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São Paulo, São Paulo, Brazil
Professor da EEFE-USP; Praticante e Pesquisador de Judô; Preparador físico de atletas de modalidades esportivas de combate.

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quinta-feira, 31 de março de 2011

Perda de peso e humor em atletas de luta olímpica

J Strength Cond Res. 2011 Apr;25(4):1010-5.


Effects of self-selected mass loss on performance and mood in collegiate wrestlers.
Marttinen RH, Judelson DA, Wiersma LD, Coburn JW.
Department of Kinesiology, California State University, Fullerton, California.

Abstract
Marttinen, RHJ, Judelson, DA, Wiersma, LD, and Coburn, JW. Effects of self-selected mass loss on performance and mood in collegiate wrestlers. J Strength Cond Res 25(4): 1010-1015, 2011-Wrestlers abruptly lose body mass before competition; however, the effects of "weight cutting" are poorly understood because of conflicting evidence. This study aimed to determine the effects of self-selected mass loss on precompetition mood, grip strength, and lower body power in collegiate wrestlers. Sixteen male collegiate wrestlers (age = 20 ± 2 years, height = 177.5 ± 7.2 cm) were weighed 10 days before (D-10) a competitive meet. Euhydrated subjects were administered the Brunel Mood Scale (BRUMS), tested on grip strength, and given a 30-second Wingate Anaerobic Power test to determine lower body power. Additional weigh-ins were conducted 6 (D-6) and 2 (D-2) days before competition. Subjects repeated the testing battery the day of competition (D-0). During the study, wrestlers self-selected the method and timing of mass loss. Wrestlers lost 0.0-8.1% of their body mass using exercise, caloric restriction, or fluid deprivation. Most mass loss occurred between D-2 and D-0 (mean ± SD, D-10 = 81.7 ± 18.2 kg, D-6 = 81.2 ± 17.8 kg, D-2 = 81.1 ± 18.5 kg, D-0 = 79.0 ± 19.2 kg). Wrestlers losing ≥4% body mass became significantly more confused (D-10 = 0 ± 0, D-0 = 3 ± 3); subjects losing less mass showed no difference in confusion. No significant differences existed across time for remaining BRUMS variables, grip strength, and Wingate variables. These results suggest that wrestlers self-select large, rapid mass loss that impairs aspects of psychological functioning without affecting grip strength or lower-body power.

quarta-feira, 30 de março de 2011

Impactos na cabeça em decorrência de diferentes chutes de TKD

Br J Sports Med. 2011 Apr;45(4):318-9.

Effects of olympic style taekwondo kicks on an instrumented head-form and resultant head injury measures.
Fife G, Pieter W, O'sullivan D, Cook D, Kaminski T.

Abstract
Background In taekwondo (TKD), concussion incidence is four times greater than in American football. Biomechanical investigations on concussion in TKD is sparse. Objective To examine differences in TKD kicks on resultant head linear acceleration (RLA), head injury criterion (HIC15) and peak head velocity (HVEL). Design Between-groups. Setting Biomechanics laboratory. Participants 12 elite male TKD athletes (22.5+3.5 years, 176.9+7.3 cm, 70.9+8.6 kg). Interventions Five head kicks (round kick (RK), front leg axe kick, clench-axe kick (CA), jump spin back kick, jump spin hook kick (JH)) were randomly performed five times each. A Hybrid II Crash Dummy head (H2D) was instrumented with a tri-axial accelerometer (PCB Piezotronics-356A66) mounted inside the H2D head. The H2D was fixed to a height adjustable frame and fitted with a protective TKD helmet. Acceleration data were captured using Qualisys Track Manager (Gothenburg, Sweden) and processed in accordance with SAE J211-1. Main outcome measurements RLA, HIC and HVEL. Results The RK (130.11±51.67 g) produced a higher RLA than the CA (54.95±20.08 g, p<0.001, d=1.84) and a higher HIC15 than the JH (672.74±540.89 vs 300.19±144.35, p<0.001, ES=0.97). The range of the RLA by the RK was 60.50-217.33 g, while the CA was 26.34-99.02 g. The HIC15 range for the RK was 128.40-1608.70 and the JH, 63.90-573.00. There was no difference in HVEL of the RK (4.73±1.67 m/s, range: 3.36-9.52 m/s) and that of the JH (4.43±0.78 m/s, range: 3.00-5.54 m/s) (p=0.977, ES<0.01). Conclusion Our investigations are the first to identify the high-magnitude head impacts in TKD. A previous report suggests an HIC15 concussion threshold of >200. The RK is of concern because it is the most common technique and most common cause of concussion in TKD and has a high RLA and HIC15. Prevention of concussion in TKD should focus on employing qualified medical personnel, injury monitoring, and safer equipment.

quinta-feira, 24 de março de 2011

quarta-feira, 23 de março de 2011

terça-feira, 22 de março de 2011

Artigo sobre o impacto dos chutes no TKD

Energy absorbed by electronic body protectors from kicks in a taekwondo competition

F.B. Del Vecchio, E Franchini, A.H.M. Del Vecchio, W Pieter
Biol Sport 2011; 28 (1):
Objective: Although some scientific information on electronic body protectors in taekwondo is available, no research has been done to assess the impact of kicks in a competitive situation. The purpose of this study, then, was to assess the energy absorbed by these protectors from kicks performed in an actual taekwondo competition. Methods: Subjects consisted of junior (14-17 years) and senior (≥18 years) male taekwondo-in, who participated in an open tournament. Data on the energy imparted by valid kicks in Joules (J) were collected from a public visual electronic monitor. Results: Energy was higher for the seniors: 264.31 ± 56.63 J versus 224.38 ± 48.23 J for the juniors (eta2 = 0.121). The seniors scored lower in percent impact but the effect was trivial: 123.46 ± 24.77% versus 136.70 ± 26.33% (eta2 = 0.087). Conclusions: The difference between senior and junior taekwondo-in in absolute energy generated was small, while the difference in relative energy impact was trivial in favour of the junior taekwondo athletes.

http://biolsport.com/fulltxt.php?ICID=935878