Competition may lead to release of 
Chemical energy dopamine insulin heat energy emissions growth hormone adrenaline Energy
A B C D E F G H
Aggression is the drive, the adrenaline, the power.
Competition may lead to release of adrenaline
Competition may lead to release of  (A) Chemical energy (B) dopamine (C) insulin (D) heat energy (E) emissions (F) growth hormone (G) adrenaline (H) Energy