Effect of indomethacin on the development of eccentric exercise-induced localized sensitive region in the fascia of the rabbit

Delayed-Onset Muscle Soreness Alters Mechanical Sensitivity, but Not Thermal Sensitivity or Pain Modulatory Function

Introduction

Many clinical musculoskeletal pain conditions are characterized by chronic inflammation that sensitizes nociceptors. An unresolved issue is whether inflammation affects all nociceptors in a similar manner. Exercise-induced muscle damage (EIMD) has been proposed as a model for simulating clinical inflammatory pain in healthy samples. We sought to test the effect of EIMD on various painful stimuli (pressure and thermal), central pain processing (via the nociceptive flexion reflex) and endogenous pain modulation via conditioned pain modulation and exercise-induced hypoalgesia.

Methods

Eighteen participants (9F, age: 24.6 ± 3.3) were recruited for repeated measures testing and each completed pain sensitivity testing prior to and 48 hours after an eccentric exercise protocol. The participants performed a minimum of 6 rounds of 10 eccentric knee extension exercises to induce muscle damage and localized inflammation in the right quadriceps. Force decrements, knee range-of-motion, and delayed onset muscle soreness (DOMS) were used to quantify EIMD.

Results

There was a significant main effect of time for pressure pain (%diff; -58.9 ± 23.1; p = 0.02, ηp2 = 0.28) but no significant main effect was observed for limb (%diff; -15.5 ± 23.9; p = 0.53, ηp2 = 0.02). In contrast, there was a significant interaction between time and limb (p < 0.001, ηp2 = 0.47) whereby participants had lower pressure pain sensitivity in the right leg only after the damage protocol (%diff; -105.9 ± 29.2; p = 0.002).

Discussion

Individuals with chronic inflammatory pain usually have an increased sensitivity to pressure, thermal, and electrical stimuli, however, our sample, following muscle damage to induce acute inflammation only had sensitivity to mechanical pain. Exercise induced inflammation may reflect a peripheral sensitivity localized to the damaged muscle rather than a global sensitivity like those with chronic pain display.

Neurochemical mechanism of muscular pain: Insight from the study on delayed onset muscle soreness

We reviewed fundamental studies on muscular pain, encompassing the characteristics of primary afferent fibers and neurons, spinal and thalamic projections, several muscular pain models, and possible neurochemical mechanisms of muscle pain. Most parts of this review were based on data obtained from animal experiments, and some researches on humans were also introduced. We focused on delayed-onset muscle soreness (DOMS) induced by lengthening contractions (LC), suitable for studying myofascial pain syndromes. The muscular mechanical withdrawal threshold (MMWT) decreased 1-3 days after LC in rats. Changing the speed and range of stretching showed that muscle injury seldom occurred, except in extreme conditions, and that DOMS occurred in parameters without muscle damage. The B2 bradykinin receptor-nerve growth factor (NGF) route and COX-2-glial cell line-derived neurotrophic factor (GDNF) route were involved in the development of DOMS. The interactions between these routes occurred at two levels. A repeated-bout effect was observed in MMWT and NGF upregulation, and this study showed that adaptation possibly occurred before B2 bradykinin receptor activation. We have also briefly discussed the prevention and treatment of DOMS.

Clinical effectiveness of trigger point acupuncture on chronic neck and shoulder pain (katakori) with work productivity loss in office workers: a randomized clinical trial

OBJECTIVES

To evaluate whether trigger point acupuncture (TrPA) is beneficial for office workers who have reduced job performance (presenteeism) due to chronic neck and shoulder pain (katakori).

METHODS

A 4-week single-center randomized controlled trial was conducted on 20 eligible female office workers with chronic neck and shoulder pain of at least 3-month duration. The control group implemented only workplace-recommended presenteeism measures, whereas the intervention group received TrPA up to 4 times per month in addition to the presenteeism measures recommended by each workplace. The major outcome measure was the relative presenteeism score on the World Health Organization Health and Work Performance (WHO-HPQ). The secondary outcome measures were pain intensity (numerical rating scale), absolute presenteeism (WHO-HPQ), anxiety and depression (Hospital Anxiety and Depression Scale; HADS), catastrophic thoughts related to pain (Pain Catastrophizing Scale; PCS), and sleep (Athens Insomnia Scale; AIS).

RESULTS

All 9 cases in the intervention group and 11 cases in the control group were analyzed. TrPA up to 4 times per month reduced the intensity of neck and shoulder pain by 20% (P < .01, d = 1.65) and improved labor productivity (relative presenteeism value) by 0.25 (P < .01, d = 1.33) compared with the control group over 1 month. No significant differences were observed between the 2 groups in terms of absolute presenteeism score, HADS, PCS, or AIS.

CONCLUSIONS

These results suggest that regular intervention with TrPA may be effective in the relative presenteeism score before and after the intervention and the degree of neck and shoulder pain over 28 days compared with the control group.

Effects of Photobiomodulation and Low-Intensity Stretching on Delayed-Onset Muscle Soreness: A Randomized Control Trial

Objective: This study aimed to investigate the effects of photobiomodulation (PBM), low-intensity stretching, and their combination on delayed-onset muscle soreness (DOMS) in the untrained population. The relationships between DOMS and muscle function and functional performance were also tested. Methods: Fifty-four participants were randomized into four groups. Eccentric exercise was used to induce DOMS. Each group received either no treatment, PBM, stretching or PBM combined with stretching at 24, 48, and 72 h postexercise. Pressure pain threshold (PPT), numerical rating scale (NRS), single-leg forward jump (SLFJ), and maximum isometric voluntary contraction (MIVC) were measured at baseline, 24, 48, 72, and 96 h after eccentric exercise. Between-group differences were tested using two-way repeated measures analysis of variance and the relationships between DOMS and MIVC, and SLFJ were examined using Pearson's correlation analysis. Results: The PPT at the vastus medialis and vastus lateral in the PBM combined with stretching group was significantly lower than that in control group at 72 h (p = 0.045) and 48 h (p = 0.037) postexercise. No significant between-group difference in PPT was found for the rest occasions. There was no significant between-group difference in NRS, MVIC, and SLFJ on any occasion (p ≥ 0.052). DOMS was not correlated with MIVC and SLFJ (p ≥ 0.09). Conclusions: PBM or low-intensity stretching did not affect DOMS and functional performance in untrained individuals. The combination of PBM and low-intensity stretching increased pain sensitivity and did not relieve soreness. The DOMS was not associated with either muscle function or functional performance.

