NDU

A check-up for your training plan

Paste a plan written by ChatGPT, a coach or a magazine: Endu runs it through 43 checks drawn from training science and reference coaches' plans (volume progression, long runs, intensities, taper, what triathlon and swimrun need). Free, no account and no AI: every rule is public and sourced.

Rules updated on 6 October 2026

  1. 1Copy this message and send it to your AI (ChatGPT, Claude, Gemini, Vibe…) in the conversation that holds your plan.

    Convert the training plan of this conversation to JSON, with no comment at all, exactly in this format: {"sport":"running|trail|triathlon|swimrun","race":{"distanceKm":0,"elevationGainM":0,"triathlonFormat":"xs|sprint|olympic|half_ironman|ironman","goalTimeSeconds":0},"athlete":{"level":"beginner|intermediate|advanced","vmaKmh":0,"recentRace":{"distanceKm":0,"timeSeconds":0},"currentWeeklyKm":0},"weeks":[{"week":1,"recovery":false,"sessions":[{"day":1,"discipline":"run|bike|swim|swimrun|brick|strength|rest|race","kind":"easy|long|recovery|tempo|threshold|intervals|repetitions|race_pace|hills|fartlek|progression|technique|other","durationMin":0,"distanceKm":0,"elevationGainM":0,"intensity":"easy|moderate|hard|very_hard","hardMinutes":0,"paceSecPerKm":0,"bikeMin":0,"runMin":0,"swimMin":0,"openWater":true,"gear":["wetsuit","paddles","pull_buoy","shoes"]}]}]} Rules: every week of the plan up to the race, one entry per session; day = 1 for Monday … 7 for Sunday; recovery = true for a lighter week; brick = bike then run back to back (bikeMin, runMin); swimrun = a session alternating swims and runs (swimMin, runMin); hardMinutes = minutes faster than easy pace, warm-up and recoveries excluded; openWater = a swim in a lake or the sea; gear = kit worn while swimming; times in seconds, pace in seconds per kilometre. Only put what the plan says: invent nothing and leave out unknown fields.

    A plan from a coach, a book or a magazine: paste it into your AI along with this message.

  2. 2Paste its answer here, then run the check.

    The check runs in your browser: your plan is sent nowhere.

Why check a plan?

Assistants like ChatGPT have become many runners’ first coach. Their plans look serious, but when ten coaches rated them, those written from little information scored 2 out of 5; a study of eight assistants found inconsistent paces and plans almost identical from one level to the next.

The check replaces neither your AI nor your coach: it checks the numbers, with rules written in advance, the same for everyone.

What the check verifies

Each rule says where it comes from and how strong its evidence is: a study, a meta-analysis or coaches’ consensus. A consensus rule only says “to fix” when every source consulted agrees against the plan; otherwise it flags.

Goal (7)
Load and progression (4)
Intensities (6)
Race-specific work (5)
Taper (3)
Trail, triathlon, swimrun (15)
Structure (3)

Our own plans go through it too

Before judging other people's plans, we ran 150 of Endu's plans through the check: the site's 124 public plans (every distance, goal and programme) and 26 test profiles. It first served to fix our own engine: long runs growing more than 10 % from one week to the next, too many demanding sessions for beginners, swimrunners who never swam in their shoes. Since October 2026, none needs a re-check, and an automatic test checks it at every engine change. Some remarks remain, for instance on the number of demanding sessions in some triathlon weeks: we track them release by release.

Your AI can call the check itself

Add Endu's connector to your assistant: it can check a plan before giving it to you, tell whether a goal is realistic, compute your paces, predict a race time or your fueling, with Endu's calculations. Connector address:

https://www.endu.fr/mcp
  • Claude: Customize › Connectors › Add › Add custom connector. Official help
  • ChatGPT: On a paid plan: Settings › Security and login, turn on developer mode, then Settings › Plugins › + with the address above. Official help
  • Vibe (Mistral): Context › Connectors › + Add, “Custom MCP Connector” tab. Official help

Assistants’ menus change often: when in doubt, follow their official help (links above). The connector needs no account and stores nothing your assistant sends it.

FAQ

Does the check use artificial intelligence?
No. Every rule is a calculation written in advance, the same for everyone, with its source. Only the formatting of your plan goes through your own AI, on your side, before you paste its answer here.
Is my plan stored?
No. The check runs in your browser: nothing is sent to Endu.
Endu sells plans: is the check neutral?
The rules are public and sourced, and our own plans go through them first. The verdict depends on the plan’s numbers, not on its author. But the check is published by Endu, and we would rather say so.
What does “Re-check needed” mean?
That at least one point needs fixing before following the plan: a clear gap, shown by studies or agreed by every source consulted. For instance a long run that more than doubles, no taper before a marathon, or a goal far beyond what your race times predict. “Pass with remarks” flags points worth a look, nothing blocking.
What if my plan gives no durations or paces?
The check verifies what the plan says, and lists what it could not check for lack of information. The more precise the plan (durations, days, intensities, paces), the more complete the check.
Is this medical advice?
No. These are general benchmarks for healthy adults. No check can predict an injury: it compares a plan with what studies and coaches’ plans show.

A plan that passes every check, computed for you

Endu computes your plan from your race, your level and the days you have, then adjusts it to your feedback after every session. Free account: the first 2 weeks of your plan are included. The rest: 14-day trial, cancel anytime.

Create my plan

Check published by Endu, which sells training plans. The rules and their sources are public on this page.