Iron and the Absorption Week: Why the Quiet Weeks Are Training Too
Female Physiology
Iron, Fatigue & Your Quieter Training Week
If an easier week does not leave you feeling fresher, low iron may be worth investigating.
After a demanding training block, an easier week gives your body time to absorb the work. The volume drops, the sessions feel gentler and, after a few days, you may expect your legs and energy to begin bouncing back.
But what if they do not?
Feeling tired during a heavy training block is normal. Feeling unusually flat, heavy or breathless when your training has eased may be a sign that something else needs attention. One possibility for female endurance athletes is low iron.
Why iron matters
Iron helps carry oxygen around your body and supports energy production. When your iron stores are low, running can feel harder than it should. You may still be able to complete your sessions, but recovery and performance can begin to suffer.
Female athletes can be particularly vulnerable because iron is lost through menstruation, especially with heavy periods. Endurance training can add to the demand, while under-fuelling or eating little iron-rich food can make it more difficult to replace what is being lost.
In one study of university athletes, almost half of the female athletes tested had low iron stores despite none being classified as anaemic. This is important because iron can become low before standard signs of anaemia appear.
An easier week can reveal the difference between normal training fatigue and tiredness that may need further investigation.
Signs worth paying attention to
Low iron can look different for everyone, but possible signs include:
- Fatigue that feels greater than your training load would explain
- Heavy legs or a noticeable drop in performance
- Becoming unusually breathless during familiar sessions
- Difficulty recovering between sessions
- Feeling weak, light-headed or unable to concentrate
- Regularly feeling cold
- Heavy menstrual bleeding
These symptoms can have many causes, so they do not automatically mean your iron is low. The only way to understand what is happening is through an appropriate blood test interpreted by a health professional.
Use the quiet week to check in
Your easier week is not lost training. It is when your body repairs, adapts and prepares for the next block. It is also a useful opportunity to notice whether your energy begins to return as the load comes down.
Ask yourself:
- Does my fatigue match the training I have completed?
- Am I beginning to feel better as the week progresses?
- Have my periods recently become heavier?
- Am I eating enough to support my training?
- When did I last have my iron levels checked?
What you can do
If persistent fatigue or heavy periods are part of your experience:
- Speak with your GP or sports dietitian about whether a blood test is appropriate.
- Include iron-rich foods regularly, such as red meat, seafood, eggs, legumes, tofu, leafy greens and iron-fortified foods.
- Pair plant-based iron sources with vitamin C-rich foods to support absorption.
- Avoid starting iron supplements without professional advice. Too much iron can also be harmful.
This week’s takeaway
If your energy begins to return as your training eases, your body may simply be absorbing the previous block. If the fatigue remains unusually strong or continues across several weeks, do not assume you need to train harder. It may be time to check what is happening underneath.
Sources: Nabeyama et al. (2023), PMID 38018828. Pedlar et al. (2018), PMID 29280410. Alfaro-Magallanes et al. (2020), PMID 33348847.
This information is general in nature and is not a substitute for individual medical or nutrition advice.
