Some argue that power yoga is not really yoga. But sweat and stretch your way through just one class with Baron Baptiste and you’ll be a believer in his high-intensity, high-temperature workout. Just ask the dozens of devotees who pile into his tiny Porter Square studio for his first-come, first-serve classes—or any of the professional athletes and celebrities (including Elisabeth Shue and Helen Hunt) who are fans. Lest you assume that Baptiste’s method forgoes the meditative properties of traditional yoga, be assured that classes are conducted in a soothingly quiet room where traditional breathing techniques and perfect form are stressed, though the room is heated to more than 90 degrees to keep the muscles loose. And at only $10 per session (a dollar extra for mat rentals), it’s an indulgence that can easily be made a habit.