Background: Musculoskeletal injuries (MSK-I) are a serious problem in sports medicine. Modifiable and non-modifiable factors are associated with susceptibility to these injuries. Thus, the aim of this study was to describe the prevalence of and identify the factors associated with MSK-I, including tendinopathy and joint and muscle injuries, in athletes.Methods: In this cross-sectional observational study, 627 athletes from rugby (n = 225), soccer (n = 172), combat sports (n = 86), handball (n = 82) and water polo (n = 62) were recruited at different sports training centres and competitions. Athlete profiles and the prevalence of MSK-I were assessed using a self-reported questionnaire. Only previous MSK-I with imaging confirmation and/or a positive physical exam by a specialized orthopaedist were considered. The association of the epidemiological, clinical and sports profiles of athletes with MSK-I was evaluated by a logistic regression model.Results: The mean age was 25 ± 6 years, and 60% of the athletes were male. The epidemiological, clinical and sports profiles of the athletes were different for the five sport groups. The MSK-I prevalence among all athletes was 76%, with 55% of MSK-I occurring in a joint, 48% occurring in a muscle and 30% being tendinopathy, and 19% of athletes had three investigated injuries. The MSK-I prevalence and injury locations were significantly different among sport groups. There was a predominance of joint injury in combat sports athletes (77%), muscle injury in handball athletes (67%) and tendinopathy in water polo athletes (52%). Age (≥30 years) was positively associated with joint (OR = 5.2 and 95% CI = 2.6–10.7) and muscle (OR = 4.9 and 95% CI = 2.4–10.1) injuries and tendinopathy (OR = 4.1 and 95% CI = 1.9–9.3).Conclusion: There is a high prevalence of tendinopathy and joint and muscle injuries among rugby, soccer, combat sports, handball and water polo athletes. The analysis of associated factors (epidemiological, clinical and sports profiles) and the presence of MSK-I in athletes suggests an approximately 4–5-fold increased risk for athletes ≥30 years of age. The identification of modifiable and non-modifiable factors can contribute to implementing surveillance programmes for MSK-I prevention.

Tendinopathy pathogenesis is associated with inflammation. Regulatory T (Treg) cells contribute to early tissue repair through an anti-inflammatory action, with the forkhead box P3 (FOXP3) transcription factor being essential for Treg function, and the FC-receptor-like 3 (FCRL3) possibly negatively regulating Treg function. FCRL3 –169T>C and FOXP3 –2383C>T polymorphisms are located near elements that regulate respective genes expression, thus it was deemed relevant to evaluate these polymorphisms as risk factors for tendinopathy development in athletes. This case-control study included 271 volleyball athletes (146 tendinopathy cases and 125 controls) recruited from the Brazilian Volleyball Federation. Genotyping analyses were performed using TaqMan assays, and the association of the polymorphisms with tendinopathy evaluated by multivariate logistic regression. Tendinopathy frequency was 63% patellar, 22% rotator cuff and 15% Achilles tendons respectively. Tendinopathy was more common in men (OR = 2.87; 95% CI = 1.67–4.93). Higher age (OR = 8.75; 95% CI = 4.33–17.69) and more years of volleyball practice (OR = 8.38; 95% CI = 3.56–19.73) were risk factors for tendinopathy. The FCRL3 –169T>C frequency was significantly different between cases and controls. After adjustment for potential confounding factors, the FCRL3 –169C polymorphism was associated with increased tendinopathy risk (OR = 1.44; 95% CI = 1.02–2.04), either considering athletes playing with tendon pain (OR = 1.98; 95% CI = 1.30–3.01) or unable to train due to pain (OR = 1.89; 95% CI = 1.01–3.53). The combined variant genotypes, FCRL3 –169TC or –169CC and FOXP3 –2383CT or –2383TT, were associated with an increased risk of tendinopathy among athletes with tendon pain (OR = 2.24; 95% CI: 1.14–4.40 and OR = 2.60; 95% CI: 1.11–6.10). The combined analysis of FCRL3 –169T>C and FOXP3 –2383C>T suggests a gene-gene interaction in the susceptibility to tendinopathy. FCRL3 –169C allele may increase the risk of developing tendinopathy, and together with knowledge of potential risk factors (age, gender and years playing) could be used to personalize elite athletes’ training or treatment in combination with other approaches, with the aim of minimizing pathology development risk.

Traumatic muscle injuries (TMIs) and muscle pain (MP) negatively impact athletes’ performance and quality of life. Both conditions have a complex pathophysiology involving the interplay between genetic and environmental factors. Yet, the existing data are scarce and controversial. To provide more insights, this study aimed to investigate the association of single-nucleotide polymorphisms (SNPs) previously linked to athletic status with TMI and MP after exercise among Brazilian high-performance athletes from different sports modalities (N = 345). The impact of important environmental determinants was also assessed. From the six evaluated SNPs (ACTN3 rs1815739, FAAH rs324420, PPARGC1A rs8192678, ADRB2 rs1042713, NOS3 rs1799983, and VDR rs731236), none was significantly associated with TMI. Regarding MP after exercise, ACTN3 rs1815739 (CC/CT vs. TT; adjusted odds ratio (aOR) = 1.90; 95% confidence interval (95%Cl), 1.01–3.57) and FAAH rs324420 (AA vs. AC/CC; aOR = 2.30; 95%Cl, 1.08–4.91) were independent predictors according to multivariate binomial analyses adjusted for age (≥23 vs. <23 years), sex (male vs. female), and tobacco consumption (yes vs. no). External validation is warranted to assess the predictive value of ACTN3 rs1815739 and FAAH rs324420. This could have implications for prophylactic interventions to improve athletes’ quality of life.

