Lessons from a Half Marathon Time Trial: Don’t Go Out Too Fast

Two feet, with white running shoes, and a tired runner sitting down.

When I started running again earlier this year, my goal was to survive until the end of the year without getting injured and (hopefully) run a half marathon.

Well, I made it to the fall injury free. And last weekend, it was finally time for the half marathon time trial that I had put on my calendar.

So how’d it go?

Keep reading to hear about my preparations for the time trial, the half marathon itself, and some lessons learned.

Preparing for a Half Marathon Time Trial

If I had it my way, I’d be running this race with a group of other people. But alas, Covid had other plans. There are a few small runs happening near me, mostly trail runs, and my only option for a half marathon was to do it myself.

Picking a Route for my Half Marathon

First up, I had to plan a route. I didn’t want to have to drive anywhere, so I was mostly focused on routes around my house.

There’s a long run that I like to do through a county park, which is around 6-7 miles. I could have done that route twice to finish. But it includes a pretty steep incline, and I didn’t want to have to battle that. There’s also a traffic light in the middle of the route, and I was trying to avoid any reasons to stop.

Instead, I chose a three mile loop on the suburban side streets near my house. There are a few gentle hills – you can’t run anywhere near my house without some hills – but nothing too crazy. I didn’t have to deal with traffic lights or traffic. The downside was that I’d have to do 4 and a half laps to finish the race, but c’est la vie.

Fuel and Water for My Half Marathon

Next up on the list of things to plan for was nutrition and water.

Another thing I liked about this route was that it started and ended at a local park. I figured I could easily stash a couple bottles of water there, and drop the empties, if I needed them. I’d go back through the park at the end and be able to dispose of any trash.

As it turned out, it was a cool day. The temperature was in the low 50’s when I set out late in the morning. It had rained all night, and there was a light mist going. Given the weather, I decided not to bother with water for the run.

I always train fasted, and I’d done 12 miles in a training run without any food, so I thought I would be ok without anything to eat along the way. I did make sure to eat enough carbs leading up to the race to keep my fuel stores topped up. And the morning of, I ate a nice big bowl of yogurt with some fruit. I hoped that would get me through to the end.

My usual pre-run routine includes a cup of coffee and a visit to the bathroom. I planned to do the same that morning.

Planning my Half Marathon Pace

I spent a good deal of time – probably too much – thinking about what pace to run and what time to try for. All told, anything under two hours would have been fine.

My old half marathon PR was 1:54, so part of me wanted to beat that. I put in more miles this year, compared to the last time I ran a half. I knew I was in better shape, and this was in reach.

Then again, based on my recent 5k (24:30) and 10k (50:00) times, I thought I might be able to do much better. Plugging my times into a race equivalency calculator suggested I could be capable of something in the neighborhood of 1:52.

Ultimately, I decided that my plan would be to start out conservatively – 9:00 to 8:45 per mile. If I averaged 8:45, that would get me to about my previous PR. But if I felt good after the first couple miles, I could easily pick up the pace and bring my time down.

Running the Half Marathon Time Trial

With all of my preparations done, it was time to set out and run. I ate my breakfast, drank my coffee, cleaned out my e-mail box, queued up a couple hours of podcasts and headed out the door.

Warming Up for the Half Marathon

To warm up, I jogged to the park where my route would start. Taking the long way there, this was a little over a mile. This was enough to get my heart rate up a bit, but hopefully tire me out too much. After all, I still had 13 miles to run.

I walked up to the bleachers by the baseball field and did some leg swings. Next up were some lunges. I rounded things out with a few drills. Lastly, I did a few sets of strides. I tried to approximate my goal race time, but I think the pace on the strides was a little faster than I wanted.

After the last set of strides, my legs felt good. I was awake and warmed up. My heart was pumping a bit, so I took a walk up to the street corner where I’d start, and let it cool down a bit along the way.

Running the Actual Half Marathon

I had created a half marathon “workout” on my Garmin watch. It was just two steps – a) run 13.1 miles, b) cool down. I figured this would count down for me nicely, and I could jog a few extra meters on the cool down to make sure the full race registered as a half marathon.

I took my place at the street corner, pressed the watch button, and set off. After the first two hundred meters or so, I looked at my watch and noticed my pace was way too fast. I tried to reign it in a bit, and by the time I hit the first 800m it had averaged out to an 8:25 pace.

Faster than I planned, but I felt good. I eased up a little bit, and came in at 8:38 for the next half. Even though this was faster than I planned to start, it felt so effortless that I thought I should just stick it out. Over the next few miles I actually sped up slightly – to about 8:20/mile.