Pressure pain threshold map of thoracolumbar paraspinal muscles after lengthening contractions in young male asymptomatic volunteers

This study aimed to characterise topographic distribution of pressure pain thresholds (PPTs) of thoracolumbar paraspinal muscles and its change after lengthening contractions (LCs) of the back muscles. Using young male asymptomatic participants in Experiment 1, we systematically examined the distribution of PPTs bilaterally in the range of Th1–L5 at measurement points 2 and 4 cm from the midline. PPTs were found to be higher in the lumbar segments of the paraspinal muscles than in the thoracic segments, and in muscles closer to the vertebrae (2 vs. 4 cm from the midline). The PPTs did not differ between the left and right sides in each segment. In Experiment 2, LC was applied by asking a part of participants recruited in Experiment 1 to fall their trunk from a starting position (parallel to the floor) to 40° flexed position, and then made it back as quickly as possible to the starting position. This cycle was repeated until participants could not keep contractions (30 times/set, 25.4 ± 10.6 sets). PPTs of the LC group decreased prominently in the lower thoracic and lumbar segments, and the decrease was more evident 24 h after LC compared to that 48 h after. In contrast, PPTs in the control group without LC remained unchanged. These results provided broad topographic images of PPTs in the thoracolumbar paraspinal muscles of young male participants with and without LC, and the obtained PPT maps could be a useful guide for better treatment of exercise-induced myofascial pain in the lower back.

In vivo methodologies to assist preclinical development of topical fixed-dose combinations for pain management

The combination in a fixed dose of two or more active pharmaceutical ingredients in the same pharmaceutical dosage form is an approach that has been used successfully in the treatment of several pathologies, including pain. In the preclinical development of a topical fixed-dose combination product with analgesic and anti-inflammatory activities for pain management, the main objective is to establish the nature of the interaction between the different active pharmaceutical ingredients while obtaining data on the medicinal product safety and efficacy. Despite the improvement of in vitro assays, animal models remain a fundamental strategy to characterise the interaction, efficacy and safety of active pharmaceutical ingredients at the physiological level, which cannot be reached by in vitro assays. Thus, the main goal of this review is to systematise the available animal models to evaluate the efficacy and safety of a new fixed-dose combination product for topical administration indicated for pain management. Particular emphasis is given to animal models that are accepted for regulatory purposes.

Effect of Quercetin on Injury to Indomethacin-Treated Human Embryonic Kidney 293 Cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to treat inflammation and pain and even to prevent the progression of cardiovascular disease. They have become widely used because of their effectiveness, especially among athletes performing high-intensity training. Indomethacin is used for pain management in sports medicine and is highly effective and versatile. However, several clinical studies have reported that indomethacin induces acute renal damage. In the present study, we determined that indomethacin reduced human embryonic kidney 293 (HEK293) cell viability in a concentration-dependent manner by triggering apoptosis. In addition, we demonstrated the effect of quercetin on indomethacin-treated HEK293 cells by inactivating the caspase-3 and caspase-9 signals. Furthermore, quercetin reduced ROS production and increased mitochondrial membrane potential (ΔΨm) in indomethacin-treated HEK293 cells. Our results indicate that quercetin can interrupt the activated caspase and mitochondrial pathway induced by indomethacin in HEK293 cells and affect apoptotic mRNA expression. Quercetin can protect against indomethacin-induced HEK293 cell apoptosis by regulating abnormal ΔΨm and apoptotic mRNA expression.

Efficacy of the Combination of Indomethacin and Methocarbamol versus Indomethacin Alone in Patients with Acute Low Back Pain: A Double-Blind, Randomized Placebo-Controlled Clinical Trial

Objective:

Acute low back pain is a common ailment and causes pain and disability. Physicians often prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) to treat acute low back pain; however, due attention has recently been drawn to muscle relaxants to reduce the severity of patients' daily physical dysfunction. Therefore, this study aimed to evaluate the therapeutic effect of the administration of indomethacin alone compared with methocarbamolas a muscle relaxant and indomethacin as an NSAID on the treatment of acute low back pain.

Methods:

The present double-blind clinical trial was performed on 64 patients with acute low back pain. The patients were categorized into two groups and received the treatments as follows. Indomethacin capsules of 25 mg every 8 h and placebo tablets every 8 h were administered in the first group (Group I). Indomethacin capsules of 25 mg every 8 h and methocarbamol tablets of 500 mg every 8 h were administered in the second group (Group I + M). Patient pain intensity and physical function based on Back Pain Function Scale (BPFS) were recorded before and 1 week after the intervention.

Findings:

The present study results revealed that the mean pain reduction of patients in Group I + M was significantly higher than that of Group I (3.66 ± 3.17 vs. 1.84 ± 1.53; P < 0.001). Moreover, the mean BPFS increase in Group I + M was significantly higher than that of Group I (19.44 ± 8.66 vs. 4.75 ± 4.35; P < 0.001).

Conclusion:

According to the results of the present study, concomitant administration of indomethacin and methocarbamol can be more effective in reducing pain intensity and improving the patient's physical function (or performance).

