THE SIGNAL
Issue 002 - March 27, 2026 - SAUNA SCIENCE
THE SIGNAL
Scientific Intelligence for Men's Health & Performance
A FeltovichFit Publication · Collegium of Order & Flow
Week of March 22–27, 2026 · Issue 002 · Andy Feltovich, CISSN · CSCS · StrongFirst Elite
Each week, The Signal cuts through the noise in health, performance, and science:
- What to watch?
- What to ignore?
- What's "news" but isn't new?
This week's deep dive is sauna science — what the evidence actually says, what it doesn't, and why the answer is more nuanced than the headlines suggest.
The Signal analyzes each topic with the IICE Framework:
- Incentives. Who is being asked to believe what? Why? And why now?
- Impact. Does it move the needle?
- Context. How does it relate to other evidence within the discipline and across disciplines, both currently and historically?
- Epistemic Authority. Is the argumentation sound and valid?
▶ What to Watch
Watch 1
GLP-1 / Ozempic: The Compounding Window Closes
Why It Matters
Hims & Hers struck a deal with Novo Nordisk on March 9 to carry branded Ozempic and Wegovy, simultaneously ceasing promotion of compounded alternatives. FDA had issued 30 warning letters to telehealth compounders on March 3 for misleading marketing. The compounded GLP-1 pipeline — which had given millions access to semaglutide at a fraction of branded cost — is closing. Anyone currently on a compounded telehealth GLP-1 product faces near-term supply disruption and a significant price increase.
Signal Strength
The sequence is now complete: FDA declared the semaglutide shortage resolved in February, which triggered the legal basis for enforcement. The 30 warning letters followed. The Hims/Novo deal is the commercial capitulation that confirms the regulatory direction and further bolsters pharma's competitive moat. The science is unchanged and the side-effects continue to mount, including muscle loss: roughly 40% of weight lost on GLP-1 therapy is lean mass. Structured resistance training and nutrition remains a mandatory adjunct, not an option.
Prediction
The GLP-1 market will consolidate around branded products at higher price points. Telehealth platforms that built their business models on compounded alternatives will restructure. The patients who will be most affected are those who cannot afford the transition to branded products — a significant access and equity story that has not yet received proportionate coverage. The resistance training and nutrition adjunct protocol is not optional and will become a standard of care as the evidence base widens. See Deep Dive in Issue 001 for more.
Headlines: BioPharma Dive, Mar 9, 2026 · FDA, Mar 3, 2026
Watch 2
Wearables + HRV / Sleep Tracking: The Interpretation Gap
Why It Matters
A viral wearable-data study claimed that 156 minutes of low-intensity movement equals 1 minute of vigorous exercise — a classic case of confusing a population-level description with an individual training prescription. The gap between what wearable data says and what it means is widening faster than the devices are improving.
Signal Strength
The sleep wearable market reached $70 billion in 2025 and is growing at 6.7% annually, but device accuracy has largely plateaued. ACSM ranked wearable technology the #1 fitness trend for the fifth consecutive year.
Prediction
The future is not in better devices — it's in better use and interpretation, including avoiding the stress and anxiety that the data can cause, such as orthosomnia — neuroses caused by worrying about sleep data (see Deep Dive in Issue 001 for details). The practitioners who can translate a readiness score into a sound training decision and counsel clients and patients on interpretation and proper use will own the next decade of performance coaching. The device companies will not solve this — their incentive is to get you on the app, not counsel you in proper use and interpretation.
Headlines: Peter Attia MD, Jan 17, 2026
Watch 3
Testosterone / Men's Hormonal Health: The Looksmaxxing Shadow
Why It Matters
The NYT Daily ran a piece on March 22 on "looksmaxxing" — the online male subculture of extreme appearance optimization including steroid and hormone use, jawbone manipulation, and aesthetic injection procedures. A separate AAOS conference study of 13,250 patients found that testosterone users undergoing total knee replacement had materially higher rates of postoperative complications including blood clots, infections, and joint instability. TRT prescriptions grew from 7.3 million in 2019 to over 11 million in 2024.
