This! My wife had chronic knee pain that no one could figure out given her relatively youthful age. A smart trainer spotted that her leg muscles were very, very

This! My wife had chronic knee pain that no one could figure out given her relatively youthful age. A smart trainer spotted that her leg muscles were very, very weak. She strengthened them and now has no knee pain - and in fact is running about 20-25m per week where before she assumed she'd never run again.