There are really 2 determinants of displacement, take off velocity and the angle of force application. We have already discussed angles of GRF (see Sparta Point 6/15/11), so we’ll focus on take-off velocity.For take-off velocity, it’s all about energy efficiency, particularly optimizing the stretch shortening cycle, which allows movements to be more explosive due to the storage of elastic energy in tendons (see Sparta Point 1/28/09). This energy storage is added onto a baseline energy production from the contraction of muscles. Such elasticity can be enhanced through training of athletic, explosive movements, such as jumping, sprinting, and even weightlifting (see Sparta Point 6/29/11). Of course, the proportion of fast twitch muscles, versus slower twitch, will also increase your body’s ability to store this elastic energy. But if you’re parents were slow twitch runners, be careful to optimize your extracurricular activities to optimize those muscle fiber changes (see Sparta Point 12/29/11). In addition to elastic energy, spinal stability is crucial to transmit the forces through your body into the ground (see Sparta Point 9/7/11). This transmission, previously likened to a faster internet connection of a computer, is improved when the trunk musculature is able to prevent any energy leakage. So if you need to optimize elastic energy and spinal stability, how do you choose which to focus on? At Sparta, we use a force plate to evaluate impulse, or takeoff velocity, giving objective insight into your elastic energy utilization. This force plate also allows us to glimpse spinal stability in a very dynamic matter, such as vertical jumping. Athletes with poor stability will create great force initially (LOAD), lose this energy, but gain it back as they finish the movement (DRIVE). These objective markers allow us to choose whether to focus on this spinal stability or elastic energy. In a more simple setting, you can compare your vertical jump’s relative performance, versus your strength performance on a squat. If your strength is superior, you’ll need to focus on more elastic energy utilization through plyometrics. If your vertical jump has higher values, that spinal stability is best improved through resistance training. So whether you are the predator or the prey, displacement will determine the outcome. But if you’re not working on the deciding factors of velocity or the GRF angle, your choice is a forfeit.
January 5, 2012
Displacement Allows us to Survive