The reproducibility of the 4 mmol/l lactate threshold in trained and untrained women

Lactate threshold measurements are part of the routine testing done for training and diagnostic purposes. The reproducibility of the 4 mmol.l-1 threshold has, however, rarely been investigated. Twenty-seven untrained and 10 endurance-trained females each performed two incremental spiroergometric treadmill tests at 5% grade, with three-minute speed increase intervals. Running speed at the threshold increased from 1.9 to 2.1 m.sec-1 in the untrained and remained constant at 3.4 m.sec-1 in the trained group. Heart frequency and oxygen uptake did not change significantly in either group. The variability of changes between untrained individuals expressed by correlation coefficients was r = 0.63 for oxygen uptake, 0.55 for running speed and 0.42 for heart frequency. These figures for the trained persons were r = 0.61; 0.92 and 0.88 respectively. The higher reproducibility of the anaerobic threshold in trained women supports the high value attached to the anaerobic threshold in training guidance. For untrained women, training recommendations of the basis of treadmill tests must consider treadmill running speed to be 0.14m.sec-1 higher than initially achieved during the first test because of coordination problems. Training-guidance-based heart frequency must take into account a higher variability for untrained than for trained females.