short-term and long-term effectiveness of a time-contingent individualised high-intensity training (HIT) protocol on disability compared with a time-contingent moderate-intensity training (MIT) as used in usual care, in persons with severely disabling CLBP. Additionally, the effectiveness on central effects, the added value of prolonged training at home and technology support, and the cost-effectiveness are evaluated. In this randomised controlled trial, CLBP patients will be randomly divided into three groups of 56 participants. Group 1, 'TechnoHIT', receives HIT with technology-support in the home-phase. Group 2, 'HIT', receives HIT without technology support. Group 3, 'MIT', receives MIT, reflecting training intensity as used in usual care. The primary outcome is patient-reported disability, measured by the Modified Oswestry Disability Index. Secondary outcomes include quantitative sensory testing, psychosocial factors, broad physical fitness, quality of life, cost-effectiveness, adherence and usability of technology. Trial registration number NCT06491121.

Effect of Prior Moderate Aerobic Exercise to Prolonged Sitting on Peripheral and Central Cardiovascular Measures in Young Women

BACKGROUND

Prolonged sitting is a risk factor for cardiovascular disease (CVD). We examined whether moderate aerobic exercise prior to prolonged sitting (EX + SIT) has protective effects on peripheral and central cardiovascular and autonomic measures.

METHODS

Young women (n = 26; 23.4 ± 4.3 years old; BMI = 23.1 ± 4.3) completed two sessions in random order: (1) EX + SIT, which consisted of 25 min of moderate aerobic exercise followed by a 3 h prolonged sitting bout, and (2) a 3 h prolonged sitting bout only (SIT-only). Seated peripheral and central blood pressure (BP), pulse wave velocity (PWV), and heart rate variability (HRV) were measured at baseline and after 1 h, 2 h, and 3 h of sitting. Generalized linear mixed models with random effects examined the effects of conditions (i.e., EX + SIT vs. SIT) on BP, PWV, and HRV while adjusting for baseline values.

RESULTS

Only peripheral and central diastolic BP (β = 2.18; p = 0.016 and β = 1.99; p = 0.034, respectively) were significantly lower in the EX + SIT condition compared to the SIT-only condition. No differences were detected in other BP, PWV, or HRV variables between the two conditions (p > 0.05 for all).

CONCLUSIONS

Performing moderate aerobic exercise in the morning before engaging in prolonged sitting bouts may reduce some of the prolonged-sitting-induced cardiovascular impairments in young women. Further research is needed to confirm these findings in males and middle-aged/older adults.

Exercise-induced changes in central sensitization outcomes in individuals with chronic musculoskeletal pain: A systematic review with meta-analysis

BACKGROUND AND OBJECTIVE

Temporal summation of pain (TSP) and conditioned pain modulation (CPM) are the two most commonly used clinical measures of central sensitization (CS). However, the effectiveness of exercise on TSP and CPM has yet to be evaluated. This review aims to investigate the effect of exercise alone on CS outcomes in individuals with chronic musculoskeletal pain.

DATABASES AND DATA TREATMENT

This is a systematic review and meta-analysis. MEDLINE, EMBASE, CINAHL, PEDro and Cochrane databases were searched. Data were extracted based on the exercise modality and grouped into aerobic, resistance, isometric, or motor control modalities. Risk of bias was assessed using RoB2, RoB2 for crossover trials and ROBINS-I tools. Quality of evidence was assessed using GRADE. Random-effects meta-analyses were conducted, with subgroup analysis conducted for each exercise modality.

RESULTS

The meta-analyses included thirteen studies, consisting of eight non-randomized studies, three randomized controlled trials and three randomized crossover trials. Data were categorized into four subgroups for analyses based on exercise modality. No statistically significant effect existed for both TSP and conditioned pain modulation. However, motor control exercise was found to have a significant enhancing effect on conditioned pain modulation. No significant differences were found between the exercise subgroup for both TSP and conditioned pain modulation.

CONCLUSIONS

We did not find an overall effect of physical exercise on TSP and CPM. However, subgroup analysis shows favourable effects of motor control exercise in individuals with chronic neck pain. Future research should focus on exercise modality and dosage and their role in the mechanism involved in TSP and CPM in predefined populations.

SIGNIFICANCE STATEMENT

Results from this study found that motor control exercise has a significant enhancing effect on conditioned pain modulation, with subgroup analysis showing favourable effects of motor control exercise in individuals with chronic neck pain. This indicates that physical exercise may have a positive effect on central sensitisation in individual with chronic neck pain. However, differential effects may exist between different types of exercise. These findings will inform understanding of neurobiological effects underlying chronic neck pain and may guide the development of more effective, personalised treatments.

Exercise induced hypoalgesia after a high intensity functional training: a randomized controlled crossover study

BACKGROUND

Acute physical activity often induces an acute reduction in pain sensitivity known as exercise induced hypoalgesia (EIH). The aim of this study was to investigate the effects of a high intensity functional training (HIFT) on EIH compared to a control session.

METHODS

50 (age: 26.0 ± 2.7; 23 female) participants successfully conducted this study consisting of a pre-experimental test as well as a 12-minute HIFT (body-weight exercises) and a 12-minute control (supervised breathing) session in a randomized crossover design. Pre and post, pressure pain thresholds (PPT) were measured at the ankles, knees, elbows, and forehead.

RESULTS

The HIFT resulted in a relative maximum and average heart rate of 96.2% (± 3.6%) and 91.1% (± 4.2%), respectively, and maximum and average RPE values of 19.1 (± 1.2) and 16.2 (± 1.4), respectively. Results reveal a significant 'Intervention' × 'Time point' interaction (p < 0.001) for PPT (pooled for one average value) with hypoalgesia observed following the HIFT (p < 0.001; pre: 56.0 ± 16.8, post: 61.6 ± 19.0 [Newton]) and no change following the control (p = 0.067; pre: 56.6 ± 18.4, post: 55.3 ± 18.9 [Newton]). Further, a significant 'Time' × 'Intervention' × 'Landmark' interaction effect (p = 0.024) is observed and all landmarks showed significant hypoalgesia following HIFT (p < 0.01), except for the right elbow and forehead. Following control, no hypoalgesia was observed at any landmark. Analysing male and female participants separately, it was observed that EIH occured only in men.

CONCLUSION

A HIFT using bodyweight exercises reduces pain sensitivity. Hence, combining strength and aerobically demanding exercises in a short but high intensity manner, as done in HIFT, can be seen as a usable tool to induce hypoalgesia. Yet, these results were observed only in male participants, necessitating future sex-specific research.

TRIAL REGISTRATION

DRKS00034391, retrospectively registered on the 4th of June 2024.

Rowing and pain: does rowing lead to exercise-induced hypoalgesia?