Nonsteroidal anti-inflammatory drugs and acetaminophen ameliorate muscular mechanical hyperalgesia developed after lengthening contractions via cyclooxygenase-2 independent mechanisms in rats

Nonsteroidal anti-inflammatory drugs and acetaminophen are cyclooxygenase inhibitors commonly used as symptomatic medicines for myofascial pain syndrome. Using the selective inhibitors celecoxib and zaltoprofen, cyclooxygenase-2 has been shown to be involved in the initiation, but not the maintenance, of muscular mechanical hyperalgesia induced by lengthening contractions, which serves as a useful model for the study of myofascial pain syndrome. The effect of other cyclooxygenase-2 inhibitors, such as acetylsalicylic acid, ibuprofen, loxoprofen sodium, and acetaminophen, on muscular mechanical hyperalgesia during maintenance has not been studied. Here, we examined the analgesic effects of the nonsteroidal anti-inflammatory drugs and acetaminophen on the model. Consistent with previous studies, mechanical withdrawal threshold of the muscle was significantly decreased and reached its lowest level 24 h after lengthening contractions. Celecoxib had no effect on muscular mechanical hyperalgesia, when orally administered 24 h after lengthening contractions. In contrast, acetylsalicylic acid, ibuprofen, loxoprofen sodium, and acetaminophen increased the withdrawal threshold, which had decreased by lengthening contractions, in a dose-dependent manner. These results demonstrate the analgesic actions of nonsteroidal anti-inflammatory drugs and acetaminophen in the maintenance process of lengthening contraction-induced muscular mechanical hyperalgesia, which may occur through cyclooxygenase-2 independent mechanisms.

Mechanisms of Action of Acupuncture for Chronic Pain Relief – Polymodal Receptors Are the Key Candidates

Therapeutic benefits of acupuncture for chronic pain patients have been clearly identified in recent clinical trials. Underlying mechanisms of acupuncture action mediated by endogenous opioids have been well demonstrated. The existence of pain inhibitory systems in the central nervous system has also been clarified and acupuncture seems to be a potent stimulus for activating the analgesic systems, although the pain mechanisms in acute and chronic states are essentially different. On the other hand, the exact nature of the acupuncture point still remains unclear. Here, we propose a key role of polymodal receptors (PMR) in acupuncture and moxibustion and offer a rational explanation of the acupuncture point as a sensitised PMR.

Moxibustion (burning of moxa) therapy has been shown by medical historians to predate the use of acupuncture, and the meridian theory developed in association with moxibustion treatment. A variety of sensory receptors are activated by acupuncture and/or moxibustion, but there are very few that can be excited by both stimuli. PMRs are one of the most promising candidates. The functional characteristics of PMRs correspond with those of acupuncture action in the periphery; and tender or trigger points, one of the primitive features of acupuncture points, are assumed to be the sites of sensitised PMRs. Diffuse noxious inhibitory control (DNIC) is proposed as a possible mechanism of immediate action of acupuncture, and inputs for the development of DNIC seem to be the PMRs.

In our experimental model, repeated eccentric contractions of muscle produced local tenderness at the palpable band and induced a typical referred pain pattern on application of pressure. Repeated indomethacin injections inhibited the production of the experimental trigger point.

These lines of evidence suggest that the acupuncture points are the sites where the PMRs are sensitised and that such conditions might be repeatedly produced by various biomechanical stressors, insufficient blood supply and metabolic products.

Trigger Point Acupuncture for Treatment of Knee Osteoarthritis – a Preliminary Rct for a Pragmatic Trial

Background

There is evidence for the efficacy of acupuncture treatment in knee osteoarthritis, but it remains unclear which acupuncture modes are most effective. We evaluated the effects of trigger point acupuncture on pain and quality of life in knee osteoarthritis patients, compared with acupuncture at standard points, and sham acupuncture.

Methods

Thirty patients (27 women, 3 men; aged 61–82 years) with non-radiating knee osteoarthritis pain for at least six months and normal neurological examination were randomised to one of three groups for the study period of 21 weeks. Each group received five acupuncture treatment sessions. The standard acupuncture point group ( n=10) received treatment at traditional acupuncture points for knee pain; the trigger point acupuncture group ( n=10) received treatment at trigger points; and the third group ( n=10) received sham acupuncture treatment at the trigger points. Outcome measures were pain intensity (visual analogue scale, VAS) and WOMAC index (Western Ontario and McMaster Universities Arthritis Index). The groups were compared by the area under the curve method.

Results

Five patients dropped out of the study because of lack of improvement, and one patient (in the trigger point acupuncture group) dropped out because of deterioration of symptoms; the remaining 24 patients were included in the analysis. After treatment, the trigger point acupuncture group reported less pain intensity on VAS than the standard acupuncture or sham treatment group, but both the trigger point acupuncture and standard acupuncture groups reported improvement of function of knee. There was a significant reduction in pain intensity between pre-treatment and five weeks after treatment for the trigger point acupuncture (P<0.01) and standard acupuncture groups (P<0.01) included in the analysis, but not for the sham treatment group. Group comparison using the area under the curves demonstrated a significant difference only between trigger point acupuncture and sham treatment groups analysed (P<0.025 for VAS, and P<0.031 for WOMAC).

Conclusion

These results suggest that trigger point acupuncture therapy may be more effective for osteoarthritis of the knee in some elderly patients than standard acupuncture therapy.

Comparison of the Efficiency of Ultrasound-Guided Injections of the Rhomboid Major and Trapezius Muscles in Myofascial Pain Syndrome: A Prospective Randomized Controlled Double-blind Study

OBJECTIVES

We aimed to investigate the effect of ultrasound (US)-guided injections of the rhomboid major (deep) and trapezius (superficial) muscles on pain, disability, and quality of life in patients with myofascial pain syndrome.

