I resumed heart-rate training this fall, after several years of recovering from a back injury. I wrote this summary of heart-rate information in part to remind myself of the major concepts:

Your resting heart rate is as slow as your heart naturally beats. Measure it right when you wake up, still lying in bed. My resting heart rate is about 50 beats per minute. This number increases with age and can decrease if you get more fit. If you are working out it’s good to measure your resting heart rate every morning, because if it jumps by 10% or more it’s a sign that you may have overdone it in yesterday’s workout. For example, I overdid it last Friday and my resting heart rate was 61. I took the day off.

Your heart beats faster as you get more active, of course, to serve your more active muscles. My heart rate gets to 60 or so just sitting, and 70 or so walking around.

Your maximum heart rate is the fastest your heart naturally beats. This number comes down as you age. Measure it by working out really really hard with a heart rate monitor on and seeing how high you can get it. Alternatively, if you are not in good enough shape to really push it yet, you can calculate a theoretical maximum heart rate by subtracting your age from 220 if you’re male or 226 if you’re female. There is some controversy about the accuracy of this equation, but I looked into it and the controversy looks like hair-splitting to me. The main thing to keep in mind is that if you calculate a theoretical maximum heart rate, it is not your actual maximum heart rate. My theoretical maximum heart rate at 41 is 179 beats per minute, which I hit during the aforementioned Friday workout, but the highest I’d seen it go before that this year was 165.

You can see that your range of heart rates you can narrows as you age, from the bottom and the top. I wonder if measuring your range of heart rates would be a good way to measure your biological versus chronological age, the way focal length is.

Heart rate recovery: One way to measure how in shape you are is to check how fast your heart rate descends once you’ve got it up by exercising. (Some do use this measurement as a real-versus chronological age indicator.) Just get it up pretty high, stop exercising, and see what it gets down to in one minute. My heart rate comes down about 40 beats in a minute, which is considered good.

Training zones: Exercises that cause your heart to beat at different rates have different physiological effects on your body:

Between 60 and 70% of your maximum heart rate is a mild aerobic “zone,” which increases your number of mitochondria, your capillary network density, and your efficient use of energy. According to the system I use (laid out in the book SERIOUS Training for Endurance Athletes), about 80% of your training hours are done in this zone. For me, it is between 108 and 125 beats per minute, which I experience as real exercise (I can’t get to it by walking, even very quickly) but pretty easy. I can follow the narrative of a podcast with no problem, for example, and in university I read many of my journal articles on an elliptical machine in this zone. (While I’ll give you my experience of these zones, keep in mind that you cannot use your subjective experience to judge your heart rate. Even the pros have to measure it.)

The rest of my training hours are divided in different ways between three other zones, depending on where I am in my year. Early on is mostly in the first zone and I gradually add in more of the other three.

The first of those is between 71 and 75% of maximum heart rate, and is a more intense aerobic zone than 60-70%, and has similar physiological effects, increasing endurance. I experience it as a sustainable pace, but not easy. I can no longer read and have more trouble following any narrative.

The second is between 81 and 90% of maximum heart rate, and is quite intense, used for short periods, like in sprints or interval training. That’s 144-161 beats per minute for me. I have trouble keeping it up for more than a few minutes. One thing that this kind of exercise does is essentially teach your fast-twitch muscle fibers to burn oxygen better, which lets them last longer. Exercise in this zone is called “anaerobic threshold training,” because it is the zone just before you hit the point that your heart and lungs really can’t keep up with your muscles. Staying in this zone can increase the heart rate at which you “go anaerobic,” or largely stop burning oxygen.

The third is the “anaerobic zone,” between 91 and 100%, which feels like all-out effort. Your heart and lungs can’t keep up the oxygen supply and can’t take the lactic acid away from the muscles quick enough. Your arms and legs get rubbery feeling pretty quickly. Training here is exhausting but can increase your speed and coordination.

I bought Sleep Cycle for my iPod touch because it sounded right up my alley. It uses the accelerometer in i-devices to measure how much you move while asleep to track your sleep cycles. Then it wakes you up when you will be most alert. How cool is that?

Well, it is pretty cool, but not because it tracks your sleep cycles, or because it wakes you up alert. First of all, sleep cycles are defined by brainwave patterns, not by movement. Perhaps it’s a decent analog–I’ve read that claim–but the charts that Sleep Cycle produces from my nights of sleep don’t look much like the examples of EEG readouts of sleepers.