Signal Strength
The exec cohort is not hammering their jawbones. But they share the underlying anxiety: male body image, hormonal optimization, the gap between what they want and what aging delivers. The looksmaxxing story is the low-end cultural expression of the same demand signal driving TRT market growth. The demand for rigorous, unconflicted analysis of this space has never been higher.
Prediction
Lifestyle interventions — sleep, progressive strength training, body composition, stress management — move the needle meaningfully before TRT is warranted, and for most men in this cohort, that is the correct starting point. Dr. Arny Ferrando, leading expert on men's aging and TRT, noted in my podcast interview with him that the downside risks to health and performance are in not supplementing with TRT — but the question is when. How you feel — fatigue, performance, and libido — should drive the TRT decision, not just the lab report. This issue is ripe for a Deep Dive — stay tuned (see Additional Resources below for the full podcast episode).
Headlines: NYT The Daily, Mar 22, 2026 · AAOS / PR Newswire, Mar 2, 2026
✕ What to Ignore
Ignore 1
RFK / Food Dyes Ban
Why It's Spiking
Slight deceleration this week. West Virginia's ban is in effect; roughly 40% of packaged food companies have made voluntary reformulation commitments. Political momentum continues but is no longer generating novel scientific claims.
Why It's Noise
Reuters confirmed that most companies making voluntary commitments have not actually reformulated. The behavioral literature on synthetic dyes in adults at real-world exposure levels is essentially nonexistent. Regulatory action does not equal scientific validation. If you eat real food, this problem is already solved.
What Would Change My Mind
Double-blind RCTs showing consistent behavioral or physiological effects at real-world exposure levels in adults — not children, not at 10x normal exposure, not in rodent models.
Headlines: Reuters, Jan 28, 2026 · KFF Health News
Ignore 2
Cold Plunge / Ice Bath: The Atlantic Correction
Why It's Spiking
The Atlantic published a major skeptical piece on March 19 arguing that wellness influencers are promoting cold plunging for entirely the wrong reasons. The piece is generating significant discussion across health and fitness media.
Why It's Noise
The Atlantic's central finding is correct and worth understanding: cold water immersion immediately post-resistance training reduces muscle growth by approximately 20%. The root cause is a fundamental confusion between adaptation and performance recovery — between the targeted, strategic inflammation that elicits training adaptations and the systemic, chronic inflammation that is the root of most modern industrial diseases (MIDs). If you need to recover quickly to perform again — between competitions, for example — cold plunging works. If you are training to get bigger, faster, or stronger, it does not. The one well-supported benefit of cold exposure is mood and mental resilience, evidenced by a Dutch study of 3,000+ participants showing 30% fewer missed workdays from cold shower exposure. The immunity, brown fat activation, and longevity claims are substantially unsupported. The cold plunge equipment industry is selling you something.
What Would Change My Mind
Large-scale RCTs demonstrating that the muscle growth inhibition finding does not replicate, or evidence of other benefits that would move cold plunging from "feels good — is good" to a concrete, evidence-based recommendation.
Headlines: The Atlantic, Mar 19, 2026
Ignore 3
Slow Wellness / Over-Optimization Backlash
Why It's Spiking
Fading. The Global Wellness Summit named it a 2026 trend, luxury brands are repositioning around "rest as performance," and TikTok somatic content continues to circulate. The looksmaxxing story has now displaced this as the primary male body-culture narrative.
Why It's Noise
The Blue Zone literature confirms that high-longevity populations are characterized by high-frequency, low-intensity activity and strong social bonds as permanent, organic lifestyle backdrops — not micro-dosed, expensive retreats. The product being sold here is expensive experiences and aesthetic repositioning.
What Would Change My Mind
A RCT or even a respectable epidemiological survey study showing efficacy on par with known needle-movers like sleep, exercise, and nutrition — or anecdotal evidence from blue zones supporting deliberate, paid-for wellness experiences as distinct from organic lifestyle patterns.
