A cricketer catches ball 
A seasoned cricketer catches a cricket ball coming in with great speed,he draws his hand backward in act of catching the ball.

How can I explain this phenomena in terms of impulse?
In my text book it is explained in terms of momentum. If I recall correctly , it can be explained in terms of impulse too. But I am unable to put in exact words for this explanation (in terms of impulse).
 A: Impulse is the term used to describe a large force acting over a very small interval of time. It characterises change of momentum due to that force. If a force $F$ acts over a small time interval $t$, then the impulse of that force is $Ft$. Higher the impulse, larger the damage caused. A fielder draws his hand backwards to increase the time for the momentum to change, in other words to reduce the impulse. This is the same reason why cushions are used in high jumps. All these methods reduce the impulse. 
A: Imapct of object on any thing can be increased by two ways:
1) Short force in long time
2) Large force in short time
This large force in short time is impulse. 
Impulse is defined as:
Integral(F.dt)=change in momentum=impulse
If the fielder catches the ball the ball exerts a force on the hands of fielder. Since ball carries high momentum stopping it at once will cause a large force to act for a short time that is there is a large impulse acting on hands of fielder. But if the fielder moves his hands backwards he increases time for momentum to reduce. If time is increased impulse decreases therefore there is less imapct and fielder's hands are safe too.
