EVALUATION OF BLOOD LACTATE ELEVATION AS AN INTENSITY CRITERION FOR EXERCISE TRAINING

We sought to determine whether exercise intensities not elevating bloo d lactate produce alterations in physiological responses to exercise a ssociated with training. Twenty seven sedentary young men performed fi ve cycle ergometer training sessions . wk(-1) for 5 wk. Training power outputs were randomized to power outputs corresponding to either 80% of the lactic acidosis threshold (LAT), 25%Delta or 50%Delta (where De lta is the difference between LAT and peak VO2 power outputs estimated from incremental exercise tests). Exercise sessions were 30 min for t he 50%Delta group and were proportionately longer for other groups, so that total work did not vary among groups. Before and after training, subjects exercised for 15 min (or to tolerance) at pretraining 80% LA T, 25%Delta, 50%Delta, and 75%Delta power outputs. Continuous O-2 upta ke, CO2 output, ventilation and heart rate, and end-exercise blood lac tate, norepinephrine, and epinephrine were measured. For the 80% LAT g roup, posttraining end-exercise values for the 75%Delta test were sign ificantly lower for each of these variables. There were similar reduct ions in each variable in all three training groups; no significant dif ferences among groups were seen. Thus, in healthy subjects exercise wh ich does not elevate blood lactate alters constant power output respon ses as effectively as exercise which elevates lactate, provided that t otal training work is the same.