Tolerance to high-intensity intermittent running exercise: do oxygen uptake kinetics really matter?

Area of Science:

• Exercise Physiology
• Sports Science
• Human Performance

Background:

• High-intensity intermittent (HIT) running is a common exercise modality in team sports.
• Understanding the physiological determinants of HIT tolerance is essential for optimizing training.
• Previous research has explored factors like aerobic fitness and metabolic responses, but their specific roles in HIT tolerance require further clarification.

Purpose of the Study:

• To investigate the associations between aerobic fitness (VO2max), metabolic control (VO2 kinetics), locomotor function, and physiological responses during HIT running in team sport players.
• To identify key physiological factors that differentiate players with high versus low HIT tolerance.

Main Methods:

• Eleven team sport players underwent assessments for VO2max, velocity at VO2max (vVO2max), maximal sprinting speed (MSS), and VO2 kinetics.
• A standardized HIT protocol (8 sets of 10 x 4-s runs) was performed, monitoring cardiorespiratory variables, muscle oxygenation, electromyography, and blood lactate ([La]).
• Players were categorized based on their ability to complete HIT sets (≥5 sets vs. ≤2 sets).

Main Results:

• Metabolic responses during the initial sets of HIT were negatively correlated with VO2max, vVO2max, and VO2 SEV (recovery VO2), suggesting higher fitness is linked to better initial metabolic handling.
• Players completing more HIT sets (≥5) exhibited significantly greater vVO2max and MSS compared to those completing fewer sets (≤2).
• While VO2max and vVO2max were associated with HIT tolerance, VO2 kinetics measures did not show significant differences between high and low tolerance groups.

Conclusions:

• Maximal oxygen uptake (VO2max) and the velocity at which it occurs (vVO2max) are likely key determinants of tolerance to HIT running exercise in team sport players.
• The role of VO2 kinetics, as assessed in this study, appears less critical for determining HIT running tolerance within this population.
• These findings can aid practitioners in personalizing training interventions by focusing on aerobic capacity and speed-related parameters for improving HIT performance.