Are you really doing HIIT or SIT? What are your ZONES?

Going from Intensity Zones to Heart Rate Zones

Exercise intensity zones are determined by the body’s metabolic response at a given intensity. This response is defined by the number of calories burned and the proportion of fats and carbohydrates used for energy. Measuring these variables requires metabolic analysis of expired oxygen and carbon dioxide. However, since metabolic testing isn’t feasible for every training session, heart rate is commonly used as a proxy metric to estimate metabolic response.

During a metabolic test, heart rate is correlated with metabolic states, allowing for the creation of personalized training zones. Since this correlation remains fairly constant, tracking heart rate during training can provide insights into metabolic responses without repeated metabolic testing.

How Different Are My Heart Rate Zones from Someone Else’s?

Heart rate zones are highly individual. While predictive equations and wearables attempt to estimate them, they can be inaccurate by up to 50%. Only metabolic testing can precisely determine personalized heart rate zones.

Do Training Zones Change Over Time?

Yes. Training and nutrition impact metabolism, altering how the body burns calories and the ratio of fat to carbohydrate utilization. As a result, heart rate zones change over time and should be reassessed regularly:

Every 6 months for individuals on a maintenance plan
Every 3 months for those progressing at a moderate pace
Every 4-8 weeks for athletes undergoing rigorous training

Training zones also vary depending on the type of exercise. For example, fat and carbohydrate usage at a given heart rate differ between running and cycling, affecting perceived exertion.

Training Zones and Physiological Adaptations

Each heart rate zone triggers different physiological benefits:

Zone 1: Active recovery, warm-up, and cooldown
Zone 2: Mitochondrial efficiency, fat-burning adaptation, endurance development, and metabolic health improvements
Zone 3: Pulmonary and cardiovascular strengthening, beneficial for individuals with heart or lung conditions
Zone 4: VO2max enhancement, improved lactate clearance, and higher-intensity endurance
Zone 5: Peak power and speed development, short bursts of high-intensity effort (60-120 seconds)

Key Takeaways

Personalized heart rate zones optimize training effectiveness.
Metabolic analysis is the most accurate method for determining training zones.
Exercise impacts multiple physiological systems and should be tailored to an individual’s fitness goals.
Training in the correct zone maximizes efficiency and prevents wasted effort.
Different forms of exercise (resistance, cardio, and interval training) should be incorporated into an individualized plan for optimal performance and health.

What is Interval Training?

Sprint Interval Training (SIT) and High-Intensity Interval Training (HIIT) are both structured approaches to improving metabolic efficiency, cardiovascular health, and mitochondrial function, but they differ in intensity, duration, and recovery periods.

Sprint Interval Training (SIT) vs. High-Intensity Interval Training (HIIT)

Sprint Interval Training (SIT):
- Short bursts (10-30 seconds) of all-out, supramaximal efforts (e.g., 150-200% of VO₂ max).
- Long recovery periods (minutes) to ensure full phosphagen recovery.
- Targeted toward anaerobic power, neuromuscular adaptations, and mitochondrial biogenesis.
- Effective for athletes needing speed, power, and metabolic flexibility (e.g., sprinters, endurance athletes, team sports).
High-Intensity Interval Training (HIIT):
- Intense work periods (30 seconds to several minutes) at 80-95% of VO₂ max.
- Recovery periods are shorter and may not allow full return to baseline.
- Enhances VO₂ max, lactate threshold, and metabolic efficiency through cardiovascular and mitochondrial adaptations.
- Used by endurance athletes, recreational exercisers, and those improving overall fitness.

Identifying, Measuring & Programming Intervals in PNOE Reports

In PNOE metabolic testing, we analyze oxygen consumption (VO₂), carbon dioxide production (VCO₂), and respiratory exchange ratio (RER) to determine the metabolic response to interval training.

