Exercise During Pregnancy: Key Considerations

• Physical activity is bodily movement from skeletal muscle that results in energy expenditure.
• Physical activity involves a complex phenomenon quantified by frequency, intensity, duration, and type that increases energy expenditure.
• Leisure time physical activity (LTPA) consists of activities during free time.
• Occupational physical activity (OPA) consists of activities occurring during a job.

Physiology of Exercise & Pregnancy

• Exercise during pregnancy involves multiple organ systems.
• Studies of exercise during human pregnancies are inconsistent so animal studies become important.
• Key questions regarding exercise during pregnancy are does it have any effects to the baby, induce premature labor, have risk of injury to the mother and what exercises can be done.
• Three key considerations for exercise during pregnancy are hyperthermia, hydration, and water retention.

Hyperthermia

• Hyperthermia has a a potential teratogenic effect.
• Studies show less increase in body temperature in pregnant women.

Hydration

• Pregnant women need adequate fluid intake before, during, and after exercise.
• It is recommended to drink 1 pint of liquid before exercise.
• It is recommended to drink 1 cup every 20 minutes during exercise.
• It is recommended to drink 1-2 liters after exercise.
• High air temperature and humidity require special considerations.
• Need low humidity when the temperature is over 80 degrees and humidity exceeds 50%.
• Avoid heat-related injury by exercising early in the morning or later in the day.

Water Retention

• Water retention typically occurs in the 3rd trimester.
• Symptoms of water retention are ankle and wrist swelling.
• Water retention increases the risk of injury.

Cardiac Output

• Cardiac output is the amount of blood ejected by the heart in 1 minute measured in liters.
• Normal cardiac output is about 5L/minute.
• Cardiac output is determined by multiplying heart rate by stroke volume.
• Stroke volume is ventricular volume measured by filling pressure and ventricular compliance.
• Stroke volume is the volume of blood ejected during systole (contracts).
• The equation for Cardiac Output is CO = HR x SV.
• Cardiac output increases 30-50% during pregnancy.
• Cardiac output may decrease in the 3rd trimester when in a seated or supine position.
• Both heart rate and stroke volume increase during pregnancy.
• Stroke volume increases due to an increase in heart size.
• Heart rate increases due to hormonal and nervous system changes.

HR and BP

• Resting heart rate (RHR) increases in the first few weeks by about 7 bpm.
• RHR plateaus around 32 weeks at about 16 bpm high.
• Changes in fetal heart rate are transient and show no bad effects.
• Mean arterial blood pressure (BP) drops during pregnancy, reaching a low at mid-term.
• Blood pressure returns to normal by delivery.
• Peripheral resistance decreases.

Changes in Body Position

• Pressure from the uterus while in a supine position has consequences.
• Compression of the inferior vena cava and abdominal aorta can occur.
• Cardiac output can drop.
• Exercise in the supine position and with atmospheric changes are causes for concern.
• Motionless standing is a cause for concern.

Basal Oxygen Consumption (VO2 Rest)

• Basal oxygen consumption increases during pregnancy.
• Lung tidal volume increases, causing breath to become deeper and faster from changed hormone levels.
• Residual volume, tidal volume, and total lung capacity/volume are all affected.

Dyspnea During Exertion

• Dyspnea during exertion includes perceived shortness of breath.
• There is a decrease in residual volume and expiratory reserve volume.
• Total lung volume decreases.
• The diaphragm elevates from the uterus.
• The ability to withstand apnea is reduced.

Balance and Flexibility

• The weight of the growing fetus causes lumbar lordosis and changes in the center of gravity.
• The risk of falls increases.
• Connective tissue changes due to the hormone relaxin.
• The risk of sports injuries increases.

Guidelines for Exercise During Pregnancy

• Get clearance from a doctor before exercising.
• Exercise during pregnancy protects offspring against long-term neurodegenerative diseases.
• Prenatal exercise may improve brain plasticity.
• Exercise during pregnancy can decrease toxic protein deposits, inflammation, and oxidative stress. -Exercise during pregnancy can help ward off Alzheimer's and other diseases.

Recommendations from ACOG

• All pregnant women without contraindication should be encouraged to exercise.
• Choose activities that minimize the risk of loss of balance or fetal trauma.
• Set reasonable conditioning goals to maintain good fitness.
• Adverse pregnancy or neonatal outcomes are not increased with exercise.
• Moderate exercise during lactation does not affect infant growth.
• Pelvic floor exercises in post-partum period are beneficial.