Headlines: Global Wellness Summit, Jan 27, 2026
↻ What's "News" but Isn't New
Not New 1
Protein + Resistance Training: The Anabolic Resistance Problem
Current Trend
A systematic review published in Biomolecules (Jan 2026) synthesizing RCTs on protein supplementation combined with resistance exercise for sarcopenia biomarkers is now circulating in mainstream media — Fox News, Harvard Health, NCOA. "Anabolic resistance" is the emerging consumer-facing concept.
Historical Analog
The concept of anabolic resistance — that muscle protein synthesis in older adults requires a larger protein dose to achieve the same response as in younger adults — was described in the academic literature around 2000. The federal RDA of 0.8 g/kg/day was set as a deficiency-prevention floor, not a performance target. This gap has been known for over two decades.
The Signal
I've been calling this out since my protein YouTube video in 2021 (see Additional Resources below). If you follow my recommendation — 1.6+ grams of protein per kilogram of bodyweight per day for 40+ resistance-training males, which should be all 40+ males — you have nothing to worry about. For healthy individuals, the downside risk is to underconsumption. The only side effects from eating more protein are better body composition, recovery, and performance, as explained in Dr. Jose Antonio's ISSN Position Stand Presentation on protein (see Additional Resources below).
Headlines: Biomolecules / PMC, Jan 27, 2026 · Fox News / UCLA Health, Mar 4, 2026
Not New 2
Fibermaxxing — Fiber Is the New Protein
Current Trend
The mainstream media wave crested the week of March 8–16 with Tufts University coverage, U.S. News, and multiple health outlets. Social volume is normalizing. The GLP-1 hook — that natural fiber stimulates endogenous GLP-1 production — received the most traction.
Historical Analog
The core fiber science — LDL reduction, blood sugar stabilization, gut microbiome support — has been established since Burkitt and Trowell in the 1970s. FDA dietary fiber recommendations have moved negligibly in 30 years.
The Signal
Post-peak — and good riddance. The GLP-1-fiber mechanism (short-chain fatty acids from fermentation triggering L-cell GLP-1 release) is a genuinely new research thread, but it is mechanistic data, not yet a clinical protocol. If you eat a whole-foods diet, fiber takes care of itself. Excessive fiber can impede nutrient absorption, slow gastric emptying (consequential for training), and cause gastric distress. Artificial "fiber" is a full-stop no-go: some FDA-permitted compounds labeled as fiber have been implicated in painful bezoars — indigestible masses that can require surgery in extreme cases. See Additional Resources below.
Headlines: ScienceDaily / Tufts, Mar 8, 2026
Not New 3
Sauna / Heat Therapy: The Science Is Older Than You Think
Current Trend
NPR ran a two-part series on sauna science (March 6 and March 11), followed by The Atlantic's cold plunge skeptic piece (March 19) which explicitly argued that heat is superior to cold for recovery, cardiovascular adaptation, and muscle health. Two weeks of major media coverage, with the sauna signal strengthening rather than plateauing.
Historical Analog
The landmark cardiovascular study — Laukkanen et al., JAMA Internal Medicine 2015 — followed 2,315 Finnish men for approximately 20 years and found that 4–7 sauna sessions per week were associated with a 40–60% lower risk of cardiovascular disease and all-cause mortality vs. once weekly. The Finnish sauna tradition is centuries old. The population data has been available for decades.
The Signal
See Deep Dive below. Saunas likely benefit the people who use them and claim to benefit from them, but the evidence used to support their use is more varied and nuanced than sauna proponents would have you believe. Problems with the evidence include self-selection — who can use them and who chooses to use them — as well as several other lifestyle factors correlated with sauna use. Saunas ultimately fall under feels-good-is-good: if you use them and like them, keep using them — as a complement to a healthy lifestyle, not a substitute for one.
Headlines: NPR, Mar 6, 2026 · The Atlantic, Mar 19, 2026
■ Deep Dive — Issue 002
Saunas: Feels Good — Is Good (But Not for the Reasons You Think)
Saunas are probably benefitting the people who're using them—but not for the reasons probably thought and not because of any "science" as most people think of the word.
