Pesquisar este blog



Quem sou eu

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

Arquivo do blog

segunda-feira, 21 de dezembro de 2009

Feliz 2010

Depois de um ano de muito trabalho, as merecidas férias.
Até 2010.

4 comentários:

  1. Scand J Med Sci Sports. 2009 Dec 18. [Epub ahead of print]

    Stress-related hormonal and psychological changes to official youth Taekwondo competitions.
    Chiodo S, Tessitore A, Cortis C, Cibelli G, Lupo C, Ammendolia A, De Rosas M, Capranica L.

    School of Medicine, University of Magna Graecia, Catanzaro, Italy.

    The aim of this study was to evaluate the effects of an official Taekwondo competition on the heart rate (HR), salivary alpha-amylase (sA-A), salivary free cortisol (sC), and Profile of Mood States (POMS) in 10 young male (14+/-0 years) and six female (13+/-1 years) athletes. POMS and hormones were measured 15 min before and directly after the competition. During the recovery phase (30 and 90 min), sA-A and sC were also measured. HR measured during the competition was expressed as a percentage of individual's maximal heart rate (%HR(max)) to evaluate the intensity of exercise. During the competition, athletes spent 65% of the time working at HR>90% of individuals HR(max). A significant increase (P<0.0001) in sA-A (115%) was observed at the end of the match. At 30 min of recovery, sA-A returned to the pre-competition level. The peak sC values were observed at 30 min of recovery (P<0.001), returning to the pre-competition level at 90 min of recovery. A gender difference (P=0.01) emerged only for sC, although a similar trend was observed for female and male athletes. Significantly higher post-match scores emerged for Anger-hostility (pre: 6.1+/-1.1, post: 11.2+/-1.9; P=0.03) and Depression-dejection (pre: 4.5+/-0.5, post: 10.2+/-1.9; P=0.006), whereas the reverse picture was observed for Vigour-activity (pre: 23.2+/-1.2, post: 16.3+/-1.7; P=0.0006). Taekwondo competition results in temporary changes in the stress-related parameters measured in this study. The present findings suggest that this experimental paradigm can represent a useful model for further research on the effects of various stressors (i.e., training and competition) in Taekwondo athletes of different levels (i.e., novice, international).

  2. J Can Chiropr Assoc. 2009 Dec;53(4):272-81.

    Nine year longitudinal retrospective study of Taekwondo injuries.
    Kazemi M, Chudolinski A, Turgeon M, Simon A, Ho E, Coombe L.

    This retrospective longitudinal study aims to describe reported Taekwondo injuries and to examine associations between competitor experience level, age and gender, and the type, location, and mechanism of injury sustained. Additionally, we examined whether recent rule changes concerning increased point value of head shots in adult Taekwondo competition had affected injury incidence.This study was a summation of 9 years of data of competition injury reports, which included 904 injury reports spanning 58 individual competitions. The data was collected on standardized injury reports at time of injury during competition. Care was provided to the athletes, but the type of care provided was not included in the study. Participants included athletes injured during competition who sought care by the health care team, and for whom an injury report was filled out. The data analysis was performed at the Canadian Memorial Chiropractic College.The three most common locations of presenting injury were the head (19%), foot (16%), and thigh (9%). The most common mechanism of presenting injury was found to be a defensive kick (44%), followed by an offensive kick (35%). The most commonly diagnosed injuries were contusions (36%), sprains (19%), and strains (15%). Coloured belts had a higher incidence of contusions, while black belts sustained more joint irritation injuries. Black belts were more likely to suffer multiple injuries. Colored belts suffered more injuries while receiving a kick, while black belts had a larger influence of past history of injury. We found no significant difference in location or type of injury when comparing pre versus post rule change. The most common locations of injury are head, foot, and thigh respectively, and are areas for concern when considering preventative measures. Colour belt competitors are more likely to sustain contusions, which the authors believe is due to more aggressive tactics and lack of control. Those more likely to be injured tend to be younger than 18 years. Recent rule changes have no significant effect on head injuries.

  3. Eur J Appl Physiol. 2009 Dec 29. [Epub ahead of print]

    Neuromuscular control adaptations in elite athletes: the case of top level karateka.
    Sbriccoli P, Camomilla V, Di Mario A, Quinzi F, Figura F, Felici F.

    Department of Human Movement and Sport Sciences, Faculty for Movement Sciences, Study University of Rome "Foro Italico", Piazza Lauro de Bosis 6, Rome, 00135, Italy, paola.sbriccoli@iusm.it.

    This paper aimed at investigating the neuromuscular response of knee flexor and extensor muscles in elite karateka and karate amateurs (Amateurs) during isokinetic knee flexion/extensions and during the execution of a front kick (FK). Surface electromyograms (sEMG) were recorded from the right vastus lateralis (VL) and biceps femoris (BF) muscles with a four-array electrode during maximal isometric knee flexion and extension (maximal voluntary contraction), during isokinetic contractions (30 degrees , 90 degrees , 180 degrees , 270 degrees , 340 degrees , 400 degrees /s), and during the FK. The level of VL and BF agonist (ago) and antagonist (ant) activation during the isokinetic and FK protocols was quantified through normalized sEMG root mean square value (%RMS(ago/ant-ISOK/FK)). VL and BF average muscle fiber conduction velocity (CV) was computed for isokinetic and FK. Isokinetic flexion and extension torques and knee angular velocity during FK were also assessed. Analysis of variance was used to test the effect of group, angular velocity, and task on the assessed variables (P < 0.05). Elite karateka showed higher isokinetic knee flexion torque when compared with Amateurs. For all angular velocities, VL and BF %RMS(ant-isokinetic) were lower in elite karateka, while their BF-CV(isokinetic) BF-CV(front kick) and BF %RMS(ant-front kick) values were higher. For VL and BF, %RMS(ago-front kick) was lower than %RMS(ago-isokinetic) in both groups. Elite karateka demonstrated a typical neuromuscular activation strategy that seems task and skill level dependent. Knee flexion torque and CV results suggest the presence of an improved ability of elite karateka to recruit fast MUs as a part of training induced neuromuscular adaptation.

  4. J Strength Cond Res. 2010 Jan 12. [Epub ahead of print]
    Evidence of a Double Peak in Muscle Activation to Enhance Strike Speed and Force: An Example With Elite Mixed Martial Arts Fighters.
    McGill SM, Chaimberg JD, Frost DM, Fenwick CM.

    1Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada; and 2Adrenaline Performance Center, Montreal, Quebec, Canada.
    McGill, SM, Chaimberg, JD, Frost, DM, and Fenwick, CMJ. Evidence of a double peak in muscle activation to enhance speed and force: an example with elite mixed martial arts fighters. J Strength Cond Res 24(2): 348-357, 2010-The main issue addressed here is the paradox of muscle contraction to optimize speed and strike force. When muscle contracts, it increases in both force and stiffness. Force creates faster movement, but the corresponding stiffness slows the change of muscle shape and joint velocity. The purpose of this study was to investigate how this speed strength is accomplished. Five elite mixed martial arts athletes were recruited given that they must create high strike force very quickly. Muscle activation using electromyography and 3-dimensional spine motion was measured. A variety of strikes were performed. Many of the strikes intend to create fast motion and finish with a very large striking force, demonstrating a "double peak" of muscle activity. An initial peak was timed with the initiation of motion presumably to enhance stiffness and stability through the body before motion. This appeared to create an inertial mass in the large "core" for limb muscles to "pry" against to initiate limb motion. Then, some muscles underwent a relaxation phase as speed of limb motion increased. A second peak was observed upon contact with the opponent (heavy bag). It was postulated that this would increase stiffness through the body linkage, resulting in a higher effective mass behind the strike and likely a higher strike force. Observation of the contract-relax-contract pulsing cycle during forceful and quick strikes suggests that it may be fruitful to consider pulse training that involves not only the rate of muscle contraction but also the rate of muscle relaxation.