What is Thyroid Stimulating Hormone & Why Is it Important for Athletes?

What Is TSH?

TSH controls thyroid hormone production, regulating metabolism, energy, and temperature balance. Abnormal TSH levels can signal underactive or overactive thyroid function, both of which can impact endurance, recovery, and weight management.

"TSH controls your thyroid gland’s output, influencing energy, metabolism and temperature regulation. Abnormal levels can indicate under- or overactive thyroid function, both of which can impact performance and recovery. I usually suggest getting a baseline thyroid function test, including antibodies once, then testing the function of the thyroid every 6 months, which means TSH, alongside free T4 and free T3 for a full assessment of thyroid health."

Dr Thom Phillips

What are normal Thyroid Stimulating Hormone (TSH) levels for athletes?

We looked at blood test data from EDGE customers and found the median thyroid stimulating hormone levels for women are 2.23 mIU/L and 2.11 mIU/L for men.

Here is a breakdown of TSH levels by age:

Source: EDGE customer blood test results Apr 2023 – March 2025.

The labs we used to analyse blood samples state a healthy range for TSH is generally between 0.27 – 4.2 mIU/L.

Performance Relevance

Thyroid hormones play a vital role in regulating energy levels, metabolism, and performance. Disruptions in thyroid function can lead to:

• Low thyroid (high TSH) → fatigue, weight gain, low mood

• High thyroid (low TSH) → anxiety, muscle loss, high heart rate

Why Athletes Should Test TSH

Testing TSH can help uncover hidden hormonal imbalances that may be affecting your training, recovery, and overall health. It’s particularly useful:

• When experiencing unexplained fatigue, weight change, or cold intolerance

• To assess thyroid function when struggling to recover or perform

• Alongside T3 and T4 for complete thyroid insight

In Summary

• TSH controls your body’s energy regulator, the thyroid

• Important for fatigue, recovery, and metabolic rate

• Best tested with T3 and T4 to confirm thyroid status