Physical activity acutely alters pain processing known as exercise-induced hypoalgesia (EIH). This randomized controlled crossover study investigated the effects of two different rowing exercises on EIH and to explore whether possible EIH effects are related to individual rowing specific performance. Fifty male experienced rowers conducted two rowing sessions (submaximal: 30 min of moderate rowing (70% of maximum heart rate); maximal: 350 m in an all-out fashion) and a control session. Pre and post exercise pain sensitivity was measured bilaterally using pressure pain thresholds (PPT; Newton (N)) at the elbow, knee, ankle, sternum, and forehead. Individual performance was determined as maximum watt/kg and was tested for correlations with changes in PPT. Higher PPT values were observed after maximal exercise at all landmarks with a mean change ranging from 2.5 ± 7.8 N (right elbow; p = 0.027; dz = 0.323) to 10.0 ± 12.2 N (left knee; p ≤ 0.001; dz = 0.818). The submaximal (range from -1.6 ± 8.8 N (Sternum; p = 0.205; dz = 0.182) to 2.0 ± 10.3 N (right ankle; p = 0.176; dz = 0.194)) and control session (range from -0.5 ± 7.6 N (left elbow; p = 0.627; dz = 0.069) to 2.6 ± 9.1 N (right ankle; p = 0.054; dz = 0.279)) did not induce changes. Relative performance levels were not correlated to EIH (range from: r = -0.129 (p = 0.373) at sternum to r = 0.176 (p = 0.221) at left knee). EIH occurred globally after a short maximal rowing exercise while no effects occurred after rowing for 30 min at submaximal intensity. EIH cannot be explained by rowing specific performance levels in experienced rowers. However, the sample may lack sufficient heterogeneity in performance levels to draw final conclusions.

Hypoalgesia after aerobic exercise in healthy subjects: A systematic review and meta-analysis

Exercise-Induced Hypoalgesia (EIH) refers to an acute reduced pain perception after exercise. This systematic review and meta-analysis investigated the effect of a single aerobic exercise session on local and remote EIH in healthy individuals, examining the role of exercise duration, intensity, and modality. Pressure pain thresholds (PPT) are used as the main measure, applying the Cochrane risk of bias tool and GRADE approach for certainty of evidence assessment. Mean differences (MD; Newton/cm²) for EIH effects were analysed. Thirteen studies with 23 exercises and 14 control interventions are included (498 participants). Most studies used bicycling, with only two including running/walking and one including rowing. EIH occurred both locally (MD = 3.1) and remotely (MD = 1.8), with high-intensity exercise having the largest effect (local: MD = 7.5; remote: MD = 3.0) followed by moderate intensity (local: MD = 3.1; remote: MD = 3.0). Low-intensity exercise had minimal impact. Neither long nor short exercise duration induced EIH. Bicycling was found to be effective in eliciting EIH, in contrast to the limited research observed in other modalities. The overall evidence quality was moderate with many studies showing unclear risk biases.

The Role of Physical Exercise in Chronic Musculoskeletal Pain: Best Medicine-A Narrative Review

The aim of this paper is to provide a narrative review of the effects of physical exercise in the treatment of chronic musculoskeletal pain. Physical inactivity and sedentary behavior are associated with chronic musculoskeletal pain and can aggravate it. For the management of musculoskeletal pain, physical exercise is an effective, cheap, and safe therapeutic option, given that it does not produce the adverse effects of pharmacological treatments or invasive techniques. In addition to its analgesic capacity, physical exercise has an effect on other pain-related areas, such as sleep quality, activities of daily living, quality of life, physical function, and emotion. In general, even during periods of acute pain, maintaining a minimum level of physical activity can be beneficial. Programs that combine several of the various exercise modalities (aerobic, strengthening, flexibility, and balance), known as multicomponent exercise, can be more effective and better adapted to clinical conditions. For chronic pain, the greatest benefits typically occur with programs performed at light-to-moderate intensity and at a frequency of two to three times per week for at least 4 weeks. Exercise programs should be tailored to the specific needs of each patient based on clinical guidelines and World Health Organization recommendations. Given that adherence to physical exercise is a major problem, it is important to empower patients and facilitate lifestyle change. There is strong evidence of the analgesic effect of physical exercise in multiple pathologies, such as in osteoarthritis, chronic low back pain, rheumatoid arthritis, and fibromyalgia.

Effects of a Therapeutic Exercise Protocol for Patients with Chronic Non-Specific Back Pain in Primary Health Care: A Single-Group Retrospective Cohort Study

BACKGROUND

Back pain is highly prevalent; in Spain, it produces a very high economic cost and the scientific evidence supporting treatments shows low to moderate evidence for exercise. Therefore, the aim of this study was to assess the effectiveness of a therapeutic group exercise protocol in reducing pain intensity and disability in patients with back pain in primary health care setting.

METHODS

A total sample of 149 patients who suffered from chronic non-specific back pain was selected. Patients received a therapeutic exercise protocol, including auto-mobilization exercises for the neck and lumbar regions, as well as core stabilization exercises. Pain intensity and disability were evaluated before and after the therapeutic exercise protocol.

RESULTS

Statistically significant differences (p < 0.05) were shown in pain intensity and disability for patients with non-specific neck and low-back pain, with an effect size from moderate to large.

CONCLUSIONS

A therapeutic exercise protocol may provide beneficial effects upon disability and pain intensity in patients with chronic non-specific back pain, including neck and low-back pain conditions In addition, It could be considered for inclusion as a back-pain-approach program in primary healthcare.

Modulation of pain perceptions following treadmill running with different intensities in females

We aimed to compare the effects of three intensities of treadmill running on exercise-induced hypoalgesia (EIH) in healthy individuals. We anticipated that the primary and secondary changes in pain perception and modulation may differ between running intensities. Sixty-six women were randomly assigned to one of three treadmill running intensities for 35 min: 40% reserved heart rate (HRR), 55% HRR, or 70% HRR. The effects of EIH were assessed using pressure pain thresholds (PPT) and tolerance thresholds (PPTol). We measured conditional pain modulation (CPM). Compared with baseline, PPT and PPTol significantly increased in all groups during running and at the 5-10-min follow-up. The PPT and PPTol changes in the moderate- and low-intensity groups were significantly higher than those in the high-intensity group during running and 24 h after running, while the CPM responses of the high-intensity group were significantly reduced at the 24-h follow-up. Moderate- and low-intensity running may elicit significant primary and secondary (persisting over 24 h) EIH effects and increase CPM responses in females. However, high-intensity running induced only limited analgesic effects and reduced CPM responses, which may be attributed to the activation of endogenous pain modulation.

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. PERSPECTIVE: This 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.

Assessment of exercise-induced hypoalgesia in chronic low back pain and potential associations with psychological factors and central sensitization symptoms: A case-control study

INTRODUCTION

Exercise is the most recommended treatment for chronic low back pain (CLBP) and is effective in reducing pain, but the mechanisms underlying its effects remain poorly understood. Exercise-induced hypoalgesia (EIH) may play a role and is thought to be driven by central pain modulation mechanisms. However, EIH appears to be disrupted in many chronic pain conditions and its presence in people with CLBP remains unclear. As people suffering from chronic pain often exhibit psychological factors and central sensitization symptoms influencing pain perception, EIH might be associated with these factors.

OBJECTIVE

The aim of this study is to compare the level of EIH between participants with and without CLBP following back and wrist exercises and to assess the associations between EIH, psychological factors, and symptoms of central sensitization (using the central sensitization inventory - CSI) in CLBP.

METHOD

Twenty-eight participants with CLBP and 23 without pain were recruited. Pressure pain thresholds (PPT) were measured at 4 sites (2 bony sites = capitate, S1|2 muscle sites = wrist flexors, lumbar erector spinae) before and after each of two exercises (wrist flexion and lumbar extension). Exercise-induced hypoalgesia was defined as percent change in PPT from pre- to post-exercise. Participants with CLBP also completed questionnaires to measure psychological factors (e.g., kinesiophobia, catastrophizing, anxiety, and self-efficacy) and symptoms of central sensitization (CSI), and correlations with EIH were calculated.

RESULTS

After wrist exercise, EIH measured at the muscle sites was lower in the CLBP group compared with the pain-free group (p = 0.047) but no differences were found at bony sites (p = 0.49). No significant differences for EIH were observed following back exercise at muscle sites (p = 0.14) or at bony sites (p = 0.65). Exercise-induced hypoalgesia was not correlated with any psychological factors or with the CSI score.

CONCLUSION

The lower EIH following wrist exercises may represent an alteration in pain modulation control in CLBP. However, psychological factors and central sensitization symptoms may not explain the differences observed.

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.

Does Exercise-Induced Hypoalgesia Depend on Exercise Duration?

Acute physical activity is assumed to lead to exercise-induced hypoalgesia (EIH). Yet, little research has been conducted dealing with the influence of exercise duration on EIH. The aim of this study was to investigate the effects of three different exercise durations using the same intensity compared to a control session on EIH. A total of 36 participants conducted three different exercise sessions on a bicycle ergometer for 30, 45, and 60 min, respectively, in addition to a passive control session. The intensity was set to 75% of the individual's VO₂max. Pre and post exercise, pain sensitivity was measured employing pressure pain thresholds (PPT) at the elbow, knee, and ankle joints, as well as the sternum and forehead. In addition, the conditioned pain modulation (CPM) response was conducted pre and post exercise. The results reveal that the exercises neither led to any changes in PPT measured at any landmark nor induced any CPM response effects. These results do not confirm the hypoalgesic effects usually observed after exercise. The reasons explaining these results remain rather elusive but might be explained by the low intensities chosen leading to a milder release of pain inhibiting substances, the landmarks employed for PPT measurements, or potential non-responsiveness of participants.

Perceived Pain in Athletes: A Comparison between Endurance Runners and Powerlifters through a Cold Experimental Stimulation and Two Sessions of Various Physical Activation

Few studies in the literature have illustrated cold hypoalgesia induced by strength training. Objectives of this contribution were to compare the ratings of perceived pain in endurance running (n = 22) and powerlifting (n = 22) male athletes and controls (n = 22) at baseline and after two bouts of 40 min aerobic/strength training respectively, using the Cold Pressor Test (CPT) and simultaneously monitoring changes in blood pressure (BP), heart rate (HR), and body temperature. A two-way repeated measures ANOVA was conducted to examine the effects of training sessions in endurance runners vs. powerlifting athletes vs. controls on the intensity of perceived pain at CPT. A statistically significant two-way interaction between the group and training resulted in p < 0.001, ηp2 = 0.513. A simple main effects analysis showed that as the participants went through the strength training session, pain perception at CPT was significantly lower in powerlifters compared to runners and controls. Considering the physiological parameters, powerlifters reported significantly higher values of BP and HR. This difference was present at baseline but after training as well, and before and after CPT, despite a slight hypotensive effect. The differences reported after CPT at baseline, but very significantly after the strength activation session in the powerlifters, provide interesting insights into the hypoalgesic effect of high-intensity strength training.

Effects of Exercise-Induced Hypoalgesia at Different Aerobic Exercise Intensities in Healthy Young Adults

PURPOSE

Exercise-induced hypoalgesia (EIH) is a reduction in pain sensitivity that occurs following a single bout of exercise. However, little research has compared the EIH effects of exercise at different intensities, including low intensity, in the same participant. It is unclear as to which exercise intensities demonstrate EIH more effectively. The aim of this study was to examine and compare the effect of different intensities of exercise on pain sensitivity in the same participant.

METHODS

We included 73 healthy young adult volunteers (35 female and 38 male) in this experimental cross-over study. Each participant completed four experimental sessions of 30 min, consisting of aerobic exercise at 30% heart rate reserve (HRR), aerobic exercise at 50% HRR, aerobic exercise at 70% HRR, and quiet rest. EIH was assessed using the pressure pain threshold (PPT) and temporal summation of pain (TSP) in the quadriceps, biceps, and trapezius.

RESULTS

Low- and moderate-intensity exercise increased the multisegmental PPT and reduced TSP (all P < 0.05). High-intensity exercise increased the multisegmental PPT (all P < 0.05), but decreased TSP in only the quadriceps and biceps (P < 0.05), not the trapezius (P = 0.13). We found no difference in relative PPT and TSP changes between exercise intensities (P > 0.05) except for relative PPT change at the quadriceps (P < 0.05).

CONCLUSION

Our results show that not only moderate- and high-intensity exercise, but also low-intensity exercise can produce a hypoalgesic response.

Effect of Physiotherapeutic Interventions on Biomarkers of Neuropathic Pain: A Systematic Review of Preclinical Literature

The purpose of this systematic review was to evaluate the effects of physiotherapeutic interventions on biomarkers of neuropathic pain in preclinical models of peripheral neuropathic pain (PNP). The search was performed in Pubmed, Web of Science, EMBASE, Cochrane, Cinhal, Psycinfo, Scopus, Medline, and Science Direct. Studies evaluating any type of physiotherapy intervention for PNP (systemic or traumatic) were included. Eighty-one articles were included in this review. The most common PNP model was chronic constriction injury, and the most frequently studied biomarkers were related to neuro-immune processes. Exercise therapy and Electro-acupuncture were the 2 most frequently studied physiotherapy interventions while acupuncture and joint mobilization were less frequently examined. Most physiotherapeutic interventions modulated the expression of biomarkers related to neuropathic pain. Whereas the results seem promising; they have to be considered with caution due to the high risk of bias of included studies and high heterogeneity of the type and anatomical localization of biomarkers reported. The review protocol is registered on PROSPERO (CRD42019142878). PERSPECTIVE: This article presents the current evidence about physiotherapeutic interventions on biomarkers of neuropathic pain in preclinical models of peripheral neuropathic pain. Existing findings are reviewed, and relevant data are provided on the effectiveness of each physiotherapeutic modality, as well as its certainty of evidence and clinical applicability.

Exercise-induced hypoalgesia (EIH) in response to different exercise intensities

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.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00421-022-04997-1.

The Influence of Exercise Intensity on Psychosocial Outcomes in Musculoskeletal Disorders: A Systematic Review

CONTEXT

Psychosocial parameters play an important role in the onset and persistence of chronic musculoskeletal disorders (CMSDs). Exercise therapy is a valuable therapeutic modality as part of CMSD rehabilitation. Hereby, exercise intensity is an important factor regarding changes in pain and disability in multiple CMSDs. However, the impact of exercise intensity on psychosocial outcomes remains poorly explored.

OBJECTIVE

To identify the effects of different modes of exercise intensity on psychosocial outcomes in persons with CMSDs.

DATA SOURCES

A systematic search was conducted up to November 2020 using the following databases: PubMed/MEDline, PEDro, Cochrane Library, and Web of Science.

STUDY SELECTION

Studies reporting exercise therapy in CMSDs with a predefined display of exercise intensity and an evaluation of at least 1 psychosocial outcome were included.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 2a.