People don't use science to think—they use it to avoid thinking. "What does the science say about saunas?" is the wrong starting point for two reasons: (1) we haven't defined what question we're attempting to answer with "science," and (2) science exists on a continuum.
The first question is important because "Perception… constructs rather than records reality" [1]. We don't see the world and then think about it. We think about it—and that determines what we see. Framing matters.
The second issue is important because a narrow definition of "science" privileges what's easy to measure over what might actually matter. Science is the study of cause and effect. At some arbitrary point, with enough rulers and tape measures, enough precision—real or perceived—evidence is ordained "Science" with a capital "S." My cat meows and I feed him. My cat has identified cause and effect. My cat is a scientist—effective if not sophisticated.
Back to the first issue, proper inquiry starts with three questions:
- What problem are we trying to solve?
- What systems are involved?
- What is the available evidence: RCTs, epidemiological surveys, population data, historical priors, expert best practices?
People use saunas to look, feel, recover, and perform better. The answers to the second and third questions are more complicated. This analysis will take a bottoms-up approach, starting with the cell.
There is evidence that saunas improve vasodilation, arterial compliance, parasympathetic tone, and upregulate (increase) heat shock proteins [2–5]:
- Improved vasodilation and arterial compliance via increases in the vasodilator nitric oxide (NO), both by upregulating NO and by reducing the reactive oxidative species that degrade it—important for cardiovascular health [3, 5]
- Improved parasympathetic nervous system tone—the rest-and-digest counterpart to the fight-or-flight sympathetic nervous system—as evidenced by decreased heart rate and improved heart rate variability after sauna exposure—important for stress management [2, 5]
- Upregulated heat shock proteins, resulting in more of those proteins to both fix damaged proteins and prevent further protein damage—important for resiliency, recovery, and longevity [3]
The evidence for those cellular mechanisms is convincing but comes with several caveats. The cardiovascular benefits are confined to the heart and blood vessels—pumps and pipes. Saunas won't increase the aerobic capacity of muscles—the engine—and therefore aren't a substitute for aerobic exercise. Also, those studies only measure acute responses immediately after sauna use. Whether those are chronic, lasting adaptations remains to be seen. Last, there are lingering questions about the optimal duration, temperature, and type of sauna use.
At the epidemiological survey level, the seminal—and over-interpreted and abused—study is the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) [6]. According to the study, all-cause CVD mortality decreased from 49.1% in men using the sauna once weekly to 37.8% in those using it 2–3 times per week and 30.8% in those using it 4–7 times per week over a median 20.7-year follow-up. Like all survey studies, validity issues and confounders abound:
- The study relied on a single, subjective survey at baseline to assess sauna use and risk factors, with no follow-up assessments.
- People misremember, misreport, and behaviors change over time. The study had no way to account for that.
- Sauna users are by definition healthy enough to go to the sauna [7] and more likely to be health-conscious than the general population—the classic third-variable problem—a residual confounder even after controlling for socioeconomic status.
- There was no randomization, no intervention, and only cursory treatment of causal mechanisms, with no explicit testing.
The study is an important—but by no means dispositive—data point. Everyone repeat after me: "correlation does not mean causation!"
Population data and historical priors are some of the more informative—and overlooked—evidence in favor of sauna use. Taleb emphasizes the importance of examining the persistence of practices over time, the Lindy effect, and prioritizing what people do over what they say, a Popperian focus on falsification through reality [8]. Finnish sauna use is pervasive and Finns are the happiest people in the world by at least one account [9]. Identifying patterns that lead to happiness is analogous to Ben Greenfield's work in identifying blue zones—regions and populations in which people live long, healthy lives [10]. In blue zones, longevity is not explained by a single variable, but by consistent patterns that encompass: diet, movement, social bonds, low stress, moderation, and some form of spiritual grounding.
The pattern for Finnish happiness encompasses: high social trust, strong social support, low corruption, a sense of security, access to nature, a slower pace of life, low hierarchy—and saunas—so much so that the article suggests visiting a sauna as a first acquaintance with Finnish life, evidence that saunas are an integral part of a broader happiness ecosystem—not an aftermarket lifestyle bolt-on, hack, or cheat code that works in isolation.
