1. Total and Free Testosterone
The headline hormone. Total testosterone tells you overall production. Free testosterone — the portion not bound to SHBG — tells you how much is actually available to your tissues. Test both. Many athletes have acceptable total testosterone but low free testosterone because elevated SHBG is binding it. Test quarterly, or before and after any significant change to training or body composition.
2. SHBG (Sex Hormone Binding Globulin)
SHBG binds to testosterone and makes it unavailable. High SHBG drives down free testosterone even when total is fine. Dietary factors — particularly low fat intake and high fibre — as well as thyroid function all influence SHBG. Test alongside testosterone.
3. Haematocrit and Haemoglobin
These tell you about your blood's oxygen-carrying capacity. For endurance athletes especially, both are critical. Haematocrit above 50% in males can indicate dehydration or a response to training altitude — but in some contexts warrants investigation. Test twice a year, or if performance drops unexpectedly.
4. Ferritin
Iron stores, not serum iron. Serum iron fluctuates day to day. Ferritin is the long-term picture. Low ferritin is one of the most common and underdiagnosed causes of fatigue and reduced VO2 max in athletes, particularly females. Optimal ferritin for athletes sits between 50 and 150 µg/L — the standard lower limit of 15 is far too low. Test every 6 months.
5. Vitamin D (25-OH)
The standard lower limit for vitamin D is around 50 nmol/L. Optimal for athletic performance and immune function is closer to 100–150 nmol/L. Deficiency is extremely common — especially in winter months and in people who train indoors. Test every 6 months, adjust supplementation based on results.
6. CRP or hs-CRP
C-reactive protein is a marker of systemic inflammation. Chronically elevated CRP blunts adaptation to training and increases injury risk. Optimal is below 1 mg/L. Useful for monitoring overtraining and recovery status. Test quarterly.
7. ALT and AST
Liver enzymes — but in athletes, often a proxy for muscle damage rather than liver stress. Useful for monitoring training load and recovery. An athlete with normal kidney and liver function but elevated ALT post-heavy training week is usually fine. An athlete with elevated ALT after a rest week warrants further investigation. Test quarterly.
8. Fasting Glucose and Insulin
Together these give you insulin sensitivity data — arguably one of the most important metabolic markers for body composition and long-term health. Fasting glucose above 5.5 mmol/L or fasting insulin above 60 pmol/L signals early insulin resistance. Test every 6 months.
9. Lipid Panel: LDL, HDL, Triglycerides, and ApoB
Don't just look at total cholesterol. LDL particle count matters more than LDL concentration — and ApoB is the best proxy for that. Athletes often have slightly elevated LDL from high saturated fat intake. Context matters. Test every 6 months.
10. TSH, Free T3, Free T4
Thyroid function is often overlooked in athletes. Subclinical hypothyroidism — TSH slightly above range with normal T3/T4 — is common and associated with fatigue, slow recovery, and difficulty losing body fat. Don't just test TSH. Get the full panel. Test annually, or if unexplained fatigue appears.