Where in this graph was I dreaming? It looks like I fell asleep and woke up pretty abruptly, and was awake for a short period just after 6 am, but that’s all I can tell. I can also say that the app does not always catch it when you wake up. I’ve gotten out of bed to pee and not made a spike out of the sleep zone.

It is also not really useful for its primary purpose–to wake you up during the period that you will feel most rested. You set an alarm for the latest you want to wake up, and then a period of time during which it would be acceptable to wake up. The alarm is supposed to go off at the point in that period when you are moving enough to indicate that you are in shallow sleep. Supposedly, if it waited longer and let you go back into deep sleep, you would wake up groggy because of it.

Perhaps it’s just me, and perhaps it’s just that I’ve been in grad school, but I found that I never preferred to be woken up before I really needed to be up. I did not notice any benefit from being woken up when I started to move instead of when I had just enough time to get ready for school. Luckily, you can set it for “normal alarm clock mode” with no “wake-up phase.”

Still, Sleep Cycle is cool for a couple of reasons. First, It tracks how much time I give myself for sleeping. It starts counting when you set the alarm at night and stops when you wake up and keeps track. That’s how I know, for example, that I gave myself an average of 8 hours and 35 minutes to sleep in for the 155 nights before Reanna moved to Eugene. (It doesn’t work with two people in bed.) (And that included my last 125 days of grad school–not too bad!) That means I averaged fairly close to eight hours of sleep a night, with an estimated average sleep latency of 30 minutes. And that brings me to the coolest part.

As a chronic, intermittent insomniac, I’ve always wanted to know how long it actually takes me to get to sleep. Now I have a pretty good idea, thanks to Sleep Cycle. Many of my graphs look something like this:

I started trying to sleep just after 1 AM and drifted off around 1:45. I probably would have told you that I lay awake for at least an hour. Here’s another:

That looks like about an hour of insomnia. Don’t be fooled by the little initial drop–that was me lying very still, trying to sleep, before starting to toss and turn.

To finish off, here are a few other graphs, just so you can see some of the variety:

I am in a long, slow recovery from a sacroiliac joint sprain. I’ve just started being able to do more exercise than mild physiotherapy exercises, after almost nine months. I have to be careful, but I can do it. I am in the worst shape of my life, and generally I dislike it. The one nice thing, though, is how little I have to work to reach an aerobic heart rate.

In my normal shape, for example, bicycling is not a good choice for an aerobic workout. I have to push uncomfortably hard just to get to my minimum, low-level aerobic heart rate. [Which is somewhere around 108 beats per minute–60% of an estimated maximum of 180, since I can’t yet push hard enough to discover what my actual max is.] Now I can hop on my bike and hit an aerobic zone within a minute of riding gently. Pretty nice!

I’ve often wished I had a biofeedback device that could tell me whether something I was doing was good, bad, or neutral for my body. I have found pain and other sensations ambiguous directors. What are they asking for? This has been especially important in the last few years, dealing with injuries and slower healing. I recently asked my physiotherapist, Shannon, for her general recommendations for reading pain related to an activity. This is what she said:

1) Joint pain is never okay. If you experience joint pain during or after activity something is wrong; consider getting help to figure out what.

2) You should have no muscle pain during an activity (if you do, it means you are doing way too much).

3) Muscle pain after an activity means you are close to the right intensity – try lowering intensity and/or duration for a while and see how you respond.

4) Mild to moderate muscle pain in the next couple days is fine as long as it doesn’t escalate.

5) Each time you add an activity, do it at a constant level for 1-2 weeks before increasing duration or intensity

When your partner in a relationship stonewalls, what does it look like? They might leave the room or house. They may stop talking and ignore you. If they are an accomplished stonewaller, they probably look like they don’t care, are calm and unaffected. They look like “You could stand there screaming all day and I wouldn’t bat an eyelash.”

The first thing to know about this behavior is that, if it happens very often, your relationship is likely in trouble. You probably needed couples counseling years ago.

That is pretty common knowledge these days, now that John Gottman’s work is so well known. What I found surprising about stonewallers when I read his work is that if you hook a stonewaller up to a biofeedback machine like a heart-rate monitor, you find out that they are freaking out inside. Their heart rate and blood pressure are way up. They just look calm or withdrawn. They are actually so painfully engaged that they can’t deal with it. This knowledge has helped me think more clearly about stonewallers. I can be a lot more sympathetic to someone I know to be in something like flight-fight-freeze mode than someone who appears to be shutting me out.