Joseph Pilates "invented" his method of body conditioning during the First
World War and then took it to America where he worked with dancers. It is a
method of body conditioning which strengthens and tones muscles, and
improves posture, flexibility and balance. The exercises strengthen your
"core" muscles - those around your mid-section - predominantly your
Transversus Abdominus, deep muscles which form a girdle around your body -
hence Pilates being good for some back problems.
A class usually follows a pattern - finding correct posture, a few
mobilising moves, a whole host of Pilates exercises, followed by a general
stretch and a few minutes' relaxation. Sometimes people ache, sometimes
they don't - and just because you don't doesn't mean you're not doing the
exercises properly or are not working hard. You will work on the
deep muscles, possibly ones you didn't even realise you had!
You will work with your breathing whereby slow, controlled, flowing
movements are stressed.