Exercise during pregnancy and postpartum: a trainer's guide

Is it safe to exercise while pregnant?

Exercise during pregnancy is safe and recommended for most clients without obstetric or medical complications. The American College of Obstetricians and Gynecologists (ACOG) calls physical activity in an uncomplicated pregnancy “safe and desirable” and encourages people to continue or start exercising.^{1American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 1.}

Fears that exercise causes miscarriage, poor fetal growth or premature delivery have not been borne out in uncomplicated pregnancies.^{2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.}

A pregnant client should be under the care of an obstetrician–gynecologist or other obstetric care provider. They should ask that provider about adjusting activity.^{2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.} The trainer’s job is to program within that clearance, watch for warning signs, and refer.

What are the benefits of exercise during pregnancy?

ACOG’s summary of the evidence lists a higher rate of vaginal delivery and lower rates of:^{3American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 3.}

• excessive weight gain during pregnancy
• gestational diabetes
• gestational high blood pressure disorders, including preeclampsia
• preterm birth
• cesarean birth

The same list includes lower birth weight. ACOG notes that people who kept exercising vigorously into the third trimester were more likely to have babies 200–400 g lighter than comparable controls, though without a higher risk of fetal growth restriction.^{3American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 3.}

Observational studies have also linked exercise in pregnancy to shorter postpartum recovery, and physical activity may help prevent depression after birth.^{1American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 1.} The American College of Sports Medicine (ACSM) adds improved mood, less low back pain and less urinary incontinence to the list.^{4Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 400.}

Keep the claims modest when you talk to clients. ACOG notes the evidence is limited, and that exercise has shown only a modest effect on total weight gain, about 1–2 kg.^{3American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 3.},^{5American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 8.}

How much exercise is recommended during pregnancy?

ACOG and ACSM give the following exercise targets:

	Recommendation
Weekly total	At least 150 minutes of moderate-intensity aerobic activity, spread through the week1American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 1.,2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.
Daily target	Build toward at least 20–30 minutes a day on most or all days6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.
Frequency	Typically 3–4 times a week, up to daily7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 409.,8American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 6.
Strength work	Light to moderate resistance training, 30–50 minute sessions, 1–3 times a week9Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 410.
Pelvic floor	Pelvic floor muscle training, such as Kegels, can be done daily9Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 410.

ACOG’s examples of well-studied, safe activities are walking, stationary cycling, aerobic exercise, dancing, resistance exercise with weights or bands, stretching, and water exercise.^{2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.} Benefits are dose-related, so aim for at least the minimum.^{7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 409.}

A client who was sedentary before pregnancy should progress more gradually.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.} A client who already did vigorous training can generally keep going, if they stay healthy and check with their provider.^{1American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 1.},^{10Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 407.}

How do you monitor intensity during pregnancy?

Use perceived exertion or the talk test rather than heart rate alone. Heart-rate responses to exercise can be blunted in pregnancy, so ACOG says ratings of perceived exertion may be the better guide.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.}

• Moderate intensity is about 13–14 (“somewhat hard”) on the 6–20 Borg RPE scale.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.}
• For the talk test, a client who can hold a conversation is probably not overdoing it. If they can’t talk without being out of breath, ease off.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.},^{7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 409.}

Clients who were very active before pregnancy may work at a higher RPE, around 14–17, so prescribe individually and let them adjust day to day.^{11Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 524.} ACOG says regular exercisers with healthy pregnancies should be able to do high-intensity work such as jogging without harm, though no safe upper limit has been established.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.}

Keep these precautions in the session plan:

• High-intensity or prolonged sessions beyond 45 minutes can cause low blood sugar, so eat beforehand or shorten the session.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.}
• Stay well hydrated, wear loose clothing, and avoid high heat and humidity, especially in the first trimester.^{2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.}
• Sessions shouldn’t go past the point of fatigue or reach exhaustion.^{12Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 527.},^{13Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 528.}

When should a pregnant client not exercise?

Contraindications fall into two groups. An absolute contraindication rules exercise out during the pregnancy. A relative contraindication means a physician should evaluate the client before they exercise.^{14Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 526.} The trainer does not decide whether a client with a contraindication can exercise.

