Measurement of impacts in football

Actual impacts encountered by players were measured by telemetry during regulation football games. These data confirmed the fact that the manner of response to the blow rather than the blow itself determines the injury potential. Impacts to inanimate objects or to the heads of anesthetize animals produce experimental data that are simplified by the fact that the involved masses are constant and the contact time is negligible. On the football field, the players are tense at the snap of the ball and this resistance causes variable acceleration, variable forces, variable velocity changes as well as varying masses involved in these collisions. These measurements show that impacts on the field can not be compared with impacts involving bodies which are incapable of response. For example, a helmet under the test conditions of the laboratory is unable to withstand 90 ft lb of energy but the same helmet on the football field is exposed to far more energy when one considers that a 224 lb athlete with a speed of 100 yards in 10 s will deliver 3150 ft lb of energy. How such energy can be absorbed on the football field is demonstrated in this study by the physiologic response of the athlete alert to impending blows.