Rehabilitation of muscle after injury - the role of anti-inflammatory drugs

The dose-response effects of flurbiprofen, indomethacin, ibuprofen, and naproxen on primary skeletal muscle cells

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, flurbiprofen, naproxen sodium, and indomethacin are commonly employed for their pain-relieving and inflammation-reducing qualities. NSAIDs work by blocking COX-1 and/or COX-2, enzymes which play roles in inflammation, fever, and pain. The main difference among NSAIDs lies in their affinity to these enzymes, which in turn, influences prostaglandin secretion, and skeletal muscle growth and regeneration. The current study investigated the effects of NSAIDs on human skeletal muscle cells, focusing on myoblast proliferation, differentiation, and muscle protein synthesis signaling.

METHODS

Using human primary muscle cells, we examined the dose-response impact of flurbiprofen (25-200 µM), indomethacin (25-200 µM), ibuprofen (25-200 µM), and naproxen sodium (25-200 µM), on myoblast viability, myotube area, fusion, and prostaglandin production.

RESULTS

We found that supraphysiological concentrations of indomethacin inhibited myoblast proliferation (-74 ± 2% with 200 µM; -53 ± 3% with 100 µM; both p < 0.05) compared to control cells and impaired protein synthesis signaling pathways in myotubes, but only attenuated myotube fusion at the highest concentrations (-18 ± 2% with 200 µM, p < 0.05) compared to control myotubes. On the other hand, ibuprofen had no such effects. Naproxen sodium only increased cell proliferation at low concentrations (+36 ± 2% with 25 µM, p < 0.05), and flurbiprofen exhibited divergent impacts depending on the concentration whereby low concentrations improved cell proliferation (+17 ± 1% with 25 µM, p < 0.05) but high concentrations inhibited cell proliferation (-32 ± 1% with 200 µM, p < 0.05).

CONCLUSION

Our findings suggest that indomethacin, at high concentrations, may detrimentally affect myoblast proliferation and differentiation via an AKT-dependent mechanism, and thus provide new understanding of NSAIDs' effects on skeletal muscle cell development.

Development of a local controlled release system for therapeutic proteins in the treatment of skeletal muscle injuries and diseases

The present study aims to develop and characterize a controlled-release delivery system for protein therapeutics in skeletal muscle regeneration following an acute injury. The therapeutic protein, a membrane-GPI anchored protein called Cripto, was immobilized in an injectable hydrogel delivery vehicle for local administration and sustained release. The hydrogel was made of poly(ethylene glycol)-fibrinogen (PEG-Fibrinogen, PF), in the form of injectable microspheres. The PF microspheres exhibited a spherical morphology with an average diameter of approximately 100 micrometers, and the Cripto protein was uniformly entrapped within them. The release rate of Cripto from the PF microspheres was controlled by tuning the crosslinking density of the hydrogel, which was varied by changing the concentration of poly(ethylene glycol) diacrylate (PEG-DA) crosslinker. In vitro experiments confirmed a sustained-release profile of Cripto from the PF microspheres for up to 27 days. The released Cripto was biologically active and promoted the in vitro proliferation of mouse myoblasts. The therapeutic effect of PF-mediated delivery of Cripto in vivo was tested in a cardiotoxin (CTX)-induced muscle injury model in mice. The Cripto caused an increase in the in vivo expression of the myogenic markers Pax7, the differentiation makers eMHC and Desmin, higher numbers of centro-nucleated myofibers and greater areas of regenerated muscle tissue. Collectively, these results establish the PF microspheres as a potential delivery system for the localized, sustained release of therapeutic proteins toward the accelerated repair of damaged muscle tissue following acute injuries.

Non-steroidal anti-inflammatory drugs in football - a "Keeping SCORE" approach to judicious use

Non-steroidal anti-inflammatory drug (NSAID) use in elite sport is high, with football being no exception. Increased awareness of significant adverse drug reactions from published research and retired players commentary in the media have made the topic mainstream. Despite this increased awareness, usage rates show no sign of significantly reducing. Footballers, like all elite athletes are focused on maximising their performance and potential - even at the expense of their long-term health. An educational intervention prior to the 2010 FIFA Men's World Cup aimed at reducing rates was ineffective, suggesting that education alone is not the answer. Our author group propose a 'safer use' rather than 'no use' of NSAIDs in football. A 'Keeping SCORE' approach is suggested, designed as a prescribing aid. The approach guides medical staff towards focusing on Safety checks, Clinical indication/judgement, Open dialogue, Recording, and Evaluation.

Effectiveness of cryo plus ultrasound therapy versus diathermy in combination with high-intensity laser therapy for pain relief in footballers with muscle injuries: A prospective study

BACKGROUND

Muscle injuries are common traumatic events in the clinical practice of the rehabilitation field. There is still a gap in the scientific literature on the effectiveness of physical agent modalities in the management of muscle injuries in athletes.

OBJECTIVE

The aim of this study was to assess the effectiveness of cryo plus ultrasound therapy com-pared to diathermy in combination with high-intensity laser therapy (HILT) for pain relief in professional footballers with muscle injuries.