METHODS

In this prospective randomized controlled double-blind study, 65 patients with a diagnosis of myofascial pain syndrome were randomized into 2 groups. In group 1 (n = 33), US-guided rhomboid major muscle injection was performed, and in group 2 (n = 32), US-guided trapezius muscle injection was performed. The patients were assessed by a visual analog scale for pain, the Pressure Pain Threshold, the Neck Pain and Disability Scale, and Short Form 12. Data were obtained before treatment (week 0), the second week after treatment, and the fourth week after treatment.

RESULTS

In both groups, significant improvements were observed for all parameters at both weeks 2 and 4 compared to pretreatment values (P < .05). A comparison of the groups showed significantly superior results in group 1 for all parameters at week 2 (P < .05) and for all parameters but the Physical Component Scale of Short Form 12 at week 4 (P < .05).

CONCLUSIONS

We think that US-guided deep injection of the rhomboid major muscle was more effective than superficial injection of the trapezius muscle for pain, disability, and quality of life in patients with myofascial pain syndrome.

Delayed onset muscle soreness: Involvement of neurotrophic factors

Delayed-onset muscle soreness (DOMS) is quite a common consequence of unaccustomed strenuous exercise, especially exercise containing eccentric contraction (lengthening contraction, LC). Its typical sign is mechanical hyperalgesia (tenderness and movement related pain). Its cause has been commonly believed to be micro-damage of the muscle and subsequent inflammation. Here we present a brief historical overview of the damage-inflammation theory followed by a discussion of our new findings. Different from previous observations, we have observed mechanical hyperalgesia in rats 1-3 days after LC without any apparent microscopic damage of the muscle or signs of inflammation. With our model we have found that two pathways are involved in inducing mechanical hyperalgesia after LC: activation of the B2 bradykinin receptor-nerve growth factor (NGF) pathway and activation of the COX-2-glial cell line-derived neurotrophic factor (GDNF) pathway. These neurotrophic factors were produced by muscle fibers and/or satellite cells. This means that muscle fiber damage is not essential, although it is sufficient, for induction of DOMS, instead, NGF and GDNF produced by muscle fibers/satellite cells play crucial roles in DOMS.

An MRI-based leg model used to simulate biomechanical phenomena during cuff algometry: a finite element study

Cuff pressure stimulation is applicable for assessing deep-tissue pain sensitivity by exciting a variety of deep-tissue nociceptors. In this study, the relative transfer of biomechanical stresses and strains from the cuff via the skin to the muscle and the somatic tissue layers around bones were investigated. Cuff pressure was applied on the lower leg at three different stimulation intensities (mild pressure to pain). Three-dimensional finite element models including bones and three different layers of deep tissues were developed based on magnetic resonance images (MRI). The skin indentation maps at mild pressure, pain threshold, and intense painful stimulations were extracted from MRI and applied to the model. The mean stress under the cuff position around tibia was 4.6, 4.9 and around fibula 14.8, 16.4 times greater than mean stress of muscle surface in the same section at pain threshold and intense painful stimulations, respectively. At the same stimulation intensities, the mean strains around tibia were 36.4, 42.3 % and around fibula 32.9, 35.0 %, respectively, of mean strain on the muscle surface. Assuming strain as the ideal stimulus for nociceptors the results suggest that cuff algometry is less capable to challenge the nociceptors of tissues around bones as compared to more superficially located muscles.

Pressure pain sensitivity changes after use of shock-absorbing insoles among young soccer players training on artificial turf: a randomized controlled trial

STUDY DESIGN

Prospective, randomized, controlled single-blind intervention trial.

OBJECTIVES

Shock-absorbing insoles (SAIs), compared with usual insoles, were hypothesized to result in larger increases in pressure pain threshold (PPT) after 3 weeks of use.

BACKGROUND

Shock-absorbing insoles can decrease self-reported pain among young soccer players training on artificial turf. However, nothing is known about the underlying changes in pain sensitivity assessed by PPT. Methods Seventy-five players were included from the youth teams of under 15, under 17, and under 19 years of age, playing for the Aalborg Boldspilklub (AaB) professional sports club. After a randomization stratified by team and age, players were divided into 2 groups, one that received SAIs and a control group that used their usual insoles. Assessments were made in both groups after 3 weeks of training on artificial turf (baseline) and 3 weeks later (follow-up). The primary outcome was change in PPTs from baseline to follow-up, with PPTs measured over 13 locations on the plantar surface of the foot, leg, and low back of the nonpreferred kicking leg.

RESULTS

A significantly larger increase was found in PPTs from baseline to follow-up for the SAI group compared with the control group (mean difference, 62 kPa; 95% confidence interval [CI]: 40, 85 kPa). The PPTs increased significantly more among the SAI group compared with the control group (P<.05) for the abductor digiti minimi (mean difference, 82 kPa; 95% CI: 6, 157 kPa), tibialis anterior (mean difference, 125 kPa; 95% CI: 20, 230 kPa), medial gastrocnemius (mean difference, 83 kPa; 95% CI: -6, 171 kPa), and erector spinae (mean difference, 86 kPa; 95% CI: -17, 188 kPa).

CONCLUSION

The use of SAIs resulted in increased PPTs after 3 weeks of training on artificial turf compared with controls, suggesting a protective role of SAIs in pressure sensitivity and pain perception.

Randomized trial of trigger point acupuncture treatment for chronic shoulder pain: a preliminary study

There is evidence for the efficacy of acupuncture treatment for chronic shoulder pain, but it remains unclear which acupuncture modes are most effective. We compared the effect of trigger point acupuncture (TrP), with that of sham (SH) acupuncture treatments, on pain and shoulder function in patients with chronic shoulder pain. The participants were 18 patients (15 women, 3 men; aged 42-65 years) with nonradiating shoulder pain for at least 6 months and normal neurological findings. The participants were randomized into two groups, each receiving five treatment sessions. The TrP group received treatment at trigger points for the muscle, while the other group received SH acupuncture treatment on the same muscle. Outcome measures were pain intensity (visual analogue scale, VAS) and shoulder function (Constant-Murley Score: CMS). After treatment, pain intensity between pretreatment and 5 weeks after TrP decreased significantly (p<0.001). Shoulder function also increased significantly between pretreatment and 5 weeks after TrP (p<0.001). A comparison using the area under the outcome curves demonstrated a significant difference between groups (p=0.024). Compared with SH acupuncture therapy, TrP therapy appears more effective for chronic shoulder pain.

Effects of trigger point acupuncture treatment on temporomandibular disorders: a preliminary randomized clinical trial

We compared the effects of trigger point acupuncture with that of sham acupuncture treatments on pain and oral function in patients with temporomandibular disorders (TMDs). This 10-week study included 16 volunteers from an acupuncture school with complaints of chronic temporomandibular joint myofascial pain for at least 6 months. The participants were randomized to one of two groups, each receiving five acupuncture treatment sessions. The trigger point acupuncture group received treatment at trigger points for the same muscle, while the other acupuncture group received sham treatment on the trigger points. Outcome measures were pain intensity (visual analogue scale) and oral function (maximal mouth opening). After treatment, pain intensity was less in the trigger point acupuncture group than in the sham treatment group, but oral function remained unchanged in both groups. Pain intensity decreased significantly between pretreatment and 5 weeks after trigger point (p<0.001) and sham acupunctures (p<0.050). Group comparison using the area under the curve demonstrated a significant difference between groups (p=0.0152). Compared with sham acupuncture therapy, trigger point acupuncture therapy may be more effective for chronic temporomandibular joint myofascial pain.

Involvement of NGF in the rat model of persistent muscle pain associated with taut band

Myofascial pain syndrome (MPS) is an important clinical condition characterized by chronic muscle pain and a myofascial trigger point (MTrP) located in a taut band (TB). However, its pathogenic mechanism is still unclear. We developed an animal model relevant to conditions of MPS, and analyzed the mechanism of the muscle pain in this model. We applied eccentric contraction (EC) to a rat's gastrocnemius muscle (GM) for 2 weeks, and examined the mechanical withdrawal thresholds, histological changes, and expressions and contents of nerve growth factor (NGF). The mechanical withdrawal threshold decreased significantly at the next day of first EC and continued up to 9 days after EC. TBs were palpable at 3 to 8 days after initiation of EC. In EC animals, necrotic and regenerating muscle cells were found significantly more than in control animals. In EC animals, NGF expressions in regenerating muscle cells and NGF contents of GM were significantly higher than control animals. Administration of NGF receptor (TrkA) inhibitor K252a showed significant suppression of mechanical hyperalgesia in EC animals. Repeated EC induced persistent mechanical muscle hyperalgesia associated with TB. NGF expressed in regenerating muscle cells may have an important role in persistent mechanical muscle hyperalgesia which might be relevant to pathogenesis of MPS.

PERSPECTIVE

The present study shows that NGF expressed in regenerating muscle cells is involved in persistent muscular mechanical hyperalgesia. NGF-TrkA signaling in primary muscle afferent neurons may be one of the most important and promising targets for MPS.

Effect of acupuncture depth on muscle pain

Background

While evidence supports efficacy of acupuncture and/or dry needling in treating musculoskeletal pain, it is unclear which needling method is most effective. This study aims to determine the effects of depth of needle penetration on muscle pain.

Methods

A total of 22 healthy volunteers performed repeated eccentric contractions to induce muscle soreness in their extensor digital muscle. Subjects were assigned randomly to four groups, namely control group, skin group (depth of 3 mm: the extensor digital muscle), muscle group (depth of 10 mm: the extensor digital muscle) and non-segmental group (depth of 10 mm: the anterior tibial muscle). Pressure pain threshold and electrical pain threshold of the skin, fascia and muscle were measured at a point 20 mm distal to the maximum tender point on the second day after the exercise.

Results

Pressure pain thresholds of skin group (depth of 3 mm: the extensor digital muscle) and muscle group (depth of 10 mm: the extensor digital muscle) were significantly higher than the control group, whereas the electrical pain threshold at fascia of muscle group (depth of 10 mm: the extensor digital muscle) was a significantly higher than control group; however, there was no significant difference between the control and other groups.

Conclusion

The present study shows that acupuncture stimulation of muscle increases the PPT and EPT of fascia. The depth of needle penetration is important for the relief of muscle pain.

Bradykinin and nerve growth factor play pivotal roles in muscular mechanical hyperalgesia after exercise (delayed-onset muscle soreness)

Unaccustomed strenuous exercise that includes lengthening contraction (LC) often causes delayed-onset muscle soreness (DOMS), a kind of muscular mechanical hyperalgesia. The substances that induce this phenomenon are largely unknown. Peculiarly, DOMS is not perceived during and shortly after exercise, but rather is first perceived after approximately 1 d. Using B(2) bradykinin receptor antagonist HOE 140, we show here that bradykinin released during exercise plays a pivotal role in triggering the process that leads to muscular mechanical hyperalgesia. HOE 140 completely suppressed the development of muscular mechanical hyperalgesia when injected before LC, but when injected 2 d after LC failed to reverse mechanical hyperalgesia that had already developed. B(1) antagonist was ineffective, regardless of the timing of its injection. Upregulation of nerve growth factor (NGF) mRNA and protein occurred in exercised muscle over a comparable time course (12 h to 2 d after LC) for muscle mechanical hyperalgesia. Antibodies to NGF injected intramuscularly 2 d after exercise reversed muscle mechanical hyperalgesia. HOE 140 inhibited the upregulation of NGF. In contrast, shortening contraction or stretching induced neither mechanical hyperalgesia nor NGF upregulation. Bradykinin together with shortening contraction, but not bradykinin alone, reproduced lasting mechanical hyperalgesia. We also showed that rat NGF sensitized thin-fiber afferents to mechanical stimulation in the periphery after 10-20 min. Thus, NGF upregulation through activation of B(2) bradykinin receptors is essential (though not satisfactory) to mechanical hyperalgesia after exercise. The present observations explain why DOMS occurs with a delay, and why lengthening contraction but not shortening contraction induces DOMS.

