The poster was part of the foundation's 30 A Day campaign to encourage people to take 30 minutes of exercise every day.
The Northern Ireland Chest, Heart and Stroke Association said it had been bombarded with complaints from people who believe it is responsible for the campaign.
Andrew Dougal, chief executive of the charity, said: "People have threatened not to give us any more money. We've never used shock tactics or sexual imagery in our campaigns."
The Advertising Standards Authority rejected a complaint that the advert was offensive.
Betty McBride, director of policy and communications at the foundation, said: "We are proud of our contribution to saving lives in Northern Ireland."