Types of Intervals Based on Duration & Energy System Contribution:
- Short Intervals (10-30 sec, max effort) → ATP-PC system dominant
- Medium Intervals (30 sec – 3 min, 85-95% VO₂ max) → Glycolytic system dominant
- Long Intervals (3-10 min, 80-90% VO₂ max) → Aerobic-anaerobic transition zone

Key Metrics in PNOE Reports for Interval Design:
✅ VO₂ max & VO₂ kinetics – determines oxygen uptake efficiency and recovery needs.
✅ RER (Respiratory Exchange Ratio) – indicates carbohydrate vs. fat oxidation during intervals and recovery.
✅ Ventilatory Thresholds (VT1 & VT2) – identifies transition points for optimal interval prescription.
✅ Fat Max Testing – helps design base vs. interval training based on fat oxidation efficiency.

Rest-Based Interval Training & Zone 1 Recovery

The duration of recovery (time to return to Zone 1 or a low RER state) determines work-to-rest ratios.
If recovery to Zone 1 is slow, it indicates poor mitochondrial function, poor metabolic flexibility, or excess anaerobic reliance.
Rest-Based Interval Training Approach:
- Instead of fixed recovery time, athletes recover until their heart rate (HR), VO₂, or lactate levels return to baseline before the next effort.
- This ensures quality of effort rather than excessive fatigue accumulation.
- Helps improve mitochondrial function, fat oxidation, and aerobic efficiency.

Who Needs Interval Training? When to Start with Base Training?

Base Training First:

- Necessary for individuals with poor metabolic flexibility (low Fat Max, early shift to carb metabolism).
- Focus on Zone 2 training (60-75% VO₂ max) to build mitochondrial density and improve Fat Max.
- Goal: Improve ability to use fat as fuel before introducing high-intensity work.

When to Add Intervals?

- Once Fat Max and aerobic base are optimized, add intervals to improve anaerobic capacity, VO₂ max, and lactate threshold.
- Use HIIT (longer, sustained intervals) first, then SIT (max efforts) for speed & power gains.

Who Benefits from Interval Training?

✅ Endurance athletes needing higher VO₂ max, lactate clearance, and race-day speed.
✅ Athletes with plateaued Fat Max improvements (metabolic flexibility needed).
✅ Individuals with time constraints looking for metabolic efficiency gains in shorter sessions.

Mitochondria Function in Interval Training

Mitochondria are critical for energy production, fat oxidation, and endurance performance. Interval training influences mitochondrial function by:
Enhancing mitochondrial biogenesis (PGC-1α activation) – More mitochondria = greater ATP production & endurance.
Improving mitochondrial efficiency – Faster ATP resynthesis, better use of oxygen.
Boosting fat oxidation rates – Reduces reliance on carbohydrates at submaximal efforts.

PNOE: The Benefits of Individualized Exercise Programs

Metabolic Efficiency testing on the treadmill

Achieving fitness goals requires a structured exercise program that balances resistance, cardio, and interval training. VO2max testing provides the most precise exercise prescription by defining personalized training zones.

Exercise and Weight Management

Exercise plays a critical role in preventing disease, improving health, and supporting weight management.
While energy restriction is key to weight loss, exercise prevents metabolic adaptation, plateaus, and weight regain.
The American Heart Association (AHA) recommends at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week, alongside two days of resistance training.
An individualized exercise plan should include:
- Resistance training to build strength and muscle endurance.
- Cardio training to improve cardiovascular function.
- Interval training for metabolic efficiency and performance gains.

The Role of VO2max Testing

VO2max testing, or cardiopulmonary exercise testing (CPET), is the gold standard for determining individualized training zones. It establishes training zones based on:

Maximum heart rate (HRmax)
Anaerobic threshold (VT2), where the body shifts toward anaerobic metabolism

By leveraging metabolic analysis and individualized training plans, athletes and fitness enthusiasts can maximize efficiency, improve performance, and achieve their goals with precision.

1. Identifying Metabolic Health Issues

Metabolic dysfunction can manifest as:
✅ Poor energy production (fatigue, slow recovery)
✅ Low fat oxidation (carb dependency, bonking)
✅ Insulin resistance (poor glucose handling, cravings)
✅ Poor exercise tolerance (plateaued performance)
✅ Chronic inflammation (oxidative stress, aging signs)

