Can Strength Training Replace Cardio? A Look Into The Research

You've just finished a brutal set of squats. Your heart is hammering, you're dripping sweat, and your lungs are burning. It feels exactly like a cardio workout, so why would you need to hop on the treadmill afterward? 

It's one of the most common questions in the fitness world, and honestly, it makes total sense to ask it.

At a glance, lifting and cardio can feel similar in terms of movement, effort, and intensity. But the physiological stress they create is distinct.

When you go for a run, hop on a bike, or take a brisk incline walk, your muscles need a continuous supply of oxygen. Your heart responds by pumping more blood per minute. Your lungs increase oxygen exchange. Your blood vessels dilate to improve flow. This demand is steady and sustained.

VO2 max, in particular, is one of the strongest predictors of longevity we have. Higher cardiorespiratory fitness is consistently linked to lower risk of cardiovascular disease and all-cause mortality.

Resistance training creates a different stimulus.

When you lift a heavy weight, effort is intense but brief. Muscles contract forcefully, temporarily compressing blood vessels. Blood pressure spikes during the lift. Your heart rate rises, but often in short bursts, followed by rest between sets.

Instead of a sustained oxygen demand, you’re creating intermittent stress. Much of the energy used during heavy lifting comes from anaerobic systems, meaning they don’t rely primarily on oxygen.

This is where the misconception tends to take hold.

Heart rate is an easy metric to see and track. When it spikes during lifting, it feels like proof that you’re doing cardio.

But heart rate alone doesn’t tell the whole story.

During aerobic exercise, your heart rate stays elevated for an extended period, often 20, 30, or 45 minutes continuously. That sustained elevation forces your heart to adapt by becoming more efficient at pumping blood. It also trains your muscles to extract and utilize oxygen more effectively.

During strength training, heart rate typically rises during a set and drops during rest. Even in circuit-style workouts, the cumulative time spent at a steady aerobic threshold is often lower than during a dedicated cardio session.

In other words, the pattern of stress matters just as much as the intensity.

Research comparing resistance training to aerobic training consistently shows that while both improve overall health markers, aerobic exercise produces greater improvements2 in VO2 max and cardiorespiratory endurance.

Before you feel defensive about your lifting routine, let's be clear: resistance training is excellent for cardiovascular health. It just works through different mechanisms than you might expect.

For one, lifting is particularly effective at improving insulin sensitivity. Skeletal muscle is a major site of glucose storage. When you build muscle, you increase your body’s capacity to handle blood sugar efficiently, reducing metabolic strain and lowering risk for type 2 diabetes and heart disease.

Resistance training is also associated with reductions in resting blood pressure over time. While blood pressure may spike during a lift, chronic adaptations can improve vascular function and reduce baseline readings.

And from a structural perspective, strength training challenges the heart in a pressure-based way. Aerobic exercise primarily increases the size of the left ventricular chamber, allowing it to pump more blood per beat. Resistance training, on the other hand, can thicken the heart wall in response to high-pressure demands. These are different adaptations, but both are useful.

Plus, of course, lifting builds and preserves lean mass. Muscle mass supports metabolic health, improves body composition, and enhances long-term resilience—all protective factors for cardiovascular health.

So what does an optimal, science-backed weekly routine look like? The good news is that the research gives us pretty clear guidance here, and it doesn't require spending your entire life in the gym.

The general target to aim for is about 150 minutes of moderate cardio per week (or 75 minutes if you're going harder), plus two or more days of strength training. That's the benchmark most major health organizations agree on, and it sounds like more than it is when you spread it across seven days.

If you want to be more intentional about intensity, try Zone 2 training, a pace where you can hold a conversation but can feel your breathing. It sounds easy, but this moderate intensity is especially effective for building your aerobic base over time. Two or three 30-minute sessions a week is enough to move the needle.

Doing both really does make a difference. People who combine regular strength training and cardio consistently show a lower risk of heart disease and early death than those who do only one. The effects aren't just additive—they're synergistic. Each fills in the gaps the other leaves behind.

Pressed for time? Stack them. Strength first while you're fresh, then 20–30 minutes of cardio at the end. It's not the most optimized approach, but it works. And sustainability always beats the perfect plan you can't maintain.

Strength training absolutely benefits your heart. It lowers cardiometabolic risk, improves insulin sensitivity, and supports healthy blood pressure.

But it doesn’t fully replace the unique adaptations that come from sustained aerobic exercise, particularly improvements in VO2 max and cardiorespiratory endurance, two powerful markers of longevity.

If you care about building muscle, lifting is non-negotiable. If you care about maximizing heart health and lifespan, cardio deserves a seat at the table, too.