On Monday, 17 March 2014 20:09:46 UTC, Chris wrote:
The gym has machines by pulsefitness.

An adult needs about 2000-2500 KCal a day - or very roughly 1-2 KCal per minute.

Even if you'd just sat next to the bike for 9 minutes, you'd have used (very roughly) 10-20 KCal, just staying alive and maintaining your body temperature.

IIRC vigorous exercise raises our heat output by about a factor of 2-3x compared to doing nothing.

So the overall figure of 50 KCal sounds reasonable - but remember that the *excess* calories used by exercise is somewhat less than that.