Browsing by Author "Lira, Claudio A.B. de"
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- Comparison of knee muscular strength balance among pre- and post-puberty adolescent swimmers: a cross-sectional pilot studyPublication . Amado, Bruno Lombardi; Lira, Claudio A.B. de; Vancini, Rodrigo Luiz; Forte, Pedro; Costa, Taline; Weiss, Katja; Knechtle, Beat; Andrade, Marilia SantosMuscular weakness and strength imbalance between the thigh muscles are considered risk factors for knee injuries. Hormonal changes, characteristic of puberty, strongly affect muscle strength; however, it is unknown whether they affect muscular strength balance. The present study aimed to compare knee flexor strength, knee extensor strength, and strength balance ratio, called the conventional ratio (CR), between prepubertal and postpubertal swimmers of both sexes. A total of 56 boys and 22 girls aged between 10 and 20 years participated in the study. Peak torque, CR, and body composition were measured using an isokinetic dynamometer and dual-energy X-ray absorptiometry, respectively. The postpubertal boys group presented significantly higher fat-free mass (p < 0.001) and lower fat mass (p = 0.001) than the prepubertal group. There were no significant differences among the female swimmers. Peak torque for both flexor and extensor muscles was significantly greater in postpubertal male (p < 0.001, both) and female swimmers (p < 0.001 and p = 0.001, respectively) than in prepubertal swimmers. The CR did not differ between the pre- and postpubertal groups. However, the mean CR values were lower than the literature recommendations, which brings attention to a higher risk of knee injuries.
- Physiological features of olympic-distance amateur triathletes, as well as their associations with performance in women and men: a cross-sectional studyPublication . Barbosa, José Geraldo; Lira, Claudio A.B. de; Vancini, Rodrigo Luiz; Anjos, Vinicius R. dos; Vivan, Lavinia; Seffrin, Aldo; Forte, Pedro; Weiss, Katja; Knechtle, Beat; Andrade, Marilia SantosThe purpose of this study was to verify the physiological and anthropometric determinants of triathlon performance in female and male athletes. This study included 40 triathletes (20 male and 20 female). Dual-energy X-ray absorptiometry (DEXA) was used to assess body composition, and an incremental cardiopulmonary test was used to assess physiological variables. A questionnaire about physical training habits was also completed by the athletes. Athletes competed in the Olympic-distance triathlon race. For the female group, the total race time can be predicted by V?O(2)max (beta = -131, t = -6.61, p < 0.001), lean mass (beta = -61.4, t = -2.66, p = 0.018), and triathlon experience (beta = -886.1, t = -3.01, p = 0.009) (r(2) = 0.825, p < 0.05). For the male group, the total race time can be predicted by maximal aerobic speed (beta = -294.1, t = -2.89, p = 0.010) and percentage of body fat (beta = 53.6, t = 2.20, p = 0.042) (r(2) = 0.578, p < 0.05). The variables that can predict the performance of men are not the same as those that can predict the triathlon performance of women. These data can help athletes and coaches develop performance-enhancing strategies.
- The fastest 24-hour ultramarathoners are from Eastern EuropePublication . Knechtle, Beat; Valero, David; Villiger, Elias; Scheer, Volker; Weiss, Katja; Forte, Pedro; Thuany, Mabliny; Vancini, Rodrigo Luiz; Lira, Claudio A.B. de; Nikolaidis, Pantelis Theo; Ouerghi, Nejmeddine; Rosemann, ThomasUltramarathon running is of increasing popularity, where the time-limited 24-hour run is one of the most popular events. Although we have a high scientific knowledge about different topics for this specific race format, we do not know where the best 24-hour runners originate from and where the fastest races are held. The purpose of the present study was to investigate the origin of these runners and the fastest race locations. A machine learning model based on the XG Boost algorithm was built to predict running speed based on the athlete´s age, gender, country of origin and the country where the race takes place. Model explainability tools were used to investigate how each independent variable would influence the predicted running speed. A sample of 171,358 race records from 63,514 unique runners from 73 countries participating in 24-hour races held in 57 countries between 1807 and 2022 was analyzed. Most of the athletes originated from the USA, France, Germany, Great Britain, Italy, Japan, Russia, Australia, Austria, and Canada. Tunisian athletes achieved the fastest average running speed, followed by runners from Russia, Latvia, Lithuania, Island, Croatia, Slovenia, and Israel. Regarding the country of the event, the ranking looks quite similar to the participation by the athlete, suggesting a high correlation between the country of origin and the country of the event. The fastest 24-hour races are recorded in Israel, Romania, Korea, the Netherlands, Russia, and Taiwan. On average, men were 0.4 km/h faster than women, and the fastest runners belonged to age groups 35–39, 40–44, and 45–49 years. In summary, the 24-hour race format is spread over the world, and the fastest athletes mainly originate from Eastern Europe, while the fastest races were organized in European and Asian countries.