The other threshold is your aerobic threshold. However, your lactate threshold is only one of the thresholds that matter. In that case, you will burn too much muscle carbohydrate, accumulate lactate/acidity, and subsequently build fatigue too quickly, which will have you hitting the wall before the race end.

Suppose your threshold is slower than 4min/km (6:26min/mi). Unless you’re running on a treadmill, you NEED to be capable of running 4:10min/km (6:42min/mi) without going over your threshold. Your sub-3hr target pace is 4:16min/km (6:52min/mi), which means your 1km/1mi splits will drift between 4:10 – 4:20min/km (6:42 – 6:58min/mi). If you cannot run a sub 40min 10km, you have next to no chance of running sub 3hrs. You want to have a threshold of around 3:50 – 4min/km (6:10 – 6:26min/mi), which is about a 39min 10km or 1:26min half marathon. The first number you need to look at is your threshold pace.

Here’s what you need to be able to do for a sub-3hr marathon goal to be realistic. Is that realistic?” They’re often concerned they might have left it too late. They come to me and say, “I want to run sub 3hrs.

A large pool of runners I work with are 35-45 year old working professionals. I hear the 3hr marathon goal thrown around A LOT.

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