Strength Training Versus Cardio: What the Research Actually Says

What Each Type of Exercise Actually Does

Strength training — also called resistance training — uses muscular effort against an external load to stimulate adaptation. That load can come from free weights, machines, bands, or even bodyweight. Over time, the body responds by building or preserving muscle tissue, reinforcing connective tissue, and increasing bone density. If you're curious about how bodyweight methods compare with weighted tools, our article on bodyweight versus weight training goes deeper on that distinction.

Cardio — short for cardiovascular exercise — places sustained demand on the heart, lungs, and circulatory system. Running, cycling, swimming, and brisk walking all qualify. The body adapts by improving the heart's pumping efficiency, increasing lung capacity, and enhancing the muscles' ability to use oxygen. One well-studied form, zone 2 training, is especially effective for building aerobic capacity; see our guide on zone 2 cardio for a full breakdown.

What the Research Reveals About Health Outcomes

The evidence base for both modalities is substantial, but it points to distinct advantages rather than one clear winner.

Cardiovascular health: Aerobic exercise has the most consistent research support for reducing cardiovascular disease risk. It lowers resting blood pressure, improves cholesterol profiles, and reduces inflammatory markers associated with heart disease. Strength training contributes too, but its cardiovascular effects are generally smaller in magnitude.

Body composition: Resistance training is uniquely effective at increasing lean mass and resting metabolic rate — the calories your body burns at rest. Cardio burns more calories during the session itself but contributes less to long-term metabolic adaptation.

Bone health: Weight-bearing resistance training is among the most evidence-backed interventions for preserving and building bone mineral density, particularly relevant for adults over 50. Our overview of fitness after 50 covers this in practical terms.

Longevity: A growing body of research associates both types of exercise with reduced all-cause mortality. Some analyses suggest that combining strength and cardio training yields greater longevity benefits than either alone.

Building a Routine That Uses Both

Most major health organizations — including the U.S. Department of Health and Human Services — recommend adults get both aerobic activity and muscle-strengthening activity each week. The practical question is how to fit both in without overtraining or burning out.

Frequency depends heavily on your current fitness level, recovery capacity, and goals. Our evidence-based look at how often you should work out can help you find a realistic starting point. Most people can make meaningful progress with two to three sessions of each type per week, though how you divide them across days is flexible.

If joint discomfort is a factor, cardio doesn't have to mean high-impact options. Swimming, cycling, and elliptical training offer aerobic benefits with far less stress on knees and hips. Our guide to low-impact exercise options explores these alternatives in detail.

This article is for general informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before beginning any new exercise program, especially if you have an existing health condition or injury.