Cardio vs. Strength Training: What Each Does for Your Body

What Each Type of Exercise Actually Does

Cardiovascular exercise — any sustained rhythmic movement that raises your heart rate — trains the heart and lungs to deliver oxygen more efficiently. During a brisk walk, jog, or swim, your body relies primarily on aerobic metabolism: oxygen is used to convert fuel into sustained energy. Over time, regular cardio lowers resting heart rate, improves blood pressure, and increases the lungs' ability to exchange oxygen and carbon dioxide. These adaptations reduce the risk of cardiovascular disease, stroke, and type 2 diabetes.

Strength training (also called resistance training) works differently. By applying load to muscles — through weights, resistance bands, or bodyweight — it creates microscopic stress in muscle fibers. The body repairs and reinforces those fibers, building muscle tissue. That increased muscle mass raises your resting metabolic rate (the energy you burn at rest), supports joint stability, and places beneficial stress on bones, stimulating them to become denser. According to the National Institutes of Health, age-related muscle loss (sarcopenia) can begin as early as one's 30s, making strength work a long-term investment for the whole family.

What the Research Says About Combining Both

Major health authorities — including the U.S. Department of Health and Human Services — recommend that most adults get both: at least 150 minutes of moderate-intensity aerobic activity per week and muscle-strengthening activities on two or more days. This isn't coincidental. Research consistently shows that the benefits of cardio and strength training overlap without fully replacing each other.

For example, cardio alone does not sufficiently counter bone loss or preserve lean muscle mass. Strength training alone, without adequate aerobic activity, leaves cardiovascular fitness underserved. When combined, they create a more resilient body — one that performs well, recovers faster, and maintains function longer into older age. Families who see fitness as a shared habit rather than an individual chore tend to find this balance more achievable. For perspective on common assumptions around exercise habits, see our piece on family fitness myths worth questioning.

How Age and Life Stage Shape the Balance

Children and adolescents naturally accumulate a mix of both through play, sports, and structured activity — and that variety matters for healthy development. The CDC recommends that children aged 6–17 get 60 minutes of physical activity daily, including aerobic movement and muscle- and bone-strengthening activities three days per week. Families wondering how teens specifically respond to exercise may find useful context in our article on how teenagers experience exercise differently than adults.

For older adults, the emphasis on strength training grows. Maintaining muscle and bone health becomes more critical, while the risk of falls and fractures rises. Low-impact forms of cardio — walking, cycling, water aerobics — can support heart health while being gentler on joints. Our guide to low-impact exercise options and who they suit covers these in more detail. Individuals with chronic conditions should consult a qualified healthcare professional before changing their exercise routine.

For families weighing where to exercise as well as how, outdoor vs. indoor exercise explores how environment shapes consistency and enjoyment.

This article is for general informational and educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting or changing any exercise programme, particularly if you have an existing health condition.