Weighted vests are used to make exercises such as push ups, walking, jogging and playing sports more challenging. Vests can weigh as little 5 lbs. or as much as 80 lbs., depending on the model. Most weighted vests are adjusted by adding or removing metal ingots from Velcro secured pockets. This allows you to gradually increase the weight of your vest as you get fitter and stronger.
Uses
Weight vests are used by the military, law enforcement agencies, fire fighters, athletes and fitness enthusiasts. Weighted vests can be used to simulate wearing body armor or firefighting equipment to develop job-specific fitness or just to make playing sports more demanding. Some athletes use weighted vests to increase their strength for running and jumping. Although weight vests are an accepted tool for increasing your fitness and/or strength, they also present an increased potential for injury.
Mechanism of Injury -- Spinal Compression
Weighted vests sit on your shoulders and are fastened around your waist. This weight is supported by your spinal column, which consists of 33 vertebra and intervertebral discs. The added weight provided by the vest may lead to compression of your intervertebral discs, which is a reduction in the spaces between vertebrae. Compressing intervertebral discs can, says author and spine health expert Stuart McGill, lead to back pain and as well as injury.
Avoiding Spinal Compression
To reduce your risk of suffering a compression related injury avoid performing activities that are overly impactful. Jumping and running place a large amount of impact through your spine, even when you are not wearing a weighted vest. Running and jumping while wearing a weight vest may be a necessary risk of you are training for competitive sports or the military but if you are working out for general fitness and health, the risks of serious back injury outweigh any potential benefits.
Mechanism of Injury -- Altered Center of Gravity
Normally your centre of mass is directly over your base of support. That is to say that your weight is over or very close to your spine. This means that very little muscle tension is required to keep you upright. A weighted vest, especially a heavily loaded one, will move your centre of mass away from your base of support and subsequently place an additional load on your muscles. If this load is uneven --- there is more weight in the front of your vest than the back for example --- this can result in a lot of stress on the muscles on the opposite side of the load. If the weight is located on the front of your body, your back muscles will have to work overtime and the muscles of your abdomen will be required to work harder than normal if the load in on your back. Either scenario places your spine in a mechanically difficult position which could result in injury.
Minimizing your Risk
To get the most out of your weighted vest while minimizing your risk of injury, you should always ensure that the weight is distributed evenly between the front and the back. Failure to do so significantly increases your risk of injury. Also ensure the weight is distributed evenly from left to right to avoid any lateral stresses. If your weight vest has a waist belt, ensure it secured tightly to keep the weight as close to your body and therefore over your base of support as possible.
References
- "Ultimate Back Fitness and Performance"; Stuart McGill; 2004
- "Sports Injuries: Their Prevention and Treatment"; Lars Peterson and Per Renstrom; 2000
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