Is marathon running actually safe?

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Yes

The marathon, a 26.2-mile test of endurance, sparks something ancient in us. “We evolved for long-distance running, probably starting about two to three million years ago, to help our ancestors hunt,” says Professor Daniel Lieberman, an evolutionary biologist at Harvard University.

That legacy shows up in our biology. A 2020 University College London study of 138 first-time London Marathon runners found that training reduced blood pressure and aortic stiffness – enough to reverse the age of your arteries by about four years. Dr Anish Bhuva, a cardiologist at UCL, who co-led the study, says that “the biggest improvements were in older runners with higher baseline blood pressure”.

The benefits can also extend to the skeleton. As Professor Alister Hart, an orthopaedic surgeon at UCL, notes: “The kneecap has the thickest cartilage in the body because it takes the greatest load.” In his MRI studies, runners who followed the four-month London Marathon training plan – with modest weekly increases, strength work and recovery – showed no joint deterioration during the plan, and some improved. “Bones need impact, they strengthen through it,” he says.

The psychological benefits of running are equally compelling. Professor Andrew Lane, a sport and exercise psychologist at the University of Wolverhampton, says running “reduces tension, depression and fatigue, and increases vigour”. Structured training also builds self-regulation and confidence under pressure. As sport psychologist Dr Josephine Perry says, it “adds routine and purpose, reduces overthinking and gives people a sense of belonging”. She also cites research from the Department of Psychiatry and Biobehavioral Sciences at UCLA that suggests that “those with higher fitness [levels] can process information more quickly”.

Some benefits may improve health on a cellular level. Studies have found that endurance athletes had longer telomeres – the protective caps on chromosomes – suggesting that regular training may slow aspects of biological ageing. 

No

Cardiologist Dr Carl Lavie describes the “sweet spot” for endurance exercise as being about 30 to 40 minutes a day. This delivers the greatest cardiovascular gains, whereas routinely exceeding 10 hours a week may nudge you into a zone where risks such as atrial fibrillation (irregular heartbeat) or increased coronary artery calcification (which can lead to coronary artery disease) rise. For middle-aged runners stacking multiple marathons or ultras, he recommends precautionary screening – an ECG or coronary calcium score – to rule out hidden heart disease before the training load ramps up. Adds Dr Bhuva: “Running a marathon is not the right goal for everyone, and it is best to check with your healthcare providers before you commit.” 

According to studies of ultra-endurance events, between a third and half of participants report musculoskeletal issues. MRI studies have shown temporary cartilage swelling and soft-tissue changes after extreme endurance events; ultra-endurance specialists, such as Guillaume Millet, a professor at Jean Monnet University in Saint-Étienne, note that ultra-distance running places athletes close to the limits of physiological adaptation, with fatigue and tissue strain increasing injury risk if recovery and conditioning are insufficient. Says Lieberman: “I do not think they do this for the sake of their health; it is for complex psychological reasons.” He also notes that humans may be built for endurance, but not for monotony: “We never evolved to run 26.2 miles on tarmac.” His research shows that ancestral movement was a mix of walking, occasional running, lifting and carrying – not repetitive pavement miles.

“It is a Goldilocks dose,” says Hart. “Too much and you risk stress fractures, too little and you risk weak bones.” Around 90 per cent of runners will pick up an injury, most often around the kneecap due to poor patellofemoral tracking (when movement around the kneecap isn’t aligned, often as a result of overuse). “Conditioning such as glute bridges or cycling where the leg moves in a fixed, coordinated path helps keep the knees tracking smoothly.”

The mind has limits too. Lane warns that running becomes counterproductive when “the pursuit of distance or personal bests starts to erode mood, relationships or recovery”. As Lieberman says, “you do not need to run marathons to get the benefits. We evolved to move, and running is the most fundamental kind of physical activity.”