Principles of Periodisation
Understanding the Jack Daniels VDOT Methodology.
MyRunDiary is built on the mathematical foundation of Jack Daniels' VDOT formula. Unlike generic "Couch to 5K" plans, our algorithmic engine periodizes your training into four distinct physiological phases.
Why Train at Current Fitness?
The most common mistake runners make is training at their Goal pace. If you want to run a 20:00 5K, but your current fitness is a 25:00 5K, attempting to run your intervals at 20:00 pace will simply result in failed workouts, overtraining, and injury.
The VDOT formula calculates your Current Fitness and assigns exact paces (Easy, Threshold, Interval, Repetition) designed to stimulate maximum physiological adaptation without destroying your body.
The 4 Phases of Training
Phase I: Base Building
Focuses entirely on Easy (E) pacing to build capillary density, strengthen ligaments, and prepare the body for the heavy work ahead.
Phase II: Early Quality
Introduces Repetition (R) pace to improve running economy and raw speed, alongside Threshold (T) pace to improve lactate clearance.
Phase III: Transition Quality
The hardest phase. Replaces R-pace with Interval (I) pace to maximize your Aerobic Capacity (VO2 Max).
Phase IV: Final Quality & Taper
Focuses on Marathon (M) pace for race specificity, and significantly drops weekly mileage (tapering) to shed fatigue before race day.
Why 8-Week Plans Skip Phase I
If you select an 8-Week plan in the generator, the algorithm completely bypasses Phase I.
You should only select an 8-week plan if you have already been running consistently (3-4 times a week) for at least a month.
If you are starting from scratch, select a 12 or 16-week plan to ensure you build an aerobic base and avoid injury.