Rob and Stephan analyze their 2025 health data, discuss the validity of "biological age" metrics, and set systems-based goals for the coming year.

📝Summary

In this episode, biological data scientists Rob and Stephan explore how to use wearable data to review the past year and plan for a better future. They critique the "year in review" features of popular apps, debating whether these metrics provide actionable insights or merely gamified motivation. The discussion moves into the science of cardiovascular age and pulse wave velocity, highlighting how short-term exercise interventions might alter arterial stiffness markers. Reflecting on personal growth, Rob shares his transition from manual to more automated tracking for perceived happiness, while Stephan outlines a systematic "Past Year Review" framework to replace traditional New Year’s resolutions. The episode concludes with a look at 2026 technological trends, including the potential for better batteries, screenless GPS wearables, and new FDA regulatory pathways that could integrate consumer health tech into clinical practice.

⏳Chapters

00:00:00 Year in Review: Discussing App Recaps and Comparisons 

00:07:47 Feedback Loops: How to Use Data Trends for Behavioral Change 

00:24:48 Biological Age: Decoupling Marketing from Physiological Truth 

00:35:15 Cardiovascular Age: Pulse Wave Velocity and Arterial Adaptation 

00:48:57 The Importance of Controls: Lessons from a Cold Exposure Study 

01:03:17 Nerve Health: Tracking Impact and Recovery via Smart Scales 

01:06:54 Quitter’s Day vs. Systems: Why New Year’s Resolutions Fail 

01:08:15 The Past Year Review: A Data-Driven Framework for Lifestyle Design

01:12:26 2026 Goals: Marathons, Biking Rivalries, and Life Balance 

01:21:10 Professional Focus: Cutting Out Distractions to Finish Projects

01:23:54 One-Bag Travel: Reflections on Minimalist Gear and Efficiency 

01:27:03 Future Wearables: GPS, Battery Tech, and FDA Regulation

📚Resources

Oura 2025 year in review

Whoop 2025 year in review

"Comparison is the death of joy." - Mark Twain

Arthur C. Brooks Personality Types Quiz

Doctor Mike confronting Dr. Amen

“Imperfect data can still have value” - Joe Barnard (from https://bps.space/)

Heroic dose

"Long-term consistency trumps short-term intensity." - Bruce Lee

Whoop biological age

VO2max and longevity

Lancet Public Health: “7,000 steps/day linked to clinically meaningful health improvements.”: https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(25)00164-1/ 

Pulse Wave Velocity (PWV): https://en.wikipedia.org/wiki/Pulse_wave_velocity 

PWV relationship to blood pressure: https://www.pnas.org/doi/10.1073/pnas.1814392115 

Arteries: https://my.clevelandclinic.org/health/body/22896-arteries 

Muscle memory in strength training

Endurance memory exists and is driven by persistent structural adaptations (capillary density and cardiac remodeling) and epigenetic priming.

“Quitter's day” is the second Friday in January.

Stephan's Past Year Review instructions

Stephan's backpack and packing list

The Greek philosopher Plato proposed the Theory of Forms, asserting that the physical world consists of imperfect copies of eternal, perfect, and abstract "master" templates existing in a higher realm of reality.

Oura executives (CEO and CMO) on new regulatory pathway for wearables

🎙️About

Fit For Science is a deep-dive podcast hosted by two biological data scientists, Rob and Stephan, exploring the intersection of research, health tech, and data-driven lifestyle design. The hosts provide evidence-based systems, layered with practical "N=2" personal experimentation, to cut through the noise in the health and fitness industry.

Learn more

Subscribe on your favorite platforms

YouTube

Spotify

Apple Podcasts

Amazon Music

⚠️Disclaimer: This podcast represents our own opinions and is for informational purposes only. It does not constitute medical or financial advice or a professional relationship.

Data scientists Rob and Stephan discuss Apple's latest sleep algorithm improvements, the evolving landscape of wearable subscriptions, and three reasons for personal (health) tracking.

