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Karl Etzel
@karletzel
34
Health & fitness tech, wearables, the occasional random life post.
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191
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Location
Silicon Valley
Website
http://www.system3.co
Created
2016-12-30 02:07
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karletzel
habits
2019-07-06 12:30
Old dogs, new tricks
I've lately been more conscious about the effort required to change deeply held beliefs, in particular the ones you hold about yourself. Being very cerebral I tend to fall back on data and facts in assessing
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karletzel
cycling
2019-06-22 20:49
The most underrated piece of cycling gear
Cycling pro tip of the day: I just wanted to highlight one of the most useful pieces of gear that I see almost noone else using, and that is the helmet cover: Your mom always told you to wear a hat because
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karletzel
backpacking
2019-06-17 19:02
Kings Canyon NP, June 2019 trip
Every year I take the boys backpacking at least once, usually the high Sierras. This year we did not get to high (last year we made it to Glenn Pass). With all the snow pack the creeks and rivers are RAGING
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karletzel
rogan
2019-03-03 22:06
Art Imitating / Reflecting Life
Adding a little more random content to my seldom-updated blog for 2019. I've twice had the experience in the last 6 months of seeing something in media or popular culture which really resonates or speaks
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karletzel
fasting
2019-02-02 15:31
Fasting and HRV, part II
Lest you think (as I did) that the first time was an anomaly or random: And with a second system / measurement device (this one more accurate - the Firstbeat Bodyguard used with their Lifestyle Assessment),
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karletzel
fasting
2019-01-25 16:00
Fasting and HRV
Can you guess which night I was 24 hours into a fast? 113 ms might be my highest HRV ever. I have begun extending my weekly fast to 36 hours (IOW I ate dinner Monday night and did not eat again til Wednesday
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karletzel
cycling
2019-01-13 20:23
FTP, Zwift, Shoulder work
Training binge over the holidays worked, did an FTP test on Zwift today (nothing magic to Zwift, it's a standard 20 minute protocol but Zwift has one pre-programmed with a really efficient warm-up effort),
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karletzel
sleep
2019-01-06 05:24
Sleep tracker comparison
Quick note on a comparison I ran over the holidays on 4 (yes, 4 in parallel) sleep trackers: Oura, Firstbeat Lifestyle Assessment, Vital Scout, and the latest entrant, Beddr. Oura is a ring, Vital Scout
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karletzel
cycling
2018-12-26 03:15
Day 1 of a training block
For a variety of reasons I have the week off to get some work done and I'm training a lot, my goal is 3 hours per day. The plan is 4 days doing 3 hour rides and then the other 3 days, ride 90 minutes and
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karletzel
cycling
2018-12-25 14:20
End of year binge
The blog's been quite a while, life has been full. Started a new FT gig in a startup, scaled back a number of things, found some new devices I wanted to test, and working on building up the work capacity
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karletzel
hrv
2018-10-20 13:10
Stress Analytics and Training Load
Been tweaking the training up a bit lately and shortening my weekend rides, just getting too bogged down and tired on my long-ish loop to Page Mill. Rode last weekend with a pretty fast friend who races
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karletzel
cycling
2018-09-24 01:56
Some new carbon goodness, fall riding, prepped for winter
Wow been a long while, been super busy with a new FT gig in a medical device startup and my ex was outa town so I had a long stint in solo dad mode. Anyways...fall riding is gorgeous lately, I've been
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karletzel
cycling
2018-07-22 23:47
Chill day up Hwy 9
Nothing too dramatic today, I had a somewhat rough week in terms of just feeling super fatigued, so I took it a bit easier today: My time up Hwy 9 was about 2:30 slower than my time last week, but still
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karletzel
cycling
2018-07-15 22:12
Nootropics for Athletic Performance - Day 1
Two stories from my day today, one was just an overall very solid ride with a new PR on my local climb: I felt on the climb like I was going well, so I'm not too surprised by this. My Garmin 935 reported
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karletzel
testosterone
2018-07-11 02:40
Testosterone Optimization
Quick post about a very important topic - hormone optimization. You can't optimize what you don't measure. I use InsideTracker for all my blood work. Check them out: One of my projects of the last few
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karletzel
cycling
2018-07-08 21:44
New PRs, and VO2max intervals, and needing a rest
After my backpacking trip I had a super sluggish week, as I indicated last week. Then I did my usual Sunday loop (Highway 9 - Skyline - Page Mill - Foothill home) after a week or so of recovering and turned
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karletzel
hrv
2018-07-03 13:26
HRV Analysis of 6 days Backpacking
For this backpacking trip I wore the Firstbeat Bodyguard and ran the data through our Lifestyle Assessment ( Here are a few notes from the report. First up is the fact that my HR numbers clearly show the
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karletzel
cycling
2018-06-28 00:36
Some Altitude work
Been a hectic start to summer, just back from the Sierras with my boys. Legs have been super sluggish - One of my local warm-up hills, a good 40 Watts less than I had been doing for a while there. I should
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karletzel
fitness
2018-05-09 22:38
Training update, fatigue vs. intensity
Here's yesterday's ride from TrainingPeaks: One thing that I really notice after so many years away from racing is that hard efforts leave me really wasted. I had 3-4 efforts yesterday where I really pushed
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karletzel
cycling
2018-05-02 01:53
VO2max, another small step
Load up the training volume, things improve. Here's some background behind VO2max: If you don't know your score, and you are serious about fitness, you should.
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