What is the impact of 100-mile training on health?

By Henry Howard

This represents the second half of an experiment this year on how 100-mile training influences my health and fitness. In January, before I began training for the Burning River 100-miler, I had a blood draw from InsideTracker.

Those findings, which I wrote about here, serve as the baseline. I am revisiting those results now to compare them with my recent test, which was taken July 21 during my taper period for Burning River. The biggest highlight is that I have the lowest number of “at risk” markers that I have seen in years of testing with InsideTracker.

I have received regular InsideTracker tests so that I can keep an eye on how my training, recovery and nutrition are having an overall impact on my health. I trust them for their thorough analysis, easy-to-compare data and personalized recommendations, based on my age, fitness level, dietary preferences and more. I’ve learned a lot about my health over the years and regularly use the InsideTracker information and recommendations to improve my health.

Impact of 100-mile training on health

Overall, recent data show an improvement in health, according to the biomarkers. A comparison over my previous tests over the past two years (note that I trained for and completed 100-milers the past two Julys):

• Optimized: 37 (July 2025), 39 (January 2025), 35 (September 2024 ), 36 (July 2024), 34 (December 2023), 34 (July 2023)

• Needs improvement: 11 (July 2025), 6 (January 2025) 9 (September 2024 ), 9 (July 2024), 8 (December 2023) 9 (July 2023)

• At risk: 4 (July 2025), 7 (January 2025), 8 (September 2024 ), 7 (July 2024), 10 (December 2023), 7 (July 2023)

Among the biomarkers that improved were:

Iron: Decreased from 188 to 130, still in the needs improvement zone. My iron score has been all over the board. Previous to the 130 and 188 scores, it was 107, 139, 216, 169 and 124. Ideally, it should be between 75 and 115, while the needs improvement zone is from 115 to 180. The body stores excess iron in the liver, heart, and pancreas, and high levels of iron can damage these organs. High levels of iron can also cause your blood sugar to rise. Since I am plant-based, I’ll need to focus on plant-based foods and weekly supplements to maintain some balance of normalcy.

Sodium: Increased from 130 to 135, putting it just inside the needs improvement zone. Notably, this is the first time in years that I have rated that well in this category. While this is a solid gain, I need to keep focusing on getting in enough sodium. (Also worth pointing out is that a low score might be related to overhydration before the blood draw.)

Basophil percentage: Went from “at risk” to optimized. Basophils are a type of white blood cell type that act as infection fighters in the immune system. Basophils are typically activated during an allergic response, but otherwise exist at very low levels in the body. An optimal basophil level, when combined with measurements of other white blood cells and inflammation markers, generally indicates reduced inflammation and better overall health.

Transferrin saturation (TS): Also went from “at risk” to optimized. Optimized TS is important for maintaining iron balance in the body and is associated with having more energy, being stronger, clearer thinking and a more resilient immune system.

What’s next

Still there is work to be done. Among the areas I’ll monitor and focus on:

• Iron: This biometric has been a roller coaster, as noted. I generally try to take a supplement weekly so the levels do not get too high. I’ll also focus on plant-based foods high in iron which include lentils, spinach, cashew nuts, pumpkin seeds, quinoa, tofu, chickpeas and dried apricots. 

• Sodium levels. I’ve been using electrolytes more frequently, especially around the time of the test. So I’ll need to keep that up to maintain a good balance.

• Cortisol: In my recent test, my score returned to its normal “at risk” level. The previous test from six months ago showed an improvement. InsideTracker recommends increasing my intake of ashwagandha to 600 mg daily. From InsideTracker: “A large body of research has found that ashwagandha effectively lowers cortisol levels by up to 27%! While the exact mechanism for ashwagandha's effects is unclear (like many adaptogens), some research suggests that ashwagandha directly inhibits the release of cortisol from the adrenal glands. Ashwagandha may also reduce the perception of stress, meaning that very stressful things don't seem as bad when taking ashwagandha.”

Conclusion

There was definitely improvement during my six months of training for a 100-miler, as shown by the data. That’s reassuring, especially for a masters athlete.

I am thankful for good genes, the choices I’ve made to adapt a plant-based diet and the ability to run. And all of those elements allow me to live healthfully, at least according to InsideTracker. And, of course, I’m grateful for InsideTracker’s thorough analysis, personal recommendations and easy-to-use data.