Muscle Injury Prevention Research Articles

Enhancing Sports Injury Risk Assessment in Soccer Through Machine Learning and Training Load Analysis.

Sports injuries pose significant challenges in athlete welfare and team dynamics, particularly in high-intensity sports like soccer. This study used machine learning algorithms to assess non-contact injury risk in professional male soccer players from physiological and mechanical load variables. Twenty-five professional male soccer players with a first-time, non-contact muscle injury were included in this study. Recordings of external load (speed, distance, and acceleration/deceleration data) and internal load (heart rate) were obtained during all training sessions and official matches over a 4-year period. Machine learning model training and evaluation features were calculated for each of nine different metrics for a 28-day period prior to the injury and an equal-length baseline epoch. The acute surge in the values of each workload metric was quantified by the deviation of maximum values from the average, while the variations of cumulative workload over the last four weeks preceding injury were also calculated. Seven features were selected by the model as prominent estimators of injury incidence. Three of the features concerned acute load deviations (number of sprints, training load score-incorporating heart rate and muscle load- and time of heart rate at the 90-100% of maximum). The four cumulative load features were (total distance, high speed and sprint running distance and training load score). The accuracy of the muscle injury risk assessment model was 0.78, with a sensitivity of 0.73 and specificity of 0.85. Our model achieved high performance in injury risk detection using a limited number of training load variables. The inclusion, for the first time, of heart rate related variables in an injury risk assessment model highlights the importance of physiological overload as a contributor to muscle injuries in soccer. By identifying the important parameters, coaches may prevent muscle injuries by controlling surges of training load during training and competition.

Research on countermeasures for safety prevention of muscle injury in sports under the background of big data and smart medicine

With the deepening of quality-oriented education and the implementation of new curriculum standards, the forms and contents of school sports activities are increasingly diversified. In this regard, special attention must be paid to sports safety. Sports is a sport to improve physical and mental health, but it is easy to cause physical injury in sports. Big data can effectively monitor the normalization of movement in the process of exercise, so as to take timely safety precautions and reduce the probability of muscle injury. Therefore, by analyzing the causes and influencing factors of muscle injury in sports, this paper puts forward some safety precautions to avoid muscle injury accidents during sports. Through the neural network algorithm, it can be seen that with the increase of time, the function width and prevention index of security are constantly rising, and the average value of function width is about 0.83. The seventh day is 0.15 higher than the first day, the average value of prevention index is 1.31, and the seventh day is 0.19 higher than the first day. The effect of the optimized safety prevention strategy is better than that of the traditional safety prevention strategy, and the probability of muscle injury of athletes is also greatly reduced by 11% compared with the traditional one; However, the rehabilitation effect has improved a lot, 9% higher than the traditional one.

Association of Genetic Profile with Muscle Mass Gain and Muscle Injury Prevention in Professional Football Players after Creatine Supplementation.

In recent years, the study of creatine supplementation in professional athletes has been of great interest. However, the genetics involved in response to supplementation is unknown. The aim of this study was to analyse, for the first time, the relationship between muscle performance-related genes and the risk of an increased body mass index (BMI) and muscle mass and a decrease in fat mass in professional football players after creatine supplementation. For this longitudinal study, one hundred and sixty-one men's professional football players were recruited. The polymorphisms ACE I/D, ACTN3 c.1729C>T, AMPD1 c.34C>T, CKM c.*800A>G, and MLCK (c.49C>T and c.37885C>A) were genotyped using Single-Nucleotide Primer Extension (SNPE). To assess the combined impact of these six polymorphisms, a total genotype score (TGS) was calculated. The creatine supplementation protocol consisted of 20 g/day of creatine monohydrate for 5 days (loading dose) and 3-5 g/day for 7 weeks (maintenance dose). Anthropometric characteristics (body mass index (BMI), fat, and muscle mass) were recorded before and after the creatine supplementation protocol. Characteristics of non-contact muscle injuries during the 2022/2023 season were classified according to a consensus statement for injury recording. The results showed that the allelic frequencies of ACE and AMPD1 differed between responders and non-responders in muscle mass increase (all p < 0.05). Players with a TGS exceeding 54.16 a.u. had an odds ratio (OR) of 2.985 (95%CI: 1.560-5.711; p = 0.001) for muscle mass increase. By contrast, those with a TGS below 54.16 a.u. had an OR of 9.385 (95%CI: 4.535-19.425; p < 0.001) for suffering non-contact muscle injuries during the season. The increase in BMI and muscle mass in response to creatine supplementation in professional football players was influenced by a TGS derived from the combination of favourable genotypes linked to muscle performance. The CC genotype and C allele of AMPD1 were particularly associated with a higher likelihood of muscle mass increase under creatine supplementation in this group of professional football players.

