Dr Brennan Spiegel (physician, gastroenterologist, and author of Pull) and Dr Lachlan Kent (cognitive scientist and founder of Mental Gravity) drop an emergency episode to unpack one of the most extreme acts of gravity defiance ever witnessed: Alex Honnold climbing a 100-plus-storey skyscraper without ropes.

Using Honnold as an “extreme phenotype,” they explore what his remarkable calm reveals about fear, anxiety, graviception, and mental gravity. Drawing on neuroscience, psychology, and lived experience, they examine how Honnold’s quiet amygdala, finely tuned salience network, and relentless present-momentfocus allow him to operate where most humans would be paralysed by fear.

The episode bridges elite performance and everyday mental health, asking: what can the rest of us learn—safely—from someone who literally does not fear falling?

1. Why Alex Honnold Matters

A real-world example of ultimate gravity resilienceFree-solo climbing as the most literal test of mental gravityAnxiety, fear of falling, and bodily panic stripped awayA window into the far edge of human psychological capacity

Fear, Falling, and the Brain

Amygdala
Honnold’s amygdala shows minimal activation to fear-inducing stimuli
Contrast with anxiety, chronic pain, IBS, and fibromyalgia, where the amygdala is hyper-vigilant

Salience Network & Anterior Insula
Detects what matters in the body and environment
Simulates graviceptive cues without triggering panic
Anchors awareness in the present moment

Being in the Moment—Taken Seriously

Honnold’s survival depends on microsecond-level presence
No anticipatory anxiety, no future projection
Finger placement, balance, and movement solved in real time
Presence as an adaptive skill—not a slogan

Gravity Sensitivity as a Continuum

Humans vary widely in tolerance for heights, G-forces, and risk
Too much fear → paralysis
Too little fear → danger
Healthy functioning lies in the middle of the curve

Mental Gravity, Anxiety, and Depression

Anxiety = anticipation of falling
Depression = being stuck or weighed down in the present
Honnold represents the opposite extreme: calm within gravity
Insights help reframe everyday anxiety as mis-tuned gravity perception

Training vs Talent

Honnold combines rare inborn traits with years of intense training
Physical: extreme strength, precision, endurance
Mental: emotional regulation, present-moment focus
Fear is not absent—it is managed and contained

What Can We Learn (Safely)?

Not to climb skyscrapers—but to train mental fitness:

• Cognitive Behavioural Therapy as mentaltraining
• Meditation as present-moment conditioning
• Breathwork, yoga, and grounding practices
• Social connection and rest as recovery
• Balancing effort and recovery (noovertraining)

Mental fitness = something you work on, not something you either have or don’t have.

One Percent Rule

You don’t need to be Alex Honnold
Channeling 1% of his presence, calm, and training can meaningfully improve everyday resilience

Timecodes

00:00 — Emergency episode & skyscraper climb
01:10 — Free Solo and gravity defiance
02:15 — Watching the footage & bodily reactions
02:45 — Fear, falling & butterflies
03:30 — Amygdala findings
04:20 — Anxiety, pain & hyper-vigilance
05:10 — Salience network & graviception
06:20 — Courage vs fearlessness
06:50 — Gravity sensitivity across populations
07:50 — Mental gravity & anxiety
08:50 — Training, not recklessness
10:00 — Being truly in the moment
11:10 — Depression, anxiety & time orientation
12:05 — Learning from extreme phenotypes
13:20 — Mental health in a steeper world
14:20 — Training for modern life
15:20 — Mental fitness beyond CBT
16:10 — Meditation, breath & balance
17:35 — One percent of Honnold
18:30 — Closing reflections

Resources

The Gravity Doctors: https://thegravitydoctors.com
Dr Brennan Spiegel: https://brennanspiegelmd.com
Dr Lachlan Kent: https://lachlankent.au
Book — Pull: How Gravity Shapes Your Body, Steadies the Mind, and Guides Our Health

How do elite athletes use body, mind, joy, and meaning to push beyond physical limits?

Dr Brennan Spiegel (physician, gastroenterologist, and author of Pull) and Dr Lachlan Kent (cognitive scientist and founder of Mental Gravity) explore theOlympics as humanity’s greatest laboratory for defying gravity.

