Original episode & show notes | Raw transcript
This document breaks down the core concepts discussed in the podcast episode featuring Empirical Cycling coaches Kolie Moore and Fabiano. The conversation revolves around three interconnected pillars of effective endurance training: understanding and using the Rate of Perceived Exertion (RPE), the critical role of detailed feedback, and the science behind how our bodies adapt to training stress.
RPE is a tool to quantify the subjective experience of effort. While we have objective data like power meters and heart rate monitors, RPE integrates a vast amount of physiological and psychological information into a single feeling. The podcast highlights two key scales developed by Gunnar Borg.
History and Design: This was the first scale, designed to have a direct, linear correlation with heart rate in young, healthy men. The scale runs from 6 to 20. The idea was that if you multiply the RPE number by 10, you get an approximation of the athlete’s current heart rate (e.g., an RPE of 12 corresponds to roughly 120 bpm).
The “Why 6 to 20?” Question: The scale starts at 6 to represent a resting heart rate of approximately 60 bpm and ends at 20 for a maximum heart rate of around 200 bpm.
Limitations: The scale’s accuracy diminished when applied to different populations, such as children or older adults, whose heart rate responses to exercise differ. This limitation led to the development of a more versatile scale.
A Non-Linear Approach: The CR10 scale is the one most commonly used in modern training. It runs from 0 (nothing at all) to 10 (maximal exertion). Unlike the 6-20 scale, the CR10 scale is exponential. The perceived jump in effort from an RPE of 2 to 3 is much smaller than the jump from 8 to 9.
What it Measures: This scale correlates better with physiological markers that have a non-linear response to increasing intensity, such as:
Blood Lactate: Lactate levels remain relatively stable at low intensities and then rise exponentially as you cross your lactate threshold.
Pain: Similar to lactate, the sensation of pain during exercise increases dramatically at very high intensities.
Using the CR10 Scale Effectively:
Calibration is Key: An individual’s RPE is unique. An endurance ride might feel like a 2/10 for one person and a 5/10 for another, even if they are at the same physiological intensity (e.g., their first aerobic threshold, LT1). It’s crucial to “calibrate your brain” by consistently associating certain feelings with specific efforts (e.g., what a VO2 max interval feels like vs. a tempo interval).
Pain as a Guide: For very high-intensity efforts, using the sensation of pain can be a useful anchor. The pain of a 30-second all-out sprint is a higher “concentration” of pain than that of a 5-minute VO2 max interval. Recognizing these differences helps refine your RPE accuracy at the top end.
Objective data (power, heart rate) tells us what happened during a workout. Subjective feedback tells us why it happened and provides crucial context. This is the foundation of the coach-athlete feedback loop.
The Role of the “Master Gland”: The brain integrates countless internal and external signals (stress, sleep quality, nutrition, environment, motivation) to produce a given performance and a corresponding RPE. A coach, or a self-coached athlete, needs insight into these factors.
What Makes Good Feedback?: Simply saying a workout was “good” or “hard” is not enough. The podcast suggests providing context around several areas, especially if they deviated from the norm:
Nutrition & Hydration: Did you eat and drink enough before, during, and after?
Environment: Were you indoors or outdoors? Was it hot, humid, or cold?
Equipment: Did you use a different bike or power meter? A small change in bike fit can significantly alter muscle recruitment and fatigue.
Life Stress: How was your sleep? Are you stressed from work or family life?
RPE vs. Expectation: Did the workout feel harder or easier than prescribed? If so, the context above often provides the reason.
Consistency Over Time: Building a history of both objective data and subjective feedback allows you or your coach to see patterns, understand how you respond to different stressors, and make smarter training decisions.
Your body’s goal is to maintain a stable internal environment, a state known as homeostasis. Training is the act of deliberately disrupting this stability to provoke adaptation.
Homeostasis: This is your body’s baseline equilibrium. After a workout, your body initiates recovery processes (reducing inflammation, repairing muscle) to return to this state. If a training stimulus is not strong enough, you will simply recover back to your previous baseline without getting any fitter. In this case, “homeostasis wins.”
Allostasis: This is the process of achieving stability through change. When a training stress is significant enough, the body doesn’t just return to the old baseline; it adapts and creates a new, more robust one. This is the essence of getting fitter. Your body says, “That was stressful. I need to be better prepared for next time.” This results in physiological changes like:
Increased mitochondrial density
Increased capillary density
Improved VO2 max
The Plateau Problem: If you consistently apply the same training stress, your body will eventually fully adapt to it. At this point, the stimulus is no longer sufficient to disrupt homeostasis, and you stop improving. To continue adapting, you must introduce a new or greater stress (progressive overload).
Training for Adaptation:
A systematic review mentioned in the podcast confirms that all types of training—endurance, high-intensity intervals (HIIT), and sprint intervals (SIT)—are effective at stimulating adaptation.
For highly trained athletes, the stimulus must be more potent to continue driving adaptation. This is why HIIT and SIT become increasingly important for breaking through plateaus. However, this comes at the cost of greater fatigue, requiring more recovery.
The podcast touches on the relationship between the volume and intensity of exercise and overall health outcomes.
The J-Curve: This concept describes how health risk changes with exercise levels.
Sedentary: High risk of morbidity.
Moderate Exercise: As you begin to train, your health risk drops significantly, reaching the lowest point at the bottom of the “J.” The ACSM recommends at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity exercise per week, with more benefits seen up to 300 minutes of moderate exercise.
Very High Volume/Intensity: For athletes training significantly more than the general recommendations (e.g., 10+ hours per week), the health risk may begin to curve slightly upwards again, though the error bars in the data are wide. The risks are still far lower than being sedentary, but the acute risks associated with extreme endurance exercise (like atrial fibrillation or heart attacks during exercise) become a consideration.
Key Takeaway: The adaptations that make you a faster athlete are the same ones that improve your health. Consistency in training provides profound health benefits, regardless of your age, sex, or initial fitness level. Regular medical check-ups are advisable for anyone undertaking a strenuous exercise program.