Racing Start Safety: Head Depth and Head Speed During Competitive Starts into a Water Depth of 1.22 m

The head depths and head speeds of swimmers attained following the execution of racing starts during competition have not been well described. To address this, 211 competitive starts were filmed into a starting depth of 2.29 m with a block height of 0.76 m. Starts were stratified according to age, sex, stroke, and swim meet. Dependent measures were maximum depth of the center of the head, head speed at maximum head depth, and distance from the wall at maximum head depth. Significant main effects existed for age for all three measures: F(1, 106) = 13.33, p < .001, F(1, 106) = 18.60, p < .001 and F(1, 106) = 70.59, p < .001, respectively. There was a significant age by sex interaction, F(1, 106) = 5.36, p = 0.023, for head speed. In conclusion, older swimmers performed starts that were deeper and faster than younger swimmers and nearly all starts exceeded the threshold speeds for injury. As compared to starts previously reported into 1.22 m, starts were deeper, slower, and farther from the starting wall at maximum head depth. When catastrophic injuries have occurred in competitive swimming, they are virtually all associated with swimmers impacting the pool bottom following the execution of a racing start (Mueller & Cantu, 2007). These incidents primarily have occurred during practice or warm-up prior to a meet and usually have involved some additional contributing factor(s). The injuries that swimmers incurred upon impact were commonly related to hyperflexion, vertical compression, and/or hyperextension of the cervical vertebrae and, as is true for all other diving injuries, impact with the pool bottom often has resulted in para- or quadriplegia (Albrand & Walter, 1975). From the perspective of safety, the extent to which water depth represents a component of the cumulative risk contributing to the catastrophic injuries in competitive swimming remains unclear. Obviously, head velocity, body trajectory (a primary determinant of head depth), body inertia, and other factors contribute to the severity of injury. Very little is known, unfortunately, about swimmers’ depths and velocities after the execution of typical racing starts into water depths meeting current regulatory requirements.