Exercise and Breastfeeding

By Kelly Bonyata, IBCLC

Moderate exercise improves a mother’s health and has a positive effect on her emotional well-being. Some of the benefits include:

• Higher level of cardiovascular fitness
• Improved blood lipid profiles and insulin response
• A feeling of well-being from improved energy and reduced stress levels
• Enhanced maternal-infant relationship
• Alleviation of depression symptoms in those with major depressive disorders

Research has shown that moderate exercise does not affect milk supply, milk composition, or baby’s growth. Exercising to exhaustion may have a short-term effect on lactic acid and IgA content of a mother’s milk (more details below).

Does exercise affect milk supply or nutrient content?

No. Studies have shown no difference in milk production or nutrient composition or babies’ weight gain. One study showed a slight increase in milk supply for the women who exercised regularly, but because of the small size of the study this increase may not be significant.

Does exercise affect immunologic factors in milk?

A couple of small studies have shown that there is no difference in immunologic factors after moderate exercise, but that IgA levels are decreased short-term after exhaustive exercise. Most breastfeeding mothers do not exercise to exhaustion, but for those that do so and breastfeed soon after, a decrease in IgA levels in one feeding per day is unlikely to be significant.

More details: In 1997, a study by Gregory et al found that IgA levels in breastmilk were decreased for a short time (10-30 minutes) after mom had exercised strenuously (“exhaustive exercise”), but that levels had returned to normal within an hour. They also observed that IgA levels increased after the breast had been emptied, whether or not mom had been exercising strenuously. In 2003, Lovelady et al looked at immunologic factors (IgA, lactoferrin, lysozyme) in breastmilk after moderate exercise, and found no difference in the milk of exercising and non-exercising mothers.

Does lactic acid increase in breastmilk after exercise?

Research has not shown a noticeable increase in lactic acid buildup after moderate exercise (50% & 75% intensity). The lactic acid in breastmilk does increase somewhat if mom exercises to maximum (100%) intensity, also described as exhaustive exercise. This increase may be present up to 90 minutes post-exercise. There are no known harmful effects for the baby.

Will baby refuse the breast after mom exercises?

Most studies have found no difference in acceptance of the breast, even after maximum intensity exercise.

Although a highly publicized 1992 study indicated that baby might fuss or refuse expressed milk from a mom who had been exercising at 100% intensity, the results were questionable because the babies were fed the milk by dropper (unfamiliar to these babies), and the mothers reported that the babies had not had problems with nursing after exercise in the past. A more recent study showed no change in infants’ acceptable of mom’s milk an hour after exercise, even for the moms who exercised at maximum intensity (and thus did have a slight increase in lactic acid in their milk).

If baby seems to object to the taste of mom’s milk after strenuous exercise, keep in mind that it might have nothing to do with the exercise – baby might be distracted or objecting to the salty taste of sweat on your breast, etc. If this happens consistently, mom might try expressing a little milk (3-5 mL from each breast) before nursing baby, postponing feeding for a half hour to let the lactic acid levels subside, and/or decreasing workout intensity a bit in the future.

Exercise guidelines for breastfeeding mothers

• For your own comfort, you may wish to nurse before exercising and wear a good, supportive bra (especially during strenuous exercises such as running, jumping, etc).
• Some babies don’t like nursing when mom has been sweating (due to the salt on mom’s skin) so you may wish to rinse your breasts or take a shower before nursing.
• If you regularly lift weights or do other exercises involving repetitive arm movement and you develop plugged ducts, cut back and start again more slowly.
• Keep yourself hydrated.

Additional information

More exercise-related FAQs

• Can I lose weight while breastfeeding?
• Swimming & chlorinated swimming pools
• Hot tubs
• Insect repellent
• Scuba diving
• Sunscreen & self-tanning products
• Tanning

The Active Mommy Conundrum: Can Exercise Harm Breastfeeding? (see also Part 2) by Taryn Barrette, RD and Jane Heinig, PhD, IBCLC

Research

Daley AJ, et al. Maternal Exercise and Growth in Breastfed Infants: A Meta-analysis of Randomized Controlled Trials. Pediatrics 2012. doi: 10.1542/peds.2011-2485. Published online June 18, 2012.
“It appears that mothers can exercise and breastfeed without detriment to the growth of their infants, but this is based on limited evidence, and more research is required before this finding is confirmed.”

