02 October 2024

Let's use a heart-rate monitor to gather data about our cardio-vascular fitness!

Several of the following observations were originally posted to the Fifty+ Years Old Forum at mtbr.com on 01 October 2024.



I started riding with a heart rate monitor, a Garmin Forerunner 45, in April 2024 and, after several months of data collection, I now find myself absolutely fascinated by what I've been learning about my cardio-vascular health and fitness. I am especially intrigued by the corroboration of what I feel has been a distinct increase in my overall-fitness and threshold-endurance during this summer's riding season. 

Bottom line: I love doing the things I get to do outdoors. My objective in learning to use a heart rate monitor has been to better understand my general overall fitness and health and, quite simply, to maximize however-many years might remain to me to continue to be able to do these essential activities that I love. Below is an inexpert run-down of what I think I'm beginning to understand better about my body based on what my new monitor seems to be telling me.

HISTORY
I'm male and currently 57 years old (almost 58, tbh). I'm 6 feet tall, weigh about 200 pounds, and my resting heart-rate is typically around 50ish beats per minute. I have occasional stage 1 hypertension which, in my case, is definitely exacerbated by my alcohol intake and/or how badly I'm dehydrated. If I'm being honest, both of these conditions happen to me with some frequency.  My bad cholesterol is for shit, but my most recent cardiac calcium score (done earlier this year) is 5. I was treated for asthma exacerbated by allergies as a child, but have suffered no ill effect from this juvenile condition as an adult. I have no other cardio-vascular or pulmonary issues that I'm aware of.

I was never an athlete as a kid, at least not of the organized team sports variety.  But I swam a lot and rode my BMX bike and/or my paper-route bike somewhere almost everyday while growing up.  As an adult, I have been riding singletrack in our high-elevation (7000-9000') forest 100+ days a year (averaging about 1500 miles a year since 2011 when I started using Strava) for more than 30 years. During my cycling off-season, typically early December through late April, I Telemark ski on the regular, usually 4-5 hours a day, 4-5 days per week, at elevations generally above 10000' at our local ski area.  I like to think I know my body, my gear, and my "backyard" pretty well at this point at this point in my life.  

We live on the talus slopes of a big shield volcano, so almost all my rides are loops which begin with a prolonged ascent and end with a similarly prolonged (but never identical) descent. This unavoidable topographical reality makes it easy to look at my sustained and/or interval efforts in large linear blocks of both time and distance as I climb consistently upward on terrain I'm very familiar with. 

PREPARATION
Initially, when first setting up my heart-rate monitor out of the box, I used the 220 minus chronological age formula to determine my max rate, which I therefore set at 163. But after riding for several weeks at this set-point, I noticed that, per my post-ride data, it appeared I was spending a fairly large percentage of my ride in the anaerobic Zone 5 range which, after doing a little research, I found should not be possible, or at least was not desirable. 

This insightful response to a comment I made in July 2024 in the Max HR at 50+ thread in the Fifty+ Year Old forum on mtbr.com helped me understand all of this a bit better:
Dunnigan replied: It sounds like you might not be at your theoretical max HR, which is fine. If a rate feels uncomfortable, even a suffer fest, but you can keep it up for 3 min, that sounds more like an anaerobic effort—you are above your lactate threshold, and lactate is building up faster than you can clear it. That zone feels like your body is asking, then insisting, then begging you to slow down. The forceful breathing of working at just below your threshold is replaced with gasping for air, unable to keep up with demand for more Os.

I haven’t read that there’s any real training value in chasing a theoretical max. It takes extraordinary motivation, e.g., a contested finish in a race. Then you’d still not know how high you might get if that other rider were replaced by a grizzly bear on cocaine.

The 220-age to give a max, then taking percentages of that for zones isn’t reliable enough. What you describe above when listening to your body is far more accurate for what zone you are in. That rate above which efforts can’t last more than a few minutes is likely a good estimate of your LT (somewhere around 165). If that cocaine bear were chasing you, you might be surprised at what your watch read. So the 145-155 might be referred to as tempo. Thats a fun spirited pace to climb at.
Using Dunnigan's observations as a guide while drilling down a bit further into my own research, I eventually concluded that, based on my data, the actual rate at which I can't "comfortably" sustain an effort for more than a few minutes is more like 170. And that my "yer gonna blow-up" rate, where I have only a mere handful of seconds of effort in my legs, is about 174-175. I know none of these set points have been derived per the scientific method, nor have they been rigorously evaluated by a sports physiologist, but they're definitely accurate, as in they're based on my very own personal sample-of-one real-world ground-truthed experiences. So, for now anyway, I've set 170 as my functional max heart rate.  And I'm going to stick with that until someone or something changes my mind. 

GOALS
As I stated above, my primary objective in learning to use a heart rate monitor has been to better understand my general overall fitness and health and, quite simply, to maximize however-many years might remain to me to continue to be able to do these essential activities that I love.  That being said (again), I've set a few goals that I hope will help me achieve this result.

First of all, this summer I've been focusing on extending my warm-up time at the beginning of every ride by deliberately staying in zone 2 as I'm headed out of my neighborhood into the woods.  I've learned that this makes me feel significantly better once real effort of the ride begins.

This season, with the data from my new monitor to guide me, I've also been working diligently to extend the percentage of time, and to increase the number of days per week, wherein I'm able to ride near my anaerobic threshold, in the upper part of zone 4. For me this occurs between 155-164 bpm. 

FOCUS
While I've been engaged in extending my at-threshold cardio-vascular capability this summer, I've likewise been trying to tune-in to familiarizing myself with how these efforts feel, without looking down at the watch-face to see where I'm at.  I'm trying to listen more closely to my heart rate, in my chest and in my ears, and to practice effective, deliberate breathing, and also (perhaps best of all) to find that place of peaceful mental contentment while on the bike.  Don't know about you, but I have always loved that sense of being on top of the right gear when you're in it, that sense that there is a strong tailwind at your back, heart beating strong, right in the middle of zone 4, those moments when your cadence and your power make you feel like "I could ride like this all day."

MAINTENANCE
I've also been making concerted efforts to balance my activities this season. And I've been paying close attention to the Relative Effort number on my Strava to better understand this concept.  It continues to be my goal to get in 50+ on-dirt miles per week.  But for the first time in forever, I'm also deliberately making sure I give my body time to recover after bigger efforts.  As I find myself aging, and recovery seems to take a bit longer, I'm being more attentive to the types of rides I'm doing, making sure not every ride is an epic (but that there's at least 1 bigger effort, sometimes 2 each week), making sure to go on a few dirt road gravel bike rides, mellow singletrack toodles (mostly in zone 3), or what I like to call "errandonnée" rides (which just means riding around doing random shit via bicycle) around town, keeping things a bit more spinnie a couple days each week.

GAINS
The last thing I'll mention is something I've been noticing more often lately, especially this past month (September 2024). Along with a perceived increase in general fitness and my perception that I'm feeling really good on the bike these days, I'm also noting an increase in my ability to maintain a faster rate of speed when riding uphill for extended periods of time, all while keeping my heart rate well below my max.  I'm stoked to report, I've surpassed several long-standing Strava PRs in the past few weeks, every one of them while maintaining a confident, fast, sustainable cadence for a prolonged period of time (50-60+ minutes) at heart rate consistently in my zone 4 range.  I'm still processing this new piece of data, but I'm excited by these results, they feel valid!

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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. -- Ed Abbey