Often we consider how our weight or what we’re eating might impact our fertility – either positively or negatively. But what about exercise?
As a runner, I’ve seen conversations like this play out on many runners forums:
“My doctor tells me to cut back on running as it’s impacting my chances of conception!”
Often followed by:
“Don’t listen, I run 50km a week and I’ve never had an issue getting pregnant!”
So, what does the science tell us? Can exercise impact our chances of conception? And how much exercise is considered ideal?
As with anything, if you want to find a study supporting your lifestyle, there will most probably be one out there.
However, if you really want to improve your chance of becoming pregnant, here is the general consensus from the scientific community.
Vigorous exercise is probably detrimental to fertility
Almost every study out there concludes that high levels of exercise (measured by frequency, length of exercise, and intensity) are problematic.
This is because vigorous aerobic exercise may impair your body’s production of progesterone and estrogen, two essential hormones for ovulation and pregnancy.
Too much aerobic exercise may also disrupt ovulation cycles. Your body may choose to ‘shut down’ the reproductive system to divert energy to other systems needed for vigorous exercise. Interestingly, the same problem does not seem to occur among overweight or obese women, suggesting fat mass can also play a role.
All that said, some large-scale studies have shown that vigorous exercise may be beneficial as long as the exercise sessions are 30 minutes or less.
My thoughts? Exercise in moderation. Aim to exercise for around 30 minutes three to four times per week.
A sedentary lifestyle is also detrimental to fertility
Sedentary lifestyles are closely associated with excess weight gain. Excess weight gain can cause the body to produce too much estrogen, reducing fertility. It can also cause an increase in insulin, which affects the entire hormone system.
More people are at risk of under-exercising than over-exercising. If this sounds like you, look for ways you can incorporate more movement into your weekly routine.
Different ‘rules’ apply to women with PCOS
Women with PCOS respond to exercise differently to women without PCOS. Studies suggest they need more vigorous exercise more frequently – around three to five moderate to high-intensity sessions per week seems to give the best outcome for conception, as well as decreasing the risk of type 2 diabetes.
Exercise also helps to regulate body weight and insulin response, which is key for women with PCOS.
Moderate exercise is the key
Moderate exercise has been associated with improved fertility. It may improve hormone levels and regulate weight.
That said, underweight women should consult a health professional for exercise recommendations – and most definitely be conservative with their exercise plan.
Exercise may help with IVF
A study of obese women undergoing IVF found regular exercise was associated with higher success rates (39% compared to 16% in sedentary women). Regular exercise was also associated with improved live birth rates (24.4% versus 7.4%).
Another study found moderate exercise combined with weight loss had a positive impact on obese women undergoing fertility treatment.
Could nutrients and weight be more important than exercise?
Maybe. The science suggests that exercise tends to be good for fertility when accompanied by a healthy weight and healthy nutrient intake.
Studies also show that women who are overweight will benefit more from exercise, even at high-intensity levels, than women who are normal weight or underweight.
Timing is key
A Norwegian study followed women with fertility issues who enjoyed high levels of physical activity. The study found that decreasing their exercise levels led to conception, and a follow-up study of the same women found they had three or more children on average.
This study suggests that intense exercise does not impact your fertility over the long-term; rather it’s what you do when you’re trying to conceive that’s important.
Summarising the science: Exercise is pretty crucial
Moderate, regular exercise, such as walking the dog, going for a jog, enjoying a bike ride or doing some resistance training is an excellent way to prepare your body for conception, pregnancy, and labour.
Here are some of my top tips for getting the right amount of exercise when you’re trying to conceive.
Tips for getting the right amount of exercise
Increase or decrease your physical activity to a ‘healthy’ level in the months leading up to conception or fertility treatment (see your doctor’s recommendations for the latter).
Aim to work out for no more than a total of four hours each week at a level where you can talk but not hold an in-depth conversation.
If your BMI is under 25, make sure you supplement your workouts with a post-workout snack. This doesn’t have to be huge – think a handful of nuts and raisins, a crumpet with avocado, peanut butter on whole grain toast, or half a protein shake.
Sometimes we get fixated on a workout needing to leave us ‘feeling it’. However, it’s perfectly fine when you’re trying to conceive to add in a few days of walking rather than a heavy gym workout. A simple 30-45 minute walk around the block before work, at lunchtime, or before bed is a nice ‘down day’.
New to exercise?
If you don’t currently exercise, here are a few ideas to get you started.
Get a walking group together at work. Encourage your colleagues to come for a walk with you at lunchtime or on a morning or afternoon break.
Fit in incidental exercise whenever you can. For example, park further from the entrance to the shops, walk to the local store instead of driving, and walk the kids to school.
Hire a stationary bike and pop it in front of the TV. Cycle at night while watching your favourite show.
Take ‘walking meetings’ or ‘walking phone calls’. I did this a lot when I worked in an office. If it was a walking meeting, we would record it on our phones instead of taking notes.
Get up 15 minutes earlier and take a 10-minute walk or buy a skipping rope and skip for 10 minutes. Lay your exercise clothes out the night before so you can hop straight into them in the morning. I’ve had clients sleep in their exercise clothes so they have no excuses!
- Get a workout buddy. If you don’t have any kids yet, your partner might be a good choice. If you’re trying for number 2 or more he or she might need to be watching the kids if you’re working out so drag your mum or best friend along. You could double up on a personal trainer, go for a beach or trail walk, or challenge each other to a circuit through the local park or gym. I’ve also had clients meet up with friends after work and swim laps at the local pools.
If you’d like more exercise tips and advice, book a free 15-minute consultation.