Dave Castro has just taken on the business equivalent of a hospital pass.

He’s the new boss of CrossFit, which is part ultra-high intensity fitness “philosophy”, part competitive sport, part (from the outside) slightly scary looking outfit subscribed to by people who probably revel in the description “hard charging”.

Its members include hedge fund managers, extreme sports participants, those who leave ordinary folks needing a lie down after spending five minutes in their company. You know the drill.