[DJ Hicks is a recent graduate of Houston Baptist University and an Athletic Development Intern at Athletic Lab]
One of the most common questions posed by recreational viewers of track and field regarding sprinters is, “If they only run with their legs, then why are their arms so muscular?” A fair question to ask, this is often one of the biggest conundrums for novice viewers of the sport when the Olympics come around. Specifically looking at the 100m dash, it is not uncommon in the Olympic final to notice what appears to be sprinters whose arms are seemingly the same circumference as their thighs. Obviously, these are world class athletes who to some extent, know what they’re doing to be competing on the highest level of athletics. There must be a reason, but what is it? In a study conducted by Richard Hinrichs, of Arizona State University, this question was addressed.
Using 10 distance runners moving at various speeds on a treadmill, Hinrichs was able to determine arm and leg involvement with the help of electromyography (Hinrichs). In doing this, Hinrichs found that the biggest contribution of the arms came from their ability to meet, and combat, the vertical angular momentum of the legs (Hinrichs). Due to the fact that the most effective way to apply force to the ground, in order to run faster, is done vertically, this is highly important (Bosch). Loosely speaking, the arms help greatly in forcing the legs back down to the ground in an efficient manner. Even though sprinters were not used as the main subjects of the study, the same principles can still apply. On the treadmills used in the study, the runners were recorded at speeds of 3.8m/s,4.5m/s, and 5.4m/s. As speeds increased, so did muscular activation of the arms.Sprinters run much faster than this, but reasonable conclusions can still be drawn and applied from its these findings. As speeds increased, so did muscular activation of the arms.
Elite sprinters can exceed 12.6m/s during max velocity. Sprinting requires efficiently and quickly applying large vertical forces into the ground. One of the best ways to go about doing this better is by becoming stronger by way of strength training. The large amount of force production by the strong legs of a sprinter must be offset and managed by a complementary strong upper body. Running is the repeated application of force regardless of speed. For this reason, Hinrichs work is perfectly applicable to sprinters. Same concept, larger scale.
- Hinrichs, R.N. (1985). A three-dimensional analysis of the net moments at the shoulder and elbow joints in running and their relationship to upper extremity EMG activity.
- Bosch, Frans, and Ronald Klomp. Running: Biomechanics and Exercise Physiology Applied in Practice. Edinburgh: Elsevier Churchill Livingstone, 2005.