Flex Diet Podcast

James de Lacey is a strength and conditioning coach with an MSc in Sport & Exercise Science and more than a decade of experience in professional sport spanning professional and international rugby/rugby league. He now focuses on combat sports to prepare fighters under Sweet Science of Fighting.

Do fighters really need zone 2 cardio? Strength and conditioning coach James de Lacey of Sweet Science of Fighting joins Dr. Mike T Nelson to challenge the "big aerobic base first" playbook for combat sports, from heart rate recovery and short-rest sprint intervals to muscle oxygen (NIRS) data. They also dig into VO2 max, wearables and why AI-written programs often miss the mark.

Expect to learn why James questions the “huge aerobic base” approach for fighters, how heart rate recovery and heart rate kinetics can reveal more than time in zones, how short-rest sprint intervals and a simple air bike baseline test can guide programming, what muscle oxygen (NIRS) data can and can’t tell you, why trends beat single data points from wearables, and why generic AI-written programs often miss the mark—and much more.

Connect with James:

• sweetscienceoffighting.com
• jamesdelacey.com
• Sweet Science of Fighting on Instagram
• Sweet Science of Fighting on YouTube

Episodes you'll enjoy next:

• Episode 326: Row Hard, Breathe Easy: Boosting Aerobic Capacity with Dr. Kenneth Jay: Dr. Kenneth Jay on rowing and boosting aerobic capacity (Mike credits Dr. Jay for the bioenergetic testing he mentions in this conversation).
• Episode 221: Training performance, nitric oxide, blood flow, and more via the NNOXX device with Evan Peikon: Evan Peikon on training performance, nitric oxide and blood flow via the NNOXX device (Mike mentions Evan in this conversation).

Episode Timestamps:

•  03:35 The biggest conditioning mistake in MMA
• 05:50 Why sprints are more aerobic than you think
• 07:46 Do fighters need a huge aerobic base?
• 09:44 VO2 max, muscle limits and oxygen testing
• 11:57 Conditioning trends and training volume
• 15:36 Zone 2, time costs and the 80/20 debate
• 22:10 Heart rate response and recovery between rounds
• 25:43 Mike’s rower test and heart rate recovery
• 28:25 Air bike sprints with short rests
• 31:44 Muscle oxygen and power between repeats
• 34:19 Testing and training each athlete’s limiter
• 41:47 Flexible Meathead Cardio and technical training
• 46:05 Elite athletes, VO2 max and training context
• 50:22 NIRS, oxygen drops and peak power
• 57:18 Why trends beat single test results
• 1:02:56 Wearables, coaching judgment and session design
• 1:06:57 AI programs and generic training blocks
• 1:13:02 Training around life and where to find James

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Bryan Krahn has been a personal trainer since 1997, a CSCS since 2005, and a full-time online coach since 2014. He is a fitness writer and the author of two books with Men's Health.

Will AI replace online coaches, or only the ones who stop being human? Veteran online coach and Men's Health author Bryan Krahn joins Dr. Mike T Nelson for a candid, unfiltered conversation about paying for expertise, whether coaches should disclose AI use, personal experiences with peptides and TRT (opinion, not advice), and Mike's simple rower-based cardio plan.

Expect to learn why paying for expertise makes you a better coach, how Bryan and Mike use (and distrust) AI in coaching and writing, whether coaches should disclose their AI use, why stacking compounds makes personal experiments hard to interpret, how Bryan thinks about TRT and lab markers like HDL, LDL and PSA, and Mike’s simple rower-based cardio plan—and much more.

Bryan and Mike discuss peptides, TRT and other compounds from personal experience and opinion. Nothing here is medical advice; talk to a qualified healthcare professional before changing any medication or supplement routine.

Connect with Bryan:

• over50muscle.com
• Bryan on Instagram (@bryankrahn)

Episodes you'll enjoy next:

• Episode 137: Training Straight Talk with fitness writer, and online physique coach Bryan Krahn: Bryan's previous visit to the show: training straight talk from a fitness writer and online physique coach.
• AI Disclosure, Deepfakes & the Death of Expertise — Dean Guedo & Jeb Stuart Johnston — #404: Dean Guedo and Jeb Stuart Johnston on AI disclosure, deepfakes and the death of expertise (Mike mentions Dean in this conversation).

