Discussion
negative-distress, anxiety
PHYSIOLOGICAL STRESS
This paper aimed to fill the knowledge gap by exploring the relationship between hair cortisol levels, mental health outcomes and the effects of HIIT in pregnant women. By investigating the potential mechanisms underlying the protective effects of HIIT on mental well-being during pregnancy, we aim to provide evidence-based insights that can inform prenatal care strategies and improve the overall health and well-being of expectant mothers and their offspring. The most important finding of our study is that women attending HIIT intervention responded in a different direction in the production of cortisol compared to the EDU group performing standard moderate intensity physical activity. In the HIIT we observed the increase in the hair cortisol level (72.73% of women), and in the EDU group there was a substantial decrease (81.25%). The ITT analysis confirmed our findings. Thus, HIIT stimulated the production of cortisol, but it did not have a negative effect on the analyzed variables related to fear of childbirth and psychophysical condition during pregnancy. On the contrary, we observed a significant improvement in mental health only in the HIIT group. While cortisol is often referred to as a stress hormone, HIIT has been found to have a complex relationship with cortisol levels. One possible explanation for the increase in cortisol levels after HIIT among pregnant women is the physiological stress response triggered by the high-intensity nature of the exercise. HIIT involves pushing the body to its limits and can be physically demanding, which may activate the body’s stress response system and lead to cortisol release. Some studies suggest that acute bouts of HIIT can temporarily increase cortisol levels immediately after exercise (A study conducted by Jurgelaitiene et al. (This all suggest that pregnant women who participated in HIIT benefited from stress which is in accordance with current psychological models emphasizing that the stress response can be differentiated into both negative-distress and positive aspects-eustress. In the past two decades, there has been a growing interest in exploring the positive aspects of stress, coinciding with the emergence of positive psychology. This approach shifts the traditionally deficit-oriented focus of stress research toward highlighting positive human resources (The fear of childbirth and anxiety surrounding the labor and delivery process are widespread concerns among pregnant women, significantly influencing their overall well-being and birthing experience (To better understand the influence of intense training on women’s mental and physical health, it is important to acknowledge the limitations of this study and take necessary steps. Moreover, this study builds upon our previous work, where our focus was on examining alterations in psychological variables among a broader cohort of pregnant individuals who underwent HIIT (Worth exploring in further studies is the association between cortisol levels in women who trained HIIT during pregnancy and their psychological functioning postpartum. The question which researchers can try to answer in their future studies is whether increase in cortisol levels in HIIT participants during pregnancy can be recognized as ‘eustress’ type response that boost mental health of women postpartum. Another area worth further exploration is the relationship between cortisol levels and psychological variables among postpartum women who continue to participate in HIIT. It is worth to explore in a such approach whether cortisol levels stabilize or change in comparison to the levels during pregnancy and how this change relates to changes in psychological variables. Due to the fact that sleep pattern is one of the factors that significantly influences cortisol concentrations, in the future studies it is also worth to include specific tools to measure the amount and quality of sleep. Especially since sleep quality usually deteriorates as pregnancy progresses.