Now, all of America knows the best-kept secrets of the first lady's fitness regimen, thanks to her cover spread in the upcoming issue of 'Women's Health' magazine.

Michelle Obama has appeared on numerous magazine covers but this one unveils her intense weight-training and cardio workout, complete with rope-jumping and kickboxing, lunges and bench presses.

Her fitness regimen is detailed by her personal trainer of the past dozen years, Cornell McClellan, who began working with the first lady in 1997 at his Chicago fitness studio.

"She's truly committed herself to the importance of health and fitness," McClellan tells Women's Health.

The magazine reveals step-by-step the nine-minute arm workout that inspired one Washington pundit to nickname the first lady's prodigious arms 'Thunder' and 'Lightning'.

The first lady has become something of a fashion icon for arm-baring outfits that reveal firm, toned biceps and triceps.

She also caused a stir while on vacation last month when she was photographed descending the steps of the presidential plane Air Force One in shorts that rose to mid-thigh.

Not to be outdone, President Barack Obama — for a second time — appears on the cover of the companion 'Men's Health' magazine, speaking about his own efforts to stay in shape despite a hectic work schedule and demanding family life.

He also famously has appeared in the US media baring his pecs while on a beach vacation in Hawaii.

As part of the same health and fitness push — and coinciding with ongoing White House efforts to promote its planned overhaul of US healthcare — more Obama interviews and profiles also are featured next month in another magazine from the same publisher 'Prevention' as well as their new publication 'Children's Health'.

In 'Women's Health', Michelle Obama discusses her emphasis on proper nutrition, especially when feeding her two daughters Sasha and Malia.

"They're not hoarding junk food because they don't get it at all," she tells the magazine.

As for her own well-being, "getting enough sleep, eating right and exercising reduce my stress levels," the first lady said.

"A really good workout is a great stress-buster."

AFP