Did my first LT (Lactate Threshold) test Saturday with Stan Watkins of Vision Quest Coaching. LT is one of the key determinants of endurance performance, so tracking your LT helps in designing a training program. Following a program that works you at or slightly above your LT should help increase your LT - and thus improve your endurance performance.
The testing involved riding my bike in a computrainer for 40 minutes and trying to generate the highest average wattage over that time period.
Result for the 40-minute LT: 284 watts.