Summary

Allan Melvill Pope Horse Training by Modern Methods

Usually the action of the leg is strong enough if it is placed against or a little in rear of the girth. If the action there is not sufficient, it may be carried back a little—never, however, to reach an angle of 45 degrees. The perfection to aim at is to have the leg move almost imperceptibly and vary its effects only by different shades of pressure; but with a horse that does not respond sufficiently to the demands, it becomes necessary to carry the leg back a little by bending the knee and keeping the heels low.
Source: Gutenberg

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