Heart Rate

On the commute this morning, I revelled in the fact that my early morning ride to work is significantly easier than my ride home. It took me 61 minutes to get to work (versus 68 to get home yesterday) and my average heart rate was 141 (versus 152 yesterday).

It made me think about my Resting Heart Rate (RHR), which at last (recent) check was about 42 beats per minute (BPM) and my Maximum Heart Rate (MHR). According to Wikipedia, there are several formulas:

• The most common formula encountered (Fox and Haskell, 1970), with no indication of standard deviation, is: HRmax = 220 − age (for me = 182)
  Unfortunately, this method has an error ranging from 7-11 BPM!
• Another formula deemed least objectionable is: HRmax = 205.8 − (0.685 × age), which for me is 179.77 (gotta love the .77), which a more acceptable standard deviation of 6.4 BPM.

Unfortunately for me, I know that my MHR is more than 180 as I've seen it go to 186 on the heart rate monitor (recently).

So the MHR and RHR help determine the Target Heart Rate (THR) depending on how hard one wants to exert him/herself.

THR = ((MHRmax − RHR) × %Intensity) + RHR
Examples for me with a MHRmax of 186 and a HRrest of 42:

• 50% intensity: ((186 − 42) × 0.50) + 42 = 114 BPM
• 75% intensity: ((186-42) x 0.75) + 42 = 150 BPM
• 85% intensity: ((186 − 42) × 0.85) + 42 = 164.4 BPM

So my intensity yesterday was about 76% and my intensity today was about 68% - that's the training lesson the day!