I wish I were trying to be cute and leaving the “G” off Relaxing, but Relaxin is a hormone produced in increasing amounts during pregnancy. It’s a necessary hormone, but as an athlete, it’s not something you want in increased amounts. Relaxin is a protein-based hormone found in men and non-pregnant women. Pregnant women have ten times the amount as non-pregnant women.
Relaxin relaxes the blood vessels, ligaments, and tendons in your body. It begins its work in the beginning of pregnancy (before actually) by preventing contractions in the uterine wall and making implantation easier. It allows your blood vessels and arteries to expand to accommodate the extra blood volume. As you’re baby grows and shoves your internal organs into your ribcage you’ll be glad relaxin has made expansion of your abdominal muscles and ribcage possible. What you’ll be most happy about is relaxin ensures that your pelvis will be able to expand not only to accommodate your growing child, but to allow the child to be born.
Relaxed tendons are a problem if you are an athlete. It can be problematic if you’re not an athlete and you just want to go about your day without any pain or discomfort in your joints. Instability in your ankles, hips, and knees is something runners try to minimize and correct through strength training. When you’re pregnant, strength training isn’t going to help and you really, on some level, don’t want it to help because that baby has to exit somehow.
The instability can cause achiness and pain in your joints with just everyday activities, let alone running. Relaxed tendons and ligaments places you at higher risk of injury, even when doing exercises you have been doing for years pre-pregnancy.
What all of this means for pregnant runners is be careful and rethink increasing your miles or the intensity of your running workouts during your pregnancy, especially, during the first and third trimester when relaxin levels are at their highest. You’re also likely to feel increased soreness after runs, especially, in your pelvic girdle, hips, and lower back. Try using a maternity belt to help reduce the pressure of the baby on your pelvic joints.
You’ll likely have to decrease your miles and your pace as your son or daughter grow and their debut approaches. Reducing your miles to prevent injury, especially, an injury that could stop you from getting back to running after baby is born, is a small price to pay. Cross training with low impact exercises, such as swimming and cycling, will become your go to activities at the gym. I know this can be frustrating, but keep in mind it also means you’re closer to holding your little one in your arms.