Absolutely. We call this the offline mode. You can start a new session from the fitness tracker directly by scrolling down to "Exercises" and hitting "Gym".
At the end of the session, please long press the "Select Key" and proceed to select the muscle groups you worked out on and allow the band to be synced with your phone post workout. This way you don't have to carry the phone while you workout. We will be adding a video here to show you how to do it.