Effect of incremental test protocol on the lactate minimum speed

Purpose: The purpose of this study was to investigate the effect of alterin g the initial running speed (RS) in the incremental portion of the lactate minimum test on the lactate minimum speed (LMS). Methods: Eight well-traine d endurance runners (mean +/-SD age 29.0 +/- 5.4 yr, body mass 72.0 +/- 5.6 kg, (V) over dot O-2max 63.1 +/- 3.8 mL.kg(-1) min(-1))completed a standar d incremental treadmill rest for the assessment of the lactate threshold (L T) and (V) over dot O-2max and eight lactate minimum tests. Following a per iod of supramaximal exercise, subjects were allowed 8 min of recovery to al low blood [lactate] to peak. Subjects then undertook eight randomly-assigne d incremental treadmill tests from different initial running speeds (3.0, 2 .5, 2.0, 1.5, 1.0, and 0.5 km.h(-1) below the predetermined RS-LT, at the R S-LT, and at 1.0 km.h(-1) above the RS-LT) with RS increased by 1.0 km.h(-1 ) every 5 min until volitional fatigue. Blood samples for the determination of blood [lactate] were taken at the end of each stage and the LMS was det ermined by fitting a spline function to the data. Results: No LMS could be determined for the two highest initial RS conditions. For the other conditi ons, the LMS was significantly affected by the initial RS used in the incre mental test and varied from 13.8 +/- 0.7 km.h(-1) with an initial RS of 3.0 km.h(-1) below the RS-LT, to 15.8 +/- 0.8 km.h(-1) with an initial RS of 0 .5 km.h(-1) below the RS-LT. The LMS was significantly different from the R S-LT (15.4 +/- 0.8 km.h(-1)) (P < 0.05), except when the incremental test s tarted at 1.0 or 1.5 km.h(-1) below the RS-LT. Conclusions: These results s uggest that the LMS rest is not a valid method for estimation of the LT sin ce it is profoundly influenced by the starting speed selected for the incre mental portion of the rest.