Running a Half Marathon During My Third Trimester

It seemed like a great idea back in May. “I’m SarahFit, training for a half marathon will be a fun experience to blog about while pregnant,” I convinced myself. I accepted the challenge of running the Nike Women’s Half Marathon in San Francisco at 29 weeks pregnant ( also the 7th month and 3 trimester of pregnancy) with ClassPass.

Truth be told, up until about a week or two ago, I did feel great running. Sure I’ve told you about having to pee but other than that, I’ve felt pretty great. Now with less than a week to go I’ve lost my motivation. My schedule has been crazy, I was feeling really stressed about getting everything done and I missed my Race Pace Trainer Jess. Nike set up the ClassPass runners with one of their guys and I just never fully trusted my workouts like I trusted the ones Jess gave me.

I had to add in two rest days because running back to back days became too difficult. I enjoyed doing yoga on my own with my prenatal DVD or using the foam roller. I multi-tasked on Saturday making cookies while stretching.

Foam Roller

My joints started to ache after each run around 25 weeks. A 5 mile run felt like 8 or 10 on my lower body. When my plan told me to run 10, I ran 8 two weeks ago. When it said 8 on Friday, I ran 6. I NEVER did this for Boston or Chicago Marathon training. I would try to fit in my runs when I had the most energy and if I woke up late and couldn’t fit in all the miles, so be it.


The “easy runs” in my training schedule had to be reduced to walks or otherwise my body was too tired the next day to put in a good effort.The picture above is from my walk on Sunday. You can really see the bump when I turn side ways!

My favorite training days were when I got to go spinning or go to BTone and do Pilates. I wish that my Nike trainer had incorporated more of those days since this challenge is technically sponsored by ClassPass. After the race, I can’t wait to just do those types of workouts that are easier on my joints! Jess was always great at adding these things into my marathon plans because she knew I loved classes.

BTone Pilates Pregnant

That being said, my plan has always been to just finish the half marathon. I’m going to walk up the hills and take breaks if my heart rate goes above 170 bpm. I try to keep it below 160 but I still feel like I’m at a 7 RPE when it gets around 165. It’s hard for me to talk when I get above that which is my own signal for “Slow the F* Down.”

Today I ran the Tuft’s Health Plan 10K For Women. It was allowed my training plan less than a week before my race because my pace is so slow these days.

Tufts 10K Recap

My goal was to take it easy but I couldn’t walk. I’m too competitive. It was hard for me to line up with the 10 minute mile pace group. I knew that was going to be my pace but having run 26.2 miles just 6 months ago at a 9 minute mile pace, it hurts the ego a little bit.

Just as planned, I was able to maintain my 10 minute mile pace. It was unseasonably hot out though! I stopped at each water stop and walked the length of the tables drinking a cup each time.


With about 2 miles to go, I stopped to use a port-a-potty along the course. At about mile 5, my body started to be like, “Why are we doing this? Can we walk now?” My hips just felt sore and uncomfortable. I wanted to walk but with less than a mile to go and my heart rate in check, I changed up my stride to be less bouncy and finished strong with a time of 1:03:22 (but if you subtract a minute for peeing, my watch said 1:02:29 – I’m quick in those filthy things.) IMG_0443

The race wasn’t exactly the confidence booster I thought it might be. I’m confident I’ll finish my half marathon but I’m also thinking I’ve got to figure out a good run/walk plan so that I do not break at mile 6. After the race, my legs hips were a mess.

I had a sandwich, some chips, some yogurt and a large chocolate chip cookie. I also drank plenty of water. I took a Hubway bike home which was much easier than walking on my joints. It was nearly impossible to put weight on one leg to take off my leggings prior to getting in the shower.

My flight leaves for LA tomorrow at 11am. I’ll be working on the SFit digital gym Wednesday and Thursday and then flying up to San Francisco to meet up with the rest of my ClassPass team for a jam packed race weekend.

After Sunday, I’m really looking forward to NOT running more than 5 miles.

Did you run during pregnancy?

I’m glad I’ve kept it up thus far, but I’m ready to take things down a notch.


Running a Half Marathon During My Third Trimester

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  • Lauren

    Thanks again for giving me the opportunity to run! I had a great race, considering how hot it was and how little I trained. It’s been a busy fall!

  • Paula

    You should be damn proud of yourself for taking on this feat! I ran throughout my pregnancy, and managed to be lucky that I didn’t experience any aches or pulling. I didn’t do any races and definitely couldn’t run back to back days, and also never ran more than 4 miles during my last few weeks. I actually ran 4 miles the morning my doctor told me he was inducing me (only at 38 weeks)

  • linda

    Awesome job, keep doing your best and forget the rest. Hope the weekend run goes well. I ran right up to delivery with all 7 babies and now i get the pleasure of running with my teenagers, they push me!. It is all worth it.

  • Louise

    You’re an inspiration Sarah! So impressed you’re doing this when you’re preggers. A lot of debate around pregnant women and exercise in Australia at the moment, so good to see you showing us how it is done ?

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