With the Winter Olympics approaching, they examine elite athletes as “physics-fighting engines”—bodies and minds trained to resist, redirect, and sometimes seemingly escape gravity. Through stories of Cathy Freeman, Quincy Hall, Alex Honnold, and modern superstars like Steph Curry and Luka Dončić, they show how peak performance is not just physical—it is mental gravity management.

They introduce Olympic training as a real-world expression of biogravitational medicine, where strength, balance, imagery, joy, poise, team culture, and meaning all shape how far humans can push their relationship with gravity.

1. Why the Olympics Matter to Mental Gravity

The Olympics showcase humanity at the edge of physical limits

Elite sport = everyday gravity management taken to extremes
Athletes model what it means to fight gravity physically and mentally
Peak performance = synchronization of body, brain, and meaning

Athletes as Anti-Gravity Prototypes

Cathy Freeman (Sydney 2000)
“Floating” to gold in the 400m
Home crowd as acceleration, not pressure
Up, light, fast = opposite of depression

Quincy Hall (Paris 400m Final)
Turning failure into flight
Last-minute mental reversal → physical transcendence

Basketball, Ski Jumping, SkatingLeaping, flying, spinning, managing G-forcesAngular momentum and rotational control as gravity mastery

Mental Gravity in Elite Performance

Performance depends on mental poise, not just muscle
Stillness before action
Pressure as fuel, not burden
Crowds as acceleration, not oppression
Joy as a performance amplifier

Examples:
Steph Curry — joy + precision
Luka Dončić — playfulness under pressure
Ash Barty — recovery from “the yips” through joy

Imagery, Rehearsal, and Gravity

Mental imagery as bodily rehearsal
Kyrie Irving visualizing free throws
Alex Honnold mentally climbing El Capitan before climbing it

Mental gravity = using body as template for thought and emotion

Up = energized
Down = heavy
Calm = balanced

Fear, Falling, and Mastery

Fear of falling = gravitational anxiety
Elite athletes train to feel secure within gravity
Butterflies in the belly = falling sensations
Great athletes use fear to prime—not paralyze—the nervous system

Timecodes

00:00 — Welcome & why the Olympics matter
01:00 — Peak athleticism as defying gravity
02:00 — Cathy Freeman & floating to gold
03:30 — Winter sports & G-forces
04:30 — Quincy Hall’s last-minute flight
06:00 — Mental vs physical performance
07:30 — Stillness, pressure & acceleration
09:00 — Joy as a performance tool
10:30 — The yips, anxiety & recovery
12:00 — Mental imagery in sport
13:30 — Kyrie Irving & visualization
14:45 — Alex Honnold & fear mastery
16:15 — Fear, falling & butterflies
17:45 — Biogravitational training stacks
19:00 — Team culture & social gravity
20:30 — VR, the Proteus Effect & training
22:00 — Dead hangs & gravity endurance
24:00 — Olympics as humanity’s gravity experiment
25:00 — Closing reflections

Resources

The Gravity Doctors: https://thegravitydoctors.com
Dr Brennan Spiegel: https://brennanspiegelmd.com
Dr Lachlan Kent: https://lachlankent.au
Book — Pull: How Gravity Shapes Your Body, Steadies the Mind, and Guides Our Health

Dr Brennan Spiegel (physician, gastroenterologist, and author of Pull) and Dr Lachlan Kent (cognitive scientist and founder of Mental Gravity) explore serotonin as a gravity-management molecule, reframing it not simply as a “happiness chemical,” but as a fundamental biological system that allows life to stand up, move fluids, regulate balance, and remain psychologically buoyant in a gravitational field.

Together, Brennan and Lachlan unpack new research on serotonin’s role across the gut, cardiovascular system, lymphatics, vestibular system, reproduction, and mood—showing how 95% of serotonin is produced in the gut, in symbiosis with the microbiome. They trace serotonin’s evolutionary origins from ocean life to land, altitude, and even space, and discuss practical implications for diet, exercise, sunlight, microbiome care, and mental health.

