Very Short (15 s - 15 s) Interval-Training Around the Critical Velocity Allows Middle-Aged Runners to Maintain V˙O2 max for 14 minutes - Billat, V L; Slawinksi, J; Bocquet, V; Chassaing, P; Demarle, A; Koralsztein, J P (International Journal of Sports Medicine, 2001)