METHODS

A case-control study was conducted on 31 professional footballers with a muscle injury of the lower limbs. Of these, 17 patients, assigned to a Group A (AG), were treated with HILT and cryoultrasound therapy; the remaining 14 patients, assigned to a Group B (BG), underwent HILT and diathermy. We assessed the extent of the pain, the size of the muscle injury, frequency of recurrence and number of days to recovery, at the time of recruitment, at the end of the rehabilitation and 3 months after the injury.

RESULTS

Group A athletes had a greater benefit on pain (4.65 ± 0.61 vs 3.24 ± 0.63; p< 0.05) and muscle injury recurrence. The return to play in the athletes of group A took place 4.73 days earlier.

CONCLUSION

HILT and cryo plus ultrasound therapy, in combination with therapeutic exercise, rep-resent a valid strategy in the treatment of muscle injuries in professional footballers.

Sodium salicylate ameliorates exercise-induced muscle damage in mice by inhibiting NF-kB signaling

BACKGROUND

Eccentric muscle contraction can cause muscle damage, which reduces the efficiency of exercise. Previous evidence suggested that Sodium salicylate (SS) could improve the repair of aged muscle. This study intends to investigate whether SS can impact skeletal muscle damage caused by eccentric exercise.

METHODS

Eccentric treadmill exercise was performed to induce muscle damage in mice. Plasma levels of muscle damage markers were estimated. RT-qPCR was employed for detecting mRNA levels of proinflammatory mediators in murine gastrocnemius muscle. Immunofluorescence staining of laminin/DAPI was utilized for quantifying centrally nucleated myofibers in the gastrocnemius muscle. Western blotting was implemented to examine protein levels of mitsugumin 53 (MG53), matrix metalloproteinase (MMP)-2/9, and NF-κB signaling-related markers.

RESULTS

SS administration reduced muscle damage marker production in the plasma and decreased the levels of proinflammatory mediators, MG53 and MMP-2/9 in mice after exercise. SS alleviated the severity of muscle damage in the gastrocnemius of mice after eccentric exercise. SS blocked NF-κB signaling pathway in the gastrocnemius muscle.

CONCLUSION

SS administration ameliorates skeletal muscle damage caused by eccentric exercise in the mouse model.

Efficacy of topical versus oral analgesic medication compared to a placebo in injured athletes: A systematic review with meta-analysis

BACKGROUND

Athletes are injured frequently and often take analgesic medication. Moreover, athletes commonly use non-prescription topical and oral medications with little guidance. Despite wide use, relatively few studies exist on the efficacy of pain medication in injured athletes compared to a placebo.

OBJECTIVE

To determine efficacy of topical or oral medications in pain reduction compared to a placebo in injured athletes.

STUDY DESIGN

A systematic review and meta-analysis.

METHODS

We conducted an electronic search using Medline/Pubmed, Web of Science, Ovid, and SportDiscus for all literature relating to topical or oral medications in athletes for pain management post-injury. Two reviewers screened the studies and measured their quality. To determine efficacy, we calculated the Hedges' g value. We created forest plots with 95% CI to graphically summarize the meta-analyses.

RESULTS

There was a significant pooled effect size reflecting a reduction in pain outcomes for the topical treatment versus placebo (g = -0.64; 95% CI [-0.89, -0.39]; p < 0.001). There was not a significant reduction in pain outcomes for the oral treatment versus placebo (g = -0.26; 95% CI [-0.60, 0.17]; p = 0.272).

CONCLUSION

Topical medications were significantly better at reducing pain compared to oral medications versus a placebo in injured athletes. These results are different when compared to other studies that used experimentally induced pain versus musculoskeletal injuries. The results from our study suggest that athletes should use topical medications for pain reduction, as it is more effective, and there are less reported adverse effects compared to oral medication.

Is Injury an Occupational Hazard for Horseracing Staff?

Occupational health is a key priority for the horseracing industry, yet little research on occupational injuries exists. This study investigated the prevalence and the effect of injury in British horseracing staff during a 12-month period. An online retrospective survey was answered by 352 participants, identifying self-reported injury prevalence, injury management practices and attitudes towards workplace injury reporting. Chi Squared tests for independence were undertaken. A total of 310 (88.1%) staff reported injuries; risk factors for injury type included self-perceived job security, working hours, and perceived job control. Physical limitations, loss of confidence, workplace changes, and lifestyle implications were reported as consequences of injury. A total of 75.3% (n = 134) of staff were likely to seek time-off following fractures, but only 48.6% (n = 86) would take time-off for concussion. Attitudes towards injury management were influenced by financial circumstances, perceived staff shortages, previous injury experiences, and perceived employer expectations. The high self-reported injury prevalence could result in decreased workforce efficiency, poor physical health, and negative implications on retention and career longevity. The perception of invisible injuries, i.e., concussion, and subsequent management, should be of immediate concern to racing organizations. This paper identifies recommendations to enhance the safety and wellbeing of horseracing staff.

Muscle function and architecture in children with juvenile idiopathic arthritis

AIM

To assess muscle function and functional abilities in children with juvenile idiopathic arthritis (JIA).