Lovelady C. Balancing exercise and food intake with lactation to promote post-partum weight loss (Review). Proc Nutr Soc. 2011 May;70(2):181-4. Epub 2011 Feb 24.
“Moderate aerobic exercise of 45 min/d, 5 d/week improved cardiovascular fitness, plasma lipids and insulin response; however, it did not promote post-partum weight loss. Breast milk volume and composition were not affected. The effect of exercise with energy restriction in overweight women on the growth of their infants has also been studied. At 1 month post-partum, women restricted their energy intake by 2092 kJ/d and exercised 45 min/d, 4 d/week for 10 weeks. Women in the diet and exercise group lost more weight than the control group (4·8 (sd 1·7) kg v. 0·8 (sd 2·3) kg); however, there were no differences in infant growth. Based on the current evidence, it is recommended that once lactation is established, overweight women may restrict their energy intake by 2092 kJ/d and exercise aerobically 4 d/week to promote a weight loss of 0·5 kg/week.”

Blumenthal JA, et al. Exercise and pharmacotherapy in the treatment of major depressive disorder. Psychosom Med. 2007 Sep-Oct;69(7):587-96. Epub 2007 Sep 10.
“The efficacy of exercise in patients seems generally comparable with patients receiving antidepressant medication and both tend to be better than the placebo in patients with MDD.”

Su D, Zhao Y, Binns C, Scott J, Oddy W. Breast-feeding mothers can exercise: results of a cohort study. Public Health Nutr. 2007 Oct;10(10):1089-93. Epub 2007 May 22.
“Exercise does not affect breast-feeding outcomes at the usual levels of activity undertaken by mothers. Breast-feeding and exercise are important for maintaining and promoting health, and this study provides reassurance to health professionals wishing to encourage mothers to continue both behaviours.”

Bopp M, Lovelady C, Hunter C, Kinsella T. Maternal diet and exercise: effects on long-chain polyunsaturated Fatty Acid concentrations in breast milk. J Am Diet Assoc. 2005 Jul;105(7):1098-103.
“These results suggest that women consuming adequate amounts of LC-PUFA can exercise moderately without decreasing the LC-PUFA in their breast milk.”

Lovelady CA. The impact of energy restriction and exercise in lactating women (Review). Adv Exp Med Biol. 2004;554:115-20.
“Exercise improves cardiovascular fitness, plasma lipids, and insulin response in lactating women. However, exercise alone, without caloric restriction, does not promote weight loss. Once lactation is established, over-weight women may restrict their energy intake by 500 kcal/day to promote a weight loss of 0.5 kg/week without affecting the growth of their infants. Moderate exercise does not affect maternal immune status or levels of sIgA, lactoferrin, and lysozyme in human milk. Further research is needed to determine the effect of exercise and energy restriction on maternal bone health and immune status and composition of human milk.”

Lovelady CA, Fuller CJ, Geigerman CM, Hunter CP, Kinsella TC. Immune status of physically active women during lactation. Med Sci Sports Exerc. 2004 Jun;36(6):1001-7.
“The results of this study suggest that women may exercise moderately during lactation and increase their fitness level without impairing their immune function.”

Rich M, Currie J, McMahon C. Physical exercise and the lactating woman: a qualitative pilot study of mothers’ perceptions and experiences. Breastfeed Rev. 2004 Jul;12(2):11-7.
“The main themes to emerge from the content analysis of the qualitative data included perceived well-being from improved energy and stress levels, and weight control.”

Lovelady CA, Hunter CP, Geigerman C. Effect of Exercise on Immunologic Factors in Breast Milk. Pediatrics 2003 February;111(2):e148-e152.
This study found that nursing mothers who “exercis[ed] aerobically at least 30 minutes/day for 3 days/wk had a higher level of cardiovascular fitness. In addition, there were no significant differences in the concentrations of IgA, lactoferrin, or lysozyme after moderate exercise compared with sitting rest.”

