The question of exercising while breastfeeding is common for new mothers seeking to regain fitness and improve mental well-being. For the majority of healthy mothers, engaging in regular physical activity is safe and encouraged. Moderate exercise has not been shown to negatively affect a mother’s ability to nurse her child or influence the nutritional composition of her milk. Physical activity offers numerous benefits, including improved cardiovascular fitness, better mood, and reduced stress levels.
How Exercise Affects Milk Supply and Quality
A primary concern for nursing mothers is whether physical activity will diminish the volume of milk produced. Research consistently shows that moderate exercise does not reduce a mother’s overall milk supply, milk composition, or a baby’s growth rate, provided caloric needs are adequately met. The total quantity of milk is primarily regulated by the baby’s nursing demand and the mother’s endocrine system, not by physical exertion. However, a sudden, significant calorie deficit or dehydration can potentially impact milk volume, making proper fueling essential for the exercising mother.
Another common anxiety involves the potential for exercise to change the taste or quality of the milk due to lactic acid buildup. Lactic acid is a byproduct of intense anaerobic exercise, and it can temporarily increase in the bloodstream and, subsequently, in breast milk. Studies have found that this increase primarily occurs after maximal or exhaustive exercise, not after mild or moderate activity. When it does increase, the concentration of lactic acid in the milk usually returns to normal within 30 to 60 minutes after the exercise session ends.
While some babies may show a temporary preference against milk collected immediately following an exhaustive workout, this is not harmful. The taste threshold for lactic acid is higher than the concentration typically found in post-exercise milk, meaning the change in flavor is often subtle or undetectable by the baby. Furthermore, there is no evidence that breast milk containing elevated levels of lactic acid poses any health risk to the nursing child.
Practical Considerations for the Breastfeeding Athlete
Logistical planning is important for comfortably combining exercise with a nursing schedule. Many mothers find it helpful to breastfeed or express milk immediately before a workout. This practice alleviates the feeling of fullness or heaviness and reduces the risk of discomfort during activity. Finding a well-fitting, supportive sports bra is also important for comfort and to prevent excessive movement or compression of the breasts.
Proper fueling is necessary, as breastfeeding alone requires an estimated 450 to 500 extra calories per day. Exercise adds to this energy expenditure, meaning active nursing mothers require a total daily caloric intake between 2,300 and 2,800 calories to maintain their supply and energy levels. Mothers pursuing weight loss should aim for a gradual rate, not exceeding 1 pound (0.5 kg) per week, while maintaining a daily intake above 1,800 calories to protect milk volume.
Maintaining hydration is another consideration because fluid is lost through both sweating and milk production. While drinking extra water will not increase milk supply, dehydration can negatively affect energy levels and overall well-being. A general recommendation is to consume at least 3 liters of fluid daily, in addition to replacing the fluid lost during exercise. Keeping a water bottle accessible and taking frequent sips before, during, and after a workout is a simple strategy for staying adequately hydrated.
Resuming Fitness Postpartum
The return to fitness after childbirth must prioritize physical safety and gradual progression. Most healthcare providers recommend waiting until receiving clearance at the standard six-week postpartum check-up before beginning a structured exercise regimen. However, gentle activity like short, regular walks can often begin much sooner, provided the mother feels up to it.
The initial focus should be on low-impact activities to protect the recovering abdominal wall and pelvic floor muscles. High-impact movements such as running, jumping, or intense aerobics are not recommended until at least three to four months postpartum, and only after a thorough assessment of pelvic floor function. Specific exercises to rebuild core strength and tone the pelvic floor should be integrated early on, as these muscles provide foundational support compromised during pregnancy and delivery.
It is important to monitor the body for specific warning signs that indicate the exercise intensity is too high or unsafe. These signs include:
- Unusual pelvic pain.
- A feeling of heaviness or dragging in the vagina.
- Any loss of bladder control during or after the activity.
- Increased or renewed vaginal bleeding not related to the menstrual cycle.
If any of these symptoms occur, the mother should seek guidance from a doctor or a pelvic health physiotherapist before continuing her fitness routine.