Racing Start Safety: Head Depth and Head Speed During Competitive Swim Starts into a Water Depth of 2.29 m

Self Cite

To expand upon previous studies showing inexperienced high school swimmers can complete significantly shallower racing starts when asked to start "shallow," 42 age group swimmers (6-14 years old) were filmed underwater during completion of competitive starts. Two starts (one normal and one "requested shallow") were executed from a 0.76 m block into 1.83 m of water. Dependent measures were maximum depth of the center of the head, head speed at maximum head depth, and distance from the starting wall at maximum head depth. Statistical analyses yielded significant main effects (p < 0.05) for start type and age. The oldest swimmers' starts were deeper and faster than the youngest swimmers' starts. When asked to start shallowly, maximum head depth decreased (0.10 m) and head speed increased (0.32 ms -1 ) regardless of age group. The ability of all age groups to modify start depth implies that spinal cord injuries during competitive swimming starts are not necessarily due to age-related deficits in basic motor skills.The safety risks associated with the execution of a competitive racing start are due to several factors. Some of these are under the swimmer's control and some are not. For example, the trajectory of the body upon leaving the starting block, the velocity at which the body is traveling, and the depth of the head during the trajectory are to a large extent determined by the swimmer or the physical body characteristics such as mass and strength. Block height and water depth, in contrast, are a function of the facility and regulatory requirements. If a swimmer comes into contact with the pool bottom, the severity of the injury that occurs is influenced by the swimmer's momentum, primarily a function of the velocity and mass of the swimmer. The swimmer's velocity is related to the forces generated by the swimmer while on the block, the swimmer's ability to reduce the resistive forces (streamline) once entering the water, and the height of the block above the water surface. The execution of a safe racing start therefore requires the swimmer to exhibit a complex blend of motor abilities, including such skills as static and dynamic balance, multiple axial movements, and ballistic locomotor skills.

Section: Head Speed At Maximum Head Depth and A Request To "Start Shasupporting

confidence: 89%

Section: The Effect Of Age On Racing Start Parametersmentioning

confidence: 99%

Start Depth Modification by Adolescent Competitive Swimmers

Cornett¹,

White²,

Wright³

et al. 2012

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“…While it is certainly conceivable that a swimmer in this group could contact the pool bottom during the execution of a competitive backstroke start, from these data, this would appear to be unlikely. In terms of relative risk, given the greater depths attained during backstroke starts by the older swimmers, they appear to be at a greater relative risk than their younger counterparts as has been previously reported for forward starts from a block (Cornett et al, 2010(Cornett et al, , 2011.…”

Section: Maximum Depth Of the Center Of The Headsupporting

confidence: 56%

Racing Start Safety: Head Depth and Head Speed During Competitive Backstroke Starts

Cornett¹,

White²,

Wright³

et al. 2011

Self Cite

Research on competitive swim start safety has focused on starts involving a dive from above the water surface. The purpose of this study was to determine the depths, speeds, and distances attained when executing backstroke starts, which begin in the water, and to investigate whether or not these variables are a function of age. Backstroke starts (n = 122) performed in 1.22 m of water during competition were stratified according to age group (8&U, 9-10, 11-12, 13-14, and 15&O). Dependent measures were maximum depth of the center of the head (MHD), head speed at maximum head depth (SPD), and distance from the wall at maximum head depth (DIST). Main effects were shown for age group for MHD (F = 8.86, p < 0.05), SPD (F = 4.64, p < 0.05), and DIST (F = 17.21, p < 0.05). Because they performed starts that were deeper and faster than the younger swimmers, the older swimmers seem to be at a greater risk for injury when performing backstroke starts in shallow water.The racing start may be the aspect of competitive swimming that is the most inherently risky. In support of this, a study spanning a 25-year period reported 13 catastrophic injuries resulting in "permanent severe functional brain or spinal cord disability" within competitive swimming (high school and college) with all but one incident occurring during the execution of a racing start from a block (Mueller & Cantu, 2007). As a result, examination of the various parameters pertaining to the racing start, as a means of identifying the level of risk these factors represent, seems appropriate. Variables that are relevant in this regard primarily relate to the depth and speed swimmers attain during the execution of racing starts. These two variables dictate to a large extent the inertial forces generated during a start.Of the four strokes contested in competitive swimming events, three (freestyle, butterfly, and breaststroke) utilize a starting block and involve a forward dive from above the water surface and one (backstroke) is executed from within the water. To date, research on racing starts has focused exclusively on forward block starts and

“…Statistical analysis revealed that head speed for racing starts from the standard (0.76 m) starting height and the pool deck both were significantly greater than for starts from an intermediate starting height (0.46 m) despite being deeper than those from the intermediate block height. This finding was unexpected as previous research had demonstrated that shallower racing starts are either consistent with greater head speed at maximum head depth (Cornett, White, Wright, Willmott, & Stager, 2011a;Cornett, White, Wright, Willmott, & Stager, 2011b;White, Cornett, Wright, Willmott, & Stager, 2011) or no difference in head speed at maximum head depth (Blitvich, McElroy, Blanksby, Clothier, & Pearson, 2000;Cornett, White, Wright, Willmott, & Stager, 2011c).…”

Section: Head Speed At Maximum Head Depthmentioning

confidence: 75%

Block Height Influences the Head Depth of Competitive Racing Starts

Cornett¹,

White²,

Wright³

et al. 2011

Self Cite

The purpose of this study was to determine whether or not starting block height has an effect on the head depth and head speed of competitive racing starts. Eleven experienced, collegiate swimmers executed competitive racing starts from three different starting heights: 0.21 m (pool deck), 0.46 m (intermediate block), and 0.76 m (standard block). One-way repeated measures ANOVA indicated that starting height had a significant effect on the maximum depth of the center of the head, head speed at maximum head depth, and distance from starting wall at maximum head depth. Racing starts from the standard block and pool deck were significantly deeper, faster, and farther at maximum head depth than starts from the intermediate block. There were no differences between depth, speed, or distance between the standard block and pool deck. We conclude that there is not a positive linear relationship between starting depth and starting height, which means that starts do not necessarily get deeper as the starting height increases.There is a prevailing belief that competitive swim start depth increases with starting block height despite limited valid data to support such a notion. In fact, this belief is so prevalent that it has been incorporated into the rules of the sport. The National Federation of State High School Associations (NFHS), the governing body of high school athletics in the United States, does not allow swimmers to execute competitive racing starts from a starting block when the water depth is less than 1.22 m (4 ft), but they do allow swimmers to complete a racing start from the pool deck when the water depth is between 1.07 and 1.22 m (3.5 and 4.0 ft). In enforcing this rule, it would appear that the NFHS is operating under the assumption that competitive racing starts from the pool deck result in shallower starts than those from a standard starting block. To our knowledge, this hypothesis has not been adequately tested.Competitive racing start depth is an important issue given the potential for serious injury if the swimmer impacts the pool bottom. Mueller and Cantu (2007) reported that all but one of the thirteen catastrophic injuries resulting in "permanent