NSCA’s Essentials of Personal Training reprints this list from a 2022 ACSM publication, with notes on where the ACOG and Canadian pregnancy guidelines differ:^{14Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 526.},^{12Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 527.}

Absolute contraindications	Relative contraindications
Hemodynamically significant heart disease	Anemia or symptomatic anemia
Incompetent cervix, cervical insufficiency, or cerclage	Cervical dilation
Intrauterine growth restriction	Chronic bronchitis, mild or moderate respiratory disease, or other respiratory disorders
Multiple gestation at risk for premature labor	Eating disorder
Persistent second or third trimester bleeding	Extreme morbid obesity
Placenta previa after 26–28 weeks of gestation	Heavy smoker
Preeclampsia or pregnancy-induced hypertension	History of extremely sedentary lifestyle
Premature labor during the current pregnancy	History of spontaneous preterm birth, premature labor, miscarriage, or fetal growth restriction
Restrictive lung disease	Malnutrition or extreme underweight
Ruptured membranes	Mild or moderate cardiovascular disease
Severe anemia	Orthopedic limitations
Uncontrolled or poorly controlled hypertension	Poorly controlled seizure disorder
Uncontrolled thyroid disease	Poorly controlled type 1 diabetes
Uncontrolled type 1 diabetes	Recurrent pregnancy loss
Unexplained persistent vaginal bleeding, such as in the second or third trimester	Unevaluated maternal cardiac dysrhythmia
Other serious cardiovascular, respiratory, or systemic disorder	Other significant medical conditions

ACOG and the Canadian guideline classify some conditions differently. ACOG treats intrauterine growth restriction, poorly controlled hypertension and poorly controlled hyperthyroidism as relative contraindications. The Canadian guideline treats gestational hypertension as relative, triplets or more as absolute, and twins after 28 weeks as relative.^{12Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 527.} The client’s provider makes the decision.

For screening, ACSM points to the Canadian Get Active Questionnaire for Pregnancy (GAQ-Pregnancy). If a client answers yes to any question, their obstetric provider should complete the matching consultation form before they start or continue exercising.^{15Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 401.} For more on screening in general, see pre-participation screening for new clients.

Warning signs to stop exercise

ACOG and ACSM list the same 10 signs. Any one of them means the client stops exercising and seeks medical advice:^{16American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 5.},^{10Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 407.},^{14Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 526.}

• Vaginal bleeding
• Abdominal pain
• Regular, painful contractions
• Amniotic fluid leakage
• Shortness of breath before exertion
• Dizziness
• Headache
• Chest pain
• Muscle weakness affecting balance
• Calf pain or swelling

NSCA adds: severe headaches, dizziness and disorientation need referral to the client’s health care provider.^{14Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 526.} No exercise with a fever, and see the provider about bleeding, heavy discharge, or swelling in the face and hands.^{13Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 528.}

Which exercises should pregnant clients modify or avoid?

Avoid:

• Contact sports and activities with a high risk of falling, losing balance or abdominal trauma.^{16American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 5.},^{17Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 411.} NSCA’s examples are soccer, basketball, horseback riding, in-line skating, outdoor cycling and plyometric training.^{13Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 528.}
• Scuba diving.^{16American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 5.}
• Exercise in hot conditions, including hot yoga and hot Pilates.^{18Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 412.}
• The Valsalva maneuver (breath-holding under effort), prolonged isometric holds, and motionless standing.^{18Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 412.} NSCA suggests exhaling on the effort.^{11Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 524.}

Modify:

• NSCA suggests a resistance that allows multiple repetitions, such as 12–15.^{12Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 527.} ACOG suggests elite athletes who want to keep training hard consider lifting lighter than before pregnancy, with their provider’s approval.^{8American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 6.}
• As the center of mass shifts, machines can offer more stability than free weights. Do exercises slowly and with control.^{11Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 524.},^{14Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 526.}
• More than 60% of pregnant people get low back pain.^{2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.} Water exercise is a good alternative for clients who have it.^{16American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 5.}

Can pregnant clients exercise lying on their back?

The sources disagree.

• NSCA (2022) says to phase out supine work before the second trimester, because the uterus can restrict blood returning to the heart. Swap in quadruped or side-lying core work and seated options, such as a vertical chest press machine for the bench press.^{11Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 524.}
• ACOG (2020) says supine exercise after 20 weeks may cause low blood pressure, and advises avoiding long periods lying flat.^{2American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 2.},^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.}
• ACSM (12th edition) is the newest of the three. It says the research to date doesn’t link supine exercise to harm to the pregnancy or the fetus. But if a client feels light-headed or uncomfortable, change the position: semi-recumbent, seated, or a pillow under the right hip.^{18Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 412.}

For a conservative approach, keep supine sets short in later pregnancy and switch position at the first sign of light-headedness.

