NON INVASIVE PREDICTION OF BLOOD LACTATE RESPONSE TO CONSTANT POWER OUTPUTS FROM INCREMENTAL EXERCISE TESTS

We determined the ability of gas exchange analyses during incremental exercise tests (IXT) to predict blood lactate levels associated with a range of constant power output cycle ergometer tests. Twenty-seven he althy young men performed duplicate IXT and four 15-min constant power output tests at intensities ranging from moderate to very severe, bef ore and after a training program. End-exercise blood lactate levels we re approximated from superficial venous samples obtained 60 s after ea ch constant power output test. From IXT, the power outputs correspondi ng to peak oxygen uptake (W-max) and lactic acidosis threshold (W-LAT) , were determined. We examined the ability of four measures of exercis e intensity to predict blood lactate levels for power outputs above th e LAT: (1) power output (W), (2) power difference (W - W-LAT), (3) pow er fraction (W/W-max) and (4) power difference to delta ratio [(W - W- LAT)/(W-max - W-LAT)]. Correlation coefficients were r = 0.38, 0.69, 0 .75, and 0.81, respectively. The best linear regression prediction equ ation was: lactate (mmol . l(-1))= 12.2[(W - W-LAT)/(W-max - W-LAT)] 0.7 mmol . l(-1). This relationship was not significantly affected by training, despite increased values of LAT and peak oxygen uptake. Nor malizing exercise intensity to the range of power outputs between W-LA T and W-max provided an estimate of blood lactate response to constant power outputs with a standard error of the estimate of 1.66 mmol . l( -1).