Paweł Poljański is a 27-year-old Polish racing cyclist.
He's currently riding for Bora–Hansgrohe in the Tour de France.
He's been racing since the first race day, 1 July, and is placed in 75th after 16 racing days, and only two rest days.
He's been riding for 70 hours, 13 minutes and 50 seconds, so far.
He's also recently shared a photo to Instagram of what his legs look like at this point in the competition:
He's got five of the 21 stages left to go.
In 2014, Chris Froome, current tour leader, posted a similar image, showing the effect of competition on his legs:
Dr Bradley Launikonis from the University of Queensland's School of Biomedical Science told the ABC that the veins in his legs are swelled with blood, due to the ongoing competition:
The amount of blood that we get normally going down to our legs is five litres per minute, for anyone at rest. For an untrained athlete, their maximum exercise will have 20 litres per minute flowing through the muscles.
One of these elite cyclists will have double that, about 40 litres per minute. They have massive volumes of blood moving through.
After he's finished exercising, the veins are showing up. Blood flow is pressurised through the arteries in a highly regulated fashion.
What we're seeing [through the skin] are the veins, and there's a lot less pressure in them [than arteries].
There's a high level of blood being pushed into his legs for long periods of time, and it's still in there post-exercise.
It's really something that shouldn't be commonplace in an everyday recreational cyclist, only elite performance athletes like Pawel.
So if your legs look like this after a gentle 20km bike ride, it's probably not a great sign.