Episode Timestamps:

• 02:25 Online coaching's catch-22: taking clients you may not be set up to help
• 04:16 Bryan's niche: from over-40 clients to the over-50 guy, and why parents and older dads fit
• 06:10 Edge-case clients, referral networks and paying peers for expertise
• 08:06 Why paying for consults still matters, including Bryan's 1999 consult with Charles Poliquin
• 11:35 Why AI still struggles with niche training questions: PEDs, zone two and the Thomas Inch dumbbell
• 17:03 AI inside coaching software, and why chatbots are so agreeable
• 18:53 Would clients be accountable to a bot, and will live coaches last?
• 23:48 Should coaches disclose AI use to clients? Everyday AI wins like soundbars and grill repair
• 27:29 Contest-prep coaches, AI photo checks, and why coaches get second opinions
• 34:32 Peptide offers and appetite-suppressing drugs: personal experiences, not advice
• 39:38 DNP stories and risks as the speakers recount them
• 42:34 Mitochondrial peptides, NAD+ and IV infusions: why stacked self-experiments are hard to interpret
• 49:39 TRT: dialing in the basics first and working with a physician
• 52:41 Lab markers: HDL, LDL and PSA, and changing the marker versus the outcome
• 58:37 Traveling with a TRT prescription: Bryan's border-security story
• 1:01:25 Mike's rower cardio plan: baseline 2K test, progressive six-minute sessions and a smarter four-by-four
• 1:10:58 Should writers disclose AI use? Beating the blank page without losing your voice
• 1:19:06 Wrap-up: coaching availability, training from 50 to 53, and where to find Bryan

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Dr. Gregory Kelly, N.D., is Chief Product Officer at Qualia Life, a naturopathic physician, author of Shape Shift, and former editor of Alternative Medicine Review.

Detox is more than a liver story—and it is not a juice cleanse. Dr. Gregory Kelly of Qualia Life explains how clearance pathways work together, why mobilizing stored chemicals is not the same as eliminating them, and the thinking behind Qualia 2-Day Detox.

Expect to learn why detox skepticism is warranted, how Dr. Kelly thinks about cumulative stress and chemical exposure, what liver biotransformation and elimination mean, why his formulation includes a between-meals binder stack, how sleep and the glymphatic system enter the conversation, and what Qualia’s small symptom-questionnaire study can and cannot establish—and much more.

Dr. Kelly discusses his company’s Qualia 2-Day Detox product. Product descriptions and health claims are his views, not independent verification or medical advice; the small study discussed used self-reported symptom questionnaires.

Connect with Greg:

• Qualia on Facebook
• Qualia on Instagram
• Qualia on TikTok
• Dr. Gregory Kelly on LinkedIn

Episodes you'll enjoy next:

• Episode 352: Dr. Dan Pardi on Stem Cells, Supplements, and the Future of Health with Qualia: Dr. Dan Pardi on stem cells, supplements, cognitive performance and health habits at Qualia.
• Episode 310: Unpacking the Science of Sleep with Dr. Allison Brager: Neuroscientist Dr. Allison Brager on sleep phases, circadian rhythms and performance.

Episode Timestamps:

• 05:03 Detox skepticism and why this conversation matters
• 06:35 Why Qualia chose to develop a detox product, according to Dr. Kelly
• 08:08 Who might need detox support, and Mike's experience with wildfire air pollution
• 09:42 Dr. Kelly's environmental medicine background and the "last straw" bucket analogy for stress load
• 12:44 Exposures Dr. Kelly tries to limit: canned foods, strong scents, new furniture, indoor air
• 15:59 Small, consistent changes versus one silver bullet; Dr. Kelly cites biomonitoring studies
• 18:59 Water filtration and drinking-water habits
• 21:32 Larger exposures, the precautionary principle, mold, and skin products
• 24:18 Sunscreen, sun exposure, and not overcomplicating health choices
• 28:39 How Qualia approached the formulation, and an explanation of phase one, two, and three liver pathways
• 33:07 Dr. Kelly's description of the four-step packets: morning and with-meal
• 36:28 The between-meals binder stack, and a weight-loss study Dr. Kelly cites on stored chemicals
• 40:26 The bedtime packet, the glymphatic system, and brain demands when learning new skills
• 44:35 Fat-loss phases, a two-days-a-month approach, and Qualia's small symptom-questionnaire study
• 48:49 Dr. Kelly's pairings for detox days: sauna, gentle movement, hydration, skin brushing, baths
• 54:24 Wrap-up: fitting the routine into your schedule, and where to find more information

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In this episode of the Flex Diet Podcast, I break down why I built the Physiologic Flexibility Certification (PhysFlex) as a “level two” continuation after you’ve already got the basics of nutrition, training, and recovery mostly dialed in.  I explain how Phys Flex targets four overlapping homeostatic regulators—temperature (heat/cold exposure), pH (acidity/alkalinity shifts), expanded fuels (ketones and lactate), and oxygen/CO2 regulation (breathing)—and why taking a systems view matters more than treating everything in silos. 

I share examples of how these pillars can become the real limiter in recovery and performance, including high-intensity work, long-duration events, and signs like elevated overnight respiration rate. Enrollment is open from Monday, October 12 through midnight PST Monday, October 19, 2026, and I’m offering direct email access for questions.

Enroll here: https://physiologic.miketnelson.com/sales

Episode Timestamps:

• 00:00 Welcome and Podcast Focus
• 00:19 Course Enrollment Window
• 01:44 Who This Certification Is For
• 02:48 Why Four Pillars Together
• 03:41 The Four Homeostatic Pillars
• 05:05 Systems Thinking Over Silos
• 08:07 Applying the Framework to Recovery
• 11:41 Course Structure and Interventions
• 13:09 Support, Email Access, Next Guest
• 13:58 Medical Disclaimer and Closing

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Dr. Jordan Shallow, D.C., known as “The Muscle Doc,” is a chiropractor, strength and conditioning coach, and former competitive powerlifter. He is the founder of Pre-Script®, an education company that teaches coaches applied biomechanics and resistance training.

Is getting stronger really about muscle, or about how well your nervous system learns the lift? Dr. Jordan Shallow, “The Muscle Doc,” explains why strength and size follow skill, how your senses shape movement, and how simple sensory inputs may change the way you train.

Expect to learn when internal versus external cues make sense for strength and hypertrophy, how an intermediate lifter can use practice volume and frequency, why great lifters treat the empty bar like the heavy one, how touch, vibration, skin stretch and pressure may influence movement, and how neuroplasticity, lucid dreaming and film study connect to learning skills — and much more.

Connect with Jordan:

• Website: themuscledoc.com
• Pre-Script: pre-script.com
• Instagram: @the_muscle_doc
• Pre-Script on Instagram: @pre_script

Episodes you'll enjoy next:

• #401 — Psychedelics, Neuroplasticity and the Military-to-Spiritual Journey with Rick Alexander: A former Special Operations combat medic explains how a psychedelic experience reshaped his worldview, and what it taught him about neuroplasticity.
• #311 — Maximizing Athletic Performance with Neurology: Insights from Dr. Dylan Seeley: Dr. Dylan Seeley on how applying neurology can improve athletic performance.

Episode Timestamps:

• 03:47 Internal vs. external cues for strength and hypertrophy
• 06:24 Longevity culture and why skill comes before loading
• 09:58 Intermediate bench press case study: practice volume and frequency
• 17:34 Ed Coan, intent and moving the empty bar like the heavy bar
• 23:30 Sensory-motor savants: Tiger Woods, Nick Kyrgios and Brian Shaw
• 27:29 How trainable is the sensory system?
• 29:35 Foam rollers, kinesio tape and cupping through a neurological lens
• 32:10 Perception, the electromagnetic spectrum and the limits of our senses
• 36:23 Mechanoreceptors and vibration
• 41:05 Light touch, vibration, skin stretch and deep pressure
• 47:14 Fast feedback: testing and iterating with the nervous system
• 51:38 Neuroplasticity, psychedelics and learning skills faster
• 1:02:45 Reality Switch Technology, tropanes and perception
• 1:05:08 Dreams, hypnagogic hallucinations and altered perception
• 1:12:26 Lucid dreaming and practicing the deadlift without the load
• 1:23:19 Film study, muscle memory and watching good reps
• 1:26:37 Where to find Dr. Jordan Shallow

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Dr. Martin Gibala is a Professor of Kinesiology at McMaster University and one of the world's leading researchers on high-intensity interval training.

Can short bursts of hard cardio outperform hours of Zone 2 for the average person? Exercise physiologist Dr. Martin Gibala explains how HIIT can improve VO2 max and metabolic flexibility, why elite athletes' 80/20 split may not fit a time-strapped schedule, and how to judge vigorous effort without chasing a perfect heart-rate zone.

Expect to learn how to scale HIIT for beginners, what RPE and the talk test reveal about vigorous effort, when short sprints differ from VO2 max intervals, why elite athletes’ 80/20 approach may not fit your schedule, how Zone 2 definitions can mislead, and what metabolic flexibility and mitochondrial capacity really mean—and much more.

Connect with Martin:

• Website: martingibala.com
• X: @gibalam
• Book: The One-Minute Workout (Avery, 2017; with Christopher Shulgan)
• Podcast: Exercise Science

Episodes you'll enjoy next:

• #402 — VO2 Max, Zone 2 Training & the Psychology of Human Performance — Ben Skutnik: Dr. Ben Skutnik cuts through Zone 2 hype and discusses VO2 max and aerobic-training evidence.
• #387 — Nathan T. Jenkins on Metabolic Flexibility, Aerobic Base, and First Principles: a look at aerobic development, energy systems, and repeated high-intensity performance.

Episode Timestamps:

• 2:25 Can beginners benefit from HIIT?
• 4:20 Interval training basics and scaling effort
• 7:13 Defining vigorous effort with RPE, heart rate, and the talk test
• 11:32 Designing HIIT workouts around time and preference
• 13:48 VO2 max intervals versus shorter sprints
• 16:39 Moderate versus vigorous exercise: guidelines and time efficiency
• 18:36 Is Zone 2 and the 80/20 rule right for everyone?
• 22:50 Why Zone 2 definitions and wearables cause confusion
• 29:12 Do you need an aerobic base before starting intervals?
• 33:00 Why elite athlete training is not a blueprint for everyone
• 35:22 What low-intensity volume may do for endurance athletes
• 38:46 Double-threshold sessions, training stress, and recovery
• 41:17 Carbohydrate intake and gut training in endurance sports
• 44:31 Emerging recovery strategies and exogenous ketones
• 49:12 Lactate supplementation: promise versus current evidence
• 51:19 Fat max, metabolic flexibility, and mitochondrial capacity
• 55:31 Exercise Science podcast and evidence over hype

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Matthew Paul Clemons, MD, is a diagnostic radiologist specializing in nuclear medicine and body imaging. He is Head of Nuclear Medicine at Radiology Partners Houston and a rectal and prostate cancer specialist.

Whole-body MRI promises a detailed look under the hood—but what can a quick screening scan actually see, miss, and send you chasing? Dr. Paul Clemons explains why a whole-body MRI is a limited study, how incidental findings can lead to further tests, and why standard screening remains the better choice for most people.

Expect to learn how MRI creates images and why scan protocols take time, why open MRI systems can have important image-quality limits, how PET/MRI adds functional information, why CT and MRI can be complementary rather than redundant, how radiation and implanted devices factor into decisions, why spine findings do not always match symptoms, when conservative care deserves consideration, and where DEXA versus MRI can be useful for tracking body-composition trends.