Maintaining mitochondrial NAD+ homeostasis is key for heat-induced skeletal muscle injury prevention despite presence of intracellular cation alterations.

Mitochondrial dysfunction is implicated in heat-induced skeletal muscle (SKM) injury and its underlying mechanisms remain unclear. Evidence suggests that cellular ions and molecules, including divalent cations and adenine nucleotides, are involved in the regulation of mitochondrial function. In this study, we examined Ca2+, Mg2+, and NAD+ levels in mouse C2C12 myoblasts and SKM in response to heat exposure. During heat exposure, mitochondrial Ca2+ levels increased significantly, whereas cytosolic Ca2+ levels remained unaltered. The mitochondrial Ca2+ levels in the SKM of heat-exposed mice were 28% higher compared to control mice. No changes in cytosolic Ca2+ were detected between the two groups. Following heat exposure, cytosolic and mitochondrial Mg2+ levels were reduced by 47% and 23% in C2C12 myoblasts, and by 51% and 44% in mouse SKMs, respectively. In addition, heat exposure decreased mitochondrial NAD+ levels by 32% and 26% in C2C12 myoblasts and mouse SKMs, respectively. Treatment with the NAD+ precursor nicotinamide riboside (NR) partially prevented heat-induced depletion of NAD+. Additionally, NR significantly reduced heat-increased mitochondrial fission, mitochondrial depolarization, and apoptosis in C2C12 myoblasts and mouse SKMs. No effects of NR on heat-induced changes in intracellular Ca2+ and Mg2+ levels were observed. This study provides in vitro and in vivo evidence that acute heat stress causes alterations in mitochondrial Ca2+, Mg2+, and NAD+ homeostasis. Our results suggest mitochondrial NAD+ homeostasis as a therapeutic target for the prevention of heat-induced SKM injury.

Stretching intervention can prevent muscle injuries: a systematic review and meta-analysis

Stretching intervention can prevent muscle injuries: a systematic review and meta-analysis

Leu promotes C2C12 cell differentiation by regulating the GSK3β/β-catenin signaling pathway through facilitating the interaction between SESN2 and RPN2.

Leucine (Leu) is an essential amino acid that facilitates skeletal muscle satellite cell differentiation, yet its mechanism remains underexplored. Sestrin2 (SESN2) serves as a Leu sensor, binding directly to Leu, while ribophorin II (RPN2) acts as a signaling factor in multiple pathways. This study aimed to elucidate Leu's impact on mouse C2C12 cell differentiation and skeletal muscle injury repair by modulating RPN2 expression through SESN2, offering a theoretical foundation for clinical skeletal muscle injury prevention and treatment. Leu addition promoted C2C12 cell differentiation compared to the control, enhancing early differentiation via myogenic determinant (MYOD) up-regulation. Sequencing revealed SESN2 binding to and interacting with RPN2. RPN2 overexpression up-regulated MYOD, myogenin and myosin heavy chain 2, concurrently decreased p-GSK3β and increased nuclear β-catenin. Conversely, RPN2 knockdown yielded opposite results. Combining RPN2 knockdown with Leu rescued increased p-GSK3β and decreased nuclear β-catenin compared to Leu absence. Hematoxylin and eosin staining results showed that Leu addition accelerated mouse muscle damage repair, up-regulating Pax7, MYOD and RPN2 in the cytoplasm, and nuclear β-catenin, confirming that the role of Leu in muscle injury repair was consistent with the results for C2C12 cells. Leu, bound with SESN2, up-regulated RPN2 expression, activated the GSK3β/β-catenin pathway, enhanced C2C12 differentiation and expedited skeletal muscle damage repair. © 2024 Society of Chemical Industry.

