Sports and physical exercise require the co-operation of multiple muscles. The brain cannot direct all of these simultaneously. Instead, a skilled athlete completes their movements habitually, as if by instinct.

Muscles can be taught to co-operate with one another through practice. This is why athletes practice their sport every day. Practice makes perfect. 

Depending on the sport, athletes must develop their speed, their strength or their endurance. All of these things can be improved through practice. 

You can increase your movement by "teaching" your muscles to contract at faster rates. Likewise, you can increase your strength and endurance by practicing.

Sports are not the only form of physical exercise. You can also improve your speed, strength and endurance by walking, swimming and bicycling.