Using Exercise to reduce stress — Research review and practical tips.

• “Today most people believe that exercise has positive effects on all aspects of health. In the last decade, exercise as a prescription for improved physical and psychological health, in particular, stress, has received increasing attention in the health field”

This is a really good example of how there is truth to the saying that “Academics are living in their own world”. The opening quote comes from a Canadian Master’s thesis on the subject of stress and exercise from 1991(!) but working out is still rarely seen as one of the staple solutions to lessen stress, almost 30 years after the quote was written.

While it might seem a bit boring to read about exercise and stress, you should know that this post will also include really exciting nuggets such as - A recommendation for a fruit to gift your scientist friends, a short dictionary to impress them, Nietzsche's secret exercise advice, nerdy details at the bottom and last but not least - an early main takeaway point so you can skip the rest!

Short and necessary nerd dictionary:

RCT (Randomized control trial)— People get randomly assigned into either a control group or experimental group

Meta-analysis — As the name would suggest, a study looking at other studies

ES (Effect size) — The size of the differences between two groups

The main takeaway is this: Exercise is most likely a good tool to help you to handle stress and anxiety, this goes for all kinds of people no matter their race, gender or age. All sources reviewed agree on this point.

The reason I am choosing to use the really non-convincing phrase “most likely” is because science does not prove things, it only provides evidence for or against.

So, what was being looked at in the covered literature is Stress, but since “stress” is just a word, and words can have different meanings, we need to know the meaning of “stress” in this specific case to understand what was actually looked at.

One meaning of stress is the changing of different bio-markers in the body, examples would be fluctuations in hormone levels and blood pressure. These both falls under the so-called stress-response and are examples of what was looked at in two of the included meta-analyses (5). Another meaning of stress is the self-estimated level of anxiety, and this was what was looked at in (3) and (6). The reason I chose to include both the biological and the psychological rather than one was simply that I believe it gives a more complete picture and, therefore, provides a more precise definition of stress.

That is all well and good, but why does exercise work you might be thinking.

See there is something called the cross-stressor adaptation hypothesis, and this is a respected and popular hypothesis within the field … and it would be the easiest thing for me to refer to here.

But the fact of the matter is that there is far from a consensus in the field as to why exercise is actually effective. There are several theories ranging from that you have something to get better at, that you lose your sense of self while doing it, that you socialize, that your release monoamines and other neurotransmitters, that you increase your blood flow to the brain, that you forget about your stress or that your endorphins interact with your central nervous systems — the aforementioned cross-stressor adaptation hypothesis falls under this one for example. But several scientists, including me (who is not a scientist), rather view it as a mixture of several or perhaps even all of these.

So, while these details behinds its workings are still unclear, almost everyone agrees that it works, and that it works well. View the nerdy details at the bottom for more in-depth on this, as well as the following section.

Scientists and their favorite fruit

That being said and done, I now feel that I have earned the freedom to engage in something that people writing about science on the internet who are not real scientists love. This is seemingly also the case for actual scientists when they write books about their field in the popular science genre.

What I will do is something cutely and innocently-named — Cherry-picking.

Wikipedia says: “The picker (that would be me) would be expected to only select the ripest and healthiest fruits. An observer (that would be you) who only sees the selected fruit may thus wrongly conclude that most, or even all, of the tree’s fruit are in a likewise good condition. This can also give a false impression of the quality of the fruit.”

From Wikipedias example, you should see why cherry-picking usually is a problem. So in this case, as in most cases, take whatever I will be referring to hereafter with a grain of salt. But remember, the main takeaway still stands and I will still be using respected scientific sources here. Therefore, the likelihood of there being merit to the following statements is also still quite high, but the caveat still felt needed.

Some rapid-fire cherries about exercise for stress:

Even more effective if you are more stressed (3)

Works as an active coping mechanism (4)

Works as a physiological buffer (4)

Acute tranquilizing effects that remain up to 24 hours (5)

Continuous routines that span over a long time provides more benefit (5)

Larger effects for sessions over 30 min than under (5)

Aerobic is most commonly used and seems to be most efficient (All sources)

The main thing is that you do it, not that you improve fitness (2)

Can lead up to HALF the amount of percieved stress(1)

Epidemiological data of 32229 participants. Caution: Epidemiological data can only tell us about correlation, not causation.

Increases overall focus, energy and mood (5)

Sure, nothing to do with stress per se, but it is not hard to see how better focus, energy, and mood could help out, right?

Practicalities

The so-called “Pareto principle”, also known as the 80/20 rule (that seems to show up pretty much all over everything everywhere) states that 80% of the effects come from 20% of the causes, and this is true for exercise in the case of stress reduction as well.

The 20%, in this case, would be:

Three times per week, 30 minutes per exercise bout at moderate intensity.

This is also what most of the studies looking at health benefits in the area, including most of the ones I used, recommend. This means investing roughly 3% of the total time you spend awake during a week, that is a really, really good investment for the returns it might entail. And yes, this 3 % includes the time for preparation and showers, so there is no real excuse not to do it.

Exercise falls under what writer Mark Manson in his great book “The subtle art of not giving a fuck” calls VCR questions, and he sais the answer to all these are the same:

“From the outside, the answer is simple: just shut up and do it. “

On one level, how to exercise is very much VCR question. To get the mental benefits and heck, even to get somewhat fit, all you need to do is exercise every other day, as simple as that.