Effects of tender point acupuncture on delayed onset muscle soreness (DOMS)--a pragmatic trial

Background

Acupuncture is used to reduce inflammation and decrease pain in delayed onset muscle soreness (DOMS). This study investigates the efficacy of acupuncture on the symptoms of DOMS.

Methods

Thirty subjects were assigned randomly to there groups, namely the control, non-tender point and tender point groups. Measurement of pain with full elbow flexion was used as indices of efficacy. Measurements were taken before and after exercise, immediately after treatment and seven days after treatment.

Results

Significant differences in visual analog scores for pain were found between the control group and tender point group immediately after treatment and three days after exercise (P < 0.05, Dunnetts multiple test).

Conclusion

The results show that tender point acupuncture relieves muscle pain of DOMS.

A musculoskeletal model of low grade connective tissue inflammation in patients with thyroid associated ophthalmopathy (TAO): the WOMED concept of lateral tension and its general implications in disease

Background

Low level connective tissue inflammation has been proposed to play a role in thyroid associated ophthalmopathy (TAO). The aim of this study was to investigate this postulate by a musculoskeletal approach together with biochemical parameters.

Methods

13 patients with TAO and 16 controls were examined. Erythrocyte levels of Zn, Cu, Ca²⁺, Mg, and Fe were determined. The musculoskeletal evaluation included observational data on body posture with emphasis on the orbit-head region. The angular foot position in the frontal plane was quantified following gait observation. The axial orientation of the legs and feet was evaluated in an unloaded supine position. Functional propioceptive tests based on stretch stimuli were done by using foot inversion and foot rotation.

Results

Alterations in the control group included neck tilt in 3 cases, asymmetrical foot angle during gait in 2, and a reaction to foot inversion in 5 cases. TAO patients presented facial asymmetry with displaced eye fissure inclination (mean 9.1°) as well as tilted head-on-neck position (mean 5.7°). A further asymmetry feature was external rotation of the legs and feet (mean 27°). Both foot inversion as well as foot rotation induced a condition of neuromuscular deficit. This condition could be regulated by gentle acupressure either on the lateral abdomen or the lateral ankle at the acupuncture points gall bladder 26 or bladder 62, respectively. In 5 patients, foot rotation produced a phenomenon of moving toes in the contra lateral foot. In addition foot rotation was accompanied by an audible tendon snapping. Lower erythrocyte Zn levels and altered correlations between Ca²⁺, Mg, and Fe were found in TAO.

Conclusion

This whole body observational study has revealed axial deviations and body asymmetry as well as the phenomenon of moving toes in TAO. The most common finding was an arch-like displacement of the body, i.e. eccentric position, with foot inversion and head tilt to the contra lateral side and tendon snapping. We propose that eccentric muscle action over time can be the basis for a low grade inflammatory condition. The general implications of this model and its relations to Zn and Se will be discussed.

How do acupuncture and moxibustion act? - Focusing on the progress in Japanese acupuncture research -

The mechanisms of action of acupuncture and moxibustion as reported by Japanese researchers are reviewed. The endogenous opioid-mediated mechanisms of electroacupuncture (EA) as used in China are well understood, but these are only one component of all mechanisms of acupuncture. These studies emphasize the similarity of the analgesic action of EA to various sensory inputs to the pain inhibition mechanisms. In Japanese acupuncture therapy, careful detection of the acupuncture points and fine needling technique with comfortable subjective sensation are considered important. The role of polymodal receptors (PMR) has been stressed based on the facts that PMRs are responsive to both acupuncture and moxibustion stimuli, thermal sensitivity is essential in moxibustion therapy, and the characteristics of acupuncture points and trigger points are similar to those of sensitized PMRs. Acupuncture and moxibustion are also known to affect neurons in the brain reward systems and blood flow in skin, muscle, and nerve. Axon reflexes mediated by PMRs might be a possible mechanism for the immediate action of acupuncture and moxibustion. Reports on the curative effects of acupuncture on various digestive and urological disorders are also reviewed briefly.

Effects of trigger point acupuncture on chronic low back pain in elderly patients--a sham-controlled randomised trial

INTRODUCTION

There is some evidence for the efficacy of acupuncture, but it remains unclear whether trigger point acupuncture is effective. Our objective was to evaluate the effects of trigger point acupuncture on pain and quality of life in chronic low back pain patients compared with sham acupuncture.

METHODS

Twenty-six consecutive out-patients (17 women, 9 men; age range: 65-91 years) from the Department of Orthopaedic Surgery, Meiji University of Oriental Medicine, with non-radiating low back pain for at least six months and normal neurological examination, were randomised to two groups. Each group received one phase of trigger point acupuncture and one of sham acupuncture with a three week washout period between them, over 12 weeks. Group A (n = 13) received trigger point acupuncture in the first phase and sham acupuncture in the second. Group B (n = 13) received the same interventions in the reverse order. Outcome measures were pain intensity (visual analogue scale, VAS) and Roland Morris Questionnaire.

RESULTS

Nineteen patients were included in the analysis. At the end of the first treatment phase, group A receiving trigger point acupuncture scored significantly lower VAS (P < 0.001) and Roland Morris Questionnaire scores (P < 0.01) than the sham control group. There were significant within-group reductions in pain in both groups during the trigger point acupuncture phase but not in the sham treatment phase. However, the beneficial effects were not sustained.

CONCLUSION

These results suggest that trigger point acupuncture may have greater short term effects on low back pain in elderly patients than sham acupuncture.

