When it starts and how long it lasts
It starts right after ovulation and ends on the first day of the next bleed. Around fourteen days is considered typical; Cleveland Clinic gives a normal range of about ten to seventeen days.
Unlike the first half of the cycle, it varies little from cycle to cycle. What makes a cycle long or short is usually decided before ovulation, not after.
What happens in the body
The follicle that released the egg becomes the yellow body – Latin corpus luteum, hence the name of the phase. It produces progesterone and oestrogen. Progesterone prepares the lining of the womb for a possible pregnancy; it thickens.
If there is no fertilisation, the corpus luteum shrinks, progesterone falls – and that drop starts the bleed. The symptoms reported during this time fall into this window: mood swings, breast tenderness, water retention, skin changes, changes in appetite.
Why this phase carries the cycle calculation
Because the luteal phase is fairly constant across cycles, calendar methods anchor ovulation from the end: fourteen days before the expected next period. Rhythmus does it this way, and so do the other period apps.
Training during this time
The evidence here is less clear than the tone of many posts suggests. The review by Hackney and colleagues puts the question into historical context and mainly shows how inconsistent the findings are. Anyone who derives fixed rules from it – lift heavy only in the first half, take it easy only in the second – goes beyond what the evidence supports.
We've written about this in detail in our article on the evidence for cycle-based training, including what it means for our own app.
The most common symptoms in detail
- Cravings before your period – where they come from and what helps
- Water retention – why the scales mislead you that week