DATA EXTRACTION

Data regarding demographics, exercise intensity, and psychosocial outcomes were included in a descriptive analysis. Methodological quality was assessed using the PEDro scale and Critical Appraisal Skills Programme (CASP) checklist.

RESULTS

A total of 22 studies, involving 985 participants (with fibromyalgia, chronic low back pain, knee osteoarthritis, psoriatic arthritis, and axial spondyloarthritis) were included (mean PEDro score = 5.77/10). The most common psychosocial outcomes were quality of life (QoL) (n = 15), depression (n = 10), and anxiety (n = 9). QoL improved at any exercise intensity in persons with fibromyalgia. However, persons with fibromyalgia benefit more from exercising at low to moderate intensity regarding anxiety and depression. In contrast, persons with chronic low back pain benefit more from exercising at a higher intensity regarding QoL, anxiety, and depression. Other CMSDs only showed limited or conflicting results regarding the value of certain exercise intensities.

CONCLUSION

Psychosocial outcomes are influenced by the intensity of exercise therapy in fibromyalgia and chronic low back pain, but effects differ across other CMSDs. Future research is necessary to determine the exercise intensity that yields optimal exercise therapy outcomes in specific CMSDs.

Muscle-brain communication in pain: The key role of myokines

Pain is the most common reason for a physician visit, which accounts for a considerable proportion of the global burden of disease and greatly affects patients' quality of life. Therefore, there is an urgent need to identify new therapeutic targets involved in pain. Exercise-induced hypoalgesia (EIH) is a well known phenomenon observed worldwide. However, the available evidence demonstrates that the mechanisms of EIH remain unclear. One of the most accepted hypotheses has been the activation of several endogenous systems in the brain. Recently, the concept that the muscle acts as a secretory organ has attracted increasing attention. Proteins secreted by the muscle are called myokines, playing a critical role in communicating with other organs, such as the brain. This review will focus on several myokines and discuss their roles in EIH.

Effects of Therapeutic and Aerobic Exercise Programs on Pain, Neuromuscular Activation, and Bite Force in Patients with Temporomandibular Disorders

Pain in masticatory muscles is one of the most frequent symptoms in patients with temporomandibular disorders (TMD) and can lead to changes in the patterns of neuromuscular activity of masticatory muscles and decrease in bite force. This study assesses the effects of three eight-week exercise programs on pain intensity, neuromuscular activation, and bite force of masticatory muscles in patients with TMD. Forty-five patients were divided into three groups: a therapeutic exercise program (G1), a therapeutic and aerobic exercise program (G2), and an aerobic exercise program (G3). The masticatory muscles’ pain was evaluated using the numeric pain rating scale (NPRS), surface electromyographic (sEMG) activity of the masseter was recorded during maximum voluntary contraction and at rest, and bite force was evaluated using a dynamometer. These parameters were evaluated twice at baseline (A01/A02), at the end of the eight-week intervention period (A1), and 8–12 weeks after the end of the intervention (A2). After intervention, G2 showed the best results, with a significantly decrease in masticatory muscles’ pain and increase in bite force. These results suggest that interventions to reduce pain in patients with TMD should be multimodal.

Aerobic exercise with blood flow restriction causes local and systemic hypoalgesia and increases circulating opioid and endocannabinoid levels

This study examined the effect of aerobic exercise with and without blood flow restriction (BFR) on exercise-induced hypoalgesia and endogenous opioid and endocannabinoid systems. In a randomized crossover design, pain-free individuals performed 20 min of cycling in four experimental trials: 1) low-intensity aerobic exercise (LI-AE) at 40% V̇o_2max; 2) LI-AE with low-pressure BFR (BFR40); 3) LI-AE with high-pressure BFR (BFR80); and 4) high-intensity aerobic exercise (HI-AE) at 70% V̇o_2max. Pressure pain thresholds (PPTs) were assessed before and 5 min postexercise. Circulating concentrations of beta-endorphin and 2-arachidonoylglycerol were assessed before and 10 min postexercise. In the exercising legs, postexercise PPTs were increased following BFR40 and BFR80 compared with LI-AE (23-32% vs. 1-2% increase, respectively). The increase in PPTs was comparable to HI-AE (17-20% increase) with BFR40 and greater with BFR80 (30-32% increase). Both BFR80 and HI-AE increased PPTs in remote areas of the body (increase of 26-28% vs. 19-21%, respectively). Postexercise circulating beta-endorphin concentration was increased following BFR40 (11%) and HI-AE (14%), with the greatest change observed following BFR80 (29%). Postexercise circulating 2-arachidonoylglycerol concentration was increased following BFR40 (22%) and BFR80 (20%), with the greatest change observed following HI-AE (57%). Addition of BFR to LI-AE can trigger both local and systemic hypoalgesia that is not observed follow LI-AE alone and activate endogenous opioid and endocannabinoid systems of pain inhibition. Compared with HI-AE, local and systemic hypoalgesia following LI-AE with high-pressure BFR is greater and comparable, respectively. LI-AE with BFR may help pain management in load-compromised individuals.NEW & NOTEWORTHY We have shown that performing blood flow restriction (BFR) during low-intensity aerobic exercise can trigger local and systemic hypoalgesia, which is not typically observed with this intensity of exercise. High-pressure BFR triggers greater and comparable hypoalgesia than high-intensity aerobic exercise in the exercising limbs and remote areas of the body, respectively. Performing BFR during low-intensity aerobic exercise activates the opioid and endocannabinoid systems, providing novel insight into potential mechanisms of hypoalgesia with BFR exercise.

Aerobic Exercise Attenuates Pain Sensitivity: An Event-Related Potential Study

In this study, electroencephalography (EEG) was utilized to explore the neurophysiological mechanisms of aerobic exercise-induced hypoalgesia (EIH) and provide a theoretical basis for the application of aerobic exercise in pain assessment and treatment. Forty-five healthy subjects were randomly divided into moderate-intensity aerobic exercise [70% heart rate reserve (HRR)], low-intensity aerobic exercise (50% HRR), or control groups (sitting). Aerobic exercise was performed with cycling. Pressure pain threshold (PPT), heat pain threshold (HPT), event-related potential (ERP) induced by contact heat stimulus and pain scoring were measured before and after the intervention. We found that moderate-intensity aerobic exercise can increase the PPT (rectus femoris: t = -2.71, p = 0.017; tibialis anterior muscle: t = -2.36, p = 0.033) and HPT (tibialis anterior muscle: t = -2.219, p = 0.044) of proximal intervention sites rather than distal sites, and decreased pain scorings of contact heat stimulus. After moderate-intensity aerobic exercise, alpha oscillation power reflecting the central descending inhibitory function was enhanced (t = -2.31, p < 0.05). Low-intensity aerobic exercise mainly reduced the pain unpleasantness rating (Block 1: t = 2.415, p = 0.030; Block 2: t = 3.287, p = 0.005; Block 4: t = 2.646, p = 0.019; Block 5: t = 2.567, p = 0.022). Aerobic exercise had an overall EIH effect. Its hypoalgesic effect was related to exercise intensity and affected by the site and type of pain stimulus. Moderate-intensity aerobic exercise effectively reduced the sensitivity to various painful stimuli, and low-intensity aerobic exercise selectively inhibited the negative emotional pain response. The hypoalgesic mechanism of aerobic exercise involves the enhancement of the central descending inhibitory function.