What about diastasis recti and core training?

Diastasis recti is a visible separation of the abdominal muscles. The sources also disagree about which exercises reduce the gap. ACOG (2020) reports that crunches and the drawing-in maneuver reduced the gap after birth.^{5American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 8.} ACSM’s newer edition says drawing-in and pelvic floor exercises widen the gap in people with diastasis recti, and curl-ups and head lifts narrow it.^{18Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 412.} Refer clients with diastasis recti for physical therapy advice; ACSM says trainers should work with that therapist.^{18Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 412.}

When can you start postpartum exercise?

Explain the differences in these timelines to the client.

• ACOG: resume gradually as soon as it’s medically safe. That depends on how the baby was delivered and whether there were complications. Some people can be active again within days, and pelvic floor exercises can start right away.^{5American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 8.}
• NSCA: gradual exercise may begin about 4–6 weeks after a normal vaginal delivery, or about 8–10 weeks after a cesarean with medical clearance.^{13Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 528.}
• ACSM: the client and their health care provider decide together when to resume, and healing times differ by delivery type.^{19Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 413.} Clients who were fitter and trained harder before and during pregnancy may be able to resume sooner.^{20Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 414.}

Regular aerobic exercise while breastfeeding hasn’t been shown to affect milk production or infant growth. Breastfeeding clients may be more comfortable feeding or expressing before a session, and they need to stay hydrated.^{5American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 8.},^{20Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 414.}

When can you run again after having a baby?

The most detailed guidance comes from UK physiotherapists Tom Goom, Gráinne Donnelly and Emma Brockwell, published in 2019.^{21Goom, Donnelly and Brockwell, Returning to running postnatal, p. 1.} They advise no running before 3 months postpartum, and later still if there are pelvic floor symptoms. The aim is a return between 3 and 6 months at the earliest.^{22Goom, Donnelly and Brockwell, Returning to running postnatal, p. 10.} The authors rate that recommendation as expert opinion. The research base is thin.^{23Goom, Donnelly and Brockwell, Returning to running postnatal, p. 28.}

Running is high-impact. One review they cite found high-impact exercise carried a 4.59-fold higher risk of pelvic floor dysfunction than low-impact exercise. After a cesarean, the abdominal fascia has regained only about 51–59% of its original strength by 6 weeks.^{24Goom, Donnelly and Brockwell, Returning to running postnatal, p. 9.}

A staged return to exercise after birth

Their example progression for the first 3 months, and what comes after:^{25Goom, Donnelly and Brockwell, Returning to running postnatal, p. 39.},^{26Goom, Donnelly and Brockwell, Returning to running postnatal, p. 40.}

Weeks after birth	Example activities
0–2	Pelvic floor exercises, basic core work such as pelvic tilts, walking
2–4	Progress walking and core work; consider squats, lunges and bridges
4–6	Low-impact cardio such as a stationary bike or cross-trainer, if comfortable on a saddle
6–8	Power walking, more low-impact volume, light deadlift technique with gradual load increases, scar mobilization
8–12	Swimming, once bleeding has stopped and wounds have healed; spin classes if comfortable
12+	Graded return to running, for clients who pass the readiness tests

For the 6–8 week deadlifts, they suggest starting with no more than the weight of the baby in a car seat (about 15 kg).^{25Goom, Donnelly and Brockwell, Returning to running postnatal, p. 39.}

Readiness tests for running postpartum

Before running, the client should be able to do all of the following without pain, heaviness, dragging or leaking:^{27Goom, Donnelly and Brockwell, Returning to running postnatal, p. 16.}

• Walk for 30 minutes
• Balance on one leg for 10 seconds
• Single-leg squat, 10 reps each side
• Jog on the spot for 1 minute
• Forward bounds, 10 reps
• Hop on the spot, 10 reps each leg
• Single-leg “running man” (opposite arm and knee drive), 10 reps each side

