Wednesday, September 25, 2013

More on shallow water start dives - Pre-publication excerpt from the Journal of Aquatic Research & Education

A reader who has extensive knowledge on this subject has submitted a pre-publication excerpt from a research paper authored by Joel M Stager and Andrew Cornett that will appear in the Journal of Aquatic Research and Education.

Regarding shallow water mandates:

"...There are, however, two separate desirable outcomes of these water depth mandates:

(1) Having enough water depth to eliminate the chance of a swimmer hitting the bottom and...
(2) Lowering the chances of a swimmer being injured should contact with the bottom occur.

The second outcome seems to be the more achievable and certainly more realistic. With this in mind, we draw several conclusions.

The swimmers at the greatest risk for experiencing a catastrophic injury during the execution of a competitive swim start are the physically mature swimmers with limited practice and start experience. We make this conclusion based on two major findings. First, older, taller, and more massive swimmers have been repeatedly observed performing starts with greater maximum head depth and head velocity (Cornett et al., 2010, 2011). At the same time, swimmers lacking in competitive experience have been shown to be inconsistent in terms of controlling or modifying start depth (White et al., 2011; Cornett et al., 2012). This combination of deep, fast starts and a lack of control can have catastrophic consequences. Surprisingly, the younger, novice swimmers, in general, seem to be at a lower risk in this regard. The young, novice swimmers simply do not attain head depths and velocities great enough to place them at the same level of risk as equally inexperienced but physically mature swimmers. This is certainly not to say, however, that they are risk-free.

Next, we conclude, similar to previous authors on this topic, that the empirical evidence suggests that the current minimum depth of 1.22 m needs further careful consideration. It appears that there is very little margin for error at this depth, particularly for the older, physically mature swimmers due to their depths and velocities. A significant number of swimmers closely approached the pool bottom at this depth (Cornett et al., 2010) such that the potential for contact appears unacceptably high. Unfortunately, data from competitions held in 1.52 m (5 ft) are not yet available making firm recommendations on “how deep is deep enough?” difficult. "

It is certainly possible to require deeper minimum pool water depths than what is called for by current regulations. Doing so would likely help to reduce the risk of injury due to pool bottom collisions during the swim start. The studies presented in this review lead directly to this conclusion. However, while the risk can be minimized, increasing minimum water depth within the range of feasible water depths cannot eliminate it.

Our study of ‘worst-case scenario’ swim starts demonstrated that the potential for catastrophic head and neck injury existed at water depths as deep as 2.5 m (Stager et al., 2013). Thus, changes in minimum water depth requirements are less a matter of eliminating the possibility of contact and more about learning how to reduce the incidence of contact and severity of injury through coach and swimmer training and education. ..."


Anonymous said...

Two other possibilities.

1. Assuming most issues are with pools that won't have major competitions (high schools, summer clubs, etc.) why not allow a meet where swimmers start from in the water. Not optimal but still allows pool to be used for competition.
2.Since swimmers in the U.S. need to have training on starts teach them both a deep and shallow water start and allow only shallow water starts in shallow pools. Its essentially why these pools were fine for everyone else for 50+ years. Once the start evolved it became an issue. Also could take out blocks and start from pool edge.

Again, this would only be for lower key competitions.

Tony Austin said...

If I ever race at the Janet Evans pool in Fontana and I have to start in the shallow end I am diving off the deck instead of the blocks.

I'm 6'2 and I weigh 190 pounds and diving into the shallow end there during an IM relay was not fun.

Wen I dove in and up to the surface my feet dragged across the bottom and as a reaction to it I dolphin kicked three times. (My relay swim was the breaststroke) I presumed I was disqualified so I swam slow in case they missed it. (They did)

Anonymous said...

For the future, pool design. We always think of pools as having a shallow end and a deep end. But our school district pool is 7' at both ends and 4' in the center. It was built to have 2 areas for water polo, but it's a great solution for safety.