Running plans for triathletes

Why a standard running plan breaks in a triathlon week

Marathon and half-marathon plans are built on one hidden assumption: the runs are the whole aerobic week. Drop that plan into a triathlon build and you're now doing its full running volume on top of hours of cycling and swimming. The plan can't see any of it, so it keeps progressing the run as if you were rested. This is the single most common way age-groupers arrive at a race either injured or flat — not from bad sessions, but from a plan that was never told about two thirds of the training.

The bike is training load, not filler

Cycling builds real aerobic fitness — cardiac output, capillarisation, fat oxidation, mitochondrial density. What it does not build is impact tolerance: the tendon, bone and connective-tissue resilience that only running loads. That asymmetry is the whole planning problem. A strong cyclist can be aerobically ready to run a half marathon months before their legs are structurally ready to absorb 21.1 km of ground contact. Your engine says go, your tissue says wait, and the plan has to obey the slower of the two.

Where the run sessions actually go

Most age-groupers run three times a week, and three well-placed runs beat five squeezed ones. Protect two of them: one quality session and one long run. Then apply the placement rules that matter more in triathlon than anywhere else — never put a hard run the morning after your biggest bike, keep at least one day between the long run and the long ride, and treat a brick run as a quality session in its own right, not a bonus tacked onto a ride. If your week only has room for two real runs, take two: consistency across twelve weeks beats a fourth run you abandon in week three.

What changes for the run leg specifically

In a race you never run fresh, so training only at fresh-legs pace prepares you for a race that doesn't exist. Your standalone half-marathon pace is not your 70.3 run pace, and the gap is usually far bigger than people expect. Do some race-pace work off the bike so you learn what that pace actually feels like with cycling in your legs, and rehearse the first three kilometres deliberately — that's where most run legs are lost, going out at a pace the bike has already spent. The brick guide covers when to place them and how hard to run.

What to ask of an AI coach if you're multisport

Three questions settle it. Can it see your bike and swim, or only your runs? Does it count them as load when it decides next week, or does it just display them? And will it tell you plainly what it does not model? Most running apps fail the first question outright: they read run activities and ignore the rest, which means their adaptation is blind to most of your week. Be equally suspicious of the opposite claim: a tool that says it plans all three sports should be able to explain how. Leo's answer is that he sizes the plan on your race's legs, writes the rides by power or by heart rate, writes the swims from your critical swim speed, and places the brick sessions in the closing weeks (the detail is on Coach Leo for triathletes, and format by format on sprint, olympic, half distance and full distance). What he will not claim is an overall finish time.

Frequently asked questions