Exercise, VO2 max, and longevity | Mike Joyner, M.D

[CronosTempi]

Hate to be pedantic, but science is science. As is so frequent as to be almost unnoticeable, the headline makes claims the study does not deliver on.

1)Some biomarkers and functionality in the exercising twin more closely resembled a younger phenotype. That’s it. Period. The end. This does not prove in any way that this “delivers a younger body”. A younger body would mean all tissues in all respects. Including changes at a cellular level in all tissues, telomere length, elastin etc. Otherwise, no, it’s not a younger body. All they can show are what they showed - those specific markers are closer to younger phenotype, and furthermore that is not proof that even that is “younger”. If I undergo sophisticated plastic surgery to resemble a younger phenotype in an indistinguishable way - eliminate wrinkles, plump up collagen injections, color gray hair etc., this may have all the characteristics of “younger” without actually being younger.

2)The relevant outcome in the claims is lifespan and healthspan. This was not measured. So no claim can be made about it. Lifespan - both are alive, so the outcome is not there to make any claims about - what if the sedentary twin lives longer? As Matt Kaeberlein frequently points out “healthspan” is a tricky measure without formal definition. But it’s worse than that. I bet some folks thought it absurd to imagine the sedentary twin could live longer, because it seems intuitive and obvious that the nominally better healthspan (by some select measures) of the exercising twin should lead to a longer lifespan. The joke’s on them. Please examine the sex paradox. Men live shorter lives IN BETTER HEALTH. Women live longer, but spend more years in worse health, longer beyond the extra years they live compared to males. A man may croak at 80, being in poor health from 75, the woman may croak at 85 being in poor health from 70. Poor healthspan can still result in longer lifespan, so you cannot draw the conclusion “better healthspan equals longer lifespan”. I can show you experiments where voluntary exercise lead to shorter lifespans in strains of rats compared to non-exercising ones. Incidentally (and separately) that’s also true at the extreme end of CR (70%) where exercise actually shortens lifespan. But that’s even true of functionality (more in point 3 below), where CR’d animals are more frail, but live longer and healthier than their stronger, more vigorous and functional ad lib counterparts. Same btw. of castrated animals - not as strong, not as vigorous and functionally capable as intact ones, but live longer and in better health (see also in pets - longer lived, healthier “fixed”). Functionality, vigor and strength do not necessarily translate into either longer lifespan or healthspan (see below).

3)Measures that show superior physical functionality do not nessesarily translate into either health or longevity. Certainly that can be shown easily - bigger muscles, better functionality, bone mass, strength, power physical capability - bad health and short lives: bodybuilders. Before you start talking about steroids etc., stop - you are missing the point. The point is: like in this study - just having a collection of measures and biomarkers, tests of functionality does NOT mean better outcomes. Studies of twin cohorts where one group exercised the other did not and both lived just as long - what about that? This present study hasn’t even shown lifespan in many twins as others have, it’s a single shorter term pair - very weak sauce to make very big claims with no proof. The stupidity of this is really disappointing. You can only make claims about that which you have proven specifically. Here, they’ve proven remarkably little. Physical activity, whether with or without exercise is of the “good enough” variety. If you are an active non-exerciser (as the vast majority of supercentenarians have been - Jeanne Calment didn’t spend one day in a gym or formally “exercised”, lol), you can live as long and healthily as an exerciser (and who knows, maybe longer than the heavy exerciser). Being able to lift 200lbs the day before you die doesn’t mean better health or longevity vs being able to lift only 150 or 100. If your health is “good enough” for unhindered ADL, you are good to go - you can take all those “superior, greater” biomarkers in this study and stuff them, they won’t make a difference worth a hill of beans. If the sedentary twin is “good enough” in his ADL, he’s good to go, he might live just as long and successfully. Prove - prove - otherwise, exaggerated claims not proven mean nothing.

I could go on and on, but my point is - another study big on headline claims backed by nothing but speculation. Stop with the mechanical speculation and deilver outcomes. Nothing is “obvious” unless proven.

[LaraPo]

Lower body fat, lower blood pressure, lower cholesterol, lower glucose, better endurance and metabolic profile and lower BMI, etc., - these are not cosmetic differences — they are major predictors of reduced all‑cause mortality. So the exercising twin looked younger because their physiology was objectively younger. The younger appearance is not superficial — it’s a visible marker of internal resilience.Of course it’s not a guarantee that he will live longer than his other sibling - but it’s obvious that he lives much healthier life and has a good chance to outlive his sibling.

[RapAdmin]

A summary and analysis:

Muscle health and performance in monozygotic twins with 30 years of discordant exercise habits

A pair of 52-year-old male monozygotic twins with 30 years of highly discordant exercise habits offers a rare window into the pure exposomal effects of chronic endurance training. One twin engaged in three decades of competitive endurance running and triathlons (Trained Twin, TT), while the other remained largely inactive (Untrained Twin, UT). The results are profound.

Endurance training yielded massive systemic metabolic benefits: the trained twin exhibited significantly lower resting heart rate, blood pressure, cholesterol, and visceral fat. However, the cost of this extreme endurance adaptation was a reduction in absolute muscle size, decreased voluntary isometric strength, and lower muscle “quality” (measured via ultrasound echo intensity) compared to his inactive, heavier brother. At the cellular level, the trained twin’s vastus lateralis muscle was fundamentally reprogrammed, expressing an extreme 94% slow-twitch (MHC I) fiber composition compared to the untrained twin’s 40%.

