“Those who think they have no time for exercise will sooner or later have to find time for illness.” — Edward Stanley, Earl of Derby
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Many people think of fitness as a way to feel good and help them accomplish their goals in life. However, a third value is often not covered by mainstream media. Being fit protects you from the onset of disease and resulting rapid decline. Physical fitness, especially cardiorespiratory fitness, is strongly linked to protection against a wide range of diseases and lower mortality. Higher fitness levels consistently reduce the risk of cardiovascular disease, age-related diseases, and premature death, even in those with high genetic or traditional risk factors.
Practicing The 6 Pillars of health, which I have talked about before(here) creates a protective effect that shields against the ravages of disease. If you have the flu, the fitter you are, the less likely chance you end up in the hospital. If you get cut you have a less likely chance of getting an infection. If you eat too much sugar or carbohydrates, the less likely chance you have of developing insulin resistance.
Health is a Continuum
Health can be thought of as a continuum where you may start at "sickness" progress to "wellness" and hopefully end up at "fitness". Along the way we can use specific markers and measurements to see where you may lie along the path.
For example the biggest chronic disease today, insulin resistance, can be measured with a glucometer, A1c, insuline levels, and an oral glucose challenege test. For simplicity well just use the hemoglobin A1c which measures a persons average blood sugar across the last 2-3 months. You can see the values across the continuum below.
If your A1c is above 7.0 then you may start to develop organ damage. For example you may start to have blurry vision because high sugar levels are damaging the blood vessels of your eye. In the case of men they can develop erectile dysfunction, a potent motivator, and seek out care immediately.
From Medications to Lifestyle Habits
These types of possible end-organ damage that occur at the left of the continuum need to be delt with quickly. The problem is they may not be felt by our body immediately and therefore not registered by our brains as a high-level threat. Without a trigger this can lead to complacency and a lack of willingness to change our lifestyle habits. Using medications to move a person out of this pathological zone and at the same start motivational lifestyle habit training is a much better option than medications alone.
Medications can quickly move you out of the harmful effects of disease and stave off life-threatening complications like diabetic ketoacidosis which will get you admitted to the hospital.
The goal, if possible, is to eventually get people off of medications. This is easier said than done because our brains put up a lot of resistance against suggestions to change. Having a group or friend (social connection, pillar 5) to help you along the way provides a strong lever for action.
Moving from Wellness to Fitness
As the medications start to drop off you can begin to build your shield of fitness by continuuing healthy habits such as resistance training (lifting weights) and cardiovascular exercise. Biochemically this is accomplished though the following mechanisms.
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Reduced chronic inflammation. Strength training lowers pro-inflammatory cytokines (like TNF-α, IL-6 in their chronic form) and increases anti-inflammatory ones. Lower inflammation means fewer chronic disease triggers and better immune regulation.
- Increased circulation of immune cells. Resistance exercise temporarily boosts the number and activity of lymphocytes and natural killer cells, improving the body’s ability to detect and neutralize pathogens. This is seen in cancer patients undergoing chemotherapy.
- Improved insulin sensitivity. Muscle tissue acts as the primary site for glucose disposal. Stronger, more metabolically active muscles reduce hyperglycemia, lowering the risk for infections that thrive in high-sugar environments.
- Lower visceral fat. Less visceral fat means reduced inflammatory signaling and better hormone regulation.
- Higher anabolic hormones. Regular lifting helps maintain testosterone, growth hormone, and IGF-1 — all of which support immune cell function and tissue repair.
- Better cortisol regulation. Chronic stress and high cortisol can suppress immunity; resistance training helps normalize stress responses.
- Injury and frailty prevention. Stronger muscles and bones reduce fall risk and related complications — which are especially dangerous in older adults.
- Better lung and heart reserve. Compound lifts and higher-rep resistance work support cardiovascular and respiratory function indirectly, making the body more resilient during illness.
As you can see resistance training prepares your whole physiology — from immune cells to hormones to musculoskeletal reserve — to handle illness better and recover faster. This is why, in age management medicine, progressive resistance training is considered as fundamental as nutrition and sleep in a long-term health plan.
I'll leave you with this Question.
How would you like to build a shield against chronic illness?
Checkout the latest Clear Health Podcast episode with Dr. Lorena Pacheco PhD from Harvard as she discusses the power of an Avocado!
References
- Yale School of Medicine. Strength training and the immune system: A Q&A with Ryan Steele, DO, MS. Yale School of Medicine. Published 2023. Accessed August 10, 2025. https://medicine.yale.edu/news-article/strength-training-and-the-immune-system-a-qanda-with-ryan-steele/
- Nieman DC, Wentz LM. The compelling link between physical activity and the body’s defense system. J Sport Health Sci. 2019;8(3):201-217. doi:10.1016/j.jshs.2018.09.009
- Bartlett DB, Willis LH, Slentz CA, et al. Resistance exercise and immune function in humans. Semin Cell Dev Biol.2022;123:122-131. doi:10.1016/j.semcdb.2021.06.014
- Ahtiainen JP, Hulmi JJ, Kraemer WJ, et al. Chronic resistance training modulates inflammatory monocytes and circulating myokines in older adults. Mol Cell Endocrinol. 2024;580:111980. doi:10.1016/j.mce.2024.111980
- Pedersen BK, Febbraio MA. Muscles, exercise and obesity: skeletal muscle as a secretory organ. Nat Rev Endocrinol. 2012;8(8):457-465. doi:10.1038/nrendo.2012.49
