How the menstrual cycle shapes your life
The menstrual cycle is a natural, physiological process that significantly affects various aspects of a woman's body and mind. It has long been associated with mood swings, changes in energy levels and fluctuations in physical performance. However, emerging research in neuroscience, psychology and female biology shows that the menstrual cycle can influence much more than just physical symptoms - it can also impact decision-making, cognitive function and fitness performance. This article explores the science behind how the menstrual cycle affects these factors, based on the latest research and data.
The menstrual cycle typically lasts 28 days, although it can range from 21 to 35 days. It is divided into four main phases: the menstrual phase, the follicular phase, the ovulatory phase and the luteal phase. Each of these phases is governed by fluctuations in sex hormones, particularly oestrogen and progesterone, which influence various systems in the body.
Menstrual phase (Days 1-5): This is the phase when bleeding occurs, and the body sheds the uterine lining. Hormone levels are low, and women may experience fatigue and discomfort.
Follicular phase (Days 6-14): Following menstruation, oestrogen levels rise, promoting the growth of ovarian follicles. This phase is typically characterised by increased energy and optimism.
Ovulatory phase (Day 14): Ovulation occurs when an egg is released from the ovary. This is when women are most fertile and may experience heightened libido and peak physical energy.
Luteal phase (Days 15-28): After ovulation, progesterone rises to prepare the body for a potential pregnancy. If fertilisation does not occur, progesterone levels drop and menstruation begins. This phase is often associated with PMS symptoms such as mood swings, irritability and fatigue.
Menstrual Cycle and Decision-Making
Decision-making is a complex process involving both cognitive and emotional factors. Research suggests that fluctuations in hormones throughout the menstrual cycle can influence how women make decisions, particularly in areas like risk-taking, social interactions and cognitive biases.
Risk-taking: A study by Koch (2008) found that women in the ovulatory phase, when oestrogen levels are highest, tend to take more risks than those in the follicular or luteal phases. The researchers hypothesised that this could be related to the increased confidence and motivation that accompanies higher oestrogen levels. This effect may have evolutionary significance, as women may have been more likely to take risks during their most fertile phase.
Social decisions: In the context of social decision-making, research shows that women in the follicular phase are more likely to favour cooperation and engage in positive social interactions. The elevated levels of oestrogen during this phase promote feelings of trust and empathy. Conversely, during the luteal phase, higher progesterone levels are associated with a more defensive and competitive attitude.
Cognitive biases: Hormonal fluctuations can also affect cognitive biases, such as the tendency to overestimate the likelihood of negative outcomes (known as the loss aversion bias). Research has shown that women in the luteal phase may experience a greater tendency to focus on negative consequences, which could influence decision-making in uncertain situations.
Menstrual Cycle and Fitness Performance
Fitness and physical performance are also affected by hormonal fluctuations during the menstrual cycle. Studies have shown that women’s strength, endurance and cardiovascular performance can vary depending on the phase of their cycle.
Strength and power: A study published in the Journal of Strength and Conditioning Research (2017) examined the impact of the menstrual cycle on strength performance. The researchers found that women generally experience better strength gains during the follicular phase, likely due to the higher levels of oestrogen, which promotes muscle growth and repair. In contrast, during the luteal phase, progesterone levels increase, which may lead to a decrease in strength and performance.
Endurance and aerobic performance: Aerobic performance, including endurance activities like running or cycling, is also influenced by the menstrual cycle. Research suggests that women perform better in endurance activities during the follicular phase, when oestrogen is higher, as it improves fat oxidation and energy utilisation. The luteal phase, with its elevated progesterone levels, may lead to a decrease in endurance due to a higher perceived rate of exertion and altered metabolic responses.
Body temperature and exercise: Core body temperature fluctuates during the menstrual cycle, which can also impact exercise performance. During the luteal phase, body temperature is slightly elevated, which can lead to increased perceived exertion and discomfort during exercise. This may explain why some women report feeling less motivated or fatigued during this phase.
The Psychological and Emotional Impact of the Menstrual Cycle
The menstrual cycle can have significant psychological and emotional effects. These effects are largely attributed to changes in hormone levels, particularly oestrogen and progesterone, which can influence neurotransmitter systems in the brain.
Mood swings and PMS: Many women experience mood swings, irritability and anxiety during the luteal phase, a phenomenon often referred to as premenstrual syndrome (PMS). The exact causes of PMS are not fully understood, but it is believed to be linked to the drop in oestrogen and rise in progesterone during the luteal phase. These hormonal shifts can affect serotonin levels, a neurotransmitter that regulates mood. Low serotonin levels have been associated with symptoms such as depression and anxiety.
Cognitive function: Cognitive performance can also be affected by the menstrual cycle. Research suggests that women tend to have better verbal memory and cognitive function during the follicular phase, when oestrogen is higher. In contrast, the luteal phase may be associated with impairments in working memory and attention, possibly due to the sedative effects of progesterone.
Stress response: The menstrual cycle also influences how women respond to stress. During the follicular phase, women tend to have a more robust stress response, with increased cortisol production in reaction to acute stress. In the luteal phase, however, women may have a reduced stress response, which could be linked to the sedative effects of progesterone.
Statistical Insights and Data
Several studies have provided quantitative insights into the impact of the menstrual cycle on decision-making, fitness, and emotional well-being. For example:
A 2018 study published in Frontiers in Psychology showed that women in the follicular phase scored higher in tests measuring cognitive performance (such as verbal fluency and problem-solving tasks) compared to women in the luteal phase.
A survey conducted by Sibille (2019) found that 60% of women reported experiencing significant changes in their physical performance during the menstrual cycle, with 38% noting reduced endurance and strength during the luteal phase.
A study on risk-taking behaviour (Koch, 2008) found that women were more likely to engage in high-risk activities during ovulation, with an increase in gambling behaviour and impulsive decisions during the high-oestrogen phase.
The menstrual cycle is a powerful force that influences many aspects of a woman's life, from physical performance to decision-making and emotional well-being. The hormonal fluctuations that occur during the cycle - particularly in oestrogen and progesterone - affect brain function, metabolism and physical capacity in distinct ways across the different phases. While individual experiences vary, understanding these hormonal influences can help women optimise their decision-making, fitness routines, and emotional health throughout the cycle. Awareness of these physiological patterns can also provide valuable insights for tailoring lifestyle choices to maximise overall well-being.
As research continues to uncover the complexities of the menstrual cycle, it is becoming increasingly clear that this natural process is not just about reproduction - it is a key factor in shaping women's lives in profound and scientifically measurable ways.