1. What Is Serotonin?

A whole-body gravity resilience molecule, not just a brainneurotransmitter

Exists in two largely separate compartments: brain and gut
Central to movement, circulation, balance, mood, and vitality
Evolutionarily conserved across plants, animals, and humans

Serotonin as a Gravity-Management System

Gut & DigestionMotility against gravity in any body orientation

Pumps & Tubes
Blood pressure regulation, cardiac contractility, lymphatic return

Balance& OrientationVestibular function; dizziness during SSRI withdrawal

Reproduction
Retrograde uterine contractions that move sperm upward against gravity

Mood &Energy
Mental elevation, vitality, resilience, and time perception

The Microbiome–Serotonin Alliance

Trillionsof microbes are required to trigger serotonin production
The gut as a “dark, sulfurous, hydrothermal” evolutionary niche
A symbiotic bargain: microbes get mobility; humans get serotonin
Changes in altitude, microgravity, and spaceflight rapidly alter serotoninbiology

STACK TEN: The Anti-Gravity Diet (introduced)

A practical framework from Pull for supporting serotonin production via tryptophan-rich foods.

Core principles:Tryptophan as substrateMicrobiome diversityDietary balance rather than supplementation alone

Therapeutic & Self-Care Implications

Dietary modification (tryptophan-rich foods, microbiome-supportive diets)Exercise and movementSunlight and time outdoorsWorking with dietitians for GI and mood conditions (e.g., low-FODMAP when indicated)Understanding limits and side effects of SSRIsNaturally supporting serotonin across body and mind

Metaphor & Meaning

The gutmicrobiome as the “spice factory” of human biologySerotonin as the true “spice of life”—powerful, regulating, and double-edgedGravity as the organizing principle linking biology, psychology, and medicine

Timecodes

00:00 —Welcome & why serotonin matters
01:10 — Serotonin beyond the “happiness chemical”
02:20 — Gut vs brain serotonin compartments
03:20 — Pumps, tubes & whole-body effects
04:25 — Lymphatics, reproduction & balance
06:20 — Evolutionary origins & gravitation
08:10 — Microbiome symbiosis metaphor
10:15 — Altitude, spaceflight & serotonin disruption
11:30 — STACK TEN diet introduced
12:45 — Diet, microbiome & mood disorders
13:50 — Dune, spice & serotonin metaphor
15:45 — SSRIs: benefits, limits & side effects
17:00 — Natural serotonin support & integration
17:45 — Closing reflections & next steps

Resources

The Gravity Doctors website: https://thegravitydoctors.com
Dr Brennan Spiegel: https://brennanspiegelmd.com
Dr Lachlan Kent: https://lachlankent.au
Book — Pull: How Gravity Shapes Your Body, Steadies the Mind, and Guides Our Health

Dr Brennan Spiegel (physician, gastroenterologist, and author of Pull) and Dr Lachlan Kent (cognitive scientist and founder of Mental Gravity) explore how diet, microbiome diversity, and serotonin production shape your capacity to stand up to gravity—physically and mentally.

They introduce the Anti-Gravity Diet and Brennan’s STACK TEN framework, a simple, evidence-informed way to support the gut’s serotonin “factories” and improve whole-body gravity resilience. Along the way, they unpack how food, fibre, omega-3s, polyphenols, vagus-nerve activation, and mindful rest all participate in the body–mind system that keeps us upright and energised.

Together, Brennan and Lachlan discuss babies as “gravity novices,” leaky gut, the gut–brain axis, evolutionary embodiment, time dilation in depression, and why serotonin—serum tone—is essential for managing the constant downward pull of Earth’s gravity.

• A holistic framework for supporting natural serotonin production—the body’s anti-gravity molecule.
  Grounded in gastrointestinal physiology, microbiome science, and biogravitational medicine.
• Not a restrictive diet — a practical, everyday toolkit for gravity resilience.