Larson-Meyer DE. Effect of Postpartum Exercise on Mothers and their Offspring: A Review of the Literature. Obes Res. 2002 Aug;10(8):841-53.
“In lactating women, several studies have collectively determined that neither acute nor regular exercise has adverse effects on a mother’s ability to successfully breast-feed.”

Wright KS, Quinn TJ, Carey GB. Infant acceptance of breast milk after maternal exercise. Pediatrics. 2002 Apr;109(4):585-9.
“These data support the hypothesis that moderate or even high-intensity exercise during lactation does not impede infant acceptance of breast milk consumed 1 hour postexercise.”

Cary GB, Quinn TJ. Exercise and lactation: are they compatible? (Review) Can J Appl Physiol. 2001 Feb;26(1):55-75.
“Human studies suggest no detrimental effect of exercise during lactation on milk composition and volume, infant growth and development, or maternal health. Studies also demonstrate improved cardiovascular fitness in lactating, exercising women and suggest a quicker return to pre-pregnancy body weight and a more positive sense of well-being, compared to sedentary controls.”

Lovelady CA, Williams JP, Garner KE, Moreno KL, Taylor ML, Leklem JE. Effect of energy restriction and exercise on vitamin B-6 status of women during lactation. Med Sci Sports Exerc. 2001 Apr;33(4):512-8.
“Energy restriction and exercise from 4 to 14 wk postpartum in overweight, breastfeeding women consuming adequate dietary intakes and 2.0 mg of supplemental vitamin B-6 does not adversely affect vitamin B-6 status or infant growth.”

Babyak M, et al. Exercise treatment for major depression: maintenance of therapeutic benefit at 10 months. Psychosom Med. 2000 Sep-Oct;62(5):633-8.
“Among individuals with MDD, exercise therapy is feasible and is associated with significant therapeutic benefit, especially if exercise is continued over time.”

McCrory MA, et al. Randomized trial of the short-term effects of dieting compared with dieting plus aerobic exercise on lactation performance. Am J Clin Nutr 1999 May;69(5):959-67.
“Short-term weight loss (1 kg/wk) through a combination of dieting and aerobic exercise appears safe for breast-feeding mothers and is preferable to weight loss achieved primarily by dieting because the latter reduces maternal lean body mass. Longer-term studies are needed to confirm these findings.”

Quinn TJ, Carey GB. Does exercise intensity or diet influence lactic acid accumulation in breast milk? Med Sci Sports Exerc. 1999 Jan;31(1):105-10.
“In lactating women whose caloric needs are being met: 1) dietary carbohydrate intake, within a practical range, does not influence lactic acid levels in breast milk at rest or after exercise; 2) lactic acid appearance in the milk is a function of exercise intensity; and 3) moderate intensity exercise will not increase breast milk lactic acid levels.”

Fly AD, Uhlin KL, Wallace JP. Major mineral concentrations in human milk do not change after maximal exercise testing. Am J Clin Nutr. 1998 Aug;68(2):345-9.
“In conclusion, maximal exercise did not alter concentrations of phosphorus, calcium, magnesium, potassium, or sodium in milk. Thus, with respect to mineral concentrations in milk, there is no contraindication for exercise during lactation.”

Dewey KG. Effects of maternal caloric restriction and exercise during lactation (Review). J Nutr 1998 Feb;128(2 Suppl):386S-389S.
“Gradual weight loss (2 kg/mo) [4.4 lbs/mo] seems to have no adverse effect on milk volume or composition, provided that the mother is not undernourished and is breast-feeding her infant on demand. Aerobic exercise improves cardiovascular fitness and does not affect milk energy transfer to the infant, but exercise alone is not likely to increase the rate of weight loss unless dietary intake is controlled. Less information is available on the effect of rapid weight loss. Data from a recent randomized intervention trial indicate that a short-term (11 day) energy deficit of 35%, achieved by dieting or a combination of dieting and increased exercise, results in weight loss >1 kg/wk and does not adversely affect lactation. Exercise enhances maintenance of lean body mass and is therefore a recommended component of any weight loss program. Maternal plasma prolactin concentration generally increases under conditions of negative energy balance, which may serve to protect lactation. Further research is required on the longer-term effect of energy restriction and on the effects of energy balance in lactating women with low fat reserves.”

