The consequences of physical inactivity are far-reaching. Some reports suggest that the health risk associated with lack of frequent and moderate exercise are comparable with that of smoking, obesity, and hypertension. It will even shorten your lifespan (1). But this is not new information. Most people have known this for years, if not decades. However, within the last 15 years, another area of research in exercise science has slowly emerged and is just now gaining traction and attention outside the research- and clinical communities.
“Walking is man’s best medicine”
- Hippocrates, circa 450 BCE.
In 1999, van Praag et al published the first key findings in the effects of exercise on brain function – in mice. A well-designed study revealed that running, but interestingly neither swimming or being subjected to enriched-learning environments, increased cell proliferation and neurogenesis in the dentate gyrus (a part of the brain essential for the formation of memories), found by staining with Bromodeoxyuridine (brdU) (2).
Fast forward to present day, and the combined research community investigating the effects of exercise-enhanced neuroplasticity now shows that up-regulation of growth factors, such as Brain-Derived Neurotrophic Factor (BDNF), greatly enhances neurogenesis in the hippocampi of both rodents and human beings.
Indeed, aerobic exercise may be one of the best alternatives to Bradley Cooper's NZT (from the movie “Limitless”), having tremendous potential for boosted cognitive development in both children and adults.
But there is more to exercise and the effects on the brain than what meets the eye. For instance, it is now known that BDNF proliferation can be facilitated by a secretory protein called "myokine cathepsin B", which is secreted from contracting skeletal muscle (“myo”, meaning muscle) (3). Further, a study by Chrysostomou et al. (2016) showed that the age-related vulnerability of retinal ganglion cells in the eye can be reversed by being physically active, as retinal ganglion cells undergo an increase in intra-ocular pressure, which in turn preserves inner retinal synapses (4).
There is no doubt that aerobic exercise has an almost limitless potential (without the side effects of NZT).
The question remaining to be answered is: “Is there one type of exercise that is superior to all?”, because up until recently, the type of exercise studied has primarily been typical cardiovascular activities (e.g. running or cycling).
With the emergence of cross-over gym activities (e.g. Crossfit) and the abundance of other training modalities available to the public, people are now attending strength training classes, dance- and yoga classes, while still joining in on a spinning class or, for those seeking the extreme, strength-cardio hybrid races such as Tough Mudder or Evolution Race.
Many good biomechanical and musculoskeletal arguments exist for tackling both strength-power training and cardiovascular exercise if you want to beat the odds and live a long and healthy life. But what kind of impact do these activities have on brain function?
Science to the rescue!
Bossers et al (2015) showed that a combination of aerobic and strength training is more effective than aerobic-only training in slowing cognitive- and motor decline in patients with dementia (5). Similarly, Teresa Liu-Ambrose et al (2010) showed in a 12-month long randomized controlled trial that resistance training with a frequency of just 1-2 sessions per week improved the executive cognitive function of selective attention and conflict resolution among senior women (6).
What could be a possible explanation for the effects of strength training on the brain?
Strength training triggers the release of a molecule called Insulin-like growth factor-1 (IGF-1). IGF-1 is a growth hormone produced in the liver. It affects the communication between brain cells and increases both neuronal and blood vessel proliferation.
These are just examples of the findings of resistance training on brain health and performance and collectively it seems like different modes of exercise benefit different areas of the brain. Another example of this is related to the intensity of exercise. Where most research in aerobic exercise and brain function has been moderate intensity (e.g. ~70% of maximal oxygen uptake) but what about high-intensity interval training (HIIT) and the brain?
Sim et al (2015) found that HIIT attenuates leisure caloric intake (7). This can be explained by lower levels of the “hunger” hormone ghrelin that is responsible for signaling the “eating control center” in the hypothalamus to start eating. Lower levels of ghrelin mean that the eating control center is kept at bay resulting in a lower caloric intake. This can at least partly explain why people who do a lot of HIIT usually also are quite fit with normal BMI.
