well when you pull a tendon in your foot you lose your arch support and it hurts to walk since you have no spring action. Hypothetically you could wrap it up with an ace bandage and limp around in the gym and train upper body/abs. I would personally take another week off, keep a clean diet and recover, then ease back into it. I shadowed a pediatrist this past winter and the patients that came in with chronic foot pain had not let their arches heal correctly and simple overstretched the tendons to a point of no return without surgery.