Earlier today, while at the gym, I was talking with a trainer about how to get the most benefit from my cardio days. He introduced me to the Karvonen Formula, which may be old hat for some of you. For those that havent seen this before, hopefully you'll find it as interesting as I did.
Basically, the Karvonen formula calculates your target training zone based on your maximum heart rate and resting pulse.
The formula works like this:
220 - age = Maximum Heart Rate (MHR) (MHR) - (Resting Heart Rate) = Heart Rate Reserve (HRR)
Your target training zone is anywhere between 60% to 90% of your Heart Rate Reserve plus your resting heart rate.
HRR * 60% + RHR
So, lets take me:
220 - 31 = 189 (MHR) 189 - 70 = 119 (HRR) I determined my resting heart rate by taking my pulse just after waking up in the morning.
119 * 60% + 70 = 141 119 * 75% + 70 = 159 119 * 90% + 70 = 177
So, my target training zone is between 141 and 177 beats per minute. This is easy enough to count off using a second hand. Divide the number by 6, and you know how much you need to be during a 10 second span.
The idea here though is to mix things up. If you always train at 60%, you'll develop endurance with no top end speed. Conversely, if you train hard most of the time, you'll never recover completely and your performance will be poisoned by chronic fatique. The best idea is to stay below 80% on the easy days to build a good base and push above 85% when its time to really go hard to improve high level performance.