The upper part of the body is slightly inclined forward; the head
slightly thrown backward, to counteract the gravity forward: the breast
is freely projected; the shoulders are steady, to give a fixed point
to the auxiliary muscles of respiration: the upper parts of the arms
are kept near the sides; the elbows are bent, and each forms an acute
angle; the hands are shut, with the nails turned inwards; and the whole
arms move but slightly, in order that the muscles of respiration on
the chest may be as little as possible disturbed, and follow only the
impulse communicated by other parts--(Plate IX. fig. 1). There exists,
in fact, during the whole time of running, a strong and permanent
contraction of the muscles of the shoulder and arm, which, though very
violent, is less serviceable to the extended movements, than to keep
the chest immoveable, toward which the arms are brought close, the
flexors and adductors of which are especially contracted.