The aim of the study was to investigate whether genetic variants in VEGF and KDR genes can be correlated with susceptibility of tendinopathy in volleyball athletes. This study was conducted at the Brazilian Volleyball Federation, and comprised 179 volleyball athletes: 88 had a confirmed diagnosis of tendinopathy (cases), whereas 91 had no evidence of the disease (controls). The VEGF (-2578C>A, -460T>C and +936C>T) and KDR (-604C>T, 1192G>A and 1719T>A) polymorphisms were determined by TaqMan real-time polymerase chain reaction. The odds ratio (OR) with their 95% confidence intervals (CI) were calculated using an unconditional logistic regression model. The evaluation of demographic and clinical characteristics revealed the athlete age (P < 0.001), years of practice in volleyball (P < 0.001) and presence of pain (P = 0.001) were risk factors for tendinopathy. KDR 1192 GA and GA + AA genotypes were associated with lower risk of tendinopathy (OR: 0.41, 95% CI: 0.19–0.88 and OR: 0.47, 95% CI: 0.23–0.98, respectively). The KDR (-604C>T, 1192G>A and 1719T>A) haplotypes CGA and CAT were associated with decreased tendinopathy risk (OR: 0.46, 95% CI: 0.21–0.99 and OR: 0.23, 95% CI: 0.07–0.76, respectively). With regards to pain, traumatic lesion and away from training due to injury, VEGF and KDR polymorphisms were not associated with clinical symptoms complaints. The present results provide evidence that the KDR polymorphisms were associated with development of tendinopathy, and can contribute to identify new therapeutic targets or personalized training programs to avoid tendinopathy development in athletes.

Resumo: Objetivo Avaliar a influência de polimorfismos nos genes que codificam o colágeno tipo I e a suscetibilidade genética da tendinopatia. Metodologia Estudo caso-controle envolvendo 242 atletas brasileiros de diferentes modalidades esportivas (55 casos de tendinopatia e 187 controles). Os polimorfismos COL1A1 (rs1107946) e COL1A2 (rs412777, rs42524 e rs2621215) foram analisados pelo sistema TaqMan. As razões de chance (OR) com seus intervalos de confiança (IC) de 95% foram calculadas usando um modelo de regressão logística não-condicional. Resultados A média de idade foi de 24,0 ± 5,6 anos e 65,3% eram homens. Dos 55 casos de tendinopatia, 25,4% apresentaram mais de um tendão acometido, sendo os mais frequentes o patelar (56,3%), o manguito rotador (30,9%) e o do cotovelo ou flexores das mãos (30,9%). A idade e o tempo de prática esportiva foram associados a uma maior chance de apresentar tendinopatia (5 e 8 vezes, respectivamente). A frequência dos alelos variantes nos controles e casos, respectivamente, foi: COL1A1 rs1107946 24,0 e 29,6%; COL1A2 rs412777 36,1 e 27,8%; rs42524 17,5 e 25,9%; e rs2621215 21,3 e 27,8%. Após ajuste pelos fatores de confundimento (idade e anos de práticas esportiva), os polimorfismos COL1A2 rs42524 e rs2621215 foram associados a um risco aumentado de tendinopatia (OR = 5,5; IC95% = 1,2–24,6 e OR = 3,9; IC95% = 1,1–13,5, respectivamente). O haplótipo COL1A2 CGT foi associado a um baixo risco para desenvolvimento da doença (OR = 0,5; IC95% = 0,3–0,9). Conclusão A idade (≥ 25 anos), o tempo de prática esportiva (≥ 6 anos) e polimorfismos no gene COL1A2 aumentaram o risco de desenvolvimento da tendinopatia.

Background/Objectives: Tendon structure is predominantly composed of the extracellular matrix (ECM), and genetic variants in non-collagenous ECM components may influence susceptibility to tendinopathy. We investigated the potential influence of single nucleotide polymorphisms (SNPs) in fibrillin-2 (FBN2), tenascin-C (TNC), and matrix metalloproteinase-3 (MMP3) on the tendon regeneration failure phenotype and impact on the susceptibility to tendinopathy in Brazilian high-performance athletes. Methods: This case–control study was conducted with 397 high-performance athletes from different sports modalities (197 tendinopathy cases and 200 controls), and they were analyzed by validated TaqMan^TM SNP genotyping assays of the SNPs FBN2 (rs331079), TNC (rs2104772), and MMP3 (rs591058). Results: Out of the 197 tendinopathy cases, 63% suffered from chronic tendon pain and 22% experienced more than three episodes of disease manifestation. The TNC-rs2104772-A allele was significantly associated with tendinopathy (OR: 1.4; 95% CI: 1.1–1.8), while athletes carrying the MMP3-rs591058-T allele were linked to an increased risk of more episodes of disease manifestation (OR: 1.7; 95% CI: 1.1–2.8). The TNC-MMP3 tendon regeneration failure phenotype (TNC-A/MMP3-T) was associated with an increased risk of tendinopathy (OR: 1.4; 95% CI: 1.1–2.0) and episodes of disease manifestation (OR: 2.0; 95% CI: 1.2–3.5). Athletes with tendinopathy who had the TNC-A/MMP3-T interaction were more prone to experiencing more than three disease exacerbations (OR: 4.3; 95% CI: 1.8–10.5) compared to TNC-A/TNC-C. Conclusions: This study suggests that rs2104772 and rs591058 SNPs could be involved in the tendon regeneration failure phenotype and may influence the molecular mechanism related to the regulation of the tendon ECM during training workload.