How to combine strength training and running in one week

You can combine strength training and running in the same week, and the gym work will most likely make you a more economical runner (Blagrove 2018). If you place the sessions badly, the cost shows up in the workouts themselves: intervals that feel flat, squat sets you cut short. So the useful question is which day gets what.

What strength training does for your running

Running economy is the energy you need per kilometer at a given pace. Lower is better, because the same pace then costs you less.

A systematic review of 24 studies looked at strength training in middle- and long-distance runners. In most of them, running economy improved by 2 to 8 percent compared with a control group, while maximal oxygen uptake and body mass didn't change (Blagrove 2018). The type of lifting matters. Heavy or explosive strength training is what improves economy, and it does so without weakening endurance (Rønnestad 2014). Stiffer tendons and more fatigue-resistant muscle fibers are the likely mechanisms (Rønnestad 2014).

The body mass result speaks to a common worry about running and lifting. At the doses used in those studies, the runners didn't get heavier (Blagrove 2018).

What running does to your strength

Less than its reputation suggests. A meta-analysis of 43 studies found that adding endurance training doesn't measurably blunt maximal strength or muscle growth in healthy adults (Schumann 2022). Explosive strength was the exception, and it suffered mainly when both were trained in the same session (Schumann 2022). Another review came to a similar conclusion: at a moderate dose with enough spacing, there's little evidence that endurance work holds back muscle growth, and interference shows up mainly with high volume and too little recovery (Murach 2016).

Running is still the tougher partner for a lifter. In an older meta-analysis of 21 studies, losses in strength and muscle growth got larger the more often and the longer people did endurance work, and running interfered with strength gains more than cycling did, probably because it loads the legs harder (Wilson 2012).

The day decides most of it

In the hours after a session, the molecular signals from a strength stimulus and an endurance stimulus compete, and how exactly that turns into interference is still unresolved (Coffey 2017). In practice that leaves you two levers to work with.

The first is order within a day. Run first and the lifting pays: after an endurance session, the volume of work in a following strength session was reduced for up to eight hours (Sporer 2003). Lifting first moves the cost to the run. A single strength session, especially for the legs, lowers the quality of endurance work in the hours to days that follow, through worse running economy and sore legs that are short on glycogen (Doma 2017).

The second is spacing. From a run to a strength session, 24 hours was enough for strength volume to hold (Sporer 2003). The other direction needs more care. When lifting and running shared a day six hours apart, running economy the next day was worse if the lifting came first, and running performance dropped after both orders (Doma 2013).

That makes the sorting fairly simple. Upper body and running share a day well, since the legs that run didn't do the heavy work (Doma 2017). From coaching experience, easy pairs with easy: a short easy run and a moderate gym session rarely get in each other's way. Leg day and running hard on consecutive days is the pairing to avoid, especially with the legs first (Doma 2013). For more on spacing two demanding sessions, read our piece on recovery between two hard sessions.

Two sample weeks

Both weeks keep the hard runs (intervals and the long run) at least a day away from the leg session.

Three runs and two strength sessions:

• Monday is the heavy leg session in the gym.
• Tuesday is a short, easy run.
• Wednesday brings the interval session, a full day after the squats.
• Thursday is an upper-body strength session.
• Friday is a rest day.
• Saturday is the long run.
• Sunday is a rest day.

Four runs and two strength sessions, with one double day:

• Monday is the heavy leg session.
• Tuesday is a short, easy run.
• Wednesday brings the interval session.
• Thursday is the double day, with upper body in the morning and an easy run in the evening.
• Friday is a rest day.
• Saturday is the long run.
• Sunday is a rest day.

Thursday's double day works because the morning session leaves the running legs alone and the evening run stays easy. Tahto builds weeks like these around the days you actually have, with your gym sessions and your runs in one plan and the long run on the days you choose.

Which side gets priority

When you combine strength training and running with a race on the calendar, your running plan sets the week. Fix the intervals and the long run first, then place the strength sessions around them, with the leg day well away from the hardest run. If getting stronger matters more, your gym training plan comes first: the leg days stay where they are, and the runs around them stay easy.

In both cases most of your running can be easy. Well-trained endurance athletes spend roughly 80 percent of their sessions easy and roughly 20 percent hard (Seiler 2010). For the intervals you keep, the pace comes from your threshold, and our guide to finding your threshold pace shows how to set it. How strength and endurance fit together beyond this one pairing is the subject of our article on hybrid training.