I can't tell you how many clients I've had who, the moment they get confirmed pregnancy news, assume their entire strength training program has to dramatically change. Worse yet, I can't tell you how many of them have physicians that emphasise this, even to the extent of telling first-trimester pregnant woman not to exercise at all.
[I want to preclude this entire discussion, by the way, by noting that I am referring to apparently healthy, non-high-risk pregnant women - although even "high-risk" pregnant women (I was one of them, because of my "geriatric" age during pregnancy!) can perform safe exercise, but that's a discussion for another blog.]
With my second pregnancy, I didn't want to "bother" my very busy OB-GYN with early-trimester confirmation scans, so I just went to a local women's clinic doc. Upon walking in, the (older, male) doctor said, "Wow! You look very fit!" and I said, "Thanks, I'm actually a trainer." He immediately followed up with, "...but you're not doing that stuff now, right?"
I was a healthy and normal nine weeks pregnant with a second baby. Of course I was doing my "stuff" (insert eye roll here).
Point is, prenatal fitness is an area of great contention between the "general" (and I use that term to mean conventional, and perhaps a little old-school) medical community and the fitness community. Even within the fitness community, a lot of trainers won't (comfortably) address a pregnant client, and when they do, they tend to underestimate what she is capable of, have less clarity on what movements will benefit her the most, and coddle her a bit too much (full disclosure: this even applies to myself as a prenatal trainer prior to actually having my kids!).
So what are the "new rules," and how can you approach your own prenatal fitness journey?
The American College on Obstetrics and Gynaecology is the authoritative source for baseline recommendations, so I'll start there. They say:
"If you are healthy and your pregnancy is normal, it is safe to continue or start regular physical activity. Physical activity does not increase your risk of miscarriage, low birth weight, or early delivery. Ideally, pregnant women should get at least 150 minutes of moderate-intensity aerobic activity every week. If you were very active before pregnancy, you can keep doing the same workouts with your ob-gyn’s approval. But if you start to lose weight, you may need to increase the number of calories that you eat."
A couple points of note here: 150 minutes is 30 minutes, 5 days per week - a great start for ANY pregnant woman, active or not (think walking, swimming, or prenatal yoga if you're an unsupervised beginner exerciser). "Very active" women (like me!) don't need to really change much until physiology demands it (aka, if you drop core workouts the moment you get preggo you will very much regret it). And if you're exercising SO much that you actually start losing weight (!) - I would definitely take a strong look at that volume, as your coach.
Now about that pesky myth about "maxing out" at a heart rate of 140 bpm?
This recommendation was established by ACOG in 1985, quickly revised in 1994 (nearly THIRTY YEARS AGO, ladies!), and the most recent studies on the issue suggest that there is no additional risk to the fetus with vigorous exercise. The most recent studies even suggest that unless third-trimester (read: HEAVILY) pregnant women are going to 90%+ of maximum heart rate, vigorous exercise is safe for healthy pregnancies (here's another one that looks specifically at fetal outcomes, just so ya know).
Final point, because this wouldn't be a Coach Amanda Lim publication unless I was harping on the paramount importance of strength and resistance training (ha) - there are definitely some exercises that are better than others during pregnancy. When putting together my 40-week LIFTING MAMAS prenatal workout program, I focused on movements that support the center-of-gravity shift that occurs during pregnancy (strengthening deep core TVA and lower back), prepare the upper body for the postural challenges of breastfeeding/pumping (strengthening upper and mid-back and rear shoulders), and promote balance, mobility and stability in standing positions (squats, supported lunges, plank variations). These skills are crucial for adapting even the fittest bodies to the demands of pregnancy, and preparing us for a strong, resilient postpartum recovery.
Pregnancy is a beautiful season, but it can (dare I say should?) be a strong and active one, too. Comment or reach out if you're looking for evidence-based guidance to support your journey - I'd love to help.