A comparative study of lactate threshold testing outcomes: walking vs. running.

Background: Although lactate threshold (LT) tests are widely used by athletes to evaluate endurance performance, such tests are not commonly applied in health controls among recreationally active subjects. This study aimed to investigate the test-retest reliability of walking as an exercise modality during LT testing and compare the test outcomes with those obtained during running.

Methods: Twenty-three male and female participants (25±3 year, 172±8 cm, 70±13 kg, and maximal oxygen consumption [VO2max] 51±5 mL·kg^-1·min^-1) performed four LT tests within 2-3 weeks, either using walking or running (two tests in each condition) protocols. The running tests were performed on a flat treadmill, and the pace increased by 1 km·h^-1 for each stage. During the walking tests, the pace was set to 6.5 km·h^-1, and the incline increased by 2.5% for each stage. LT was determined based on a fixed blood lactate concentration of 4.0 mmol·L^-1.

Results: Similar reliability values were observed for the walking and running protocol, and all between-trial differences were trivial or small. Significantly lower heart rate at LT was observed for the walking vs. running condition, but all between-modality differences were trivial or small. Analysis revealed that LT occurred at a slightly lower workload in walking than running (11.4±1.4 vs. 12.0±1.3 metabolic equivalents [METs]).

Conclusions: Given the trivial to small differences in LT variables observed between running and walking, these two protocols cannot be used interchangeably. However, the present study shows that walking represents an alternative exercise modality during LT testing in recreationally active subjects.