How Does the Covid Vaccine Impact Running Performance? Reflections on My Own Experience

I’ve seen this question pop up a lot recently in running groups – does the Covid vaccine have any impact on your running performance? And can you run after getting the vaccine?

Generally, the responses seem to fall into two categories. Some people have no symptoms at all, and there is seemingly no impact on their running. Others have minor symptoms that temporarily impact their running. But I haven’t seen a lot of people suggest that there are any long term effects – the same way that people have some seriously long term effects from Covid itself.

Now that I’ve received both doses of the Moderna vaccine, I wanted to reflect on my own experience and share what I’ve learned.

How Did the Vaccine Affect Me?

Before we talk about the impact of the vaccine on running performance, it probably makes sense to first talk about what impact the vaccine had on me in general.

I’ve written about how Garmin’s Body Battery works in the past, so I thought it would be useful to include graphs of that data here.

I received the first dose of the vaccine in late March, and I did not experience any severe side effects. That evening, my shoulder was a bit sore at the injection site. The soreness lasted a few days, and it slowly dissipated. I’ll be honest and say that the soreness was worse than I expected, but it was not “bad” by any stretch. Other than that, I had no significant symptoms. I didn’t have a fever or aches or anything of the sort.

The second dose was another story. I received the second dose about a month later in April. I had heard the horror stories about people getting their second dose, and my wife had some pretty bad side effects herself. Still, I was optimistic that it wouldn’t be too bad after my experience with the first shot.

I wasn’t so lucky. I was vaccinated around 11 AM, and I felt ok throughout the day. But late in the afternoon things slowly shifted. I took the dog for a quick walk, and there was a spike in my stress levels (see the graph above). That definitely wasn’t normal for a short walk.

By dinner time, I had some pretty significant body aches and I generally felt “sick.” The body aches turned into a headache, and that night I had trouble sleeping. I dozed off for a bit, but I woke up several times throughout the night and had trouble getting back to sleep. I never took my temperature, but I had some chills and I’m pretty sure I had a fever at one point.

The next morning, I tossed and turned in the bed for a while. When I “woke up” around 9am, I wasn’t feeling great but I was feeling a little better. I stayed in bed, drank some coffee, and tried to get some work done. I usually would run first thing in the morning, but I definitely wasn’t feeling up to it. Things got better throughout the day, and I was feeling more like myself by the late afternoon.

In terms of symptoms – and physiological responses as indicated by my Garmin Body Battery – things were more or less back to normal by nighttime. I slept well, and I woke up feeling great the next day.

But How Did This Impact My Running?

At first, I didn’t think there was much of an impact.

Both times I got vaccinated, I went for a run beforehand. I figured I would then be able to rest for the day and possible rest the next morning if I wasn’t feeling great.

After the first shot, I felt fine the next morning. I went for a run, and everything felt more or less normal.

I had a workout penciled in on my calendar (4 x 1.5 miles at LT pace). I was prepared to go for an easy run and do the workout the next day if I didn’t feel well, but I woke up feeling fine. I stuck with the workout as is, and I finished a full ten miles including the warm up and cool down. The rest of the week, I stuck with my pre-planned schedule.

After the second shot, I did not feel fine in the morning. I skipped my morning run, but I decided to re-assess in the evening. When I was done with work for the day, I was feeling a lot better and I went out for an easy run. But this time, despite my symptoms being mostly resolved, my run did not feel ok. I went for a very easy trail run (a little over three miles), and it did not feel easy at all. I was taking it easy the previous weekend as part of the taper for my half marathon, so I should have felt fresh. But it was a struggle to go just a few miles.

The next morning, things seemed about normal again. As part of my half marathon taper and prep, I had a short run planned with a couple miles at race pace. I did a two mile tempo run at race pace and felt more or less normal. I thought things were on the up and up.

Things Weren’t Looking So Good After All

I got my second vaccine shot on Tuesday, and I had a half marathon time trial planned for that Sunday. I thought this was plenty of time to recover, but in retrospect I was wrong. If you read my race report from the time trial, you know things didn’t turn out too well.

