While in law school at Notre Dame, Mary Wittenberg found balance by training with the Fighting Irish men’s cross-country team. When she joined the firm of Hunton & Williams in Richmond, Va., she continued to train at a high level. In 1987, she won the Marine Corps Marathon in 2 hours 44 minutes 36 seconds, qualifying for the 1988 Olympic trials.

At Mile 2, Wittenberg dropped out of the trials because of a surgically repaired knee and an injured back, but she has made her mark elsewhere in the running world since 2005, when she became race director of the New York City Marathon and president and chief executive of New York Road Runners.

The marathon would grow to become the largest in the world, with 50,000 participants, and Wittenberg, 52, would become one of the most powerful female executives in international sport.

On Tuesday, she announced her departure from Road Runners to become the global chief executive of Virgin Sport, an endeavor by the billionaire entrepreneur Richard Branson that will organize running and cycling races in Britain and look to expand to South Africa and the United States.