ENERGY-COST AND ENERGY-SOURCES IN KARATE

Energy costs and energy sources in karate (wade style) were studied in eight male practitioners (age 23.8 years, mass 72.3 kg, maximal oxygen consumption (VO2max) 36.8 ml . min(-1) . kg(-1)) performing six katas (formal, organized movement sequences) of increasing duration (from approximately 10 s to approximately 80 s). Oxygen consumption (VO2) was determined during pre-exercise rest, the exercise period and the first 270 s of recovery in five consecutive expired gas collections. A blood sample for lactate (la(-)) analysis was taken 5 min after the end of exercise. The overall amount of O-2 consumed during the exercise and in the following recovery increased linearly with the duration of exercise (t) from approximately 1.5 1 (for t equal to 10.5 s (SD 1.6)) to approximately 5.8 1, for t equal to 81.5 s (SD 1.0). The energy release from la(-) production (VO2la-) calculated assuming that an increase of 1 mmol . l(-1) la(-) corresponded to a VO2 of 3 mlO(2) . kg(-1) was negligible for t equal to or less than 20 s and increased to 17.3 ml . kg(-1) (la(-) = 5.8 mmol . l(-1) above resting values) for t equal approximately to 80 s. The overall energy requirement (VO2eg) as given by the sum of VO2 and VO2la- was described by VO2eq = 0.87 + 0.071 . t (n = 64; r(2) = 0.91), where VO2eq is in litres and t in seconds. This equation shows that the metabolic power (VO2eq . t(-1)) for this karate style is very high: from approximately 9.5 l . min(-1) for t equal to 10 s to approximately 4.9 l . min(-1) for t equal to 80 s, i.e. from 3.5 to 1.8 times the subjects' VO2max. The fraction of VO2eq derived from the amount of O-2 consumed during the exercise increased from 11% for t equal to 10 s to 41% for t equal to 80 s whereas VO2la- was negligible for t equal to or less than 20 s and increased to 13% for t equal to 80 s. The remaining fraction (from 90% for t equal to 10 s to 46% for t equal to 80 s), corresponding to the amount of O-2 consumed in the recovery after exercise, is derived from anaerobic alactic sources, i.e. from net splitting of high energy phosphates during the exercise.