PMS, or premenstrual syndrome, is a term familiar to the vast majority of women, and many have experienced it firsthand. It’s a common term of complaint, and even many men associate something with PMS—even if it’s just their own girlfriend’s bad mood. Nevertheless, most people don’t know what actually lies behind it or confuse it with other menstrual cycle symptoms. Yet female athletes and their coaches, in particular, should be aware of the causes and effects of premenstrual syndrome. This is because premenstrual syndrome affects athletic performance and must be taken into account not only during competitions but especially during training.
Premenstrual syndrome (PMS) refers to a group of physical and psychological symptoms that typically occur in the second half of the menstrual cycle after ovulation and subside with the onset of menstruation. Those affected often experience emotional symptoms such as irritability, mood swings, sadness, and restlessness, as well as physical symptoms such as breast tenderness, bloating, headaches, fatigue, or water retention. The primary cause is believed to be the interplay of hormonal fluctuations, particularly involving the hormones estrogen and progesterone (the so-called luteal hormone), as well as changes in brain metabolism, such as those involving the neurotransmitter serotonin. A significantly more severe and, above all, psychologically pronounced form is premenstrual dysphoric disorder (PMDD) (see below). Premenstrual dysphoric disorder must be distinguished from premenstrual syndrome. PMDD should be managed by a healthcare professional. PMS is not primarily a medical condition but rather the result of a functioning menstrual cycle. Not every woman who experiences a menstrual cycle also ovulates. Without a functioning cycle involving ovulation, there is no classic PMS, even though comparable symptoms may occur within the cycle.
The classic 28-day cycle and its phases
The classic 28-day cycle is divided into phases, although both the length of the cycle and the duration of the phases can vary from person to person. Cycle length varies from person to person and differs not only from woman to woman but can also vary from cycle to cycle; significant fluctuations may indicate (hormonal) imbalances. The 28-day cycle serves as a standardized and exemplary length; it begins on the first day of menstruation and ends one day before the onset of the next menstrual period.
Menstrual phase (Days 1–5, highly individual)
Shedding of the uterine lining. Menstruation occurs
Follicular phase (days 1–13, varies by individual and is more easily influenced)
Maturation of the egg in the ovary. Thickening of the endometrium due to the hormone estrogen. The hormones estrogen (estradiol), LH, and FSH (luteinizing and follicle-stimulating hormones) rise.
Ovulation (Days 14/13–15)
LH hormone reaches its peak and triggers ovulation. The egg is released. Estrogen, FSH, and testosterone also peak and then decline.
Luteal Phase (Days 15–28)
The empty follicle transforms into the corpus luteum. The corpus luteum produces progesterone, which rises sharply over time (luteal phase). This stabilizes the uterine lining and prepares the body for a possible pregnancy. If pregnancy does not occur, progesterone levels drop at the end of the cycle, leading to menstruation.
Luteal phase, ovulation, and PMS
During ovulation and the subsequent luteal phase, a clearly coordinated hormonal sequence takes place in the menstrual cycle. Ovulation is triggered by a sharp rise in the so-called luteinizing hormone (LH) (“luteinizing” comes from Latin and essentially means “forming or supporting the corpus luteum”). This so-called LH surge causes the mature follicle in the ovary to rupture and release the egg. The egg then travels into the fallopian tube, where it remains fertile for about 12 to 24 hours. The remaining follicle subsequently undergoes structural changes and becomes the so-called corpus luteum. This is precisely where the luteal phase begins. The corpus luteum now primarily produces progesterone as well as some estrogen. Progesterone is the dominant hormone of this phase. The role of progesterone is to stabilize the uterine lining previously built up by estrogen, improve its blood supply, and make it “receptive” for potential implantation. At the same time, progesterone regulates many processes throughout the body, including temperature, sleep, and the nervous system. Estrogen (and consequently testosterone, which is produced during estrogen synthesis) also rises slightly again toward the end of the luteal phase, as it is also produced by the corpus luteum and becomes functional in the event of pregnancy. However, the physical symptoms are mild and usually not noticeable. If pregnancy occurs, the early embryo produces a signaling hormone (hCG) that sustains the corpus luteum. As a result, progesterone production continues, and the endometrium remains stabilized. If pregnancy does not occur, however, the corpus luteum begins to degenerate after about 10 to 14 days. As a result, progesterone and estrogen levels drop again. This hormonal decline ultimately causes the uterine lining to detach and be shed. This leads to menstruation, and a new cycle begins.
Premenstrual syndrome occurs exclusively during the luteal phase and is, by definition, linked to an “ovulatory” cycle—that is, a cycle involving ovulation and the subsequent luteal phase: Only then does the typical hormonal sequence with a rise and fall in progesterone occur in the second half of the cycle, and only then is the condition classically referred to as PMS. If ovulation does not occur, this luteal phase is absent, and with it the typical progesterone dynamics. In such cases, similar symptoms may occur (e.g., mood swings, breast tenderness, or discomfort), but these are not medically classified as PMS, as they are not caused by progesterone; rather, they are viewed as nonspecific cycle-related or hormonal symptoms within the context of an anovulatory cycle (without ovulation).
Progesterone and Its Effects on Sports
Progesterone, the luteal hormone, prepares the body for a potential pregnancy after ovulation and maintains this preparation as long as pregnancy is possible. In addition, progesterone ensures that the uterine lining continues to thicken at a slower rate but is better supplied with blood and undergoes functional changes. At the same time, it has a “calming” and regulating effect throughout the body, as pregnancy is possible. It influences the immune and nervous systems, body temperature, and plays a role in sleep, mood, and stress management. Depending on individual characteristics, this can result in either positive or negative effects.
