I’m a cyclist and a PhD student, and I’ve noticed some patterns in the way that my exercise habits affect my productivity. I get a lot of data from every ride. While I’m riding, I measure heart rate and power, and if I’m outside, I also measure distance and speed. I’ve found that the total amount of energy that I produce, as measured by the power meter on my bike, is a useful metric for how I should expect to feel the rest of the day and the next day. In particular, if I generate between 800 kJ and 1000 kJ, I usually feel alert, but not worn out. If I do less, I feel like I’ve not had enough exercise, and I either feel restless or like my body is in lazy recovery mode. If I do more, I feel physically worn out enough that it’s hard to work for an extended period of time, especially on the days that I am working in the lab.
What I think is most curious about this is that it is relatively independent of my fitness or the intensity of the ride. If I go balls-out the whole time, it takes slightly fewer kJ to make it hard to focus, and if I go super easy, it takes a bit more. It’s the same with fitness. The difference between the power I can sustain for an hour when I’m in form for racing vs when I’ve barely been riding at all is about 25-30%, but the difference in the amount of mechanical work to make me unproductive is about 10%. (You might notice this gives me an incentive to stay in shape; I can do the same amount of work for the same productivity boost in less time when I’m more fit.)
So, what’s definitely true is that the amount of work I put in on the bike is a useful metric for maximizing my productivity. What’s unclear is if the amount of work is in some way fundamental to the mental state that it puts me in. The most obvious possibility is that it mainly has to do with the number of calories I burn; this is consistent with the finding that I need to do more work to feel tired when I’m more fit, since training will make you more efficient. But it’s not obvious to me why this would be the case. When I’m in poor shape, an 800 kJ ride will have a much more drastic effect on my blood sugar than it will when I’m fit enough to race. It would be useful to venture outside the 800-1000 kJ range on days when I need to get work done.
I don’t really know enough physiology to get any further than this. Does anybody else have experience with this sort of thing? Does anyone have empirically testable hypotheses? (Non-testable or not-testable-for-me hypotheses may be interesting as well.)
People like to think of their brains as some kind of separate regulating thing compared to the rest of their bodies. They’re not. Everything is mushed together in a common mileu and the sheer degree of crosstalk between your nervous system and everything else is enormous, through both the general chemical environment and fibers that have nothing to do with the consciously available senses.
Humans did not evolve sitting around writing theses. They evolved spending energy in an active way, possibly with wide variation from day to day. It is completely unsurprising to me that there is an amount of energy use that makes one feel clearer and more productive compared to the sedentary graduate student, and that that can vary from person to person and over time in the same person as their physiological state adapts and changes.
It is completely unsurprising to me that there is an amount of energy use that makes one feel clearer and more productive compared to the sedentary graduate student, and that that can vary from person to person and over time in the same person as their physiological state adapts and changes.
I don’t think that anybody here is surprised by this. What’s surprising is not that there is an amount of exercise that is required for me to feel alert and productive, it’s that the relationship between my mood and my exercise seems to follow a single, simple, specific rule. You explain the reasons why this should be surprising in your first paragraph. To illustrate why this seems surprisingly simple, here is a list of things that seem not to affect my productivity, holding total work constant:
The last three of these are metrics that are part of a physiological model. The model is somewhat simplistic, given the complexity of humans that you have mentioned, but the metrics have proven to be useful for athletic training (anyone who is interested in a more detailed description, which is still written for the layman, should check out Training and Racing with a Power Meter by Coggan and Allen). More to the point, there’s no particular reason (that I can see) to expect total work to win out over any of the other things on this list.
But I do notice two things, having actually written down this list. First, each of these does seem to have a small non-zero effect. As I already mentioned, doing a little more than 1000kJ over a longer duration does seem to be okay, and my FTP does seem to shift my ideal amount of work a bit. Second, these are tightly coupled to each other. You can boil duration, average power, total work, normalized power, TSS, and FTP down to four variables, one of which is total work, and another of which will usually be 90% determined by total work. Furthermore, fatigue and how much I eat will have an effect on how much of a work I’m able or willing to do on a given day. This all means that it would be very easy to mistake a more complex relationship between some or all of these factors and my mood/cognition as a simple one, especially a simple rule that is bent slightly by external factors. I feel like this eliminates much of the confusion for me (the lesson here being that when I’m confused, I should stop, write down my confusion, and stare at it). However, it does not offer a strategy for venturing too far from the 900kJ rule without consequence.