A memory device for foods that supply the raw material (tryptophan) for serotonin production:

Salmon
Turkey
Avocado
Chickpeas
Kidney beans
Tofu/Tempeh
Eggs
Nuts

Paired with:

• Fibre → feeds microbes that create short-chain fatty acids

• Omega-3s → shift the microbiome toward serotonin-supporting species

• Polyphenols → found in berries, cocoa, turmeric, and green tea

00:00 — Welcome & overview of the Anti-Gravity Diet
01:20 — Serotonin as the body’s anti-gravity molecule
04:20 — Microbiome diversity & the gut barrier
06:30 — Babies, serotonin & early gravity resilience
09:40 — Tryptophan, fibre & short-chain fatty acids
11:00 — Leaky gut, inflammation & decoherence
13:00 — Food–mood science & depression
16:40 — What to eat: introducing STACK TEN
17:00 — The ten tryptophan-rich foods
18:50 — Polyphenols, omega-3s & microbiome tuning
19:50 — Beyond diet: exercise, nature, sunlight
21:20 — Balancing sympathetic vs parasympathetic tone
23:00 — Vagus-nerve stimulation & rest-and-digest
24:30 — Gravity as the integrator across biological levels
26:00 — Life as a system for managing gravity
27:20 — Closing reflections & future topics

The Gravity Doctors website: ⁠https://thegravitydoctors.com⁠
Gravitype Quiz: virtualmedicine.org/pull
Dr Brennan Spiegel: brennanspiegelmd.com
Dr Lachlan Kent: lachlankent.au
Book — Pull: How Gravity Shapes Your Body, Steadies the Mind, and Guides Our Health

Dr. Brennan Spiegel (Cedars-Sinai) and Dr. Lachlan Kent explore how gravity shapes not only our bodies but our minds. Through the lens of Cathy Freeman’s gold-medal run, they discuss mental gravity — the feeling of emotional “weight” and lightness that defines human experience.

From Einstein’s relativity to embodied cognition and Cedars-Sinai’s virtual-reality therapy, they connect physics, psychology, and physiology to show how alignment with gravity may be the key to wellbeing. Topics include depression as a “mental gravity well,” glucose and perception, VR and levity, and how mindfulness, diet, and physical balance can help us stay buoyant in heavy times.

Key themes:

Mental Gravity: The experience of emotional and cognitive “weight,” shaped by our alignment with the physical world’s gravitational pull.

Embodied Cognition: How bodily states and forces (like gravity, glucose, or posture) shape perception and thought.Gravity Intolerance: A unifying framework for disorders where physical and mental balance are disrupted.

Mind over Matter: Using imagery, mindfulness, and movement to generate upward momentum and emotional lightness.Timecodes:

00:00 – 01:30 | Welcome to The Gravity DoctorsIntroducing Brennan and Lachlan; overview of physical and mental gravity.

01:30 – 03:50 | The Cathy Freeman StoryHow Cathy transcended the “weight of expectation” to run with joy and lightness — an example of mental gravity at its best.

03:50 – 06:00 | The Weight of EmotionExploring why positive emotions feel light and negative emotions feel heavy — from embodied metaphors to physical postures of depression.

06:00 – 08:10 | Embodied Cognition and Glucose StudiesBrennan cites research showing blood-glucose levels alter perception of hill steepness — a literal bridge between physiology and perception.

08:10 – 11:00 | The Birth of the Theory of Mental GravityLachlan recalls his “aha” moment linking Einstein’s general relativity lecture on black holes to psychological depression — both described using the same language of heaviness, collapse, and isolation.

11:00 – 12:40 | Gravity Wells, Black Holes, and RecoveryComparing mental “gravity wells” to depression — but unlike black holes, people can pull themselves out.

12:40 – 16:20 | Champagne, Joy, and the Physics of EmotionWhy celebration rituals mirror gravitational metaphors — bubbles rising, buoyancy, and the inevitable “come-down.”

16:20 – 19:30 | Virtual Reality as a Gravity-Hacking ToolCedars-Sinai research: VR experiences that simulate floating or flying reduce pain, anxiety, and inflammation — measurable physiological effects of simulated levity.

19:30 – 22:00 | Mindfulness and Mental ImageryUsing mental imagery and meditation to reshape the brain-body landscape and foster feelings of lightness and alignment.

