Guide
How should running after leg day change your plan?
Keep the run easy the day after heavy legs, and put the hard run two or more days after them, when your legs are fresh again. Heavy legs barely touch an easy Zone 2 run, but they cut a hard run short for one to three days.
What the studies show
Heavy lower-body strength work reduces time-to-exhaustion in a hard run, and the neuromuscular fatigue lingers for 24 to 72 hours. An easy Zone 2 run on the same day is barely affected.
So you keep both. You only move the hard run.
Doma & Deakin 2014. Eur J Sport Sci. Acute strength then running six hours later. PMID 24533516
Silva et al. 2022. Sports Med Open. Acute strength-to-running meta-analysis. PMID 35976540
Robineau et al. 2016. J Strength Cond Res. Zero, six and 24 hour recovery spacing trial. PMID 25546450
What to do the day after leg day
- If you squatted or deadlifted heavy yesterday, run easy or ride easy today.
- If the plan says intervals or tempo today, swap it with an easy day and put the hard run on a day with fresh legs.
- If only your upper body was hard yesterday, nothing changes for the run.
An example week
This week passes the next-day rules the app runs, with no day moved. Those rules look back 24 hours, so the earliest day for intervals is two days after heavy legs. If your legs still feel heavy on Wednesday, keep the run easy.
- Monday: heavy legs, 60 minutes.
- Tuesday: easy run, 45 minutes.
- Wednesday: intervals, 50 minutes.
- Thursday: upper body, 60 minutes.
- Friday: easy run, 45 minutes.
- Saturday: long run, 100 minutes.
- Sunday: rest.
- If your intervals are on Saturday, lift legs on Thursday or earlier. Legs on Friday turn the intervals into a tempo run.
- If Monday is your only leg day, Tuesday is an easy run or ride and the intervals wait for Wednesday.
- If you lift upper body the day before intervals, nothing moves.
Where this stops being a rule
The studies show the tired legs and how long they last. The 24 hour look-back and the swap to an easy day are our rule, and no study tests that exact line.
What Loadcast does with this
In the app, the matching rule reads like this.
Your leg day is still in your legs, so no hard intervals today. After heavy squats the running stride stays sluggish into the next day, so intervals lose quality. Easier run today. The hard one comes back with fresh legs.
Every rule with its mechanism is on How Loadcast decides, the studies are on The research behind our content.
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