Study: High-intensity interval exercise seems to briefly impair mechanisms of reward learning

A new study has found preliminary evidence that high-intensity interval exercise temporarily impairs reward learning mechanisms in the brain. The research, which was published in Physiology & Behavior, indicates that this type of exercise does not improve all aspects of cognitive function.

“Performing a single session of continuous aerobic exercise (i.e., cardio) transiently improves some measures of cognition including attention, inhibition, and processing speed. This post-exercise period seems to be an ideal time perform a cognitively demanding task (i.e., learning something new) given the boost in cognition,” said study author Jeremy J. Walsh of Queen’s University.

“The aim of this study was to investigate how very brief, high-intensity interval exercise (HIIE) impacts mechanisms of reward learning using electroencephalography (EEG) in university aged students.”

In the study, 25 healthy university students participated in two experimental sessions. During one session, they performed interval training consisting of burpees, jumping jacks, mountain climbers, and squat-jumps for about 10 minutes. During another session, which was used as the control condition, they quietly watched a nature documentary for about 10 minutes instead of exercising.

After each session, the students had a 10 minute rest period and then completed a computerized reward learning task while the researchers monitored their electrical brain activity.

The researchers found that a pattern of electrical activity typically seen in response to receiving a reward — known as reward positivity — was reduced after HIIE.

“The take away from this study is that performing HIIE seems to impair mechanisms of reward learning,” Walsh told PsyPost.

“This finding can be viewed from a few different perspectives: the brain processes that underlie the earliest stages of learning may be ‘turned down’ by HIIE, which may have a negative impact on an individual’s ability to learn a new task.”

“However, these findings may also be important for individuals with addiction (smoking, gambling, etc.), as their reward-learning pathways seem to be hypersensitive to certain stimuli. Going forward, it would be interesting to see if HIIE can help to reprogram the reward pathways of these individuals,” Walsh said.

All research includes some caveats, and the current study is no exception.

“It is important to recognize that we only assessed changes in reward learning 10-minutes after HIIE; therefore, we do not know how long this impairment lasts for. An important next step will be to better characterize how reward learning is impacted over the course of a couple of hours following HIIE,” Walsh explained.

“Another important point is that we did not assess the physical fitness of the participants in this study. Previous research has shown that individuals with higher physical fitness improve cognition after HIIE, whereas their less-physically fit peers did not.”

“Accordingly, it is possible that our findings in part reflect the level of physical fitness of our participants. If participants were given a longer recovery period after HIIE (>10 minutes), we may have observed a different response,” Walsh noted.

The study, “High-intensity interval exercise impairs neuroelectric indices of reinforcement-learning“, was authored by Jeremy J. Walsh, Francisco L. Colino, Olave E. Krigolson, Stephen Luehr, Brendon J. Gurd, and Michael E. Tschakovsky.