FYI Fitness Tips: The math behind tired marathon legs

In this week's FYI Fitness Tip, expert trainer Phil Clark breaks down the science behind why running a marathon is so taxing on your legs.

More tip videos:
Why chains help in bench press exercises
Don't be intimidated by cable-pulley machines
A solution for your pull-up problem

Getting the most from bench press machines
Ab workouts that protect your back
Lunges minus the knee pain