Strength is a very important asset in football irrespective of the level (amateur, professional etc.).
It can be divided into two major types namely upper body strength and lower body strength.
The upper body strength is needed to shield the ball, for throw-ins, to hold off opponents as well as for overall power and explosiveness.
For lower body strength, it is required for tackling, kicking, twisting, jumping and also highly useful for explosive speed.
Strength can be further divided into three broader categories: Absolute or Maximal Strength, Strength Endurance and Muscular Power.
Absolute or Maximal Strength
Absolute strength is the optimum force that a muscle group can produce in a singular, momentary contraction. It is highly useful as the foundation of muscular power and speed. It is also beneficial for shielding the ball and holding off opponents.
Muscular or strength endurance is the ability of a muscle group to produce high-intensity cum repeated movements. It is important for soccer and probably more essential than all-out strength.
Power is the product of both speed of movement and absolute strength. An increase in either without decreasing the other brings about an increase in explosive power.