Mark McClusky says for elite athletes today, pushing boundaries and breaking records is all about "the aggregation of marginal gains."
Mexico’s President-elect, Enrique Peña Nieto, will take office on Saturday and vows to change his country’s drug war strategy.
Outgoing President Felipe Calderón declared war on the cartels six years ago, and the fight has been devastating, claiming more than 40,000 lives.
Peña Nieto says he will downsize the federal police, which grew seven-fold under Calderon, but has been dogged by corruption allegations.
The BBC’s Will Grant reports.