Perry`s new video left her "sore and exhausted"

Los Angeles: Pop star Katy Perry says she had to train so hard to get into shape for her latest music video `Part of Me`, that it left her sore and exhausted.

The 27-year-old singer admitted that she hired a personal trainer to tone up for the video, which sees her join the US marines after coming out of an adulterous relationship,reported MTV News online.

"I got on a meal plan. I`m still on that meal plan, although I cheat a little bit - I have to live!

"I got a fantastic person to work me out and get me into really good shape. On the actual base, I did a lot of things. I flipped girls, I learned how to fireman-carry. I know how to carry my weight a little bit more," said Perry.

However, the `Firework` hitmaker confessed that there was one stunt she was unable to master and the director had to edit that particular shot in the video.

"One thing I can`t do, and I hope that there are other people out there that feel the same way, is climb a rope. Oh my gosh, it`s so hard to climb rope! It`s all about grip and arms. I tried five or six times on set, but I had to cheat that shot. My hands were shaking," she said.

Though the production of `Part of Me` was a lot of hard work, Perry said she learned a lot from the Marines she worked with.

"This music video, as much as I was sore and exhausted, I was so educated on people in the service who I`ve always respected, but this time the respect goes beyond and above anything I could`ve imagined," she said.