Each boxer has an energy meter that depletes as they are hit during a bout. The player's boxer will be knocked down when the energy meter reaches zero. The boxer's level of physical activity has no bearing on the meter (apart from getting punched).
There's also a meter for the boxer's head and body, which indicates how much damage each of these sections has taken. When the head or body meters are both 0, that boxer will receive a lot more harm if he or she is hit in that location
Punches deplete a fighter's energy bar by a consistent amount, regardless of how much damage they cause (unlike in many other boxing games, where punches vary depending on how likely they are to knock a boxer out).
Use arrow key and try some key ( Shift, Enter, Z, X, A, S , Q, E, R, T, G, F, H ) to controls the game.