The Efficacy of the Lactate Threshold: A Sex-Based Comparison

Abstract

The second lactate threshold (LT2) has previously been associated with endurance performance; however, comparisons between sexes are lacking regarding its efficacy. The aim of this study was to compare LT2between men and women, specifically regarding its (a) relationship with endurance performance and (b) capacity to establish training and competition intensities. Competitive male (mean ± SD: age, 27.7 ± 4.7 years; Vo2max, 59.7 ± 5.2 ml·kg·min-1; n = 10) and female (mean ± SD: age, 27.3 ± 6.2 years; Vo2max, 54.5 ± 5.3 ml·kg-1·min-1; n = 12) cyclists and triathletes completed an incremental cycle trial to volitional fatigue (for determination of Vo2max and LT2via the modified D-max method), a constant load (±5%) exercise trial of 30 minutes at LT2power output, and a 40-km cycle time trial. The LT2significantly correlated with 40-km cycling performance in both men (r = -0.69 to -0.77; p < 0.01-0.05) and women (r = -0.63 to -0.75; p < 0.01-0.05). All men sustained LT2power output for 30 minutes, compared with 82% of women. Despite LT2reflecting a similar heart rate, Vo2,and [La-] to those elicited during a 40-km time trial in both men and women, power output at LT2was 6% higher (p < 0.05) than mean time trial power output in women, with no significant difference in men. Based on these findings, sex-specific recommendations have been suggested in regard to the use of LT2for establishing performance potential, prescribing endurance training intensities and setting 40-km performance intensity.