The physiological changes occurring during pregnancy that may affect activity and exercise can be divided into four main sections (Paisley, Jo & Price, 2003):
- Cardiovascular shifts such as cardiac output increasing by up to 50%, resting heart rate increasing and blood volume rising by approximately 45%.
- Respiratory changes such as minute ventilation increasing by 50% and an increase in tidal volume and resting oxygen demand.
- Metabolic changes including required energy intake increasing by 300kcal/day and plasma glucose significantly decreasing after 45 minutes or more of exercise.
- Musculoskeletal adaptations such as an increase in joint laxity, weight gain and increase of lumbar lordosis and thoracic kyphosis.
Benefits of Activity & Exercise during Pregnancy
A 2006 Cochrane Review concluded that, although regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness, there is a lack of evidence regarding risks and benefits for the woman or her baby (Kramer & McDonald, 2006). However, exercise is associated with fewer discomforts of pregnancy and exercising earlier in pregnancy is associated with fewer negative symptoms later on in pregnancy (Sternfeld, 1997). The lack of evidence for any harmful effects of exercise on pregnancy outcome indicates that, for healthy, well-nourished women, exercise during pregnancy is safe (ACOG, 2002).
Contraindications & Cautions to Exercise in Pregnancy
If the woman has been a regular exerciser prior to becoming pregnant, then if she wishes, she can continue her program during her first trimester (weeks 1-14). During this time, lay down the groundwork for good posture and technique for the coming months.
Through the later stages of pregnancy, adaptations will need to be made to any program to keep it safe and comfortable. There are, however, a number of published contraindications to exercise in pregnancy from The American Congress of Obstetricians and Gynecologist (ACOG), which are reflected in a statement from the RCOG (2006).
Absolute Contraindications to Aerobic Exercise during Pregnancy (ACOG)
- Hemodynamically significant heart disease
- Restrictive lung disease
- Incompetent cervix/cerclage
- Multiple gestation at risk for premature labor
- Persistent second or third trimester bleeding
- Placenta previa after 26 weeks' gestation
- Premature labor during the current pregnancy
- Ruptured membranes
- Pregnancy-induced hypertension
Relative Contraindications to Aerobic Exercise during Pregnancy (ACOG)
- Severe anemia
- Unevaluated maternal cardiac arrhythmia
- Chronic bronchitis
- Poorly controlled type I diabetes
- Extremely obese or underweight
- History of extremely sedentary lifestyle
- Intrauterine growth restriction in current pregnancy
- Poorly controlled hypertension/preeclampsia
- Orthopedic limitations
- Poorly controlled seizure disorder
- Poorly controlled thyroid disease
- Heavy smoker
In addition, remember to continually screen your clients and gain feedback from them to ensure they are comfortable, and be alert for any warning signs such as calf pain or swelling, dyspnoea before exertion, chest pain, pelvic girdle pain and muscle weakness.
Practical Gym Equipment Considerations
Most equipment in the gym can be used comfortably in early pregnancy, but may become uncomfortable or inaccessible as pregnancy progresses. Machines such as the stepper and cross trainer could take the pelvis and lower back out of alignment and cause a grinding feeling, so reduce range of movement accordingly and coach the woman to keep hips level. Ensure feet are straight too, to minimize twisting of the pelvis.
With the cycle, as the woman gets bigger, it may be necessary to lower the saddle to get on and off more easily and to help keep the pelvis stable. Higher handlebars encourage a more upright posture, allow space for the growing baby and help alleviate lower-back pain. The treadmill is a good choice throughout pregnancy.
The rower will become more difficult to use as pregnancy progresses. Knee alignment may be compromised as they bow outwards to avoid the growing abdomen. As the body gets larger, the pelvis becomes more unstable and the center of gravity changes, so allow more time to get on and off equipment generally, and moving from one machine to another. There is a chance of falling if the woman tries to rush.
The use of dumbbells and barbells also needs careful consideration. Reduced joint stability requires that technique is perfect throughout each repetition, ensuring that there is no joint hyperextension or misalignment. Reducing speed of performance can help the woman maintain alignment.
Wide-stance exercises such as wide squats and large side steps could increase discomfort or dysfunction in the pelvis, so these movements should be performed at a moderate, comfortable width. The large, powerful kicking and punching moves in a ‘combat’ style session are inappropriate for the same reason. With Pilates and yoga-style activities and stretches, reduce range of movement to avoid hyperextension and eliminate prone and supine postures. After about 16 weeks, guidelines recommend no lying on the back due to the risk of supine hypotension.
Try to keep intensity of CV training moderate: 6-7 (on CR10 scale) or 12-14 (on Borg scale). Intervals are a great way of moderating intensity. With resistance training, from about 14-16 weeks onwards, reduce weights to around 70% of pre-pregnancy resistance and aim for 10-15 repetitions to stay comfortable and maintain technique.
- ACOG Committee Opinion No. 267. (2002; Reaffirmed 2009). Exercise during pregnancy and the postpartum period. Retrieved from: http://mail.ny.acog.org/website/SMIPodcast/Exercise.pdf.
- Kramer, M.S. & McDonald, S.W. (2006). Aerobic exercise for women during pregnancy. Cochrane Database of Systematic Reviews, 3: 000180.
- Paisley, T.S., Jo, E.A. & Price, R.J. Jr. (2003). Exercise during pregnancy: A practical approach. Current Sports Medicine Reports, 2: 325-330.
- RCOG. (2006). Exercise in pregnancy statement No. 4. Retrieved from: http://www.rcog.org.uk/womens-health/clinical-guidance/exercise-pregnancy.
- Sternfeld, B. (1997). Physical activity and pregnancy outcome, review and recommendations. Sports Medicine, 23(1): 33-47.
Source: Fitpro Network