Improve your fitness

Whether you want to improve your endurance or muscle strength, stay on top of your health with subscription home blood tests and GP advice.

What can a blood test tell you about fitness?

A blood test can give you insights into a range of factors that can affect your fitness. For example, nutrients and certain hormones play a big role in how you perform and recover from exercise. They can also affect your sleep — which is one of the most important things for muscle repair.

Combined with GP-reviewed results and evidence-based ways to improve your health, understand how to perform at your best.

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Blood tests related to fitness


Vitamin D

Vitamin D helps your body absorb calcium and helps with maintaining healthy skin and bones. It also plays an important role in your immune system. Vitamin D deficiency is linked to fatigue, bone and muscle pain, as well as getting ill more often than usual.



Your body uses iron to make haemoglobin — a part of red blood cells that carry oxygen around your body. If you don't get enough iron you might develop iron deficiency anaemia, which can affect your fitness performance. Tiredness, shortness of breath, and heart palpitations are signs you might be deficient.


Folate (vitamin B9)

Folate plays an essential role in producing red blood cells — these carry oxygen around your body. If your folate levels are low, you might feel tired and less motivated. You might also experience pins and needles, heart palpitations, shortness of breath, and muscle weakness.


Vitamin B12

Vitamin B12 is essential for a healthy brain and nervous system. It also works closely with folate to make red blood cells — these carry oxygen around your body. If you don't get enough vitamin B12, it can impact your endurance and performance.



Testosterone is a hormone that's essential for women and women. It's important for muscle mass and strength, bone health, and red blood cell production (these transport oxygen around your body).


Liver function

Your liver plays a key role in digesting and metabolising food. This process helps provide energy for your body to use. If your liver isn't functioning correctly it can affect this process and your fitness levels. Poor liver health can also cause low energy levels.

Your journey to better fitness

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Laura's plan

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Laura wants to make sure she’s getting enough of the nutrients that help her recover from marathon training.

Vitamin B12 to support energy
Vitamin B12
for muscle recovery
Iron to support endurance

Your sample will be analysed by a CQC-registered and UKAS accredited lab. This finger-prick test and kit are CE-marked.

Want to improve your fitness?

Whether you're training for your next marathon or want to improve your lifestyle habits, take the first step with a home blood test.

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Our blood testing kits are CE-marked, and we work with UKAS accredited labs who are registered with the CQC.

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