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Home > Nutrition for Mom & Baby

Exercise and Breastfeeding

By Kelly Bonyata, IBCLC

• Does exercise affect milk supply or nutrient content?
• Does lactic acid increase in breastmilk after exercise?
• Will baby refuse the breast after mom exercises?
• Exercise guidelines for breastfeeding mothers
• Additional information
• Research

Does exercise affect milk supply or nutrient content?

No. Studies have shown no difference in the volume or composition of the milk 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 lactic acid increase in breastmilk after exercise?

Research has not shown a noticable 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).

Dr. Ruth Lawrence, in her most recent volume (Breastfeeding, A Guide for the Medical Profession, 1999 edition) says that there is no reason to wait to nurse after exercising.

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.

Page last modified: 08/07/2005
Written: 12/23/03

Additional information

• Exercise: Will it cause baby to refuse the breast? by Debbi Donovan, IBCLC
• Exercise: Does it cause a reduction in milk supply? by Debbi Donovan, IBCLC
• Strength Training for Moms by Colleen Kay Porter

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

Research

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.

Lovelady CA. The impact of energy restriction and exercise in lactating women. Adv Exp Med Biol. 2004;554:115-20.

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.

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."

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. 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."

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."

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."