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

Area of Science:

• Exercise Physiology
• Sports Science
• Training Adaptations

Background:

• High-intensity interval training (HIT) is a popular training method.
• Different HIT protocols may elicit distinct physiological responses and muscle damage.
• Optimizing HIT requires understanding the impact of varying interval durations and intensities.

Purpose of the Study:

• To evaluate the acute physiological responses and exercise-induced muscle damage from five distinct HIT protocols.
• To compare the effects of HIT protocols varying in interval duration and intensity, matched to maximal velocity from the 30-15 Intermittent Fitness Test (VIFT).

Main Methods:

• Sixteen well-trained intermittent sport players completed five HIT protocols with varying work/rest ratios and intensities.
• Measurements included blood lactate, pH, creatine kinase (CK), heart rate (HR), session rating of perceived exertion (session-RPE), delayed onset muscle soreness (DOMS), and countermovement jump (CMJ) height.
• Protocols ranged from longer intervals (e.g., 4x4 min at 80% VIFT) to short sprints (e.g., 4x6x5s sprints).

Main Results:

• Longer HIT intervals (P240, P120) elicited higher HR, session-RPE, and lactate, with inverse changes in blood pH.
• Shorter sprint protocols (P5) resulted in the highest lactate concentration and greatest decrease in blood pH.
• 24 hours post-exercise, P5 induced significantly higher CK, DOMS, and reduced CMJ height compared to other protocols.

Conclusions:

• HIT protocols with different interval durations and intensities induce varying physiological and perceptual demands.
• Longer intervals at submaximal intensities enhance acute card circulatory responses.
• Sprint-based HIT protocols lead to the most significant exercise-induced muscle damage and soreness.