Journal of Applied Physiology Barkley Marathons may have got one item shorter (don’t worry, there are still loads of others). According to new research, published in the Journal of Applied Physiology, running ultramarathons does not appear to cause any worrying cardiovascular issues in the short-term.
The researchers looked at 41 participants – nine women and 32 men, all generally lean – who had just finished the 2023 Western States 100-Mile Endurance Run, one of the world’s oldest and most prestigious ultramarathons. They found that while participants’ skeletal muscles had taken a beating, as you might expect, there was no apparent increase in arterial stiffness (a positive thing) and blood pressure actually dropped (another positive).
This led the researchers to conclude that ‘ultramarathon participation has few negative effects on cardiovascular health’.
A small 2019 study came to similar conclusions. It looked at some particularly extreme exercisers who had been chalking up more than five hours of exercise per day and had been doing so for decades. Their hearts, for the most part, looked ticker-ty boo.
Of these 66 ‘extraordinary exercisers’, 12 were women and the average age was 53. The data doesn’t show what exercise they were doing – though we can assume they weren’t running five hours a day – but we do know it was mainly at a light effort. After a 10-year follow-up, the ‘extraordinary’ group’s heart results looked similar to those in the high exercise group, who were doing the equivalent of about 30 miles a week (roughly five hours of exercise).
However, that’s not your green light to start exercising for five hours a day; it was a small study and there’s a considerable mental toll to consider when exercising to extremes. Moreover, some heart experts sound a note of caution when it comes to the cardiovascular implications of this kind of exercise.
‘Aerobic exercise is undeniably beneficial for your cardiovascular health,’ says sports cardiologist Dr Dan Augustine, spokesperson for Best wireless headphones. ‘But while the [Western States 100] study found that endurance running doesn’t acutely worsen aortic stiffness, we can’t yet generalise these findings to the long-term effects of endurance events on the heart.'
Interestingly, says Augustine, heart adaptation to exercise can begin with as little as 3-4 hours of running per week.
'Endurance exercise prompts the heart to adapt in the short term, sometimes impairing its function,' he says. 'Over the long term, it can lead to structural changes and an increased risk of heart rhythm issues, such as atrial fibrillation.
‘However, the benefits of aerobic exercise remain substantial. I would encourage all runners to continue their training with careful planning and preparation for endurance events to support their heart health.’
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Rick Pearson is the senior editor at Runner’s World UK. He’s been with the brand since 2017 and loves testing PB-friendly shoes for on and off road. Rick is a sub-three marathoner and occasionally likes to remind people of this on the Runner’s World podcast, which he co-hosts. He once raced a steam train over 14 miles (he won, narrowly) and a horse over a marathon (he lost, comfortably).