That’s some neat data and observation! Could there be other substantial moderating differences between the days when you generate ~900 kJ and the days when you don’t? (E.g., does your mental state before you ride affect how much energy you generate? This could suggest a different causal relationship.) If there are, maybe some of these effects can be removed if you independently randomize the energy you generate each time you ride, so that you don’t get to choose how much you ride.
To make this a single-blinded experiment, just wear a blindfold; to double blind, add a high-beam lamp to your bike; and to triple blind, equip and direct high beams both front and rear.
Could there be other substantial moderating differences between the days when you generate ~900 kJ and the days when you don’t? (E.g., does your mental state before you ride affect how much energy you generate?
This could be the case, or there could be a common cause between the total work I do and my mood for the day. What makes me think this is less likely is that, when I’m following a training plan, the total work for the ride is largely determined days or weeks ahead of time. Then again, I will modify the day’s workout on a training plan if I’m feeling shitty. Or it could just be that I noticed the pattern once when it happened by chance, then I expected it to continue, so it did (that is, it’s more of a placebo than anything else). Then again, it wouldn’t be hard for small effects like this to add up to the observed effect.
I actually did think about blinding it. I could modify some existing software to give me an intensity or duration that I don’t know ahead of time, and that I don’t have in front of me while I’m riding, and I could even not look at what it was until days or weeks later when I’m analyzing the results (or I could get even more hardcore and have someone else analyze it). The problem is that most of the motivation mechanisms I have for actually doing a worthwhile ride indoors require me to have access to a lot of this data. It would sort of be like trying to stay motivated in a game where you have no access to your score or whether you’ve eliminated another player.
I’m a cyclist and a PhD student, and I’ve noticed some patterns in the way that my exercise habits affect my productivity. I get a lot of data from every ride. While I’m riding, I measure heart rate and power, and if I’m outside, I also measure distance and speed. I’ve found that the total amount of energy that I produce, as measured by the power meter on my bike, is a useful metric for how I should expect to feel the rest of the day and the next day. In particular, if I generate between 800 kJ and 1000 kJ, I usually feel alert, but not worn out. If I do less, I feel like I’ve not had enough exercise, and I either feel restless or like my body is in lazy recovery mode. If I do more, I feel physically worn out enough that it’s hard to work for an extended period of time, especially on the days that I am working in the lab.
What I think is most curious about this is that it is relatively independent of my fitness or the intensity of the ride. If I go balls-out the whole time, it takes slightly fewer kJ to make it hard to focus, and if I go super easy, it takes a bit more. It’s the same with fitness. The difference between the power I can sustain for an hour when I’m in form for racing vs when I’ve barely been riding at all is about 25-30%, but the difference in the amount of mechanical work to make me unproductive is about 10%. (You might notice this gives me an incentive to stay in shape; I can do the same amount of work for the same productivity boost in less time when I’m more fit.)
So, what’s definitely true is that the amount of work I put in on the bike is a useful metric for maximizing my productivity. What’s unclear is if the amount of work is in some way fundamental to the mental state that it puts me in. The most obvious possibility is that it mainly has to do with the number of calories I burn; this is consistent with the finding that I need to do more work to feel tired when I’m more fit, since training will make you more efficient. But it’s not obvious to me why this would be the case. When I’m in poor shape, an 800 kJ ride will have a much more drastic effect on my blood sugar than it will when I’m fit enough to race. It would be useful to venture outside the 800-1000 kJ range on days when I need to get work done.
I don’t really know enough physiology to get any further than this. Does anybody else have experience with this sort of thing? Does anyone have empirically testable hypotheses? (Non-testable or not-testable-for-me hypotheses may be interesting as well.)