Long story short, I went out at my planned race pace. It felt ok in the beginning, but after a few miles I knew something was wrong. I had planned to start around 7:45/mi and speed up towards the end. My workouts in the weeks leading up to the time trial indicated this was very possible. Instead, after starting out at this conservative pace I struggled to try and speed up at all. About halfway through, I struggled to even maintain that pace. By the end, I’d slowed down to 8:45-9:00/mi. Try as I might to speed up, my legs were just dead.

When I looked at the heart rate data afterwards, I noticed something was amiss. Typically, my easy pace puts me in the range of 135-145 bpm. A marathon paced tempo should put me in the low to mid 150’s. A half marathon tempo would be 158-159bpm, while a 10k pace would put me a little over 160. I started out at a conservative pace that should have been easy enough for my heart rate to stay in the mid to high 150’s.

Instead, it quickly went over 160 and peaked around 162 to 163. My heart rate suggested I was racing a 10k, while I was running at half marathon pace. This coincides with the fact that I held this pace for a little over 10k – and then started to fall apart.

This got me thinking, and I looked back at the week after my first shot.

That next morning, I had run my interval workout as planned. My paces seemed ok. I slowed down a bit throughout the four intervals, but I thought it was because I had run the first one two fast (7:25/mi). My average pace for the four intervals was 7:35/mi – right on target – but each interval was a bit slower than the previous one. And my heart rate was through the roof. I averaged 166 for the first interval and 165 for the second. My Performance Condition, measured by my Garmin, also confirms that my heart rate was higher than expected given the pace.

By comparison, I ran 3 x 2 mile the next week. My pace was slightly slower (7:38/mi) to allow for the longer intervals, but the pacing was much more even. My heart rate was around 161 throughout the workout, and my Performance Condition was neutral. All in all, it was a better workout. And even that seemed a smidge high given the fact that I did a 10k time trial the following week, finished in 46:10 (7:26/mi), and averaged 162bpm. It’s also important to note that in all of these cases, the weather was similar – 40’s or 50’s – and so the weather shouldn’t have otherwise increased my heart rate.

There was also the issue of my long run that weekend. The Sunday after the first vaccine, I went out for what was supposed to be a 16 mile long run with 4 miles at marathon pace. I’d done this the week before without issue. But this week, I really struggled. When I tried to pick up the pace for the tempo segment, my pace was relatively slow and faded throughout the four miles. At the end of the tempo segment, I tried to struggle home. I didn’t make it. After 13 or 14 miles, I walked a bit. I tried again, I and gave up at 14.5 miles.

At the time, I chalked this up to a new route with more hills and to the fact that I was running in the afternoon instead of the morning. But now I’m thinking it had something to do with the lingering effects of the vaccine.

So What’s the Bottom Line – How Does the Vaccine Affect Running Performance?

Look. I am, as the saying goes, a study of “n = 1.”

I don’t know how you’ll experience the vaccine, whether or not you’ll have side effects, or if it will have an impact on your running.

But I thought it was interesting that there were noticeable impacts on my running after the first shot – despite the fact that I had no real side effects. I had assumed that since I wasn’t experiencing symptoms, my body was fine. In retrospect, that’s not quite true.

After some reflection, I’d say that the vaccine had some lingering effects on my performance for just under a week. In both cases, I got the shot on a Tuesday and I struggled on my Sunday run. The effects were more pronounced in longer, harder efforts. In a real, measureable way, it was “harder” for my body to move along at a given pace. My easy runs weren’t problematic, but my long runs definitely were.

So my advice: don’t plan to be in peak running shape for about a week or so after your vaccine. The good news is that I had some great workouts in between the two dates, so there clearly weren’t long term effects. But if I were you, I would definitely not plan any races for at least a week after you receive your shot, and I would probably steer clear of hard workouts.

Once your side effects – if any – have resolved you should be fine with easy running. But I’d consider it a recovery week and just do some easy running with some strides.

Hopefully you’ll learn from my example, and you won’t have to struggle through an ill-timed race or time trial.

And let me be clear. I would in no way discourage anyone from getting vaccinated. I’m glad I did, and I hope you do too. Just be mindful of the timing.