Pre-Season Blood Tests for Triathletes, Runners and Cyclists in Pembrokeshire

1 day ago

3 min read

Pembrokeshire is home to some of the toughest triathlons, sportives and trail races in the UK. Hard training puts real demands on your body, and a blood test gives you a clear picture of how it is coping. The end of the racing season and the start of winter training are two of the most useful times to test.

When is the best time to test?

At the end of the season. A long season of racing can leave iron stores, vitamin D and other markers lower than you might expect. Testing now shows how your body has coped.
Before your winter or pre-season build. A baseline gives you and your GP something to compare against as training load increases, and lets you fix common deficiencies before they hold you back.
During the season, if something feels wrong. Unexplained tiredness, poor recovery or a sudden drop in performance are all good reasons to check.

Testing at the same point each year, and in similar conditions, makes it much easier to spot real changes over time.

Markers that matter for endurance athletes

Ferritin and iron. Ferritin shows how much iron your body has in store. Low iron is common in endurance athletes, particularly women, runners and anyone who eats little red meat. It can cause tiredness, breathlessness and poor recovery even before anaemia develops.
Full blood count. Checks haemoglobin and red blood cells, which carry oxygen to working muscles, as well as white blood cells, which can be affected by heavy training and frequent illness.
Vitamin D. Important for bone and muscle health. In the UK, sunlight between October and March isn't strong enough for most people to make enough, so levels often fall over the winter training months.
Hormones. Training hard without eating enough to fuel it can lower hormone levels in both men and women. This is known as relative energy deficiency in sport (RED-S), and is linked to fatigue, stress fractures and, in women, irregular or missed periods.
Muscle markers such as creatine kinase (CK). These rise after hard or long sessions, so results need interpreting alongside your recent training.
Thyroid, kidney, liver and inflammation markers, for a picture of your general health and to rule out other causes of tiredness.

The exact markers depend on the test you choose, so check the test page for the full list.

Signs it may be worth getting checked

Feeling tired all the time, even with enough rest
Performance dropping despite consistent training
Slow recovery or heavy legs between sessions
Picking up colds and infections often
Recurring injuries or stress fractures
Irregular or missed periods
Poor sleep, low mood or loss of motivation

When not to wait for a blood test. Stop exercising and get medical advice promptly if you have chest pain, palpitations, fainting or unusual breathlessness during exercise. Call 999 if symptoms are severe.

How to prepare for your test

Avoid very hard or long training for 24 to 48 hours beforehand, as intense exercise can temporarily raise some markers.
Book a morning appointment if you can, especially for hormone tests.
Drink plenty of water beforehand, which makes the blood draw easier.
Some tests need you to fast. Check the test page, or ask us when you book.
Tell us about any supplements you take. Iron and high-dose biotin can both affect results.
Hormone results vary through the menstrual cycle, so let us know where you are in your cycle when you book.

After your results

Every result is reviewed by one of our GPs, and you receive a letter explaining what it means through our patient portal. If something needs attention, we can suggest changes to diet or training, a repeat test, or a follow-up appointment with the same team. Testing again later in the season shows whether those changes are working.

The EveryAthlete health check

Our EveryAthlete health check measures more than 80 data points covering nutrition, muscle, joint and hormonal health, with specific tests for sports nutrition and muscle health. Men can add a PSA test when booking.