A series of very important physiological events occur during the first few minutes that a horse exercises. The spleen contracts, releasing more oxygen-carrying blood into the bloodstream. The heart begins to work harder, which increases bloodflow and oxygen to working muscles. As the muscles contract, they produce heat, which is commonly referred to as “warming up”.
Warming horses up properly prevents injury. It is very important not to overstretch a cold muscle. Properly warmed-up muscles are supple and resilient, rebounding from stretch without injury. Cold muscles and their associated tendons can tear – and the results of this damage can, in many cases, be permanent.
The best way to warm up is to pick up an easy jog for 10 to 15 minutes. Allow the horse some rein at first so that his neck is not too tense. About ten minutes into the warm-up begin some gentle suppling exercises, such as backing, circling, and lateral movements. As your horse starts to loosen up, slowly work into your normal workout.
When the weather is very cold, increase your warm-up time by 5 to 10 minutes – it takes longer for muscles to adapt to cold temperatures. Very stiff or “cold-backed” horses may benefit from blanketing for several hours before performance, in order to keep large muscles warm. I believe that magnetized blankets are even more beneficial for this. Some even benefit from the application of a wool blanket over the loin area while exercising in cold weather.
Avoid new exercises that involve a lot of stretching until you are at least 30 to 45 minutes into the horse’s workout. By this time the horse should be well warmed up, but not physically and mentally tired. You should strike a balance between a properly warmed-up horse and one that is not so tired that he is prone to injury from breakdown due to exhaustion.