A new study has revealed that letting out a powerful sound during exercise may have a beneficial effect in spite of the fact that it may alarm all that surround you. It seems that letting out a grunting noise during explosive movements required while lifting weights, practicing martial arts and even tennis strokes can be traced to our historic ancestors and the noises they made as they heaved giant stones as projectiles. To test the theory researchers gathered 20 martial arts men and women to test their power on a kicking bag. The bag contained a device to measure force. When the kick was accompanied by a grunt or a yell the force of the kick was 10% greater which proved that it can be a useful competitive tool.