Introduction
Most of us know that regular exercise is good for our health. It can reduce our risk of developing many chronic diseases and is associated with living a longer life. But there are countless ways to get moving — from running and cycling to weight training, CrossFit and HYROX — and new fitness trends are constantly appearing.
If you have limited time to exercise, what should you prioritise? Is cardio or strength training better for longevity, or do we need both?
Longevity isn't simply about adding more years to your life. It's also about staying healthy and independent during those years. Preventing cardiovascular and metabolic disease matters, but so does maintaining the muscle strength, bone health and physical function that become increasingly important as we age. So, when it comes to building an exercise routine for a longer, healthier life, how do cardio and strength training compare?
How does cardio contribute to my health?
Regular cardiovascular exercise causes your heart and circulatory system to adapt. Your heart becomes more efficient at pumping blood, meaning it can deliver more oxygen around your body with each beat. Exercise also helps your blood vessels remain flexible and able to widen when needed, reducing resistance to blood flow and helping to lower blood pressure. Together, these changes reduce the workload on your heart and can lower your risk of cardiovascular diseases such as heart attacks and strokes.
The benefits go beyond your heart. Cardio improves your body’s sensitivity to insulin, helping to regulate blood sugar and reduce the risk of developing type 2 diabetes. Regular aerobic exercise can also improve your cholesterol profile, including increasing levels of HDL (“good”) cholesterol and lowering triglycerides.
Cardio also increases the amount of energy you use and can therefore help with maintaining a healthy weight. However, its benefits aren’t simply the result of burning calories: improvements in blood pressure, blood sugar control and cardiovascular fitness can occur even without significant weight loss.
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How does strength training contribute to my health?
As we get older, we naturally lose muscle mass and strength. Strength training helps slow this decline by stimulating your muscles to maintain or build muscle tissue. This matters for longevity because maintaining strength helps preserve mobility and independence as we age, while also supporting bone health and reducing the risk of falls and frailty.
The benefits extend beyond your muscles. Muscle is an important site for removing glucose from the bloodstream, so maintaining and building muscle can improve blood sugar control and reduce the risk of type 2 diabetes. Strength training is also associated with better cardiovascular health.
These effects appear to translate into longer life. A systematic review found that people who did any resistance training had a 15% lower risk of death from any cause, a 19% lower risk of cardiovascular death and a 14% lower risk of cancer death compared with those who did none. Interestingly, the greatest reduction in all-cause mortality was observed at around 60 minutes of resistance training per week, with the apparent benefit diminishing at higher volumes. This suggests you don't need to spend hours in the gym to gain meaningful health benefits.
So which wins: cardio or strength?
If we had to choose based purely on the associations seen in mortality data, cardio appears to have the edge — but the evidence suggests that doing both is better than choosing between them.
A large study published in the BMJ followed 479,856 adults and compared people according to whether they met recommended levels of aerobic and strength exercise.
Exercise recommendations met | All-cause mortality risk compared with meeting neither recommendation |
Strength training only | 11% lower |
Aerobic exercise only | 29% lower |
Aerobic + strength training | 40% lower |
The standout finding isn't really that cardio beat strength training. It's that people meeting both recommendations had the lowest mortality risk, suggesting the two forms of exercise may provide complementary benefits.
Importantly, this doesn't mean that combining cardio and strength training will reduce an individual's risk of dying by exactly 40%. This was an observational study, so it can show an association but cannot prove that exercise was responsible for the entire difference.
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So what should your week actually look like?
The good news is that you don't need to spend hours exercising every day to reach the levels associated with better long-term health. Current NHS guidance recommends combining aerobic exercise with regular strength training:
Cardio: Aim for at least 150 minutes of moderate-intensity aerobic exercise each week, such as brisk walking or cycling, or 75 minutes of vigorous exercise, such as running or fast cycling. You can also use a combination of moderate and vigorous exercise.
Strength: Aim to do strengthening exercises that work all the major muscle groups on at least two days each week. This could include lifting weights, using resistance bands or bodyweight exercises such as squats and press-ups.
In practice, this could be as simple as two full-body strength sessions and three 50-minute brisk walks or cycles each week. You can also combine cardio and strength on the same day, so reaching both targets doesn't necessarily mean exercising every day.
These should be viewed as targets rather than an all-or-nothing threshold. If you're currently doing very little exercise, starting with what feels manageable is still worthwhile — you don't need to hit the full recommendation from week one to start becoming more active.
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