Our Brains on the Run

It’s old news that moderate to intense exercise is good for our hearts, muscles. skeleton, and lungs.  Running is particularly good since it’s weight-bearing and stresses the joints.  Some feel that creates wear and tear.  But the research is clear that running combined with strength-training, stretching, adequate rest and recovery, and a reasonable training load, in most people builds cartilage at joint surfaces rather than wearing it away.  This is due, in part, to nutrients being drawn into our joint capsules from physical activity.  Otherwise, the avascular (no blood vessels) cartilage is left to fend for itself and it’s not a fair fight.  So, for the most part, us runners feel we’re doing what we can to keep the chassis in decent shape, hoping to keep it on the road more than in the garage.  Whether or not we’ve come completely to terms with slowing down, we are at least out there putting in a good effort.

That is all well and good, but lurking in many people’s minds, literally, is what is going on in our heads, in our brains. We may have instances of forgetting things and not being as quick on the fly in spirited conversations.  We can live with that.  But one would have to be under a rock not to be aware of the dramatic increase in dementia and Alzheimer’s disease (AD) in the aging population. And it is frankly frightening to think about losing our ability to mentally function.

Let’s look at what the research is telling us. The American College of Sports Medicine published a paper in October 2018 entitled Exercise Protective Effects on the Brain.  The article noted that without consistent, moderately intense exercise, there is a body-wide increase in low-grade inflammation as we age.  There are several mechanisms in play, but one key effect is that inflammation reduces circulation to the brain, which in turn results in brain cell death. This is tantamount to brain aging.  The article also cites evidence of aging correlated with decreased neurotrophins (growth factors that affect brain function, including neurogenesis – new brain cell development) and cerebral blood flow.  While the brain only accounts for 2% of bodyweight, it uses about 25% of our energy.  Importantly, unlike muscles it has no energy reserves – it draws in real time!  So, it’s no surprise that elevating our heart rate results in more blood flowing to the brain.  No wonder we can have eureka moments while on the run!  To boot, without exercise, overall total brain size decreases, in particular the hippocampus, the site of memory function.  Another factor that also seems to negatively impact brain function is decreased sleep quality.

So, that’s the bad news.  However, there is good news: the research shows vigorous exercise, (with running, the weight-bearing beast, near the top of the list!) can mitigate, reverse, and at least hold at bay these impacts.  In addition, research indicates vigorous exercise helps us sleep better as well as increase memory, attention, and overall executive function.

We probably don’t really need more reasons to run than we already have.  I venture that most of us find time to run due to intrinsic benefits observed in our daily lives.  But it doesn’t hurt to know there are clinical reasons why we feel good, not only when we run but also in the hours that follow.  If our brain could talk (and maybe it does to some of you!) it would thank us for lacing up and taking them with us on those heady runs!             

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