Another aspect of exercise is coordination training and motor learning. Sports-like activities (balancing, synchronizing arm and leg movements, and manipulating objects like ropes and balls) have been shown by Neimann et al (2014) to have a greater impact on basal ganglia volume (caudate and globus pallidus) and executive function compared with typical cardiovascular exercise (8). Similarly, Voelcker-Rehage et al (2011) found that coordination training is associated with increased activation in the visual–spatial network whereas cardiovascular training is associated with increased activation of the sensorimotor network (9).
Collectively, the recent advances in neuroscience and exercise clearly indicate that different types and modes of exercise have different effects and target areas in the brain.
The single-factor mindset of having one superior type of exercise or one physical activity seems outdated, and benefits can be found in a variety of activities. It’s not a question of doing “this” vs. “that” but rather a question of doing “both” when improving brain function and performance.
1. Exercise and well-being: a review of mental and physical... : Current Opinion in Psychiatry [Internet]. LWW. [cited 2017 Jul 4]. Available from: http://journals.lww.com/co-psychiatry/Fulltext/2005/03000/Exercise_and_well_being__a_review_of_mental_and.13.aspx
2. van Praag H, Kempermann G, Gage FH. Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. Nat Neurosci. 1999 Mar;2(3):266–70.
3. Moon HY, Becke A, Berron D, Becker B, Sah N, Benoni G, et al. Running-Induced Systemic Cathepsin B Secretion Is Associated with Memory Function. Cell Metab. 2016 Aug 9;24(2):332–40.
4. Chrysostomou V, Galic S, van Wijngaarden P, Trounce IA, Steinberg GR, Crowston JG. Exercise reverses age-related vulnerability of the retina to injury by preventing complement-mediated synapse elimination via a BDNF-dependent pathway. Aging Cell. 2016 Sep 9;
5. Bossers WJR, van der Woude LHV, Boersma F, Hortobágyi T, Scherder EJA, van Heuvelen MJG. A 9-Week Aerobic and Strength Training Program Improves Cognitive and Motor Function in Patients with Dementia: A Randomized, Controlled Trial. Am J Geriatr Psychiatry Off J Am Assoc Geriatr Psychiatry. 2015 Nov;23(11):1106–16.
6. Liu-Ambrose T, Nagamatsu LS, Graf P, Beattie BL, Ashe MC, Handy TC. Resistance Training and Executive Functions: A 12-Month Randomised Controlled Trial. Arch Intern Med. 2010 Jan 25;170(2):170–8.
7. Sim AY, Wallman KE, Fairchild TJ, Guelfi KJ. High-intensity intermittent exercise attenuates ad-libitum energy intake. Int J Obes 2005. 2014 Mar;38(3):417–22.
8. Niemann C, Godde B, Staudinger UM, Voelcker-Rehage C. Exercise-induced changes in basal ganglia volume and cognition in older adults. Neuroscience. 2014 Dec 5;281:147–63.
9. Voelcker-Rehage C, Godde B, Staudinger UM. Cardiovascular and Coordination Training Differentially Improve Cognitive Performance and Neural Processing in Older Adults. Front Hum Neurosci [Internet]. 2011 Mar 17 [cited 2017 Jul 4];5. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3062100/
Dr. Kenneth Jay holds a Master's degree in exercise physiology with a specialty in cardiovascular function and a PhD in Sports Science and Clinical Biomechanics. He is a researcher based in Denmark and an adjunct professor of Human Performance and Clinical Biomechanics at the Carrick Institute in Orlando, Florida. With +20 years of experience in the fitness industry and more than a decade of consulting experience for international and Olympic level athletes, Kenneth Jay has instructed a coached some of the best. In 2014 Kenneth Jay authored the Cardio Code book and created the [cardio]CODE and [kinetic]CODE certification courses. With a deep interest in the the link between the body and brain, Kenneth Jay is specialized in a neuro-physio-biomechanical approach to health and performance enhancement.