The science behind Rurilab: VDOT, 80/20 and training load
Rurilab isn't magic and it isn't a black box. Its plans rest on three well-established ideas from endurance science. Understanding them makes every recommendation the app gives you easier to trust.
VDOT: one number for your current fitness
Coined by exercise physiologist Jack Daniels, VDOT is a practical measure of running fitness derived from race or hard-effort performances. Two runners with the same VDOT should train at similar paces, regardless of their raw lab numbers.
Its real power is translation: a VDOT maps directly to your training paces — easy, marathon, threshold, interval and repetition. Rurilab estimates your VDOT from your recent quality runs, so your prescribed paces follow your fitness as it rises and falls, instead of being frozen at sign-up.
80/20: a reference, not a universal prescription
Seiler's 2010 review describes an approximate distribution of low- and high-intensity sessions in highly trained endurance athletes. Counting sessions is not the same as counting minutes, and the finding does not prescribe one fixed split for every recreational runner or race.
Intensity distribution is useful context. The appropriate balance depends on experience, recent training, race demands and the runner's response; a percentage alone is not evidence of suitability.
Training load: CTL, ATL and TSB
Every session is stress; fitness is the body adapting to stress it can recover from. To keep that balance visible, Rurilab uses the classic impulse-response model popularized as the Performance Management Chart:
- CTL — Chronic Training Load: a long-term model of recorded stress, often used as a fitness proxy.
- ATL — Acute Training Load: a short-term model of recorded stress, often used as a fatigue proxy.
- TSB — Training Stress Balance: CTL minus ATL. A model balance, not a direct measurement of freshness or tissue recovery.
This is also how a sensible taper works: hold fitness (CTL) while letting fatigue (ATL) fall, so form (TSB) rises into race day.
Recovery signals: HRV, resting HR and sleep
Load models describe the training; recovery signals describe how you're handling it. Trends in heart-rate variability (HRV), resting heart rate and sleep add context when available. They do not diagnose injury or prove that it is safe to train. Recommendations must retain the uncertainty of the inputs and are not medical clearance.
Periodization: putting it in order
Finally, these pieces are sequenced over time — base, build, peak, taper — toward a goal race. Periodization organizes training; an impulse-response load model is a different tool. Neither proves that a specific athlete will recover or achieve a predicted result.
Put together — VDOT for paces, 80/20 for intensity, CTL/ATL/TSB for load, recovery signals for readiness, periodization for order — you get a plan that's demanding when you're ready and forgiving when you're not.
What the research does and does not establish
The IOC consensus on load and injury risk considers multiple influences, including recovery and injury history. It is not a validation of Rurilab's implementation. The app is still in development; no clinical validation or guaranteed performance improvement is claimed.
Editorial contact: Jan Kimla, Rurilab developer. jan@rurilab.com.