Although, I feel like I at least have to add a few things…

The first and maybe also the most important thing is this:

The best workout is the one you will be most likely to actually do.

So, if you hate running on the treadmill, don’t run on the treadmill. If you hate lifting weights, don’t get a gym membership. If you hate yoga, don’t do yoga. If you love playing football, do that. If you love walking in nature, do that. You get the point I guess.

A few other tips:

If you have a specific goal that actually requires some thought, get a trainer that knows this specific thing well. Examples would be a Marathon, deadlifting double your body weight, “Klassikern” (if you are from Sweden) or an Ironman (if you are insane). And yes, there is no need to get help to do any of these, if you read up a lot you can manage it yourself for sure, but getting one means less stress, less risk of injury and less time spent doing nonsense, so get a trainer.

Find some way to get it into your daily life, bike to work or start walking to the supermarket instead of taking the care, the small things make a big difference.

Find someone to do it with, chances go way up of you actually doing it if you feel accountable to someone else, find someone at work to join you to the gym for 30 minutes over lunch, talk your partner into it or here is a crazy thought, get a trainer!

Remember that exercise does not have to be fancy or complex, a couple of push-ups and squats now and then in the office to break up the sitting.

If you have not been running a lot, don’t start running a lot! Start slow, like really slow, running is a great way of exercising but it is also notorious for the amount of injuries it causes, so be careful when you are ramping up the volume.

If you have not been going to the gym a lot, see the point above.

Great ways to start to exercise where the volume is not an issue is walking, biking and swimming! These are all pretty much risk-free, unless you go from zero to really crazy, so don’t.

Since I just realized I made it through this whole thing without involving any philosophy, I simply have to quote Nietsche for the last tip:

“We should consider every day lost on which we have not danced at least once.”

Something really important to mention before I leave is that IF you are suffering from what seems to be an actual mental disorder related to stress such as GAD, PTSD, Panic Disorder, Phobia, you should be talking to a mental health professional and not be reading stuff on the internet.

Nerdy details:

For those curious as to why I chose to include the animal study (6): A good thing with including animals studies, is that it serves to lessen some of the potential risks to validity that experiments on humans always entails. Two primary examples of such risks would be:

1 — “Volunteer bias” which could be said to be a sub-type of “Self-selection bias” and is an example of when certain types of traits are more or less pronounced in the study sample compared to the general population. This bias may entail risking that the studies are non-generalizable to some degree.

2 — “Expectancy bias” is when the scientists unconsciously or even consciously influence the participants in some way. This, as you guessed might result in skewed results in some direction.

Nerdier yet important details that you can skip if you like:

The actual effect sizes of the included studies were the following: ES -0.31 out of 1,252 (95% CI) participants using only RCTs looking at anxiety (7), ES -0.48 out of 3,566 (95% CI) participants looking at bio-markers (6), ES -0.38 out of 10,755 (95% CI) participants using only RCTs looking at anxiety (2), ES -0.33 out of 462 (95% CI) animals using only RCTs looking at bio-markers (6).

I would feel bad for not mentioning the old Master’s Thesis, keeping in mind its more lose inclusion criteria making it less of a big deal than the others, it reports significant findings with an ES at -0.57 for exercise as a stress reducer. (3)

Even nerdier details that you probably should skip:

The Meta-analysis (7) was included in the Meta-meta analysis (2), but (7) was still included since it uses a better method for weighting for the previously mentioned publication bias. Although the Meta-meta analysis used something called funnel plots, that is a less precise method to check for publication bias. So the reason that I kept the smaller meta (7) as a stand-alone was because it is more precise, and the inclusion of the Meta-meta was because due to its huge sample giving a better overview. And in hindsight, the Meta-meta not showing much difference from the more strict ones when it comes to its ES, it most likely has high reliability even with the use of funnel plots.

Sources:

1: Aldana, S. G., Sutton, L. D., Jacobson, B. H., & Quirk, M. G. (1996). Relationships between Leisure Time Physical Activity and Perceived Stress. Perceptual and Motor Skills, 82(1), 315–321.

2: Rebar, A. L., Stanton, R., Geard, D., Short, C., Duncan, M. J., & Vandelanotte, C. (2015). A meta-meta-analysis of the effect of physical activity on depression and anxiety in non-clinical adult populations. Health Psychology Review, 9(3), 366–378.

3: Rosemary van Stravel (1991) Effects of execise on stress: a meta-analysis.

4: Sharon-David, H., & Tenenbaum, G. The Effectiveness of Exercise Interventions on Coping with Stress: Research Synthesis. Studies in Sport Humanities, 22.

5: Weinberg, R. S., & Gould, D. (2011). Foundations of sport and exercise psychology (5th ed.). Human Kinetics, 395–415.

6: Wipfli, B. M., & Ramirez, E. (2013). Stress reactivity in humans and animals: two meta-analyses. International Journal of Exercise Science, 6(2), 7.

7: Wipfli, B. M., Rethorst, C. D., & Landers, D. M. (2008). The Anxiolytic Effects of Exercise: A Meta-Analysis of Randomized Trials and Dose-Response Analysis. Journal of Sport and Exercise Psychology, 30(4), 392–410.