📝Summary

In this episode, the hosts examine the rapid iteration cycles of health technology, starting with Apple’s recent algorithmic improvements to sleep stage detection. They explore the "subscriptionification" of the wearable industry, comparing business models from Whoop, Oura, and Eight Sleep while debating the value of AI-driven health coaching and gamification metrics like "biological age". The discussion transitions into nutritional tracking, covering the medical origin of continuous glucose monitors (CGMs) and the practical challenges of picture-based food logging. Finally, they dive into three reasons behind self-quantification, highlighting for example how the Hawthorne effect, where the act of observation itself alters behavior, can be a powerful tool for behavior change.

⏳Chapters

00:00:00 Apple Sleep Algorithm: Improved deep sleep and awake detection 

00:09:00 Continuous Sleep: Moving beyond 30-second epoch sleep stages 

00:13:20 Data Repositories: The lack of centralized sleep data compared to genomics 

00:17:20 Subscription Models: The industry shift from ownership to service licenses 

00:35:00 AI Coaching: The utility and hype of AI advisors in wearables 

00:44:00 Eight Sleep: Thermal regulation, bed tracking, and high-tier costs 

01:13:50 CGM Deep Dive: Continuous glucose monitoring and individual responses 

01:29:30 Nutrition Tracking: From barcodes to picture-based food logging 

01:35:20 The Hawthorne Effect: Using observation as a tool for behavior change 

01:42:00 Management Philosophy: Drucker and Kelvin on the necessity of measurement

01:47:40 Technological Optimism: Staying healthy to witness the future

📚Resources

Apple sleep staging paper with updated appendix: https://www.apple.com/health/pdf/Estimating_Sleep_Stages_from_Apple_Watch_Oct_2025.pdf 

The Quantified Scientist - Can Wearables Predict How You Feel?: https://youtu.be/iwZrtb6tlUo 

Apple Health uses SDNN (Standard Deviation of Normal-to-Normal intervals) as its metric for Heart Rate Variability, while others (such as Oura, Garmin, and Fitbit) use RMSSD.

Eight Sleep: https://www.eightsleep.com/ 

Dexcom G7 & Stelo: https://www.dexcom.com/ 

FreeStyle Libre by Abbott: https://www.freestyle.abbott/ 

Levels Health App: https://framer.levels.com/ 

A glucose spike is a rapid rise in blood sugar, defined generally as above 140 mg/dL.

Nature Medicine paper on individual variations in glycemic responses: https://www.nature.com/articles/s41591-025-03719-2

Clarification: Not Ultrahuman (https://www.ultrahuman.com/) but Supersapiens (https://www.supersapiens.com/) use CGMs for optimal metabolic fueling/efficiency.

rTracker app by Robert Miller: https://apps.apple.com/us/app/rtracker-track-it-your-way/id486541371

Star Trek Qs (immortal species): https://en.wikipedia.org/wiki/Q_(Star_Trek) 

Isaac Asimov's Foundation as TV series: https://en.wikipedia.org/wiki/Foundation_(TV_series) 

Three Body Problem as TV series: https://en.wikipedia.org/wiki/3_Body_Problem_(TV_series) 

🎙️About

Fit For Science is a deep-dive podcast hosted by two biological data scientists, Rob and Stephan, exploring the intersection of research, health tech, and data-driven lifestyle design. 

Learn more: https://www.fitforscience.com/ 

Subscribe on your favorite platforms

YouTube: https://www.youtube.com/@FitForScience 

Spotify: https://open.spotify.com/show/56TjUxuMsPETb0kGEJ7nwf 

Apple Podcasts: https://podcasts.apple.com/us/podcast/fit-for-science/id1863479802

Amazon Music: https://music.amazon.de/podcasts/c3e54ee7-4a2c-442e-a59f-553fbfb02b11/fit-for-science 

⚠️Disclaimer: This podcast represents our own opinions and is for informational purposes only. It does not constitute medical or financial advice or a professional relationship.

Rob and Stephan discuss the efficacy of blood pressure wearables, morning activation protocols like light therapy, and the use of nicotine as a cognitive stimulant.