They also suggest aiming for 20 reps each of single-leg calf raises, single-leg bridges, single-leg sit-to-stands and side-lying hip abduction. Weakness here isn’t a reason to hold back running. It shows where to direct strength work.^{28Goom, Donnelly and Brockwell, Returning to running postnatal, p. 17.}

Once a client passes, start small: around 1–2 minutes of easy running. Build volume before intensity.^{29Goom, Donnelly and Brockwell, Returning to running postnatal, p. 24.},^{26Goom, Donnelly and Brockwell, Returning to running postnatal, p. 40.} Hold off running with a buggy (stroller) until the baby is at least 6–9 months old.^{30Goom, Donnelly and Brockwell, Returning to running postnatal, p. 27.}

Pelvic floor symptoms that mean referral

The guideline says every new mother should be offered a pelvic health assessment with a specialist physiotherapist from 6 weeks after birth.^{22Goom, Donnelly and Brockwell, Returning to running postnatal, p. 10.} Refer to a pelvic health physiotherapist if, before or after starting to run, a client reports:^{31Goom, Donnelly and Brockwell, Returning to running postnatal, p. 12.}

• Heaviness or dragging in the pelvic area, which can be associated with prolapse
• Leaking urine, or trouble controlling bowel movements
• A pendular abdomen or a noticeable gap along the midline of the abdomen
• Pelvic or lower back pain
• Ongoing or increased bleeding beyond 8 weeks after birth that isn’t linked to a period. Bleeding during or after exercise goes back to the client’s care provider.^{32Goom, Donnelly and Brockwell, Returning to running postnatal, p. 13.}

The authors call these problems “common but not normal”. They don’t expect fitness professionals to run the clinical tests, only to know the signs and send the client to the right health professional.^{33Goom, Donnelly and Brockwell, Returning to running postnatal, p. 3.}

How to coach pregnant and postpartum clients

1. Get clearance, then screen. Ask the client to check with their obstetric care provider, and use a pregnancy-specific questionnaire such as GAQ-Pregnancy.^{15Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 401.} Re-check if anything changes.
2. Teach the warning signs in the first session. Any one of the 10 ends the session.
3. Use RPE and the talk test, and keep the plan flexible. When the full plan isn’t possible, do what can be done.^{10Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 407.},^{7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 409.}
4. Replace contact, fall-risk and long supine work with stable, seated, side-lying or water-based options.
5. After birth, don’t restart where the client left off. Build up in stages, and hold running until at least 3 months and passed readiness tests.
6. Have a pelvic health physiotherapist to refer to and a way to reach the client’s care provider. Diagnosing symptoms is outside a trainer’s scope.

Common questions about pregnancy and postpartum exercise

Can a client start exercising for the first time while pregnant?

Yes, with their provider’s clearance. ACOG encourages previously inactive people to start, with a more gradual progression than for someone who was already exercising.^{1American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 1.},^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.} ACSM recommends building duration and intensity up to the recommended amount, rather than training irregularly.^{7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 409.}

Is lifting weights safe during pregnancy?

ACSM says research supports the safety of resistance training in pregnancy. It recommends light to moderate intensity, avoiding the Valsalva maneuver, and contracting the pelvic floor before and during heavy lifts.^{9Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 410.} Elite athletes who want to keep lifting heavy should get their provider’s approval and consider lighter loads.^{8American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 6.}

Do I need to keep a pregnant client’s heart rate under 140?

Not as a hard rule. ACOG’s sample program lists 60–80% of age-predicted maximum heart rate, “usually not exceeding 140 beats per minute”.^{8American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 6.} But ACOG also says perceived exertion may be a better guide than heart rate in pregnancy, alongside the talk test.^{6American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 4.}

How soon after a C-section can you exercise?

NSCA suggests gradual exercise from about 8–10 weeks, with medical clearance.^{13Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 528.} ACOG and ACSM leave timing to the client’s provider, based on how they’re healing.^{5American College of Obstetricians and Gynecologists, Physical Activity and Exercise During Pregnancy and the Postpartum Period, p. 8.},^{19Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 413.} For running, the same 3-month minimum applies, and the return-to-running guideline lists a cesarean or perineal scar among the risk factors for problems when returning.^{22Goom, Donnelly and Brockwell, Returning to running postnatal, p. 10.},^{34Goom, Donnelly and Brockwell, Returning to running postnatal, p. 11.}