The effect of exercise intensity on exercise-induced hypoalgesia in cancer survivors: A randomized crossover trial

Pain is experienced by people with cancer during treatment and in survivorship. Exercise can have an acute hypoalgesic effect (exercise-induced hypoalgesia; EIH) in healthy individuals and some chronic pain states. However, EIH, and the moderating effect of exercise intensity, has not been investigated in cancer survivors. This study examined the effect of low- and high-intensity aerobic exercise on EIH in cancer survivors after a single exercise session as well as a brief period of exercise training (2-weeks, three exercise sessions per week). Participants (N = 19) were randomized to low- (30%-40% Heart Rate Reserve (HRR) or high- (60%-70% HRR) intensity stationary cycling for 15-20 min. Pressure pain thresholds (PPT) were assessed over the rectus femoris and biceps brachii before and after a single exercise session and again after a short training period at the assigned intensity. Then, following a 6-week washout period, the intervention was repeated at the other intensity. After the first exercise session, high-intensity exercise resulted in greater EIH over the rectus femoris than low intensity (mean difference ± SE: -0.51 kg/cm2  ± 0.15, Cohen's d = 0.78, p = 0.004). After a 2-week training period, we found no difference in EIH between intensities (0.01 kg/cm2  ± 0.25, d = 0.00 p = 0.99), with comparable moderate effect sizes for both low- and high-intensity exercise, indicative of EIH. No EIH was observed over the biceps brachii of the arm at either low or high intensity. Low-intensity exercise training may be a feasible option to increase pain thresholds in cancer survivors.

Effects of therapeutic exercise and aerobic exercise programmes on pain, anxiety and oral health-related quality of life in patients with temporomandibular disorders

BACKGROUND

Pain and anxiety contribute to decreasing quality of life related to oral health in patients with temporomandibular disorders (TMD). Evidence-based practice has shown that therapeutic and aerobic exercise programmes are adequate strategies for modifying these factors.

OBJECTIVE

To assess the effects of aerobic exercise on pain, anxiety and quality of life related to oral health in patients with TMD.

METHODS

Forty-five patients diagnosed with TMD were divided into three groups of 15 participants: a therapeutic exercise programme (G1, mean 26.9 ± 5.5 years), a therapeutic and aerobic exercise programme (G2, mean 26 ± 4.4 years) and an aerobic exercise programme (G3, mean 24.9 ± 3.4 years). Pain intensity was assessed using a numerical rating scale (NRS), anxiety level and quality of life related to oral health through GAD-7 and OHIP-14, respectively. These parameters were evaluated twice at baseline (T0a/T0b), ending 8-week intervention period (T1) and 8-12 weeks after ending intervention (T2).

RESULTS

NRS significantly decreased in G1 (mean difference T0a/T1 = 5.2, p ˂ .001), G2 (mean difference T0a/T1 = 6.0, p ˂ .001) and G3 (mean difference T0a/T1 = 2.2, p = 0.001). OHIP-14 significantly decreased in G1 (mean difference T0a/T1 = 13.5, p ˂ .001) and G2 (mean difference T0a/T1 = 15.8, p ˂ 0.001) but not in G3 (mean difference T0a/T1 = 1.2, p = 0.55). There were no significant differences between groups regarding GAD-7. Between T1 and T2, there were no significant differences in variables.

CONCLUSION

Therapeutic exercises and therapeutic excercises combined with aerobic exercise groups had a significant decrease in pain and oral health-related quality of life at 8 and 12 weeks. These decreases were not seen for the aerobic exercise group.

Acute effect of strength training on pain in women with fibromyalgia: A brief report

OBJECTIVE

The aim was to analyze the effect of one session and three sessions of strength training (ST) on pain in women with fibromyalgia (FM).

METHOD

Twenty-three women with FM performed three sessions of ST for a week. Each training session worked the main muscle groups and lasted 60 min. Three sets of 12 repetitions were performed with 1 min intervals in between. The load was increased based on the perception of subjective effort of each patient. Pain intensity was evaluated immediately after the first and third sessions using a Fischer digital algometer.

RESULTS

After the first ST session, pain reduction was observed. No significant differences were found in pain thresholds on the baseline versus the third session. The analysis of MBI demonstrated that the ST does not worsen patients' pain, indicating a 52.2% trivial effect and a 39.1% beneficial effect.

CONCLUSION

Our results suggest that there is no harmful effect on the pain of women with FM after an acute session of ST. We emphasize that despite the promising results, more studies on the subject are needed to help understand pain in patients with FM.

The influence of pain, kinesiophobia and psychological comorbidities on the accuracy of rating of perceived exertion in UK military spinal rehabilitation

INTRODUCTION

Chronic low back pain (CLBP) is a leading cause of disability in the UK Military. Pain and psychological comorbidities have been reported to influence the rating of perceived exertion (RPE). Exercise rehabilitation can be monitored using RPE; however, the accuracy of RPE in inpatient CLBP rehabilitation is unknown.

METHODS

A prospective cohort correlation study of 40 UK Military inpatients with CLBP was completed. Disability (ODI), kinesiophobia (TSK), anxiety (GAD-7) and depression (PHQ-9) were subjectively reported at the beginning and end of a 3 week intervention. Pain (VAS) and HR were recorded in the first aerobic exercise (AE) session (T1) and the final aerobic exercise session (T2). RPE was reported for each AE session.

RESULTS

At T1, a positive correlation was observed between RPE accuracy (-7.2±20.9), and pre-exercise pain (2.7 mm ±1.6 mm) (p>0.001) and ODI (31.0±16.9) (p>0.05), and a negative relationship between RPE accuracy and average HR (135 bpm ±22 bpm) (p>0.001) was observed. At T2, there was no significant correlation between RPE accuracy (-4.4±22.6) and pre-exercise pain (2.8 mm ±1.6 mm) or ODI (34.0±16.5) (p>0.05). The strong negative relationship between RPE accuracy and average HR (137 bpm ±20 bpm) remained at T2. Improved RPE accuracy over the 3-week rehabilitation programme was correlated to the change in average HR (r=-0.314, p<0.05).

CONCLUSIONS

Comorbidities may negatively affect RPE accuracy in CLBP, but the magnitude of the influence reduces over intensive rehabilitation.

Are endogenous opioid mechanisms involved in the effects of aerobic exercise training on chronic low back pain? A randomized controlled trial

Aerobic exercise is believed to be an effective chronic low back pain (CLBP) intervention, although its mechanisms remain largely untested. This study evaluated whether endogenous opioid (EO) mechanisms contributed to the analgesic effects of an aerobic exercise intervention for CLBP. Individuals with CLBP were randomized to a 6-week, 18-session aerobic exercise intervention (n = 38) or usual activity control (n = 44). Before and after the intervention, participants underwent separate laboratory sessions to assess responses to evoked heat pain after receiving saline placebo or intravenous naloxone (opioid antagonist) in a double-blinded, crossover fashion. Chronic pain intensity and interference were assessed before and after the intervention. Endogenous opioid analgesia was indexed by naloxone-placebo condition differences in evoked pain responses (blockade effects). Relative to controls, exercise participants reported significantly greater pre-post intervention decreases in chronic pain intensity and interference (Ps < 0.04) and larger reductions in placebo condition evoked pain responsiveness (McGill Pain Questionnaire-Short Form [MPQ]-Total). At the group level, EO analgesia (MPQ-Total blockade effects) increased significantly pre-post intervention only among female exercisers (P = 0.03). Dose-response effects were suggested by a significant positive association in the exercise group between exercise intensity (based on meeting heart rate targets) and EO increases (MPQ-Present Pain Intensity; P = 0.04). Enhanced EO analgesia (MPQ-Total) was associated with a significantly greater improvement in average chronic pain intensity (P = 0.009). Aerobic exercise training in the absence of other interventions appears effective for CLBP management. Aerobic exercise-related enhancements in endogenous pain inhibition, in part EO-related, likely contribute to these benefits.

Does isometric exercise result in exercise induced hypoalgesia in people with local musculoskeletal pain? A systematic review

OBJECTIVE

The aim of this review was to investigate if exercise induced hypoalgesia (EIH) occurs following isometric muscle contraction in people with local musculoskeletal symptoms.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE, EMBASE, CINAHL & SportDiscus electronic databases were searched (inception to April 2020).

ELIGIBILITY CRITERIA

Two authors independently evaluated eligibility. Randomised controlled and crossover (repeated measures) trials that measured the effects of isometric exercise in participants with localised musculoskeletal pain during, and up to 2 hours after isometric exercise were included. Other inclusion criteria included comparison to another intervention, or comparison to healthy controls. Primary outcomes were experimentally induced pain thresholds and secondary outcomes included measures of pain sensitivity from clinical testing.

RESULTS

13 studies with data from 346 participants were included for narrative synthesis. EIH was reported in some upper and lower limb studies but there were no consistent data to show isometric exercises were superior to comparison interventions.

CONCLUSION

There was no consistent evidence for EIH following isometric exercise in people with musculoskeletal pain. These findings are different to those reported in asymptomatic populations (where EIH is consistently demonstrated) as well as conditions associated with widespread symptoms such as fibromyalgia (where isometric exercise may induce hyperalgesia). Although well tolerated when prescribed, isometric exercise did not induce EIH consistently for people seeking care for local musculoskeletal symptoms. The variance in the dose, location of contraction and intensity of protocols included in this review may explain the inconsistent findings. Further work is required to better understand endogenous analgesia in musculoskeletal pain conditions.

Acute Effects of a Brief Physical Exercise Intervention on Somatosensory Perception, Lumbar Strength, and Flexibility in Patients with Nonspecific Chronic Low-Back Pain

BACKGROUND

Evidence-based clinical guidelines consider physical exercise one of the best nonpharmacological interventions for low-back pain (LBP), but it is necessary to clarify the exercise-induced hypoalgesia effect of different modalities of exercise in chronic pain populations.

PURPOSE

This study focused on exploring acute changes in tactile and pressure-pain perception and lumbar strength and flexibility in patients with nonspecific chronic LBP (NSCLBP) after performing one of three 20-minute physical exercise modalities.

METHODS

A total of 81 patients with NSCLBP were pseudorandomly distributed into three groups of 20-minute physical exercise - 1) aerobic (n=21, mean age 42±9.72 years, nine men), 2) stretching (n=21, mean age 40±11.37 years, ten men), and 3) strengthening (n=20, mean age 35.80±11.56 years, ten men) - and 4) a control group (n=19, mean age 38.64±10.24 years, eight men), and completed self-reported questionnaires during the same period. Tactile and pressure-pain thresholds and isometric lumbar muscle endurance and flexibility were assessed before and after this brief exercise-based intervention.

RESULTS

All groups were comparable in terms of sociodemographic and clinical data, cardiovascular capacity, and self-reported data onphysical disability, mood, motivation, psychological response to stimulus properties of physical exercise, and physical activity enjoyment. Our analyses revealed higher tactile sensitivity (p<0.001) and pressure-pain thresholds (p<0.001) at the forefinger than other body locations. We also found lower pain sensitivity (p=0.010) and pressure pain-intensity ratings (p=0.001) and higher lumbar flexibility (p<0.001) after intervention. After calculation of absolute pre-post differences, higher tactile sensitivity was observed at the gluteus medius muscle than the erector spinal muscle only after aerobic intervention (p=0.046).

CONCLUSION

These results add some evidence about different modalities of exercise-induced hypoalgesia in NSCLBP. However, the fact that we also found improvements in the control group limits our conclusions.

Interrelated hypoalgesia, creep, and muscle fatigue following a repetitive trunk flexion exposure

Repetitive trunk flexion can damage spinal tissues, however its association with low back pain in the workplace may be confounded by factors related to pain sensitivity. Muscle fatigue, exercise-induced hypoalgesia, and creep-induced neuromuscular changes following repetitive trunk flexion may all affect this assumed exposure-pain relationship. This study's purpose was to determine how mechanical pain sensitivity in the low back is affected by a repetitive trunk flexion exposure and identify factors associated with changes in low back pain sensitivity. Pressure pain thresholds, perceptions of sub-threshold stimuli, and muscle fatigue in the trunk and tibia, as well as lumbar spine creep were tracked in 37 young healthy adults before and up to 40 min after a 10-min repetitive trunk flexion exposure. Pressure pain thresholds (p = 0.033), but not perceptions of sub-threshold stimuli (p > 0.102) were associated with approximately a 12.5% reduction in pain sensitivity 10 min after completing the exposure, while creep and local muscle fatigue effects were only observed immediately following the exposure. Creep and fatigue interactions and the corresponding tibial measure co-varied with individual low back pressure pain thresholds. The net hypoalgesic effects of repetitive trunk flexion have the potential to partially mask possibly injurious loads, which could contribute to the severity or incidence of lower back injuries related to these exposures.

The tolerance to stretch is linked with endogenous modulation of pain

OBJECTIVES

The effect of stretching on joint range of motion is well documented, and although sensory perception has significance for changes in the tolerance to stretch following stretching the underlining mechanisms responsible for these changes is insufficiently understood. The aim of this study was to examine the influence of endogenous pain inhibitory mechanisms on stretch tolerance and to investigate the relationship between range of motion and changes in pain sensitivity.

METHODS

Nineteen healthy males participated in this randomized, repeated-measures crossover study, conducted on 2 separate days. Knee extension range of motion, passive resistive torque, and pressure pain thresholds were recorded before, after, and 10 min after each of four experimental conditions; (i) Exercise-induced hypoalgesia, (ii) two bouts of static stretching, (iii) resting, and (iv) a remote, painful stimulus induced by the cold pressor test.

RESULTS

Exercise-induced hypoalgesia and cold pressor test caused an increase in range of motion (p<0.034) and pressure pain thresholds (p<0.027). Moderate correlations in pressure pain thresholds were found between exercise-induced hypoalgesia and static stretch (Rho>0.507, p=0.01) and exercise-induced hypoalgesia and the cold pressor test (Rho=0.562, p=0.01). A weak correlation in pressure pain thresholds and changes in range of motion were found following the cold pressor test (Rho=0.460, p=0.047). However, a potential carryover hypoalgesic effect may have affected the results of the static stretch.

CONCLUSIONS

These results suggest that stretch tolerance may be linked with endogenous modulation of pain. Present results suggest, that stretch tolerance may merely be a marker for pain sensitivity which may have clinical significance given that stretching is often prescribed in the rehabilitation of different musculoskeletal pain conditions where reduced endogenous pain inhibition is frequently seen.

A training program for fibromyalgia management: A 5-year pilot study

We studied the effects of a specific cardio training program lasting 5 years on pain and quality of life in fibromyalgia patients.

Effects of transcranial direct current stimulation followed by exercise on neuropathic pain in chronic spinal cord injury: a double-blinded randomized controlled pilot trial

STUDY DESIGN

Double-blinded randomized controlled pilot trial.

OBJECTIVES

The present study aimed to investigate the effects of multiple sessions of tDCS followed by exercise on neuropathic pain and brain activity in individuals with chronic SCI.

SETTING

Rehabilitation center in Taipei, Taiwan.

METHODS

Twelve individuals with neuropathic pain after SCI were randomized into the experimental (real) or control (sham) tDCS group. All participants received 12 sessions of real or sham tDCS, and moderate upper body exercises over 4-6 weeks. Pain intensity, characters of pain, self-rating change of pain, brain activity, and quality of life were assessed at pre, posttest, and 4-week follow-up.

RESULTS

The between-group differences (95% CI) of pain intensity at posttest and at 4-week follow-up were -2.2/10 points (-3.0 to 1.0, p = 0.060) and -2.0/10 points (-5.0 to -0.4, p = 0.035), respectively. The between-group differences of paresthesia/dysesthesia pain character were -2.0/10 points (-3.2 to 1.0, p = 0.053) at posttest and -2.3/10 points (-5.0 to 2.5, p = 0.054) at follow-up. No significant changes in brain activity and quality of life were noted at post-intervention and follow-up in both groups.

CONCLUSIONS

The multiple sessions of anodal tDCS combined with moderate upper body exercise were feasible for individuals with neuropathic pain after spinal cord injury. However, the analgesic effect was not superior to exercise alone after 12 sessions of intervention, and the beneficial effect was observed at 4-week follow-up.

Assessing Endogenous Pain Inhibition: Test-Retest Reliability of Exercise-Induced Hypoalgesia in Local and Remote Body Parts After Aerobic Cycling

OBJECTIVE

Acute exercise can trigger a hypoalgesic response (exercise-induced hypoalgesia [EIH]) in healthy subjects. Despite promising application possibilities of EIH in the clinical context, its reliability has not been sufficiently examined. This study therefore investigated the between-session and within-subject test-retest reliability of EIH at local and remote body parts after aerobic cycling at a heart rate-controlled intensity.

METHODS

Thirty healthy adults (15 women) performed 15 minutes of aerobic cycling in two sessions. Pressure pain thresholds (PPTs) were assessed at the leg (local), the back (semilocal), and the hand (remote) before, immediately after, and 15 minutes after exercise. Intraclass correlation coefficients (ICCs) were calculated for absolute and percent changes in PPT from baseline to immediately postexercise, and between-session agreement of EIH responders was examined.

RESULTS

PPTs significantly increased at the leg during both sessions (all P < 0.001) and at the back during session 2 (P < 0.001), indicating EIH. Fair between-session reliability was shown for absolute changes at the leg (ICC = 0.54) and the back (ICC = 0.40), whereas the reliability of percent changes was poor (ICC < 0.33). Reliability at the hand was poor for both absolute and percent changes (ICC < 0.33). Agreement in EIH responders was not significant for EIH at the leg or the back (all P > 0.05).

CONCLUSIONS

Our results suggest fair test-retest reliability of EIH after aerobic cycling for local and semilocal body parts, but only in men, demonstrating the need for more standardized methodological approaches to improve EIH as a clinical parameter.

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.

Transcranial Direct Current Stimulation Accelerates The Onset of Exercise-Induced Hypoalgesia: A Randomized Controlled Study

Exercise-induced hypoalgesia (EIH) describes acute reductions in pain that occur following exercise. Current evidence suggests that the magnitude of EIH is small-to-moderate at best, warranting exploration of novel avenues to bolster these effects. Transcranial direct current stimulation (tDCS) has been shown to relieve pain and represents a promising intervention that may enhance EIH. This study aimed to determine whether anodal tDCS of the primary motor cortex (M1) can augment EIH in healthy individuals experiencing experimentally-induced musculoskeletal pain. Twenty-four healthy subjects attended 2 experimental sessions ("Day 0" and "Day 2"). On Day 0, subjects were injected with nerve growth factor into their right extensor carpi radialis brevis to induce persistent elbow pain. On Day 2, each subject received active or sham tDCS over M1 followed by an isometric grip exercise. Pain intensity, muscle soreness, sensitivity (pressure pain thresholds), and conditioned pain modulation were assessed prior to the nerve growth factor injection, on Day 2 before tDCS, immediately post-exercise, and 15 minutes post-exercise. Active tDCS expedited the onset of EIH, inducing immediate reductions in pain intensity that were not present until 15 minutes post-exercise in the sham group. However, active tDCS did not reduce muscle soreness or sensitivity when compared to sham tDCS. PERSPECTIVE: These findings suggest that active tDCS accelerates the onset of EIH in healthy individuals experiencing experimentally-induced pain. This may represent a promising means of enhancing adherence to exercise protocols. However, larger randomised controlled trials in persistent pain populations are required to confirm the clinical impact of these findings.

Potential efficacy of sensorimotor exercise program on pain, proprioception, mobility, and quality of life in diabetic patients with foot burns: A 12-week randomized control study

BACKGROUND

Both diabetes mellitus (DM) and burn injuries lead to physical and psychological impairments. Foot burns are still a challenging health condition because of its important sensory role. No previous studies have assessed the physical therapy intervention on diabetic patients with foot burns. Therefore, this study aimed to assess the potential efficacy of sensorimotor exercise on pain, proprioception, mobility, balance, and quality of life in diabetic patients with foot burns.

METHODS

Between July 2019 and February 2020, thirty-three diabetic patients with foot burns, aged 32 to 46yrs, were enrolled in this randomized control study, and randomized consecutively into two groups, study group (n=16) and control group (n=17). The study group underwent a sensorimotor exercise program thrice a week for 12 consecutive weeks, however the control group did not undergo the exercise intervention. Both groups were instructed to conduct home exercises. Visual analogue scale (VAS), proprioceptive responses, time-up and go (TUG) values, and short form-36 (SF-36) have been assessed prior and subsequent to the study intervention.

RESULTS

No significant differences were observed between groups regarding baseline data (p˃0.05). Subsequent to 12wk intervention, the study group showed significant improvements in outcome measures (proprioceptive responses, p˂0.05, VAS, p˂0.001, TUG, p=0.003, and SF-36, p˂0.001) and the control group exhibited significant changes in VAS and SF-36 (p=0.004, p=0.043 respectively) however, no significant changes were found in proprioceptive responses and TUG values (p˃0.05). Between groups, the post-intervention comparison demonstrated statistical differences with tending toward the study group (proprioceptive responses, p˂0.05, VAS, p˂0.001, TUG, p=0.013, and SF-36, p=0.046).