Absolute Contraindications

• Significant heart disease.
• Restrictive lung disease.
• Preeclampsia (HBP).
• Risk of premature labor.
• Incompetent cervix.
• Persistent 2nd or 3rd trimester bleeding.
• Placenta Previa.
• Ruptured membranes.

Relative Contraindications

• Heavy smoker.
• Severe anemia.
• HBP.
• Cardiac arrhythmias.
• Chronic bronchitis.
• Sedentary lifestyle.
• Type 1 diabetes.
• Morbid obesity.
• Low body weight (BMI < 12).
• Intrauterine growth restriction.
• Orthopedic limits.
• Seizure disorder.
• Hyperthyroidism.

Signs to Stop Exercising

• Dyspnea before exertion.
• Dizziness.
• Headache.
• Angina.
• Muscle weakness.
• Calf pain/swelling.
• Vaginal bleeding.
• Preterm labor.
• Decreased fetal movement.
• Amniotic fluid leakage.

FITT-VP Principle

• Frequency: 3-5 times per week.
• Intensity: Moderate.
• Time: Less than or equal to 45 minutes per session.
• Type: Low-impact, aerobic activities are ideal.
• Volume.
• Progression.

Getting Started

• If already active, remain active.
• Follow the FITT-VP principle.
• If previously inactive, wait until the 2nd semester.
• Start slowly & progress gradually.
• Set reasonable goals without competition.
• Choose activities that minimize falling.

Exercise Intensity

• Resting heart rate increases, but maximum heart rate decreases.
• Modify conventional target heart rate calculations.
• Use Borg's Rating of Perceived Exertion Scale.
• Maternal Age vs. Target Heart Rate (bpm):
  • Under 20: 140-155
  • 20-29: 135-150
  • 30-39: 130-145
  • Over 40: 125-140
• Use the "Talk Test" to gauge intensity.

Gradual Progression

• During the 2nd trimester, increase intensity by 10-15%.
• Increase frequency to 5 days/week.
• Increase duration to 40-45 minutes/session.
• Be aware of physiological changes that can affect the ability to exercise, such as ligament changes, balance issues, cardiac output, and metabolic rate.

Pregnancy Nutrition

• Five food groups are vital.
• Grains, fruits, vegetables, protein, and dairy are essentials.
• Oils & fats are important nutrients, but not a food group.
• Vitamins & minerals play an important role in all body functions.
• There is an increased need for folic acid and iron during pregnancy.
• Prenatal vitamins ensure these needs are met.
• A well-balanced diet supplies all other vitamins & minerals needed.

Nutrient Needs by Trimester

• 1st trimester: Folate (folic acid) and iodine.
• 2nd trimester: Iron.
• 3rd trimester: Choline, Vitamin D, calcium, and magnesium.

What is Folic Acid?

• Folic acid is a B vitamin, also known as folate.
• It is important for neural tube formation in the fetus.
• Sources of folic acid are fresh raw fruits, vegetables, leafy greens, fortified juices, and cereals.
• Iodine helps with thyroid function in the mother.
• Low iodine levels can lead to developmental delays.
• Sources of iodine are iodized salt, shellfish, and seaweed.

Why Iron is Important

• Iron is important for hemoglobin formation.
• You need 2x as much iron to help make more blood.
• Vitamin C improves iron absorption.
• Sources of iron are lean meats, fish, dried beans, and fortified foods.
• Calcium and magnesium are used to build the baby's bones and teeth.
• Dairy is the best source for calcium.
• Beans are the best source for magnesium.
• Non-dairy sources of calcium include broccoli, dark leafy greens, sardines, or supplements.
• Calcium requirements:
  • Over 19 y/o: 1,000 mgs/day.
  • 14-18 y/o: 1,300 mgs/day.
• Vitamin D works with calcium and helps with skin and eyesight of the baby.
• Good sources of vitamin D are fortified milk, fatty fish (like salmon), sunlight exposure, and supplements.

What About Fish?

• Fish is high in Omega-3 fatty acids.
• During pregnancy and breastfeeding, aim for at least 2 servings per week.
• Watch out for mercury.
• Do not eat shark, swordfish, mackerel, or tilefish.
• Limit white tuna to 6 oz/week.
• Choline is important in the formation of neurotransmitters & directly relates to fetal brain development.
• Sources of Choline are shrimp, egg yolks, fish, and turkey.

Weight Gain

• Weight gain depends on the individual's pre-pregnancy fitness and body composition.
  • If normal: 25-35 lbs.
  • If underweight: More.
  • If overweight: Less.
• Weight ranges for a full-term pregnancy
  • Underweight: 28-40 pounds.
  • Normal: 25-30 pounds.
  • Overweight: 15-25 pounds.
  • Obese: 11-20 pounds.

