I missed a couple of points in the last post, one which I've been meaning to write about for a while.
Charts and graphs
There are a multitude of formulas and graphs people have come up with to compare race performances. The gold standard remains the Gardner-Purdy charts from 1970, which are surprisingly accurate for the majority of runners (the 8K and 1/2 marathon times are all about 2 seconds per mile slow, due to these races being rare in 1970 and wildly popular now, but that's still remarkable). These charts are available in some form in a lot of places - I have five training books that contain some version of them - and can be found, probably illegally, on the web.
Jack Daniels has his own chart in his book. I find it to predict much too fast for long races and too slow for short taces, but I think it works well for those whose primary race distances are 1/2 marathon and beyond. If you run a 5K or 10K and look up the corresponding marathon time, you probably can run that time with appropriate training.
But how can you predict a race time if you haven't been racing? In Minneapolis, there's a 5K every weekend for 9 months of the year, but when I lived in rural Indiana, there were only two local races each year. Sometimes one needs to use workouts rather than races as a guide.
Race prediction by workout is mostly done for the mile and the marathon, one because the races are rare, the other because one does them infrequently.
For the mile (and I know no one reading this cares much), 8 to 10 quarter miles (400m) on the track done with one minute rests can usually be done at one's current mile pace. Alternatively, 8-12x200m with 200m recoveries at roughly 1/2 marathon pace also works. Many milers find that they can do 1200m on the track at the pace they can race a mile in a workout.
For the marathon, a number of methods are used. Some of these are taken from sources I've forgotten, or I'd attribute them. If one takes one's average pace for all runs and subtracts one minute per mile, that's about marathon pace; skipping the fast workouts, easy training pace minus 1.25 minutes per mile is marathon pace. An all-out mile on a track times 1.3 gives one's marathon pace. If one runs 8-12 miles at normal training pace, then runs another 3-10 miles with each mile faster than the one preceding it, the last 6-10 miles average about marathon pace.
Lastly, there's the Yasso 800's, which have become very popular for marathoners lately. Yasso discovered that if one ran ten half-miles with an rests equal to the times run, the average time is about the same as one's marathon finish time (using min:sec and hr:min, respectively); I actually found the same thing independently, looking through charts in "Computerized Running Training Programs" by Gardner and Purdy. It usually predicts a little fast, but is close. The problem I have with this particular workout is that people are looking at it in the wrong way; they want to run a 4:00 marathon, so they run 4:00 800's and quit after doing three to five of them. The workout isn't specific to training for the marathon, so it shouldn't be used that way, but one should actually do all ten half-miles, no matter how slow the last few are; the average tells one what one marathon time one should be training to do.
Any workout on a track can be used as a benchmark, but one should do the same one a week or two before every race. This way, one can compare workouts and better predict how one will race based upon fitness.
5 days ago