📝Summary

In this episode, biological data scientists Rob and Stephan examine the evolution of wearable technology, focusing on Garmin’s Firstbeat sleep staging and the current limitations of wrist-based blood pressure monitoring. They contrast Apple’s cautious notification-based approach to hypertension with the calibration-heavy methods of competitors, while discussing why continuous monitoring might be superior to traditional resting spot checks. The conversation shifts to personal morning "activation" rituals, featuring a deep dive into light therapy for circadian rhythm alignment and the controversy surrounding cyclic hyperventilation. Finally, they explore the potential cognitive benefits and physiological risks of nicotine supplementation, alongside Stephan’s "Minimal Effective Dosage" daily strength exercise for long-term health maintenance.

⏳Chapters

00:00:00 Wearable Evolution: Firstbeat Sleep Staging and Incremental Innovation

00:09:12 Scientific Standards: Peer Review vs. Corporate White Papers 

00:13:12 Blood Pressure: Cardiovascular Risk and Genetic Predisposition 

00:15:07 Gold Standards: Manual Cuffs vs. Wrist-Based Sensors 

00:21:18 Apple's Approach: Hypertension Notifications and Data Integrity 

00:30:00 Future Research: Continuous Monitoring vs. Resting Spot Checks 

00:37:39 Morning Activation: Overcoming Sleep Inertia with Light Therapy 

00:42:21 Morning Routines: Caffeine, Cold Showers, and Cognitive Performance 

00:50:49 Coffee and Cholesterol: The Impact of Paper Filters on Serum LDL-C

00:52:37 Beyond Wim Hof: Cyclic Hyperventilation and Acupuncture Mats 

01:00:33 Nicotine as a Nootropic: Misconceptions, Risks, and Half-Life 

01:13:39 Minimal Effective Dosage: Non-Negotiable Daily Exercise Habits 

📚Resources

2019 Firstbeat (now Garmin) sleep analysis paper: https://assets.firstbeat.com/firstbeat/uploads/2019/11/Firstbeat-Sleep-Solution_white-paper_short.pdf 

ASCVD: Atherosclerotic Cardiovascular Disease

MACE: Major Adverse Cardiovascular Events

Blood pressure (BP) & ASCVD risk: https://jamanetwork.com/journals/jamacardiology/fullarticle/2766469 

Blood pressure at night: 10%–20% decrease

Sleep inertia: https://en.wikipedia.org/wiki/Sleep_inertia

Luminette glasses: https://myluminette.com/ 

Light as major zeitgeber: https://pubmed.ncbi.nlm.nih.gov/19708721/ 

Stephan's morning: morning.polytechnist.me 

Use paper filters for coffee to reduce LDL-C: https://www.ahajournals.org/doi/10.1161/01.ATV.11.3.586 

Cyclic hyperventilation (Bhastrika Pranayama) for sympathetic activation: https://pubmed.ncbi.nlm.nih.gov/24799686/ 

Stephan's nicotine page: https://stephanreichl.notion.site/Nicotine-2d0301f67e4c80faa34ec6c032a35bd5

Stephan's “minimal effective dose” strength training: https://stephanreichl.notion.site/MED-Resistance-Training-7ecf3c212aa248838903dbfbfcb7230e

Hot Baths as exercise: https://journals.physiology.org/doi/epdf/10.1152/ajpregu.00012.2025

🎙️About

Fit For Science is a deep-dive podcast hosted by two biological data scientists, Rob and Stephan, exploring the intersection of research, health tech, and data-driven lifestyle design. The hosts provide evidence-based systems, layered with practical "N=2" personal experimentation, to cut through the noise in the health and fitness industry.

Learn more: https://www.fitforscience.com/ 

Subscribe on your favorite platforms

YouTube: https://www.youtube.com/@FitForScience 

Spotify: https://open.spotify.com/show/56TjUxuMsPETb0kGEJ7nwf 

Apple Podcasts: https://podcasts.apple.com/us/podcast/fit-for-science/id1863479802

Amazon Music: https://music.amazon.de/podcasts/c3e54ee7-4a2c-442e-a59f-553fbfb02b11/fit-for-science 

⚠️Disclaimer: This podcast represents our own opinions and is for informational purposes only. It does not constitute medical or financial advice or a professional relationship.

