Jack Daniels
Coach and physiologist
Creator of the VDOT system and the E/M/T/I/R training paces. The pace ingredients are mainstream physiology; VDOT is a performance-derived proxy, not a measured VO₂max.
Jack Daniels (1933-2025) was an American exercise physiologist and coach, author of Daniels’ Running Formula. His VDOT system, developed with Jimmy Gilbert, turns a recent race result into a single fitness index that assigns training paces and predicts equivalent times across distances.
VDOT is widely useful and grounded in real regression work, but it is a performance-derived proxy rather than a measured VO₂max; Daniels himself called it a “pseudo-VO₂max”, because two equally performing runners get the same value regardless of their true laboratory capacity. The five training intensities, easy, marathon, threshold, interval and rep, reflect mainstream physiology, but the tidy claim that each intensity improves only its one named component is not well evidenced, and the race-equivalence predictions degrade at the marathon. See training philosophies.