The purpose of this study was to investigate the feasibility of nonin-vasive measure of lactate clearance by decremental exercise. Twenty-six female collegiate students volunteered as subjects. All subjects performed maximal incrememtal (Inc) and maximal decremental (Dec) exercise on a bicycle ergon-ieter. The results were as follows ;
　1 ) The oxygen uptake (Vo₂) during the Dec was significantly higher than those during the Inc at same work output.
　2 ) The changing rate of Vo₂ (⊿Vo₂/⊿W) and heart rate (HR ; ⊿HR/⊿W) corresponding to work output during the Dec were significantly higher than those during the Inc (P<0.001).
　3 ) The oxygen requirement during the Dec (29.62±6.38 l) was significantly higher than those during the Inc (27.29±5.79 l ; P<0.01).
　4 ) The blood lactate (HLa) corresponded to work output during the Dec were significantly higher than those during the Inc.
　5 ) No significant difference was noted between ventilatory threshold during the Inc (VTD ; 27.7±3.49ml/kg/min) and during the Dec (VTD ; 28.5±3.11ml/kg/min).
　6 ) There was significant difference between lactate threshold during the Inc (LTI ; 24.4±4.04 ml/kg/min) and during the Dec (LTD ; 19.2±3.74ml/kg/min). The onset of blood lacate accumulation during the Inc (OBLAI) was significantly higher than those during the Dec (OBLAD ; P <0.001).
　7 ) There was significant relationship between VTI and VTD, and the regression line was almost same as identity line (y = x).
　8 ) The breakpoint of the respiratory exchange ratio (R) was related only to VTD (r = 0.536 ; P<0.05).
　9 ) Significant difference was noted between OBLAI and OBLAD, but not in case of LTI and LTD.
　10 ) There was significant relationship between ⊿Vo₂/⊿W during the Dec and LTD (r = 0.412 ; P<0.05).
　These results might indicate the feasibility of noninvasive measure of lactate clearance (LTD) by Vo₂/⊿W during the Dec, and necessity of more detailed study to elucidate the validity of LTD as an index of lactate clearance.

DESCENTE SPORTS SCIENCE Vol.17/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE