Metabolic Mastery

Most fitness advice was written for the “average body,” and nobody is average from head to toe. In this episode of Metabolic Mastery, hosts Dr. Marc Humbert and Dr. Cameron Garber sit down with Michael Kamalu, founder of Dr. Gains, to explain why generic workouts fail and what truly personalized training looks like.

Michael shares his path from a skinny eighth-grade basketball player with a string of injuries to Mayo Clinic Medical School, and how that led him to build tools and a facility around one idea: your training should match your anatomy, your metabolism, your goals, and your constraints.

They cover how body proportions and even the number of lumbar vertebrae change how you should lift, why the “best” recovery tool depends on your goal, and how diagnostics like metabolic testing can feed a plan built for you. They also get into blood flow restriction training, rotational loading, and why muscles grow unevenly.

You Will Learn:

• Why generic fitness advice is written for the “average body,” and how anatomical variations (like having four, five, or six lumbar vertebrae) change how you should squat and lift
• How limb proportions affect the load your muscles actually feel, and why comparing lifts between two people can mislead you
• Why the same recovery tool can help one goal and hurt another, such as a cold plunge after training helping strength but potentially blunting muscle growth
• How metabolic testing, muscle function testing, and other diagnostics can combine into one personalized plan instead of ten disconnected opinions
• Why “perfect” training and recovery plans fail if they don’t fit your life, your timeline, and your constraints
• How blood flow restriction (BFR) training lets you build size, strength, and endurance with lighter weights, and why measuring arterial occlusion pressure matters
• Why rotational training is missing from most routines, and how it ties to rotator cuff health and injury prevention
• How regional muscle activation works, and why varying your exercises prevents weak points and injuries
• Why muscles adapt faster than tendons and joint capsules, and how to train for long-term resilience instead of short-term gains

Get A Demo: https://korr.com/contact/video-demo/

Metabolic testing can feel overwhelming, but it starts with just four measurements.

In this episode of Metabolic Mastery, hosts Dr. Marc Humbert and Dr. Cameron Garber walk through how the cardio coach turns oxygen, carbon dioxide, flow, and heart rate into a deep physiological picture.

They sort that data into tiers of reliability, from directly measured values to estimates, and explain how to troubleshoot a test that looks “wrong.” Then they bring it back to simplicity: how to turn complex results into small, sustainable changes that fit a client’s real life, using frameworks like the aggregation of marginal gains and frequency, duration, then intensity.

You Will Learn:

• The four core measurements behind every test (O2, CO2, flow, and heart rate) and how they produce dozens of outputs
• Why a fixed-orifice differential pneumotach with no moving parts keeps flow measurement accurate without constant recalibration
• The tiers of data reliability: measured values, calculated values, values using known constants, estimates, thresholds, and normative comparisons
• Why a measured RMR beats predictive equations, which can be off by 200-400 calories either way
• Why “the numbers have to be wrong” is usually a setup, protocol, or client-prep issue, and the fasted, rested, unstimulated rule of thumb for reliable baselines
• How aerobic and anaerobic thresholds are frameworks applied to real physiological inflection points, not single measured values
• Why a high VO2 max that is dropping can be a worse sign than a lower one that is climbing, using a real client example
• How to turn complex data into a simple plan with the aggregation of marginal gains and the “90% confidence” test for any new habit
• Why to build frequency first, then duration, then intensity, and how to meet each client where they are

Get A Demo: https://korr.com/contact/video-demo/

Heart rate zones might be the most misunderstood concept in fitness — and in this episode of Metabolic Mastery, hosts Dr. Marc Humbert and Dr. Cameron Garber take a deep dive into exactly why.

From elite Olympic athletes using completely different zone systems to say the same thing, to the century-old misunderstanding behind "anaerobic threshold," they break down how heart rate zones are actually derived, why physiology is a continuum rather than an on/off switch, and how to use testing data (not guesswork or wearable estimates) to train for the adaptations that actually matter.

You Will Learn:

• Why "zone 2" means something completely different depending on whether you're using a 3-zone, 4-zone, or 5-zone system — and why that causes so much confusion online
• The real story behind "aerobic" and "anaerobic" thresholds, and why lactate is actually produced continuously, even aerobically
• Why percentage-based zoning (like 220-minus-age or % of VO2 max) can lead to large individual errors compared to physiology-based zoning
• Why wearable VO2 max estimates are a "prediction of a prediction" and can mislead you about your actual fitness
• Why zone 3 is often "the no-progress zone" — hard enough to require recovery, but not hard enough to drive real adaptation
• The specific physiological adaptations happening in each zone: capillarization and mitochondrial density in zone 1-2, cardiac output improvements, and top-end power and mitochondrial efficiency in zones 4-5
• Why consistency (not intensity) is the real driver of long-term change, and how training every day — even lightly — beats sporadic hard efforts
• The difference between performance and resilience, and why "surviving" a training program doesn't mean it was optimal
• How to use RPE, pace, and power as anchors to your heart rate zones for better self-awareness and auto-regulation

Get A Demo: https://korr.com/contact/video-demo/

Dr. Craig Broeder has spent 45 years at the top of exercise physiology and metabolic testing, training under legends like Jack Wilmore, David Costill, and George Brooks, running biopsy-heavy research trials, and leading elite performance projects for Red Bull's world-class athletes.

In this episode of Metabolic Mastery, hosts Dr. Marc Humbert and Dr. Cameron Garber sit down with Dr. Broeder to unpack decades of hard-won lessons on what separates accurate metabolic testing from guesswork, from calibration pitfalls to genetic limits on VO2 max, and why so many popular fitness devices get it dangerously wrong.

You Will Learn:

• How Dr. Broeder's path from professional musician to exercise physiologist began, and the mentors (Wilmore, Costill, Ivy, Coyle) who shaped his career
• Why mixing chamber, breath-by-breath, and mini mixing chamber metabolic systems each have unique strengths and blind spots
• The real-world calibration mistakes (temperature, humidity, drying lines) that silently corrupt test data
• Shocking accuracy findings from a published Cardio Coach validation study — including one popular consumer system with error rates up to 16.9%
• Inside the Heritage Project: what large-scale genetic research reveals about how much of your VO2 max improvement is really genetics vs. training
• Behind-the-scenes stories from Red Bull's altitude performance research with elite cyclists and runners
• Why knowing a client's history, goals, and psychological comfort with testing is just as important as the protocol itself
• How Dr. Broeder used metabolic testing to help a client recover from a severely underfed metabolism (800 to 1,290 calories) without weight-loss drugs

Get Daniel's PTAP Course: https://strategichealthperformance.inspire360.com/p/ptap-foundations

Get A Demo: https://korr.com/contact/video-demo/

Most people buying a metabolic analyzer have no idea how much data they're leaving on the table. In this episode of Metabolic Mastery, hosts Dr. Marc Humbert and Dr. Cameron Garber sit down with Daniel Crumback, KORR's Director of International Sales and a certified exercise physiologist, chartered physiotherapist, and strength and conditioning specialist with 30 years of testing experience, to break down how to get the absolute most out of your cardio coach.

They cover why VO2 max alone only tells half the story, the hidden difference between metabolic and ventilatory zoning methods, the testing mistakes that quietly wreck your data, and why retesting (not just testing) is where the real transformation happens.

You Will Learn:

• Why VO2 max is just "the sexy thing to sell", and what data actually drives real programming decisions
• The critical difference between metabolic (RER-based) and ventilatory (VE/VO2, VE/VCO2) zoning methods, and why they can produce zones 20-30 beats apart
• How to identify a client's true physiological limiter (cardiovascular, respiratory, or metabolic) and zone accordingly
• Why "peak" and "max" aren't the same thing, and how missing a true max (RER of 1.15+) leaves critical zone-five data off the table
• The proper testing protocol: a 5-minute low-intensity warm-up, correctly sized increments, and tests lasting 9-12 minutes
• Why RMR and VO2 max testing should never be done in isolation from each other
• How VO2 pulse and peak VO2/breathing frequency can reveal undiagnosed cardiac and respiratory issues
• Why retesting, not a one-and-done test, is what truly drives client retention and long-term results
• How mismatched fat/carb utilization at rest vs. during exercise points directly to nutrition issues

Get A Demo: https://korr.com/contact/video-demo/

Dr. Thomas George didn't set out to become an obesity medicine specialist — a traumatic brain injury and a 120-pound weight gain got him there. In this episode of Metabolic Mastery, Dr. Mark Humbert and Dr. Cameron Garber sit down with Dr. George, founder of Wellspring Weight and Wellness, to unpack the science and story behind sustainable weight management.