CONCLUSIONS

Sensorimotor exercise training may improve, pain, proprioceptive responses, mobility, balance, and quality of life in diabetic patients with foot burns. Physiotherapists and rehabilitation providers should include the sensorimotor exercise in their protocols in the treatment of diabetic patients with foot burns.

Effect of different exercise training intensities on musculoskeletal and neuropathic pain in inactive individuals with type 2 diabetes - Preliminary randomised controlled trial

AIMS

People with type 2 diabetes (T2D) have a greater prevalence of musculoskeletal and neuropathic pain. This exploratory analysis investigated whether exercise of different intensities leads to changes in self-reported musculoskeletal pain or symptoms of diabetic neuropathy in inactive individuals with type 2 diabetes.

METHODS

Thirty-two inactive adults with T2D (59% male, mean age 58.7 ± 9.1yrs, median HbA_1c 7.8%) were randomised to usual care (CON), supervised combined aerobic and resistance moderate-intensity continuous training (C-MICT), or supervised combined high-intensity interval training (C-HIIT). At baseline and 8-weeks, musculoskeletal and neuropathic pain were evaluated using a modified Nordic Musculoskeletal Questionnaire and the Neuropathy Total Symptom Score-6 respectively. Quantitative sensory testing was used to determine thermal, mechanical and vibration detection thresholds, as well as pain pressure thresholds. Adverse events were recorded throughout the intervention.

RESULTS

Compared to CON, reduction in musculoskeletal pain intensity was significantly greater for C-HIIT (MD -5.4, 95% CI [-10.6 to -0.2], p = 0.04) and non-significantly greater for C-MICT (MD -5.9 [-12.4 to 0.7], p = 0.08). Changes in neuropathy symptoms were not different between C-HIIT and CON (MD 1.0 [-0.9 to 2.8], p = 0.31), or C-MICT and CON (MD 0.2 [-3.1 to 3.6], p = 0.89). No differences in sensory function were observed between groups. Similar rates of adverse events were seen in both exercise interventions (19 C-HIIT; 17 C-MICT), all but one of which were mild.

CONCLUSIONS

Preliminary data suggests 8-weeks of high-intensity combined aerobic and resistance exercise may be safely prescribed for inactive individuals with T2D and may reduce musculoskeletal pain but not neuropathic symptoms.

TRIAL REGISTRATION

ACTRN12615000475549.

The Association of Psychosocial Factors and Exercise-Induced Hypoalgesia in Healthy People and People With Musculoskeletal Pain: A Systematic Review

BACKGROUND

Exercise, a cornerstone in current treatments for people with musculoskeletal pain, elicits a phenomenon called exercise-induced hypoalgesia (EIH), which may result in reduced pain intensity and/or increased pain thresholds. However, EIH can be impaired in patients with musculoskeletal pain, and psychosocial factors may play a mediating role in EIH.

OBJECTIVE

The aim of this study was to systematically review the scientific literature regarding the association between psychosocial factors and EIH in healthy people and people with musculoskeletal pain.

METHODS

An extensive search in databases including Medline Ovid, Embase, Web of Science, PsycINFO Ovid, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) EBSCOhost was carried out. Two reviewers independently carried out study selection, data extraction, and critical appraisal. Included studies analyzed the association or effect of psychosocial factors on EIH in adults with or without musculoskeletal pain.

RESULTS

Nine cross-sectional studies were included, 6 involving healthy people and 4 involving people with musculoskeletal pain; 1 study included both. Overall risk of bias was high. Different types of exercise bouts, psychosocial factors, and/or outcome measures were used across studies. In healthy people and people with musculoskeletal pain, most studies did not find an association between psychosocial factors and EIH. However, 1 study involving musculoskeletal pain and 2 studies with healthy people did find a significant association.

CONCLUSION

Due to poor quality and heterogeneity between studies, no conclusions can be drawn regarding whether psychosocial factors are associated with EIH or not. This review includes recommendations and directions for further research to investigate the role of psychosocial factors on EIH.

Does intensive interdisciplinary pain treatment improve pediatric headache-related disability?

Purpose: To examine the effectiveness of intensive interdisciplinary pain treatment for improving disability in children with chronic headache using the International Classification of Functioning, Disability and Health model as a conceptual framework for disability assessment.Materials and methods: Children with chronic headache (n = 50; ages 10-19 years; 62% female) attended an intensive interdisciplinary pain treatment program 8 h/day, 5 times/week for 2-7 weeks. Disability measures were administered at admission, discharge, and 6-8 week follow-up. Disability outcomes were analyzed retrospectively. Wilcoxon signed rank tests and Friedman's analyses of variance were used to compare scores across two and three longitudinal time points, respectively.Results: After rehabilitation, disability reduced on the Headache Impact Test-6 from severe impact at admission to some impact at follow-up (p < 0.001). Median time on the modified Bruce protocol increased from 13.1 min (interquartile range = 12.6-14.1) to 14.4 min (interquartile range = 12.9-16.3), p < 0.001, with gains maintained at follow-up. Improvements in pain and disability were associated with improvements in school participation.Conclusions: Findings of this study support the effectiveness of intensive interdisciplinary pain treatment for improving disability in children with chronic headache.Implication for rehabilitationIntensive interdisciplinary pain treatment is effective for improving pain and disability in children with chronic headaches.Application of the ICF model to disability assessment suggests that children with chronic headaches may experience significant disability, even when standardized assessments of physical capacity are normal.The modified Bruce protocol, Pediatric Evaluation of Disability Inventory - Computerized Adaptive Tests, and Headache Impact Test-6 appear particularly valuable in understanding the nature of disability in children with chronic headaches.

LOWER EXTREMITY AEROBIC EXERCISE AS A TREATMENT FOR SHOULDER PAIN

BACKGROUND

Shoulder girdle pain is a common disabling complaint with a high lifetime prevalence. Interventions aimed at decreasing shoulder pain without stressing shoulder girdle structures have the potential to improve participation in multimodal shoulder rehabilitation programs.

HYPOTHESIS/PURPOSE

The aim of this study was to determine the acute effects of moderate intensity lower extremity exercise on mechanically induced shoulder pain in individuals without shoulder injury. It was hypothesized that participants would exhibit less shoulder pain, as indicated by increased pain thresholds, following lower extremity exercise.

STUDY DESIGN

Repeated measures study.

METHODS

Thirty (30) healthy participants were recruited to participate in this study. Pain pressure algometry was used to mechanically induce shoulder pain over the infraspinatus muscle belly. This was performed on the dominant shoulder before and immediately after performing 10 minutes of moderate intensity lower extremity exercise using a recumbent exercise machine. Heart rate and rate of perceived exertion were measured following exercise. Repeated measures ANOVA was used to compare pain pressure threshold scores between the baseline and post-exercise time points. Significance was set at p ≤ 0.05 a priori. Effect size (ES) was calculated using Glass's Δ.

RESULTS

Moderate intensity lower extremity aerobic exercise led to significantly (F = 8.471, p = 0.003) decreased evoked shoulder pain in healthy adults with moderate effect sizes (0.30-0.43).

CONCLUSIONS

Lower extremity aerobic exercise significantly decreased pain of the infraspinatus in this sample of young healthy participants. Utilization of lower extremity exercise may be of benefit for younger patients to decreased acute shoulder pain.

LEVEL OF EVIDENCE

2b: individual cohort study.