Key Markers to Identify Issues

PNOE Metabolic Testing:
- VO₂ Max & Submax VO₂ → Aerobic efficiency
- Fat Max & RER (Respiratory Exchange Ratio) → Fat vs. carb utilization
- Ventilatory Thresholds (VT1 & VT2) → Metabolic flexibility, endurance
- Recovery Rate (HR & VO₂ kinetics) → Mitochondrial efficiency
Functional Lab Testing:
- Organic Acids Test (OAT) → Mitochondrial metabolites (ATP production)
- GI-MAP & Stool Testing → Gut-mitochondria connection, microbiome health
- DUTCH Test → Hormones impacting mitochondrial function (cortisol, DHEA)
- Metabolomics Panel → Cellular stress, inflammation, antioxidant status
Nutritional Therapy Assessments:
- Blood Sugar Control (CGM, fasting insulin, HbA1c)
- Amino Acid & Micronutrient Status (B vitamins, CoQ10, Magnesium)
- Fatty Acid Balance (Omega-3, Omega-6, phospholipid membrane health)

2. Solutions for Improving Mitochondrial Function & Metabolic Health

Biogenesis (New Mitochondria Formation)
✅ Zone 2 training (fat oxidation, PGC-1α activation)
✅ Strength training (mitochondrial density in muscle)
✅ Fasting & caloric restriction (stimulates AMPK & PGC-1α)
✅ Nutrients: Resveratrol, Berberine, PQQ, NMN

Mitophagy (Removing Dysfunctional Mitochondria)
✅ HIIT/Sprint Interval Training (SIT) (activates autophagy)
✅ Cold exposure (activates UCP-1, fat browning)
✅ Ketogenic strategies & fasting (increases autophagy)
✅ Polyphenols (quercetin, curcumin)

Function (Energy Production & ATP Generation)
✅ Targeted mitochondrial support (CoQ10, Alpha Lipoic Acid, L-Carnitine)
✅ Red light therapy (improves electron transport chain efficiency)
✅ Breathwork (enhances oxygen delivery to mitochondria)

Capacity (Maximizing ATP Output & Longevity Markers)
✅ VO₂ Max training (improves oxygen utilization)
✅ Sauna therapy (increases heat shock proteins)
✅ Hormesis (short-term stressors like fasting, cold exposure)
✅ Anti-inflammatory diet (reduces oxidative stress)

3. Creating a Personalized Program with PNOE Testing & Holistic Functional Health Approach

Using PNOE metabolic testing, we can tailor a bio-individualized plan:

Training Protocol (Based on PNOE Results)

Poor Fat Max? → Focus on Zone 2 aerobic training, metabolic flexibility drills
Low VO₂ Max? → Add HIIT & interval training to improve oxygen kinetics
Slow Recovery (HR & VO₂ kinetics)? → Improve mitochondria with cold therapy, deep sleep, and breathwork

Functional Nutrition & Supplementation

Lab Testing Shows Low Mitochondrial Markers?
- Fix gut health (probiotics, short-chain fatty acids, butyrate)
- Boost mitochondrial cofactors (Magnesium, B vitamins, CoQ10, ALA)
- Optimize blood sugar control (reduce insulin resistance, time meals around training)

Lifestyle & Recovery

Breathwork & HRV Tracking (improves parasympathetic tone)
Sleep Optimization (deep sleep = mitochondrial repair)
Cold & Heat Exposure (mitochondrial biogenesis, resilience)

4. Debbie Potts’ Holistic Coaching Approach

Debbie integrates PNOE data, functional labs, nutrition, and lifestyle coaching to optimize metabolic health, mitochondria, and longevity.

✅ Metabolic Investigations – Finding & fixing hidden stressors (gut, toxins, glucose regulation)
✅ Personalized Training – Structuring base training, interval work, and recovery zones
✅ Nutrition & Biohacking – Aligning macro/micronutrients, fasting, mitochondrial support
✅ The WHOLESTIC Method – Addressing stress, sleep, gut health, movement, and mindset

Test, Don’t Guess: How PNOE & Functional Lab Testing Optimize Your Training & Metabolic Health

To personalize training & nutrition, we need data from PNOE metabolic testing, functional lab testing, and nutritional therapy assessments. This holistic approach helps optimize mitochondrial function, metabolic flexibility, recovery, and longevity.

