Weight training for runners: heavy, light, or not at all?

Weight training for runners comes down to one question most runners get backwards: heavy or light? The instinct says light weights and lots of reps, "for endurance". The research says heavy, or at least heavy enough, with some explosive work on the side. And "not at all" is the option with the weakest case.

This post covers runners' weight training from the loading side: how heavy, how many reps, how many sets, and how the answer changes when you're training for a marathon. The training itself works best when your lifting and running are planned together, by hand or with an app that adjusts your runs to how you recovered.

Heavy vs light: the short answer

Lift heavy enough that the last couple of reps of each set are genuinely hard, in the range of roughly three to eight reps. Add a few jumps. Skip the 20-rep "toning" circuits. If you want that turned into sessions, a twice-a-week strength plan for runners sets it out week by week.

That's the loading question. The bigger case for why runners should lift at all, and where lifting fits in a running week, is covered in the hub.

What the research says about heavy weight training for runners

Heavy loads improve economy and performance

The cleanest example is Støren et al. (2008). Well-trained runners added half squats, four sets of four-rep maxes, three times a week for eight weeks. Running economy improved by 5.0%, time to exhaustion at maximal aerobic speed by 21.3%, and there was no change in VO2max or body weight. Four sets of four. One exercise.

A 2024 meta-analysis of strength methods in middle- and long-distance runners (Llanos-Lagos et al., 2024) defined high-load training as 80% of a one-rep max or more. High-load training had a moderate effect on running performance (time trials and time to exhaustion), combining two or more methods had a large effect, and plyometric training alone wasn't significant. None of the methods changed VO2max.

A companion meta-analysis from the same group on running economy (Llanos-Lagos et al., 2024) found high-load and combined methods improved economy, plyometrics helped at slower speeds, and submaximal loads (40–79% of max) and isometric training didn't beat controls.

Light, high-rep work isn't useless. It's just weaker.

Mikkola et al. (2011) split recreational runners into heavy, explosive and muscle-endurance groups for eight weeks. All three improved maximal endurance running performance. Only the heavy and explosive groups improved maximal strength and leg muscle activation, and only the heavy group improved maximal speed in an anaerobic running test and jump height.

So light circuits won't hurt you. They just leave the most useful adaptations on the table, and you already have a high-rep endurance stimulus. It's called running.

Heavy or explosive both work for economy

Rønnestad and Mujika (2014) reviewed strength training for runners and cyclists and concluded that running economy improves with either heavy or explosive strength training added to endurance work. That's why the practical answer is "heavy, plus some jumps", not one or the other.

Will heavy lifting make me bulky?

Not on two sessions a week alongside running. Støren's runners didn't gain weight. Beattie et al. (2017) ran a 40-week strength program with competitive distance runners and found improvements in maximal and reactive strength, running economy and speed at VO2max, with no significant changes in body mass, fat mass or lean mass.

Building meaningful muscle takes a lot of volume, a calorie surplus and no running mileage competing for recovery. Runners lifting twice a week have none of the three.

How heavy is heavy for a runner?

Heavy is relative to you, not to the person next to you. Use reps in reserve rather than percentages, because most runners don't know their one-rep max and shouldn't test it in the middle of a training block.

If you're new to lifting, "heavy" starts as "learn the movement". Spend a few weeks on squat, hinge, push, pull, carry with moderate loads before you chase low reps. For new runners, the first job is simpler still: beginner core strength training and bodyweight basics before barbells.

Which movements to load is its own question. The ranked list of runner-specific strength exercises covers that, including the ones to skip.

How many sets?

Fewer than you think. Two to four hard sets per main exercise, three or four exercises, done twice a week. That's enough to get stronger without leaving you flat for tomorrow's run. The general rules on how many sets per workout apply, but runners sit at the low end because the running already eats most of the recovery budget.

A weight training plan for runners

Here's a simple two-session weight training plan for runners in a base phase. Each session is about 40–50 minutes.

Add load when every set feels a notch too easy at the top of the rep range.

A weight training schedule for runners

Lifting goes on hard days, not easy ones. Lift heavy on the same day as a quality run (run first, lift a few hours later) or the day after it, and never the day before a key session or long run.

That's a full weight training schedule for runners: two lifts, three quality runs, nothing heavy before the long run.

Weight training for marathon runners

Marathoners are the runners most tempted to drop lifting, because the long run takes over the week. Don't drop it. Shrink it.

• ›Base phase: two sessions, full plan above. This is when strength actually goes up.
• ›Build phase: keep the weights heavy, drop a set from each exercise. Strength holds on less volume than it took to build.
• ›Peak and taper: one short session a week, or two very short ones. Same heavy feel, a third of the volume, nothing new.
• ›Long run weeks: the lift goes early in the week, as far from the long run as possible.

Here's a marathon strength workout explained in one line: squat or deadlift, one single-leg lift, calves, a few jumps, done in 30 minutes, low reps, nothing to failure.

The bigger picture of how to train to run a marathon with the gym still in it has its own guide. And if you're training for a marathon in 6 months, the extra runway is a gift: spend the first couple of months building strength while the running is still mostly easy.

Not at all?

The case for skipping weights is mostly about time. If you truly have three hours a week, running should get most of them. But even one short heavy session a week keeps you in the game, and the studies above improved running economy with surprisingly little lifting: Støren's runners did one exercise. Of the three options, "not at all" is the one with nothing going for it except the time it saves.

How exrsz handles it

exrsz builds a periodized plan from your goal, schedule, level and equipment, with weight training placed around your runs instead of on top of them. It shifts lifting from building to maintaining as your race gets closer, adapts each week to how you actually trained, and reshuffles missed sessions so a skipped lift doesn't land the day before your long run.

FAQ

Should runners lift heavy or light weights?

Heavy enough that sets of three to eight reps are genuinely hard, plus some explosive jumps. A 2024 meta-analysis found high-load training improved running economy while submaximal-load training didn't beat controls.

Will weight training make runners bulky?

Not with two sessions a week alongside running. A 40-week study of distance runners found improved strength and running economy with no significant change in body mass or lean mass.

How often should runners do weight training?

Twice a week in base phases, dropping to once or twice shorter sessions in the build and taper. Put lifting on hard run days or the day after, never the day before a key run.

Is weight training good for marathon runners?

Yes, as long as it shrinks as the race gets closer. Keep the loads heavy, cut the volume in the build, and keep the session well away from the long run.

What's a good weight training plan for runners?

Two sessions a week: one squat-focused and one hinge-focused, each with a single-leg lift, calf raises, an upper-body exercise and a few jumps. Three to six reps on the main lifts with a couple of reps left in the tank.