Rob and Stephan dive into the "deep sleep problem" of the Apple Watch, share their personal motivations for long-term self-quantification, and provide a science-heavy look at why creatine is one of the most underappreciated supplements in medicine.

📝Summary

In this episode, Rob addresses the controversy surrounding Apple Watch sleep staging based on a recent study comparing wearables to polysomnography, explaining why the device often underestimates deep sleep stages while remaining a top-tier consumer tool. The hosts explore the "why" behind their data-driven lifestyles, with Rob detailing his unique multi-year deep-phenotyping research and Stephan describing the psychological benefits of leveraging the Hawthorne effect for behavioral change. Finally, they provide a comprehensive breakdown of creatine supplementation, addressing medical misconceptions about kidney health, while also highlighting emerging research on creatine’s cognitive benefits.

⏳Chapters

00:02:00 The Sleep Study: Comparing Apple Watch to the Gold Standard

00:12:41 Staging Accuracy: Pattern Recognition and Consistency Preferences

00:17:15 Battery vs. Precision: Why Apple Limits Sensor Input

00:24:20 Evolving Models: Firstbeat, Garmin, and Machine Learning on the Edge

00:29:48 Why We Track: Rob’s Multi-Year Deep Phenotyping Research

00:38:29 Finding the Niche: From Science Communication to YouTube

00:44:17 Daily Routines: When and How to Check Your Data

00:50:52 Healthy Limits: Preventing Tracking-Induced Anxiety

00:56:48 Creatine and Kidney Health: Addressing Doctor Concerns

00:57:50 Informed Discussions: How to Present Data to Medical Professionals

01:08:18 Cellular Energy: Creatine’s Role in ATP Production

01:13:04 Brain Health: Creatine for Sleep Deprivation and Neuroprotection

01:19:32 Personal Risk Analysis: Hair Loss, Finasteride, and Trade-offs

01:28:03 Soleus Muscle Correction and Smartwatch Histories

📚Resources

Rob's sleep study preprint: https://osf.io/preprints/psyarxiv/27wun_v1 

Apple sleep staging paper: https://www.apple.com/health/pdf/Estimating_Sleep_Stages_from_Apple_Watch_Oct_2025.pdf 

Quantization in AI: https://arxiv.org/abs/2106.08295 

Oura technical support confirmed that Oura's sleep staging is processed offline by the Oura App, which runs the complete sleep staging pipeline using the physiological signals shared by the ring, regardless of internet connection.

Simon Sinek's Start with Why: https://youtu.be/u4ZoJKF_VuA 

EXG Glossary: EEG (Electroencephalogram), EOG (Electrooculogram), ECG  (Electrocardiogram), EMG (Electromyogram)

Supplement research database: https://examine.com 

Goodhart's Law: When a measure becomes a target, it ceases to be a good measure.

Kidney physiology: https://youtu.be/l128tW1H5a8 

Stephan's Creatine page: https://stephanreichl.notion.site/Creatine-117301f67e4c80fcbce8e9f489aad9c9 

Hypertrophy (size) vs hyperplasia (numbers): https://pubmed.ncbi.nlm.nih.gov/5917072/ 

Fidgeting (NEAT) study: https://pubmed.ncbi.nlm.nih.gov/11101470/ 

🎙️About

Fit For Science is a deep-dive podcast hosted by two biological data scientists, Rob and Stephan, exploring the intersection of research, health tech, and data-driven lifestyle design. The hosts provide evidence-based systems, layered with practical "N=2" personal experimentation, to cut through the noise in the health and fitness industry.

Learn more: https://www.fitforscience.com/ 

Subscribe on your favorite platforms

YouTube: https://www.youtube.com/@FitForScience 

Spotify: https://open.spotify.com/show/56TjUxuMsPETb0kGEJ7nwf 

Apple Podcasts: https://podcasts.apple.com/us/podcast/fit-for-science/id1863479802

Amazon Music: https://music.amazon.de/podcasts/c3e54ee7-4a2c-442e-a59f-553fbfb02b11/fit-for-science 

⚠️Disclaimer: This podcast represents our own opinions and is for informational purposes only. It does not constitute medical or financial advice or a professional relationship.

