What does it mean when the menstrual cycle changes?
The female "vital sign" for physiology and performance
Team! Happy April! Last month we learned about the normal menstrual cycle and why being tuned in to your cycle matters. This month we will take a look at what it means when menstrual cycles changes. Feel free to leave comments, ask questions and by all means, message me if something isn't clear. We're all learning together! Enjoy! -Carla
The human endocrine system is a complex network of “hormonal conversations” between various organ systems of the body that promote everyday functioning as well as responding to changes within the body and the environment.
Because reproduction is critical for the survival of the species, the menstrual cycle is front and center in these hormonal conversations. When the body or the external environment changes in an unfavorable way, the endocrine system protects the female from becoming pregnant during unfavorable conditions that could harm the mother or her offspring.
The physiologic changes and adaptations of pregnancy are profound, as we learned in my first post, “What is Women’s Performance Endocrinology?”. So when the endocrine system detects conditions that could limit the ability to physically adapt to the conditions of pregnancy (thus potentially putting the mother and offspring in danger) the endocrine system “turns off” the menstrual cycle until conditions become more favorable.
The endocrine system “sees” physical performance in sport or occupation in a similar way to pregnancy. If conditions are not optimal for physical performance (ie physical stress and adaptations of pregnancy), the menstrual cycle will turn off, until conditions are more favorable for optimal physical performance.
This eloquent, evolutionarily conserved mechanism provides us with a tool that signals when the body is primed for performance versus when a physical or environmental stressor is keeping us from performing at our best.
Causes of abnormal or absent menstrual cycles
The list of circumstances where menstrual cycles may become irregular is long and beyond the scope of this post. However, below, is a list of the most common reasons why a woman’s menstrual cycle may become irregular or absent.
Thyroid dysfunction: Hypo-thyroidism (under-production of thyroid hormone by the thyroid gland), Hyper-thyroidism (over-production of thyroid hormone by the thyroid gland)
PCOS (Polycystic Ovarian Syndrome): A condition that results in absent or irregular menstrual cycles due to an imbalance of the production of androgens (male hormones) by the ovaries and adrenal glands.
Hyperprolactinemia: Over-production of the hormone Prolactin by the pituitary gland can cause irregular menstrual cycles.
Energy imbalance - Low Energy Availability (LEA)
Overtraining / Underfueling - This is, by far, the most common issue that I see in my clients of all ages and of all fitness levels. The body’s energy expenditure does not match the body’s perception of the availability of fuel. This goes beyond calories in/calories out - other equally important variables include nutrient timing and availability of macronutrients (carbohydrates, protein, and fat) during training, recovery, and times of high stress.
Disordered eating - Mental health disorders and dysfunctional relationships with food that exist on a spectrum of mild to severe. Examples include anorexia and bulimia.
Exists on a spectrum of mild to severe: Life stress, grief, loss, divorce, dysfunctional interpersonal relationships, and a geographical move, among other causes.
Chemotherapy/radiation for cancer treatment or medical treatment of other conditions.
Surgical or medical treatment involving the ovaries, uterus, and pituitary gland.
Head injury or malignancy
As we learned previously, the pituitary gland drives the hormonal “messaging” of the menstrual cycle. Processes that disrupt the function of the pituitary gland, such as head injury or tumor/malignancy, can cause menstrual cycle irregularity.
If you are of reproductive age (age 12-45) and you miss your period, the FIRST thing you need to do is take a pregnancy test!
Perimenopause / Menopause
The transition to menopause (perimenopause) typically begins in the mid-40s and concludes with menopause, on average, by age 52 in the US. During perimenopause, menstrual cycles become irregular and less frequent until cycling stops. One year beyond the final menstrual cycle is when menopause is achieved.
This transition can occur much earlier in some women who have medical conditions or other unknown factors that lead to this transition occurring at a younger age. Premature menopause is defined as achieving menopause before the age of 40.
If you are experiencing irregular menstrual cycles, it is important to connect with your healthcare provider AND your coaches, trainers and nutritionists. As you can see from the long list of circumstances above, the causes of abnormal menstrual cycles span multiple disciplines including medical, physical performance, nutrition, and wellness. A multi-disciplinary approach is required to address the complexity of the factors impacting female reproductive physiology.
Bringing it Back to Evolution
As I just mentioned, the most common situations I see as an endocrinologist specializing in female performance (this includes athletes, police, military, paramedics, firefighters, CEOs, and executives among others) is the impact of low energy availability (LEA) and psychological stress on the menstrual cycle, performance, and overall physiology.
LEA and psychological stress illustrate the interplay between the endocrine pathways of the “fight or flight” (a.k.a the sympathetic nervous system (SNS)) response, the menstrual cycle, and overall female physiology. These interactions are part of a powerful endocrine force that is highly conserved through evolution that promotes survival from reproductive age through menopause and beyond.
Next month we will improve our understanding of this powerful endocrine interplay so that we can harness this system to our performance advantage through every stage of reproductive life. Stay tuned!
Note: For the purposes of this article, the terms “Woman”, “Mother” and “Female” refer to individuals who possess two X chromosomes.
I had the privilege of being a guest on two amazing podcast episodes that dropped this past week. Enjoy!
Inside Sports Nutrition Podcast: Hormones and Female Physiology with Dr. Carla DiGirolamo - Ep. #69 – Dina Griffin/Bob Seebohar
Fit Womens Weekly Podcast: Should Workouts Change As You Get Older? Dr. Carla DiGirolamo Breaks It All Down - Kindal Boyle