A 10K run at full effort produces the one number that shapes every pace in your training block — so the plan reflects your real fitness, not a wish-list finish time.
- You run the test over 10K under controlled conditions, and the average pace becomes the reference point for the entire block.
- From that number, you derive your easy, steady, half marathon race, and interval paces by simple offsets.
- The plan runs twelve weeks: the test lands in week one, the race in week twelve.
- Retesting at the midpoint only makes sense if you replicate the original conditions.
Most half marathon plans get abandoned at the same point, around week three. That breaking point happens because the paces on the page are faster than the runner’s real fitness: the fatigue builds session after session until the next one becomes unmanageable. Reversing the order fixes the problem at the root. Measure first. Write the plan second.
Why a Plan Built Around a Goal Time Stops Working
A plan built from a goal time assigns every session a pace derived from a performance that doesn’t exist yet. A goal time isn’t an input. It’s an outcome.
The initial gap doesn’t stay contained, either. Overestimate your reference pace by fifteen seconds a mile, and every derived pace inherits the error: easy turns into a mild steady effort, steady creeps toward race pace, intervals demand a full day of recovery instead of one, and the fast-finish long run becomes unworkable. Within three weeks, the pile-up produces skipped sessions, and the plan stops describing what you’re actually doing.
A measured test gives you a number that belongs to today’s fitness. The 10K is the right distance for the job: long enough that raw top-end speed doesn’t decide it, short enough to run flat-out without burning the following week in recovery.
Running the 10K Test So the Data Holds Up
A test is only as good as its repeatability. Run it with a tailwind on a course that drops slightly downhill, and the number describes the route more than your fitness — every pace you derive from it will run too fast.
Prep starts a few days out. Push your weekly long run to at least three days before the test, and in the 48 hours beforehand, run short and easy or skip running altogether. The warm-up is part of the protocol, and it needs to be identical every time you repeat the test: fifteen minutes of easy running, three strides of 80-100 meters with full recovery, five minutes of walking before you start. Log the shoes you wore, too — if you retest someday in a more responsive model, the comparison between the two numbers won’t be clean.
Course, Time of Day, and Pacing the Opening Kilometers
You need a flat, accurately measured course. A repeated 1.2- or 1.5-mile loop works well, and so does a 5K (3.1-mile) out-and-back, which cancels out a constant grade and largely neutralizes wind. The track remains the most precise option: twenty-five laps is monotonous, but the distance is certain and there are no lights to break your rhythm. Rule out uneven trails, routes with intersections, and any stretch where you have to slow down for reasons that have nothing to do with your legs.
The right time is early morning, before the temperature climbs. In August and early September, humidity matters more than the number on the thermometer: dew point is the indicator to check the night before, to decide whether the test is worth pushing back 24 hours.
How you handle the opening kilometers decides the quality of the data. Run the first kilometer five to ten seconds slower than the average pace you think you can hold, the second in line with that pace, and from there, judge whether you have room to pick it up. Your fastest kilometer should land in the final three. The same effort-distribution logic that applies to negative-split racing protects the data here: start too fast, and you fade in the second half, leaving a finish time that undersells your fitness.
When you finish, log the total time, the split for each kilometer, and a line on how the final three went. If there’s more than a twenty-second gap between your fastest and slowest kilometer, the test is usable but imprecise: the average pace comes from uneven pacing, and it’s worth repeating after about ten days.
From Test Numbers to Session Paces
The test’s average pace — which we’ll call your test pace for the rest of this piece — comes from dividing your total time by 6.2. A test finished in 50:00 gives a test pace of about 8:00/mile. Every other pace in the plan is derived from that number by a fixed offset.
| Zone | How It’s Derived from Test Pace | Example at an 8:00/Mile Test Pace |
|---|---|---|
| Easy pace | +1:40 to +2:05 per mile | 9:40-10:05/mile |
| Steady pace | +45 to +60 sec per mile | 8:45-9:00/mile |
| Half marathon race pace | +25 to +35 sec per mile | 8:25-8:35/mile |
| Long intervals (1000-2000 m) | Test pace to about 5 sec faster per mile | 7:55-8:00/mile |
| Short intervals (400-800 m) | 10 to 20 sec faster per mile | 7:40-7:50/mile |
The order of these zones deserves a note, because at first glance it looks like a typo: steady pace is slower than half marathon race pace. That’s intentional. Steady work is there to bank minutes at a sustained intensity without paying the cost of a race-pace session, and keeping it just below that threshold is exactly what lets it coexist with the rest of the week’s training.
Half marathon race pace also projects a finish time: 8:25-8:35 per mile over 13.1 miles (21.1K) works out to a finish between 1:50:46 and 1:52:32. It’s a projection, with all the usual caveats. The twelve weeks of work exist for exactly one purpose: making a pace you can hold for 6.2 miles today sustainable for 13.1.