1️⃣ PNOE Metabolic Testing: Identifying Your Training Needs

PNOE measures:
✅ Fat Max & Carb Utilization → Are you efficient at burning fat?
✅ VO₂ Max & Aerobic Thresholds (VT1 & VT2) → Is your endurance or power limiting you?
✅ Mitochondrial Efficiency → Do you fatigue quickly or recover slowly?
✅ Lactate Clearance & Recovery Time → Do you struggle with high-intensity work?
✅ Ventilatory Efficiency (Breathing Mechanics) → Do you need respiratory training?

PNOE Results & Training Recommendations:

Finding	Issue	Solution
Low Fat Max (Poor Fat Burning)	Metabolic inflexibility, carb dependency	Zone 2 training, mitochondrial support
Low VO₂ Max	Poor endurance, early fatigue	HIIT 1-2x/week
Weak VT2 (Poor High-Intensity Tolerance)	Can’t sustain efforts, early burnout	HIIT + SIT for anaerobic capacity
Slow Recovery Time (High RER at Rest)	Poor mitochondrial function, chronic stress	More Zone 2, breathwork, HRV tracking
Poor Breathing Mechanics	Inefficient oxygen use, high RER	Respiratory training (diaphragmatic work)

2️⃣ Functional Lab Testing: Digging Deeper into Metabolism & Recovery

While PNOE identifies real-time metabolic inefficiencies, functional lab testing uncovers internal dysfunctions affecting energy production, fat loss, recovery, and longevity.

Key Functional Labs & What They Tell Us

Test	What It Measures	Impact on Training & Metabolic Health
GI MAP (Gut Test)	Microbiome health, inflammation, pathogens	Poor gut health = impaired nutrient absorption & performance
Organic Acids Test (OAT)	Mitochondrial function, energy production	Low ATP = fatigue, poor endurance
DUTCH Hormone Test	Cortisol, DHEA, sex hormones	High cortisol = poor recovery & fat storage
Metabolomics Panel	Cellular metabolism, oxidative stress	Poor metabolic function = low endurance & slow recovery
Micronutrient Panel	Vitamin & mineral status	Deficiencies = reduced mitochondrial efficiency

3️⃣ How Mitochondrial Function Affects Training & Longevity

Mitochondria are the powerhouses of your cells, and their efficiency determines:
Fat oxidation & endurance (Zone 2 training improves mitochondrial biogenesis)
Explosive power (SIT stimulates ATP production & mitochondrial adaptation)
Recovery & longevity (Mitophagy clears out damaged mitochondria)

Mitochondrial Testing Markers:
✅ Low VO₂ Max on PNOE → Mitochondrial dysfunction
✅ Elevated lactate post-exercise → Poor clearance, inefficient energy production
✅ Low CoQ10, B vitamins, magnesium (from lab tests) → Poor mitochondrial ATP output
✅ Chronic fatigue & slow recovery → Mitochondrial dysfunction & oxidative stress

Interventions to Improve Mitochondria:

Zone 2 training → Mitochondrial biogenesis
SIT (Sprint Training) → Stimulates mitophagy (removes damaged mitochondria)
Cold exposure (55-56°F) → Boosts mitochondrial efficiency
Red light therapy → Supports ATP production
Nutritional support → CoQ10, magnesium, B vitamins, PQQ

4️⃣ Creating a Personalized Plan (PNOE + Functional Testing + Nutrition)

Step 1: Test Metabolism & Health
PNOE Metabolic Test → Identify Fat Max, VO₂ Max, recovery, thresholds
Functional Lab Tests → Mitochondria, hormones, gut health, nutrients

Step 2: Design Training Plan
️‍♂️ Zone 2 focus if metabolic inflexibility, poor fat oxidation
⚡ HIIT/SIT if VO₂ Max is low or power output needs improvement
Recovery tracking (HRV, breathwork, sleep optimization)

Step 3: Address Deficiencies
️ Personalized Nutrition & Supplement Plan → Based on lab test results
Gut health support if nutrient absorption is impaired
Mitochondrial boosters (cold exposure, light therapy, fasting)

Final Takeaway: How to Know What YOU Need

✅ Start with PNOE Testing → Get metabolic data
✅ Run Functional Labs → Address underlying health issues
✅ Build a personalized plan with nutrition, training, and recovery strategies

Want help designing a program using PNOE + functional testing? Let’s create a customized metabolic optimization plan!