The knowledge of movement experts about stretching effects: Does the science reach practice?

Stretching is performed with numerous purposes in multiple settings such as prevention, rehabilitation, fitness training and sports. Its patterns of use substantially depend on the education and beliefs of health care and exercise professionals as they represent the multiplicators recommending and prescribing interventions to clients, patients and athletes. This study investigated movement experts' knowledge about the scientific evidence on stretching effects. Survey study. A total of 117 exercise and health professionals (physiotherapists, sports scientists, coaches) attending a training convention in Austria (male: n = 44, female: n = 73, 36±11 years) completed a digital survey. With its 22 items, the questionnaire addressed the movement experts' awareness of the evidence on stretching effects regarding a variety of related topics selected based on the findings of topical systematic reviews. The majority of the individuals (57-88%) assumed positive effects of stretching on recovery, prevention of muscle injury, range of motion, muscular imbalance and artery elasticity. No or adverse effects were mostly claimed on bone injury prevention, maximal/explosive strength, and delayed-onset muscle soreness. In only 10 of 22 items, participants' classifications were in accord with the scientific evidence. The awareness of research findings on stretching effects among exercise and health professionals is alarmingly low. Future studies may hence be geared to improve implementation and science communication.

Polyethylene microplastics induced inflammation via the miR-21/IRAK4/NF-κB axis resulting to endoplasmic reticulum stress and apoptosis in muscle of carp

As a widespread environmental pollutant, microplastics pose a great threat to the tissues and organs of aquatic animals. The carp's muscles are necessary for movement and survival. However, the mechanism of injury of polyethylene microplastics (PE-MPs) to carp muscle remains unclear. Therefore, in this study, PE-MPs with the diameter of 8 μm and the concentration of 1000 ng/L were used to feed carp for 21 days, and polyethylene microplastic treatment groups was established. The results showed that PE-MPs could cause structural abnormalities and disarrangement of muscle fibers, and aggravate oxidative stress in muscles. Exposure to PE-MPs reduced microRNA (miR-21) in muscle tissue, negatively regulated Interleukin-1 Receptor Associated Kinase 4 (IRAK4), activated Nuclear Factor Kappa-B (NF-κB) pathway, induced inflammation, and led to endoplasmic reticulum stress and apoptosis. The present study provides different targets for the prevention of muscle injury induced by polyethylene microplastics.

Traumatic muscle injury.

Traumatic muscle injury represents a collection of skeletal muscle pathologies caused by trauma to the muscle tissue and is defined as damage to the muscle tissue that can result in a functional deficit. Traumatic muscle injury can affect people across the lifespan and can result from high stresses and strains to skeletal muscle tissue, often due to muscle activation while the muscle is lengthening, resulting in indirect and non-contact muscle injuries (strains or ruptures), or from external impact, resulting in direct muscle injuries (contusion or laceration). At a microscopic level, muscle fibres can repair focal damage but must be completely regenerated after full myofibre necrosis. The diagnosis of muscle injury is based on patient history and physical examination. Imaging may be indicated to eliminate differential diagnoses. The management of muscle injury has changed within the past 5 years from initial rest, immobilization and (over)protection to early activation and progressive loading using an active approach. One challenge of muscle injury management is that numerous medical treatment options, such as medications and injections, are often used or proposed to try to accelerate muscle recovery despite very limited efficacy evidence. Another challenge is the prevention of muscle injury owing to the multifactorial and complex nature of this injury.