METHODS

Fourteen children with JIA and 14 healthy controls matched for age and sex were included. Muscle characteristics, both structural (thickness, cross-sectional area (CSA) and fascicle angle) and qualitative (intermuscular adipose tissue; IMAT), were assessed in thigh muscles using ultrasound and peripheral quantitative computed tomography (pQCT). Muscle function and functional abilities were determined from the assessment of maximal voluntary isometric contraction (MVIC) knee extensors force and vertical jump performance.

RESULTS

No significant difference in MVIC force was observed between the two groups. However, squat jump height was significantly reduced in children with JIA (18.3 ± 5.4 vs 24.3 ± 7.9 cm, P < .05). No differences in structural parameters were observed, but IMAT/CSA (0.22 ± 0.02 vs 0.25 ± 0.03; P = .01) was significantly lower in children with JIA than in healthy children.

CONCLUSION

Knee extensor muscle architecture and force were comparable between children with and without JIA, but functional abilities (vertical jump performance) were poorer in JIA. The lower IMAT area in JIA could result from a lower physical activity level compared with healthy children.

Ibuprofen does not impair skeletal muscle regeneration upon cardiotoxin-induced injury

Muscle regeneration is regulated through interaction between muscle and immune cells. Studies showed that treatment with supra-physiological doses of Non-Steroidal Anti-Inflammatory Drug (NSAID) abolished inflammatory signaling and impaired muscle recovery. The present study examines the effects of pharmacologically-relevant NSAID treatment on muscle regeneration. C57BL/6 mice were injected in the tibialis anterior (TA) with either PBS or cardiotoxin (CTX). CTX-injected mice received ibuprofen (CTX-IBU) or were untreated (CTX-PLAC). After 2 days, Il-1beta and Il-6 expression was upregulated in the TA of CTX-IBU and CTX-PL vs. PBS. However, Cox-2 expression and macrophage infiltration were higher in CTX-PL vs. PBS, but not in CTX-IBU. At the same time, anabolic markers were higher in CTX-IBU vs. PBS, but not in CTX-PL. Nevertheless, ibuprofen did not affect muscle mass or muscle fiber regeneration. In conclusion, mild ibuprofen doses did not worsen muscle regeneration. There were even signs of a transient improvement in anabolic signaling and attenuation of inflammatory signaling.

Curcumin and Nanocurcumin Oral Supplementation Improve Muscle Healing in a Rat Model of Surgical Muscle Laceration

OBJECTIVE

To compare the effects of curcumin and nanocurcumin oral supplementation on the muscle healing rate of an animal model of surgical muscle laceration.

METHODS

Thirty-two male adult rats were randomly divided into sham, control, curcumin, and nanocurcumin groups. Partial transection of the gastrocnemius muscle was made in the right limb of the control and treatment groups. The sham and control groups received normal saline, curcumin group received 500 mg/kg of curcumin and nanocurcumin group received 100 mg curcumin-loaded nanomicelles orally every day. They euthanized two weeks later and the specimens were stained by hematoxylin-eosin (H&E) and Masson's trichrome methods. Aspartate transaminase (AST) and creatine phosphokinase (CPK) were measured in blood samples.

RESULTS

The percentage of collagen fibers in the nanocurcumin group was significantly lesser than the control and curcumin groups (p<0.001). Muscle fiber regeneration in the treatment groups was significantly higher than the control group (p<0.001). The blood vessels of the nanocurcumin group were significantly more than other groups (p<0.001). Plasma AST had a significant difference in the control group compared to the sham and nanocurcumin groups (p=0.026). The plasma CPK level of the control group was also significantly higher than other groups (p<0.001).

CONCLUSION

In conclusion, although oral curcumin supplementation has little effects because of its poor bioavailability, embedding it in nanoparticles could enhance its systemic effects in promoting the muscle healing process.

Winning at all costs: a review of risk-taking behaviour and sporting injury from an occupational safety and health perspective

Professional athletes involved in high-performance sport are at a high injury risk, which may lead to long-term health consequences. Professional athletes often expose themselves to risky behaviours, resulting in a higher acceptance level of occupational risk compared to other occupations. To date, many studies have focused on elite athletes' specific injury prevention techniques. The objective of this narrative review is to (1) summarise elite athletes' attitudes towards important occupational safety and health (OSH) practices, including injury reporting, medicine usage and personal protective equipment (PPE) usage, and (2) explore factors that may influence elite athletes' injury awareness. If injury awareness were given a similar weighting in elite sports as in any other highly physical occupation, the potential benefits to elite athletes and their long-term health could be highly significant. This review identifies that most elite athletes are not aware that sporting injuries are occupational injuries requiring behaviours determined by OSH rules. All the 39 studies identified met the moderate methodological quality criteria according to the Mixed Methods Appraisal Tool (MMAT). The factors impeding athletes' injury awareness from achieving occupational health standards are discussed from three safety management perspectives: organisational, societal and individual. This review contributes to a better understanding of how to build a positive safety culture, one that could reduce elite athletes' injury rate and improve their long-term wellbeing. Further research is required to develop a quantitative measurement instrument to evaluate occupational health awareness in the sport context. Based on the papers reviewed, the study population was categorised as elite, professional, high-performance amateur and student-athletes.

