Can exercise affect the quality of breast milk? Amid several online myths surrounding this topic, researchers have uncovered new evidence that suggests that breast milk becomes particularly beneficial for babies when mothers engage in high-intensity exercise.

Researchers from the Norwegian University of Science and Technology (NTNU) discovered that intense workouts boost the levels of the adiponectin hormone in breast milk that protects babies against diabetes and helps regulate their metabolism.

"There are so many myths about exercise and breast milk. We simply need to know more. The primary aim of our research is to find out if we can limit the development of overweight in children," Trine Moholdt, an NTNU researcher who led the study, said in a news release.

The researchers collected 240 samples of breast milk from 20 new mothers. The samples were taken both before and at specific intervals after two exercise sessions and they were compared against those taken at the same intervals after periods of inactivity.

The results showed that mothers who completed high-intensity interval training had higher levels of adiponectin in their breast milk after their exercise session compared to those who were sedentary. However, with moderate levels of exercise, there was no significant impact on adiponectin levels.

Adiponectin is a protein hormone that plays a crucial role in regulating glucose levels, lipid metabolism, and insulin sensitivity. Earlier studies have shown that a relatively high content of adiponectin in breast milk may prevent rapid weight gain in infancy, while low levels are linked to insulin resistance and Type 2 diabetes.

"The hormone is secreted from fatty tissue and enters the bloodstream, and much of what is in the blood goes into the milk. We were not that surprised by the findings, but now we know for certain," Moholdt said.

However, the study results showed that the composition of breast milk varies between mothers who have high and low body mass indexes, and these differences in breast milk composition can play a role in the transfer of obesity from mother to child.

"Intense exercise led to a higher response. In my opinion, new mothers don't have to worry about lactic acid in their breast milk. There is no research suggesting that this is bad for babies, and lactic acid is energy-rich," Moholdt added.