Episodes you'll enjoy next:

• #237 — Demystifying Body Composition Testing with Dr Grant Tinsley and Dr Eric Helms: a practical companion discussion on body-composition measurement and its limits.
• #159 — Advice, Mentorships, Askholes, and Diagnostics: An Interview with Dr. Adam Sumarski: a related conversation on diagnostics and imaging in sports medicine.

Episode Timestamps:
1:50 Whole-body MRI and preventive screening
2:52 How MRI works: magnets, noise, and safety
7:05 Open MRI, magnet strength, and image quality
9:05 MRI sequences, scan time, and diagnostic protocols
11:47 Why whole-body MRI is a limited screen
12:46 Incidental findings and downstream testing
13:57 High-risk screening, rare genetic conditions, and lung limits
17:53 Sensitivity, specificity, and standard screening
24:15 PET/MRI and where whole-body imaging has a clinical role
27:05 Why MRI and PET/CT systems are expensive to install
31:59 MRI safety, implants, and pacemakers
36:36 CT versus MRI: why one scan can lead to another
38:52 Whole-body CT, radiation, and its limits
43:47 Back-pain scans: why an image may not explain symptoms
51:44 Physical therapy, surgery, and warning signs
58:46 Evaluating evidence for peptides, stem cells, and biologics
1:05:47 Choosing an orthopedic surgeon for athletic goals
1:15:24 DEXA versus MRI for body-composition trends

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Dean Guedo is an Edmonton, Alberta-based online nutrition coach and strength/nutrition professional with roughly a decade in fitness, athletics and strength sports, and Jeb Stuart Johnston is a National Board Certified Health & Wellness Coach and the Charleston, SC-based founder of Food on the Mind, specializing in emotional eating and food obsession.

Dean and Jeb join Dr. Mike T Nelson for their yearly AI check-in, getting into whether creators should disclose AI use and why deepfaked video is a very different beast than AI-assisted writing. The conversation ranges into dead internet theory, why so much hard-won fitness expertise never made it onto the internet at all, and why demanding physical skills may become more valuable, not less, as AI accelerates.

Expect to learn whether creators should disclose their AI use and why deepfaked video is a fundamentally different risk category than AI-assisted writing, why LLM writing may have already "peaked" and regresses toward the average, why fitness's hard-won oral tradition (Charlie Francis, Louie Simmons, old forums) never made it onto the internet at all, why oral defense of your own thinking may be the most AI-proof skill you can build, and why demanding physical skills could become more valuable — not less — as AI accelerates, and much more.

Connect with Dean:

• Instagram: @walk.more.king
• Website: getfluxed.ca

Connect with Jeb:

• Website: foodonthemind.com
• Instagram: @jebstuartjohnston
• Newsletter: Tangential, Inconsequential, Existential and Experiential (Substack)

Episodes you'll enjoy next:

• Episode 136 — Flex Diet, Phys Flex, Metabolism and Nutrition Research for Compound Performance (Jeb and Dean interview Dr. Mike T Nelson): Listen here
• S2 Ep 28 — High Flux Model and More for Fat Loss and Client Coaching, an interview with Dean Guedo and Jeb Johnston of StrongerU: Listen here

Episode Timestamps:

• 01:35 Welcome to the podcast & guest introductions
• 03:15 Should you disclose your AI use?
• 06:32 Deepfake video vs. AI-assisted writing: a different risk category
• 07:53 AI's exponential growth and the "singularity" question
• 11:11 What is "AI slop," and does it actually matter?
• 12:42 Why LLMs regress toward average (and the Reddit problem)
• 15:15 Falsely accused of "AI slop" for your own writing style
• 21:36 "Automate your business with AI" — the wrong things to automate
• 25:23 Dead internet theory: has AI writing already peaked?
• 26:34 Why AI can't reason about truly novel, hypothetical situations
• 28:37 Hemingway's unfinished-thought trick and "open-loop" thinking with AI
• 35:06 Why weird, opinionated writing might be AI-proof
• 44:49 Fitness's lost oral tradition: Charlie Francis, Louie Simmons, old forums
• 47:03 Stoner, the trivium, and teaching without teaching
• 48:06 Oral defense as the AI-proof assessment
• 56:08 Research vs. coaching: the application gap (Norwegian 4x4, tabata)
• 1:07:26 Will AI push us back toward hard physical skills?
• 1:15:00 Where to find Jeb & Dean

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Don Saladino is a New York-based coach and health entrepreneur who has trained A-list clients like Ryan Reynolds, Hugh Jackman, and Blake Lively since founding Drive495 in 2005.