Randomised trial of trigger point acupuncture compared with other acupuncture for treatment of chronic neck pain

INTRODUCTION

There is some evidence for the efficacy of acupuncture in chronic neck pain (CNP) treatment, but it remains unclear which acupuncture modes are most effective. Objective was to evaluate the effects of trigger point acupuncture on pain and quality of life (QOL) in CNP patients compared to three other acupuncture treatments (acupoints, non-trigger point and sham treatment).

METHODS

Forty out-patients (29 women, 11 men; age range: 47-80 years) from the Department of Orthopaedic Surgery, Meiji University of Oriental Medicine, with non-radiating CNP for at least 6 months and normal neurological examination were randomised to one of four groups over 13 weeks. Each group received two phases of acupuncture treatment with an interval between them. The acupoint group (standard acupuncture; SA, n=10) received treatment at traditional acupoints for neck pain, the trigger point (TrP, n=10) and non-trigger point (non-TrP, n=10) groups received treatment at tenderness points for the same muscle, while the other acupuncture group received sham treatments on the trigger point (SH, n=10). Outcome measures were pain intensity (visual analogue scale; VAS 0-100mm) and disease specific questionnaire (neck disability index; NDI, 60-point scale).

RESULTS

After treatment, the TrP group reported less pain intensity and improved QOL compared to the SA or non-TrP group. There was significant reduction in pain intensity between the treatment and the interval for the TrP group (p<0.01, Dunnett's multiple test), but not for the SA or non-TrP group.

CONCLUSION

These results suggest that trigger point acupuncture therapy may be more effective on chronic neck pain in aged patients than the standard acupuncture therapy.

Delayed onset muscle soreness at tendon-bone junction and muscle tissue is associated with facilitated referred pain

Delayed onset muscle soreness (DOMS) involves central and peripheral pain mechanisms. Referred pain patterns following stimulation of DOMS affected tissue have not been fully described. Referred pain may provide information on how central mechanisms are involved in DOMS, as referred pain is a central mechanism. Further, tendon tissue involvement in DOMS is not clear. This study assessed pressure pain threshold (PPT) sensitivity at the tendon, tendon-bone junction (TBJ) and muscle belly sites of tibialis anterior pre- and during DOMS in 45 subjects (34 males, 11 females). Furthermore, pain and referred pain areas at these three sites in response to hypertonic saline injection (n = 15 per injection site) were investigated pre- and during DOMS. DOMS was induced using controlled plantarflexion from a platform (bodyweight as resistance) causing eccentric contraction of the tibialis anterior muscle. DOMS induced PPT decrease was found at the TBJ and muscle belly sites only (P < 0.001). No mechanical effect was found in the unexercised limb. Maximal pain intensity induced by hypertonic saline given pre-DOMS was significantly higher for the tendon and TBJ injections compared to intramuscular injections (P < 0.05). Significantly higher referred pain frequency and enlarged pain areas were found at the muscle belly and TBJ sites following injection during DOMS compared to pre-DOMS. The results indicate that muscle belly and TBJ sites are sensitised while tendon tissue per se is unaffected by DOMS. Central sensitivity changes caused by DOMS may explain the increase in referred pain frequency and enlarged pain areas.

Augmented mechanical response of muscle thin-fiber sensory receptors recorded from rat muscle-nerve preparations in vitro after eccentric contraction

Unaccustomed strenuous exercise, especially that from eccentric muscular work, often causes muscle tenderness, which is a kind of mechanical hyperalgesia. We developed an animal model of delayed-onset muscle soreness (DOMS) from eccentric muscular contraction (ECC) in rats and demonstrated the existence of muscle tenderness by means of behavioral pain tests and c-Fos protein expression in the spinal dorsal horn. The purpose of the present study was to examine whether the sensitivities of muscle thin-fiber sensory receptors to mechanical, chemical, and thermal stimuli were altered after repetitive ECC in a rat model of DOMS. ECC was caused in the animals by electrical stimulation of the common peroneal nerve innervating the extensor digitorum longus muscle (EDL) while the muscle was being stretched. Activities of single thin-fiber receptors (sensitive to pressure but insensitive to stretch, with conduction velocity slower than 2.0 m/s) were recorded from muscle (EDL)-nerve preparations in vitro 2 days after ECC when mechanical hyperalgesia was at its peak. The mechanical threshold of thin-fiber receptors was found to be very much lower in the ECC preparations than in the nontreated control (CTR) [median 65.4 mN (interquartile range [IQR]; 46.6-122.0 mN) in the CTR preparation vs. 38.2 mN (IQR; 26.8-55.8 mN) in the ECC, P < 0.001]. In addition, the total number of evoked discharges during a ramp mechanical stimulus, taken as an index of the magnitude of the mechanical response, nearly doubled in the ECC preparations compared with the CTR [24.7 spikes (IQR; 14.2-37.1 spikes) in the CTR preparation vs. 54.2 spikes (IQR; 24.3-89.0 spikes) in the ECC, P < 0.001]. In contrast, the numbers of discharges induced by chemical (pH 5.5, lactic acid, adenosine triphosphate, and bradykinin) and thermal (cold and heat) stimuli were not different between the two preparations. These results suggest that augmentation of the mechanical response in muscle thin-fiber sensory receptors might be related to the muscle tenderness in DOMS after ECC.

