High intensity anaerobic training can not be sustained in high volume continuously. It can only be sustained in high volume for 6-8 consecutive weeks maximum. After this time, the effects of the sustained efforts risk athlete burn-out and illness. Understand the risk associated with these sessions. High intensity sessions, like those suggested in the 4 minute, 1 minute and 30 second target sessions above, are best applied in the few months leading up to competition. They sharpen the athlete and develop race condition.