Or how much energy your body is putting into healing, leaving less for spin class.
We often have patients get very frustrated over how weak they feel. So we spend a lot of time reminding them that healing takes a lot of energy, even though it doesn't feel like "work." (the real worrisome ones are the folks who start DIETING during acute injury/post surgery, thinking that since they aren't active their body doesn't need as much food! EEEEK!!)