I think a sprint workout with samples after the final rep is pretty revealing (with the caveat that the volume of sprints will change the result).
WORKOUT: 6x 8″ all-out uphill sprints with 3′ PASSIVE rest after each rep.
* I usually sit for the first two minutes right after the sprint, and then slowly walk back down to the start in the third minute. It’s important that the rests are passive so that you don’t have active muscle reabsorbing lactate.
* I would make sure you do these uphill unless you have a track history. It’s too easy to get injured doing all-out sprints on a flat course. The range of motion when sprinting uphill is less extreme, so less likely that you’ll pull something.
* Make sure you warm up well before the sprints.
* If you just wanted a test without the workout, you could do a Jan Olbrecht approach of one interval of 45″-90″ as hard as you can.
TESTING: After either method, sit immediately after the last interval. (Put on a jacket if it’s chilly because you’ll be there a while). Test lactate at two-minute intervals starting on the third minute until you see lactate decline. So samples would be at 3′, 5′, 7′, etc.
According to Steve Magness:
“The lower the lactate levels, the more slow-twitch, while the opposite is true for fast-twitch. As a guideline a readinf 6 or less and you about as ST as you can get. Between 6 and 9 you are predomanantly ST. Anything between 10 and 14 and yopu have a mixture. Between 14 and 128 and you are more likely in the FT group, and anything above around 19 and you are deifntiely in the FT group.”
~ The Science of Running, p. 210
Note that training history and volume will affect the results. When I started doing these I could get between 10 and 12. With similar training volume (~500 hours), but consistent volume of sprints in my program, I got up to 23. Then with more volume (~700+ hours), it dropped to 14.
So… lots of variables! But if you test consistently, and note how your volume could be affecting the results, you should get a pretty good idea of what type of athlete you are.