Running: Mechanical Stress vs. Feel-Good Hormones

After taking AP Chemistry in High School, I opted for taking a regents Physics course.  I was scared of calculus, and thought I’d still learn a ton of physics without all of the horrifying math.  I was wrong; 11th grade Harold, you are a shitty planner.  Despite this, I always focused on a relating what we were learning to what I observed in my daily life.  There were now explanations.

One of the most mesmerizing things we see, a pendulum, is demystified with trigonometric functions.  However, we still tend to look at how far the pendulum swings, and forget that there is an equilibrium position that it wants to find.


When it comes to cardiovascular intensity, exercise physiologists, the fitness industry, and culture as a whole seems to do a godawful job of finding that equilibrium position.  By “godawful”, I mean we’re really shitty at it.  It seems to be that we’re accepting of 50 mile ultramarathons or 2.9 second, 345% VO2 max high efficiency interval workouts, and anything in between is invisible, stupid, or useless.

Even my post last week which discussed how very few people who run treadmill “sprints” are actually sprinting may have seemed like a pitch against HIIT, or sprinting semantics, depending on how you take it.  Let’s clarify.

Is maximal intensity sprint work good for you?  Yes.Is low-intensity, sustained aerobic work good for you?  Yes.Which one is better for you?  Yes.

Asking about “best” is missing the point, especially because the answer changes based on the goals.  What’s best for fat loss?  Interval training.  Want to run a marathon?  Better get your miles in.  What’s better for sports performance?  It depends on the sport.

A better question to ask is, What is more appropriate for the user?

It’s common practice that those with weight loss or body composition goals turn to cardio-based training for their fat loss goals.  There problem is, that newbie runners need to make it past that ‘dip’, right?  That’s a tough one.  Most fail to realize their goals due to lack of results, lack of will power, or injury.  Not an easy combo to overcome.

Let’s take a quick look at a study from the Orthopaedic Journal of Sports Medicine, a 1 year follow up study that looked at Predictors of Running-Related Injuries Among 930 Novice Runners.  According to the authors, “The findings of this study suggest BMI >30 kg/m2… to be associated with increased risk of injury among novice runners.” If you want to read the full study, you can do so here.

If you’re running because your goal is weight loss, but being overweight is a predictor for injury, and injury will prevent you from running, and therefore losing weight…maybe running isn’t the answer to your weight loss.  In fact, we know that running isn’t the best option for weight loss, but we also know that for many people, it feels damn good.  At least for the brain.

Running Destroys My Knees
I made this one just for YOU.

A friend who’s in medical school recently send me a study from The Journal of Neuroscience which studied effects of running on the ventral hippocampus in sedentary and runner nice.  From the abstract:

Here, we investigated the effects of cold water stress on the hippocampus of sedentary and runner mice and found that while stress increases expression of the protein products of the immediate early genes c-fos and arc in new and mature granule neurons in sedentary mice, it has no such effect in runners. We further showed that running enhances local inhibitory mechanisms in the hippocampus, including increases in stress-induced activation of hippocampal interneurons, expression of vesicular GABA transporter (vGAT), and extracellular GABA release during cold water swim stress. Finally, blocking GABAA receptors in the ventral hippocampus, but not the dorsal hippocampus, with the antagonist bicuculline, reverses the anxiolytic effect of running. Together, these results suggest that running improves anxiety regulation by engaging local inhibitory mechanisms in the ventral hippocampus. [Emphasis added]

So, if you’re a mouse that is frequently dunked in cold water for the sake of creating a stress response, regular running will decrease the stress response.  Yay!

Sarcasm aside, it’s great that we’re learning more about underlying factors of anxiety reduction.  Hopefully this can be applied to human studies, and more people being physically active so that they can smile while they sweat.  My issue isn’t with mental health, it’s with potentially dangerous exercise strategies for the sake of mental health.

If you’re overweight, depressed, or anxious, and you engage in physical activity to feel better, but you get hurt… You’re not going to be moving forward, and perhaps you’ll move backwards.  Frequently this happens because we’re overzealous with our exericse, and go from a completely sedentary lifestyle to 60 minutes of ‘cardio’ on the daily, or jumping into P90X because your bro said it was a good idea.  We need to find the balance on that pendulum.

If you really want to max out efficiency, why not just go for a walk?

There aren’t many circumstances when physical activity is bad.  Most of us need more of it, and we know it.  Issues arise when we’re overzealous, start with too much, or don’t know where we’re starting from.  One does not simply walk into Mordor, but that’s exactly what we’re trying to do.

Rather than spontaneously deciding to join your bff’s for that couch-to-5k or the local mud run next weekend, first ensure that you won’t break yourself in the process.  Seek out a physical therapist or personal trainer that can do a movement assessment for you.  If not, check out the Self Movement Screen:

Confession of bias: I really hate running, both personally and professionally.  I find little enjoyment in going out for the casual jog and “pounding the pavement”.  I get bored, and it’s not conducive to my goals.   It’s also less effective than lifting, so as a coach and trainer, I work with very few people who need to go out and do steady state cardio to reach their goals or enhance performance.

We get stronger and faster.  We feel better.  When aerobic work is necessary, we strive to minimize impact as much as possible.  We walk, we swim, we bike.  We do this for our mental performance, so that we may squat and sprint for our physical performance.

So we beat on, boats against the current, borne back ceaselessly into the past.

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