How TERUN works
A transparent, debuggable coaching engine, not a black box that hands you a grid and hopes.
1. It estimates your fitness from raw data
TERUN fits the relationship between your pace and heart rate, using steady segments of your runs rather than whole-run averages that warm-ups and stops would distort. From that fit it reads your threshold pace and converts it to a predicted race time (via Riegel). The estimate is smoothed over roughly three weeks so it moves sensibly: one great session nudges it, it doesn’t jump.
2. It turns a goal into a periodized plan
Give it a race distance and date and it lays out a classic base → build → peak → taper progression. Target paces for every workout are derived from your fitness estimate, so they float: as you improve, the plan gets faster with you, and you never re-enter a goal pace.
3. It schedules your whole training week
- Cross-training: cycling and swimming add a small, conservative, decaying boost to your stamina estimate. Running is ground truth and overrides it at the next quality run.
- Strength: your exercise pool is composed into balanced sessions from your weekly frequency, and treated as a scheduling and recovery constraint.
- Shared fatigue account: every sport pays in, with sport-specific decay (strength and DOMS clear slower). It gates whether you’re fresh enough for a hard run, and downgrades heavy strength rather than let you overtrain.
4. It listens to how you feel
A daily check-in (“any pain? how do the legs feel?”) captures what sensors can’t. Leg feel, energy, sleep and pain produce a readiness score that can raise effective fatigue and modify today’s session: proceed → easier → swap to cross-training → rest → rest and see a physio. Pain is handled separately from fatigue: fatigue means “go easy,” pain means “don’t run on it,” and sharp or persistent pain always routes to rest, never push-through.
5. It stays honest about your goal
Each week it projects your trajectory to race day. If you’re off track it says so and suggests an achievable target. See is my race goal realistic?
What it isn’t. A very good adaptive planner, not a full coach. It sees pace, heart rate, and what you log or tell it, not your form, life stress, or an oncoming illness. Keep your judgment in the loop, and see a physio if something hurts.