What is Progesterone & why is it important for athletes?

What Is Progesterone?

Progesterone is a key reproductive hormone in women, primarily produced after ovulation during the second half of the menstrual cycle (luteal phase). It plays a vital role in regulating menstrual health, supporting fertility, and balancing oestrogen.

For female athletes, progesterone is also a marker of hormonal resilience, energy balance, and recovery. Persistently low levels can indicate disrupted cycles, under-fuelling, or the early signs of Relative Energy Deficiency in Sport (RED-S).

"Progesterone is essential for a healthy menstrual cycle, recovery, and bone protection. In female athletes, low levels can be an early sign of Relative Energy Deficiency in Sport (RED-S), where energy demands exceed intake. This can impair performance, recovery and increase injury risk. I recommend testing around day 21 of a typical 28-day cycle to confirm ovulation and assess hormonal health. Pair it with oestradiol, LH and FSH to identify signs of hormonal disruption linked to under-fuelling or high training loads."

Dr Thom Phillips

How Progesterone Supports Performance

1. Cycle Health & Ovulation

   Progesterone confirms that ovulation has occurred. Without ovulation, periods may become irregular or disappear, often an early sign of energy imbalance or excessive training load.

2. Recovery & Sleep

   Progesterone promotes calm, restorative sleep and supports parasympathetic nervous system activity, critical for recovery and adaptation.

3. Mood & Cognitive Focus

   It plays a role in mood stability and mental sharpness, especially in the luteal phase. Low levels can lead to anxiety, irritability, or brain fog.

4. Fertility Planning

   For athletes trying to conceive, progesterone testing confirms ovulation and luteal phase adequacy — both essential for natural fertility.

What Causes Low Progesterone in Athletes?

• Low energy availability / under-fuelling

• Overtraining or high-volume endurance work

• Very low body fat levels

• Chronic stress or disrupted sleep

• Coming off hormonal contraception (temporary suppression)

• Polycystic Ovary Syndrome (PCOS)

Symptoms of Low Progesterone in Athletes

• Irregular or missed periods, especially during intense training blocks

• Heightened anxiety, poor sleep quality, or difficulty winding down post-training

• Pronounced premenstrual symptoms – including headaches, mood swings, and bloating – that disrupt performance or focus

• Signs of hormonal disruption that may affect recovery, adaptation, or fertility

• Early indicators of Relative Energy Deficiency in Sport (RED-S), including low energy availability and hormonal imbalance

Why Test Progesterone?

• To confirm ovulation in natural menstrual cycles

• When periods are irregular, light, or absent

• To support fertility tracking or menstrual health planning

• As part of a RED-S or hormone imbalance screen

• In athletes transitioning off hormonal contraception

Note: For accuracy, progesterone should be tested 5–7 days after ovulation (usually day 21 of a 28-day cycle).

How to Support Healthy Progesterone Levels

• Ensure adequate energy and fat intake to support hormone production

• Reduce high-volume training or add deload phases when needed

• Manage stress through sleep, mindfulness, and recovery

• Prioritise ovulatory health by supporting overall cycle regularity

In Summary

• Progesterone confirms ovulation and supports menstrual, mental, and metabolic health

• Low levels may signal hormonal suppression, under-fuelling, or RED-S

• Key for tracking cycle health, recovery, and fertility

• Should be tested at the correct phase of the cycle for accurate insight

Track your progesterone to protect long-term health, unlock peak performance, and understand your cycle, not just your symptoms.