Strength Training Alone Won't Protect Your Heart, Study Finds

After a full year of lifting weights three times a week, under supervised gym conditions, 406 adults had noticeably stronger muscles. Their hearts, measured across a comprehensive set of cardiovascular risk markers, looked almost identical to people who had done no exercise at all.

That finding comes from the CardioRACE trial, a large randomized controlled trial published in the European Heart Journal in 2024. It compared three types of structured exercise against a no-exercise control group over 12 months, and its results push back directly on one of the most popular health narratives of the last decade: that lifting weights is a meaningful intervention for heart health on its own.

What the Trial Actually Did

The CardioRACE researchers enrolled 406 inactive adults aged 35 to 70 years, all with overweight or obesity and elevated blood pressure. Their cardiovascular risk profile at the start of the study reflected years of inactivity. Participants were randomly assigned to one of four groups: resistance training only, aerobic training only, combined aerobic and resistance training, or no exercise at all. Every session was supervised, lasted a full hour, and took place three times per week for 12 months. Training time was matched across groups, so the comparison was genuinely fair. After a year, everyone was reassessed across a composite measure of cardiovascular disease risk factors, including blood pressure, cholesterol levels, blood glucose, and body fat metrics.

The Result Nobody in the Weights Community Wants to Hear

Aerobic training improved the composite cardiovascular risk profile compared to the control group. Combined aerobic and resistance training also improved it. Resistance training alone did not. On the composite measure, the group that spent a full year doing only strength work three times per week was statistically indistinguishable from the group that sat on their couch.

This is a hard finding to sit with. The resistance training community has spent years, with good reason, pushing back against the cardio-only culture that dominated fitness advice for decades. Strength training does have real health benefits. It improves insulin sensitivity, preserves muscle mass, reduces injury risk, and appears in observational data linked to lower all-cause mortality. None of that is wrong. But the CardioRACE trial, with its controlled design and year-long timeline, draws a specific line: if reducing cardiovascular risk is the goal, aerobic exercise is doing work that resistance training alone is not replicating.

Why Cardio Keeps Showing Up as the Heart Variable

The mechanistic picture has a few well-supported pieces. Sustained aerobic effort trains the heart as a pump, improves how efficiently the body uses oxygen, lowers resting heart rate, and produces consistent blood pressure reductions over time. It also reduces visceral fat more reliably than resistance training, and visceral fat is one of the strongest individual drivers of elevated cardiovascular risk. Resistance training builds contractile tissue and metabolic capacity, but those adaptations are simply different from what the heart and vascular system most respond to.

The combined training group in CardioRACE improved their cardiovascular risk profile. You do not have to pick one form of exercise and abandon the other. But the data is clear that if you are relying on the gym alone, the specific physiological adaptation your heart needs most is probably not happening.

What to Do With This

The most direct takeaway is not to abandon the weights. It is to treat aerobic exercise as non-negotiable if cardiovascular health matters to you, rather than something you bolt on after your sets when there is time. That might look like two or three sessions per week of sustained moderate effort: a 30-minute brisk walk at a pace that keeps your heart rate elevated, a cycling session, a swim. The format matters far less than the consistency and the accumulated time. The CardioRACE participants trained for a full hour, three times per week, across an entire year. Real adaptations in cardiovascular risk markers are earned slowly.

The second implication is for people who exclusively weight-train and count that as covering their health bases. Gym culture has done a good job selling the health narrative around lifting, and much of it holds up. But "I go to the gym" and "I am actively protecting my cardiovascular health" are not the same sentence unless there is something aerobic in the weekly routine.

Your heart is a muscle too. Unlike your biceps, it does not respond most to load. It responds most to time under sustained demand. How much of your weekly exercise actually gives it that?

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References

The CardioRACE Trial Research Group. (2024). Aerobic, resistance, or combined exercise training and cardiovascular risk profile in overweight or obese adults: the CardioRACE trial. European Heart Journal, 45(13), 1127–1138. https://doi.org/10.1093/eurheartj/ehad827