In so many ways, breastfeeding and exercise go hand in hand and are complementary for each other. One thing you should be aware of, especially if you’re a runner, is that your bone mineral density will decrease temporarily while you’re breastfeeding. The bone density decrease will actually be much more than what you’ll experience during menopause. Thankfully, after you finish breastfeeding and your period resumes, your bone mineral density will return to your baseline.1
Don’t let that deter you from exercising, though (and of course, the temporary decrease in bone density that you will very likely never even notice is only temporary, and the benefits of breastfeeding your little one are lifelong for them, so don’t let that in any way be considered an argument against breastfeeding). Research shows that a regular exercise program that includes resistance training, core strengthening, and cardiovascular exercise can slow the bone density loss, and this difference between exercising moms and non-exercising moms is significant (measured at 5 months postpartum).2
During the time that you are breastfeeding, you’ll need to progress your impact exercises carefully to help decrease the risk for stress fractures. In my book you’ll find an exercise program comprised of resistance training, core strengthening, and cardiovascular exercise that includes walking, running, and jogging stroller running progressions to help you keep a steady, healthy progression on track as you recover.