Longtime readers will recall that I’ve written about overtraining, under-recovering and exercise-induced illness before (e.g. Don’t Get Sick and Overtraining in MMA). It sucks to have a streak of hard training sessions interrupted by the flu, and being overtrained makes catching that flu almost inevitable.

About the only objective measure of overtraining I know of is to track morning resting heart rate. To do this take your pulse before you get out of bed: after a week of doing this you’ll have a pretty good idea of what your normal rate is. If your heart rate on a given morning is 10% or more higher than normal you might be coming down with something and/or be inadequately recovered from your last training session.

Most mornings I reach for the stopwatch and take my pulse for 30 to 60 seconds. These days I’m usually reading between 42 and 44 beats per minute. If I wake up and my heart rate is higher than usual – more than, say, 46 beats per minute – I monitor my body and energy levels very carefully that day. If I notice other signs of sickness (e.g. fatigue, sore throat, etc.) then I will either train very lightly or not train at all that day.

Another advantage of tracking resting heart rate is that it can tell you when your fitness is increasing or decreasing. A gradually decreasing resting heart rate usually indicates improving aerobic (and possibly anaerobic) fitness. Your resting heart rate can also go down if you lose a lot of weight, since your heart now has less body mass to force your blood through.

On a side note, one of my fitness goals is directly related to resting heart rate. I’ve been doing a lot of running and cardio recently, and my goal is to wake up one of these mornings and find out that my resting heart rate is 39 beats per minute or less. Wish me luck!