Don Saladino has spent nearly three decades training A-list stars like Ryan Reynolds and Hugh Jackman — and in this episode, he shares the single business lesson he wishes he’d learned sooner. He and Dr. Mike also dig into why Don closed his $2M-overhead NYC gym, how tracking respiratory rate reshaped his approach to Zone 2 training, and the sobering personal loss that changed how he views performance enhancers.

Expect to learn why Don stopped over-certifying and started looking at what’s leaking in his business, how he built 17 years of trust with a client like Ryan Reynolds, the real financial toll of running a NYC gym (think $1M rent and $2M overhead), what tracking respiratory rate taught him about Zone 2 training volume, his honest take on performance enhancers at 49 (natural), and the personal loss that reshaped how he views unsupervised PED use, and much more.

Connect with Don:

• Website
• Instagram
• YouTube

Episodes you'll enjoy next:

• #402 — VO2 Max, Zone 2 Training & the Psychology of Human Performance — Ben Skutnik: Listen here
• #397 — How Elite Bodybuilders Think About Problem-Solving, Business and Nutrition with Coach Cliff Wilson: Listen here

Episode Timestamps:

• 2:26 — #1 Business Lesson: Stop Over-Certifying, Start Looking at What’s Leaking
• 5:43 — “Content Is King, Distribution Is the Kingdom”
• 8:35 — Take Risks Early: Betting on Yourself Before Responsibilities Pile Up
• 10:58 — Learning Business Over Breakfast: The NYC Advantage
• 12:01 — The Art of Adding Value Without an Agenda
• 13:32 — Working With Ryan Reynolds for 17 Years: Trust, Humility & Knowing You’re Replaceable
• 21:12 — What It Really Takes to Work With High-Profile Clients
• 26:26 — Actors vs. Athletes: Which Is Harder to Train?
• 28:39 — Performance Enhancers: Don’s Honest Take at 49, Natural
• 36:31 — Tracking Respiratory Rate & Rethinking Zone 2 Volume
• 38:37 — Closing the NYC Gym & Pivoting to Digital
• 43:35 — The Real Cost of Running a NYC Gym: $1M Rent, $2M Overhead
• 44:32 — Business Lessons You Can’t Learn at Harvard
• 46:09 — The “Integrated Wellness” Facility Trend: Is Anyone Actually Getting It Right?
• 1:05:26 — The Rise of Recovery Studios: New Happy Hour or Legit Wellness?
• 1:08:44 — A Personal Loss & a Stark Warning on Unsupervised PED Use
• 1:16:27 — Where to Find Don Saladino

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Dr. Ben Skutnik, PhD, CSCS*D, NSCA-CPT*D, is an Assistant Professor of Kinesiology and Human Performance Lab Director at Butler University and Head of Nutrition Coaching at Power Athlete.

Dr. Ben Skutnik joins the show to separate fact from fad in aerobic training, debunking zone 2 hype and explaining why VO2 max matters but isn't everything.

Expect to learn why reading scientific literature is its own skill, how uncontrolled variables quietly derail hypertrophy and menstrual-cycle training research, why treating people as fragile backfires, why anecdote in human performance often outruns the research, how "closing the loop" with clients beats chasing mechanisms, what the Norwegian 4x4 method gets right (and what most zone 2 research gets wrong about training zones), and how to actually build VO2 max with the critical power model, and much more.

Connect with Ben:

Episodes you'll enjoy next:

Episode Timestamps:

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