segunda-feira, 24 de fevereiro de 2014

Dois artigos sobre esportes de combate na edição de março do IJSPP

Time–Motion Analysis and Physiological Responses to Karate Official Combat Sessions: Is There a Difference Between Winners and Defeated Karatekas?

2014, 9, 302 – 308
PurposeThe aim of this study was to measure and compare physiological and time–motion variables during karate fighting and to assess eventual differences between winners and defeated elite karatekas in an ecologically valid environment. MethodsFourteen elite male karatekas who regularly participated in national and international events took part in a national-level competition. ResultsThere were no significant differences between winners and defeated karatekas regarding all the studied variables. Karatekas used more upper-limb (76.19%) than lower-limb techniques (23.80%). The kisami-zuki represented the most frequent technique, with 29.1% of all used techniques. The duration of each fighting activity ranged from <1 s to 5 s, with 83.8% ± 12.0% of the actions lasting less than 2 s. Karatekas executed 17 ± 7 high-intensity actions per fight, which corresponded to ~6 high-intensity actions per min. Action-to-rest ratio was about 1:1.5, and high-intensityaction- to-rest ratio was ~1:10. The mean blood lactate response at 3 min postcombat (Lapost) elicited during karate fighting was 11.18 ± 2.21 mmol/L (difference between Lapre and Lapost = 10.01 ± 1.81 mmol/L). Mean heart rate (HR) was 177 ± 14 beats/min (91% ± 5% of HRpeak). Karatekas spent 65% of the time exercising at HR >90% of the individual HRpeakConclusionKaratekas predominantly use upper-limb karate techniques. Karate’s nature is intermittent, with fighting activities representing ~6% of total combat’s duration and ~84% of actions lasting less than 2 s, with ~21-s mean time interval in between. Kumite combat sessions induced high La and near-maximal cardiovascular strain. Other key success factors should be investigated to properly discriminate winners and defeated athletes.
Keywordskarate kumite, physiological parameters, activity profile

The Energetics of Semicontact 3 x 2-min Amateur Boxing

2014, 9, 233 – 239
The energy expenditure of amateur boxing is unknown. PurposeTotal metabolic cost (Wtot) as an aggregate of aerobic (Waer), anaerobic lactic (W[lactate]), and anaerobic alactic (WPCr) energy of a 3 × 2-min semicontact amateur boxing bout was analyzed. MethodsTen boxers (mean ± SD [lower/upper 95% confidence intervals]) age 23.7 ± 4.1 (20.8/26.6) y, height 180.2 ± 7.0 (175.2/185.2) cm, body mass 70.6 ± 5.7 (66.5/74.7) kg performed a semicontact bout against handheld pads created from previously analyzed video footage of competitive bouts. Net metabolic energy was calculated using respiratory gases and blood [lactate].ResultsWaer, 526.0 ± 57.1 (485.1/566.9) kJ, was higher (< .001) than WPCr, 58.1 ± 13.6 (48.4/67.8) kJ. W[lactate], 26.2 ± 7.1 (21.1/31.3) kJ, was lower (< .001) than Waer and WPCr. An ~70-kJ fraction of the aerobic energy expenditure reflects rephosphorylation of high-energy phosphates during the breaks between rounds, which elevated Wtot to ~680 kJ with relative contributions of 77% Waer, 19% WPCr, and 4% W[lactate].ConclusionsThe results indicate that the metabolic profile of amateur boxing is predominantly aerobic. They also highlight the importance of a highly developed aerobic capacity as a prerequisite of a high activity rate during rounds and recovery of the high-energy phosphate system during breaks as interrelated requirements of successful boxing.
Keywordscombat sports, lactate, oxygen, heart rate

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