Original episode & show notes | Raw transcript
This document provides a comprehensive educational review of the key topics discussed in the Empirical Cycling Podcast episode featuring Dr. Fabiano, a medical doctor and PhD with expertise in human physiology, genomics, and proteomics. The discussion centers on the intersection of athletic training, illness, and recovery, providing evidence-based insights and practical recommendations for athletes and coaches.
One of the most common dilemmas for an athlete is whether to train through a minor illness. The podcast introduces a widely used clinical rule of thumb called the “Neck Check.”
Concept: The rule provides a simple guideline for deciding whether to exercise or rest.
Symptoms Above the Neck: If symptoms are confined to the head (e.g., runny nose, sore throat, sneezing), light to moderate exercise is generally considered acceptable.
Symptoms Below the Neck: If symptoms are systemic and affect the entire body (e.g., fever, myalgia (muscle aches), chest pain/congestion, resting tachycardia), complete rest is strongly advised.
Physiological Rationale: Engaging in exercise with systemic symptoms diverts precious metabolic energy away from the immune response. The body needs all available resources (glucose, amino acids) to fight the infection effectively. Exercising splits these resources between muscle activity and immune function, which can:
Prolong the Illness: The immune system is less effective, extending the recovery period.
Worsen the Illness: A minor infection can escalate into a more severe condition, like the “walking pneumonia” example mentioned, potentially risking the entire season.
Delay Return to Training: A few days of complete rest often leads to a faster overall recovery and a quicker return to productive training than trying to “push through” it.
Dr. Fabiano explains that even a mild systemic illness significantly impairs the body’s ability to perform and adapt to training. The key physiological changes include:
Increased Risk of Dehydration: A fever increases sweat rate. The podcast also mentions a potential decrease in the production of Antidiuretic Hormone (ADH), a hormone that instructs the kidneys to conserve water. A reduction in ADH would lead to increased urine production, further compounding dehydration.
Increased Protein Catabolism: The immune system requires a substantial amount of amino acids to produce new immune cells (like lymphocytes and neutrophils) and antibodies. The body breaks down muscle tissue (protein catabolism) to supply these building blocks, which is counterproductive for an athlete.
Reduced Glucose Availability: Immune cells are highly glycolytic, meaning they rely heavily on glucose for energy. This creates competition for glucose that would otherwise be used to fuel exercising muscles.
Cardiovascular Strain: Illness can cause an increase in peripheral vascular resistance, meaning blood vessels may constrict. This makes it harder for the heart to pump blood to the working muscles, reducing oxygen delivery and overall efficiency.
Reduced Endurance Capacity: As a result of these factors, studies have shown up to a 25% reduction in endurance capacity. This can manifest as a higher Rate of Perceived Exertion (RPE) for a given power output or an inability to complete workouts that are normally manageable.
The podcast discusses the complex relationship between how much an athlete trains and their vulnerability to illness, referencing two key models.
The J-Curve Hypothesis: This is the traditional model, primarily applied to amateur athletes.
Sedentary Individuals: Have a moderate risk of infection.
Moderately Active Individuals: Have the lowest risk of infection. Regular, moderate exercise appears to bolster the immune system.
Overtrained/Elite Athletes: As training volume and intensity reach very high levels, the risk of infection rises again, surpassing that of sedentary individuals. This is due to the immense physiological stress, which can temporarily suppress immune function.
The S-Curve Hypothesis: A more recent model proposed for elite-level athletes.
This model suggests that highly trained elite athletes may develop adaptations that make their immune systems more resilient to high training loads compared to amateurs. They may not see the same dramatic spike in infection risk at peak training loads.
Potential Reasons: Dr. Fabiano suggests this could be due to better overall management of energy availability, nutrition, and recovery, as well as superior physiological adaptations developed over years of training.
The Role of Life Stress: For amateur athletes, life stress (work, family, lack of sleep) is a significant confounding variable. This external stress adds to the training stress, further taxing the body’s resources and increasing the likelihood of immune suppression and illness.
Dr. Fabiano emphasizes that while no “magic bullet” supplement exists, sound nutritional and lifestyle habits are critical.
Illness Prevention:
Basic Hygiene: Frequent hand washing, using masks indoors during periods of high transmission, and avoiding touching the face are foundational.
Avoid Sharing: Don’t share water bottles, towels, or equipment.
Stress Management: Learning to cope with life stress is crucial, as the physiological stress response (“fight or flight”) can suppress immune activity.
Moderate Alcohol: Alcohol consumption, especially binge drinking, has been shown to impair immune function for several hours. This is particularly risky after a hard competition or workout when the body is already stressed.
Probiotics: There is promising evidence that probiotics (found in yogurt, kombucha) can support gut health, which is intricately linked to the immune system.
Nutrition During Illness:
Prioritize Carbohydrates: Contrary to low-carb diet trends, carbohydrates are essential during illness. They provide readily available glucose for immune cells and, when consumed in solutions (like sports drinks), aid in hydration.
Maintain Balanced Intake: Do not attempt a weight-loss diet while sick. The body is in a state of high metabolic demand and needs adequate protein, healthy fats (for hormone production), and micronutrients to recover.
Hydration is Key: Maintain high fluid intake to counteract losses from fever and support overall cellular function.
Supplements (Vitamin C, etc.): The scientific literature shows conflicting or weak evidence for high-dose supplements like Vitamin C in treating an active cold. A well-balanced diet is a more reliable strategy.
A structured and patient approach is essential to avoid relapse.
Symptom-Free First: Ensure all “below-the-neck” symptoms (fever, aches, chest congestion) have been completely resolved for at least 24 hours.
Start Easy and Short: The first session back should be very light and brief (e.g., 30-minute easy spin). The goal is to reintroduce activity, not to chase fitness.
Gradual Progression: If the first session is well-tolerated, gradually increase the duration and then the intensity over several days. Monitor your body’s feedback closely.
Listen to Your Body: If symptoms return or you feel unusually fatigued, stop immediately and take another day or two of complete rest. As the podcast notes, it often takes more mental toughness to rest than to push through.
Towards the end, Dr. Fabiano discusses his PhD research, offering a glimpse into the complexity of human physiology.
The Renin-Angiotensin System (RAS): This is a critical hormonal system that regulates blood pressure and fluid balance. It plays a key role in cardiovascular function by influencing blood vessel constriction, blood volume (via kidney function), and heart function.
Sex-Specific Regulation: Dr. Fabiano’s research explored how this system is regulated differently in men and women at the genetic level.
He studied proteins that act as transcription factors in the promoter region of genes. (A promoter region is a segment of DNA where regulatory proteins bind to control how often a gene is “read” and turned into a protein).
He specifically looked at the SRY protein, which is coded on the Y chromosome and is therefore unique to men, and compared its function to similar proteins (the SOX family) present in both sexes.
Implications: These findings suggest that fundamental differences in genetic regulation of the RAS may help explain why men and women have different incidences and progressions of cardiovascular diseases like hypertension (high blood pressure). This highlights how deeply rooted physiological differences are and why a one-size-fits-all approach to medicine and physiology is often inadequate.