Since the embryo in a potential pregnancy contains foreign genetic material from the father, progesterone ensures that the immune system is modified so that it does not attack the foreign DNA. Although this altered effect occurs primarily in the placenta, it is evident to a greater or lesser extent throughout the entire body. This results in fewer pro-inflammatory signaling molecules (e.g., certain cytokines), more regulatory and calming immune messengers, and a reduced tendency toward strong cellular defense reactions. Autoimmune diseases and allergic reactions are sometimes dampened. Susceptibility to infection, on the other hand, may increase slightly. Of course, these effects depend particularly on progesterone levels and are most evident during pregnancy. However, the effects can also appear during the luteal phase with rising progesterone levels, albeit in a milder form. Intense training or competitions can lead to so-called leukopenia, which is often viewed as a weakening of the immune system. This is not correct, however, because the immune system does not actually become weaker. In this exercise-induced leukopenia, certain immune cells—leukocytes—migrate from the blood into deeper tissues such as bone marrow or the intestines, which increases susceptibility to infection, particularly in the respiratory tract, but strengthens the immune defense in the deeper tissues. The process is not yet fully understood from a medical perspective, but it plays a role in cycling practice. Female athletes need to take special care to protect themselves against respiratory illnesses.
Progesterone also acts on the brain. Among other things, it influences the GABA system (gamma-aminobutyric acid). GABA is the most important “inhibitory” neurotransmitter in the brain, reducing neuronal activity and thus having a calming effect. Allopregnanolone is produced in the brain, which has a calming effect and stabilizes the nervous system. At the same time, the serotonin system usually functions in a relatively balanced manner. Stress may be perceived as less burdensome. Biologically, this can be understood as the body’s attempt to prevent the woman from overexerting herself or exposing herself to dangers that could negatively impact a potential pregnancy. For some women, however, this also leads to persistent fatigue and drowsiness, which impairs athletic performance. If progesterone levels drop—and with them the calming effect—in the absence of pregnancy, this can lead to sudden discomfort accompanied by bouts of intense cravings. Especially toward the end of the luteal phase, care should be taken to maintain stable blood sugar levels.
In addition, progesterone acts directly on the brain’s temperature regulation center, the hypothalamus. There, it slightly raises the so-called “set point” for body temperature (by up to 0.5 degrees). The body begins to alter blood flow to the skin; through slight narrowing of blood vessels (mild vasoconstriction), heat loss decreases and more heat remains within the body. This can increase heat stress during exercise, which can become a problem especially in hot ambient temperatures. Conversely, this can have a positive effect in cold outdoor temperatures. During sleep, the core body temperature must be lowered for regeneration; therefore, it is important during the luteal phase to ensure a cool environment during nighttime sleep. Foods rich in energy and protein should generally be avoided in the last 2 hours before bedtime, as they further raise body temperature.
Although many research findings suggest that oxygen consumption, heart rate, and subjective perception of exertion during submaximal endurance exercise are not influenced by the menstrual cycle, several studies report higher cardiovascular stress during moderate exercise in the mid-luteal phase (MLP) when progesterone levels are at their peak. Resting heart rate was significantly higher during the MLP, with no significant differences between the other cycle phases. Nevertheless, some studies show no change in time to exhaustion at submaximal exercise intensity across the menstrual cycle. However, according to some scientists, the validity of these findings should be questioned due to the low reproducibility of the tests measuring time to exhaustion. During prolonged exercise in hot conditions, the mid-luteal phase—when body temperature is elevated—shows a reduction in the exercise time to exhaustion. Thus, due to the elevated body temperature and the potentially increased cardiovascular load, the mid-luteal phase has a potentially negative impact on performance during prolonged exercise and longer competitions.
Probably the most significant effect of progesterone is its influence on energy metabolism and energy availability. Unfortunately, there are very few studies in humans, as administering extreme doses of hormones or removing the uterus for research purposes is not justifiable. Progesterone is sometimes blamed for insulin resistance during pregnancy and may contribute to the onset of gestational diabetes. It is known that during the luteal phase, when progesterone levels are elevated, insulin-stimulated glucose uptake may be impaired. This impairs, for example, the replenishment of carbohydrate stores and recovery. At the same time, progesterone can also hinder glucose uptake induced by muscle contraction. It has recently been shown that glucose utilization in healthy women during exercise in the luteal phase is reduced compared to the follicular phase. The reason is obvious: protecting the potentially developing embryo with the best possible energy supply takes precedence over the muscles of the potential mother. Intense training sessions are therefore sometimes difficult to fuel and recovery is impaired. The focus of training should therefore be on sessions that utilize fat metabolism.
Distinction from Premenstrual Dysphoric Disorder (PMDD)
Premenstrual Dysphoric Disorder (PMDD) is a severe form of premenstrual syndrome. It also occurs during the second half of the menstrual cycle, but is primarily characterized by pronounced psychological symptoms that significantly interfere with daily life. Typical symptoms include, for example, severe concentration problems and mood swings, pronounced irritability or even anger, depressive moods ranging up to hopelessness, anxiety, or constant inner tension. Physical symptoms similar to those of PMS may also occur, but they are less prominent. Unlike “normal” premenstrual syndrome, the distress associated with PMDD is so severe that it can significantly limit relationships, work, or daily life. Another key factor for diagnosis is that the symptoms occur regularly in relation to the menstrual cycle and subside significantly or disappear after the onset of menstruation. The exact causes are not fully understood, but it is believed that some people are particularly sensitive to hormonal changes, especially in connection with neurotransmitters such as serotonin. In premenstrual dysphoric disorder, it is not assumed that there is simply “too little” serotonin, but rather that the brain reacts differently to serotonin, especially in the second half of the cycle. Premenstrual dysphoric disorder (PMDD) should be thoroughly evaluated by a doctor.
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