The Class We Missed

The menstrual cycle

How the cycle works, and what it does to energy, mood, sleep, appetite and workouts. Plus PMS, and how to track a cycle.

About 25 min · 0 of 7 done

  1. 1How the cycle worksA cycle is counted from the first day of one period to the first day of the next. In each cycle the body builds up the uterine lining, releases an egg, and sheds the lining if there's no pregnancy.4 min
  2. 2The hormones, step by stepEstrogen rises in the first half of the cycle and builds the uterine lining. A surge of LH triggers ovulation. Progesterone rises after ovulation. When estrogen and progesterone both drop, a period starts.3 min
  3. 3What the cycle does to the bodyCramps come from prostaglandins, chemicals that make the uterus contract. Headaches, bloating, breast tenderness, skin changes, discharge and body temperature each have their own cause, and some aren't fully understood yet.7 min
  4. 4Why mood, appetite and sleep shiftMood changes before a period follow hormone shifts, and PMS and PMDD are real medical conditions. On average, people eat about 168 more calories a day after ovulation. Sleep changes are small.3 min
  5. 5What's normal, and when to get helpRegular cycles last 21 to 35 days, and periods last up to 7 days. Tracking shows a person's own pattern. See a doctor if periods stop, the cycle or bleeding changes a lot, or bleeding is very heavy.5 min
  6. 6Should training follow the cycle phase?Reviews haven't found one best phase to train in. Dr. Stacy Sims, who promoted phase-based training, now recommends training by how ready the body feels, lifting consistently all month and fueling every day.4 min
  7. 7Fuel, data and moving through symptomsEating enough every day matters in every phase, and a missing period can be a sign of underfueling. One watch reading can't tell a sleep effect from a cycle effect. Regular exercise eases period pain.3 min
  8. QuizA short quiz on this section. Try again for new questions.4 questions

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