Newsletter Article

Impact of physical activity on adolescent memory and brain development

January 2018

Involvement in sports and regular physical activity during the teenage years can have a measurable impact on social development and mental health during this stage of life. A study conducted in the Netherlands found that among 7000 students surveyed, aged 11 to 16, those who were involved in organized sports had greater self-esteem and a more positive self-image than those who were not physically active.[1] These adolescents were also less likely to engage in problematic behaviors such as social withdrawal and anxiety, getting into trouble, and aggressive behavior with others.

In another study, the attention capacity of teenage subjects was measured using the d2 Test of Attention, and accelerometer data was collected over 7 days.[2] The researchers compared the attention scores to the amount of time the subjects spent in MVPA in free-living conditions. The subjects’ attention capacity scores were significantly and positively associated with the amount of time they spent in moderate or moderate to vigorous physical activity. This demonstrates that spending more time in higher intensity activity could result in improved attentiveness in adolescents.

In additional to self-esteem and attention capacity, the amount of time spent in physical activity may also affect how the adolescent brain maps memories. A high-fit group (10 hours or greater of aerobic exercise per week) and a low-fit group (less than 1 hour of aerobic exercise per week) of teenagers viewed pairs of words in an fMRI scanner.[3] Twenty minutes later, they viewed the word pairs again and had to match the words that were previously presented together. The high-fit and low-fit groups did not perform differently, but the way their brains processed and searched for the memories was different. We make memories using the prefrontal cortex and hippocampus, during which time the other areas of the brain are deactivated. This is how the brains of the high-fit group reacted. In the low-fit group, the areas of the brain that should have deactivated during memory generation still showed activity, and greater resources were used in the hippocampus. It has been shown that higher-fit elderly seem to have greater memory recall than low-fit elderly, so the researchers theorize that the low-fit teens adapted to perform to their high-fit peers. Since their brains are still young and healthy, they are able to compensate without their memory being affected. However, these differences may affect their ability to create memories as they age.

Quinoa

Quinoa (pronounced KEEN-wah) may not be a household name in many parts of the world, but this “ancient grain” has actually been consumed for more than 5000 years by inhabitants of the Andes mountains and other parts of South America.[4] Quinoa is usually grouped with cereal grasses such as wheat, oats, and barley, but it is actually a seed in the same family as spinach, Swiss chard, and beets. Unlike most other grains, quinoa is surprisingly rich in nutrients. It contains high levels of lysine and isoleucine, making it a complete protein source.

Quinoa is also quite versatile. The seeds are most often boiled, but they can also be ground into flour and used for baking. Quinoa flour has a higher fat content than whole wheat flour, and includes heart healthy monounsaturated fats and omega-3 fatty acids. Because quinoa is gluten free, it makes a good wheat alternative for people with celiac disease or gluten sensitivity. Quinoa is also a very good source of manganese and a good source of phosphorus, copper, magnesium, fiber, folate, and zinc.

The most common type of quinoa found in stores is off-white in color, however red, black, and mixed varieties are also available. Before cooking quinoa, be sure to run water over the grains while rubbing them with your hands. This removes the saponins on the outer part of the seeds, which can have a bitter taste.

Quinoa Tabbouleh

Ingredients:
3 cups cooked white quinoa, cooled
1 1/2 cups flat-leaf parsley leaves
1 cup roughly chopped mint leaves
1/4 cup snipped chives
9 ounces cherry tomatoes, quartered
1 tbsp finely grate lemon zest
2 tbsp lemon juice
2 tbsp olive oil
Salt and freshly cracked black pepper
Feta, optional
Pitas, for serving, optional

Directions:
In a bowl, add quinoa, parsley, mint, chives, tomatoes and lemon zest and toss to combine. In a separate bowl, mix lemon juice, oil, salt and pepper; pour over salad and toss to combine. Top with crumbled feta and serve with pitas, if desired.

Recipe from http://www.health.com/health/recipe/0,,50400000137169,00.html/

Exercise and gut bacteria

It has been well documented that what we eat affects the flora in our stomach and intestines. In two recent studies, it has been shown that exercise may also affect the gut microbiota in both mice and human models. In the mice model, bacteria was transferred from either exercised or sedentary mice into germ-free, sedentary mice.[5] The mice that received the exercised mouse microbiota had a higher proportion of microbes that produced butyrate, a fatty acid that promotes healthy intestinal cells and reduces inflammation. These mice also became more resistant to ulcerative colitis.

In the human model, obese and lean subjects went through an aerobic exercise program for 6 weeks, followed by 6 weeks of sedentary behavior.[6] At the end of each 6 week period, the researchers took gut samples. After the subjects went through the exercise program, their intestinal butyrate levels increased. The obese subjects experienced a dramatic increase in butyrate producing microbes after the exercise program. After the 6-week sedentary period, both groups showed decreases in these microbes.

These studies show that, while eating habits are still extremely important, moderate changes in physical activity can cause significant changes in the health of your gut, resulting in both short-term and long-term benefits.

Health Matters is written by Lindsey Guthrie, MS, RD, LD/N and Tyler Guthrie, MS, CSCS.

References:

  1. Why Exercise May Do a Teenage Mind Good. NPR. https://www.npr.org/sections/health-shots/2013/01/07/168616995/why-exercise-may-do-a-teenage-mind-good
  2. Vanheist J, Beghin L, Duhamel A, et al. Physical Activity Is Associated with Attention Capacity in Adolescents. Journal of Pediatrics. 2016; 168: 126.
  3. Exercise Affects How the Teen Brain Encodes Memories. Cognitive Neuroscience Society. https://www.cogneurosociety.org/exercise_teenbrain/
  4. White DK, Gabriel KP, Kim Y, Lewis CE, Sternfeld B. Do Short Spurts of Physical Activity Benefit Cardiovascular Health? The CARDIA Study. Medicine and Science in Sports and Exercise. 2015; 47(11): 2353.
  5. Quinoa. The George Mateljan Foundation.http://whfoods.org/genpage.php?tname=foodspice&dbid=142#descr
  6. Allen JM, Mailing LJ, Cohrs J, et al. Exercise training-induced modification of the gut microbiota persists after microbiota colonization and attenuates the response to chemically-induced colitis in gnotobiotic mice. Gut Microbes. 2017; 1.
  7. Allen JM, Mailing LJ, Niemiro GM, et al. Exercise Alters Gut Microbiota Composition and Function in Lean and Obese Humans. Medicine & Science in Sports & Exercise. 2017; 1.

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