FIELD-TEST FOR MECHANICAL EFFICIENCY EVALUATION IN MATCHING VOLLEYBALL PLAYERS

Field tests were performed in 10 volleyball (VB) players (4 Females an d 6 males) in order to obtain an index of mechanical work efficiency ( mu' = W-mec/W-oxy) while athletes played a game. W-mec was the mechani cal work output, obtained by means of home made video image analysis s oftware, by summing potential, kinetic translational and kinetic rotat ional energies of running and jumping athletes. W-oxy was the oxidativ e energy consumption obtained from O-2 consumption (Vover dot O-2) by a telemetry device (Cosmed K2) that also gave values of pulmonary vent ilation (Vover dot(E)) and heart rate (HR). VB were studied at rest be fore a game (R), during attacking phases (A) and during defensive phas es (D). At R were found: Vover dot(E) = 11 +/- 1 l.min(-1), HR = 78 +/ - 7b.min(-1), Vover dotO(2) = 3.71 +/- 1.1 ml.kg(-1).min(-1), W-oxy = 75.1 +/- 22.3 (sic).kg(-1).min(-1). During A all variables increased V over dot(E) = 49 +/- 6 l.min(-1), HR = 149.15 b.min(-1), Vover dotO(2) = 23.1 +/- 3.3 ml.kg(-1).min(-1), W-oxy = 482.8 +/- 69.0 (sic).kg(-1) .min(-1), and W-mec 275.5 +/- 57.0 (sic).kg(-1).min(-1) with mu' = 0.5 7 +/- 0.09. In D HR (-9%), Vover dot(E), Vover dotO(2) and W-oxy (-18% ) were reduced when compared to A, decreasing mu' to 0.21 +/- 0.05. On the other hand mu' was found higher than 0.25 during A indicating an anaerobic contribution to energy expenditure; in D the mu' lower than 0.25 indicated a restoration of anaerobic energy sources. It might be proposed that a greater difference in mu' values between A and D also means a higher anaerobic energy contribution to the volleyball game.