22:00 – 25:50 | The Continuum of Mind and BodyWhy mind and body aren’t separate but part of one continuous system — like a cross-country landscape shifting seamlessly from desert to sea.

25:50 – 28:30 | Gravity Intolerance and Health ResilienceReframing conditions like IBS, POTS, and anxiety as variations of gravity intolerance; maintaining physical and mental balance as the essence of wellbeing.

28:30 – 30:00 | Everyday Applications & Closing ReflectionsFrom mindfulness to serotonin-rich diets and time in nature — practical tools to stay buoyant.

Final reflections on finding balance between empowerment and medical treatment.

Want to discover your 'Gravitype'? Visit The Gravity Doctors website:https://thegravitydoctors.com/

Order Brennan's book "Pull" to learn more about how gravity shapes your health in both body and mind via his personal ⁠⁠personal website⁠⁠: https://www.brennanspiegelmd.com/pull

Visit ⁠⁠Lachlan's website ⁠⁠to learn more about his work in mental gravity: https://lachlankent.au/

Music by ⁠ALLIRA⁠ and Visceral Sound - https://www.youtube.com/@ALLIRAmusic

Recording at ⁠JTB Studio⁠ by David Iskandaryan.

In this uplifting and deeply human episode of The Gravity Doctors, Dr. Brennan Spiegel (Cedars-Sinai gastroenterologist and author of PULL) and Dr. Lachlan Kent (cognitive scientist and theorist of Mental Gravity) sit down with Harmon Clarke, a patient-turned-researcher whose remarkable recovery story illuminates the future of biogravitational medicine.

From septic shock and 200 days in hospital to yoga teacher, breathwork practitioner, and health researcher, Harmon’s journey embodies resilience, creativity, and the healing power of re-engaging with gravity. Together, they explore how movement, inversions, virtual reality, and breathwork can transform pain and depression into buoyancy and balance — culminating in a spontaneous “Gravity Rap” that captures the spirit of the show.

Core Themes

• Gravity as a unifying metaphor for physical and mental health

• Movement and inversion therapy for resilience and recovery

• Virtual reality and embodied cognition

• Tensegrity, balance, and the biomechanics of wellbeing

• Patient empowerment and the hero’s journey in healing

• Biogravitational medicine as a synthesis of East–West paradigms

  
  

00:00 – Welcome and Introductions

01:00 – Facing the Grave

03:00 – Virtual Reality and the Mind–Body Connection

06:00 – Yoga, Breathwork, and Natural Recovery

08:00 – The Science of Inversion and Tensegrity

14:00 – Hospitals and Gravity Intolerance

18:00 – Depression as a Gravitational Condition

24:00 – Cathy Freeman and Gravitational Flow

25:45 – East Meets West

30:00 – Rebalancing Medicine

33:00 – The Simple Tools of Healing

35:00 – Designing the Future of Biogravitational Medicine

38:00 – Generational Health and Modern Comfort

41:00 – The Gravity Rap Finale

Order Brennan's book "Pull" to learn more about how gravity shapes your health in both body and mind via his personal ⁠⁠personal website⁠⁠.

Visit ⁠⁠Lachlan's website ⁠⁠to learn more about his work in mental gravity.

Music by ⁠ALLIRA⁠ and Visceral Sound

Recording at JTB Studio by David Iskandaryan.

Editing by Dr Karisma Suchak.

Biogravitational Medicine is a holistic approach to maintaining health in both body and mind. It's like a toolkit where you can find what works for you and your particular situation. Here are our top ten that work for most people most of the time. (As always, consult a doctor for personalised medical advice before attempting anything that might pose a risk to your physical or mental health, or for treatment of acute or chronic conditions. The information here is for educational and information purposes only.)

Order Brennan's book "Pull" to learn more about how gravity shapes your health in both body and mind via his personal ⁠personal website⁠.

Visit ⁠Lachlan's website ⁠to learn more about his work in mental gravity.

Music by ALLIRA and Visceral Sound

This episode was recorded at ⁠Myst Music⁠.

Audio engineering by Jeremy Roberts.

Audio and video editing by Dr Karisma Suchak.