The Cyclist’s Guide to Blood Biomarkers

More and more serious amateur cyclists are starting to get regular blood tests as a basis for training and health monitoring. Blood biomarkers provide information that power meters and heart rate monitors cannot tell you—what is actually happening inside your body.

Why Do Cyclists Need Regular Blood Tests?

Cycling training has unique effects on the body:

• High training volume can lead to specific micronutrient deficiencies
• Hormonal balance can be affected by training intensity
• Bone and immune system health require special attention
• Early detection of problems (such as anemia) can prevent a significant drop in training effectiveness

Recommended Frequency: Serious cyclists should get tested 2 times per year (before and after the season)

Key Blood Marker Analysis

1. Hemoglobin and Red Blood Cells

Cycling is an aerobic sport, and oxygen-carrying capacity is crucial:

Marker	Normal Range (Adults)	Impact on Cycling
Hemoglobin (Male)	13.5-17.5 g/dL	Low → Decreased aerobic capacity
Hemoglobin (Female)	12.0-15.5 g/dL	Low → Increased fatigue
Hematocrit	Male 41-53%, Female 36-46%	Low → Insufficient oxygen-carrying capacity

Sports Anemia: May occur in high-training-volume cyclists, with causes including:

• “Foot-strike hemolysis” from pedaling impact
• Iron loss through sweat
• Gastrointestinal micro-bleeding (during high-intensity rides)

2. Iron Metabolism Markers

Marker	Normal Range	Common Issues for Cyclists
Serum Iron	60-170 μg/dL	Decreases after low training volume
Ferritin	Male 15-200, Female 12-150 ng/mL	Recommended > 50 ng/mL for cyclists
Transferrin Saturation	20-50%	< 20% indicates iron deficiency

The Special Importance of Ferritin:

• Even with normal hemoglobin, low ferritin (<50) can affect performance and recovery
• Studies show ferritin > 75 ng/mL is optimal for athletes
• Low ferritin: fatigue, slow recovery after training, “legs that won’t hold up”

3. Vitamin D

Marker	Ideal Range	Common Status Among Taiwanese Cyclists
25-OH Vitamin D	40-80 ng/mL	Generally insufficient among Taiwanese urban residents (commonly <30)

The importance of vitamin D for cyclists:

• Bone health (especially important, see the bone density article)
• Muscle function and strength
• Immune system regulation
• Hormone synthesis

Supplementation Advice: If below 40 ng/mL, consider supplementing 2,000-4,000 IU of vitamin D3 daily

4. Hormonal Markers

Marker	Normal Range	Significance
Testosterone (Male)	300-1,000 ng/dL	Low → Possible overtraining
Cortisol	6-23 μg/dL (morning)	High → Chronic stress/overtraining
Testosterone/Cortisol Ratio	Individualized baseline	Low ratio → Indicator of overtraining
Thyroid Function (TSH)	0.4-4.0 mIU/L	Affects metabolism and fatigue

5. Inflammatory Markers

Marker	Normal Value	Significance
CRP (C-Reactive Protein)	< 1.0 mg/L (optimal for cardiovascular health)	High → Chronic inflammation or overtraining
White Blood Cell Count	4,000-11,000/μL	Very low → Immunosuppression (after high training volume)

6. Muscle Damage Markers

Marker	Normal Value	When to Use
CK (Creatine Kinase)	Male <200, Female <170 U/L	Can normally rise to 500-2,000 after heavy rides
Myoglobin	< 70 μg/L	Extremely high levels warrant caution for rhabdomyolysis

How to Get Blood Tests in Taiwan?

Items Covered by National Health Insurance

Blood tests included in general health checkups (partially covered by NHI):

• Complete Blood Count (CBC)
• Liver and kidney function
• Lipid panel (4 items)

Additional Self-Paid Tests

Additional tests available at your own expense (cost approximately NT$2,000-5,000):

• Ferritin, complete iron metabolism panel
• Vitamin D (25-OH)
• Hormone panel (testosterone, cortisol)
• Thyroid function

Channels in Taiwan offering athlete blood analysis services:

• Sports medicine clinics (available at major hospitals such as NTU Hospital, Veterans General Hospital, Chang Gung Memorial Hospital, etc.)
• Certain private medical laboratory services (no physician prescription required, self-paid)

Actions to Take After Detecting Abnormalities

Problem	Possible Causes	Recommended Actions
Low hemoglobin	Iron deficiency, excessive training volume	Increase iron intake, consult a physician
Low ferritin	Inadequate diet, intestinal absorption issues	Increase red meat and spinach intake, consider supplements
Low vitamin D	Insufficient sun exposure	Supplement D3, get moderate sun exposure
Low testosterone	Overtraining, insufficient sleep	Reduce training load, improve sleep

Conclusion

Blood biomarkers are an underutilized tool in cycling training. A blood test every six months costs a few thousand dollars but can uncover hidden problems and multiply your training efficiency. Treat it as a training tool just as important as your power meter and heart rate monitor.

Related Reading

• Biomarkers of Athletic Performance: Reading Your Training Status Through Blood Tests, Understanding Your Body’s Training Feedback
• Heart Safety in Cycling: When Do You Need an Exercise ECG?
• Special Health Considerations for Female Cyclists: Hormones, Bones, and Equipment
• Protein Requirements for Cyclists: The Science of Muscle Maintenance and Repair