Stretchable surface electromyography electrode array patch for tendon location and muscle injury prevention

Surface electromyography (sEMG) can provide multiplexed information about muscle performance. If current sEMG electrodes are stretchable, arrayed, and able to be used multiple times, they would offer adequate high-quality data for continuous monitoring. The lack of these properties delays the widespread use of sEMG in clinics and in everyday life. Here, we address these constraints by design of an adhesive dry electrode using tannic acid, polyvinyl alcohol, and PEDOT:PSS (TPP). The TPP electrode offers superior stretchability (~200%) and adhesiveness (0.58 N/cm) compared to current electrodes, ensuring stable and long-term contact with the skin for recording (>20 dB; >5 days). In addition, we developed a metal-polymer electrode array patch (MEAP) comprising liquid metal (LM) circuits and TPP electrodes. The MEAP demonstrated better conformability than commercial arrays, resulting in higher signal-to-noise ratio and more stable recordings during muscle movements. Manufactured using scalable screen-printing, these MEAPs feature a completely stretchable material and array architecture, enabling real-time monitoring of muscle stress, fatigue, and tendon displacement. Their potential to reduce muscle and tendon injuries and enhance performance in daily exercise and professional sports holds great promise.

A review of ergogenic nutritional supplements for athletes

Ergogenic supplements are defined as substances that contribute to or support the doing or production of a job. These supplements are used for many purposes such as increasing the performance of athletes, accelerating recovery in athletes, improving capacity, and reducing and preventing muscle injuries and muscle fatigue. Ergogenic supplements, which are of great interest to athletes and trainers, are classified as nutritional aids, pharmacological aids, psychological aids, mechanical and biomechanical aids, and physiological aids. Among these supplements, they are the most actively used nutritional aids and attract attention in the market as muscle-building nutritional supplements, weight-reducing nutritional supplements, performance-enhancing nutritional supplements, and general health-promoting nutritional supplements. Protein and amino acids provide benefits in long-term or short-term explosive power activities. Fats are used as the main fuel in long-term aerobic exercises. In addition, caffeine, ginseng, antioxidants, and coenzyme Q10 also serve as ergogenic nutritional supplements. It has been reported in studies that minerals such as B, C and E vitamins, chromium, magnesium, iron, and zinc affect sports performance in a good way. In case of deficiency of the aforementioned vitamins and minerals in athletes, many negativities occur. In this study, the use of ergogenic nutritional supplements by athletes before, during, and after training was compiled using the current literature on the types of these supplements.

Combined influence of psychological and biomechanical factors in muscular loads in soccer : Anew approach for the prevention of muscle injuries

When mental stress and musculoskeletal loading interact, the risk for injury increases due to altered body kinematics and increased muscle tension. These changes can be detected with musculoskeletal models, and mental loading and stress must be analyzed at emotional, cognitive, and behavioral levels. To investigate these kinematic and loading changes under stress, competitive athletes were subjected to mental stress during highly dynamic movements, and musculoskeletal models were used to analyze the biomechanical loading. It was shown that under mental stress, independent of the subjective perception, astrong change in muscle forces can occur. Accordingly, competitive athletes should undergo screenings to assess individual movement patterns and promote general stress resilience.

Genetics in sports-muscle injuries

The human genome is the complete set of genetic instructions encoded in an individual's DNA. Genetics plays an important role in the development and progression of muscle injuries. Many genes are involved in muscle development, growth, and repair, and variations in these genes can affect an athlete's susceptibility to muscle injury. Several genes have been linked to muscle injury, such as myostatin (MSTN), insulin-like growth factor1 (IGF-1), and several collagen genes (COL). In addition to genes involved in muscle development, growth, and repair, genes involved in inflammation and pain signaling, such as tumor necrosis factor alpha (TNF-α), mu opioid receptor (OPRM1), and interleukin (IL) genes, may also play arole in the development and progression of muscle injury. Genetic testing can be ahelpful tool in the prevention of muscle injuries in athletes. Testing for variations in genes associated with muscle development, repair, and growth, as well as collagen formation, can provide valuable information about an athlete's susceptibility to muscle injury. It is important to note that while genetic testing can provide valuable information for injury prevention, it is only one piece of the puzzle. Other factors such as an individual's training history, general health, and lifestyle habits also play arole in injury risk. Therefore, all injury prevention strategies should be individualized and based on acomprehensive assessment of all relevant factors.