Biological data scientists Rob and Stephan discuss what to track and why, the psychological value of blue-light blocking glasses, and the multifaceted longevity benefits of "plogging".

📝Summary

In this episode, biological data scientists Rob and Stephan dive deep into the philosophy of self-quantification. They explore why tracking the "unobservable" state of sleep provides the highest return on investment and how the Hawthorne Effect can be used as a personal tool for behavior change. The discussion shifts to the science of blue light blocking glasses, debunking common marketing claims while acknowledging the power of psychological anchors in evening routines. Finally, the hosts introduce "Plogging", the Swedish habit of picking up litter while jogging, as a multifaceted longevity practice that combines movement, grip strength, and community purpose.

⏳Chapters

00:00:53 Wearables Philosophy: A discussion on what to track and why

00:03:44 The SNAP Framework: Sleep, Nutrition, Activity, and Purpose

00:06:18 Differentiating between Activity vs. Exercise

00:09:41 Training Intensity: HIIT for speed and Zone 2 training for endurance

00:15:30 Hardware Deep Dive: Comparing sports tracking versus sleep staging

00:18:34 GPS Math and Measurement Noise: How devices calculate distance

00:22:57 Market Leaders and Reviewer Ecosystems

00:33:25 Blue Light Blocking Glasses: Examining the shifting evidence

00:46:40 Psychological Anchors: How wearing red glasses signal to begin the evening routine

00:49:56 Cold Exposure: Debunking metabolic and fat-loss claims

00:55:38 Advanced Sleep Tech: EEG, polysomnography, and 30-second sleep staging epochs

01:11:22 Tool Time - Plogging: Stephan introduces the ultimate longevity habit

01:19:50 Systematic Culture: Comparing rule-following cultures in Austria vs the Netherlands

01:28:40 Ig Nobel Science: Maternal garlic ingestion

01:32:38 Immune System Triggers: How immune events may trigger Vitiligo

📚Resources

Plogging: https://en.wikipedia.org/wiki/Plogging

Plogging device: https://www.amazon.de/dp/B09L2M9BPC

Plogging instructions: https://stephanreichl.notion.site/2d4301f67e4c804a8be1d693086c2c14 

Optimistic Nihilism by Kurzgesagt: https://youtu.be/MBRqu0YOH14 

Exercise smart watch companies founding years and countries: Polar 1977 Finland, Garmin 1989 USA (since 2010 Swiss), and Coros 2014 China

Stephan's evening routine: http://evening.polytechnist.me 

Stephan's morning routine: http://morning.polytechnist.me 

💡Corrections

Why We Sleep by Matthew Walker (https://www.goodreads.com/book/show/34466963-why-we-sleep) was published in 2017, not 2014. Stephan started sleep tracking in 2016 with an iPhone app called Sleep cycle (https://sleepcycle.com/) and therefore thought the book must have been released before (turns out he was just ahead of his time).

🎙️About

Fit For Science is a deep-dive podcast hosted by two biological data scientists, Rob and Stephan, exploring the intersection of research, health tech, and data-driven lifestyle design. The hosts provide evidence-based systems, layered with practical "N=2" personal experimentation, to cut through the noise in the health and fitness industry.

Learn more: https://www.fitforscience.com/

Subscribe on your favorite platforms

YouTube: https://www.youtube.com/@FitForScience

Spotify: https://open.spotify.com/show/56TjUxuMsPETb0kGEJ7nwf

Apple Podcasts: https://podcasts.apple.com/us/podcast/fit-for-science/id1863479802

Amazon Music: https://music.amazon.de/podcasts/c3e54ee7-4a2c-442e-a59f-553fbfb02b11/fit-for-science

⚠️Disclaimer: This podcast represents our own opinions and is for informational purposes only. It does not constitute medical or financial advice or a professional relationship.

