The brain of fatigued athletes works differently during functional balance tests used to determine sports injury risk

Researchers from the Human Physiology and Sports Physiotherapy research group at the Vrije Universiteit Brussel have shown that physical fatigue affects an athlete’s brain when performing a functional balance test. The accuracy with which a representative group of recreational athletes responded to a novel reactive balance test was measured, alongside their response time. They performed this balance test, which could be used to determine the risk of injury, both before and after heavy exercise. Their brain activity was also mapped.

The experiment, led by postdoctoral researcher Bruno Tassignon, showed that physical fatigue has a significant impact on the brain, and fatigue could be detected in this functional balance test with an additional cognitive component. This does not seem to be the case with traditional functional balance tests, where no negative influence of fatigue on performance could be found. This may be explained by the fact that the athlete knows exactly what will happen from start to finish and no unexpected cognitive stimuli are presented.

"In this new dynamic reactive balance test, we measure both the response time and accuracy in athletes following a fatiguing intervention," says Tassignon. "And that’s new. We are simultaneously measuring the functioning of the brain and we observe fatigue related changes there as well."

Important for both recreational and elite athletes

The findings could be important for both recreational and elite athletes. Previous research had shown that certain sports injuries occur more often toward the end of a sports session, such as during the second half of a soccer game.

"The literature also shows that the sport injury risk increases as cognitive performance declines," says Tassignon. "In our study, response time remained more or less the same, but the accuracy decreased significantly, while at the same time we saw changes in brain activity due to the induced fatigue. Thus, based on previous literature, there could potentially be a role for the brain and fatigue in the development of certain sports injuries."

In addition to a physiological explanation, there may be psychological aspects leading to reduced accuracy and increased response times among athletes when they are fatigued.

The study was published under the title Acute fatigue alters brain activity and impairs reactive balance test performance