Be careful when training with elastic exercise bands. Here’s a case report from http://www.hindawi.com/journals/criopm/2013/189837/ regarding an injury sustained during a CrossFit training session:
This patient had a traumatic giant retinal dialysis and retinal detachment as a consequence of elastic resistance band breakage during CrossFit training. To our knowledge, this type of injury has not been reported. Elastic bands are being used increasingly as an exercise accessory to provide resistance, not only in CrossFit, but also in other popular exercise programs, such as P90X. Some elastic bands consist of latex strips of variable lengths and resistance while others are elastic tubes with soft grip handles on the ends (Figure 1). With repeated use, elastic bands can weaken and eventually break. When it is under tension, a broken elastic band can snap into the eye causing injuries such as hyphema, cataract, or retinal detachment. Dialyses and giant retinal tears are responsible for 69 percent of traumatic retinal detachments.
Elastic bungee cords have been reported to cause a variety of ocular injuries. Elastic resistance bands might appear to be safer since they do not have metallic hooks on their ends as bungee cords do, although some have soft handles. Nevertheless, an elastic band, under high tension, can snap causing a high velocity missile impact with the eye, causing similar injuries to a bungee cord. Exercise participants and trainers should be aware of the potential for this type of injury. Precautions include the use of protective eyewear and regular replacement of worn elastic bands. Examining bands before and after use, looking for nicks, punctures, or tears, and discarding worn bands may prevent these injuries.