Critical velocity (CV) represents the boundary between the 'heavy' and 'severe' exercise domains. It is the maximum pace at which oxygen consumption and blood lactate stabilize. Above CV, anaerobic reserves (D') are progressively depleted and cessation becomes inevitable. In practice, CV roughly corresponds to 30-40 minute race pace. It is a more precise endurance performance predictor than VO2max alone.
CV = (Distance longue - Distance courte) / (Temps long - Temps court)If your CV is 15 km/h, you can theoretically sustain this pace (4:00/km) for 30-40 min. Training at CV pace specifically develops Type IIa muscle fibers.