Nashville BiohackingWith Scott Crosbie
Practitioner consultation at Next Health Nashville

Glossary

The language of proactive longevity.

A plain-English glossary of the terms you'll see throughout the journal, the approach, and Scott's book. Pulled from clinical practice and from OPTIMIZED.

Therapies

Hyperbaric Oxygen Therapy

also: HBOT

Therapies

HBOT is breathing pure oxygen inside a pressurized chamber, allowing blood plasma to absorb 10–15× more oxygen than at normal atmospheric pressure. Research uses include traumatic brain injury, post-surgical healing, stem cell mobilization, and (in select protocols) telomere lengthening.

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Whole-Body Cryotherapy

also: WBC

Therapies

Whole-body cryotherapy is a 2–3 minute exposure to ultra-cold air (-200°F to -250°F) inside a chamber, triggering vasoconstriction, anti-inflammatory cytokine release, and a rebound surge of oxygenated blood. Commonly used for athletic recovery, inflammation, mood, and metabolic activation.

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EBOO

also: Extracorporeal Blood Oxygenation and Ozonation

Therapies

EBOO is an advanced therapy in which a portion of blood is drawn, filtered, treated with medical-grade ozone, and returned. It's used for chronic inflammation, autoimmune patterns, and post-viral recovery. Always performed under licensed clinical supervision.

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Red Light Therapy

also: Photobiomodulation, RLT, Low-Level Laser Therapy

Therapies

Red light therapy uses specific wavelengths of red and near-infrared light (typically 630–850 nm) to stimulate cellular activity — particularly mitochondrial energy production. Used for skin health, recovery, mood support, and cellular optimization. Non-invasive and well-tolerated.

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Infrared Sauna

Therapies

An infrared sauna uses invisible infrared light to heat the body directly — rather than the air around it — producing a deep, profuse sweat at lower ambient temperatures than a traditional sauna. Research shows regular sauna use is associated with cardiovascular benefit and reduced all-cause mortality.

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PRP

also: Platelet-Rich Plasma

Therapies

PRP is plasma concentrated with platelets from the patient's own blood, then re-injected to deliver growth factors to a target tissue. Common applications include hair restoration, joint regeneration, soft-tissue healing, and aesthetic skin treatments.

Cellular Biology

Senescent Cells

also: Zombie Cells

Cellular Biology

Senescent cells are older, damaged cells that have stopped dividing but resist being cleared from the body. They linger in tissue, contribute to chronic inflammation, and crowd out healthier cells. Clearing them — a process called senolysis — is one of the most actively researched targets in modern longevity medicine.

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NAD+

also: Nicotinamide Adenine Dinucleotide

Cellular Biology

NAD+ is a coenzyme present in every cell that's central to energy production (ATP synthesis), DNA repair, and the function of sirtuins — enzymes involved in longevity signaling. NAD+ levels fall roughly 50% between ages 40 and 60. Replenishing it through IV therapy, injections, or precursors is a foundational longevity intervention.

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Mitochondria

Cellular Biology

Mitochondria are the energy factories inside every cell — converting nutrients into ATP, the body's energy currency. Mitochondrial efficiency declines with age, which is why supporting them (through NAD+, peptides, red light therapy, and metabolic optimization) is foundational to feeling energetic at any age.

Telomeres

Cellular Biology

Telomeres are protective caps at the ends of chromosomes that shorten each time a cell divides. When they become too short, cells stop dividing or die. Telomere length is one of the most studied biomarkers of biological aging, and certain interventions (hyperbaric oxygen therapy, lifestyle factors) have been associated with telomere lengthening.

Autophagy

Cellular Biology

Autophagy is the body's cellular cleanup process — recycling damaged proteins and organelles. It's triggered by fasting, exercise, and certain compounds. Robust autophagy is associated with reduced age-related disease risk and improved cellular function.

Chronic Inflammation

also: Inflammaging

Cellular Biology

Chronic inflammation is the persistent, low-grade immune activation that underlies most age-related disease. Distinct from acute (helpful) inflammation, it's measurable through markers like hs-CRP and is a major target for anti-aging interventions — diet, sleep, recovery therapies, and certain peptides all reduce it.

Stem Cells

Cellular Biology

Stem cells are undifferentiated cells with the ability to develop into specialized cell types and repair tissue. Mobilizing the body's own stem cells (one of the documented effects of hyperbaric oxygen therapy) and clinical use of exosomes and PRP are active areas of regenerative medicine.

Glutathione

Cellular Biology

Glutathione is the body's master antioxidant — a tripeptide that protects cells from oxidative damage and supports phase-II liver detoxification. Levels decline with age and stress; replenishing through IV therapy, IM injections, or precursors (NAC) is a common longevity protocol.

Exosomes

Cellular Biology

Exosomes are tiny vesicles released by cells that carry signaling molecules — RNA, proteins, lipids. In regenerative medicine, mesenchymal stem cell-derived exosomes are used to deliver healing signals to tissue without the cells themselves. Used in aesthetics and orthopedics.