People like to think of their brains as some kind of separate regulating thing compared to the rest of their bodies. They’re not. Everything is mushed together in a common mileu and the sheer degree of crosstalk between your nervous system and everything else is enormous, through both the general chemical environment and fibers that have nothing to do with the consciously available senses.
Humans did not evolve sitting around writing theses. They evolved spending energy in an active way, possibly with wide variation from day to day. It is completely unsurprising to me that there is an amount of energy use that makes one feel clearer and more productive compared to the sedentary graduate student, and that that can vary from person to person and over time in the same person as their physiological state adapts and changes.
I don’t think that anybody here is surprised by this. What’s surprising is not that there is an amount of exercise that is required for me to feel alert and productive, it’s that the relationship between my mood and my exercise seems to follow a single, simple, specific rule. You explain the reasons why this should be surprising in your first paragraph. To illustrate why this seems surprisingly simple, here is a list of things that seem not to affect my productivity, holding total work constant:
-Heart rate
-Duration
-Time of day
-Eating before or during the ride*
-How fatigued I am from the day before**
-Average Power
-Normalized power
-My functional threshold power at the time (a measure of fitness)
-”Training Stress Score”
The last three of these are metrics that are part of a physiological model. The model is somewhat simplistic, given the complexity of humans that you have mentioned, but the metrics have proven to be useful for athletic training (anyone who is interested in a more detailed description, which is still written for the layman, should check out Training and Racing with a Power Meter by Coggan and Allen). More to the point, there’s no particular reason (that I can see) to expect total work to win out over any of the other things on this list.
But I do notice two things, having actually written down this list. First, each of these does seem to have a small non-zero effect. As I already mentioned, doing a little more than 1000kJ over a longer duration does seem to be okay, and my FTP does seem to shift my ideal amount of work a bit. Second, these are tightly coupled to each other. You can boil duration, average power, total work, normalized power, TSS, and FTP down to four variables, one of which is total work, and another of which will usually be 90% determined by total work. Furthermore, fatigue and how much I eat will have an effect on how much of a work I’m able or willing to do on a given day. This all means that it would be very easy to mistake a more complex relationship between some or all of these factors and my mood/cognition as a simple one, especially a simple rule that is bent slightly by external factors. I feel like this eliminates much of the confusion for me (the lesson here being that when I’m confused, I should stop, write down my confusion, and stare at it). However, it does not offer a strategy for venturing too far from the 900kJ rule without consequence.
That’s some neat data and observation! Could there be other substantial moderating differences between the days when you generate ~900 kJ and the days when you don’t? (E.g., does your mental state before you ride affect how much energy you generate? This could suggest a different causal relationship.) If there are, maybe some of these effects can be removed if you independently randomize the energy you generate each time you ride, so that you don’t get to choose how much you ride.
To make this a single-blinded experiment, just wear a blindfold; to double blind, add a high-beam lamp to your bike; and to triple blind, equip and direct high beams both front and rear.
… okay, there will be no blinding.
This could be the case, or there could be a common cause between the total work I do and my mood for the day. What makes me think this is less likely is that, when I’m following a training plan, the total work for the ride is largely determined days or weeks ahead of time. Then again, I will modify the day’s workout on a training plan if I’m feeling shitty. Or it could just be that I noticed the pattern once when it happened by chance, then I expected it to continue, so it did (that is, it’s more of a placebo than anything else). Then again, it wouldn’t be hard for small effects like this to add up to the observed effect.
I actually did think about blinding it. I could modify some existing software to give me an intensity or duration that I don’t know ahead of time, and that I don’t have in front of me while I’m riding, and I could even not look at what it was until days or weeks later when I’m analyzing the results (or I could get even more hardcore and have someone else analyze it). The problem is that most of the motivation mechanisms I have for actually doing a worthwhile ride indoors require me to have access to a lot of this data. It would sort of be like trying to stay motivated in a game where you have no access to your score or whether you’ve eliminated another player.