Workload impact on gender-based differences in delta blood lactate concentrations from supramaximal exercise

BACKGROUND: Gender-based delta blood lactate concentration (Delta[BLa-]) differences may be impacted by the volume of work performed during exercise. Thus workload can act as a confounding influence when data from men and women are compared. OBJECTIVE: To examine workload's impact on gender-based disparities in delta blood lactate concentration (Delta[BLa-]) values from supramaximal exercise. METHODS: Subjects (49 women, 31 men) did two workouts on an exercise device (Impulse Technologies; Newnan, GA) comprised solely of either tonic or phasic repetitions. Total work (TW) and Delta[BLa-] were quantified from each workout. TW and raw Delta[BLa-] values were each examined with 2 x 2 ANOVAs, with repeated measures for workout. Delta[BLa-] values were also examined with TW as a covariate using a 2 x 2 ANCOVA and repeated measures for workout. RESULTS: Raw Delta[BLa-] and TW results each yielded predictable inter-gender differences. However our ANCOVA data produced a two-way interaction and the following significant differences: men-phasic, women-phasic > women-tonic > men tonic. CONCLUSIONS: Our results support the idea that the volume of TW performed exacerbates inherent metabolic differences among men and women that heighten gender -based blood lactate differences. Future research on inter-gender lactate differences should consider workload as a covariate.