Britney Spears' personal trainer reveals her beach workout routine

Tony Martinez, the personal trainer to Britney Spears, has revealed that to get her into great shape he took her to the beach for workouts.

Speaking to E! News, Martinez explained that doing fitness routines on sand gives them an extra boost as it makes movement tougher, but the relaxing atmosphere of being at a beach is encouraging at the same time:

"I wanted her to have something at the beach. It's so calming and peaceful. You can see the dolphins out there, and I try to make the exercises facing the ocean."

He works out with Spears twice per week for sessions of around 40 minutes and added that he mixes up the types of training they do so that she doesn't lose interest: "I don't want it to get boring, so I change it up a lot. But it's always at the beach and it's always interval training."

Spears, meanwhile, is gearing up to unveil her lingerie collection and will launch it on September 9 in the USA and Canada, and then on September 26 throughout Europe.

Watch her music video for 'Perfume' below: