How many hours a week to train for a 50 km, 100 km or 100 mile race

It's the first question most runners ask when they sign up for an ultra: how much training will this take? There's no single answer, because it depends on the race, your history and the time you really have. But there are useful ranges, and there are things that matter more than the number on your biggest week. This guide gives both.

Count hours, not kilometres

On trails, kilometres lie. Ten kilometres with 800 metres of climbing can take twice as long as ten flat kilometres, and cost your body about as much as that time suggests. Race-day effort is measured in hours too: a 100 km mountain race can take anywhere from 12 to 30 hours. Counting training in hours, with elevation gain as the second number, keeps hilly weeks and flat weeks comparable.

Hiking counts too. On a mountain course you'll hike every steep climb, so training hours spent hiking briskly uphill, with poles if you race with them, are race-specific training, not a lesser kind of session. Cycling or ski touring can add aerobic hours with less impact, though they don't replace running for the legs and feet.

Typical ranges for peak weeks

These ranges describe the biggest weeks of a season, usually in the last block before the taper. Most weeks will be lower, and easier weeks lower still. They're drawn from common coaching practice for amateur runners, not from a formula: use them to sanity-check a plan, not to set one.

Elite runners train far more, often 15 to 25 hours a week, but they also have years of build-up behind them. Copying their weeks without their history is a reliable route to injury.

Where you start matters more than where you end

The right peak depends mostly on what you're doing now. A sensible season raises your weekly hours by about half, sometimes up to double, between the start of the base phase and the biggest weeks. If you run 5 hours a week today, an 8 to 10 hour peak is realistic; jumping to 15 is not. If the gap between where you are and where the race needs you to be is too big, choose a later race or a shorter one.

Our guide to planning an ultra-trail season shows how the hours rise block by block, with an easier week to close each block.

What matters more than the peak week

Consistency

Twenty weeks at 8 hours do more than ten weeks at 8 hours with an injury in the middle. The best predictor of a good race is months of steady training, not a heroic fortnight. If a plan leaves you exhausted every Monday, it's too big.

Long days

An ultra is mostly about holding a steady effort for many hours. Long runs of 3 to 6 hours, sometimes two in a row over a weekend, train that better than an extra midweek session. They're also where you practise eating, pacing and your kit. Our guide to eating on long runs covers the food side.

The race's climbing

Divide the race's elevation gain by its distance. A race with 50 metres of climbing per kilometre needs training with a similar ratio in the last blocks, including the descents. A flat 15-hour week won't prepare you for a mountain race the way a hilly 10-hour week will.

Mostly easy

Most of those hours should be easy: about three quarters or more of your training time at a conversational effort, hiking the steep climbs. A few harder sessions a week are enough. More hours at a moderate effort is the classic way to end up tired without getting fitter.

Strength

One or two short strength sessions a week protect your legs, especially for descents. Count them in your weekly hours so the week isn't heavier than it looks.

A sample peak week for a 100 km race

Here's how about 11 hours can be spread over a week in the build phase, for a runner with a full-time job. The numbers matter less than the shape: one long weekend, one quality session, the rest easy.

The next week might be similar, the one after a little bigger, and then an easier week at around two thirds of this. Peak weeks are only a few weeks of the season; most weeks are smaller.

When you can't train that much

Plenty of runners finish 100 km races on 7 or 8 hours a week. If your time is limited:

• Protect the long run first; it's the session the race depends on most.
• Make short weekday runs count: hills, stairs, or a short steady effort.
• Use a weekend with two long days once a month instead of a big week every week.
• Choose a race that suits your training: a course with less climbing, or generous cut-off times.
• Arrive rested: a limited plan done fully beats a big plan done half-injured.

Signs the volume is too high

Your body tells you before your calendar does. Persistent heavy legs, a resting heart rate a few beats above usual for days, heart-rate variability below your normal range, poor sleep, or aches that last more than a few days all say the same thing: hold the hours for a week or two, or take the easier week early.

Read next

• How to plan an ultra-trail season, phase by phase
• The taper for an ultra, week by week

Sources

1. Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 2010; 5(3): 276–291.