Los Angeles Times

Breathe deep and build endurance with a little help

One thing that many free divers (divers who don't use air tanks), opera singers and Lance Armstrong have in common is strong respiratory muscles, which give their lungs ample oxygen-gathering capacity. Strong lungs can make any physical endeavor, from walking up a hill to running a marathon, a little bit easier. And there's a simple, effective tool to help develop your lungs: a lung trainer. When used a few minutes a day, these compact resistance devices - versions of which are commonly used for medical purposes - can strengthen breathing muscles and build endurance. They also can be used as a warmup before a workout. ...

Resistance is not futile
PowerLung: The fanciest of the respiratory trainers. It restricts air flow with an adjustable, spring-loaded valve.

Likes: The one-piece unit is said to strengthen inhalation and exhalation muscles; building the latter is helpful for swimmers and wind-instrument musicians. Resistance is easily adjusted by rotating a marked dial. Included an instructional CD.