How the System Works

A CROSS COUNTRY PERFORMANCE BECOMES UNIVERSALLY UNDERSTANDABLE ONCE CONVERTED TO ITS TRACK EQUIVALENT

A course difficulty rating is found by first measuring how much energy a runner expends to maintain a certain constant speed for an exact distance on a track, then measuring again how much more energy the same runner expends to maintain the same speed for the same distance on an accurately measured cross country course in similar conditions.

Ratings of difficulty are simply the differences in energy costs as measured and compared in controlled running tests between a universally recognized standard and a given cross country course. That universal standard, to which every other course is compared, is a synthetic surfaced 400m track which is found anywhere, is the least difficult cross country course available, and which has a consistent length and surface. Unlike cross country courses, performances on tracks have universal meaning because all tracks are the same design. Any competitive runner knows for example what it would mean to run a 25:57 8k or an average of 5:11 per mile for five miles on a track. An identical effort that day by the same athlete on any other track in similar conditions would also produce roughly the same time. But what would that 8k track effort, or put more precisely, what would an identical amount of energy have produced if it had been run instead on the very difficult Van Cortland Park or the relatively easy Ga. State cross country course in similar conditions? ON COURSE RATING SYSTEMS TM researchers measured the energy it took runners to do just that.

Through laboratory testing of subjects as well as running tests on courses and tracks at constant sub maximal speeds over identical distances in similar weather conditions, the differences between the energy used on tracks and then again on accurately measured courses were compared. Those differences reflect the difficulty of the course. For example, if it took 3.64% more energy on average for subjects to maintain a certain constant speed on a course (9.28mph in the case of the Ga. State subjects) than it took the same runners to run the same speed and distance on a track, then that course would have a difficulty rating of 3.64. A 3.64 course rating also means that a race performance on that course would be slower by close to 3.64% more seconds than an identical performance (equal energy) would produce on a track by that athlete in similar conditions. The actual differences in time (or velocity) relative to each rating are coded as CV (% change in velocity). This change in velocity (CV) reflected in minutes and seconds is what the calculator shows you when comparing performances.

Take Adam Brunfeldt's 26:48, which was run in pleasant dry conditions on the 3.64 rated 7988 meter Ga. State course at the NCAA D-III regional meet in Nov. '03.  According to the calculator, his track equivalent 8k time (corrected for length) would be 26:01. Using the calculator again, we see that if he ran with equal energy in similar conditions on the 6.59 rated 7998 meter Van Cortland Park course, his time would have been 27:24, ten seconds behind Johnson's actual time at VCP (27:14) which was run in soggy conditions through 6-inch-deep puddles. So even though a 26:48 at Ga. State looks at first like a more competitive performance, the calculator shows us that because Van Cortland is so much more difficult, a 27:14 on VCP was clearly a better race even if the weather conditions had been similar. To demonstrate this further, if you use the calculator to find the track equivalents of these two performances you would see that a 26:48 at Ga. State would be a 26:01 on a track and a 27:14 at VCP would be a 25:52 if run in similar conditions.

Three reminders are in order. The first is about weather conditions. Remember that the calculator will tell you what a performance on a rated course would be on another rated course or track if run with equal energy in similar conditions that day by that athlete. It is important to remember that calculated equivalences will be accurate in the most similar conditions but as conditions become less similar, calculated performances become less equivalent, just like apparently identical track performances run in greatly dissimilar conditions. Soon, ON COURSE RATING SYSTEMS will include a weather/surface adjustment to the calculations, and in time, weather conditions will become a regular part of published race results.

The second thing to remember is that this system, though it often does so quite well, is not meant to be a predictor of future performances. It will accurately show what one performance would be if run on another course or track with equal effort, or more precisely, an equal amount of energy. Injuries, illness, motivation and other performance influencing factors which change from one week to the next are all part of the game but not components of the calculator. The calculator is only telling you what one performance's equivalent would be on another course or track if run with the same energy, motivation, injuries, etc.

Lastly, remember that this system is still in its developmental stages, like an early model T automobile. Many refinements, like the weather/surface adjustment and improved accuracy through accumulation of statistics, await, but this long overdue tool actually works and is a big improvement (for making sense of race performances) over what we have relied on until now.......intuition.

GO TO "How to Use the Calculator".