Winning at all costs: a review of risk-taking behaviour and sporting injury from an occupational safety and health perspective

Professional athletes involved in high-performance sport are at a high injury risk, which may lead to long-term health consequences. Professional athletes often expose themselves to risky behaviours, resulting in a higher acceptance level of occupational risk compared to other occupations. To date, many studies have focused on elite athletes' specific injury prevention techniques. The objective of this narrative review is to (1) summarise elite athletes' attitudes towards important occupational safety and health (OSH) practices, including injury reporting, medicine usage and personal protective equipment (PPE) usage, and (2) explore factors that may influence elite athletes' injury awareness. If injury awareness were given a similar weighting in elite sports as in any other highly physical occupation, the potential benefits to elite athletes and their long-term health could be highly significant. This review identifies that most elite athletes are not aware that sporting injuries are occupational injuries requiring behaviours determined by OSH rules. All the 39 studies identified met the moderate methodological quality criteria according to the Mixed Methods Appraisal Tool (MMAT). The factors impeding athletes' injury awareness from achieving occupational health standards are discussed from three safety management perspectives: organisational, societal and individual. This review contributes to a better understanding of how to build a positive safety culture, one that could reduce elite athletes' injury rate and improve their long-term wellbeing. Further research is required to develop a quantitative measurement instrument to evaluate occupational health awareness in the sport context. Based on the papers reviewed, the study population was categorised as elite, professional, high-performance amateur and student-athletes.

Effects of Perioperative Nonsteroidal Anti-inflammatory Drug Administration on Soft Tissue Healing: A Systematic Review of Clinical Outcomes After Sports Medicine Orthopaedic Surgery Procedures

Background:

The effects of perioperative nonsteroidal anti-inflammatory drugs (NSAIDs) on soft tissue healing in humans have yet to be established.

Purpose:

To systematically review the literature addressing the effects of perioperative NSAID administration on soft tissue healing and clinical patient outcomes.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

This review study was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. A review of the literature regarding the existing evidence for clinical effects of NSAID use on soft tissue healing was performed through use of the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed (1980 to present), and MEDLINE. Inclusion criteria for articles were as follows: outcome studies after soft tissue (ligament, meniscus, tendon, muscle) healing after surgical procedure with perioperative NSAID administration, at least 1 year of follow-up, English language, and human participants.

Results:

A total of 466 studies were initially retrieved, with 4 studies satisfying all inclusion criteria. Among the surgical procedures reported, 93% of the patients (4144/4451) underwent anterior cruciate ligament (ACL) reconstruction, 3% (120/4451) underwent rotator cuff repair, 3% (155/4451) underwent Bankart shoulder repair, and 1% (32/4451) underwent meniscal repair. The reported surgical failure rate among patients administered NSAIDs was 3.6% (157/4360). The reported surgical failure rate among control participants not given NSAIDs was 3.7% (147/3996). NSAID use showed no statistically significant effect on need for reoperation in meniscal repair (P = .99), ACL reconstruction (P = .8), and Bankart repair (P = .8) compared with no NSAID administration. Celecoxib administration had a significantly higher rate of retear (37%) after rotator cuff repair compared with ibuprofen (7%) (P = .009).

Conclusion:

Insufficient data are available to definitively state the effects of perioperative NSAIDs on soft tissue healing. Use of NSAIDs should be considered on a case-by-case basis and may not affect healing rates following either meniscal, ACL, rotator cuff, or Bankart repair. However, celecoxib (a selective COX-2 inhibitor) may inhibit tendon-to-bone healing in rotator cuff repair. Further research through clinical trials is required to fully determine whether NSAIDs have an adverse effect on soft tissue healing.

Analgesic and anti-inflammatory drugs in sports: Implications for exercise performance and training adaptations

Over-the-counter analgesics, such as anti-inflammatory drugs (NSAIDs) and paracetamol, are widely consumed by athletes worldwide to increase pain tolerance, or dampen pain and reduce inflammation from injuries. Given that these drugs also can modulate tissue protein turnover, it is important to scrutinize the implications of acute and chronic use of these drugs in relation to exercise performance and the development of long-term training adaptations. In this review, we aim to provide an overview of the studies investigating the effects of analgesic drugs on exercise performance and training adaptations relevant for athletic development. There is emerging evidence that paracetamol might acutely improve important endurance parameters as well as aspects of neuromuscular performance, possibly through increased pain tolerance. Both NSAIDs and paracetamol have been demonstrated to inhibit cyclooxygenase (COX) activity, which might explain the reduced anabolic response to acute exercise bouts. Consistent with this, NSAIDs have been reported to interfere with muscle hypertrophy and strength gains in response to chronic resistance training in young individuals. Although it remains to be established whether any of these observations also translate into detriments in sport-specific performance or reduced training adaptations in elite athletes, the extensive use of these drugs certainly raises practical, ethical, and important safety concerns that need to be addressed. Overall, we encourage greater awareness among athletes, coaches, and support staff on the potential adverse effects of these drugs. A risk-benefit analysis and professional guidance are strongly advised before the athlete considers analgesic medicine for training or competition.

