Mixed
Speed endurance training (SET) improves intermittent recovery performance (Yo-Yo IR-2) significantly more than sprint training (ST), primarily through enhanced lactate clearance and potassium handling rather than just increased muscle mass or fiber type changes.
If your goal is to improve your ability to recover between high-intensity bursts (like in team sports), prioritize speed endurance intervals (e.g., 30-second runs at >130% VO2max) over pure sprints. This type of training specifically enhances your body's ability to clear lactate and manage ions during repeated efforts, leading to much larger gains in intermittent recovery capacity.
Improvement in the Yo-Yo intermittent recovery test was larger (P < 0.05) in the SET than ST group (29% vs. 10%)... In SET, the blood lactate concentration during the Yo-Yo test was lower after the training period, but higher at exhaustion, and the decrease in muscle lactate and increase in muscle pH were more pronounced during the first 3 min of recovery after training.
Why this rating
Clear performance metrics with statistical significance, though small sample size.
Source
Effect of two different intense training regimens on skeletal muscle ion transport proteins and fatigue development
Magni Mohr et al. · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2006
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →