As a busy medical student, hours and hours of studying never seems to be enough. I find myself frequently torn between cherishing those extra thirty minutes of study time, or getting out the house and going for a run or another form of physical activity. However, when I choose to exercise, I never regret it and typically end up ready for another few hours of solid study time, feeling extra rejuvenated and focused. With time being such a crucial element in my life, as well as millions of others lives, I wonder, does it really matter what time we exercise? Is there a particular time to exercise that yields better memory recall?
It seems that I’m not the only one that has these questions, as a study discussed on Reuters.com evaluated this topic recently. The aim of the study was to determine if post-learning physical exercise affected memory retention and whether its effects were time dependent. The study had 72 participants, which all performed a learning task that consisted of learning 90 ‘picture-location’ associations over 40 minutes’ time. The participants were divided into three groups, and after the learning task, completed one of the following:
35 minutes’ interval training of up to 85% maximal heart rate immediately after learning
35 minutes’ interval training of up to 85% maximal heart rate 4 hours after learning
No exercise at all
The results showed that participants in the delayed exercise group, exercising 4 hours after the learning task demonstrated significantly higher recall than those who exercised immediately after and those who didn’t exercise at all. The study showed that in the individuals in the group with delayed exercise, activity in the hippocampus was stronger, demonstrating increased learning. Personally, when I exercise, afterwards I feel energized, happy and clear-minded, like a fog has been lifted off of my brain. The results illustrated similar effects, as it was shown that during exercise more of the “feel good” hormones, dopamine and norepinephrine are released.
While the results of the study are promising, some questions still remain about the methods and the validity. Did the participants already maintain a regular exercise program? If so, that would likely skew the results, particularly how much memory recall they experienced as a result of the exercise. Were the participants of normal body habitus, or overweight or obese? If they were not a ‘normal’ weight, then likely the results could also have been skewed.
In the study, participants did interval training on a stationary bike. However, other studies have shown that other types of predominantly, non-cardiovascular types of exercise, such has resistance training also provided benefit with memory recall. As our technology improves, it would be interesting to see if over the years we can personalize which type of exercise elicits the most memory recall. Further realms of research would be apt to look into non-cardiovascular exercise and activity in the hippocampus. I know that with my busy schedule I can’t always get in the amount of exercise that I would like, but at least now I know when I should try to exercise.
Keywords: exercise, memory recall, time, learning,