Chasing Down Your Next PR? Set These Biomarkers In Your Sights


Spring is here, and that means race season is in full swing; after months of enduring winter training, it's finally time to put your hard work to the test! Whether you're looking for a better result the next time you toe the line, an edge over the competition, or even a shiny new PR, your biomarkers can make all the difference. Here's how some of the key markers we test can help you have your healthiest and strongest race season yet.


Energy and metabolism markers

Vitamin B12

This B vitamin is critical for many body functions including the production of red blood cells, DNA and RNA synthesis, and proper brain and nervous system health. And if you thought low iron levels were the only cause of anemia, you'd be surprised – insufficient B12 can result in improper red blood cell production and, as a result, classic anemia symptoms.

Low levels can also cause skin numbness, poor coordination, and decreased cognitive function – which won't only influence your competitive performance, but also your general wellbeing. It stands to reason, then, that optimizing this biomarker can ensure your body and brain are functioning at their best.

The average omnivore can get B12 from beef, clams, fish, eggs, and dairy products. Since this nutrient is found in very few plant-based foods, vegetarians and vegans can opt for the wide variety of fortified foods such as certain non-dairy milks, cereals, and nutritional yeast.


Commonly known as "blood sugar," glucose is the body’s primary source of energy. That means that, as an athlete, it's also the number one fuel for your workouts. So if you want o crush your training – both in output and in endurance – adequate glucose levels are key.

While levels naturally fluctuate throughout your day, perpetually-elevated glucose levels can lead to weight gain, elevated triglyceride levels, high cholesterol, and high blood pressure. Increasing your intake of fiber-rich foods is one of the most effective recommendations to optimize your blood sugar levels. Depending on your current diet, exercise routine, and other goals based on your biomarkers, some of our supplement recommendations may also be effective for you. 


Bone and muscle health

Vitamin D

This nutrient plays an important role in both bone and muscle health, as it helps to add calcium to bones and regulate the development and maintenance of the nervous system and skeletal muscle. These processes are of the utmost importance for athletes – they help prevent the occurrence of stress fractures, reduce inflammation, and promoting muscle health.

Research has shown that vitamin D supplementation in those who were deficient reduced the occurrence of injury and increased explosive power.1 There's also a strong positive relationship between vitamin D levels and aerobic fitness, and a negative one with BMI.2 So what does this all mean? By optimizing your vitamin D levels, you can improve your output – both in power and endurance – as well as body composition, which can have improved performance implications in itself. 

According to a country-wide analysis, 42% of US adults are Vitamin D deficient.3 But before you let this number spur you into supplementing, you should know that getting your blood tested is strongly recommended before starting any new supplementation regimen, especially with vitamin D; too much of this nutrient can be dangerous and lead to a build-up of calcium in your blood (hypercalcemia), nausea, vomiting, and weakness.4


Stress, overtraining, and inflammation


This steroid hormone is released by the body in response to stress and plays a role in energy regulation, metabolism, and immune system function. While cortisol levels naturally fluctuate throughout the day (they're highest in the morning), perpetually-high levels can result in poor sleep quality, increased anxiety, depressed moods, digestive problems, decreased bone density, loss of muscle tissue, blood sugar imbalances, reduced immune function, and weight gain. See how cortisol levels are key for training and recovery?

Training adds significant stress to our bodies, so it's important to find ways to mitigate that stress which work for your lifestyle. Some strategies include following a healthy diet with consistent meal timing, getting adequate sleep, relaxation techniques such as meditation or yoga, avoiding rapid increases in training loads, and scheduling adequate rest days in your training cycles.5,6 Need help with choosing the right foods for you? Our food recommendations and food basket are great guides for centering your diet around your biomarkers.

Testosterone-to-cortisol ratio

Now that we know the importance of healthy cortisol levels, let's move on to testosterone levels. The ratio of these two biomarkers is a strong indicator for overtraining. Testosterone signals our muscles to grow, and cortisol is a signal for muscle breakdown, so by directly comparing the two, we can see if our body is in a state of increasing or decreasing muscle mass. A lower ratio may be an indicator of overtraining, high-stress levels, or poor quality sleep, any of which can result in muscle breakdown and fatigue. A higher ratio can show that you’re getting adequate rest and recovery.

High-sensitivity C-reactive protein (hsCRP)

This is a general inflammation biomarker which tells us about the overall inflammation levels in the body.7 Excessive physical activity can lead to increased levels, which makes this biomarker especially relevant for athletes like ultra-runners, marathoners, and triathlon racers.8 Elevated hsCRP levels are also associated with decreased bone strength, decreased immune health, and poorer heart health. Inflammation in athletes can be combated with appropriate training and recovery strategies – avoiding significant increases in training, specifically run training, will help to keep hsCRP levels low. 


Iron Group

Iron is critical for a number of physiological functions, including oxygen transport, which is especially important for active individuals; higher physical output causes a higher oxygen demand. Inflammation caused by our training output can also reduce iron absorption, doubling down on the importance of iron during training. Once you know what your iron marker levels are, our InsideTracker recommendations can help guide you on how to optimize your iron intake and your performance.


The Takeaway

As athletes, we spend both our time and money on training, coaching, travel, race registration, supplementation and food to feed our efforts. With all the hard work invested in racing, testing with InsideTracker can give you the knowledge and tools to ensure you’re healthy and strong. Why not toe the line knowing you’ve done everything possible to stay healthy, strong, and perform at your best this season?

Add your blood to your training team with InsideTracker!

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  1. Wyon, Matthew A., et al. "The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: A controlled study." Journal of Science and Medicine in Sport 17.1 (2014): 8-12.
  2. Forney, Laura A., et al. "Vitamin D Status, Body Composition, and Fitness Measures in College-Aged Students." The Journal of Strength & Conditioning Research 28.3 (2014): 814-824.
  3. Forrest, K., & Stuhldreher, W. (2011). Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research, 31(1), 48-54. doi: 10.1016/j.nutres.2010.12.001
  4. Mayo Clinic. “Vitamin D toxicity: What if you get too much?” Retrieved from:
  5. Jones, T., Howatson, G., Russell, M., & French, D. (2016). Performance and Endocrine Responses to Differing Ratios of Concurrent Strength and Endurance Training. Journal Of Strength And Conditioning Research, 30(3), 693-702. doi: 10.1519/jsc.0000000000001135
  6. Carrière, K., Khoury, B., Günak, M., & Knäuper, B. (2017). Mindfulness-based interventions for weight loss: a systematic review and meta-analysis. Obesity Reviews, 19(2), 164-177. doi: 10.1111/obr.12623
  7. Kamath, Deepak Y. et al. “High Sensitivity C-Reactive Protein (hsCRP) & Cardiovascular Disease: An Indian Perspective.” The Indian Journal of Medical Research 142.3 (2015): 261–268. PMC. Web. 26 Apr. 2018.
  8. Ertek, Sibel, and Arrigo Cicero. “Impact of Physical Activity on Inflammation: Effects on Cardiovascular Disease Risk and Other Inflammatory Conditions.” Archives of Medical Science : AMS 8.5 (2012): 794–804. PMC. Web. 26 Apr. 2018.


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