In this inaugural episode, biological data scientists Rob and Stephan dive into the world of self-quantification. They discuss their personal setups, the reliability of popular smart rings, and share exclusive preliminary results from recent independent validation studies on sleep and fitness tracking.

🔬 Summary

Two scientists, Rob (chemist turned bioinformatician) and Stephan (mathematician turned bioinformatician), explore the intersection of technology and health.

• The Smart Ring Showdown: A deep dive into why the Oura Ring remains the current leader in sleep tracking despite battery durability issues and subscription hurdles.

• Oura technical support clarified (after some back and forth) that Oura's sleep staging is processed locally within the Oura App and is not updated or changed when the phone is connected to the internet. The ring records physiological signals and shares this data with the Oura App, which then runs the complete sleep staging pipeline offline.

• Sleep Study Insights: Rob shares findings from a 20-person sleep lab study (PsyArXiv preprint) comparing wearables against Polysomnography (PSG). Discover why the Apple Watch struggled with deep sleep while Oura remained remarkably consistent.

• The CIRCUL ring was, in fact, the worst-performing device.

• Participants were woken up at 3:00 am, not three hours after going to bed.

• Fitness Tracking (VO2max): An overview of an ongoing study at the Sports Institute in Vienna, examining how well watches from Garmin, Polar, Apple and Samsung estimate your aerobic capacity

• Bio-Logic: A look at the "Soleus Pushup" for glucose metabolism, the medical necessity of straight teeth for longevity, and the evolutionary theories behind "rear end" hair triggered by Hank Green's hilarious short.

• Correction: The Soleus muscle is located on the back of the calf, and is considered part of the calf muscle group, despite not being on the shin.

⏳ Chapters

00:00:00 Introduction: Meet Rob and Stephan

00:01:37 Smart Rings: Form Factor, Convenience, and Battery Woes

00:04:17 Customer Support and Hardware Reliability in Wearables

00:06:22 Rob’s Current Testing Suite: Samsung Galaxy Ring vs. Oura

00:07:58 Stephan’s Routine: How a Scientist Interprets Oura Data

00:10:04 Heart Rate Variability (HRV) and Temperature Baselines

00:12:04 The Case for "N=2": Cross-Validating with Multiple Devices

00:14:50 The Evolution of Heart Rate Tracking: PPG vs. ECG

00:18:04 Comparing the App Experience: Oura, Whoop, and Samsung

00:20:46 Budget Alternatives: The Amazfit Ecosystem

00:22:37 Introducing "Fit4Science": The Philosophy

00:24:40 News: Inside an Independent Sleep Validation Study

00:27:12 Results: Oura vs. Apple Watch vs. Garmin in Sleep Staging

00:30:51 Biases in Sleep Algorithms: Expectation vs. Reality

00:34:33 Longevity Corner: Why Stephan Got Braces at 34

00:46:59 VO2 Max Study: Testing the Accuracy of Fitness Estimates

00:54:08 Human Efficiency: Energy Expenditure

00:59:50 Height, Confidence, and Biological Advantages

01:03:14 Body Types: Ectomorphs, Mesomorphs, and Endomorphs

01:09:14 Genetic Testing and Hair Loss Prevention

01:11:06 The "Elephant" in the Room: Why Rob Has 8 Bicycles

01:17:14 Risk Assessment: Cycling Safety in Vienna vs. The Netherlands

01:27:10 Funny Science: Why Do Humans Have Body Hair (at the “Rear End”)?

01:31:34 Smells, Pheromones, and Evolutionary "Leftovers"

01:34:59 Closing Thoughts and How to Support the Show

About

Fit for Science is a deep-dive podcast hosted by two biological data scientists, Rob and Stephan, exploring the intersection of research, health tech, and data-driven lifestyle design. We cut through the noise to provide evidence-based systems, layered with practical "N=2" personal experimentation.

Learn more: fitforscience.com

YouTube: @FitForScience

Disclaimer: This podcast represents our own opinions and is for informational purposes only. It does not constitute medical or financial advice or a professional relationship.