Concurrent Training: Can You Run and Lift?

The question comes up every time a strength athlete looks at a pair of running shoes: will cardio kill my gains? The short answer is no. The longer answer — the one that actually matters for programming — is that endurance and resistance training can coexist productively, but the dosage, modality, timing, and sequencing all matter. Get those variables wrong and you will compromise one adaptation or both. Get them right and you build a more complete athlete without sacrificing meaningful strength or muscle mass.

The Hickson Study and Its Long Shadow

In 1980, Robert Hickson published the study that launched four decades of interference effect anxiety. He had untrained subjects perform both strength training and endurance training simultaneously over ten weeks. The concurrent group gained less strength than the strength-only group, particularly in the later weeks when endurance volume was highest. The finding was real, the methodology was solid, and the result has been misinterpreted ever since.

Hickson’s subjects were running and cycling six days per week on top of heavy resistance training five days per week. The total training load was enormous — far beyond what any reasonable concurrent program would prescribe. Extrapolating from that protocol to the claim that “a 20-minute jog will shrink your squat” is the kind of leap that happens when a study title gets more attention than its methods section.

What the Meta-Analyses Actually Show

Wilson and colleagues published the most comprehensive concurrent training meta-analysis in 2012, pooling data from 21 studies. Their findings were more nuanced than the internet discourse suggests.

Hypertrophy interference was minimal. Muscle cross-sectional area and fiber hypertrophy were not significantly impaired by concurrent training in most studies. The body can build muscle while also building aerobic capacity, provided total volume is managed.

Strength interference was modest. Maximal strength gains were slightly reduced in concurrent groups compared to resistance-only groups, but the effect was small and heavily modulated by the type of endurance training performed.

Power was most affected. Explosive power — measured by vertical jump, rate of force development, and similar metrics — showed the most consistent interference. This makes sense physiologically: power development requires maximal motor unit recruitment and fast-twitch fiber adaptation, both of which are compromised by high volumes of slow-oxidative endurance work.

Running produced more interference than cycling. This is the finding that gets the most practical attention. The eccentric loading of running creates muscle damage that competes with recovery from resistance training, particularly in the lower body. Cycling, with its concentric-dominant pattern, imposes less mechanical stress on the muscle and therefore interferes less with hypertrophy and strength signaling.

The Molecular Crosstalk

The interference effect has a molecular basis, though it is less absolute than early models suggested. Resistance training activates the mTOR pathway, which drives muscle protein synthesis. Endurance training activates AMPK, which promotes mitochondrial biogenesis and oxidative capacity. AMPK can inhibit mTOR signaling, theoretically blunting the hypertrophic response to resistance training.

But this inhibition is transient and dose-dependent. A 30-minute moderate-intensity run produces a brief AMPK spike that largely resolves within a few hours. A 90-minute high-intensity interval session produces a more sustained elevation that may genuinely compete with post-resistance-training mTOR activity. The interference is not binary — it scales with the volume and intensity of the endurance stimulus.

Recent research has also challenged the clean separation of these pathways. Some studies show that endurance training can upregulate mTOR signaling in certain contexts, particularly in untrained or moderately trained individuals. The molecular picture is messier than the textbook diagrams suggest, which is actually good news for hybrid athletes — it means the interference is more manageable than the simplified model predicts.

Programming for Minimal Interference

The practical goal is to capture the cardiovascular and health benefits of endurance work while minimizing the compromise to strength and hypertrophy goals. Several programming strategies have emerged from the research.

Separate sessions by at least six hours. If you must run and lift on the same day, put as much time as possible between the two sessions. Morning cardio and evening lifting — or vice versa — allows the acute molecular signaling from each session to resolve before the next stimulus arrives. Training both modalities back-to-back compresses the interference window and amplifies the AMPK-mTOR competition.

Lift first when sessions are combined. If schedule constraints force same-session concurrent training, perform resistance work before endurance work. The post-lifting window is the most critical for mTOR-mediated protein synthesis. Fatiguing the muscle with endurance work before resistance training also degrades lifting performance — you squat less after a 5K than you would fresh.

Cap endurance volume. The Wilson meta-analysis found significant negative relationships between endurance training frequency, duration, and all three strength outcomes (hypertrophy, strength, power). Three endurance sessions per week totaling 90-120 minutes appears to be the threshold below which interference remains minimal for most lifters. Exceeding that — particularly with running — begins to erode strength gains in a dose-dependent manner.

Favor low-impact modalities when possible. Cycling, rowing, and swimming impose less eccentric muscle damage than running. For lifters whose primary goal is strength and who want cardiovascular conditioning as a secondary benefit, these modalities provide a better interference profile. Running remains valuable for athletes who need running-specific fitness, but the recovery cost should be accounted for in program design.

Periodize the emphasis. Rather than maintaining high volumes of both modalities year-round, alternate phases of emphasis. A hypertrophy block might reduce running to two easy 20-minute sessions per week. A running-focused block might reduce lifting to two maintenance-volume sessions. This block-periodized approach — sometimes called conjugate or sequential periodization — allows each quality to receive focused development without chronic interference.

For runners who also lift, VDOT-based race pace estimators help calibrate endurance intensity so that easy runs stay genuinely easy — a common failure point where too-hard aerobic work unnecessarily amplifies the interference signal.

The Practical Reality for Most Lifters

Most recreational strength athletes are not at risk of meaningful interference from moderate cardio. The studies showing significant strength decrements involved high-frequency, high-volume endurance programs layered on top of already demanding resistance protocols. A lifter who adds two or three 30-minute conditioning sessions per week — whether that is cycling, rowing, brisk incline walking, or easy running — is unlikely to see any measurable reduction in strength or hypertrophy.

The greater risk for most lifters is not doing enough cardiovascular work. Aerobic fitness supports recovery between sets, improves work capacity across training sessions, and has profound health benefits that resistance training alone does not fully provide. Resting heart rate, blood pressure, and cardiovascular disease risk all respond to aerobic stimulus in ways that heavy lifting cannot replicate.

Who Needs to Worry

The interference effect becomes genuinely relevant for three populations. Competitive powerlifters in the final weeks of meet preparation should minimize endurance work to maximize neuromuscular readiness. Athletes training for both a marathon and a strength competition simultaneously face a real programming conflict that requires careful periodization. And advanced lifters close to their genetic ceiling for strength may find that even modest endurance volumes blunt the already-small marginal gains available to them.

For everyone else — which is most people reading this — run and lift. Just be thoughtful about how you sequence them, how much total volume you accumulate, and whether your recovery supports both demands. The interference effect is a real physiological phenomenon, but it is a programming problem with known solutions, not a reason to avoid the treadmill entirely.

Jake Torres is the Science Editor at Fitpass Strength. He holds a PhD in Exercise Physiology and has published peer-reviewed research on concurrent training adaptations.