Hip strength , flexibility is very important. Sedentary people are at far greater risk of hip injuries in old age. It is established that elderly who get hospitalised for hip injuries or fall often recovery very slowly and may end up in the bed for longer -- very depressing. And the elderly fall and break their hips not because of weak legs but because the hip bones (which hold the entire body up and downwards too, if you think of legs) become porous and collapse on themselves... when this happens the legs collapse, causing a fall... for bones to become dense you need to work the muscles closest to it...When the hip bones become dense you are really strong. Louise Haye btw says hip problems indicate an unwillingness to progress ahead in a major decision in life!