The current IAAF Track and Field World Championships and the 800m final inspired me to reflect on Alberto Juantorena' unusual 800m/400m gold medal "double" in the 1976 Olympics in Montreal (Youtube video). Up until 1976, "El Caballo" specialized in the 400m; however, his Olympic winning time set a new world record in the 800m. In spite of Juantorena's bold success, no successful 400m runners have explored the 800m waters. Instead, 800 races are filled with middle distance runners at the bottom of their distance and not-so-successful 400 runners moving up.
Jeremy Wariner, currently injured, is the most obvious candidate to make the jump. He won gold in the 400m at the 2004 Olympics and ran a 43.45 in the 2007 World Championships, the 5th fastest time and 3rd fastest person ever. Since then, however, LaShawn Merritt has defeated Wariner in the key Olympics and Worlds races (albeit under the cloud of drugs) and Wariner came up injured before this year's Worlds. While just slightly taller than world record holder Michael Johnson, Wariner is much lighter, officially over 20 pounds lighter which matters in a longer race.
What kind of time might Wariner run? To generate some quick estimates, I collected data on the best 400m and 800m times for some of the best runners ever in the 800 who also have personal best 400m times listed somewhere (IAAF site, Wikipedia, All-Time Best) : Juantorena, Sebastian Coe, Andre Bucher, Wilson Kipketer, and David Rudisha. Among these, Juantorena is the only "moving up" runner whose main focus had been the 400. His ratio of best 800 to best 400 is 2.33. The others focused on longer races and happened to run a recorded 400m at some point. Their 800/400 ratios are Coe (2.16), Bucher (2.21), Kipketer (2.15), and Rudisha (2.21). At the top end of 2.33, Wariner's predicted time would be 1:41.3 or only 0.3 above the current world record. At a multiple of 2.2, his predicted time is 1:35.7, likely well below what is attainable.
To bring more data to bear on this, I expanded the races to generate 1600-800 ratios (converting 1500m times to 1600m equivalents) along with 400-200 ratios, identifying athletes as to whether they were racing "up" or "down" from their best distance or distance of main focus (neutral means they were very successful at both distances):
1600-800 (Up): Bucher (2.27); Kipketer (2.35)
1600-800 (Neutral): Coe (2.20)
400-200 (Up): Usain Bolt (2.33); Tyson Gay (2.29)
400-200 (Down): Wariner (2.15); Quincy Watts (2.12); Merritt (2.20)
400-200 (Neutral): Michael Johnson (2.23)
The figures suggest that the multiples for moving up are generally higher than moving down. Using the "up" data, Wariner's predicted times would range from 1:38.7 to 1:42.2, putting him right at the head of the pack of current 800m runners, including World Record Holder David Rudisha (1:41.0). The multiples for truly unique runners such as Michael Johnson and Sebastian Coe who focused on multiple distances suggest that Wariner's time might could be pushed very low if he specialized his training.
A related topic is what kind of time could Usain Bolt run if he focused on the 400m one day. As a teenager, he ran 45.2. In 2010, Tyson Gay ran 44.8 making him the only person ever to run sub 10-second 100m, sub 20-second 200m, and sub 45-second 400m. Of course, his time might be lower with more specific training directed toward the 400. If Bolt could approach Michael Johnson's multiple of 2.23, his predicted 400m time would drop below the 43-second mark.
Finally, in discussion over the year's with WKUs Cross Country and Track coach, the issue of weight often crops up. For example, this along with his relatively short legs are often cited as reasons why Michael Johnson, in spite of his incredible speed and endurance, likely wouldn't run a great 800m. Collecting data on heights and weight suggests that Wariner's and Bolt's weight per height ratios make them strong candidates to move up. Interestingly, Juantorena's weight to height ratio is second highest in this elite group; of course, he also had incredibly long legs, but I don't have a measure of that across the athletes.
Athlete Weight-Height Ratio (Kg/meters)