At what age is the highest risk of injury in sports?

Depends. Age isn't so much the issue as is striking a balance between strength/conditioning versus physical demands.
Male or female? It varies with male or female, but generally it's ranges depending on the type of sport as well. For instance, for men, achilles tendon ruptures are more common for those over 30 and under 55 who are considered "weekend warriors", but females are not considered the same risk. In which sport are you referring to and what gender?