The NFL and the players' union said the number of players randomly tested each week during the pre-season, regular season and post-season would increase from seven to 10 per team bringing the total number of tests conducted annually to 12,000.

The NFL will begin testing for erythropoietin (EPO), a blood doping agent used to artificially increase the production of oxygen-rich blood cells.

The NFL said it would also introduce the additional use of carbon isotope ratio testing on a random basis to detect low doses of testosterone. Previously, carbon isotope testing was only used to confirm positive tests for testosterone.

There were no announced increases in the penalties for players caught using performance-enhancing substances which remain set at a four game ban for first time offenders and a one year suspension for a second positive test.