April 2023

I promised I'd not inundate you with too many emails and I am keeping that promise. February, March? Yeah those newsletters never happened. I'm planning to be more consistent going into the summer. I have some cool content queued up. Onward...

A trend I'm excited about is over the counter (OTC) hearing aids. We buy augmentation for our eyes (sunglasses, readers) OTC, so why not our ears? Most of these devices have a mobile app that essentially provide an at home hearing test to help tune the device. The advent of active noise cancellation in consumer earbuds also blurs the line between simple devices to play music and hearing aids. At CES I saw HP announcing a product in this category, and Eargo is often cited as a leading innovator in the category with a smaller, less visible device. Both are FDA cleared.

I've been digging into metabolism more lately and this is one of the more interesting things I've learned about. Apparently there's an upper limit on how much exercise you can sustain that can be calculated relative to your basal metabolic rate (BMR). "...we find evidence for an alimentary energy supply limit in humans of ~2.5× BMR; greater expenditure requires drawing down the body's energy stores." As for measuring BMR, I'm very interested in a technique known as doubly labeled water, which is expensive but very accurate in measuring how many calories you're actually burning. This presents another way to assess how much training is too much. Alongside traditional CTL/ATL/TSB methods, I think this could be a nice way to triangulate the optimal training load as your fitness develops.

Last month I wrote about my training approach. This month I'll address one way to think about "how long is long?" One metric you can use to help assess this is aerobic decoupling (AD). To understand this concept you need to understand EF - efficiency factor, which is the ratio of normalized power to heart rate (I'll speak in terms of cycling power, but there are analogies for running as well). Higher EF simply means more watts per heart beat. Aerobic decoupling (Pw:HR, in Trainingpeaks) compares the EF from the first half of a workout to the second half. IOW, if you were operating at perfectly constant power level, AD measures how much your HR goes up to keep making the same watts. Note that all of this works only for steady state efforts, intervals throw off all the numbers for several reasons. From the data below you can see that for this 3 hour 12 minute ride my AD was 13.32%. So for me, when I did this workout, 3:12 was kinda long - ideally, Pw:HR would be under 5%. My fitness simply didn't allow me to do this whole ride without some real fatigue creeping in and driving down my efficiency.

Here's a ride from several weeks later - shorter ride, lower decoupling, higher EF. 1:48 was more in line with my fitness, and also my fitness had improved a bit.

These data are all from Trainingpeaks and you can start to see how they capture what you intuitively feel - when you go really "long" (whatever that means for you), you simply can't produce the same watts at the end of the ride for a given HR or exertion level.

It's also worth noting that a number of factors besides fatigue can drive AD - in particular, fueling, hydration, and heat. So if you start off in cool temps, and end in higher temps (which we often do here in the Bay area), you need to consider this in your numbers.

Youtube has some crazy interesting content on so many topics. Lately I've been watching videos from Blancolirio, who covers California water management and related civil engineering projects. Apparently he's also a pilot so some videos have cool aerial views of dams and reservoirs.

One of my favorite quotes, and like many attributed to someone without solid proof that he (in this case, Winston Churchill), actually said it.

I never get tired of this place. Riding in Morgan Hill on a chilly late winter morning.