Leaps and Bounds of a Watery Kind
Something a bit different today.
Just a chart showing the progression in the men's 1500 metre swimming world record since records began for the event over a century ago for long course, i.e. 50 metre pools.
The data is from this Wikipedia link
Nothing really specific, other than to post up an example of the way progression in performance has occurred over a century has not been linear nor predictable in other ways but rather occurs with quite different rates of improvement. It was prompted by a discussion about, you guessed it, using past performances (i.e. cycling mountain ascent times) or the ubiquitous estimations of power to body mass ratios as a means to calibrate a modern day "dopeometer", which is of course a path fraught with problems.
Lasting of the order of 15 to 20 minutes, the elite 1500m swim is an event dominated by an athlete's aerobic metabolic capabilities, their morphology and water drag characteristics and with quite a deal of technique/form involved, e.g. making best use of turns, and there are far more degrees of freedom of movement than say pedalling bicycle cranks permits.
Looking at the chart we can see rapid improvement occurred in the 1920s, then only gradual change until the late 1950s when there was a consistent and significant rate of improvement for 20 years through until the late 1970s. I'm guessing improved access to suitable facilities enabling more athletes to compete played a big role in helping to drive this rapid change, along with presumably improvements in training, technique and so on.
Since then the improvement has been far more incremental despite the 1990s and 2000s being the EPO era and the 2000s the era of the swimsuit technology wars. What I haven't done though is to consider the change in power demand for these more incremental performance improvements, i.e. does a small change in speed require a significant change in power? I am presently not well versed in how linear or curvilinear the speed versus power relationship is for swimmers. No doubt there has been plenty of research into this.
Of the 46 new world records plotted, 28 (61%) were by American or Australian swimmers. The only "eastern bloc" athlete in this list is Vladimir Salnikov of the former Soviet Union with 3 records set in the early 1980s. Current world record holder is Sun Yang of China with his swim at the 2012 London Olympic Games.
Edit to add:
After Charles' comment about looking at other shorter swimming events - I plotted the progression with the 400 metre world record as well, and overlayed the two - and adjusted the time scales so the relative progression can be directly compared.
A broadly similar pattern, which is not surprising as you'd expect similar means of performance improvement, but the progression with the 400m event is more consistent than for the 1500m event.
The 400m swim, from a energy demand perspective, is similar to cycling's individual pursuit, and I'd expect roughly one-quarter to one-third of the energy demand is met by anaerobic metabolism (compared with say 10% for the 1500m), the balance of course supplied by aerobic glycolosis.