My Latest Half Marathon Time Trial and a Feeling of Deja Vu

A man in the distance running a half marathon time trial.

Two weeks ago, I ran my latest half marathon time trial. I was in much better shape than I was last year, and I expected to both improve my time and run a better race. Unfortunately, while my time did improve significantly I still blew up in the second half of the race – similar to what happened to me when I ran a time trial last October.

But in this case, I don’t think it was just a bad pacing decision. After some reflection, I’m pretty sure my issues stemmed from the timing of my Covid vaccine. I had gotten my second shot earlier in the week, and in retrospect there were some clear impacts on my running performance. But that’s a topic for another post.

For today, let’s just focus on the taper, the time trial, and the recovery.

Tapering Leading Up to the Half Marathon Time Trial

Coming to the end of my half marathon training block, I was feeling pretty good. I had my last real workout (2 x 3 miles at threshold pace) ten days out.

After that, it was time to ease up a bit on the volume and hopefully feel well rested for the time trial.

My peak mileage had been around 46 (46.5, 45.25, 44.25, 46.25 in the final four weeks).

The week of my final workout, I started to bring that down. I only had one long workout instead of the usual two, and I dropped by long run down to an easy ten miles. I kept the long run easy throughout, and I just sped up near the end for a quick mile around half marathon pace. My total mileage for the week was 37.75.

The week of the time trial, I had no real workouts. Monday was my usual off day, and then I had short runs (3-5 miles) from Tuesday to Saturday. Thursday, I included two miles at race pace and the day before I did some strides. I put in a little under 20 miles in the days leading up to the race, and including the race and warm-up I ran 34 miles for the week.

I seemed to be feeling good. I was able to run short bouts at race pace fairly easily, but after the final workout I didn’t spend any considerable amount of time at race pace. So I guess in retrospect it’s hard to know in 1-2 miles whether a pace is sustainable for a half marathon or not.

Prepping and Warming Up for the Half Marathon Time Trial

Leading up to the day of the time trial, I was fretting a bit about the weather.

It was supposed to be rainy Sunday morning, and I considered either running it a day early or doing it early in the next week (Monday or Tuesday).

I ended up sticking with Sunday, and it worked out perfectly. There was some light rain in the morning, and by the time I left (a little before 10am) it was nothing but a mist. It had all but stopped when it was time to run the actual time trial, and as an added benefit there were very few people out at the reservoir.

That was something I had only considered in the weeks leading up to the time trial. Throughout the winter, the walking path around the reservoir was pretty sparse. But as spring sprung and the weather warmed up, each weekend seemed more and more packed. If it was a beautiful Sunday morning, I might not have been able to run a race with all of the dodging I’d have to do. But the weather helped me out here. When I started, there was almost no one else there, and it only got marginally busier throughout the morning.

Before I left for, I went through my usual routine. I had a cup of coffee, drank some water, and hit the bathroom. I’d eaten plenty over the past few days, so I wasn’t too worried about carbs. I gobbled up a few handfuls of raisins on my way out the door, just to top things off.

For a warm up, I jogged a mile over to the reservoir. I made a quick bathroom stop when I got there, and then I ran a few strides. I was feeling loose, and finished things off with about a quarter mile at race pace.

At that point, I stopped my warm-up run on my watch and took my place at the imaginary starting line. It was time.

Running the Time Trial

My pacing plan was start out at what I considered to be a conservative pace – around 7:45 – 7:50/mi – for the first few miles. From there, I could slowly shave some time off over the middle of the race and really push it in the last few miles.

Unfortunately, that plan didn’t really pan out.

I started out fine. The first half mile was a tad fast (7:30/mi pace), but after that I eased into my target. The next two and a half miles were more or less 7:45 +/- 5 seconds. So coming into the three mile mark, my average pace was a little under 7:45/mi and I thought everything was going according to plan.

After three miles, I planned to pick up the pace slightly – shading down from 7:45/mi to 7:40 or 7:35/mi. Based on my recent workouts and my 10k time trial, this should have been perfectly do-able. And for the first half mile, it was. I ran that split at 7:34/mi pace, but after that I fell off. The next split was very slow (7:57/mi), and it felt too hard to bring it back down to 7:35/mi. Instead, I tried to recover and stick with the original conservative pace.

The next couple of miles were ok, albeit a little harder than anticipated, but I was still running +/- 7:45/mi.

My plan was to start off conservatively and pick up the pace. Instead, I started to struggle after six or seven miles and my pace slipped further and further.

My watch clicked at the 6 mile mark, and I had planned on picking up the pace if things felt good. They didn’t, so I just tried to hold on. I figured I had come this far around 7:45/mi, and if I could just hold on to that I’d be fine. I wouldn’t make my stretch goal (1:42 or 1:43), but I should be able to easily beat my main goal (1:45).

Mile 7 wasn’t great, but it wasn’t too horrible. I felt myself slipping a bit, but I maintained a ~7:50/mi pace. From there, it slowly but inevitably rolling down hill.

At mile 8, I hit my last split under 8:00/mi (7:57/mi). From there, the time just kept ticking up slowly – 8:23, 8:26, 8:42, 8:30. Every time I tried to push it a little bit to recover, I’d make it a few hundred meters before I felt the pace slipping again. I had hoped to keep the pace on the second half under 8:15/mi, so I could at least finish under 1:45. But that wasn’t meant to be.

