Published: December 20, 2007

 

THE Spinning class at our local gym was winding down. People were wiping off their bikes, gathering their towels and water bottles, and walking out the door when a woman shouted to the instructor, “How many calories did we burn?”

 

“About 900,” the instructor replied.

My husband and I rolled our eyes. We looked around the room. Most people had hardly broken a sweat. I did a quick calculation in my head.

We were cycling for 45 minutes. Suppose someone was running and that the rule of thumb, 100 calories a mile, was correct.

To burn 900 calories, we would have had to work as hard as someone who ran a five-minute mile for the entire distance of nine miles.

Exercise physiologists say...