Speed vs agility — what's the difference?

Parents, coaches and athletes use 'speed' as a catch-all. In sports science it is more useful to split the idea up.

• Speed: how fast the athlete can move, especially in a straight line.
• Acceleration: how quickly they reach that speed.
• Agility: how efficiently they decelerate, change direction and re-accelerate.
• Quickness: how fast they react and start the movement.
• Game speed: whether any of that shows up in competition.

A hockey player can have respectable straight-line speed and still look slow on the pitch if they cannot stop and turn. A rugby winger might need a different ratio. A netball player lives in agility and landing. This is why we test rather than put every athlete on the same ladder drills.