Physically trained participants showed improved performance on tests of cognitive function, heart rate variability and physical fitness (as measured by maximal oxygen consumption, or VO2max) when compared with detrained participants, shows a study published in the European Journal of Applied Physiology (2004; Aug. 25, electronic publication).
Researchers subjected 37 male sailors from the Norwegian Navy to an 8-week physical training program and then performed initial cognitive testing. All subjects showed similar results in the pretest physical and cognitive function tests. Subjects were then split into two groups: one that continued fitness training and another that stopped. After 4 more weeks, all subjects participated again in physical fitness and cognitive function tests. The detrained group had lower aerobic fitness, lower heart rate variability and lower scores on tests of executive function.
According to the authors, these results suggest that there is a relationship between physical fitness and cognitive function and that this relationship is associated with heart rate variability. Rapid heart rate variability, efficiently mediated by the nervous system, is an indicator of heart health. More research that combines neuroimaging with physiological measures to clarify the exact nature of this relationship is recommended.