Impact of intramuscular administration of lipid-soluble and water-soluble vehicles into regenerating muscle at the distinct phases of skeletal muscle regeneration

Interpretation on the effectiveness of potential substances to enhance skeletal muscle regeneration is difficult if an inappropriate vehicle is administered, since vehicle administration can directly enhance or suppress regenerative capacity. In the current study, intramuscular administration of lipid-soluble and water-soluble vehicles into regenerating muscle at the distinct phases of skeletal muscle regeneration (regenerative vs. remodeling) were investigated. Tested vehicles included lipid-soluble [olive oil, (0.1, 1, 5, and 40%) dimethyl sulfoxide (DMSO), and 40% propylene glycol (PG)] and water-soluble [0.9% NaCl, PBS, 0.1% ethanol, and distilled water]. Skeletal muscle regeneration was induced by 1.2% BaCl2 injection to the tibialis anterior muscle of 10-week-old C57BL/6 male mice. Histological features, skeletal muscle stem cell activity, regenerating muscle fiber formation, angiogenesis, extracellular matrix remodeling, and macrophage infiltration were examined. The results revealed repeated administration of 40% DMSO and 40% PG causes significant recurrent muscle injury, which is pronounced during the remodeling phase compared to the regenerative phase. These findings were supported by (1) massive infiltration of F4/80+ macrophages; (2) significant increase of skeletal muscle stem cell re-activation and nascent regenerating muscle fiber formation; (3) excess fibrous formation; and (4) decreased regenerating muscle fiber cross-sectional area. These deleterious effects were comparable to 2% trypsin (degenerative substance) administration and less pronounced with a single administration. Nevertheless, recurrent muscle injury was still presented with 5% DMSO administration but it can be alleviated when 0.1% DMSO was administered during the remodeling phase. In contrast, none of the tested vehicles enhanced regenerative capacity compared with IGF-1 administration. Altogether, intramuscular administration of vehicle containing high concentration of DMSO or PG could impair skeletal muscle regenerative capacity and potentially affect validation of the investigational substance.

Current status of myopathies affecting athletic horses

Muscular disorders rank among the most prevalent problems of horses competing in a broad variety of athletic disciplines, including track racing, dressage, endurance racing and Western riding disciplines. As described in this review, active scientific investigation is continuing to elucidate the different mechanisms underlying specific muscular disorders in horses, and is discovering and defining new disorders, and new methods of diagnosis, treatment and management. The flourishing field of equine rehabilitation and regenerative medicine is also driving the progressive application of a variety of modalities to the treatment and management of musculoskeletal conditions in horses. However, it is essential that this be accompanied by appropriate scientific investigation to verify the efficacy of recommended modalities and treatment protocols.

Effects of delayed NSAID administration after experimental eccentric contraction injury - A cellular and proteomics study

BACKGROUND

Acute muscle injuries are exceedingly common and non-steroidal anti-inflammatory drugs (NSAIDs) are widely consumed to reduce the associated inflammation, swelling and pain that peak 1-2 days post-injury. While prophylactic use or early administration of NSAIDs has been shown to delay muscle regeneration and contribute to loss of muscle strength after healing, little is known about the effects of delayed NSAID use. Further, NSAID use following non-penetrating injury has been associated with increased risk and severity of infection, including that due to group A streptococcus, though the mechanisms remain to be elucidated. The present study investigated the effects of delayed NSAID administration on muscle repair and sought mechanisms supporting an injury/NSAID/infection axis.

METHODS

A murine model of eccentric contraction (EC)-induced injury of the tibialis anterior muscle was used to profile the cellular and molecular changes induced by ketorolac tromethamine administered 47 hr post injury.

RESULTS

NSAID administration inhibited several important muscle regeneration processes and down-regulated multiple cytoprotective proteins known to inhibit the intrinsic pathway of programmed cell death. These activities were associated with increased caspase activity in injured muscles but were independent of any NSAID effect on macrophage influx or phenotype switching.

CONCLUSIONS

These findings provide new molecular evidence supporting the notion that NSAIDs have a direct negative influence on muscle repair after acute strain injury in mice and thus add to renewed concern about the safety and benefits of NSAIDS in both children and adults, in those with progressive loss of muscle mass such as the elderly or patients with cancer or AIDS, and those at risk of secondary infection after trauma or surgery.

Regeneration of Skeletal Muscle After Eccentric Injury

Eccentric-contraction-induced skeletal muscle injuries, included in what is clinically referred to as muscle strains, are among the most common injuries treated in the sports medicine setting. Although patients with mild injuries often fully recover to their preinjury levels, patients who suffer moderate or severe injuries can have a persistent weakness and loss of function that is refractory to rehabilitation exercises and currently available therapeutic interventions. The objectives of this review were to describe the fundamental biophysics of force transmission in muscle and the mechanism of muscle-strain injuries, as well as the cellular and molecular processes that underlie the repair and regeneration of injured muscle tissue. The review also summarizes how commonly used therapeutic modalities affect muscle regeneration and opportunities to further improve our treatment of skeletal muscle strain injuries.

Injury and illness in aquatic sport: how high is the risk? A comparison of results from three FINA World Championships

BACKGROUND

Epidemiological information on injury/illness is required to develop effective injury prevention strategies.

AIM

To assess the frequency and characteristics of injuries/illnesses (1) in the 4 weeks prior to and (2) during the Fédération Internationale de Natation (FINA) World Championships 2015 compared with 2013 and 2009.

METHOD

(1) Athletes answered a retrospective questionnaire, and (2) the medical staff reported injuries/illnesses prospectively during the championships.

RESULTS

(1) A quarter of responding athletes reported symptoms in the 4 weeks prior to the championships. More than half of all affected athletes presented with substantial severity, 80% took medication, 70% had overuse injuries and 30% did not modify their training regime despite symptoms. At the start of the championships, 70% of affected participants were still symptomatic. (2) During the championships, injury and illness incidence was 12.9 per 100 athletes. The most common injuries were shoulder sprains (5.7%) and muscle cramps of the lower back (5.7%). The most common illnesses were infections of the respiratory (33.9%) and gastrointestinal tract (23.5%). Risk factors included discipline and age, but not gender. Incidence was highest in athletes competing in high diving (HD), water polo (WP) and diving (DIV) for injuries, and WP and swimming (SW) for illnesses. The significantly higher incidence of injuries and illnesses at the FINA World Championships 2015 compared with 2013 and 2009 was most probably due to a similarly improved response rate of the medical staff.

CONCLUSIONS

In aquatic sports, surveillance and health promotion should focus on prevention of out-of-competition overuse injuries and athlete education.

Spanish Consensus Statement: The Treatment of Muscle Tears in Sport

On the 21st of March, 2015, experts met at Clínica CEMTRO in Madrid, Spain, under the patronage of The Spanish Society for Sports Traumatology (SETRADE), The Spanish Federation of Sports Medicine (FEMEDE), The Spanish Association of Medical Services for Football Clubs (AEMEF), and The Spanish Association of Medical Services for Basketball Clubs (AEMB) with the aim of establishing a round table that would allow specialists to consider the most appropriate current general actions to be taken when treating muscle tears in sport, based on proven scientific data described in the medical literature. Each expert received a questionnaire prior to the aforementioned meeting comprising a set of questions concerning therapeutic indications generally applied in the different stages present during muscle repair. The present Consensus Document is the result of the answers to the questionnaire and resulting discussion and consensus over which are the best current indications in the treatment of muscle tears in sport. Avoiding immobilization, not taking nonsteroidal anti-inflammatory drugs (NSAIDs) randomly, fostering early mobilization, increasing vascularization of injured, site and regulating inflammatory mechanisms—without inhibiting these from the early stages of the recovery period—all stood out as main points of the Consensus Document. Additionally, there is controversy concerning cell stimulation techniques and the use of growth factors or cell inhibitors. The decision concerning discharge was unanimous, as was the criteria considered when it came to performing sport techniques without pain.

Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication

With this study we investigated the role of nonsteroidal anti-inflammatory drugs (NSAIDs) in human skeletal muscle regeneration. Young men ingested NSAID [1200 mg/d ibuprofen (IBU)] or placebo (PLA) daily for 2 wk before and 4 wk after an electrical stimulation-induced injury to the leg extensor muscles of one leg. Muscle biopsies were collected from the vastus lateralis muscles before and after stimulation (2.5 h and 2, 7, and 30 d) and were assessed for satellite cells and regeneration by immunohistochemistry and real-time RT-PCR, and we also measured telomere length. After injury, and compared with PLA, IBU was found to augment the proportion of ActiveNotch1(+) satellite cells at 2 d [IBU, 29 ± 3% vs. PLA, 19 ± 2% (means ± sem)], satellite cell content at 7 d [IBU, 0.16 ± 0.01 vs. PLA, 0.12 ± 0.01 (Pax7(+) cells/fiber)], and to expedite muscle repair at 30 d. The PLA group displayed a greater proportion of embryonic myosin(+) fibers and a residual ∼2-fold increase in mRNA levels of matrix proteins (all P < 0.05). Endomysial collagen was also elevated with PLA at 30 d. Minimum telomere length shortening was not observed. In conclusion, ingestion of NSAID has a potentiating effect on Notch activation of satellite cells and muscle remodeling during large-scale regeneration of injured human skeletal muscle.-Mackey, A. L., Rasmussen, L. K., Kadi, F., Schjerling, P., Helmark, I. C., Ponsot, E., Aagaard, P., Durigan, J. L. Q., Kjaer, M. Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication.

High prevalence of medication use in professional football tournaments including the World Cups between 2002 and 2014: a narrative review with a focus on NSAIDs

The use of medication in international football has been monitored since the 2002 FIFA World Cup. Team physicians were asked to provide information on prescribed medication 72 h prior to each match for every player. 69% of adult male players reported using medication, with more than half the players using non-steroidal anti-inflammatory drugs (NSAIDs). Up to one-third of all players used NSAIDs prior to every match, regardless of whether they took the field or not. The mean intake of medication was significantly higher during the FIFA Women's World Cup (0.85 vs 0.77 substances per player and per match in men, p<0.001), whereas the use of NSAIDs was similar to that for men. In the Under-20 and Under-17 male competitions, the use of medication was lower as 60% of players used some kind of medication and 43% of the players used NSAIDs during the tournaments. Despite the potential side effects of medication, especially of NSAIDs in the recovery process after a sports activity, there is no evidence of decreasing intake. The reported incidence is alarming, and moreover is most probably underestimated, since self-medication by the players or treatment already prescribed by club physicians is not included in the published reports. Future studies should focus on the daily dosage, time of treatment and especially the medical indication for painkilling agents to better understand the underlying factors.

