All endurance athletes are familiar with the term VO2 or VO2max. We know elite endurance athletes have high VO2max, whether it is Lance Armstrong (84 mL/kg/min) or Steve Prefontaine (84.4 mL/kg/min). VO2max is the maximal amount of oxygen in liters the body can transport and utilize during exercise. Swimmers VO2max can be assessed outside the pool (running/biking), but performing this test with a different stimulus can stress the body providing invalid results. Therfore, we do not know many swimmers VO2 maxes while swimming. This is due to a variety of reasons, the most notably it is hard to measure! Runners or bikers are able to go to any exercise physiology lab to test VO2max, but measuring this volume in the pool is near impossible, but not impossible.
One study looked at the validity of measuring VO2max during breaststroke with the device in the above video. This study deemed VO2 measurements variable with relative errors observed especially in high intesity swimming. I would attribute this to the length of the measuring tube which is known to have correlation with error. VO2max is an essential variable of all aerobic and anaerobic training, unfortunately swimming's technology is behind preventing optimal performance. Don't get me wrong, I know VO2max can be estimated with a line best fit of swimming velocity and heart rate, but the accuracy and availability of proper testing procedures is scarce. Does the Olympic training center have a similar VO2max set up with the flume/endless pool?
1. Reis V, Marinho D, Barbosa F, Reis A, Guidetti L, Silva A. Examining the accumulated oxygen deficit method in breaststroke swimming. Eur J Appl Physiol. Apr 2010.