Theodore Carstens became interested in fencing listening to his grandfather tell tales of his sabre duels during his youth at a German university. After the 1904 Olympics Carstens turned professional and toured the Orpheum Circuit with Col. Carl Brosius, another Milwaukee swordsman. He occasionally tried other professions, such as working on the Baltimore grain exchange, but always returned to fencing, serving as a coach and running a fencing school, and writing about the sport frequently. He was fond of tracing modern fencing through history back to the days of the knights in armour fighting with broadswords. Carstens never married and lived in a spare apartment decorated by his own paintings of fencing scenes.