In the first two weeks, check these zones against how you actually feel. If easy pace feels unnaturally slow, stay in the zone anyway: that sensation usually means your easy runs had been creeping faster than useful. If your intervals close with the last rep noticeably slower than the first, your test pace was inflated, and it’s worth pulling every zone back by about eight seconds per mile.
The Week-by-Week Plan
Three sessions a week, with at least one rest day between the quality workout and the long run. Tuesday, Thursday, and Sunday is one schedule that works. Any additional runs are easy-paced and don’t replace any of the three.
The Intervals. After fifteen minutes of easy running and three strides, run each repeat at the pace prescribed for that zone, settling into it within the first hundred meters and holding it to the finish. Recover at a very easy jog, never standing still, for the duration listed. Close with ten minutes easy. Success here means consistency: the last repeat should clock the same time as the first. For the longer distances in the table, the same logic applies as in our piece on long intervals in half marathon training.
The Steady Run. This is a continuous block inside a longer outing. Ten to fifteen minutes easy to settle in, then the block at the prescribed pace with no breaks, then ten minutes easy to close it out. The discipline is in not speeding up: a steady run pushed fifteen seconds a mile faster than prescribed costs as much as a full quality session and delivers far less.
The Long Run. In the early weeks, run it entirely at easy pace, with duration as the only variable that grows. From week four on, a faster finish appears, first at steady pace and then at half marathon pace, which rehearses managing fatigue in the closing miles. The structure follows the general principles laid out in our piece on the weekly long run.
| Week | Easy Run | Quality Session | Long Run |
|---|---|---|---|
| 1 | 5 miles easy | 10K Test | 7.5 miles easy, at least 48 hours after the test |
| 2 | 5 miles easy | 5 x 1000 m long intervals, 2-minute recovery | 8.5 miles easy |
| 3 | 5 miles easy | 20 minutes steady inside a 10K outing | 9.5 miles easy |
| 4 | 5.5 miles easy | 6 x 1000 m long intervals, 90-second recovery | 10 miles, last 2 miles steady |
| 5 | 5 miles easy | 8 x 600 m short intervals, 2-minute recovery | 7.5 miles easy (recovery week) |
| 6 | 5.5 miles easy | 30 minutes steady inside a 7.5-mile outing | 10.5 miles, last 2.5 miles at half marathon pace |
| 7 | 10K easy | 2 x 3000 m at half marathon pace, 3-minute recovery | 11 miles easy |
| 8 | 10K easy | 3 x 3000 m at half marathon pace, 3-minute recovery | 12 miles, last 5K at half marathon pace |
| 9 | 5 miles easy | 10K retest, or 8 x 800 m short intervals, 2-minute recovery | 8.5 miles easy |
| 10 | 10K easy | 40 minutes steady inside an 8.5-mile outing | 12.5 miles, last 3.5 miles at half marathon pace |
| 11 | 5 miles easy | 4 x 1500 m long intervals, 2-minute recovery | 8.5 miles, last 2 miles at half marathon pace |
| 12 | 3.5 miles easy with 4 strides | 20 easy minutes with 2 miles at half marathon pace, five days out from the race | Race |
Week twelve cuts volume and keeps a brief touch of race pace, just enough to hold the memory of that rhythm without adding fatigue. In the two days before the race, run twenty easy minutes or skip running entirely.
How to Adjust If You Miss a Week
Missed sessions don’t stack onto the ones that follow. Miss one week, and you repeat the last week you completed, then pick the progression back up where it left off. The race date stays fixed, so one row has to go: drop one of the middle build weeks, three or seven, never the recovery week and never the final two.
With two weeks off, drop back two rows and restart from there, accepting that the block will reach the race with lower mileage. Past three weeks, test pace no longer describes your current fitness, and the right move is to retest before picking things back up: it will almost always come back slower, and every zone needs recalculating from that new number.
When a week gets squeezed and you can only save one session, keep the long run. It’s the least replaceable workout, and the one whose repeated absence you’ll feel most in the closing miles of the race.
Retesting Mid-Block: When It’s Worth It and When It’s Not
The useful window is week nine, after eight weeks of continuous training and before volume peaks. The signal that makes a retest worthwhile is technical: two consecutive quality sessions where the prescribed pace feels clearly comfortable and the final reps come out faster than the first. A 10K race on your calendar can substitute for the test, as long as you run it with the same split management.
For the comparison to mean anything, the retest replicates the first: same course, same time of day, comparable dew point, same shoes. Change any one of those variables, and you can’t tell whether the difference in the number reflects your fitness or your conditions.
Skip it in three cases. The week right after a break, because the number will capture a temporarily diminished fitness and you’ll end up slowing down zones you could actually still hold. In the final three weeks, when an all-out test drains recovery without leaving time to use the data. And when the urge to retest comes from a single bad session, which says something about the day and nothing about your fitness.
If the retest confirms improvement, the new test pace replaces the old one across every zone, including the easy end. Updating only the fast paces and leaving easy pace where it was is the fastest way to turn real progress into chronic fatigue.