Expert best practices include sauna use too. Wrestling legend Dan Gable swore by their efficacy for both him and his teams. He noted improved recovery between intense training sessions, mood enhancement, and team bonding [11, 12]—not just socializing, which likely has neurological benefits in itself [13]—but also something deeper—"truth serum," as he termed it, conversations about effort, performance, and accountability that didn't—maybe couldn't—happen elsewhere. Another likely benefit of post-practice sauna use that Gable didn't mention is memory consolidation and learning, which benefits from what cognitive scientists term "wakeful rest," doing nothing without interference after learning, important for skill acquisition and retention [14].
There are several other intangibles that likely contribute to the healthy benefits of sauna use. Saunas are usually quiet. Golden makes a strong argument that the incessant mechanized noise in modern societies is detrimental to health [15]. Use of cell phones and electronic devices in Finnish saunas is strictly forbidden or at least heavily stigmatized [7]. Unplugged makes a strong argument for the health benefits of electronic fasting and mobile-device detoxing [16], respites from the ubiquitous electronic devices of modern life. Antifragile argues that any physical, environmental stressor—which includes heat—might elicit adaptations that improve resiliency and durability [17]. The heat doesn't even need to come from saunas. Hot-weather exposure and training might elicit similar adaptations [7], as might the Japanese practice of hot springs and hot baths, population evidence from another high-longevity population.
In addition to the inclusion of all relevant evidence, there's a question of interpretation. If an intervention fails to reach statistical significance—a threshold that is itself frequently misunderstood and misused [18]—there are at least two possible conclusions: either the intervention truly has no effect, or its effects are heterogeneous, benefiting some test subjects but not others. A failure to detect a statistically significant effect at the group level does not preclude meaningful responses at the individual level, particularly in domains characterized by high inter-individual variability. Evidence on post-exercise recovery modalities, for example, shows mixed and context-dependent effects across individuals and interventions [19, 20]. In that light, the absence of strong statistical support should be interpreted cautiously—not as proof of ineffectiveness, but as a limitation of inference.
The conclusion is: feels good—is good. If you enjoy saunas, continue to use them. If you've never used them, they're worth a try based on the preponderance of evidence, especially when incorporated into the lifestyles and other practices described herein and not treated as an extraneous lifestyle bolt-on, hack, or cheat code.
■ References · Further Reading · Additional Resources
References
[1] R. J. Heuer, Psychology of Intelligence Analysis. Echo Point Books & Media, LLC, 2024.
[2] E. Lee et al., "Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial," American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, vol. 323, pp. R289–R299, 2022. https://doi.org/10.1152/ajpregu.00076.2022
[3] M. Iguchi et al., "Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans," Journal of Athletic Training, vol. 47, no. 2, pp. 184–190, 2012.
[4] J. Hussain and M. Cohen, "Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review," Evidence-Based Complementary and Alternative Medicine, vol. 2018, p. 1857413, 2018. https://doi.org/10.1155/2018/1857413
[5] J. A. Laukkanen, T. Laukkanen, and S. K. Kunutsor, "Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence," Mayo Clinic Proceedings, vol. 93, no. 8, pp. 1111–1121, 2018. https://doi.org/10.1016/j.mayocp.2018.04.008
[6] T. Laukkanen et al., "Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events," JAMA Internal Medicine, vol. 175, no. 4, pp. 542–548, 2015. https://doi.org/10.1001/jamainternmed.2014.8187
[7] B. Gifford, Hotwired, First Edition. New York: HarperCollins, 2026.
[8] N. N. Taleb, Skin in the Game: Hidden Asymmetries in Daily Life. New York: Random House, 2018.
[9] L. Galloway, "The world's happiest countries for 2026 – and what they get right," BBC Travel, 2026.
[10] B. Greenfield, Boundless: Upgrade Your Brain, Optimize Your Body & Defy Aging. Las Vegas: Victory Belt Publishing Inc., 2025.
[11] D. Gable and K. Klingman, A Wrestling Life 2: More Inspiring Stories of Dan Gable. Iowa City: University of Iowa Press, 2017.
