Another study with similar results also showed that added weight had less effect at faster speeds. Implications of these findings are in the areas of orthotic devices, light weight trainers and racing flats. The principle of risk vs. gain is important when evaluating these areas. Running a couple of short races without the devices may not be much risk, but if you are racing frequently or running long distance events the risk of injury may be greater than the small gain in efficiency. Light weight trainers tend to wear out more rapidly and are not known for great support so your biomechanical and financial needs should be investigated before they are chosen.
Racing flats give little or no support and tend to lack cushioning.
Always the gains from less weight must be weighed against the increased risk of injury. The antagonist muscles must relax in coordination with the contraction so that they don't provide unwanted resistance to the movement. Other muscles in the body also must coordinate in both contraction and relaxation to stabilize the body and maintain other body actions. During endurance activities, in each muscle, groups of muscle fibers are used to perform work while others are rested and vice versa. These complex processes are governed by neuromuscular coordination.