The two main exercises for quadriceps include leg extensions (usually done on an exercise machine) and squats.

CNN: Will jogging hurt an obese person's joints?

For these moments, her nearly prehensile-looking feet, which have become as much her signature as her extravagant leg extensions, were not quite bare.

WSJ: Sylvie Guillem | Leaving Ballet Behind | Dance Review by

Less successful are some of the other ballerinas, who cannot quite reproduce the crispness of the Balanchine style - with its long leg extensions and slow turns - despite the presence of Mr Balanchine's anointed successor, Patricia Neary, in supervising the production.

BBC: Sparkling Stravinsky