Introduction: High-intensity interval training (HIT) has been used as an alternative to cardiorespiratory training performed continuously at submaximal intensity and over long periods. Objectives: Propose a treadmill HIT protocol and verify the influence of six HIT sessions with this protocol on ventilatory anaerobic thresholds (VATs) and substrate oxidation pattern during submaximal continuous exercise (SCE). Methods: Fifteen sporadically active subjects underwent maximal progressive testing

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... fore and after six HIT treadmill running sessions to determine peak oxygen uptake (VO2peak), peak velocity (Vpeak), and VATs followed by SCE to determine lipid (LIPox) and carbohydrate (CHOox) oxidation rates. The HIT sessions consisted of eight sets of 60s at 100%Vpeak, interspersed with 75s of passive recovery between sets and a 48h interval between sessions. Results: Our results showed increases in VAT intensities of 4.4% for VAT1 and 8.8% for VAT2, a decrease of 12.8% in CHOox and an increase of 23.7% for LIPox; accordingly, the relative energy derived from LIPox was 20.3% higher after the training period. Vpeak was ~15 km/h, producing intensities corresponding to ~84%VO2peak and ~91%FCpeak over the training period. Conclusion: The proposed protocol produced adaptations and intensities which are similar to those described in the literature, but unlike others, it can be applied in sporadically active individuals. Level of Evidence II; Comparative prospective study.