Acute responses and muscle damage in different high-intensity interval running protocols.

BACKGROUND: Our study aimed to evaluate the acute responses and exercise-induced muscle damage of five different high-intensity interval training (HIIT) protocols adjusted by the maximum velocity obtained in the 30-15 Intermittent Fitness Test (VIFT).

METHODS: Sixteen well-trained intermittent sport players (mean ± SD; age, 24.6±2.7 years; V̇O2max, 58.3±5.9 mL/kg/min) participated in five different HIIT protocols separated by six days in between (P240: 4×4 min at 80% VIFT; P120: 7×2 min at 85%; P30: 2×10×30 s at 90%; P15: 3×9×15 s at 95%; P5: 4×6×5 s sprints). Blood lactate (La), blood pH, serum creatine kinase (CK), heart rate (HR), session rating of perceived exertion (session-RPE), delayed onset muscle soreness (DOMS) and countermovement jump (CMJ) height were measured.

RESULTS: A significant main effect for protocol (P<0.05) was found for the acute responses of HR, session-RPE and La with values increasing in longer intervals from P15 to P120 and P240 while blood pH responded inversely. In contrast, P5 produced the highest La concentration and blood pH decreases. Twenty-four-hour post-exercise CK, DOMS and the decrease in CMJ height were significantly higher after P5 compared to all other protocols (P<0.05).

CONCLUSIONS: HIIT protocols of different interval duration and intensity result in varying acute physiological and perceptual demands and exercise-induced muscle damage. Longer intervals with submaximal intensity lead to higher acute cardio circulatory responses, whereas sprint protocols induce the highest muscle damage and muscle soreness.