Ennis sacrifices Delhi in pursuit of London gold
After missing the 2008 Beijing Olympics with a career-threatening injury, the 23-year-old won heptathlon gold at the 2009 World Athletics Championships in Berlin.
In a busy season, Ennis will compete in March's World Indoor Championships in Doha and the European Championships outdoors in Barcelona in July, although she will not take part in October's Commonwealth Games in Delhi as it will hamper her winter training schedule ahead of the 2011 season and the defence of her world crown.
"I've got to move on and focus on this year. I feel like I've had a good winter season with training," said Ennis.