Dr. Doug McGuff, the author of Body by Science (a book I highly recommend), suggests doing resistance training only once every seven to ten days. His research shows that this offers greater benefits than more frequent exercise,

anaerobic modes of metabolism are experienced in bursts, achieved through physical activity that is performed at a much higher intensity (and therefore impossible to sustain). This may include sprinting at near-maximal effort for ten to twenty (or even thirty) seconds, taking a break, and repeating the process. Resistance training—weight lifting, f