Study About Running During Coronavirus Pandemic ‘Massively Misinterpreted’


Bert Blocken/Twitter/Pixabay

Earlier this month, an article telling people not to exercise close to each other in order to prevent the spread of coronavirus went viral.

The article referenced a study – which, it needs to be noted, isn’t peer reviewed – and warned people against walking, biking and jogging, even from the recommended distance of two metres.


In just a short matter of days, the article had popped up on Twitter, Facebook, even Whatsapp, with people using it as a way to criticise those who were exercising outdoors.

people cyclingPixabay

There’s only one problem though. Well, there’s actually two problems, the first being that the study referenced isn’t peer reviewed – as I mentioned above.

Instead, those behind the study reversed the typical order of getting things done: initially, speaking to the media first, hence the viral article; secondly, submitting a proposal for funding; and then finally getting the research peer reviewed.


They did things this way because the crisis is ‘urgent’, Professor Bert Blocken, the co-author of the study, explained on Twitter, adding: ‘It was a race against [the] clock to get results ready, confirmed, validated and animated.’

Blocken continued:

A few people criticise this study has not been peer reviewed. Seriously? Crisis is world-wide, situation urgent, people are dying, economy crumbling. Should the public wait for months until peer review process is finalised?


The second problem is that Blocken has since come out and branded the viral article a ‘massive misinterpretation of [their] work’, with the author telling UNILAD the intention of their study was not to warn people against exercising but ‘to put peoples’ minds at ease’.

Blocken, a professor in Civil Engineering at Eindhoven University of Technology, the Netherlands, and KU Leuven, Belgium, explained:

The ‘massive misinterpretation’ that I used was a response to many people replying that runners and cyclist would ‘spread the coronavirus’ and that you would get coronavirus when a runner or cyclist passes you. That is not true.

We never said that and we never said anything about infection risk. We do not study infection risk and there is no evidence to state that you will get infected when running or cycling behind another person.

There is also no evidence to the contrary. We just indicated ‘equivalent social distances’ and asked people (experts in virology, government) to be consistent.

people runningPixabay

The professor explained that while the viral article itself was ‘not incorrect’, it ‘incited suggestions about infection risk’ that ultimately led to people sharing it. ‘But I do not blame the author, he is a kind and fair person,’ Blocken said.

So what was the gist of the article? Initially headlined ‘Why in times of COVID-19 you can not walk/run/bike close to each other’, but later changed to ‘Why in times of COVID-19 you should not walk/run/bike close behind each other’, the article seemed to suggest all forms of outdoor exercise should be avoided.

At least, that would be the case if you went solely off the headline, which is what the majority of people were taking from it – a tried and tested way for things to get completely misconstrued, as we all know.

people walkingPexels

When you actually look at what the article is saying and what the study is saying, you’ll find both are simply advising people to keep their distance when exercising behind other people.

Blocken said he’d received ‘dozens of questions’ from people asking him for advice while exercising, anything from ‘How should I overtake a person when I am running or cycling?’ to ‘Should I hold my breath?’.

He told UNILAD:

Our study shows that this is not needed, but that if you [are] running or cycling directly behind another person – in the slipstream – to have the equivalent (non-)droplet exposure of two people standing still and talking to each other at two metres, you need to keep longer distances.

What we did is not rocket science. Actually we confirmed common sense and visualised it. The common sense is: when you exhale droplets and you start moving, you would [move] through your own cloud of exhaled droplets, but also a person following closely behind you can walk through this droplet cloud [too].

running droplets streamrealBertBlocken/Twitter

In simple terms, while the study found that two people walking/running/cycling side-by-side can stick to the two metres guidelines in the absence of a strong wind, this distance needs to be greater if the second person is walking behind, or in the slipstream of, the first person.

In this case, the equivalent social distances would be: five metres for those walking fast (4km/h); 10 metres for those running fast (14.4km/h); and 20 metres for those cycling fast (30km/h). ‘The social distance to be kept when in the slipstream increases with increasing speed of person B,’ the study states.

Blocken said he ‘had to share’ what he knew with runners and cyclists, although did accept fault for the way things went down, telling UNILAD: ‘And yes, it is our fault as researchers that we did not anticipate how the attention for this study could explode.’

running droplets streamflowrealBertBlocken/Twitter

After showing the research to Jennifer Dilley, a Consulting Epidemiologist, she said it does have ‘some pitfalls and limitations’, including that it employs modelled data, ‘which is potentially a biased look at real-world scenarios’.

She also noted that the study employed a constant temperature and unchanged conditions in running environment ‘which do not accurately replicate nature’, although she did acknowledge that the study ‘does address the limitation of wind directionality and other droplet emission’ and even suggests further study is needed in this area.

Dilley told UNILAD:

While the study does have some pitfalls, essentially these scientists are attempting to add to the knowledge base about COVID-19. In NO way are they recommending individuals not walk or run outdoors.

In fact, quite the opposite. They are offering recommendations to keep individuals safe when engaging in activities that increase droplet transmission (breathing hard, moving quickly).

The epidemiologist said all of the misinformation surrounding the study and the article was a ‘great example’ of a huge problem that exists currently – that we are currently in ‘an infodemic’.

‘Research for COVID-19 is coming out rapidly and not all is created equal,’ she explained. ‘I believe most scientists are trying to understand and gain more perspective of this illness. [But] when an individual who is not qualified to perform an accurate assessment on a scientific presentation (research articles), misinformation is shared.’

There is, therefore, absolutely no evidence to suggest people shouldn’t be exercising outside; in fact, the World Health Organization (WHO) recommends going outside for a walk, run or bike ride as long as your local/national guidelines allow it and as long as you’re able to keep a safe distance from others while doing so.

Blocken added that as long as we ‘be kind and courteous to one another’ by social distancing and respecting those who choose to exercise outside, we should be okay. ‘We are all in this crisis together,’ he said.

That we are – so let’s remember that next time we go to judge somebody because of their exercise routine.

It’s okay to not panic about everything going on in the world right now. LADbible and UNILAD’s aim with our campaign, Cutting Through, is to provide our community with facts and stories from the people who are either qualified to comment or have experienced first-hand the situation we’re facing. For more information from the World Health Organization, click here.

Topics: Health, Coronavirus, exercise, Running, Science, Viral


Bert Blocken/Twitter and 2 others
  1. Bert Blocken/Twitter


  2. Medium

    Belgian-Dutch Study: Why in times of COVID-19 you should not walk/run/bike close behind each other.


    Towards aerodynamically equivalent COVID-19 1.5 m social distancing for walking and running

Lucy Connolly
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