Best Blood Test for Sports Performance (UK)

Training is only as effective as your recovery, and recovery depends on your underlying biochemistry. A sports-focused blood test surfaces the markers that drive (or limit) athletic performance: iron, hormones, inflammation, recovery indicators and nutrient status. This guide explains what to test and which Chxhealth panels are designed for athletes.

Markers that matter for athletes

Iron status (ferritin, transferrin saturation): Endurance athletes are prone to low iron from foot strike haemolysis, GI losses and high turnover. Low iron silently caps performance.

Vitamin D: Linked to muscle function, immunity and recovery. UK athletes are particularly prone to deficiency in winter.

Hormones (testosterone, cortisol): Chronic overtraining suppresses testosterone and raises cortisol. The ratio between them is a useful overtraining marker.

Thyroid function (TSH, free T4, free T3): Low energy availability and overtraining can suppress thyroid output (low T3 syndrome).

Inflammation (hs-CRP): Persistent inflammation suggests inadequate recovery or underlying issues.

Full blood count: Overall haematology including haemoglobin (oxygen delivery).

Liver and kidney function: Especially relevant if you supplement or use NSAIDs regularly.

B12 and folate: Underpin red cell production and energy metabolism.

Testing tips for athletes

Avoid all strenuous exercise for 48 hours before testing. Hard training transiently raises CK, AST, ALT and inflammation markers, and can mimic disease patterns.

Test fasted (10 to 12 hours, water only) for accurate lipid and metabolic markers.

Standardise the conditions: same time of day, same point in training cycle, ideally during a deload or rest week.

Hydrate well the day before testing for accurate haematology readings.

Best Chxhealth panels for this

The Chxhealth panels below are designed for the markers discussed above. Each comes with a plain English PDF report, lab analysis by Randox (UKAS, ISO 15189), and the phlebotomy fee included in the price.

Related biomarker guides

Read more about the specific markers discussed in this guide:

• Ferritin
• Iron
• Haemoglobin
• Testosterone
• Cortisol
• TSH
• Free T3
• CRP (C-Reactive Protein)
• Vitamin D
• Vitamin B12

FAQs

Can I test the day after a hard training session?

It is better to wait at least 48 hours. Hard training transiently elevates liver enzymes, CK, inflammation markers and cortisol, which can produce a misleading picture.

Why are athletes prone to low ferritin?

Endurance running causes foot strike haemolysis (red cells damaged in feet), and high training volumes increase iron turnover. Female athletes are at additional risk due to menstrual losses. Read more in our ferritin glossary entry.

What is the testosterone to cortisol ratio?

An indirect marker of training stress and recovery. A persistently falling ratio over weeks can signal overtraining or insufficient recovery. Not a single-time-point diagnostic, but useful longitudinally.

How often should an athlete test?

Every 3 to 4 months is common for serious athletes, often timed to training blocks (start of a block as baseline, peak/competition phase, recovery phase).

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About this guide. Educational content for general awareness. Chxhealth is a biomarker and genetic data provider. We do not diagnose, treat or prescribe. Our service supports your wellbeing journey alongside your healthcare professional. For medical advice about your health or results, please speak to a qualified clinician.