You won’t believe what goes on inside your pregnant body without you even realising!
If you are still feeling sick hopefully it will start to get better over the next couple of weeks. Chances are you haven’t noticed any drastic changes to your waistline yet, but you may have a bit of a bump, everyone is different. If you are an experienced exerciser make the most of the next couple of weeks before you have to start adapting your routine. If you are not an experienced exerciser then try and make active daily choices and do your daily exercisers (pelvic floor, bum and ab squeezes, see 3-Plan) and think about starting more regular, appropriate exercise once you have had the OK from your 12 week scan.
Try to remember how remarkable your body is. The journey to motherhood is incredible if you look at how your body changes and adapts to make its environment just right for your growing baby. This week we are going to look at what hormones are released in pregnancy and how they impact on exercise and the other changes that are going on inside your body that you should be aware of and reassured about in relation to safe exercising in pregnancy.
Let’s look at four of the big players: relaxin, oestrogen, progesterone and insulin.
The role of relaxin is to relax the ligaments of the pelvis to enable the joints to separate to accommodate your growing baby. Later, for your pelvis to open up and your baby to be born.
However clever relaxin may be, it is not able to target the relaxing effect on just the pelvic area. It can cause joint laxity on ligaments and fibrous tissue anywhere in the body, including your back, hip joints, knees and ankles, which all become slightly more prone to injury. Its relaxing effect can also mean there is significant movement between pelvic joints which can range from mildly uncomfortably to excruciatingly painful.
Pregnant women may find that they have greater range of movement during pregnancy due to relaxin. This means it is really important not to overstretch when moving or stretching and stay within a normal range of movement. The effects of relaxin are less noticeable in first time mums; more so in subsequent and multiple pregnancies. It can take six months to return to normal levels (a small amount is always present in the body) but longer if you are breastfeeding, so relaxin is also a factor to consider in postnatal exercise prescription.
Oestrogen has many important functions in pregnancy, including promoting growth of various bits and bobs like your uterus, breasts and your left ventricle (how marvellous!) It also has roles in regulating progesterone, the development of your placenta and baby and colostrum production.
Oestrogen also contributes to the increase in your metabolic rate and oedema (fluid retention), which both have an impact on your exercise programme. Regular exercise can help reduce fluid retention. Be mindful of your increased metabolic rate; you’ll need to take on extra calories if you are exercising (200-300 a day from healthy foods) and also have a slightly higher core temperature, so take care when working out not to overheat.
The roles of progesterone, like oestrogen, are many and varied. Levels of both increase steadily as pregnancy progresses. A function which will have a significant impact on working out is the way progesterone makes smooth muscle relax. This includes your oesophagus, blood vessels and digestive system (the reason for some of the delightful pregnancy ailments such as heartburn, varicose veins and piles).
Also impacting your exercise programme is the fact that progesterone helps to stabilise your blood pressure by relaxing your blood vessels and reducing venous return, meaning you may feel dizzy or light headed due to lower blood pressure.
It also increases your sensitivity to CO2, increasing oxygen levels when you breathe through an elevated breathing rate. This means you shouldn’t try and continue at pre-pregnancy exercise levels as you may be panting before you start!
Finally progesterone has the essential role of stopping important things happening before they should, including lactation and contractions.
Insulin resistance increases in all women during pregnancy making their pattern of energy usage similar to that of a mild diabetic. This is actually your body’s way of making sure that blood glucose circulates for longer so that it can be properly absorbed by the placenta and the baby, so is not a bad thing! However, around 2-4% of women will develop gestational diabetes (which only lasts for the duration of the pregnancy) which may cause some birth defects and result in babies having to be delivered early by caesarean.
Gestational diabetes is usually treated through diet and exercise; overweight women are more likely to develop it. If you do suffer your Midwife will advise on treatment, but it will likely include healthy eating and regular exercise; what we should all be doing anyway!
The main thing to be aware of with exercise and pregnancy insulin levels is that regular training encourages increased insulin sensitivity, which could result in a drop in glucose being available to the baby during exercise. Just remember if you are working out to eat regularly and have a healthy snack before and after exercising.
If you have existing diabetes make sure you discuss your management plan with your Midwife so they can give you appropriate advice and support.
Your changing body during pregnancy
As you can see from our quick run down on the hormones there are lots of changes going on in your body during pregnancy, but this doesn’t mean you can’t be active. However, there are a few things to bear in mind. Just to make sure you have all the key information:
Cool as a cucumber During pregnancy your core temperature rises by approximately 0.6 degrees celsius. Your sweat point lowers, enabling you to dissipate heat from yourself and your baby. This, along with a slightly elevated breathing rate, means that you have a fab inbuilt cooling mechanism and overheating is unlikely.
Go with the flow Cardio exercise will not compromise blood flow to your baby. Provided you are working out at a sensible intensity and not for too long (i.e. over an hour and a half) your body will direct blood to your baby ahead of your working muscles. Stop if your muscles feel fatigued.
Added bonus You are still getting all the ‘normal’ benefits of exercise in addition to the ones related to pregnancy. You’ll be boosting your immune system, improving your cardiovascular and muscle fitness and endurance, releasing endorphins and, hopefully, improving your body image.
Put your hands up! Some people say that you shouldn’t raise your hands above shoulder height in later pregnancy, in case the umbilical cord gets wrapped around your baby’s neck. This is an old wives’ tale and you can ignore it. Carry on raising your hands as long as it feels comfortable. You only need to be cautious if you have issues with high blood pressure.
Don’t count on it An old school of thought used to say in pregnancy your heart rate during exercise should not go above 140 BPM. There’s no right or wrong and every woman is different. A bit of a sweat is OK, but try to keep your effort level moderate – at around 60–70 per cent of your maximum heart rate. Don’t measure your heart rate; go by how you feel and make sure you can still hold a conversation (see page xx)
Back in action If you lie on your back (supine) when your bump is big it may put pressure on your vena cava and affect blood flow, making you feel light-headed. This is called ‘supine hypotensive syndrome’. Avoid lying on your back for any length of time and try side and seated positions instead.
Full of hot air During pregnancy your need for oxygen increases, meaning your breathing rate rises. Later in pregnancy it also becomes harder to take a big breath as your belly expands. Moderate your workout intensity so you can breathe comfortably.
Huff and puff Progesterone is a hormone that relaxes smooth muscle and makes you more sensitive to CO2. This may mean your breathing rate increases and you get puffed more quickly. If this happens moderate your intensity.
Working overtime Your resting heart rate (HR) and blood pumped per beat will increase. This means that you should moderate cardio activity as pregnancy progresses. Keep your heart rate up, but make sure you are working at a sensible intensity and not pushing yourself too hard. Also, warm up gradually and steadily decrease intensity at the end of your workout – to bring your heart and breathing rates down gently.
Vascular underfill When you are first pregnant your body becomes less able to quickly divert your blood to where it is needed. This can make you feel dizzy and faint. If you do, adapt your exercise and avoid quick and frequent transitions (floor to standing etc) and being still for long periods.