Enhanced temporal summation of pressure pain in the trapezius muscle after delayed onset muscle soreness

Temporal summation of muscle pain is an important factor in musculoskeletal pain as central integration of repetitive nociceptive input can be facilitated in musculoskeletal pain patients. The aim of this study is to evaluate changes in temporal summation of pressure pain after induction of delayed onset muscle soreness (DOMS) of the trapezius muscle. Sixteen healthy volunteers participated in the study. Temporal summation of pain was induced by sequential pressure stimulation by a computer-controlled algometer. Sequential stimulation consisting of ten stimuli (at pressure pain threshold intensity) was applied over the trapezius muscle. Stimulus duration was 1 s and inter-stimulus intervals (ISI) were 1, 5, 10, and 30 s, respectively. The pain was rated on a continuous visual analogue scale (VAS, 10 cm) after each stimulus and normalised to the VAS score from the first stimulus. DOMS was induced in the right trapezius muscle by eccentric shoulder exercises while the left trapezius muscle served as control. Temporal summation of pressure evoked pain was measured before and 24 h after the exercise. At 24 h after exercise, soreness intensity during shoulder elevation was 3.7+/-0.2 cm, while no soreness was observed on the control side. When sequential pressure stimulation was applied to the DOMS muscle, VAS scores for 1 s ISI progressively increased to a higher level than before exercise (VAS increase for the last stimulus: 0.8+/-0.2 cm vs. 0.6+/-0.1 cm, P<0.05), while VAS scores for ISI 5, 10, and 30 s were not increased. On the control side, significant increases in VAS scores was observed for all ISIs but not affected by contralateral DOMS. Facilitation of temporal summation for 1 s ISI indicated that DOMS may increase the central excitability besides involving peripheral sensitisation. During DOMS there was no potential for further nociceptor sensitisation by repeated noxious pressure stimuli, which may account for the diminishment of temporal summation evoked by pressure stimuli with ISI 5, 10, and 30 s. These data indicate that muscle soreness might facilitate the central components of temporal summation to mechanical stimulation.

Trigger point acupuncture treatment of chronic low back pain in elderly patients--a blinded RCT

OBJECTIVE

There is some evidence for the efficacy of acupuncture in chronic low back pain, but it remains unclear which acupuncture modes are most effective. Our objective was to evaluate the effects of two different modes of trigger point acupuncture on pain and quality of life in chronic low back pain patients compared to standard acupuncture treatment.

METHODS

Thirty five consecutive out-patients (25 women, 10 men; age range: 65-81 years) from the Department of Orthopaedic Surgery, Meiji University of Oriental Medicine, with non-radiating low back pain for at least six months and normal neurological examination, were randomised to one of three groups over 12 weeks. Each group received two phases of acupuncture treatment with an interval between them. Nine patients dropped out during the course of the study. The standard acupuncture group (n=9) received treatment at traditional acupuncture points for low back pain, while the other acupuncture groups received superficial (n=9) or deep (n=9) treatments on trigger points. Outcome measures were VAS pain intensity and Roland Morris Questionnaire.

RESULTS

After treatment, the group that received deep needling to trigger points reported less pain intensity and improved quality of life compared to the standard acupuncture group or the group that received superficial needling to trigger points, but the differences were not statistically significant. There was a significant reduction in pain intensity between the treatment and interval in the group that received deep needling to trigger points (P<0.01), but not in the standard acupuncture group or the group that received superficial needling to trigger points.

CONCLUSION

These results suggest that deep needling to trigger points may be more effective in the treatment of low back pain in elderly patients than either standard acupuncture therapy, or superficial needling to trigger points.

Muscular mechanical hyperalgesia revealed by behavioural pain test and c-Fos expression in the spinal dorsal horn after eccentric contraction in rats

Delayed onset muscle soreness (DOMS) is quite common, but the mechanism for this phenomenon is still not understood; even the existence of muscle tenderness (mechanical hyperalgesia) has not been demonstrated in experimental models. We developed an animal model of DOMS by inducing eccentric contraction (lengthening contraction, ECC) to the extensor digitorum longus muscle (EDL), and investigated the existence of mechanical hyperalgesia in the EDL by means of behavioural pain tests (Randall-Selitto test and von Frey hair test, applied to/through the skin on the EDL muscle) and c-Fos expression in the spinal dorsal horn. We found that the mechanical withdrawal threshold measured with the Randall-Selitto apparatus decreased significantly between 1 and 3 days after ECC, while that measured by von Frey hairs did not. The group that underwent stretching of the muscle only (SHAM group) showed no change in mechanical pain threshold in either test. These results demonstrated that the pain threshold of deep tissues (possibly of the muscle) decreased after ECC. c-Fos immunoreactivity in the dorsal horn (examined 2 days after ECC/SHAM exercise) was not changed by either ECC or compression (1568 mN) to the EDL muscle by itself, but it was significantly increased by applying compression to the EDL muscle 2 days after ECC. This increase was observed in the superficial dorsal horn of the L4 segment of the ipsilateral side, and was clearly suppressed by morphine treatment (10 mg kg(-1), i.p.). These results demonstrated the existence of mechanical hyperalgesia in the muscle subjected to ECC. This model could be used for future study of the neural mechanism of muscle soreness.

A proposed experimental model of myofascial trigger points in human muscle after slow eccentric exercise

BACKGROUND

The purpose of this study was to develop an experimental model of myofascial trigger points to investigate their pathophysiology.

METHODS

Fifteen healthy volunteers who gave informed consent underwent repetitive eccentric exercise of the third finger of one hand (0.1 Hz repetitions, three sets at five minute intervals) until exhaustion. Physical examination, pressure pain threshold, and electrical pain threshold of the skin, fascia and muscle were measured immediately afterwards and for seven days. Needle electromyogram (EMG) was also recorded in a subgroup of participants.

RESULTS

Pressure pain thresholds decreased to a minimum on the second day after the exercise, then gradually returned to baseline values by the seventh day. On the second day, a ropy band was palpated in the exercised forearm muscle and the electrical pain threshold of the fascia at the palpable band was the lowest among the measured loci and tissues. Needle EMG activity accompanied with dull pain sensation was recorded only when the electrode was located on or near the fascia of the palpable band on the second day of exercise.

CONCLUSION

These results suggest that eccentric exercise may yield a useful model for the investigation of the myofascial trigger points and/or acupuncture points. The sensitised nociceptors at the fascia of the palpable band might be a possible candidate for the localised tender region.