I have been training all winter for my first half-marathon which is coming up soon. During my triathlon season last summer and cross-country running last fall, I did well by monitoring my heart-rate (HR) during the races to set up good, sustainable pacing. I'd like to do the same in this race, but don't really know what zone I should be shooting for. I'm guessing low zone 3, no more for the first 8-10 miles, and then bump it up to mid or even upper 3 if it seems right . My zone 3 by BT Lactate Threshhold test is 131-137 bpm...I'm pretty old. What do you think?
One of the hardest races to ‘pace’ is a half marathon. We know a 5k is pretty much a ‘best effort’ type of race, and that a 10k is only slightly slower – usually 10 seconds a mile or so. A marathon is usually run at long run pace, as it has to be sustained for 3+ hours. But a half marathon can be pretty tough to decipher. We’ll give it our best shot here.
You have the right idea with your pacing plan and I’ll even take it one step further to help you. I’ve used the following formula many times with great success I might add, and it’s about as easy as it gets. I call it the 5/5/5 plan. 5 miles at Zone 2 HR, 5 miles at Zone 3 HR and then 5k at your absolute best effort. If you can run the first 10 miles at the appropriate paces, then you’ll run about 20 seconds off your 5k personal best in the last 5k of the race.
If your lactate threshold is 134 (the middle ground between 131 and 137), then your Zone 2 heart rate for the race would be 109-118; for Zone 3 your heart rate would be 119-134 and then finally as you’re pushing hard for the last 5k, really crank it up and you should be in the 134-140 range.
Part of racing well is also having a good taper for the race and also a good nutrition plan. You may get advice that you don’t need any calories or fluids during a half marathon, but I’ll disagree with that. Knowing that you can handle 200 calories (or whatever you can personally handle) an hour (4 cups of Gatorade or 2 gels) will help keep your energy levels up. As you start to push more, especially later in the race, you don’t want to be on fumes, so make sure as the easier miles (1-5) are ticking by, you are keeping up with calories. Trying to take in calories as your heart rate is nearing threshold, may not be the easiest thing to do.
Lastly, if you have time, you can certainly test this plan out in training. You could run something like 10 miles and break it down to 4 / 4/ 2 or even if you ran 7 miles, it could be 3/ 3/ 1. The key is sticking to your zones early (and it will feel like you are holding back quite a bit), and then being able to execute the faster running towards the end. Good luck to you and have a great race!