[12] FinnleoSaunas, "Dan Gable – Sauna, Sports, and Recovery," interview Jul. 20, 2017. https://www.youtube.com/watch?v=0FEmKWMOlUo
[13] B. Rein, Why Brains Need Friends: The Neuroscience of Social Connection. New York: Avery, 2025.
[14] M. Dewar et al., "Brief Wakeful Resting Boosts New Memories Over the Long Term," Psychological Science, 2012. https://doi.org/10.1177/0956797612441220
[15] J. T. Zorn and L. Marz, Golden: The Power of Silence in a World of Noise. New York: Harper Wave, 2022.
[16] B. MacKenzie, A. Galpin, and P. White, Unplugged. Las Vegas: Victory Belt Publishing, 2017.
[17] N. N. Taleb, Antifragile: Things That Gain from Disorder (Incerto). New York: Random House, 2012.
[18] S. T. Ziliak and D. N. McCloskey, The Cult of Statistical Significance. Ann Arbor, MI: University of Michigan Press, 2008.
[19] J. Hoffmann, M. Israetel, and M. Davis, Recovering from Training: How to Manage Fatigue to Maximize Performance. Renaissance Periodization, 2020.
[20] O. Dupuy et al., "An Evidence-Based Approach for Choosing Post-exercise Recovery Techniques," Frontiers in Physiology, vol. 9, p. 403, 2018. https://doi.org/10.3389/fphys.2018.00403
Further Reading
► R. J. Heuer, Psychology of Intelligence Analysis. Echo Point Books & Media, 2024.
The foundational text on analytical tradecraft. The framing argument in the sauna article — "perception constructs rather than records reality" — is the opening thesis. Required reading for anyone who makes decisions under uncertainty.
Hardcover Paperback Audible
► B. Gifford, Hotwired, First Edition. HarperCollins, 2026.
The source book for the Atlantic cold plunge piece and a significant source for this issue's sauna analysis. Gifford's argument — that heat is generally superior to cold for recovery, and that the "longevity bros" are cold plunging for the wrong reasons — is well-sourced and worth reading in full.
Hardcover Kindle Audible
► N. N. Taleb, Skin in the Game: Hidden Asymmetries in Daily Life. Random House, 2018.
The Lindy effect and the skin-in-the-game principle — referenced in the sauna article — are fully developed here. Taleb's framework for evaluating the persistence of practices as evidence of their robustness is one of the most useful heuristics in this publication's analytical toolkit.
Hardcover Paperback Audible Kindle
► B. Greenfield, Boundless: Upgrade Your Brain, Optimize Your Body & Defy Aging. Victory Belt Publishing, 2025.
Greenfield's blue zone synthesis and recovery protocol compendium. Treat as a reference and cross-check against primary literature — but the breadth of modalities covered is unmatched in the popular literature.
Kindle
► D. Gable and K. Klingman, A Wrestling Life 2: More Inspiring Stories of Dan Gable. University of Iowa Press, 2017.
The Dan Gable sauna passages cited in this issue's deep dive. Gable's use of sauna for recovery, team bonding, and what he called "truth serum" conversations is one of the more compelling expert-practice data points in the sauna literature.
Hardcover Paperback Kindle Audible
► B. Rein, Why Brains Need Friends: The Neuroscience of Social Connection. Avery, 2025.
Rein's argument that social connection is not a nice-to-have but a biological need with measurable neurological correlates directly supports the "truth serum" observations in the Gable section.
Hardcover Kindle Audible
► J. T. Zorn and L. Marz, Golden: The Power of Silence in a World of Noise. Harper Wave, 2022.
The argument that mechanized noise is detrimental to health — and that the quiet of a sauna is not incidental but part of its mechanism — pairs directly with the Unplugged argument below.
Hardcover Paperback Kindle Audible
► B. MacKenzie, A. Galpin, and P. White, Unplugged. Victory Belt Publishing, 2017.
The health benefits of electronic fasting and mobile-device detoxing — the Finnish sauna prohibition on phones is not merely cultural, it is mechanistically significant. MacKenzie, Galpin, and White make the case that deliberate disconnection is a recovery modality in its own right.
