A person's anaerobic threshold has been reached when their body is under extreme conditions and the burning of oxygen can not keep up with the body's demands.
Novak Djokovic captured his second straight Wimbledon title and the third of his career by defeating Roger Federer 7-6, 6-7, 6-4, 6-3 in Sunday's men's final at the All England Club. Djokovic is the first man to repeat as Wimbledon champion since Federer won five in a row between 2003 and 2007.
He is 29. If the oldsters end up winning, Federer would become the oldest man to win Wimbledon in the Open era, which began in 1968. Serena would become not only the oldest woman to win Wimbledon, but to win any Grand Slam tournament in the Open era.