Power yoga is a general term used to describe a vigorous, fitness-based approach to vinyasa-style yoga. Though many consider power yoga to be superficial "gym yoga," this style of yoga practice was originally closely modeled on the Ashtanga method.
Power yoga incorporates the athleticism of Ashtanga, including lots of vinyasas (series of poses done in sequence) but gives each teacher the flexibility to teach any poses in any order, making every class different. With its emphasis on strength and flexibility, power yoga brought yoga into the gyms of America as people began to see yoga as a way to work out.
The Hatha Yoga Pradipika is a classical manual on Hatha Yoga. It was written in Sanskrit by Swami Swatmarama, a disciple of Swami Goraknath, in the 15th century. It is considered to be the oldest surviving text on Hatha Yoga. The Hatha Yoga Pradipika contains instructions on the practice of postures(Asanas), breathing exercises (Pranayama) and purification techniques(Kriyas), as well as a description of the different energies in the body.
Ashtanga yoga literally means "eight-limbed yoga," as outlined by the sage Patanjali in the Yoga Sutras. According to Patanjali, the path of internal purification for revealing the Universal Self consists of the following eight spiritual practices:
Yama [moral codes]
Niyama [self-purification and study]
Pranayama [breath control]
Pratyahara [sense control]
Samadhi [absorption into the Universal]
The word “vinyasa” can be translated as “arranging something in a special way,” like yoga poses for example. In vinyasa yoga classes, students coordinate movement with breath to flow from one pose to the next. Ashtanga, Baptiste Yoga, Jivamukti, Power Yoga, and Prana Flow could all be considered vinyasa yoga. Vinyasa is also the term used to describe a specific sequence of poses (Chaturanga to Upward-Facing Dog to Downward-Facing Dog) commonly used throughout a vinyasa class