But then, around mile 6, it didn’t feel so easy. I was slipping. First, I had a half mile split at 8:46. Not bad, I thought. I can still bring this home. But the next one was 9:07. Uh oh.

I picked up the pace after that, but it wouldn’t last. The next three half miles were under 9 minutes, but then I hit another split at 9:09. And 9:39. And 9:50.

For the last four miles I see-sawed a bit, getting slower and then slightly faster. But overall, I was getting much slower. Miles 7-9 felt hard, and miles 10-13 my legs just felt heavy and dead.

My last full mile was over 10 minutes, and that was aided by a nice long, gentle downhill.

I managed to pick up the pace ever so slightly and kick a little for the last tenth of a mile. When I hit the 13.1 mile mark, I tried to keep jogging for a bit. But I only made it maybe 10 or 15 steps before I hit the button to end the cooldown, and I called it a wrap.

Final time: 1:57:38.

Chart of my half marathon pace, from my Garmin activity. You can it start to falter around mile six and then steadily decline around mile 8.

Lessons Learned from My Half Marathon Time Trial

So obviously, things didn’t quite go according to plan.

I did make my first goal – to beat two hours. But I failed at the achievable goal of beating my 1:54 PR, and I didn’t even come close to running my “potential” of 1:52.

So what happened? Let me reflect a bit on where I think things went wrong.

Biggest Half Marathon Mistake – Going Out Too Fast

No doubt about it, I think the biggest problem here and my biggest mistake was going out too fast.

I had planned to run 8:45/mile or slower in the beginning. I thought it out in advance, and I knew it was a good plan.

But when I got warmed up, I felt good, and I let my body lie to me. I thought – if I can run 8:30/mi or 8:20/mi this easily, I can keep doing it for the full 13 miles… right?

Wrong. There’s a thin line – your lactate threshold pace – between a sustainable pace and an unsustainable one. I knew that my threshold pace was probably about 8:20 to 8:30, and logically that meant I couldn’t hold that pace for more than an hour. In the moment, I thought maybe I was more fit than I thought – that all my training had somehow paid off – and it turns out I wasn’t.

Predictably – in hind sight – I held that pace for close to an hour and then started to struggle. By the time I was halfway through the race, it was too late. I could only struggle through to the end. But I’m sure if I had started out more conservatively, I could have finished much stronger.

In the end, my average pace was 8:59/mi. Even if I had started at 9:00/mi for the first three miles and then sped up, I would have been better off in the end.

Running a Half Marathon Alone is Tough

There’s no doubt about it that I was wiped out in the second half. But besides the physical exhaustion, there was also a mental exhaustion.

Five laps of a small course gets repetitive. I didn’t hardly see anyone along the way, and I definitely wasn’t running with anyone. It’s just hard to run a race this long by yourself.

I had already done a 5k and a 10k time trial, and it was easier to push myself through to the end. In the second half of the half marathon, I found myself lagging a bit, then speeding up, then lagging again.

If I had some other runners there to try and keep up with, or if there was a crowd cheering me on, I might have been able to eke out a little bit of a faster finish. I don’t think this would have completely saved the second half of my race, but it could have possibly made a small difference in the final result.

Should I Have Brought Food and Water?

I’m still not sure about this one. But I’ve spent a while mulling it over.

On the one hand, 13 miles is a long way to run without water. But I’ve done runs of similar duration (~2 hours) in training without water. Some of these were on my warmer mornings. I’ve finished a couple runs feeling dehydrated, but I didn’t feel that way at all at the end of this race.

In discussing my performance, someone suggested to me that I might have bonked and run out of energy. I suppose it’s possible. But the science says your body should have enough glycogen stored up to run for close to two hours before that happens.

Two weeks prior, I did a 12 mile long run and I finished the last five miles below 9 minutes per mile. I didn’t even eat breakfast that morning.

Given the fact that I’d loaded up on carbs leading up to the race, I ate breakfast the day of the race, and I regularly trained fasted, I just don’t think food was the problem. If I stalled out later in the race – like mile 11 or 12 – that might make sense. But my problems were apparent less than an hour into the race, well before my body should have been out of fuel.

So What’s Next?

At the end of the day, I’m happy I finished. No, I didn’t quite hit my goal time, but now I’ve got a baseline and I know what I’m capable of.

Long term, my plan is to prepare for a full marathon next fall. I’ll probably do a more robust half marathon training plan and another race or time trial in the spring.

In the meantime, I’m going to spend a couple of weeks recovering. Then I’m going to embark on a 5k training plan for the winter and spend a little time in the weight room.

And next time, I won’t go out too fast.

Lessons from a Half Marathon Time Trial: Don’t Go Out Too Fast

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