Hardcover Kindle
► N. N. Taleb, Antifragile: Things That Gain from Disorder (Incerto). Random House, 2012.
The hormesis argument — that controlled stressors including heat elicit adaptations that improve resiliency — is fully developed here.
Hardcover Paperback Kindle Audible
► S. T. Ziliak and D. N. McCloskey, The Cult of Statistical Significance. University of Michigan Press, 2008.
The methodological argument underlying the final section of the sauna deep dive — that a failure to reach statistical significance is not proof of ineffectiveness, but a limitation of inference. This book is the definitive take-down of p-value worship and is relevant to every evidence evaluation in this publication.
Hardcover Paperback Kindle
► J. Hoffmann, M. Israetel, and M. Davis, Recovering from Training: How to Manage Fatigue to Maximize Performance. Renaissance Periodization, 2020.
The recovery modality literature cited in the Deep Dive. Mixed and context-dependent effects is the honest summary; this book provides the most rigorous framework currently available for thinking about recovery interventions.
Paperback Kindle Audible
Additional Resources
■ ISSN Position Stand on Protein — Dr. Jose Antonio conducted the seminal work dispelling myths about protein's dangers to health, especially kidney health, and remains a leading authority on protein requirements for active individuals.
■ Protein: Friend or Foe — A 2021 video from the FeltovichFit YouTube series explaining the inadequacy of then-current protein recommendations and why the prevailing guidance was insufficient for active adults over 40.
■ Fiber Frenzy — A. Feltovich, FeltovichFit, LinkedIn. An explanation of why the fibermaxxing trend is nutritional theater for anyone already eating whole foods — and why artificial fiber products are a full-stop no-go, with notes on bezoar risk from FDA-permitted fiber compounds.
■ The Signal Podcast with Dr. Arny Ferrando — Host Andy Feltovich and leading expert Dr. Arny Ferrando dig into TRT, men's aging, and the evidence behind hormonal optimization.
Additional Resources — Social & Handles
■ FeltovichFit Podcast — Spotify
■ Glossary of Terms & Acronyms
AAOS — American Academy of Orthopaedic Surgeons
ACSM — American College of Sports Medicine
CVD — Cardiovascular Disease
FDA — U.S. Food and Drug Administration
GLP-1 — Glucagon-Like Peptide-1 — a gut-derived hormone that regulates appetite and blood sugar; the mechanism behind semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound)
HPA axis — Hypothalamic-Pituitary-Adrenal axis — the central stress-response system governing cortisol release
HRV — Heart Rate Variability — millisecond variation between heartbeats; a proxy for autonomic nervous system recovery status
HSP — Heat Shock Proteins — molecular chaperones upregulated by heat stress that repair damaged proteins and protect against further damage
IICE — Incentives, Impact, Context, Epistemic Authority — The Signal's analytical framework for evaluating health claims
KIHD — Kuopio Ischemic Heart Disease Risk Factor Study — the landmark Finnish epidemiological study underpinning most sauna cardiovascular claims
MIDs — Modern Industrial Diseases — a Feltovich neologism for diseases pervasive in modern industrial societies and largely unknown outside them (e.g., type 2 diabetes, obesity, chronic systemic inflammation)
NO — Nitric Oxide — a vasodilator that improves blood flow; upregulated by sauna-induced heat stress
Orthosomnia — Anxiety and obsessive behavior caused by excessive focus on wearable sleep data; a documented clinical phenomenon first described in 2017
RCT — Randomized Controlled Trial — the highest-quality study design for establishing causality
TRT — Testosterone Replacement Therapy
VO₂max — Maximum oxygen uptake — the strongest independent predictor of all-cause mortality per Mandsager et al. (JAMA, 2018)
Collegium of Order & Flow
Frameworks for a Fallen World
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THE SIGNAL is produced by Andy Feltovich — CISSN · CSCS · StrongFirst Elite
A FeltovichFit Publication · Collegium of Order & Flow · Not medical advice.