In professional rugby we watch for this closely, because a player who is training hard and going backwards is telling you something. The same applies to anyone who trains seriously alongside a demanding job.
Signs worth taking seriously
- Sessions that used to feel manageable now feel heavy, for weeks rather than days.
- Sleep that does not refresh you, or waking early and wired.
- Frequent colds, niggles or small injuries that keep returning.
- Lower motivation, a shorter fuse or a flatter mood than usual.
The places I look first
Fuelling. Training more while eating the same, or eating less to change body composition, can leave the body short of energy for both training and normal function. In sport this is called low energy availability, and it affects men as well as women.
Iron stores. Iron carries oxygen to working muscle. Stores can run low with heavy training, some diets or blood loss, and the effect on performance can appear before a full blood count changes. Ferritin, read alongside other markers, helps here.
Sleep and recovery. Adaptation happens between sessions. Short or broken sleep slows it down, and it is often the simplest place to make progress.
Training load. Hard sessions stacked without enough easy days can accumulate into fatigue that takes weeks to clear. Looking at the pattern of training over the last two to three months is usually revealing.
Thyroid and hormones. Thyroid function and, depending on the person, sex hormones can influence energy, recovery and body composition. These are interpreted alongside symptoms and the rest of the picture.
Recent illness. A viral illness can take longer to settle than people expect, especially if training resumed quickly.
How I approach it
History comes first: training, fuelling, sleep, work and recent illness. Then a targeted blood panel, taken at home, to check the areas that history points towards. Results are read together and turned into a short written plan, with a review to check what has changed.
When to see your GP straight away
Chest pain, fainting, palpitations, breathlessness out of proportion to effort, or unexplained weight loss need prompt assessment by your GP or NHS 111, or 999 in an emergency. Please do not wait for a performance review.
