Believe it or not, not every athlete wants to build massive muscles. Think about wrestlers, MMA fighters, gymnasts, or athletes who use their own body weight as their primary resistance, they need the strength, but the additional bulk can be more hindering than helpful.
What’s important to consider is that strength is not solely a property of muscle, but rather a property of the motor system. So going for the pump, total muscle exhaustion and complete muscle annihilation is not the name of the game here. Your body increases its strength by a) recruiting more muscle fibers in a particular muscle group and b) increasing the firing frequency of your motor neurons (neurons and muscle fibers).
Apply these methods below to jack up your strength, but not your size.
1. Lift Heavy
Lifting heavy (> 90% 1RM) will improve strength by recruiting what are called high-threshold motor units. The muscle fibers associated with these motor units have the most potential for increasing strength. However, they fatigue quickly. Maximal lifting is best applied to multijoint exercises (e.g., squats, deadlifts, presses, and pulls). Even though the weight is heavy, your intent should be to move the weight as fast as possible. This will ensure you’re recruiting as many fast-twitch muscle fibers as possible.
2. Lift Explosively
Made popular by Westside Barbell, speed lifts (e.g., box squats, speed deads & speed bench) are an excellent lifting style to teach acceleration and power development. Loads around 60% 1RM should be used and moved as fast as possible. Accommodating resistance (e.g., bands and chains) can be applied to further challenge your ability to accelerate the load. Obvious explosive exercises that should come to mind are the Olympic lifts (e.g., clean & jerk and the snatch) however, medicine ball throws and kettlebell swings also fit into this category as well.