PURPOSE: To analyze the contribution of energetic systems in Tabata’s high intensity-interval training (HIIT) protocol according sprint number
METHODS: Sixteen physically active males attended to two experimental sessions. In the first one was performed an incremental test to identify the maximum oxygen uptake (VO₂max) and power output (pVO₂max). At the second visit, participants performed HIIT session composed by sprints lasting 20s at 170% of pVO₂max followed by 10s rest until volitional fatigue. For the aerobic system estimative, difference between relative rest VO2 and its values during the activity was used. For the lactic system, the peak of blood lactate ([La-]) after the session was considered. The rapid phase of excess of post-exercise oxygen consumption (EPOC_fast) was used for alactic system contribution. Participants were allocated in three groups, considering the number of sprints performed (G23 = 2 to 3, G45 = 4 to 5 or G67 = 6 to 7 sprints). Relative (%) energetic contribution were analyzed using two-way ANOVA (group x energetic system)
RESULTS: Participants exhibited 24.9±6 years old, 1.67±2.7 cm, 55.6±8.7 kg and a VO₂max = 55.6±8.7 mL/kg/min, with [La-] = 13.2±1.7 mmol/L and maximum heart rate = 184±9.3 bpm. For relative energetic contribution (% of aerobic, lactic and alactic respectively), G23 showed 32.3±11.9% (CI95%= 25.5 - 39.2), 24.2±3.9% (CI95%= 17.3 - 31.0) and 43.5±15.4% (CI95%= 36.6 - 50.3); G45 showed 46.3±7.9% (CI95%= 39.4 - 53.1), 22.7±3.9% (CI95%= 15.8 - 29.5) and 31.0±7.2% (CI95%= 24.2 - 37.9), and; G67 showed 60.2±2.3% (CI95%= 51.8 - 68.6); 19.2±2.1% (CI95%= 10.8 - 27.6) and 20.6±3.4% (CI95%= 12.2 - 28.9), with no differences between groups (F=0.0; p=1), differences between systems (F=33.30; p<.001) and statistical significant interactions (F=11.77; p<.001)
CONCLUSIONS: Performing 2 to 3 sprints was found higher anaerobic contribution and performing 6 to 7 sprints, higher aerobic contribution in Tabata’s protocol. No participantes performed eight sprints.