ASIC3 plays a protective role in delayed-onset muscle soreness (DOMS) through muscle acid sensation during exercise.

Immediate exercise-induced pain (IEIP) and DOMS are two types of exercise-induced muscle pain and can act as barriers to exercise. The burning sensation of IEIP occurs during and immediately after intensive exercise, whereas the soreness of DOMS occurs later. Acid-sensing ion channels (ASICs) within muscle afferents are activated by H+ and other chemicals and have been shown to play a role in various chronic muscle pain conditions. Here, we further defined the role of ASICs in IEIP, and also tested if ASIC3 is required for DOMS. After undergoing exhaustive treadmill exercise, exercise-induced muscle pain was assessed in wild-type (WT) and ASIC3-/- mice at baseline via muscle withdrawal threshold (MWT), immediately, and 24 h after exercise. Locomotor movement, grip strength, and repeat exercise performance were tested at baseline and 24 h after exercise to evaluate DOMS. We found that ASIC3-/- had similar baseline muscle pain, locomotor activity, grip strength, and exercise performance as WT mice. WT showed diminished MWT immediately after exercise indicating they developed IEIP, but ASIC3-/- mice did not. At 24 h after baseline exercise, both ASIC3-/- and WT had similarly lower MWT and grip strength, however, ASIC3-/- displayed significantly lower locomotor activity and repeat exercise performance at 24 h time points compared to WT. In addition, ASIC3-/- mice had higher muscle injury as measured by serum lactate dehydrogenase and creatine kinase levels at 24 h after exercise. These results show that ASIC3 is required for IEIP, but not DOMS, and in fact might play a protective role to prevent muscle injury associated with strenuous exercise.

Impact of different nutritional approaches on sarcopenia: a protocol for systematic review and network meta-analysis

Although it is known that proper nutrition is effective in managing sarcopenia, the most powerful nutrients have not yet been determined. This study is designed to investigate the effects of various nutritional approaches on muscle mass, muscle strength, and sarcopenia prevention in systematic reviews. In study design, network and pairwise meta-analyses of randomized clinical trials were considered. Clinical studies regarding the nutritional effects associated with the physiological activity of skeletal muscle and management of sarcopenia will be covered. The main outcomes will cover the following five elements: anti-fatigue impact with skeletal muscle, muscle atrophy prevention, differentiation level with skeletal muscular cell, anti-inflammatory effect, and muscle injury prevention. Authors will conduct the study selection, extracting data process, and methodological quality investigation.Systematic review registrationOSF registry (ethical approval number: https://osf.io/ye4q7).

Knee Flexor Eccentric Strength, Hamstring Muscle Volume and Sprinting in Elite Professional Soccer Players with a Prior Strained Hamstring.

Simple SummaryGiven the link between a prior hamstring injury and the increased risk of suffering a subsequent injury in professional soccer, an understanding of the features displayed by previously injured players is important. The aim of the present study was to investigate if players with a history of hamstring injury exhibit bilateral deficits in knee flexor eccentric strength, hamstring muscle volume, and sprinting performance. The eccentric knee flexor strength was greater in the previously injured limbs compared to both the contralateral uninjured limbs in the previously injured group and the uninjured limbs in the previously uninjured players. Previously injured limbs showed possibly larger short heads of the biceps femoris and likely semitendinosus muscle volumes. Sprinting performances in the 5-m were possibly worse in players with a history of hamstring muscle strain injury compared to the previously uninjured players.The aim was to determine if players with a prior hamstring strain injury (HSI) exhibit bilateral deficits in knee flexor eccentric strength and hamstring muscle volume and differences in sprinting performance compared with players without a history of HSIs. Forty-six male professional soccer players participated in this study. Eccentric knee flexor strength, hamstring muscle volume (MRI), and a 20-m running sprint test (5- and 10-m split time) were assessed at the start of the preseason. Eccentric knee strength of the previously injured limbs of injured players was greater (ES: 1.18–1.36) than the uninjured limbs in uninjured players. Previously injured limbs showed possibly larger biceps femoris short heads (BFSh) and likely semitendinosus (ST) muscle volumes than the contralateral uninjured limbs among the injured players (ES: 0.36) and the limbs of the uninjured players (ES: 0.56), respectively. Players who had experienced a previous HSI were possibly slower in the 5-m (small ES: 0.46), while unclear differences were found in both the 10-m and 20-m times. Players with a prior HSI displayed greater eccentric knee flexor strength, possibly relatively hypertrophied ST and BFSh muscles, and possibly reduced 5-m sprinting performances than previously uninjured players. This can have implication for the design of secondary hamstring muscle injury prevention strategies.

