This is what I wrote elsewhere after hearing a lecture on December 12 in Papendal, the Dutch Olympic Sports Centre.

Professor Maria Hopman conducted a large experiment on 300 walkers during the world's largest walking event 'Vierdaagse' (4 day walking over 30 , 40 or 50km) held every year in July as well as another smaller experiment on runners during a 15K run (7-hills run) that's held every year in November.

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