Glossary
Running training glossary
Clear definitions of the training terms behind a Runapt plan: what each one means and how the app uses it to build and adapt your training.
- VDOT
- VDOT is a single number that represents your current running fitness, derived from a recent race or time-trial result and used to set training paces.
- Popularized by coach Jack Daniels, VDOT lets a plan translate one performance into precise easy, marathon, threshold, interval, and repetition paces. Runapt calculates your VDOT from a recent result and recalibrates it as you get fitter, so every workout targets the right intensity instead of a generic pace. VDOT pace calculator→
- Threshold pace
- Threshold pace is the effort you could sustain for roughly an hour, representing the intensity at which lactate begins to accumulate faster than your body clears it.
- Often called tempo or lactate-threshold pace, it is one of the highest-return intensities in distance training because it raises the speed you can hold before fatigue spikes. Runapt sets your threshold pace from your VDOT and prescribes threshold sessions at the right point in your plan.
- Easy pace
- Easy pace is a comfortable, conversational effort that builds aerobic fitness while keeping fatigue low.
- Most weekly mileage should be easy. Running easy days too hard is the most common training mistake, as it adds fatigue without adding fitness and compromises the quality of hard sessions. Runapt keeps easy paces honestly easy so the quality work lands. Easy run pace calculator→
- CTL, ATL, and TSB
- CTL (Chronic Training Load), ATL (Acute Training Load), and TSB (Training Stress Balance) are fatigue-model metrics that estimate your fitness, recent fatigue, and freshness.
- CTL is a long-term average of training load (fitness), ATL is a short-term average (fatigue), and TSB is CTL minus ATL (form/freshness). Runapt uses this model to judge how much load you can absorb and to time harder weeks and tapers so you arrive at race day fresh rather than flat. How Runapt adapts→
- Readiness
- Readiness is a daily estimate of how prepared you are to train hard, based on recent training load, recovery, and other signals.
- When readiness is low, pushing a hard session adds risk without much reward. Runapt reads readiness alongside your recent runs and reshapes the day by swapping intensity for recovery, or moving the key workout, instead of forcing a plan that no longer fits.
- Tapering
- Tapering is the planned reduction in training volume in the final days or weeks before a race so you arrive rested without losing sharpness.
- A good taper drops volume while keeping a little intensity, letting accumulated fatigue clear so fitness shows up on race day. Runapt builds the taper into your race block automatically based on the distance and your training load.
- Ghost-runner pacing
- Ghost-runner pacing is live, in-run guidance that shows whether you are ahead of or behind your target pace for the current session.
- Instead of checking raw pace and doing the math, you see your position against a virtual pacer set to the workout’s target. Runapt uses ghost-runner pacing so you can execute intervals and tempo efforts at the right intensity without overthinking.
- Negative split
- A negative split means running the second half of a run or race faster than the first half.
- Negative splitting is a reliable racing strategy because it avoids the early-pace overspend that causes late-race fade. Runapt’s pacing strategy and ghost-runner pacing help you hold back early and finish strong.
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