Sunday, March 20, 2016

Forerunner 25 zones revisited

First thing is to understand where the story left off. If you don't know what happened during my first run with the Forerunner 25, you'll be kind of lost here.

I tweaked the zones, and think I over did it. Last time they were reading too high, or so I thought. Today I got on the bike with a pencil and paper handy. After getting warmed up, I set up to produce a specific amount of watts, and recorded some info. The goal watt numbers are derived from a Functional Threshold Test done over the winter.

The idea here is to put out the maximum power you can maintain for 20 minutes. At first it's easy, then gets harder. My number was 225 watts, and using Training and Racing with a Power Meter 2nd edition by Hunter Allen and Andrew Coggan I had previously determined my watt ranges. That's the top list in the photo. They've lined up pretty well with what I feel during spin sessions.

The bottom list was based on max heart rate percentages by Karvonen method. If I'd thought about it at the time, I'd have know right off that something was wonky. 50% of 163 is not 105. It's 81.5. Except there's something else in the calculation too, the heart rate reserve. Here's the screen shot.

So today this is what I got pedaling for 10 minutes in each zone, with a break in between:
158 watts (nearly top of Endurance pace) 108/109 BPM, zone 1.2 per watch, or 66% of max heart rate by calculation. Breathing was deep and easy.
190 watts (top of Tempo pace) 118/119 BPM or zone 1.9/2.0 by watch, or 71% of max heart rate by calculation. Breathing was harder, but still regular and deep. Beginning to get a bit of a sweat on.
225 watts (Lactate Threshold) 129/130 BPM or zone 3.0 by watch, or 80% of max heart rate by calculation. Breathing really hard and deep, but not panting. The fan is on high. I think I could have gone another 10 minutes to repeat the threshold test, but I wasn't in the mood for that.

Running at the average of 125 BPM yesterday was chat pace. I'm not sure why the same heart rate has me breathing so much harder on the bike. Something isn't adding up. Then I found this chart here to compare % of Max heart rate, to the Karvonen which is Max heart rate minus resting.

If I look at the left most column, it lines up really well with my spin numbers today. But at least so far, the Karvonen numbers seem to work for running. I'll have to track this a bit more. Fortunately, the Garmin app offers 3 screens, a default, cycling, and running. Looks like I'll have to go through and set each. I know it knows when I'm running, I hope it's smart enough to figure out when I'm biking. I don't remember a way to select the activity on the watch. Maybe I missed it.

Overall it worked out to 1.25 hr on the bike. One last little factoid. My heart rate dropped by 15 beats per minute in one minute from a 130 beats per minute effort level.

The big amusement here this morning was giving the cats a hit of catnip. Linda loves doing this. It's quite the show, but this is the first time I've caught it on video.

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