Hey, Maybe You’re Just Tired
On Mental and Physical Fatigue
Photo by Marco Bianchetti on Unsplash
You’re blasted out of the ether realm of sleep by the intrusive alarm that may as well be tiny blacksmiths using your ear drums as anvils.
Goodbye, Darkness, my old friend, and Hello to a day of feeling bleh and meh.
Grogginess. Sluggishness. A day of general malaise. All the result of a single night of inadequate sleep, or it could have been adequate, but we may have been running a sleep deficit, so a single night of usual sleep isn’t enough.
We’ve all been there, and hopefully these nights and days are the minority rather than the majority. How we feel, this is pure fatigue, and it’s a nice combo of physical and mental fatigue, each of which can have pretty negative effects on every other area of life.
All of this is obvious. No one’s going to argue about the necessity, benefits, and virtues of regular adequate sleep.
What’s not always obvious are the other ways that we can accumulate fatigue and how fatigue can affect us.
Though we know it when we experience it, fatigue is kind of an abstract concept and difficult to communicate with specifics, but there is, of course, physical fatigue, mental fatigue, and combos, so here are some definitions in the literature:
Physiologically,
“Fatigue’’ is a term used to describe a decrease in physical performance associated with an increase in the real/perceived difficulty of a task or exercise. From another aspect, fatigue is defined as the inability of the muscles to maintain the required level of strength during exercises. Alternatively, it can be defined as an exercise induced reduction in muscle’s capability to generate force. The term muscle fatigue was used to denote a transient decrease in the muscle capacity to perform physical activity. Performing a motor task for long periods induces motor fatigue, which is generally accepted as a decline in a person’s ability to exert force [1].
This physiological fatigue, as noted, is transient, a temporary reduction in the muscles’ ability to generate force, much like the result of exercise. You’re aware of this fatigue. It might result in soreness, and it appears after doing physical work, work that you’re quite aware of having done, again, like working out or yard work.
Another, more general manifestation:
Fatigue has been defined as an overwhelming, debilitating, and sustained sense of exhaustion that decreases the ability to function and carry out daily activities. Up to 45% of the U.S. population has reported experiencing fatigue, which greatly reduces overall quality of life [2].
And then there’s mental fatigue, which is “a psychobiological state caused by prolonged periods of demanding cognitive activity” [3], one “that impairs cognitive as well as physical performance in different settings” [4].
In the sports literature and fitness space, there are also the well-known and discussed concepts of systemic and accumulated fatigue.
Systemic fatigue is like whole body fatigue, which is not so much muscular fatigue but more like central nervous system (CNS) fatigue, which can be produced from doing a lot of physical work. For example, if you were to run a marathon today, you can bet you’d have systemic fatigue tomorrow and for the several following days. Similarly, any compound exercise when weightlifting, like squats and deadlifts, is famous for the systemic fatigue it can generate (but that really depends on volume load—how many reps and sets with a given amount of weight you do in a given session).
Systemic fatigue usually requires at least a couple of days to dissipate. Again, if you were to run a marathon today, when would you be recovered well enough to do it again? The same is true for squats and deadlifts, and most other activities. When would you be able to do the same amount of work or more again?
Accumulated physical fatigue is when we don’t rest completely and adequately between training sessions. It’s like there’s a fractional remainder of fatigue, and if this is the trend, each training session will put a drop in that bucket, and at some point, we’ll need to really pull things back so that we can recover. Otherwise, we’re grinding ourselves into the ground.
Accumulated and systemic fatigue certainly affect how we feel. At first, we like it, but after a while, it starts adding to mental fatigue.
On mental fatigue, there are also many contributors. Cognitively demanding work is acutely fatiguing mentally, and doing cognitively demanding work routinely can generate accumulated mental fatigue just like we can do the same thing physically with physically demanding work. Other contributors to mental fatigue include typical life stressors: work, relationships, finances, childcare, even commuting.
In sports literature, there is a subgenre that focuses on mental fatigue on sport performance. Often, these studies will induce acute mental fatigue in either one or two ways; one is a computer-based cognitive test and the other, more applicable—ecologically valid, as they say—is through phone and social media usage. Even 30 minutes of social media scrolling prior to a training session is enough to generate mental fatigue that has observable effects on endurance performance [5], weightlifting performance [6], and sport performance [7].
