Modern motherhood is rewriting the rules—and mums like Sophie Power, who breastfed her 3-month-old son mid-ultramarathon during the brutal 105-mile Ultra-Trail du Mont Blanc, are proof that strength and nurturing can absolutely coexist.
But one question I hear from new mothers almost every week is:
“Can I still breastfeed if I start running or exercising?”
The short answer?
Yes. 100% yes.
And not only can you—moving your body might just make you an even stronger, calmer, happier mother.
Let’s explore how your breast milk adapts when you move, why your baby still thrives, and how I guide mothers through this journey every day at Sleeping Little Angels.
The Science: What Happens to Breast Milk During Exercise
Your body is extraordinary—and so is your milk. Far from being “ruined” by exercise, it simply adapts. Research shows:
Lactic Acid: A Temporary Guest
- Only very intense exercise (think 100% of your VO₂ max—the kind of effort most of us never reach) causes a small rise in lactic acid in breast milk.
- This slight change might mildly alter taste for up to 90 minutes—but it does not harm your baby and does not reduce nutrition.
- Moderate exercise (50–75% VO₂ max) does not increase lactic acid at all.
Translation: If you can still talk while jogging, your milk’s lactic acid stays stable.
Immune and Hormonal Shifts: Tiny and Temporary
- After intense workouts, immunoglobulin A (IgA) may dip slightly for about 10–30 minutes, then return to baseline within an hour.
- Exercise may even boost adiponectin, a hormone linked to healthy metabolism, in breast milk shortly after training.
- No significant changes occur in pH, fat, protein, lactose, or long-chain fatty acids—these major nutritional pillars remain unchanged.
Safety for Your Baby: Proven by Decades of Research
Here’s the most important part: babies do just as well when Mum exercises.
- Infants accept milk normally even after high-intensity training.
- Growth, weight gain, and development are unchanged.
- Milk volume and overall composition remain steady.
And guess what? Over 84% of competitive runners keep running while breastfeeding—proving it’s not just possible; it’s normal.
Beata’s Golden Guidelines for Breastfeeding Runners
At Sleeping Little Angels, I coach postpartum women to combine nurture and movement without stress. Here are my essential steps:
1. Feed or Pump Before You Train
Empty breasts = more comfort + easier motion.
(Bonus tip: Don’t dump that milk—it’s still liquid gold.)
2. Invest in a Supportive Bra
Your body is changing. A flexible, supportive sports bra makes every mile more comfortable.
3. Fuel for Two
Breastfeeding burns ~500 kcal/day. Add exercise, and your body needs even more nourishment. Prioritize nutrient-dense meals and hydration.
4. Supplement Wisely
Talk with your provider about supporting minerals, antioxidants, and micronutrients—they support both milk quality and your recovery.
Why Movement Matters for Mothers
This isn’t just about muscles—it’s about mental health, hormones, and joy.
- Exercise releases serotonin, dopamine, and BDNF, the “feel-good” molecules that fight postpartum depression and boost mood.
- It improves cardiovascular and immune function.
- And most importantly—it reminds you that you are more than a milk machine. You are a whole, vibrant woman.
We need to normalize mothers putting on their running shoes without feeling guilty—because suggesting that women should “pump and dump” after a jog is misguided.
That’s not science.
That’s a meme. 🙃
Looking to connect with our local Tampa Bay moms? Checkout our friends at FIT4MOM Tampa Bay!
From My Heart to Yours
As a doula, I guide mothers through every step of the postpartum journey—from lactation support and nutrition coaching to safe exercise planning and emotional recovery.
You don’t have to choose between being an athlete and being a nurturing parent.
You can be both.
And your baby?
They’ll thrive right alongside you.
