Is there a single term (preferred) or two-word phrase (acceptable), possibly technical, though not necessarily so, that conveys the idea of a person having extreme strength and skill at stationary muscle control?
By this, I mean able to remain still in a stationary, possibly rather awkward, position for extended periods of time. Think of extreme yoga positions held for some extended length of time (granted, some of those one could not hold for too long; I'm thinking an hour or more, like this abdominal plank record).