- Endurance athletes set the intensities of training sessions using blood lactate data from a maximal graded exercise test. Specifically, these intensities are set as a percentage of heart rate (HR) at lactate threshold (LT). Often, however, gas exchange threshold (GET) data is used as a predictor of LT as it is less invasive and less expensive. A correction equation exists to predict LT using GET, but a consistent relationship between the two has not been established. This study (1) examined the previously inconsistent relationship between the V-slope GET method and the Dmax LT method (LTDmax), and (2) determined if this relationship, as well as the GET vs 1.5mmol increase LT method (LT1.5), holds consistent across a range of fitness levels. Thirty-one subjects (mean age 24.3 ± 6.0 years) underwent a maximal graded exercise test, during which blood lactate and gas exchange data were collected. The heart rates associated with LT were determined using the Dmax and 1.5mmol increase methods, while GET was determined using the V-slope method. Repeated measures ANOVA was used to analyze the GET-LT relationship, Bland-Altman plots were used to assess the agreement between the LT and GET HRs, and plots were constructed of the GET-LT difference compared to GET expressed as a percentage of VO2max (GET%max) and compared to VO2max. There was no significant difference between GET HR and either of the LT HRs (P > 0.05). Bland-Altman plots of the HR differences vs. HR means showed individuals with higher mean threshold HRs experienced GET at a greater intensity than LTDmax and LT1.5; when compared to GET%max, the data showed a similar, albeit stronger, trend. While GET appears equivalent to LTDmax or LT1.5, it cannot serve as a replacement for LT measures in all individuals—comparisons using LT and GET need to account for training status as well. Moreover, future research should consider inter-individual differences when determining threshold. As this study showed an increased difference between threshold HR measures in more highly trained individuals, it is possible that gas exchange variables are more sensitive to changes in endurance training status than blood lactate variables.