While appearing on the Triathlon Summit, I also described the difference between a "pool stroke" and an "open water stroke."  The stroke you’re likely to develop while training in a 25-yard pool is distinctly different from the stroke that will bring the greatest success in open water.

The realization came from my own experience but was confirmed when I read an on-line article by Jonty Skinner, the Performance Science Director for USA Swimming

Skinner — as had many others — noted that some swimmers who were highly successful in SCY races (conducted in 25-yard pools) were far less successful in LCM races (conducted in 50-meter pools). Success in LCM is critical because the Olympics and World Championships are conducted in 50-meter pools.

So Skinner tried to analyze the differences between successful LCM swimmers and SCY swimmers who performed poorly in 50-meter pools. He began by pointing out that in both courses a swimmer will alternate among three activities – swimming, turning, and underwater gliding/kicking.

Among elite swimmers, in a 25-yard pool, the ratio of swimming to non-swimming time is just over 2.5 to 1. In a 50-meter pool, the swimming to non-swimming ratio rises to nearly 8 to 1.

When he studied their strokes  on video, Skinner saw that the most successful "Long-Course" swimmers tend to swim freestyle with a distinctly different technique than those successful in short-course pools. LCM swimmers had longer, slower strokes, and a recovery, entry and catch that create a strong connection between hip drive and armstroke.  SCY swimmers swam with a more aggressive, high-turnover stroke with less body rotation, but higher arm forces.

As Skinner explained, a faster stroke with high arm forces can generate more speed in short bursts, but leads to fatigue more quickly, compromising its effectiveness for sustained swimming. A high-speed, high-force stroke may be advantageous in 25-yard pools because top swimmers spend relatively little time swimming. During a minute of Short Course racing, an athlete could spend as little as 43 seconds swimming and 17 seconds "not-swimming." The time they spend turning and pushing off allows them to recover from relatively brief bursts – often just 10 to 12 seconds — of aggressive stroking. In a 50-meter pool, that swimmer might spend 53 seconds of each minute swimming and only seven seconds "not-swimming," necessitating a more economical way of swimming.

I instantly recognized that what was true for 50-meter pools would become hugely compelling in open water, where "not-swimming" recovery opportunities disappear. The complication is that most open water competitors do the majority of their training in 25-yard pools and successfully adopting this new technique will require a conscious decision to swim differently — i.e. to be willing to sacrifice some short-term speed to practice an Open Water stroke. Here’s video of me demonstrating the Open Water Stroke. This is excerpted from our new DVD Outside the Box.