Balancing fitness and pregnancy: training smarter through the first trimester

SUBSTACK • January 13, 2026

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I qualified as a pre and post natal personal trainer back in 2007 which feels like a lifetime ago now. Little did I know I would become pregnant 18 years later!

Pre and post natal is a beautiful area of health and fitness to work in because there’s often a shift in mindset. The focus is less about body composition and more about being fit and strong for pregnancy. Even after the baby/ babies are born, getting back into shape comes with a renewed sense of purpose and desire to be healthy and strong for our little ones - a role model for them to learn from.

It’s important to note that maintaining an athletic identity throughout pregnancy requires careful consideration and safety. There are some aspects of strength and fitness which require adapting.

Cardiovascular exercise

The goal is to be fit for pregnancy, not strive for personal bests, high intensity workouts or weight loss. To determine a sensible intensity, I listen to my body rather than focus on my Garmin heart rate whilst performing the activity. I love to run so I ask myself these questions:

With any form of cardiovascular exercise during pregnancy, we should be aiming for no more than 70% of our max effort. When I’m with my clients, I ask them “on a scale of 1 to 10 (10 being max effort), what level do you feel you’re working at?”. This is a far better indicator of intensity level than looking at heart rate. During pregnancy, heart rate isn’t a reliable indicator of effort during exercise as there are other considerations - our bodies are also working hard to grow babies!

Strength training

Keeping muscles strong through exercise helps to support joints as the hormone Relaxin increases leading to muscles being able to stretch more. Focus on body weight exercises, Pilates-based workouts and workouts using resistance bands and weights. Again, 70% max for all types of training, not just cardio. If you’re used to heavy lifting, it’s time to scale back a bit and listen to your body. Anything of a high intensity nature places stress on the body. While this is useful for strength and fitness gains outside of pregnancy, when our bodies are going through dramatic changes to support life within, we need to think about maintenance of strength not personal bests.

Focus areas - glutes. These need to be active and switched on so that they can support the changes that will come in the pelvis and in our posture. This also helps the lower back as our glutes are larger muscles capable of taking heavier loads whilst taking pressure off areas like the lower back. The core also needs to stay strong to help the central weight shift forwards but how we strengthen our core is different in pregnancy.

Although in the first trimester you can technically train your core with usual exercises, I decided to adapt the core component of my training plan from day one and stick to plank-based movements of all kinds I.e. renegade rows, side plank rotations, commando planks and slow mountain climbers. Essentially, avoiding all core exercises lying on my back. This is more important in the second and third trimesters but I think it’s a good habit to get into from the start.

I like the phrase “exhale and engage”. I remind my clients of this just before they start performing the hardest part of an exercise, like standing back up after a squat or pushing back up from a press up - to exhale and gently engage their deep core muscles by hugging their baby in towards the spine. By doing this with all exercises, they become core exercises too. You just have to remember to engage them and not relax those deep core muscles whilst performing the movement.

It’s never too soon to start pelvic floor exercises during pregnancy. It’s hard to teach and requires a bit of visualisation. I found this video easy to understand and the 3D images explain it well

. Once we can visualise the area to be worked, it’s much easier to perform the exercise and build up to the recommended amount per day.

Exercise should feel enjoyable. If you experience pain whilst performing any type of exercise - STOP. This is your body telling you that what you’re doing is not right for you at this moment. So forget the outdated mantra “no pain, no gain”. This was always flawed and responsible for many injuries. Just remember to listen to your body, to what feels right for you and go at your own pace. Rest is as important as staying active throughout pregnancy so be sure to schedule plenty of rest between activities and try to keep your stress levels low.