No tires required
TRX, a fitness program dedicated to using your own weight as resistance, is gaining speed among trainers.
One advantage is TRX's lack of equipment. Unlike CrossFit's abandoned warehouse locales and tire tossing and P90X's necessity of dumbbells and in-home pull-up bars, TRX's only requirement is a nylon strap.
TRX relies upon suspension training to work core muscles and allow devotees to easily use their own body weight to adjust the difficulty level of their workouts.
Designed by a former Navy SEAL, the process is similar to the one SEALS use to train for combat.