A footballer's knee feels the full force of the game's explosive demands - every impact, every twist, every turn, every collision.
Exposed to the elements, it's vulnerable and needs protecting. As much fun as it would be to slip on an armour plated knee pad, that's not an option so there's only one thing for it - build an indestructible joint.
More after the break
Making sure your quads, glutes, hips and hamstrings are robust and flexible spreads the workload and eases the pressure on the knee.
In this video Erith takes City defender Micah Richards through an exercise that challenges the knee joint and works the rest of his lower body.
Micah is an ambassador for If U Care Share, a charity that encourages young people to discuss their problems: www.ifucareshare.co.uk
Build explosive power
Boost your hamstring strength
Add an extra spring to your leap
Build bigger and stronger pins
Build a rock-solid core
Switch on your glutes for 90 minutes: Part one
Switch on your glutes for 90 minutes: Part two
Fire up your hips for action: Part one
Fire up your hips for action: Part two