After a fall I took when I was riding alone in the arena, it occurred to me that it would be a good idea to wear a crash vest, also called a body protector, while I ride.
When my daughter needed a crash vest to compete in cross country jumping when she was in Pony Club, we didn't know much about choosing a vest. Since that time, designs have improved and it is much easier to find crash vests with safety standards approved with organizations like ASTM, EN and BETA. The first vest we bought looked a bit like a large blue life jacket. As awkward as it looked and felt, she was glad to have it on one day when her pony refused approaching a large log and she was spun off, landing on her back across the log. She walked away feeling a bit foolish, with only her pride injured.
No amount of 'safety equipment' will keep you completely safe, but a crash vest is one way to protect your inner organs, ribs and spine. The padding helps prevent or lessen an injury from the impact of a fall, and reduce the amount of damage should you hit an obstacle or be hit by a hoof on your way down.
Do You Need a Crash Vest?
Crash vests are required by some sports such as cross country jumping. Many jumping also wear them. They are commonly seen on rodeo riders and jockeys. But more pleasure riders are wearing them as extra protection. If you have confidence problems while riding, a crash vest may help make you feel more secure.
Are Crash Vests Comfortable?
Since her second safety vest isn't being used, I thought it was wiser to wear it than leave it hanging on its hook. At first, it felt cumbersome. But while I rode, it didn't impede my upper body or arms in any way. If anything, it made me more aware of my posture, which is something I constantly struggle with. As long as I keep moving in hot weather, the air flow underneath the vest keeps me surprisingly cool. A quick dry shirt is helpful once you stop, because I found I warmed up more after I got off then when I was riding. For cold weather riding, the vest is an extra layer-something I always welcome.
Design
There are several designs of body protectors available. Like my daughter's first vest, some look like buoyant vests worn for water safety. The vest I have now, an older Tipperary model, is more form fitted with lacing at the sides. This particular vest is not rated by ASTM and I'd recommend if you are buying a new or used vest to look for ASTM, EN or BETA standards, (ASTM also approves riding helmets in ). Some will have hook and loop fastener at the shoulders for adjusting the length and most have a zipper closure at the front, although some have clasps similar to a life jacket. The back of the vest extends down to protect your lower spine. Some have attached or detachable arm and shoulder pads. Some vests are designed to fit women. High visibility vests for riding along roadsides or during hunting season do not provide the same protection as approved crash vests. These of course, can be worn over your body protector.
One of the newest vests features a low profile style, with an air canister that inflates the vest if the rider has an unscheduled dismount. A pull cord attached to the saddle activates the air, which fills the vest almost instantaneously. From what I could see of online prices, these vests cost over twice as much as a regular vest. 
Sizing
>Crash vests come in a variety of sizes available from small children through to adults. Because various vests seem to fit a little differently, it's best to try a several on to find the best fit. You don't want it to rub beneath the arms, or ride up because the back is too long and hits your saddle. If you plan to wear your vest under your show jacket, be prepared to buy a slightly larger size jacket. Wear the type of shirt you'd normally wear to ride when you shop for your vest. You'll probably be more comfortable in a shirt with sleeves, rather than a tank or racer back top. The vest should cover the sternum at the front and the large bone at the nape of your neck at the back.My daughter had a lot of fun color coordinating her vest with her other cross country gear. Some manufacturers offer customized vests. Be prepared to spend about $200 for a new vest. Like helmets, vests should be replaced after a time. BETA recommends every three to five years.
