Tinman
Lactate Threshold pace is about 8% slower than your 5k/3-mile pace. If you run 5:30 per mile (330 seconds), for example, then your LT is 330 x 1.08 = 356.4 seconds or 5:56.4. You can run a local race and then use the pace from it to calculate your LT. Otherwise, just ran at a strong effort, but slower than 5k pace. Make sure your breathing is not labored. I also suggest that you work on the Aerobic Threshold, which occurs at a slower pace than LT. Just add 1 minute per mile to your current 5k pace. For a high schooler, run 6-8 mile runs at this pace once or twic per week. Do striders to improve your leg speed, but not more than 600m worth total. For example, you might run 6 x 100m striders with 200m jogs. Tinman