Changes in Energy Requirements

• Energy needs are different for each trimester
  • First Trimester - 85 Extra Calories.
  • Second Trimester - 285 Extra Calories.
    • Third Trimester - 475 Extra Calories.
    • Average of 285 per day overall
• Overweight moms have an increased risk
  • Gestational diabetes.
    • HBP
    • Preeclampsia
    • Preterm birth
• Cesarean section
  • Birth defects
  • Birth injury.
  • Childhood obesity.
• Listeriosis
  • Listeria infection is a foodborne bacterial illness that can be very serious for pregnant women and people with impaired immune systems. -Listeria infection is most commonly contracted by eating improperly processed deli meats and unpasteurized milk products. -Pregnant women are 13x's at a greater risk than others. -Listeria bacteria can survive refrigeration and even freezing
  • Avoid these foods: -Unpasteurized milk -Hot dogs, lunchmeats, and cold cuts unless heated
  • Paté and meat spreads -Smoked seafood -Raw or undercooked seafood, eggs, and meats

Exercise During Postpartum

• Pregnancy changes persist 4-6 weeks after delivery.
• Resume pre-pregnancy activity levels gradually.
• Some weight loss while breastfeeding is okay.
• Returning to activity can reduce postpartum depression.
• Initiate kegel exercises.

Benefits of Exercise After Pregnancy

• Promote weight loss, particularly when combined with reduced caloric intake
• Improve your cardiovascular fitness
• Restore muscle strength & tone
• Condition your abdominal muscles
• Boost your energy level
• Improve your mood
• Relieve stress
• Help prevent/promote recovery from postpartum depression
• Better yet, including physical activity in your routine helps you set a positive example for your child and in the years to come

Exercise and Breast-Feeding

• No known adverse effects on volume or composition
• No known negative effects on infant growth
• Some research suggests that high-intensity exercise may produce lactic acid accumulation in breast milk
• Feed baby or express/pump milk before exercise
• In the past, wait 6 weeks to start exercising after child birth.
• If there were no complications during vaginal delivery, it's safe to start as soon as you feel ready -If a C-section was done, ask your doctor when its safe to begin.

Physical Activity Goals

• Department of Health and Human Services recommends at least 150 minutes a week of moderate-intensity aerobic activity

Consider these guidelines for returning to activity/exercising after pregnancy

• Take time to warm up and cool down
• Begin slowly and increase your pace gradually
• Drink plenty of fluids
• Wear a supportive bra, and if you’re breastfeeding, wear nursing pads in case your breasts leak
• Avoid excessive fatigue
• Stop exercising if you feel pain
• Try low impact exercises with postpartum exercise class at a local fitness club.
• Use kegel exercises to tone your pelvic floor muscles to strengthen the abdominal muscles
• Finding time for physical activity is challenging
• Hormonal changes may lead to sedentary behavior
• Schedule time for physical activity
• Exercise with a friend to stay motivated

Maternal Exercise, Epigenetics, and Offspring Health

• There are 7 great benefits of pregnancy exercise.
• Only 10% of pregnant mothers get the recommended amount of exercise, and OB's are inconsistent.

Epigenetics Overview

• study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence
• Gene Expression- going from a gene to function

Areas to Study

• Cardiophysiology
• Precautions
• Gains and Benefits
• Nutrition
• Testing and Programing
• Postpartum
• Cardiophysiology -Stroke volume -Heart Rate -Cardiac output -Blood pressure -Oxygen consumption -Lactic acid -Adensosine Triphosphate

Cautions

• Balance -The center of gravity changes
• Relaxin hormone releases and causes joints to become loose
• Baby Weight gain/loss
• CV Dysfunction
  • Thermodynamic -Compromises cardiac output -Hyperthermia -Hydration -Water Retention -Occupational physical activity

Gains/Benefits

• Mom
• Weight maintenance
• Better mood
• Better labor
• Better recovery

Baby

Nutrition

• About 300 extra calories a day depends on the exercise

Testing and Programing

• Frequency, intensity, time, type -High-intensity interval training -Vigorous followed by recovery -Progressive resistance training -Progression through activity throughout the training ###Postpartum
  • Issues
• Barriers -Significance

Research

• Mom Baby

Short-term

• Improving pregnancy itself

Long-term

• More physical activity leads to less instances of diabetes, hypertension or obesity.

This lesson covers important considerations for exercise during pregnancy, including the influence of hyperthermia, hydration, and water retention. It addresses key questions, potential risks, and suitable exercises during pregnancy. It also differentiate between leisure time and occupational physical activity.