This morning I went out for a ride on my usual local loop. It includes a good mix of flats, hills and head winds. The loop is about 26km long and used to take me well over an hour to complete when I first started training last year. Now I am easily completing it in 50-55 minutes depending on the level of effort I put in and whether I take a cool down at the end.
I decided to just see what my heart rate did while I rode with the goal of sticking to the lower end of the Schurmanns’ formula’s tempo range (103 – 117 bpm). My resting heart rate is 48 bpm so that’s where I started at 5:40am when I finally got out of bed (it was so comfy in there listening to the birds singing outside my window). My heart rate as I was getting ready to ride was about 78bpm. That didn’t seem like it left a lot of room to make 103-117bpm my tempo range.
By the time I was at the main road, about 400m from home, my heart rate was 110bpm and I was barely spinning my legs on the pedals. I realised that there was no way 103-117bpm is my tempo range. I settled into a pace that meant I was working just hard enough to have to regulate my breathing but not hard enough that I was feeling stressed. I found my heart rate was sitting somewhere around 155bpm, which is well over my heart rate reserve according to the Schurmanns’ formula. So as I cruised down a quiet backstreet I did some mental arithmetic and found that if I didn’t reduce my maximum heart rate by my resting heart rate I would actually be sitting somewhere in the 75% – 85% range if my heart rate fluctuated from 140bpm – 160bpm (roughly).
I maintained an average heart rate of 152bpm for the first 24.40km of my ride and then 129bm for the last 5 minutes. During the main part of my ride my heart rate followed a steady pattern: 155-158bpm when riding dropping to 138-140bpm when rolling down hills.
I suspect I misunderstood the Schurmanns’ formula and I’ve loaned the book to a friend so can’t just check it. I’ve used an online tool to recalculate my heart rate zones. I found this site had a good explanation for me and the zones it calculates are consistent with those I’ve calculated manually and on other sites. I’m only using this site because it’s the first one I’ve clicked on this morning – there might be better sites.
RHR = 48bpm
MHR = 189bpm
HRR = 141
Fat burning (50% – 60%) = 119 – 133bpm
Aerobic (60% – 70%) = 133 – 147bpm
Steady state (70% – 80%) = 147 – 161bpm
Anaerobic (80% – 90%) = 161 – 175bpm
Max (90%+) = 175bpm+
So this morning I sat comfortably in the steady state range. And that’s exactly what I felt like I was working at.
Total: 26.04km @ 28.7kph