Cryostimulation for Post-exercise Recovery in Athletes: A Consensus and Position Paper.

Recovery after exercise is a crucial key in preventing muscle injuries and in speeding up the processes to return to homeostasis level. There are several ways of developing a recovery strategy with the use of different kinds of traditional and up-to-date techniques. The use of cold has traditionally been used after physical exercise for recovery purposes. In recent years, the use of whole-body cryotherapy/cryostimulation (WBC; an extreme cold stimulation lasting 1–4 min and given in a cold room at a temperature comprised from −60 to −195°C) has been tremendously increased for such purposes. However, there are controversies about the benefits that the use of this technique may provide. Therefore, the main objectives of this paper are to describe what is whole body cryotherapy/cryostimulation, review and debate the benefits that its use may provide, present practical considerations and applications, and emphasize the need of customization depending on the context, the purpose, and the subject's characteristics. This review is written by international experts from the working group on WBC from the International Institute of Refrigeration.

VITAMIN D SUPPLEMENTATION: EFFECT ON THE 25(OH)D PROFILE AND OCCURRENCE OF MUSCLE INJURIES IN PROFESSIONAL SOCCER ATHLETES

ABSTRACT Context: Vitamin D insufficiency has been described among professional soccer athletes. Objective: To evaluate 25(OH)D profile and occurrence of muscle injuries (MI) in Series A athletes with (2015 season - S1) and without Vitamin D supplementation (2016 season - S2). Methods: An observational, analytical, prospective, cohort study of 22 athletes who received the same evaluation at the start of the seasons and 25(OH)D and total calcium measurements in January and August of S1 and S2. Data on MI were obtained from the physiotherapy department of the club. Results: Chronological age: 23.4 ± 3.0 years; height (cm) 182 ± 0.7; total body mass (kg) 78.5 ± 8.6; total lean mass (kg) 65.9 ± 6.7 and total fat mass (kg) 13.2 ± 3.3. Solar radiation (kj/m2) at 10 a.m. did not differ between S1 and S2 (p = 0.19) while at 3 p.m., there was a significant difference (S2 > S1, p = 0.01). Total calcium was different between January and August of S2 (p <0.001); in August, the 25(OH)D of S2 was significantly lower than that of S1 in January (p = 0.01). On August of S2, 78.9% of the athletes had 25(OH)D values within the range of insufficiency/deficiency (p = 0.02). MI were twice as frequent in S2 (31 vs 16); the midfield and forward athletes were the ones most affected; grade I injuries were more prevalent; in S1, MI were more frequent in the dominant limb (75.0%) while in S2, there was no difference between the dominant (35.5%) and non-dominant (48.4%) limbs. Conclusion: Professional soccer athletes with adequate exposure to solar radiation do not appear to benefit from vitamin D supplementation to prevent muscle injuries. Level of evidence II, Therapeutic study.

