It’s All in the Blood: Lab Tests Every Endurance Athlete Should Know About
As an endurance athlete, you already know performance is about more than just training volume and watts. To truly perform at your best, you need to understand what’s going on under the hood—starting with your bloodwork.
Here’s a breakdown of essential lab tests every endurance athlete should consider, what to ask your provider for, and when to get them done for maximum insight.
Why Lab Tests Matter
Lab tests can give you early insight into potential issues like fatigue, poor recovery, or performance plateaus—before they show up in your training data. They help identify deficiencies, imbalances, or overtraining symptoms that can’t be seen from the outside.
Essential Lab Tests for Endurance Athletes
1. Complete Blood Count (CBC)
Why it matters: Screens for anemia and provides a snapshot of your overall health.
Ask for: Red blood cell count, hemoglobin, and hematocrit. These markers are crucial for oxygen transport—and your endurance.
2. Ferritin
Why it matters: Measures stored iron levels, essential for energy production.
Ask for: A ferritin test specifically. Endurance athletes often experience low ferritin due to higher blood volume and sweat loss.
3. Vitamin D
Why it matters: Supports immune function, bone health, and muscle recovery.
Ask for: A 25(OH)D blood test. Especially important if you train indoors or live in areas with limited sun exposure.
4. Vitamin B12 and Folate
Why it matters: Key for red blood cell formation and energy metabolism.
Ask for: Both B12 and folate levels, especially if you’re plant-based or experience unexplained fatigue.
5. Magnesium (RBC Test)
Why it matters: Regulates muscle contractions, energy production, and recovery.
Ask for: Magnesium RBC (not just serum magnesium) for more accurate results.
6. Thyroid Function Panel
Why it matters: Affects metabolism, energy levels, and recovery.
Ask for: TSH, Free T3, and Free T4. Imbalances could indicate hypothyroidism or hyperthyroidism.
7. Hormone Panel
Why it matters: Monitors signs of overtraining or under-recovery.
Ask for: Cortisol and testosterone. Elevated cortisol or low testosterone can be a red flag for excessive training stress.
8. Lipid Profile
Why it matters: Even fit athletes need to watch their heart health.
Ask for: HDL, LDL, and triglycerides. A healthy cardiovascular system supports long-term endurance capacity.
9. Omega-3 Index
Why it matters: Tracks levels of essential fatty acids (EPA & DHA) that reduce inflammation and support recovery.
Ask for: The Omega-3 Index blood test. Aim for 8% or higher.
10. comprehensive metabolic panel (CMP)
Why it matters: Gives insight into liver and kidney function, electrolytes, and glucose balance.
Ask for: A full CMP to ensure your internal systems are handling your training load.
When to get lab tests done
Off-Season or Recovery Phase: Best time to establish a baseline when the body isn’t under peak training stress.
Pre-Season: Helps you identify and correct issues before your volume increases.
Post-Race: Useful for checking stress markers and nutrient depletion after a big event.
The Takeaway
Staying on top of your blood markers is just as important as monitoring your watts, heart rate, or training load. These tests help you train smarter, recover better, and avoid preventable setbacks.
At Mach1 Performance, we’re here to help you take a holistic approach to athletic excellence—from workouts to wellness. Want guidance on interpreting your labs and making actionable changes?