I stand by my statement. Free weights increase the risk of injury to the elbow, especially with speed training. The more weight a student uses the harder it is to stop a technique before full extension. With elastics there is resistance which helps to reduce the risk of hyperextension. Hyperextension injuiries in the legs can lead to a torn meniscus, dislocated knee cap, and torn ligaments and in te earms can lead to dislocation and torn ligaments. Ultimately a student can become injured doing something as simple as a side kick if they don't pivot properly. My point is that as instructors we want to do our best to make sure our students stay healthy by using training methods that reduce the risk of injury. You can enver eliminate the risk of injury due to the nature of the sport, but we do want to reduce it.