I was jumping rope at a boxing club a few days ago and now my left shin hurts. why is this?

Overuse tibia injury: Shin splints is an overuse stress injury to the tibial leg bone. Often times, a sudden rapid increase in either mileage or running intensity can trigger an episode of shin splints. Most are self-limiting and will go away with simple rest or decreased mileage and intensity. Ice and anti-inflammatory medications may help as well.