Triathlon Swimming Q&A: Exhaling through Mouth/Nose

January 11, 2010

Q: Are some pools “faster” than others and should I care as a triathlete?

A: The short answer is, yes, pools are different. But a triathlete should not care. Here are some things that make a difference in the speed of a pool:

1. Gutters – gutter systems that can absorb waves effectively are going to allow swimmers to go faster. A smaller wave means less resistance when a swimmer does a flip turn and starts the next lap. A pool without gutters creates many waves, which bounce off of many walls and creates a chaotic and choppy surface.
2. Lane markers – In general, a thicker lane marker (like a wave-eater) will absorb more waves (like the gutter). Having several thin lane lines will produce the same effect.
3. Altitude – a pool at altitude will produce slower times for the longer distance events. Unfortunately, the water doesn’t decrease in density too much and so high altitudes will not help in sprint distances.
4. Additives – If the pool is salt water, it will be faster than if it were filled with fresh water (because the salt water is less dense).
5. Temperature – the optimal pool temperature for racing is between 75-77 degrees F. Any hotter or colder will impact race times.
6. Water jets – A pool with water jets on will be slower than if they are off (unless you luck out on a 1-length sprint in the direction of the jet!).
7. Walls – A pool with rough walls will allow swimmers to go faster by pushing off the wall harder, without fear of slipping.
8. Depth – A deeper pool will absorb waves better than a shallow one. A depth of 7 feet or more is best. If the depth is 4 feet or less, there is risk that some swimmer’s hands will hit the bottom.

As you might guess, the net effect of all of these factors is small (measured in tenths of seconds over 100 meters). So, for the triathlete, the difference is minimal. You will pretty much get the same workout in regardless if you train in the fastest pool around versus the neighborhood pond. So, swim at a pool that is most convenient for you, and don’t worry about how it will affect the times.

View previous triathlon swimming tips.