This study examined the effect of exposure of the whole body to moderate cold on blood lactate produced during incremental exercise. Nine subjects were tested in a climatic chamber, the room temperature being controlled either at 30 degrees C or at 10 degrees C. The protocol consisted of exercise increasing in intensity in 35 W increments every 3 min until exhaustion. Oxygen consumption (VO2) was measured during the last minute of each exercise intensity. Blood samples were collected at rest and at exhaustion for the measurement of blood glucose, free fatty acid (FFA), noradrenaline (NA) and adrenaline (A) concentrations and, during the last 15 s of each exercise intensity, for the determination of blood lactate concentration [la-]b. The VO2 was identical under both environments. At 10 degrees C, as compared to 30 degrees C, the lactate anaerobic threshold (Than,la-) occurred at an exercise intensity 15 W higher and [la-]b was lower for submaximal intensities above the Than,la-. Regardless of ambient temperature, glycaemia, A and NA concentrations were higher at exhaustion while FFA was unchanged. At exhaustion the NA concentration was greater at 10 degrees C [15.60 (SEM 3.15) nmol.l-1] than at 30 degrees C [8.64 (SEM 2.37) nmol.l-1]. We concluded that exposure to moderate cold influences the blood lactate produced during incremental exercise. These results suggested that vasoconstriction was partly responsible for the lower [la-]b observed for submaximal high intensities during severe cold exposure.