Foxdal, P., Sjodin, A., & Sojdin, B. (1995). Comparison of blood lactate concentrations obtained during incremental and constant intensity exercise. International Journal of Sports Medicine, 17, 360-365.

Differences in blood lactate concentrations obtained during step-wise incremental and constant running exercise at the same intensities were investigated. Increments of 5 x 4, 5 x 6, and 5 x 8 minutes were compared on a running treadmill.

The following were found.

• Exercise increments of 4 or 6 minutes result in non-steady-state blood lactate concentrations.
• The 4.0 mM OBLA prediction of the maximum lactate steady state is inaccurate for highly-trained endurance runners.
• Compared to the 8-minute duration, the use of 4- or 6-minute exercise intervals during an incremental-intensity test produces results that overestimate maximal lactate steady state exercise intensity for endurance trained runners.

Implication. When testing athletes who have performed considerable endurance work, and an incremental test is used to assess anaerobic threshold, maximum lactate steady state, etc., the duration of each increment needs to be quite long because short-period intervals will lead to erroneous inferences. For trained runners, 8 minutes appears to be the minimum period to be spent at each step of an incremental testing procedure.

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