Unless you are taking hormonal contraception (the pill), your hormones change during your menstrual cycle.
These hormonal variations can affect your fitness and general physical performance.
Doctors divide the menstrual cycle into two different hormonal phases:
- The first phase is from day one to 14. Days 1 to 7 are usually the period itself. This is called the
follicular phase and is marked by relatively low levels of oestrogen, except for an increase on about day
14 when ovulation takes place
- The second phase of the cycle, from day 15 to 28 (of an average 28-day cycle) is called the luteal phase,
and is characterised by moderately high and stable levels of oestrogen
Oestrogen is an important hormone affecting not only your cycle, but also the type of fuel available for your
working muscles. When you are in the follicular phase of your cycle and have low levels of oestrogen, high levels
of physical activity will break down muscle glycogen (your quick energy stores) for fuel. During the luteal phase,
when oestrogen levels are higher and more fat than muscle glycogen is burned, you have lower lactic acid levels and
spare glycogen when you work out.
Using your cycle to your benefit
During the follicular phase, your body rapidly breaks down carbohydrates for speed and efficiency, and your body
is primed for providing energy for intense exercise. During this phase, your training schedule will benefit from high
intensity exercise because you will be accessing quick energy through carbohydrates.
During the luteal phase, however, your body is mainly using fat. Because fat is a source of slower, more sustained
energy than carbohydrate, your intensity of exercise may suffer during this phase. Endurance exercise will feel easier,
and you may need less recovery time because you are increasing fat breakdown.
If you do regular high intensity training, you are likely to find that during your follicular phase (day 1-14) you’ll
feel great. You seem to have more energy and vitality during your sessions, and feel as though you’re really progressing.
The same day the following week may find you in the luteal phase, and you may feel sluggish and lethargic, and you
struggle to reach your training goals.
Your body’s monthly hormonal changes do not mean that you should restrict your schedule to only one type of
training per phase of your cycle. It just means that you’ll feel different after each type of workout depending
on what stage of your cycle you’re in.