How does exercise decrease dysmenorrhea (painful menstruation) and menstrual flow?

How Exercise Decreases Period Pain and Flow

Exercise reduces menstrual pain and flow through multiple physiological mechanisms including improved blood circulation, hormonal regulation, and endorphin release that collectively reduce uterine contractions and inflammation.

Physiological Mechanisms of Exercise on Menstrual Symptoms

Blood Flow and Circulation Effects

• Exercise increases blood circulation throughout the body, including the pelvic region
• Improved blood flow reduces ischemia (restricted blood flow) in the uterine muscles
• Better circulation helps remove prostaglandins, which are inflammatory compounds that cause uterine contractions and pain 1
• Enhanced circulation prevents blood pooling in the pelvic area, potentially reducing heavy menstrual flow

Hormonal Regulation

• Regular exercise helps balance reproductive hormones that influence menstruation
• Exercise can modulate the hypothalamic-pituitary-ovarian axis, affecting the release of gonadotropin-releasing hormone (GnRH) 2
• This hormonal modulation may reduce excessive endometrial buildup, resulting in decreased menstrual flow
• Exercise influences levels of estrogen and progesterone, which control endometrial thickness and shedding patterns

Endorphin Release and Pain Modulation

• Exercise stimulates the release of endorphins, the body's natural pain relievers 3
• These endorphins activate opioid receptors in the central nervous system, reducing pain perception
• The analgesic effect can last beyond the exercise session itself, providing ongoing pain relief
• Exercise-induced analgesia works through both central nervous system pathways and peripheral mechanisms 3

Stress Reduction and Autonomic Balance

• Exercise reduces stress hormones like cortisol that can exacerbate menstrual symptoms
• Lower stress levels improve autonomic nervous system balance 4
• Enhanced parasympathetic activity promotes relaxation of smooth muscle, potentially reducing painful uterine contractions
• Improved autonomic function helps regulate blood vessel constriction and dilation, affecting menstrual flow

Evidence for Exercise Benefits on Menstrual Symptoms

The Cochrane review on exercise for dysmenorrhea found that:

• Regular exercise (45-60 minutes, three times weekly) may provide clinically significant reduction in menstrual pain intensity by approximately 25mm on a 100mm visual analog scale 1
• Both low-intensity exercise (stretching, yoga) and high-intensity exercise (aerobic training) showed benefits for reducing menstrual pain 1

Exercise Recommendations for Menstrual Symptom Relief

Types of Effective Exercise

• Low-impact aerobic activities (walking, swimming, cycling)
• Yoga and stretching, particularly poses that target the pelvic region
• Core strengthening exercises that improve abdominal and lower back support
• Regular exercise throughout the month, not just during menstruation

Timing and Frequency

• Exercise regularly throughout the menstrual cycle for best results
• Some women benefit from continuing exercise during menstruation, while others may need to reduce intensity
• Consistency is key - benefits are most pronounced with regular exercise routines
• At least 3 sessions per week of 45-60 minutes appears most effective 1

Cautions and Considerations

• Excessive high-intensity exercise can potentially disrupt menstrual cycles in some women, leading to amenorrhea or luteal phase defects 4, 5
• This is more common in athletes with very low body fat or energy deficiency (RED-S) 4
• Women with severe dysmenorrhea should start with low to moderate intensity exercise
• Hydration is particularly important when exercising during menstruation to prevent dehydration

Exercise represents a safe, non-pharmacological approach to managing menstrual symptoms that has additional health benefits beyond menstrual pain relief. The evidence suggests that regular, moderate exercise throughout the month is most effective for reducing both menstrual pain and flow.