1. Lean muscle mass. This would happen pretty naturally for anyone carrying an extra 25-40 pounds everywhere they went for months. Everything you do is harder. Then baby comes and rapid total weight loss happens before the corresponding muscle loss. Voila… super human strength.
2. Deprived muscles. I hate it when people say being pregnant is just like wearing a weighted backpack. I hiked tons with my 30 pound toddler strapped to me and can say for sure that it’s not. Especially late in pregnancy, your phasic (mover) muscles are in shorter supply of oxygen and glucose. The burn comes quick. But once you have the baby, your tissues (and particularly the phasic ones) see an instant reversal in insulin resistance and there is more available oxygen. Foreseeably, they’ve become better at working with less so they’ll be far more efficient with more.
3. Hormones. Pregnant and postnatal ladies are full of them. It’s likely that progesterone, estrogen, and testosterone make women stronger and more powerful postpartum. Although best known for its ability to cause grave injuries, relaxin (which has a global “relaxing” affect on soft tissues) could actually help to naturally increase range of motion.
4. Motivation. New moms are infamous for driving their coaches nuts. They’ve been sidelined for months and they’re chomping at the bit to get back into action. At the same time though, they now know that competing isn’t everything so the pressure is off.
5. Mental toughness. How many athletes would call it in after a sleepless night? How about a week of sleepless nights? How about a month? New mom athletes can’t. And they only have an hour to do their 58-minute workout, one babysitter and one chance. So they’re getting it done.