The present study compared the evolution of strength and muscle mass in swimmers of both sexes across different chronological and biological ages. Seventy-six swimmers (55 males and 21 females) from 10 to 20 years of age underwent evaluations of sexual maturation using the developmental stage of the genitals (G1, G2, G3 G4 and G5) and pubic hair (P1, P2, P3, P4 and P5) (Tanner criteria), lean mass using the dual-energy X-ray absorptiometry method, and isokinetic strength of the knee extensor muscles. Boys did not present a significant difference in strength among G1, G2, and G3 (p > 0.05) nor between 10 and 13 years of age (p > 0.05), although significant differences in strength of the extensor (p = 0.038) muscles of the knee were found between G3 and G4 and between athletes of 10 and 14 years of age (extensor muscles, p = 0.033). Muscle mass was different between G3 and G4 (p = 0.003) and between 10 and 14 years of age (p = 0.020). The mean age of boys in the G4 pubertal stage was 13.7 ± 2.0 years, although from 12 to 16 years of age, boys are typically in the G4 stage. Girls showed no significant differences in strength nor muscle mass among the pubertal stages (p > 0.05). We conclude that by equating boys by chronological age, individuals with different pubertal development levels, muscle mass, and strength levels can be grouped. Therefore, the relationship between the level of pubertal deve-lopment and chronological age seems to be a useful strategy for grouping boys, while grouping girls by chronological age seems adequate for training and competition.
Funding Acknowledgements Type of funding sources: None. Introduction Black athletes may be more likely to have uncommon electrocardiogram findings than white athletes. The prevalence of abnormal electrocardiographic findings in elite Brazilian football players (EBFP) of different ethnicities is unknown. Purpose To compare the prevalence of these changes and their correlation with the echocardiogram and cardiac magnetic resonance (CMR) in Caucasian, Mixed-race (MR), and Afro-Brazilian (AB) EBFP. Methods A multicenter cross-sectional descriptive study was conducted with exams performed on EBFP as a pre-participation assessment from February 18, 2002, through October 20, 2022. Results 4,363 EBFP from 51 professional clubs (from all five regions of Brazil; 15 states, and 21 cities), aged 15-35 years (median: 19 years; IQR: 16-23) were evaluated. 2,027 were Caucasians, 1,324 were MRs, and 1,012 were ABs. T-wave inversion (TWI) in leads II and aVF (4.2% vs. 2.3%), V5 (4.0% vs. 1.7%), and in V5-V6 (3.0% vs. 1.4%) was more common in AB than in Caucasian players, respectively (P = 0.002 for all comparisons). In addition, AB demonstrated a significantly greater prevalence of inferolateral TWI (2.3%) than Caucasian (1.1%), and MR (1.3%) EBFP, respectively. TWI in leads V1-V3 in Caucasians or MRs >16 years was present in 0.9% (30/3,351). PR interval ≥400 ms was observed in one Caucasian and in one AB athlete. The Wolff-Parkinson-White pattern was identified in two Caucasians, and a suggestive case of a type 2 Brugada Pattern in one Caucasian. Overall, 208 (4.8%) EBFP had electrocardiographic changes considered to be abnormal (4.5% in Caucasians, 4.8% in MRs, and 5.2% in ABs). Of these, 150/208 (72.1%) underwent an echocardiogram. Isolated inferior TWI was not associated with echocardiographic abnormalities (n = 25), similar to persistent juvenile TWI patterns (in Caucasians or MRs). However, TWI in inferolateral leads was associated with 10.5% echocardiographic abnormalities (4/38). Of these, 75% (3/4) had abnormal CMR findings: one AB with hypertrophic cardiomyopathy (CMP), and two Caucasians with non-compaction CMP; one Caucasian with an abnormal echocardiogram demonstrated normal CMR, suggesting "athlete's heart". Finally, one AB had normal echocardiogram results, but the CRM showed a finding compatible with apical hypertrophic CMP. Conclusion In this large cohort of EBFP, approximately 5% of the electrocardiographic findings were considered abnormal. In those with inferolateral TWI, the use of CMR may indicate the presence of potentially malignant cardiac disease, even with normal echocardiographic findings. AB ethnicity was associated with a higher prevalence of TWI in the inferior and/or lateral leads in comparison to Caucasian or MR ethnicities.
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