Inflammation during skeletal muscle regeneration and tissue remodeling: application to exercise-induced muscle damage management

Increase in the practice of sport by more and more numerous people in the Western countries is associated with an increase in muscle injuries, and in demand for improving muscle function and acceleration of muscle recovery after damage. Most of the treatments used target inflammation. Indeed, several lines of experimental evidence in animal models that are supported by human studies identify inflammatory cells, and particularly macrophages, as essential players in skeletal muscle regeneration. Macrophages act not only through their immune functions, but also control myogenesis and extracellular matrix remodeling by directly acting on myogenic precursors and fibro-adipogenic precursors. In light of these recent biological advances, the question of early treatment aiming at blunting inflammation after exercise-induced muscle injury is discussed.

Tendinopathy: Update on Pathophysiology

Synopsis Tendinopathy has become the accepted term to describe a spectrum of changes that occur in damaged and/or diseased tendons. Over the past 2 decades, there have been new insights into tendon pathophysiology of relevance to clinicians, including (1) better characterization of the overuse injury process and the resultant structural and functional disruption in chronically painful tendons, (2) improved understanding of the pathomechanics associated with chronic tendon injury, and (3) greater knowledge about the influence of lifestyle factors and drugs on tendon pathology. The implications of these new insights are discussed. J Orthop Sports Phys Ther 2015;45(11):833-841. Epub 21 Sep 2015. doi:10.2519/jospt.2015.5884.

Use and abuse of medication during 2014 FIFA World Cup Brazil: a retrospective survey

OBJECTIVE

To examine the use of medication of top-level male players during the 2014 FIFA World Cup Brazil.

DESIGN

Retrospective survey.

PARTICIPANTS/INFORMATION

736 top level players.

SETTING

The teams' physicians disclosed a list of the medications used by each player within 72 h before each match of the 2014 FIFA World Cup Brazil.

OUTCOME MEASURES

Average number of medications used per player per match or during the tournament; average number and percentage of players using at least one medication per match or during the tournament.

RESULTS

67.0% of all players took various types of medication during the tournament. The most used medications during the tournament were non-steroidal anti-inflammatory drugs (NSAIDs), by 54.2% of all players, followed by analgaesics (12.6%); β-2 agonists were only used by 0.5%. On average, 0.8 medications per player were used before each match. More players were reported taking medications during the knockout round than during the qualification round (0.36±0.48 vs 0.49±0.50, p<0.001). Players from the South American and Asian Confederations took twice as many medications per match as players from the African Confederation (1.17±1.55 and 1.01±1.26 vs 0.48±0.69, both p<0.001).

CONCLUSIONS

There was high use of NSAIDs during the 2014 FIFA World Cup. Although the intake of NSAIDs per match (0.35±0.46 vs 0.31±0.48, p<0.01) in the 2014 FIFA World Cup decreased compared to the 2010 FIFA World Cup, the average use was still higher than in the 2006 FIFA World Cup, and the average number of all used medications per player remained the same level as 4 years prior, with all its implications for the player's health. More efforts need to be undertaken worldwide in order to reduce the administration of medications in sports, through continuous education for players, starting from a young age, as well as for doctors and paramedics.

Myositis ossificans of the quadriceps femoris in a soccer player

A young soccer player was diagnosed with myositis ossificans 6 weeks after a muscle strain in the right thigh. Radiographic and sonographic investigations initially helped to confirm diagnosis and later supported clinical improvement. We present our approach to the case and discuss pathophysiology, prevention and treatment of this rare condition.

Effects of low-level laser therapy on skeletal muscle repair: a systematic review

A review of the literature was performed to demonstrate the most current applicability of low-level laser therapy (LLLT) for the treatment of skeletal muscle injuries, addressing different lasers, irradiation parameters, and treatment results in animal models. Searches were performed in the PubMed/MEDLINE, SCOPUS, and SPIE Digital Library databases for studies published from January 2006 to August 2013 on the use of LLLT for the repair of skeletal muscle in any animal model. All selected articles were critically appraised by two independent raters. Seventeen of the 36 original articles on LLLT and muscle injuries met the inclusion criteria and were critically evaluated. The main effects of LLLT were a reduction in the inflammatory process, the modulation of growth factors and myogenic regulatory factors, and increased angiogenesis. The studies analyzed demonstrate the positive effects of LLLT on the muscle repair process, which are dependent on irradiation and treatment parameters. The findings suggest that LLLT is an excellent therapeutic resource for the treatment of skeletal muscle injuries in the short-term.

Therapeutic approaches to skeletal muscle repair and healing

Context:

Skeletal muscle is comprised of a highly organized network of cells, neurovascular structures, and connective tissue. Muscle injury is typically followed by a well-orchestrated healing response that consists of the following phases: inflammation, regeneration, and fibrosis. This review presents the mechanisms of action and evidence supporting the effectiveness of various traditional and novel therapies at each phase of the skeletal muscle healing process.

