Mechanical advantages of levers
Levers are used to multiply force, In other words, using a lever gives you greater force or power than the effort you put in.
In a lever, if the distance from the effort to the fulcrum is longer than the distance from the load to the fulcrum, this gives a greater mechanical advantage.
Second class levers have the best mechanical advantage, so they can move a large load with a relatively small effort.
At take-off, the high jumper applies large forces to the ground through their ankle. The ankle operates with mechanical advantage in order to resist these forces and enable the jumper to achieve flight