Guide
How do you train for a half marathon and still go to the gym?
Keep lifting through the build, because it makes you more economical and does not reduce your VO2 max, and keep heavy legs away from the day after your long run. With a race date set, Loadcast keeps lifting at full effort early, cuts it to maintenance in the race-specific weeks and takes it out 28 days before the race.
Last updated: 2026-10-16
By Ole Fiegenbaum, founder of Loadcast. Before the app, Ole's triathlon training ran through one ChatGPT chat. More on the landing page.
How this page was made: the rules and example weeks come from the Loadcast engine, and every example week runs through the same check as the app. The studies are linked. The text was written with AI help.
Keep lifting through the build
Lifting makes runners more economical and does not reduce VO2 max or blood lactate. This is why a half marathon build keeps the gym days instead of dropping them.
The cost sits on the lifting side. In Wilson and colleagues (2012), running on top of lifting showed clear losses in size and strength against lifting alone, and Coffey and Hawley think this is likely down to the heavier eccentric load and muscle damage of running. If you have lifted for years and start a half marathon build, strength is the quality at risk. That is our reading, not a result from one paper.
Blagrove et al. 2018. Sports Med. Strength training and middle and long-distance running performance, systematic review. DOI 10.1007/s40279-017-0835-7
Wilson et al. 2012. J Strength Cond Res. Concurrent training meta-analysis. PMID 22002517
Coffey & Hawley 2017. J Physiol. The molecular basis of concurrent training. PMC5407958
The long run sets your leg day
A long run blunts heavy leg strength for a day or two. Heavy leg work on top of it slows both the lift and your recovery.
In Loadcast, an easy or long run of 75 minutes or more counts as a long run, and a little less if you are older. A tempo or interval run does not. The day after it, heavy legs are swapped for upper body.
- If your long run is Sunday, Monday is upper body or an easy day, never heavy legs.
- If your long run is Saturday, heavy legs move from Sunday to Tuesday, Wednesday or Thursday.
Škof & Strojnik 2006. Br J Sports Med. Neuromuscular fatigue after prolonged running at anaerobic threshold. PMC2491987
What changes by phase
With a race date set as your main goal, Loadcast splits the weeks before the half marathon into phases and counts back from race day. The long run grows from phase to phase, and lifting leaves the plan 28 days out. Minutes are the long run Loadcast aims for in that phase, not week one: it grows by at most 15 percent over your longest recent run. A slower easy pace lifts the minutes a little, up to a ceiling for the phase.
In the taper and in race week there is no long run in the plan. Lifting already left the plan in the peak, 28 days out. From 14 days out, a lifting day becomes an easy run.
The race-specific build is 45 percent of your build weeks, at most 8 weeks, and it does not exist for a build shorter than 2 weeks.
| Phase | Days to race | Lifting | Long run |
|---|---|---|---|
| Early build | Before the race-specific build | Full effort | 75 minutes |
| Race-specific build | Up to 8 weeks, ending day 29 | Maintenance, moderate effort | 95 minutes |
| Peak | 28 to 15 | None | 110 minutes |
| Taper | 14 to 8 | None | No long run |
| Race week | 7 to race day | None | No long run |
An example week
This week has two lifts and passes the next-day rules the app runs, with no day moved. The long run is 100 minutes, between the 95 and 110 minutes of the last two build phases.
Monday: upper body, 60 minutes.
Tuesday: intervals, 50 minutes.
Wednesday: easy run, 45 minutes.
Thursday: heavy legs, 60 minutes.
Friday: rest.
Saturday: easy run, 45 minutes.
Sunday: long run, 100 minutes.
What these lines do not know
The studies compare people who lift and run over weeks, and none of them follows a half marathon build. The 75 minute line, the phase lengths and the long run minutes are Loadcast rules, not results from a study. Taking lifting out of the last 28 days is our rule too.
Two lifts a week is the example here. No study tells you the right number for your build.
What Loadcast does with this
In the app, the matching rule reads like this.
Your long run is still in your legs, so no heavy leg work today. A long run tires the legs into the next day. Heavy leg work on top slows both strength and recovery. Upper body or easy today. Legs get their strength day once they have recovered.
Every rule with its mechanism is on How Loadcast decides, the studies are on The research behind our content.
More guides
Compare apps
Check your own week
Pick what you train each day and see which day breaks your week, and why. Free, no sign-up.
Loadcast is an iPhone app. See it in the App Store.