A Comparative Evaluation of Effectiveness of InGaAsP Laser and Therapeutic Ultrasound Administration Before the Induction of Muscle Fatigue on Healthy Young Individuals

Background: Muscle fatigue or the inability to maintain muscle strength is a protective mechanism to prevent muscle injury. Phototherapy or low-level laser therapy (LLLT) and therapeutic ultrasound are non-invasive and non-pharmacological forms of treatment modalities that have demonstrated effective and affirmative results when used to prevent muscle fatigue. Aim: The study evaluated the effect of phototherapy and therapeutic ultrasound in reducing muscle fatigue when administered before the induction of fatigue. Methodology: The study design was a blind, randomized, and sham-controlled clinical trial on laser and therapeutic ultrasound. The study sample consisted of 100 healthy young participants randomly allocated to four different groups of lasers, sham laser, therapeutic ultrasound, and sham ultrasound. All the individuals were subjected to clinical examination to record the bite force by the bite force dynamometer, maximum interincisal distance (MID) by using digital vernier calipers, and muscle fatigue by using EMG Retrainer's Device. The laser and therapeutic ultrasound were given on the masseter and anterior temporalis muscle on both sides and both sham groups were submitted to the same procedure but with the devices in the switch-off mode. All the individuals were instructed to chew two pieces of gum (one on each side) for 6 min to induce muscle fatigue and MID, the bite force and muscle fatigue were re-evaluated. Results: Statistically significant improvement was observed between the pre-and post-bite force, MID, and muscle fatigue in both the laser and Therapeutic ultrasound group as compared to the sham control groups with the P-value equal to 0.000. No, statistically significant difference was observed in the improvement of the muscle fatigue when both the treatment groups, i.e., laser and therapeutic ultrasound were compared with a P value &gt;0.05. Conclusion: Muscle fatigue can be effectively reduced if any one of the physical modalities, either laser or therapeutic ultrasound is administered before the long-duration treatments; enabling administration of treatment comfortably and effectively in one appointment.

Oral administration of angiotensin-(1-7) decreases muscle damage and prevents the fibrosis in rats after eccentric exercise.

What is the central question of this study? Eccentric contraction exercises cause damage to muscle fibres and induce inflammatory responses. The exacerbation of this process can induce deposition of fibrous connective tissue, leading to decreased muscle function. The aim of this study was to examine the role of angiotensin-(1-7) in this context. What is the main finding and its importance? Our results show that oral treatment with angiotensin-(1-7) decreases muscle damage induced by eccentric exercise, reducing inflammation and fibrosis in the gastrocnemius and soleus muscles. This study shows a potential effect of angiotensin-(1-7) for the prevention of muscle injuries induced by physical exercise. Eccentric contraction exercises cause damage to the muscle fibres and induce an inflammatory reaction. The protective effect of angiotensin-(1-7) [Ang-(1-7)] in skeletal muscle has led us to examine the role of this peptide in modifying processes associated with inflammation and fibrogenesis induced by eccentric exercise. In this study, we sought to investigate the effects of oral administration of Ang-(1-7) formulated in hydroxypropyl β-cyclodextrin (HPβ-CD) in prevention and treatment of muscle damage after downhill running. Male Wistar rats were divided into three groups: control (untreated and not exercised; n=10); treated/exercised HPβ-CD Ang-(1-7) (n=40); and treated/exercised HPβ-CD (n=40). Exercised groups were subjected to a single eccentric contraction exercise session on a treadmill inclined to -13° at a constant speed of 20m/min, for 60min. Oral administration of HPβ-CD Ang-(1-7) and HPβ-CD was performed 3 h before the exercise protocol and daily as a single dose, until the end of the experiment. Samples were collected 4, 12, 24, 48 and 72h after the exercise session. The animals treated with the Ang-(1-7) showed lower levels of creatine kinase, lower levels of tumor necrosis factor-α in soleus muscle and increased levels of interleukin-10 cytokines. The inflammatory cells and deposition of fibrous connective tissue in soleus and gastrocnemius muscles were lower in the group treated with Ang-(1-7). The results of this study show that treatment with an oral formulation of Ang-(1-7) enhances the process of repair of muscle injury induced by eccentric exercise.