Octane Fitness xR4 recumbent elliptical cross trainer Octane Fitness xR4 seated series comprising xR4c and xR4ci rear drive seated elliptical cross trainer, has much to boast about. Their cutting edge Powerstroke technology, an ergonomically design offering a comfortable workout experience, innovative and sophisticated electronics and highly challenging, efficient workouts contribute to their great appeal as a fitness machine with workout routine that burns 23% more calories than say, a recumbent bike.