These researchers have participants subjectively rate their mental fatigue prior to and after using social media. Acute mental fatigue is reliably greater after social media, let’s call it, exposure than control conditions, which leads to greater ratings of perceived exertion (RPE), lower motivation, and in the case of sport performance, leads to a degradation of technical skills.
These studies also note how athletes with accumulated, long-term mental fatigue also tend to have decreased emotional control, lower quality choices in food and nutrition, as well as disengagement, withdrawal, reduced enthusiasm, and also require longer time to make decisions in gameplay and increase their errors.
All of this sounds like depression, doesn’t it?
Another thing that increases mental fatigue is anyone in energy restriction, you know, dieting.
There’s a lot we can learn from these studies on athletes, and we don’t have to be athletes to experience all this fatigue: physical, mental, accumulative, systemic, and long-term fatigue. Athletes just generate and accumulate fatigue much more quickly—training sessions for skills, endurance, power, and strength, gameplay, travel, spectator and media scrutiny and criticism, all on top of the same other stressors we all endure—but they are metaphors for all of us.
The first thing is to be able to recognize fatigue, in whichever form or forms it manifests itself.
When we’re talking about doing work—any kind, physical or cognitive—we must recognize that doing that work is going to generate fatigue, and that fatigue will be proportional to volume and intensity of the work. Then, we must recover from it.
If you’re like me and have period of intense work from your job, work from life obligations, have periods of intense study, workout routinely, and then run diets from time to time, it’s easy to build up all these different forms of fatigue into something like a super-organism.
When we find ourselves in these periods, we must have periods that are less demanding so that we can dissipate the fatigue. Like physical activity, the recovery time should be proportional to the intensity and volume of work done. When people go on vacation and holiday, sometimes they just crash, but vacation is not always a practical or viable solution, and we shouldn’t let it get to the point where we crash.
Sometimes I have similar conversations with students, and I’ll use physical activity as a metaphor. If you were going to run a marathon tomorrow, how would you prepare? I bet that you would not run a marathon today. And then how would you recover the day after? I bet that it would not be by running another one.
Some acute ways to combat fatigue, according to the authors of the fourth footnote, are caffeine, music, and other extrinsic motivations, that is, rewards, something like a treat, either a literal snack, meal, or something else that is a self-gift. Funny enough, these are also used as ergogenic aids in sport—things to get us pumped and going—but they only last for a short period.
(Just today I tried to get a diet soda from a vending machine—something I rarely do—and the little motorized cup that takes the soda from the inventory dropped the soda to the body of the machine instead of the dispenser receptable. Oh, well. I tried to treat myself.)
Some other ways to manage, reduce, and combat fatigue are to periodize—or block—our work periods with periods of rest and recovery, whatever that looks like for you. If you can afford it, consider taking a day off and sleep in. If you can’t, maybe treat yourself to a movie. Get together with some friends. Dedicate some time to activities and hobbies you want to do—not chores or home repairs (more work). Even getting to bed earlier can work wonders.
Fatigue is a Hydra, and we may not be able to permanently slay it, but we can’t definitely keep it down to only a couple of heads at any given time, but we should remember that there will be periods where there are more heads than we can handle before too long, and we’ll have to respond accordingly. It’s temporary, and we’ll recover if we remember to make it a priority.
Regarding health and fitness goals, success comes down to one thing: long-term consistency and adherence.
That’s it.
Even when you think things are not working, they are, most likely, but they are just moving slower than you want or that is meaningfully perceivable.
And the blips, disruptions, and inconsistencies don’t have to be total train wrecks in order to have effects on your progress. These can be little things that stack up, like accumulated fatigue, which is essentially a death by a thousand cuts.
We can’t expect to have any long-term success in any endeavor if we feel like we’re trudging through mud and sludge.
So, if you’re not meeting your goals, if you’re having difficulty focusing, if you feel yourself down, withdrawing, unenthused, and unmotivated, if you feel like everything is harder, and you’re working as hard as usual, or more, but your efforts aren’t paying off, the answer might be right in front of you.
Hey, maybe, just maybe, you’re tired.
