An advanced half marathon training plan centers on two things: raising the pace you can hold near threshold, and building a long run that makes 13.1 miles feel routine. Half marathon pace sits just below threshold for most trained runners, so sub-threshold and threshold sessions do most of the work, with steady and marathon-pace running underneath and 10K-pace work on top. Fueling matters more the closer your finish time gets to 90 minutes and beyond.
This guide is part of our running training plans by event series.
What does the half marathon demand?
The race lasts roughly an hour to an hour and a half for advanced runners, almost all of it aerobic. Three qualities decide it:
- Sustained pace: how close to threshold you can run for 60 to 90 minutes without drifting into a pace that collapses.
- Durability: whether your legs and form still work in the last 5K.
- Fuel: enough stored carbohydrate to finish strong, plus a race plan for anything longer than about an hour.
Studies of world-class distance runners show they keep at least 80 percent of their running at low intensity all year, and that race-pace running increases as the main race gets closer. That pattern holds for advanced amateurs: easy days stay easy so the threshold sessions and long runs land well. See the 80/20 rule.
Why is threshold the backbone of the plan?
Half marathon pace is a threshold problem. The goal is to accumulate a lot of time near that line at a cost you can repeat week after week.
- Start below the line: 5 x 6 minutes or 4 x 2K just under threshold effort with short jogs.
- Extend, then sharpen: 3 x 3K, then 2 x 5K, then 20 to 30 minutes continuous at threshold effort.
- Add half-marathon-specific work: 3 x 4K at half pace with 2 minutes jog, or alternations switching between half pace and steady.
- Keep speed in: hill sprints or strides once or twice a week so the threshold diet does not leave you one-paced.
Judge threshold by breathing and control, not one fixed number. See threshold run pace and why lactate threshold is a range.
How should the long run change across the build?
First build a comfortable distance, then put controlled work inside it. A progression long run or one with blocks at half pace is a hard day, not a recovery day, so it needs easy days around it.
- Early: 90 to 120 minutes easy, depending on history.
- Middle: easy long runs with the last 20 to 30 minutes at steady or marathon effort.
- Late: 2 x 4 to 5K at half pace inside a long run, every second week.
See long run percentage of weekly mileage for why duration should come from the event and the runner, not a fixed percentage.
How should you fuel a 60 to 90+ minute race?
Carbohydrate guidance scales with race length. A review of carbohydrate intake during exercise concluded that for efforts around an hour, a mouth rinse or small amounts of carbohydrate can help, while efforts of two to three hours call for up to about 60 grams per hour. A nutrition review for distance runners described the same range, from small amounts or rinsing in shorter races up to 75 to 90 grams per hour in the longest events, and stressed that a race plan should be personalized and practiced.
What that means in practice:
- Under about 70 minutes: eat a normal carbohydrate-rich meal in the day before and a familiar breakfast. A gel just before the start or a sports drink sip is optional.
- 75 to 90 minutes: one gel around 30 to 40 minutes, a second around 60 minutes if you tolerate it.
- Over 90 minutes: plan carbohydrate across the race, roughly 30 to 60 grams per hour, and rehearse it in long runs.
- Fluids: drink to thirst. Do not overdrink. See when runners need fuel.
Never try a new gel, drink or caffeine dose on race day.
What does a sample week look like in each phase?
Paces come from current fitness: easy, steady, marathon, half, threshold, 10K. If your current half is 1:18, targets follow from 1:18 and update as you improve.
Base (about 6 to 8 weeks)
- Mon: easy, strides.
- Tue: steady run, 40 to 50 minutes.
- Wed: easy, strength.
- Thu: sub-threshold reps, such as 5 x 6 minutes with 1 minute jog.
- Fri: easy or off.
- Sat: easy plus 6 to 8 hill sprints.
- Sun: easy long run.
Threshold (about 5 to 6 weeks)
- Tue: threshold reps, extending total time.
- Fri: alternations or 4 x 1 mile with an 800m steady float.
- Sun: long run with a steady finish.
- Easy days genuinely easy, strides twice a week.
Specific (about 4 weeks)
- Tue: half-pace work, such as 3 x 4K with 2 minutes, building to 2 x 6K.
- Fri: 10K-pace reps or a combo session (threshold then 4 x 1K at 10K pace).
- Sun: long run with half-pace blocks every second week.
- One tune-up race, a 10K or 10 miles, to practice pacing and fueling.
How long should the taper be?
Between a 10K and a marathon taper: about 10 to 14 days. A meta-analysis of tapering found the largest gains when volume fell by roughly 40 to 60 percent over about two weeks while intensity and frequency held. Keep your running days, cut volume, and keep one short session at half pace early in race week plus strides.
How should you pace a half marathon?
Run the first 5K at goal pace or a few seconds per mile slower, not faster. Settle into a group if you can, hold steady effort through 15K, and think of 15K to 18K as the hard middle: chunk it into the next mile marker. Race the last 3K. On hills, hold effort rather than pace.
How your HealthAI coach applies this
Your coach sets threshold, half-pace and long-run targets from your current fitness and adjusts them from the runs you log in the health portal. It writes two weeks at a time and includes a fueling note on any session over 75 minutes. If your check-ins show short sleep, heavy legs or low energy, it moves or shortens the next hard day. Plans start at $30 a month; see plans.
Your coach builds this around your training data. Start at HealthAI.coach.
Sources
- Haugen T et al., The Training Characteristics of World-Class Distance Runners: An Integration of Scientific Literature and Results-Proven Practice. Sports Medicine Open, 2022. doi:10.1186/s40798-022-00438-7
- Jeukendrup A, A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 2014. doi:10.1007/s40279-014-0148-z
- Burke LM et al., Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers. International Journal of Sport Nutrition and Exercise Metabolism, 2019. doi:10.1123/ijsnem.2019-0004
- Bosquet L et al., Effects of tapering on performance: a meta-analysis. Medicine and Science in Sports and Exercise, 2007. doi:10.1249/mss.0b013e31806010e0