Here I’m answering how I maintained milk supply while training for a marathon and in general keeping milk supply with heavy exercise.
Recently I ran the Rock ‘n Roll Marathon in Savannah, Georgia, at 7 months (+3 weeks!) postpartum while exclusively breastfeeding. I’ve gotten a lot of questions about maintaining milk supply while exercising 5-6 days a week so today I’m answering them all.
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How I Trained for a Marathon While Breastfeeding
Let me lead with: Breastfeeding has been extremely important to me. I’ve had every intention of nursing at least a full year if I’m physically able, despite challenges on the outset. To me, the goal of a postpartum marathon couldn’t get in the way of nursing and vice versa. They needed to be friends!
Managing Cardio and Maintaining Milk Supply
Research here and here (and suggested here) noted exercise of 45 minutes per day 4-5 days a week did not decrease milk supply or negatively impact infant growth. Though anecdotally, a lot of moms talk about reduced milk supply when they reintroduce heavy cardio after baby.
Because I’m a work-from-home mom and primarily nurse, it’s not as easy for me to notice dips. That said, I ramped up my mileage about the same time I stopped being engorged (~4 months) and had periods of time I was concerned about not having enough milk. We also introduced solids at 5 months per her pediatrician’s recommendation, which can negatively impact milk supply.
Pumping to Boost Milk Production
Milk supply is primarily determined by demand. Pumping makes your body think the baby needs more milk, thus increasing milk supply. You might not get much milk at first when you add in an extra session, but your body should start adjusting in a few days.
Any time I thought my supply might be dipping, I just added in an extra pumping session a day. For me, I found the best time to be about 10 pm, in between her before-bed feeding and middle of the night feeding. Every body is different and some people find supply for pumping is best in the mornings or in the middle of the night. It’s up to you when to add in your extra session (also keep in mind maintaining your SANITY!).
Limiting Days of Endurance Training
Another thing I did was limited long-distance running to only 3 days per week. Tuesday and Thursdays were shorter 3-6 mile runs (sometimes 8), and Saturdays were my long-run days (6 to 18 miles). I always take Sundays off. The other three days of the week I did a 5 minute cardio warm-up and then only lifted. Occasionally I did a more intense exercise class on one of my lifting days.
Could I have done long distance more and kept milk up? Maybe. But my knees are bad, training was five and 1/2 months long and it was the most sustainable plan for me. I did have some weeks where I ran 3-4 miles 4 or more times in a week and didn’t see a dip.
In my opinion, minimizing days of the week I did heavy endurance cardio and adding in extra pumping sessions were extremely helpful to maintain milk supply.
Notably, now that I’m not training long-distance post-marathon and instead doing more plyometrics, lifting and high-intensity interval training (high intensity, short periods of time), I haven’t had any milk supply concerns or needed to pump extra.
Extra Calories & Fluids to Maintain Milk Supply
What might be most critical for maintaining milk supply with heavy exercise is eating enough calories and drinking enough fluids.
Your Body Needs Extra Calories for Training and Milk Supply
I don’t regularly track exactly how many calories I eat, but if I had to guess I was probably eating about 2200+ calories a day (and yes I have still been able to lose about 46 of the 51 pounds I gained during pregnancy). To increase my calories I ate spoonfuls of peanut butter and increased my portion sizes. What used to be one taco became two tacos and I pretty regularly out-ate my husband at meals.
Most importantly, I listened to my body and ate more when I felt hungry. Increasing calories was not a “free-for-all” or an attempt to overeat, just a response to actual hunger cues. Your body needs the calories for fuel for all of your training and to keep a small human alive. Listen when it’s trying to tell you something.
Actual calorie needs for lactation are an extra 330 calories per day from birth through 6 months, and an extra 400 calories per day for months 7 through 12 (reference here).
Increased Fluids for Nursing and Exercise
You need enough fluids every day to cover:
- your body’s needs,
- the fluids needed for your baby to drink,
- your sweat loss from exercise (this will be higher when it’s hot outside).
I planned my runs around a long trail that had water fountains nearly all along the way. On stroller-run days, I brought a water bottle with me and non-stroller days I just used the water on the trail. At home I keep an ice-water-filled Yeti to remind me to drink. I find if it’s not ready and in my sight, I completely slack on hydration.
Breastfeeding Logistics on Long Runs and Race Day
Usually I didn’t bring Baby T on any runs over 8 miles. I nursed before leaving the house for long runs. If she didn’t eat well enough or wouldn’t wake up (I had to leave early ~5:30 some mornings), I pumped so I was empty for the run.
Race Day Breastfeeding
On race day, I tried to feed her before leaving for the race but she was too tired from traveling the day before. I brought a hand pump in case I needed it during the race, but I hadn’t used it before and it’s not as efficient as an electric. I was stressed trying to leave quickly for the race and hardly got any milk out (I should have practiced with it first). Baby T woke up shortly after we left for the starting line, so my husband rushed her over to me and I nursed her before the race. I didn’t need to nurse or pump during the race, and then I nursed her again at the finish line. I think bringing a hand pump in the support car is a good idea, I just would recommend practicing with it beforehand!
I wore a sports bra that unsnapped in the back and a loose tank so I would have easy access if needed. I made sure to pack a nursing cover (here’s another one I have) in the diaper bag for my husband!