Eliud Kipchoge of Kenya crosses the finishing line to win the Berlin Marathon 2018 in a new world record time of 2:01:40 hours (later officially annouced by organisers to be 2:01:39) on September 16, 2018 in Berlin, Germany.  (Photo by Maja Hitij/Bongarts/Getty Images)

What are the limits of human endurance?

We teamed up with the folks behind BBC World Service's CrowdScience to answer your questions on one topic - this week it's all about human endurance.

Is endurance in the mind or in the muscles?

When it comes to running, how far and how fast you can go is determined by a number of physical factors, including your VO2 max (the volume of oxygen you can pump round your body) and your lactate threshold, which is the point at which your body produces more lactate than it can break down (a build-up of this chemical makes you run less efficiently).

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Some of this is genetic; some of it comes from training. But in recent years, sports scientists have also come to recognise the importance of mental strength. The longer you run, the more important a well-thought-out mental strategy is. Common strategies for coping with pain include motivational self-talk and distraction techniques to help block negative thoughts.

Kate Smyth was escorted from the track when she collapsed after running the marathon at the 2006 Commonwealth Games © Getty Images
Kate Smyth was escorted from the track when she collapsed after running the marathon at the 2006 Commonwealth Games © Getty Images

Will anyone ever run a two-hour marathon?

Thirty years ago, scientists calculated that the fastest possible marathon, in perfect conditions and with the perfect athlete, would be 1 hour 58 minutes. And we’re getting close. This September, Kenyan long-distance runner Eliud Kipchoge set a new world record of 2:01:39 at the Berlin Marathon – a race ideally suited to fast times because of its flat course, few corners, and typically good weather conditions.

Sports physiologists think that the two-hour limit could be broken in the next few decades, as a bigger talent pool of runners, plus advances in training technology, create ever more ideal combinations of athlete and running conditions.

Is endurance running bad for you?

Long-distance running stresses the body: recent research from the University of the Peloponnese in Greece found that post-race levels of inflammation in the blood of ultra-endurance runners (those who run races longer than a marathon) showed similar profiles to people with cancer or cirrhosis.

However, over the next few days, the runners’ levels returned to normal, suggesting that they have a remarkable ability to recover after an extreme workout. Good training is partly about building an awareness of your limits, so that you know when, for instance, you’ve crossed the line from ‘good pain’ into ‘bad pain’.

Could humans live in underwater cities? © Getty Images

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