What is estrogen and progesterone?

What is estrogen and progesterone_.jpg


Estrogen is one of the primary female sex hormones. Its main role is to maintain the uterus lining and initiate ovulation.

Estrogen is low in phase 1. It rises in phase 2, where it reaches a peak just before ovulation. It dips slightly in phase 3 and then rises again, before falling in phase 4.

High estrogen

As estrogen travels in the blood, it can influence different parts of your physiology, not just your reproductive system. Some impacts of high estrogen may include increases in:

  • Joint laxity

  • Insulin sensitivity

  • Glycogen sparing

  • Release of serotonin

Joint laxity

When estrogen peaks in phase 2, it can increase joint laxity and alter neuromuscular control. This means that some joints (e.g. your knee) are slightly looser and the muscles surrounding them may not fire accordingly.

It is important to do a thorough warm-up before your sessions during this phase.

Insulin sensitivity

High estrogen in phase 2 can help to maintain blood sugar levels as it promotes insulin sensitivity. This means that your body is better at regulating blood sugar levels and adjusting for any imbalances.

This may lead to a slight decrease in your appetite.

Glycogen sparing

High estrogen at the end of phase 2 and in phase 3 causes your body to save glycogen stores in muscle and use fat instead when exercise is at a lower intensity.

As fat is a more efficient source of energy than glycogen, you may notice that you are able to complete longer endurance sessions at this time.


Estrogen also play a part in the release of serotonin – the “feel-good hormone”.

When estrogen peaks at the end of phase 2, more serotonin may be released. This can increase positivity and alertness.

Bone health

Estrogen also plays a role in the growth and development of our bones.


Progesterone is one of the primary female sex hormones. It is released from the ovaries and helps maintain the lining of the uterus.

Progesterone is low in phases 1 and 2 and then starts to ramp up in phase 3, where it reaches a peak, before dropping again in phase 4.

What to know in phase 3

As progesterone travels in the blood, it can affect your physiology in different ways. Some impacts of high progesterone may include increases in:

  • Body temperature

  • Muscle breakdown

  • Heart and breathing rate

  • Insulin resistance

Body temperature

High progesterone can elevate your core body temperature by 0.3-0.5 degrees Celsius. While this does not seem like much, you may feel hotter and sweat more during training and at night.

Try to keep on top of your hydration and check out my upcoming blog post on better sleep for some tips to build into your pre-bed routine.

Muscle breakdown

High progesterone can cause an increase in muscle breakdown, which makes it harder to maintain muscle mass and recover quickly.

Refueling with protein as soon as possible after your workout will help to repair and rebuild your muscles and enhance your recovery.

Heart and breathing rate

High progesterone can cause an increase in chemicals that affect your nervous system.

This process can cause your heart rate and breathing rate to increase, so don’t be concerned if you notice this happening.

Insulin resistance

High progesterone can also increase insulin resistance, which means that your blood sugar levels may be more unstable.

When your blood sugar levels dip, your appetite may increase and you are more likely to get cravings…topping up with healthy snacks during the day is a great way to maintain your energy levels and combat those chocolate cravings!

Having some protein at every meal will also help to keep your blood sugar levels stable.

This is an important reason why we need to monitor our menstrual cycle and ensure we have a regular cycle. We need to know these changes to ensure we have the best health for our bodies!