You can run and strength train in the same program without sacrificing gains in either direction, but the way you structure your week matters more than most people realize. The old belief that endurance work cancels out strength gains has been largely overturned by recent research, which shows that most of the conflict between the two comes down to poor scheduling, excessive volume, or not eating enough to support both.
The Interference Effect Is Real but Manageable
In 1980, a physiologist named Robert Hickson published a landmark study showing that combining endurance and resistance training blunted strength gains compared to lifting alone. This became known as the “interference effect,” and it shaped training advice for decades. But more recent research paints a different picture. A 2024 review in Medicine concluded that a greater number of studies now show concurrent training does not diminish muscle adaptations, and may even enhance muscle growth in some cases.
The interference effect does still show up under specific conditions. Endurance sessions longer than 30 minutes, running frequencies of three or more days per week at moderate-to-high intensity, and short recovery windows between running and lifting all increase the likelihood of blunted strength gains. The takeaway isn’t to avoid combining the two. It’s to be deliberate about how much running volume you stack on top of your lifting, and to build in enough recovery between sessions.
What Happens in Your Muscles
At the cellular level, running and lifting activate competing energy pathways. Endurance exercise flips on a fuel-conservation signal (AMPK) that tells your muscles to prioritize energy replenishment over building new tissue. Strength training does the opposite, activating a growth signal (mTOR) that drives muscle protein synthesis. When you do both back to back, the fuel-conservation signal can partially suppress the growth signal, reducing how much muscle repair and building happens after your lifting session.
This molecular tug-of-war is most pronounced when the two types of exercise happen within a few hours of each other, especially if the endurance bout is long or intense. Separating your running and lifting by at least six hours, or ideally placing them on different days, gives each pathway time to do its job without interference.
Does Exercise Order Matter?
If you have to run and lift on the same day, the question of which to do first comes up constantly. A systematic review on exercise sequencing found that both orders (strength-first and endurance-first) improved endurance performance over time, with only small, inconclusive differences between them. The practical difference is less about long-term adaptation and more about acute performance: lifting heavy before a run can temporarily reduce your running economy due to local muscle fatigue, and a hard run before lifting can cut into the quality of your sets.
The simplest rule is to put whichever goal matters more to you first. Training for a race? Run first. Trying to build strength or muscle? Lift first. If both matter equally, separating them into morning and evening sessions, or different days entirely, sidesteps the problem.
Strength Training Makes You a Better Runner
Beyond the muscle-building question, strength training improves running performance in ways that pure mileage cannot. One study on heavy resistance training found that time to exhaustion during running increased by 12% after a strength program, even though VO2 max (your ceiling for oxygen use) didn’t change. In other words, strength training didn’t make runners more aerobically fit, but it made them more efficient and fatigue-resistant at the same effort level.
The injury picture is more nuanced than many coaches suggest. A large randomized trial of New York City Marathon runners found that a strength training program didn’t significantly reduce overall injury rates compared to a control group. However, among runners who actually stuck with the program (averaging two or more sessions per week), minor injury rates dropped meaningfully: 41.5% reported at least one minor injury, compared to 56.2% of those who didn’t follow through. Consistency, not just intention, was the dividing line. The most common injuries in both groups were knee pain, calf strains, shin splints, IT band syndrome, and Achilles tendinitis.
How Running Type Affects Muscle
Not all running interferes with strength gains equally. A meta-analysis comparing high-intensity interval training to steady-state moderate running found a small, non-significant advantage for intervals when it came to preserving fat-free mass. The effect size was tiny (0.16), so neither type of running is dramatically better or worse for holding onto muscle. But the practical implication is that shorter, more intense running sessions create less total volume and less time under the AMPK signal than long, slow distance work. If preserving muscle is a priority, keeping most of your running sessions under 30 minutes and using intervals for your harder days is a reasonable strategy.
Long runs still have a place, especially if you’re training for a half marathon or longer. Just be aware that these sessions create the most interference with strength adaptations, so schedule your heaviest lifting days as far from your long run as possible.
A Sample Weekly Schedule
A well-structured week for someone balancing both goals might look like this:
- Monday: Light upper-body resistance training
- Tuesday: Tempo run (roughly 20 minutes at a hard but sustainable effort)
- Wednesday: Easy run in the morning, heavy lower-body lifting in the evening
- Thursday: Full rest day
- Friday: Tempo run
- Saturday: Easy run
- Sunday: Long run
This template keeps endurance frequency at about four days per week while fitting in two strength sessions. The rest day after the double session on Wednesday is critical. Notice that the heaviest lower-body lifting is paired with an easy run rather than a tempo or long run, giving your legs the best chance to recover before harder running days. If you want to add a third lifting session, replacing Saturday’s easy run with an upper-body or total-body session works well, since Sunday’s long run primarily taxes your aerobic system rather than requiring fresh legs for speed.
Research suggests that keeping endurance training to about two sessions per week has a lesser impact on strength gains, while three or more sessions per week starts to create more friction. If your main goal is strength and muscle, limit running to two or three shorter sessions and keep the intensity varied.
Fueling for Both
The biggest mistake people make when combining running and lifting isn’t programming. It’s undereating. Both activities increase your protein and carbohydrate needs, and falling short on either will amplify the interference effect because your body lacks the raw materials to adapt to both stimuli.
Current evidence points to a daily protein target of about 1.8 grams per kilogram of body weight for people doing regular endurance work. For a 70-kilogram (154-pound) person, that’s roughly 126 grams per day. During periods when you’re restricting carbohydrates or on rest days, protein needs climb to around 2.0 grams per kilogram. Spreading that intake across meals matters too: aiming for about 0.5 grams per kilogram per meal (roughly 35 grams for that same 154-pound person) maximizes the muscle-repair response, especially in the meal right after training.
Carbohydrate needs are substantial. The studies underpinning these protein recommendations had athletes eating 6 to 8 grams of carbohydrates per kilogram of body weight per day. That’s 420 to 560 grams for a 70-kilogram person. You may not need the top end of that range unless you’re running high mileage, but chronically low carbohydrate intake will hurt both your running performance and your ability to recover from lifting sessions. If you can’t tolerate a large meal immediately after exercise, prioritizing protein in that window (around 0.4 grams per kilogram) still supports glycogen replenishment alongside muscle repair.
Practical Priorities
Balancing running and strength training comes down to a few controllable variables. Separate hard sessions by at least six hours, or better yet, by a full day. Keep your total endurance volume reasonable: sessions under 30 minutes create less interference than long, grinding efforts. Prioritize your primary goal in each session by doing it first when you’re fresh. Eat enough protein and carbohydrates to support both types of training, because underfeeding is where most concurrent training plans quietly fall apart.
Two to three strength sessions per week is the sweet spot for most runners. Two is enough to build meaningful strength and resilience. Three allows more targeted work on upper body, lower body, and core across the week. Beyond three, you’ll likely start cutting into recovery for your running, especially if you’re also running four or more days per week.