Optimize Brain Performance with Exercise
We know that exercise is medicine.
Since 450 B.C. physical activity has been known to prevent chronic disease, with the saying "if there is a deficiency in food and exercise the body will fall sick" being attributed to Hippocrates! Modern literature is confirming that when we exercise all sorts of amazing things happen that go far beyond making our bodies look differently in the mirror.
For example, did you know that during exercise?....
Your skeletal muscles release a protein (Cathepsin B) that not only correlates with fitness, but also your memory and brain function.
Your bones release a protein hormone (osteocalcin) that increases Interleukin-6 (IL-6) to help your muscles take up glucose, help your liver release glucose, and help your adipocytes (fat cells) release fats all for optimizing energy consumption.
Sympathetic nervous system activation and IL-6 release also helps Natural Killer (NK) Cells redistribute to tumors which helps suppress tumor growth.
BDNF and AMPK also release with exercise and help protect the retinal cells in your eyes. The BDNF released is also implicated in neuroplasticity (e.g. memory and brain function).
We know that exercise is also particularly good for brain health and performance.
We can tell, from the fancy chair and suit indicating success, that this little fella has a solid aerobic capacity. (I hope you can all tell that I’m kidding.)
We know that there is a pretty linear relationship, in children, between aerobic capacity and mathematic and reading achievement (i.e. the better shape the kid is in, the better they typically do in math and reading).
We know that older adults who exercise absolutely dominate their control counterparts in executive, controlled, spatial, and speed tasks.
With benefits of exercise on brain demonstrated throughout the lifespan, who wouldn't want to exercise in a way that helps brain performance?
So, how do we capitalize on exercise to maximize our brain's health and performance?
Dr. Kenneth Jay presented on this very question at the International Symposium of Clinical Neuroscience 2018, and he started with the question…
Is Strength a Motor Skill?
We know that plastic changes and cortical excitability of the primary motor cortex (M1) increase during motor learning tasks, but we don't really see changes occur with non-learning tasks.
If resistance training requires refinement of muscle recruitment patterns, which is a form of motor learning, then can strength training be used to increase neuroplasticity and cortical excitability?
In other words...
Does strength training induce cortical reorganization similarly to motor learning?
A study by Jensen et al. 2005 looked at motor learning vs strength training to see what sort of cortical changes occurred in each group. The groups included:
Strength Training - 5sets of 6-10reps with 2min rest
Motor Learning (using visual feedback to visualize movement of objects) - 4 sets of 4min with 1min rest
Control Group - Chilling out, maxing, and relaxing all cool 3 times per week for 4 weeks.
The results showed that there was actually decreased excitability of corticospinal pathways in the strength training group (6.5% to 3.8%) when compared to the increased excitability in the motor learning group (3.9% to 6.8%) who did not actually move weights.
Dr. Kenneth Jay summarized that changes in strength most likely occur at subcortical levels, and not necessarily from increased M1 neural drive. He notes that when this study's outcomes are compared with other studies, the data generally suggests that there is no evidence saying stronger muscles correlate with larger cortical representation in M1 (i.e. bigger brain).
It is likely that the best way to reorganize and grow M1 is through motor learning tasks that can be augmented with visual feedback and continually novel tasks.
What about exercise type and intensity?
It turns out that, just like most things in life, the middle path tends to be best with respect to intensity. This applies to both resistance and cardiovascular training.
And we're basing a lot of that assertion off of studies looking cerebral (brain) blood flow during exercise.
A brain that is readily receiving fresh blood is a brain that is receiving oxygen and nutrients, while removing metabolic wastes and byproducts. This is particularly important in the brain, as neurons are by no means anaerobic cells. Thus, a fresh and steady supply of oxygen is absolutely vital for brain performance.
Normally, blood flow is "laminar" and smooth. After we reach a high enough intensity, blood flow becomes rough and choppy (i.e. turbulent). Working at moderate intensities, keeps us below a perfusion pressure threshold for turbulent blood flow and at a level that maximizes blood flow through the brain.
Best aerobic exercise intensity levels:
50-60% of VO2max or 50-60% of HRR
When we are training at levels around 50-60% of our HRR we end up seeing quality blood flow through the brain, with the greatest increase of flow seen in the lateral prefrontal cortex (a region of the frontal lobe).
Best resistance training levels:
30-60% of 1RM; avoiding >70-80% 1RM
Resistance training intensities are all centered around percentage of your 1 rep maximum (1RM).
Once we start going greater than 60% 1RM, we start seeing decreases in brain oxygenation.
It should also be noted that "high intensity" resistance training is considered 80% 1RM and higher.
With all that said, we now have our general recommendation to avoid lifting at intensities higher than 70-80% 1RM if the goal for the workout that day is on targeting brain health and performance.
Note: There are 100%, undoubted, peer-reviewed benefits to aerobic training at intensities >60% HRR and lifting at intensities >70-80% 1RM (even in neurodegenerative conditions). This post is not saying to never perform exercises at higher intensities. The message is simply this - we see better, smooth blood flow through the brain at intensities <60% 1RM and VO2max, and we see decreased oxygenation of the brain at >60%. If you are working out with the hopes of increasing mental/cognitive performance, and lifting for a PR every time you hit the weights, then you are likely missing the boat.
The Big Picture - Best Exercise for Brain Health & Performance.
(I don’t get funding or kickbacks from Nike. But, if anyone from Nike is reading this, I’m open to it!)
Motor Skill Learning + Visuospatial Tasks
Try NEW activities. Get a little uncomfortable.
Challenge your balance and hand-eye - even challenge them at the same time!
Think activities like: Revolution In Motion (RevInMo), Rock Steady Boxing, Yoga/Tai Chi, etc..
Concurrent cardiovascular and strength training
Aerobic at 50-60% of VO2max (50-60% of HRR)
Strength at 30-60% of 1RM
Ideally 30-60min in duration
Perform cognitive stimulus (reaction/attention-switching tasks)
An example exercise strategy that is found in the Parkinson's Disease world, but is challenging to nearly everyone: Do one thing, say the opposite (e.g. Lunge with your left leg while saying "right"). Do this with a partner giving each other commands to add a reactive component (and to really mess with your buddy!).
Exercise 3-5days per week in this manner
Bonus points if you can also include these pieces in your routine:
Exercise in a socially engaging environment
Exercise outdoors if possible
Sleep 7-9hrs per night (No less than 7hrs)
Reference:
Febbraio, M. A. (2017). Exercise metabolism in 2016: health benefits of exercise—more than meets the eye!. Nature Reviews Endocrinology, 13(2), 72.
Jay, Kenneth MSc, PhD. "Hacking your brain performance with exercise: Are all types of exercise equal?" International Symposium of Clinical Neuroscience, 25 May 2018, Wyndham Orlando Resort International Drive, Orlando, Fl. Lecture.