Longevity Science

Biological Age

also: Bio Age, Phenotypic Age, Epigenetic Age

Longevity Science

Biological age is a measurement of how your body is functioning compared to chronological age. Calculated from biomarkers (DNA methylation patterns, telomere length, blood chemistry), it can indicate whether someone is aging faster or slower than the calendar suggests. Two 45-year-olds can have biological ages a decade apart.

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Hormesis

Longevity Science

Hormesis is the biological principle that small, controlled stressors — cold exposure, heat exposure, exercise, fasting, hypoxia — strengthen the body's adaptive systems. The opposite of comfort-as-safety; controlled stress is one of the foundations of longevity.

Peptides

BPC-157

also: Body Protective Compound 157

Peptides

BPC-157 is a synthetic peptide derived from a protein in gastric juice, used clinically for soft-tissue injury, gut healing, and inflammation reduction. It's one of the most-researched peptides in regenerative medicine. Like any therapeutic peptide, it should be sourced from a compounding pharmacy and dosed by a clinician — not bought online.

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FOX04

also: FOX04-DRI

Peptides

FOX04 is a mitochondrial peptide designed to selectively kill senescent cells — the dysfunctional 'zombie cells' that drive aging and inflammation. Typical clinical protocols run 5 injections over 10 days. Senolytic therapy is one of the most actively researched longevity frontiers.

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Peptide Therapy

Peptides

Peptide therapy is the clinician-prescribed use of short amino-acid chains that signal specific biological responses — injury healing, muscle growth, gut repair, immune modulation, senescent cell clearance. Always sourced from compounding pharmacies and prescribed by qualified clinicians.

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Hormones

BHRT

also: Bioidentical Hormone Replacement Therapy

Hormones

BHRT uses hormones molecularly identical to the body's own — testosterone, estrogen, progesterone, DHEA — to restore levels that have declined with age. Optimization protocols (vs. traditional replacement) target youthful, vibrant ranges and adjust based on frequent re-testing.

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TRT

also: Testosterone Replacement Therapy

Hormones

TRT is the clinical replacement of testosterone in adult men with documented decline — restoring levels associated with energy, mood, body composition, libido, and recovery. Modern protocols often combine testosterone with adjuncts (HCG, AI medications, DHEA) and are guided by biomarker bloodwork rather than symptoms alone.

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Biomarkers

Grip Strength

Biomarkers

Grip strength is one of the most reliable proxies for biological age and all-cause mortality. Research shows scores above 50 kg in adults correlate with the strength profile of a healthy 20-year-old. Building and maintaining grip strength is one of the simplest, highest-leverage longevity interventions.

HbA1c

also: Hemoglobin A1c, Glycated Hemoglobin

Biomarkers

HbA1c is a blood marker reflecting average blood sugar over the previous 2–3 months. It's the primary marker for diabetes screening and metabolic health. Optimal ranges for longevity (often below 5.4) are tighter than the clinical 'not diabetic' threshold (below 5.7).

ApoB

also: Apolipoprotein B

Biomarkers

ApoB is a protein found on every potentially atherogenic lipoprotein particle (LDL, VLDL, etc.). Measuring ApoB directly tells you how many of these particles are in circulation — a far more reliable cardiovascular risk marker than LDL cholesterol alone.

Diagnostics

Biomarker Panel

also: Functional Bloodwork, Comprehensive Lab Panel

Diagnostics

A biomarker panel is comprehensive lab work measuring 40–80+ markers across metabolic, hormonal, inflammatory, nutritional, and cardiovascular systems. Unlike a standard physical (which screens for disease), a functional panel uses optimal ranges — the levels at which people feel and function their best.

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InBody Scan

Diagnostics

An InBody scan is a 60-second bioimpedance body composition test that measures fat mass, muscle mass, body water, visceral fat, and segmental balance. Far more informative than a standard scale, it's used to track training, nutrition, and optimization progress with hard numbers.

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VISIA Facial Analysis

Diagnostics

VISIA is a clinical imaging system that quantifies aspects of skin you can't easily see — UV damage, deep pigmentation, porphyrins (bacterial activity), vascular patterns, wrinkles, and texture. It produces a numeric baseline that tracks how aesthetic and longevity interventions are actually changing skin health.

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Metabolism

GLP-1

also: Glucagon-Like Peptide-1, Semaglutide, Tirzepatide, Ozempic, Mounjaro

Metabolism

GLP-1 (Glucagon-Like Peptide-1) is a naturally-occurring hormone that regulates appetite, insulin response, and gastric emptying. Synthetic GLP-1 agonists like semaglutide and tirzepatide are now widely used for metabolic optimization and weight regulation — and have shown cardiovascular and renal benefits beyond weight effects.

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Recovery

Vagus Nerve

Recovery

The vagus nerve is the longest nerve in the autonomic nervous system, connecting the brain to most major organs. It controls the parasympathetic (rest and repair) response. Vagal tone — the strength of this signal — is a key marker of nervous system regulation and recovery capacity.

Go Deeper

Every term explained in full in the book.