My pace gradually slipped from the low 8:00’s to the high 8:00’s, and there were a few splits above 9:00/mi.

My watch marked the finish of 13.1 miles at 1:47:10. A disappointing 2 full minutes over my “easy” goal.

So What Went Wrong?

I knew I was in better shape than this, and I was disappointed with my finish. Although I was happy that I smashed my old PR from when I was 30, as well as the baseline time trial I ran 6 months ago. I might not have run the best race I could run, but at 37 I’m definitely in the best shape of my life – and hopefully getting even better.

After I got home, showered, and poured some coffee, I looked at the data to see if there was some hint at what went wrong.

Right away, the heart rate data stood out as problematic. In the first half mile, my heart rate was still warming up. But from there, it had settled in around 161-162 bpm. For me, at this effort, that was too high. Then, about halfway through the race, as my pace got slower and slower my heart rate dropped as well.

My heart rate started off too high – at an average of 161-162 bpm – and as I struggled to maintain to my pace my heart rate dropped as well.

A good reference point is the 10k time trial I had run a little over two weeks prior. There, my heart fluctuated between 161-162 for most of the run. In the second half of the race, it rose to around 163 and it was 164-165 in the closing mile. But this was at a significantly faster pace – the first three miles averaged around 7:35/mi and the overall pace was 7:26/mi.

Another good reference point was the last workout I had done. I ran 2 x 3 miles, with a target pace of about 7:40/mi. The first interval I ran 7:39/mi with an average heart rate of 158. The second interval was 7:40/mi and an average heart rate of 157. This is consistent with my heart rate over similar workouts with long intervals or tempos run at half marathon pace.

The weather for all three of these runs was similar (below 60 degrees, cloudy), so there was no weather related reason for my heart rate to be higher. Yet at the beginning of the half marathon time trial my heart rate was at a level consistent with a 10k pace (~161-162bpm) – while my pace was just barely at half marathon effort.

The only explanation I can think of is that this was a lingering effect of the Covid vaccine. I’d received the second Moderna vaccine shot earlier in the week. I’d suffered some mild side effects that evening and the next morning, but I was feeling better as the week went on. However, in retrospect I don’t think I was back to 100%. I’ll write another post just focusing on the impact of the vaccine – looking back and reflecting on my performance in the week following both my first and second shot – but I wish I had waited an extra week before running the time trial.

Recovering and Looking Forward

Well, the bad news is that I didn’t hit my goal in the half marathon time trial. But the good news is that my recovery has been going very well, and I still think I’ll be in a great place for marathon training this summer and my first marathon in the fall.

I took first week after the time trial easy. Monday was my regular off day, although I did go for a short hike with my dog. Then I got back into my regular running routine, Tuesday through Sunday, albeit with lower mileage and an easy pace. Throughout the week, I stuck with shorter runs of 3-4 miles on the trails, and I did a few sets of easy strides later in the week. On Sunday, I allowed myself to go for a “long” run of a little over 8 miles. This felt good, and I picked up the pace over the last mile to wake my legs up. My overall mileage was 25.75 – the lowest total since my recovery week following my last half marathon.

This week, I inched a little closer to normalcy. I stuck with the trails for the most part, and most of my runs were still 3-4 miles. But I did extend my Wednesday run to 6.5 miles, and today (Saturday) I ran about 5 miles around the reservoir to see what an easy pace felt like on the road. After I got warmed up, I was ticking off miles below 9:00/mi, and I felt good. I’m looking forward to a legit long run tomorrow (12 miles), and I think I’m more or less fully recovered.

This week, I’ll have run 34 miles. Over the next four weeks, I’m going to stick with mostly easy running and bump up my peak mileage a bit. The progression I have penciled in is 42, 46, 52, and 53 miles per week. The following week, I’ll drop back to 45 mpw – and that Sunday will mark the first official training run of my marathon training block. I’ll be following Jack Daniels 2Q training program (from Jack Daniels Running Formula), but more on that as we get closer.

Over those four weeks, I don’t plan on doing any real workouts. I’ll keep the pace easy, and I’ll run mostly on the trails. My two longer runs (Wednesday and Sunday) will likely be on roads to simulate what I’ll be doing during my marathon training. I also plan to incorporate a few days of hill sprints towards the end. I’ll probably also run a couple shorter time trials to get a new baseline on my speed – I’m thinking a mile, and either a 800m or 1k.

All in all, although I’m disappointed with the results of the time trial, things are still looking up. I feel a lot stronger for having finished the half marathon training block, and I’m feeling good and ready to bump up my mileage, and if I can stay consistent over the summer I have no doubt that I’ll run a great first marathon in October.

My Latest Half Marathon Time Trial and a Feeling of Deja Vu

One thought on “My Latest Half Marathon Time Trial and a Feeling of Deja Vu

  1. Hi Brian, thanks for the race report! I enjoyed reading it. Well done on the new HM PR! It’s worth celebrating even though you didn’t make your target.

    I think your COVID vaccine analysis is spot on. Interesting how your heart rate dropped off in the last half of the run!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to top