Exercising four hours after learning a new material helps retain the information better than those who perform exercise immediately after learning or those who do not exercise at all, according to a new study. 
A team of researchers at the Donders Institute of the Radboud University Medical Center in the Netherlands enrolled 73 healthy volunteers, and assigned them with a task of learning 90 image-location associations over a period of around 40 minutes. Then, the researchers divided the volunteers into three groups. 
The first group was asked to perform a session of physical exercise immediately after learning, while the second was asked to wait for four hours to perform a session of physical exercise. The third group didn’t perform any physical exercise at all. 
A couple of days later, the participants were assigned with a test to determine how much they could retain from learning. Imaging their brains with the help of magnetic resonance imaging (MRI), the researcher found that the participants who were asked to exercise four hours after learning retained the information better 48 hours later than participants in the two other groups.

Source: QNA