Many runners love to skip leg day. I know from experience, and I’m even someone who loves lifting. As soon as my mileage ramps up, the excuses start flowing: I don’t want heavy legs during speed workouts. A lower-body workout will exhaust me. I’m already struggling with my race-pace kilometres during a long run – wouldn’t leg day just set me back?

…if you programme your leg days correctly, they can boost your training, rather than hinder it.

But if you programme your leg days correctly, they can boost your training, rather than hinder it. The goal of strength workouts during a marathon buildup isn’t to build massive legs or set a PB in your deadlift. It’s to develop (or maintain) enough strength to make running feel easier and to stay injury-free through months of training. Then, when you arrive at the starting line, your muscles will be primed to handle all 42.2 kilometres without crashing.

Here’s how strength and running coaches recommend fitting leg day into marathon training without sacrificing your long run or your speed.

Why Runners Need Leg Day
Logging miles prepares your heart, lungs, and aerobic system for race day. Strength training makes your body better equipped to handle those miles. “If running builds the engine, then strength training is the chassis,” says Kristina Centenari, a certified strength and running coach. The biggest benefits fall into two categories, she says: running economy and durability.

Running economy is how much energy it takes to maintain a given pace. The more economical you are, the less effort each stride requires, and the longer you’ll be able to hold your goal pace before you get tired. Research shows resistance training boosts running economy, and it can improve the amount of force your muscles produce with every step, making each stride more efficient. Combined with speedwork, those gains can lead to faster race times.

Strength training also makes runners more durable. Every stride sends forces up to 2.5 to 3 times your bodyweight through your muscles, tendons, bones, and connective tissue. Multiply that by tens of thousands of steps over the course of a marathon, and it’s easy to see why so many runners struggle with overuse injuries.

Lifting helps your tissues better tolerate that repetitive stress. “Especially when you get to that 32km mark and things just want to break down, that’s where you’re going to see the biggest gains from your strength training,” says Centenari.

Researchers who study durability also call out strength training (particularly heavy lifting and plyometrics) as a method for improving this metric.

How to Lift Without Interfering With Your Running
Ideally, runners would incorporate strength training well before their marathon training officially begins—like in the winter or spring before a fall race (at least). That way, once you start ramping up the mileage, you’ll have a solid base, says Heather Milton, CSCS, clinical exercise physiologist and certified strength and conditioning coach who specialises in working with runners.

By gradually increasing the amount of weight you lift beforehand (a concept known as progressive overload), you’ll be better equipped to maintain strength while running. You’ll also be less likely to deal with the muscle soreness that often comes with starting a lifting programme.

But if you’re already halfway through your training plan, don’t worry. You can still add strength work. Just start conservatively, using fewer exercises, manageable weight, and lower overall volume until your body adapts.

No matter where you’re at in your strength plan, follow these tips to make sure leg day complements your marathon miles.

Scheduling Your Leg Days
Two or three strength training days is often the sweet spot for runners, with only one devoted leg day a week during marathon training. You can split between upper and lower body days, or opt for all full-body sessions. For example, a three-day programme may look like one upper, one lower, and one full-body day. For two days, you’d have an upper and lower day (or two full-body days).

You don’t need to hit the gym for hours, either – 45 minutes is often all you need to fit in exercises for every major muscle group (and even 20 to 30 minutes is great).

Many people lift on one day and run the next day, but if you’re trying to balance both, that doesn’t leave enough time to fully recover. Instead, Centenari suggests completing both your hard runs and strength training (specifically lower-body sessions) on the same day. For example, do your threshold run in the morning, and then a lifting workout that evening. Always run first, as that is your priority during race training, says Centenari. This may seem counterintuitive, but it allows your easy days to actually stay easy, giving your body more complete recovery between hard efforts.

If you’re doing your long runs on the weekends, do all your lifting before Thursday to give yourself a full 48 hours before a long run.

Throughout the training block, your strength programme will evolve. “As your running volume climbs, you want your strength volume to drop but the intensity to stay high,” says Centenari. Then, when you’re at peak mileage for running – four weeks out from race day – she recommends keeping one heavy strength session with only a few exercises and low reps (five to six) to maintain your adaptations. At this point, you’re not trying to create any new strength gains, and you should only do familiar movements without trying to push the weight.

Some coaches recommend cutting strength workouts entirely during your taper weeks. However, Centenari says that’s not necessary as long as you don’t go too hard. “That could literally just be a 15-minute gym session once a week,” she says.

In the week leading up to race day, avoid any eccentric exercises, where you’re moving slowly while the muscle is lengthening (like Nordic hamstring curls). “That actually creates more soreness,” says Centenari. “So I would just stay away from that stuff.”

Choosing Your Exercises
The main focus and foundation of any strength training programme should be a heavy compound lift, like a deadlift or squat. But you should also add in single-leg work, like split squats, step-ups, or single-leg deadlifts. Running is essentially a series of single-leg landings, so unilateral exercises better prepare you for the demands of the sport while helping address side-to-side imbalances.

Don’t neglect your posterior chain, either. “Runners are often super quad dominant, so glute bridges, hamstring curls, and anything that targets the back of the body are really important,” says Centenari.

Finally, spend a few minutes strengthening your calves and feet. Those smaller muscles absorb enormous loads with every step, but they’re often overlooked. “Especially with a lot of beginner runners, that’s where a lot of the injuries start to seep in,” Centenari adds.

Once you’ve built a strength base, Milton recommends adding plyometrics during the second half of your training cycle. Box jumps, pogo hops, and bounds improve your ability to produce force quickly while increasing tendon stiffness.  A 2025 study in Frontiers in Physiology found that combining heavy strength work with explosive movements was more effective at improving running economy than heavy lifting alone.

Aim for about 50 to 100 foot contacts in a session, counting how many times you’re jumping and landing. Anything above that is not necessary, says Milton. “You’re not trying to fatigue yourself with the plyometrics,” says Centenari. “You’re just trying to get springier and more powerful.”

Picking the Right Reps, Sets, and Weight
The most common mistake that runners make is treating leg days as if they’re chasing aesthetic gym goals, using high-rep ranges (10+) and feeling totally gassed by the time they leave the gym. Milton says high-repetition strength training fatigues your muscles in a very similar way to running, so it’s best to avoid it while training for a race. “It’s really that 10 to 12 rep range that people start getting injured because that’s just so much volume on top of your running already,” adds Centenari.

Instead, use low-rep ranges (five to eight) and heavy loads, around 80 percent of your one-rep max. As you perform the exercise, choose a weight where, by the time you hit the rep target, you still have two “reps in reserve,” meaning you could push out about two reps without breaking form, says Milton.

Overall, keep your expectations in check and avoid pushing your limits. “It’s very hard to make gains in strength, especially in lean mass or hypertrophy, while you’re also trying to build endurance,” says Milton. Your goal with strength training should be more about maintaining what you built before and supporting your running with gradual progressions.

This article first appeared on the Runner’s World USA website.

READ MORE ON: strength-training weight training