Dr. George shares his own journey from competitive martial artist to 330 pounds and back, and how a neuroendocrinologist's diagnosis changed the way he sees — and treats — obesity. The conversation dives deep into adipocyte biology, why "it's not about the weight," the real data behind adaptive thermogenesis, and why so many patients on GLP-1 medications still hit frustrating plateaus.

You Will Learn:

• Why obesity is best understood as a "disease of diseases" and what that means for treatment
• How the personal fat threshold and adipocyte hypertrophy drive metabolic dysfunction
• What resting energy expenditure testing reveals about adaptive thermogenesis — and why its effects can persist up to six years
• Why GLP-1/GIP medications don't fix metabolism on their own, and what's missing from many prescribing plans
• How building metabolically healthy muscle protects against weight regain and sarcopenia
• Why exercise matters more for maintenance than for initial weight loss
• How cultural food patterns (Mediterranean, Inuit, Hispanic heritage diets) inform sustainable eating
• Why calorie quality, density, and dosage matter more than any single "diet"

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Get A Demo: https://korr.com/contact/video-demo/

Should every client do a warm-up before a VO2 max test? In this episode of Metabolic Mastery, Dr. Marc Humbert and Dr. Cameron Garber tackle a question that's surprisingly underexplored in the exercise science literature: how to properly warm up a client before metabolic testing.

They break down the three main purposes of a warm-up — transition, familiarization, and priming — and introduce their practical R.E.A.D.Y. framework to help practitioners decide exactly how much (or how little) warm-up a given client needs. From elite athletes to deconditioned beginners, from ramp protocols to fat max testing, Marc and Cameron walk through real-world scenarios, mask familiarization tips, and how to use heart rate as a readiness indicator before you ever hit "start" on the test.

You Will Learn:

• The three primary purposes of a warm-up: transition, familiarization, and priming
• Why "it depends" is the right answer for whether a client needs a warm-up
• The R.E.A.D.Y. framework: Reason, Estimate, Acclimate, Dose, and confirming they're ready
• How to use heart rate stability as a signal that a client is ready to begin testing
• Why building the warm-up into the protocol can save time without sacrificing data quality
• Tips for helping clients get comfortable with the mask and equipment before testing starts
• How to document warm-up protocols in Cardio Coach software for consistent repeat testing
• When elite athletes need a separate warm-up vs. when to skip it for deconditioned clients

Get A Demo: https://korr.com/contact/video-demo/

On this episode of Metabolic Mastery, hosts Dr. Marc Humbert and Dr. Cameron Garber are joined by Jody Nelson — KORR's resident metabolic testing expert with a decade of experience and a degree in exercise science — to break down a real client case study.

The client: an otherwise fit woman, 18 months postpartum, doing everything "right" — solid nutrition, consistent low-intensity walking — yet stuck in a frustrating weight loss plateau. Her VO2 max test revealed something unexpected: a surprisingly narrow fat-burning zone, a rapid heart rate spike when transitioning from walking to running, and a respiratory pattern that told a much bigger story than the numbers alone.

Marc, Cameron, and Jody walk through the respiratory rate and tidal volume graphs in real time, showing how early-test hyperventilation and anxiety can skew substrate utilization data — and why the device is almost never "wrong." They dig into the difference between being fit and being healthy, why perceived exertion is an unreliable guide, and how major hormonal shifts (postpartum, pregnancy, menopause) can scramble a client's ability to accurately read their own body.

You Will Learn:

• Why a narrow fat-burning zone doesn't always mean poor metabolic health — and what else could be going on
• How to read respiratory rate and tidal volume graphs to spot hyperventilation and test anxiety
• Why "the device is broken" is almost never the right conclusion when a test result looks unusual
• The critical difference between being cardiovascularly fit and being metabolically/physically healthy
• Why perceived exertion is an unreliable training guide and how heart rate data corrects it
• How hormonal changes during postpartum, pregnancy, and menopause affect metabolic test results
• Why testing what you intend to measure (and training for the adaptations you want) matters
• How to ask better follow-up questions instead of jumping to blood work or invasive testing
• Why "fit" doesn't always mean "healthy" — and what that means for injury risk and longevity

Get A Demo: https://korr.com/contact/video-demo/

In part two of this two-part series, Metabolic Mastery hosts Dr. Marc Humbert and Dr. Cameron Garber shift gears from low intensity training to high intensity — breaking down exactly what HIIT does physiologically, why it works, and how to design intervals that actually match your goals.

They start by revisiting the "three zone" model (comfortable, comfortably uncomfortable, and uncomfortable) and explain why moderate intensity — the "no progress zone" — often doesn't drive much adaptation for people who already live there. From there, they dig into the real benefits of high intensity work: rapid VO2 max improvements, stronger cardiovascular pumping, better lactate shuttling, and improved top-end speed and power.

A major focus of this episode is debunking the lactic acid myth — lactate isn't a waste product causing muscle burn, it's a valuable fuel source, and understanding how it's produced, transported, and used is key to designing smarter workouts. Marc and Cameron also walk through the "three dials" (oxidative, glycolytic, neuromuscular) and "three clocks" (time under load, interval length, recovery time) framework for designing HIIT workouts with intention — plus why heart rate alone isn't a reliable guide at high intensities, and how VO2 max testing data can pinpoint the exact speed or power to target for real adaptation.

You Will Learn:

• The difference between "comfortable," "comfortably uncomfortable," and "uncomfortable" training zones — and why the middle zone often delivers the least return
• Why lactate is a fuel source, not a fatigue-causing waste product — and how the body actually clears and uses it
• The real benefits of high intensity interval training, including rapid VO2 max gains and improved mitochondrial efficiency
• How to use the "three dials" (oxidative, glycolytic, neuromuscular) to design intervals for specific adaptations
• Why heart rate lags at high intensity and why speed/power targets (from VO2 max testing) are more reliable
• How interval length and recovery time change which energy systems you're actually training
• Why "short term hard, long term easy" beats chasing quick fixes when it comes to fitness and health
• How to avoid junk volume by matching your training to your actual physiology instead of generic templates
• The difference between HIIT-style intervals and longer threshold work — and when to use each

Get A Demo:https://korr.com/contact/video-demo/

Is Zone 2 training the answer or should you spend your limited workout time doing high-intensity intervals? The research can make almost any popular workout sound like the best option, but that advice often overlooks the most important variable: the individual doing the training.

In this episode of Metabolic Mastery, Dr. Marc Humbert and Dr. Cameron Garber explain why effective exercise prescription begins with your goals, physiology, injury history, available time, recovery capacity, and current fitness. They break down how the body’s energy systems work together, why heart rate zone terminology creates confusion, and how social media can turn narrow research findings into sweeping recommendations.

You’ll also learn how frequency, duration, and intensity shape an effective training plan; why progressive overload must be balanced with recovery; and what low-intensity exercise uniquely contributes to aerobic capacity, mitochondrial function, and consistency. Marc and Cameron also discuss how metabolic testing with CardioCoach can provide individualized data for selecting the training methods most relevant to a person’s needs.

The goal is not to choose the winning exercise camp. It is to find the right combination—and the right dose—for the person in front of you.

• Why there is no single best workout for every person or goal
• How goals, time, recovery, and injury history influence exercise selection
• Why the body’s energy systems behave more like dials than switches
• What different heart rate zone models mean when they refer to “Zone 2”
• How social media can overgeneralize narrowly focused exercise research
• Why frequency and duration often matter before increasing intensity
• How progressive overload drives adaptation—and when training becomes too much
• What low-intensity exercise does for aerobic metabolism and mitochondrial function
• Why moderate-intensity training may produce fewer new adaptations for some people
• How metabolic testing can support a more personalized exercise prescription

00:00 Is there a best workout?
02:23 Why popular workouts become universal recommendations
04:45 Building a personalized exercise prescription
07:00 Energy systems work together
09:28 How the body uses different fuels
11:55 Matching energy systems to your goals
14:18 Why “Zone 2” can mean different things
16:34 What HIIT research does—and does not—tell us
18:55 Frequency, duration, and intensity
21:19 How your training history changes your starting point
23:36 Looking beyond fitness advice on social media
26:02 Adapting exercise to individual limitations
30:43 Treating exercise like a precise prescription
32:59 Specific adaptation and progressive overload
35:08 Finding the right training dose
37:31 The benefits of low-intensity exercise
39:49 Volume, adaptation, and injury risk
42:08 Balancing training stimulus with recovery
44:34 The limitations of moderate-intensity training
46:59 Choosing intensity based on time and goals
49:23 Progressing from walking to higher intensity
51:49 Using individualized data to guide training
54:11 Stop choosing camps and start choosing the right dose