These are rejects from Apple's last silhouette ad campaign.

Yoga is a discipline that takes practice and guidance, preferably with a knowing instructor. Or you could choose to strengthen your limbs and release your kundalini yourself, with help from the App Store.

Yoga STRETCH presents a list of poses, many of them simple to get in and out of, plus physical and mental benefits of each pose. For example, the "cobra" says it improves posture and energizes the mind. Yogis can set the time they want to spend disciplining their minds and limbs, pause, and even skip an undesirable pose. The instructor is knowledgable, and the poses, shown in silhouette, are easy to decypher. This app, however, does not completely liberate you from suffering.

Although these poses are considered basic by practitioners' standards, several are difficult, if not impossible, to achieve by the untutored and unlimber. Take the "extended-leg stretch." Please. In fact, if done improperly, we see serious potential for both comedy and tragedy. We wanted the poses ranked by difficulty level, so beginners can say "om" and not "ow."

The sound of one tendon ripping.

The app itself has some bugs: we could not hear the instructor's voice unless we were wearing earphones. Try to pose while holding your iPhone in one hand while swatting away earphone cords. Unless you can stick your iPhone in a pocket or tuck it into your bra, the result is an unlovely, flailing tangle.

And the sound is weak. Yoga STRETCH gives an option for background sound, such as "transcendental whirlwind." Each sound abruptly repeats in a 50-second loop, breaking relaxation. Plus, the instructor audio sounds as if she recorded in her bedroom.