Children who play vigorously for 20 to 40 minutes daily might be making their brains as well as their bodies stronger, shows a latest study that highlights why physical activities are essential for kids.

Researchers from the Medical College of Georgia in the US divided 163 overweight children aged seven to 11 into three groups and observed them for three months.

While the first group did no physical activity after school, the second group did 20 minutes of vigorous physical activity five days a week after school. The third group did 40 minutes of such activity on those same days, reported the online edition of USA Today.

The activity groups played intermittent, high-energy running games, such as flag tag, relays, jump rope and modified basketball. They wore heart-rate monitors and were rewarded for maintaining a high average heart rate.