Evidence Acquisition:

Relevant published articles were identified using MEDLINE (1978-2013).

Study Design:

Clinical review.

Level of Evidence:

Level 3.

Results:

To facilitate muscle healing, surgical techniques involving direct suture repair, as well as the implantation of innovative biologic scaffolds, have been developed. Nonsteroidal anti-inflammatory drugs may be potentially supplanted by nitric oxide and curcumin in modulating the inflammatory pathway. Studies in muscle regeneration have identified stem cells, myogenic factors, and β-agonists capable of enhancing the regenerative capabilities of injured tissue. Furthermore, transforming growth factor-β1 (TGF-β1) and, more recently, myostatin and the rennin-angiotensin system have been implicated in fibrous tissue formation; several antifibrotic agents have demonstrated the ability to disrupt these systems.

Conclusion:

Effective repair of skeletal muscle after severe injury is unlikely to be achieved with a single intervention. For full functional recovery of muscle there is a need to control inflammation, stimulate regeneration, and limit fibrosis.

Strength-of-Recommendation Taxonomy (SORT):

B

Acute effects of gastrocnemius muscle stretching after contusion in rats

The aim of this study was to evaluate the acute effects of stretching after gastrocnemius contusion in rats. Thirty-three male Wistar rats were selected (8 weeks, 219±35 g) and divided into 4 groups: Control (CG, n=3) - intact; Lesion (LG, n=10); Stretching (SG, n=10): Lesion and Stretching (LSG, n=10). The right gastrocnemius (RG) was submitted to contusion. Stretching on RG was performed manually, with 4 repetitions of 30 seconds each day, for 5 consecutive days, beginning 72 hour after contusion. One week later, rats were weighed and both paws were removed for investigation of muscle length, serial sarcomere number and sarcomere length. The final body weight increased in all groups. The muscle weight and length, as well as the serial sarcomere number (SSN) of LG, were higher than SG. However, the SSN of LSG was higher than SG. The sarcomere length of SG was the highest among all groups. It was concluded that the contusion and stretching did not affect body weight gain. The stretching induced sarcomerogenesis in injured muscle, but did not modify the healthy muscle.

Chronic alcohol ingestion delays skeletal muscle regeneration following injury

Background

Chronic alcohol ingestion may cause severe biochemical and pathophysiological derangements to skeletal muscle. Unfortunately, these alcohol-induced events may also prime skeletal muscle for worsened, delayed, or possibly incomplete repair following acute injury. As alcoholics may be at increased risk for skeletal muscle injury, our goals were to identify the effects of chronic alcohol ingestion on components of skeletal muscle regeneration. To accomplish this, age- and gender-matched C57Bl/6 mice were provided normal drinking water or water that contained 20% alcohol (v/v) for 18–20 wk. Subgroups of mice were injected with a 1.2% barium chloride (BaCl₂) solution into the tibialis anterior (TA) muscle to initiate degeneration and regeneration processes. Body weights and voluntary wheel running distances were recorded during the course of recovery. Muscles were harvested at 2, 7 or 14 days post-injection and assessed for markers of inflammation and oxidant stress, fiber cross-sectional areas, levels of growth and fibrotic factors, and fibrosis.

Results

Body weights of injured, alcohol-fed mice were reduced during the first week of recovery. These mice also ran significantly shorter distances over the two weeks following injury compared to uninjured, alcoholics. Injured TA muscles from alcohol-fed mice had increased TNFα and IL6 gene levels compared to controls 2 days after injury. Total protein oxidant stress and alterations to glutathione homeostasis were also evident at 7 and 14 days after injury. Ciliary neurotrophic factor (CNTF) induction was delayed in injured muscles from alcohol-fed mice which may explain, in part, why fiber cross-sectional area failed to normalize 14 days following injury. Gene levels of TGFβ₁ were induced early following injury before normalizing in muscle from alcohol-fed mice compared to controls. However, TGFβ₁ protein content was consistently elevated in injured muscle regardless of diet. Fibrosis was increased in injured, muscle from alcohol-fed mice at 7 and 14 days of recovery compared to injured controls.

Conclusions

Chronic alcohol ingestion appears to delay the normal regenerative response following significant skeletal muscle injury. This is evidenced by reduced cross-sectional areas of regenerated fibers, increased fibrosis, and altered temporal expression of well-described growth and fibrotic factors.

Monocyte/macrophage interactions with myogenic precursor cells during skeletal muscle regeneration

Adult skeletal muscle has the remarkable property of regenerating after damage, owing to satellite cells and myogenic precursor cells becoming committed to adult myogenesis to rebuild the muscle. This process is accompanied by the continuing presence of macrophages, from the phagocytosis of damaged myofibres to the full re-formation of new myofibres. In recent years, there has been huge progress in our understanding of the roles of macrophages during skeletal muscle regeneration, notably concerning their effects on myogenic precursor cells. Here, we review the most recent knowledge acquired on monocyte entry into damaged muscle, the various macrophage subpopulations, and their respective roles during the sequential phases of muscle repair. We also discuss the role of macrophages after exercise-induced muscle damage, notably in humans.