A pregnant athlete should expect to recover more slowly from her workouts.
Increased stem cell activity initiated by the fetus in its mother's body has a two-fold positive affect on the recovering pregnant athlete's body: 1. Faster recovery from injuries and 2. Increased rates of angiogenesis.
Something NFL athletes have known, and exploited, for quite some time is that increased stem cell activity reduces their recovery time from injuries and surgeries. In particular tendon injuries seem to see a healing burst as a result of increased stem cell activity. By better understanding the meaning and utility of exercise, one can also extrapolate the importance of a boost in stem cell activity in recovery from particularly strenuous exercise.
Bones and tissue in our bodies are constantly breaking down and replacing themselves. During exercise, bone and muscle tissue breaks down as an adaptation to the applied stimulus and is replaced by stronger material. The faster this process can occur, the faster the athlete can recover, the more stimuli can be stacked close to one another, the stronger the athlete can feasibly become.
By thinking about recovery from weight-bearing and endurance exercise as the need for tissue regeneration it is easy to understand why, when I was pregnant, it was near-impossible to become sore from a workout and I felt my recovery time had decreased. It is also good to note that one major aim of endurance training is to induce higher rates of angiogenesis, or endothelial cell proliferation and an increase in capillary blood vessels.
Enter fetal-maternal microchimerism (also known as fetomaternal microchimerism or FMc). According to Zhong and Weiner's 2007 study on pregnant mice:
Fetal stem cells appear to respond to maternal injury signals and may play a role in maternal tissue regeneration during pregnancy. Massive new blood vessels were formed around the injury site which indicated the incidence of high angiogenesis events during the recovery of the skin injury.
In an even more mind-boggling turn, the fetus continues to supply stem cell support to its mother even after it has departed from her body.
Fetal cells have also been identified in skin lesions of women with systemic sclerosis, a disease of unknown origin which often occurs in women after their child-bearing years.
This boost in FMc continues for quite some time according to Bianchi et al:
In humans, PAPCs (pregnancy associated proginator cells) have been described to persist in mothers almost three decades postpartum.
This means that recovery times decrease and the injury-assisting qualities of fetal stem cell activity increase in the maternal body even after pregnancy. Now that is some rad sci-fi shit I couldn't dream up if I tried.
If you're into doing research on this sort of thing, doctors, please do us ladies a favor and dig deeper on the topic than I was able to do in this article. You owe it to preggos everywhere. Those burly NFL players only wish they could be pregnant athletes.