Ultra Training Load: Is This Week a Lot?¶
Nobody tells you what a lot is.
You finish a week with nine hours on your feet and 6,000 feet of climbing, and you cannot tell whether that was a big week or the week before something starts to hurt. Most of the numbers you can find are built for road racing: miles, pace, a split per mile. None of them answer the question an ultrarunner has on a Sunday night. Is this a lot for me?
The answer is in your own record. Here is how to read it, by hand or on your phone.
Why an ultra is counted in hours¶
An ultra is any race longer than a marathon, from a first 50K to a 100-miler to a 24-hour race. On most of them, the course decides your pace. A mile up a rocky climb can take three times as long as a mile of flat road, and it costs more than three road miles.
That is why ultra coaches plan in time on feet: the total time you are out there moving, walking the climbs and stopping at the top included. Coaches at CTS (Carmichael Training Systems) put it plainly in their guide to how much training a 100-miler takes: weekly hours are a better measure of training stress than weekly miles once terrain gets involved. A slow six-hour day in the mountains is a big day, even if the mileage looks modest next to a road week.
Why this week has to be compared with your usual week¶
Forty miles is a heavy week for one runner and an easy one for another. What matters is the jump: this week against what your body has been used to lately.
Sports scientists call this the acute:chronic workload ratio. "Acute" is your last 7 days. "Chronic" is your usual week, averaged over the last 4 weeks (28 days). Divide the first by the second. A ratio of 1.0 means this week looks like your usual week.
The idea comes from Tim Gabbett's 2016 paper The training-injury prevention paradox in the British Journal of Sports Medicine. In the team sports he studied, athletes whose ratio stayed around 0.8 to 1.3 got hurt least, and injury risk rose sharply once a week ran past about 1.5 times their usual. Treat that 1.5 as a reason to look at your week, not a verdict that you will get hurt. The International Olympic Committee's consensus statement on load and injury the same year took up the same idea.
A caveat: that research was done on rugby, cricket and football players, and later reviews such as this 2020 systematic review in Sports Medicine found the running evidence thinner. The ratio is not a diagnosis, and it does not know how you slept.
For a deeper walk through the maths, see ACWR Explained.
How to work it out by hand¶
A notebook works.
- Write down your time on feet for each of the last 28 days. Include walking breaks and hikes. A long day on a mountain counts in full.
- Add up the last 7 days. Say it comes to 8 hours.
- Add up all 28 days and divide by 4. That is your usual week. Say it comes to 6 hours.
- Divide. 8 divided by 6 is about 1.3. This week is a bit more than usual, right at the top of the range most research calls ordinary.
Then look for your long days. Sort a year of runs by time on feet and look at the longest few. Those are the days your body has already proven it can handle, and they tell you more about readiness for a long race than any single week.
One more thing to write beside the hours: climb. A week with the same hours and twice the climbing is a different week, especially for your quads on the way down.
What the NavRun iPhone app shows you¶
All of this lives in the NavRun iPhone app, on two screens: Today and You. Both read the runs you already sync from Strava or Apple Health. Nothing here grades you or ranks you against anyone.
Today: your week, with twelve weeks behind it¶
iPhone. Free.
The top of Today is This week so far: your time on your feet, your climb and your miles since Monday. Behind it sits a chart of the last twelve weeks, so a good week has something to stand next to. You can switch the chart between time, climbing and distance. There is no pace chip.
When your next race is three weeks out or closer, its countdown and course numbers move to the top of the screen. That is roughly when most runners start easing off before race day (the taper).
From two weeks on, a small line counts your "weeks in a row with a run". It never counts a gap out loud.
You: your whole record on one page¶
iPhone. Free.
The You tab is one scrolling page with a row of pills that jump between sections: Overview, Trends, Load, Runs, Reports, Records.
- At the top: your hours on your feet since you started, with hikes counted.
- This year, week by week: hours each week since January 1, with race weeks marked and your long days ringed. A long day is your own longest 5% of time on your feet over the last year, and at least 90 minutes. It switches on once you have about 20 runs to measure.
- Training load: one number, your last 7 days against a usual week from the last 4. It is a plain sentence ("Your last 7 days are more than your usual 4 weeks.") and a bar with your usual range marked on it. The bar never changes color. Until there are 4 weeks of runs, it says "Building your baseline." One heads-up: this number counts miles from your road and trail runs, not hours. A mountain week with fewer miles and more hours can read lighter than it felt, so read it next to your hours and climb at the top of Today.
- Injury-risk alerts: when one is active, it opens right under your header and says what it is based on, your road-run miles or your heart-rate load. For example: "This week is well past your usual load. Based on your heart-rate load."
- Your runs: open a month at a time, with races and long days standing out. Search finds a run by its name, a note, or the race it was.
- Records: longest run, longest time on your feet, biggest week, most climbing in a run and in a week.
Reports you already have are free to read. A new one written each Monday is part of the Crew, NavRun's paid plan. Everything else here is free.
What it does not do yet¶
- Injury alerts read road runs. The miles-based alert and the heart-rate alert are worked out from runs recorded as road runs. A block built mostly on trails may not raise one yet.
- A race only shows as a race once it is linked to one on your race calendar. Marking a run as a race by hand is coming.
Newer to this, or building toward a first 50K? The baseline fills in as you run. Back after time away? The bar measures you against your last 4 weeks, not against a year ago.
Common Questions¶
What is a good training load ratio for ultra running?¶
Research on the acute:chronic workload ratio suggests injuries are least common when this week sits around 0.8 to 1.3 times your usual week. It comes mostly from team sports, so treat it as a guide.
Should I train by time on feet or by miles for an ultra?¶
Most ultra coaches plan in time on feet, because terrain changes how long a mile takes and what it costs you. Miles are still worth writing down beside the hours.
How do I know if this week is too much for me?¶
Compare your last 7 days with your average week over the last 4 weeks. A big jump is worth noticing, along with how you are sleeping and feeling.
What counts as a long day in NavRun?¶
Your own longest 5% of time on your feet over the last year, and at least 90 minutes. It is measured only against your own runs.
Does the NavRun training load bar turn red when I train more?¶
No. The bar never changes color. It says in a plain sentence whether your last 7 days are lighter than, beside, or more than your usual 4 weeks.
Are training load and injury alerts free?¶
Yes. Training load, injury-risk alerts, your runs, trends and records are free. The Crew, NavRun's paid plan, adds a new weekly report each Monday and race-day tools.
Is an injury-risk alert a diagnosis?¶
No. It is a signal that your recent load has jumped past your usual, and it says what it is based on. If something hurts, talk to someone who can look at it.
The short version¶
Your ultra is measured in hours, so count your training in hours. Compare this week with your usual 4 weeks, not with anyone else. Look at your long days to see what you have already proven. For more on why hours beat miles out here, read time on feet versus mileage, or see what NavRun's analytics show.
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