Carey GB, Quinn TJ, Goodwin SE. Breast milk composition after exercise of different intensities. J Hum Lact. 1997 Jun;13(2):115-20.
“Milk LA [lactic acid] after the 100% intensity session was significantly elevated through 90 minutes postexercise, while there was no significant increase in milk LA at any collection time after the 50% or 75% intensity sessions. There were no significant differences in milk pH, lipid, ammonium, or urea measurements after any of the exercise sessions. These data show that unlike maximum intensity exercise, moderate intensity exercise does not increase breast milk LA content.”

Gregory RL, Wallace JP, Gfell LE, Marks J, King BA. Effect of exercise on milk immunoglobulin A. Med Sci Sports Exerc. 1997 Dec;29(12):1596-601. This study observed short-term decreased IgA levels in breastmilk after exhaustive exercise. “Milk IgA concentrations increased significantly in both exercise and resting control groups after the breasts were emptied, suggesting that breast emptying stimulated milk IgA synthesis. The results provide evidence that exercise alters milk IgA and IgA1 concentrations for 10-30 min after exhaustive exercise, but recovers by 1 h, and provide additional support for exercise effects on the mucosal immune system.”

Lovelady CA, Nommsen-Rivers LA, McCrory MA, Dewey KG. Effects of exercise on plasma lipids and metabolism of lactating women. Med Sci Sports Exerc. 1995 Jan;27(1):22-8.

Dewey KG, et al. A randomized study of the effects of aerobic exercise by lactating women on breast-milk volume and composition. N Engl J Med 1994 Feb 17;330(7):449-53.
“In this study, aerobic exercise performed four or five times per week beginning six to eight weeks post partum had no adverse effect on lactation and significantly improved the cardiovascular fitness of the mothers.”

Prentice A. Should lactating women exercise? Nutr Rev. 1994 Oct;52(10):358-60.
“After 12 weeks, aerobic capacity was significantly higher in the women who had exercised than in the controls, but no differences in body weight, body fatness, energy expenditure, or resting metabolic rate (RMR) were noted. The exercise program had no effect on breast milk output or composition or infant weight gain. This demonstrates that recreational exercise sufficient to improve cardiovascular fitness without substantially altering energy balance does not adversely affect lactation performance.”

Wallace JP, Inbar G, Ernsthausen K. Infant acceptance of postexercise breast milk. Pediatrics. 1992 Jun;89(6 Pt 2):1245-7.
“Maximal exercise resulted in a significant increase in lactic acid concentration in breast milk that may be high enough to affect the taste of the milk. The decreased acceptance of postexercise milk was associated with increased lactic acid concentration.”

Wallace JP, Rabin J. The concentration of lactic acid in breast milk following maximal exercise. Int J Sports Med. 1991 Jun;12(3):328-31.
“Following maximal exercise, a significant increase in the concentration of lactic acid was found in the blood at 5 minutes postexercise and breast milk at 10 minutes postexercise. Although elevated, the lactic acid concentration of the 30-minute sample of breast milk was not significantly different from the resting sample. Maximal exercise can result in significant increase in lactic acid concentration in breast milk. Further research is needed to demonstrate whether the taste of the milk is affected.”

Lovelady CA, Lonnerdal B, Dewey KG. Lactation performance of exercising women. Am J Clin Nutr. 1990 Jul;52(1):103-9.
”Exercising women differed significantly from control subjects in maximum oxygen consumption, percent body fat, total energy expenditure, and energy intake. There was no difference between the groups in plasma hormones or milk energy, lipid, protein, or lactose content. Exercising subjects tended to have higher milk volume (839 vs 776 g/d) and energy output in milk (538 vs 494 kcal/d). Thus, there was no apparent adverse effect of vigorous exercise on lactation performance.”