This divergence suggests the human cardiovascular and skeletal muscle systems possess far greater environmental plasticity than previous genetic heritability models indicated. While endurance training optimizes the systemic environment for cardiovascular longevity, the data highlights a practical biohacking gap: excessive aerobic volume without dedicated resistance training may compromise absolute mechanical strength and muscle quality as we age.

Context:

• Institution: California State University, Fullerton; San Francisco State University; California State Polytechnic University.
• Country: USA.
• Journal: European Journal of Applied Physiology.
• Impact Evaluation: The impact score of this journal is 2.7, evaluated against a typical high-end range of 0–60+ for top general science, therefore this is a Medium impact journal.

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The Biohacker Analysis

Study Design Specifications

• Type: Clinical In vivo (Case Study).
• Subjects: Human, Monozygotic Twins, Male, N=2 (1 Trained Twin, 1 Untrained Twin).

Mechanistic Deep Dive

• The exposome profoundly shifted nutrient-sensing and metabolic pathways. AMPK α1 and γ1 protein expression were significantly elevated in the trained twin, aligning with chronic endurance-induced AMPK activation. * Muscle fiber remodeling was extreme. The trained twin showed a near-complete conversion to slow-twitch dominance (94% MHC I), driven by downstream translational mechanisms rather than basal mRNA shifts, as MyHC 1 and 2a gene expression were similar between the twins.
• Markers of mitochondrial biogenesis (TFAM) and angiogenesis (VEGFA, eNOS) mRNA were unexpectedly not elevated at baseline in the trained twin. This suggests a physiological ceiling or steady-state adaptation where chronic maintenance downregulates the acute mRNA transcription spikes typically seen in novel training.
• Elevated PAX7 and IGF-1 variants (IGF-1Ea, MGF) in the trained twin indicate heightened satellite cell pools and continuous tissue repair. Conversely, elevated FN14 (a TWEAK receptor) hints at a pro-inflammatory or catabolic stress state in the muscle, which may explain the trained twin’s reduced absolute muscle size and strength.

Novelty

• This is the longest controlled observation (30 years) of highly discordant exercise habits in genetically identical humans. It demonstrates that decades of specific training can push MHC I distribution to extreme limits, resulting in 55% more MHC I fibers than the untrained twin.

Critical Limitations

• Translational Uncertainty: A sample size of N=2 prevents statistical power or broad population-level conclusions, making the data entirely observational. [Confidence: High]
• Confounding Variables: The untrained twin reported consuming a caloric surplus over his estimated Total Daily Energy Expenditure compared to the trained twin. This surplus likely contributed independently to his 43.3% higher visceral adipose tissue. Furthermore, dietary data was collected via a 7-day mobile app recall, which notoriously limits data accuracy. [Confidence: High]
• Methodological Weakness: Muscle quality was assessed using ultrasound echo intensity rather than the gold-standard magnetic resonance imaging (MRI). Additionally, biopsies were taken 48 hours post-testing, meaning acute performance test stress could have confounded resting mRNA levels. [Confidence: Medium]

[RapAdmin]

https://x.com/siimland/status/2053793761436512313?s=20

[RapAdmin]

https://x.com/Alan_Couzens/status/2054233020232847725?s=20

[RapAdmin]

A Good VO2max Charts by: Age, Gender, Sport and Athlete Fitness

[cl-user]

The good news with VO2max is that it is very trainable. For instance here is my Garmin VO2max estimation for the training block for my Boston marathon (on Apr 20th).
Basically it went from 46 to 53 in 8 weeks. Garmin is overestimating VO2max somewhat but that’s the relative increase which is interesting.

[RapAdmin]

I Tested Every Popular HIIT Protocol So You Don’t Have To

- YouTube

I. Executive Summary

This video evaluates the physiological adaptations, metabolic parameters, and practical adherence rates of popular high-intensity interval training (HIIT) protocols. The central thesis is that while all structured interval training improves cardiorespiratory fitness, specific variations in interval duration and mechanical intensity yield different outcomes in VO2​ max expansion, mitochondrial biogenesis, and long-term behavioral compliance.

The speaker categorizes protocols based on their metabolic demands, differentiating between supramaximal sprint interval training (SIT) and longer, aerobic-focused high-intensity intervals. Supramaximal protocols like the classical Tabata method demand workloads reaching 170% of VO2​ max power output. While highly efficient in elite athletic cohorts, these methods carry a low adherence rating for average populations who cannot accurately gauge or sustain supramaximal effort, often resulting in sub-optimal pacing.

Conversely, protocols featuring longer intervals at high volumes demonstrate superior clinical efficacy for structural cardiovascular remodeling. The Norwegian 4x4 protocol (4 minutes at 85% to 95% maximum heart rate) is highlighted for its ability to optimize the time spent at peak cardiac stroke volume, effectively counteracting age-related arterial and myocardial stiffness.

For the average individual, the Gibala method (1 minute at 100% peak power followed by 75 seconds of recovery) emerges as the most balanced option, delivering robust mitochondrial adaptations with a manageable psychological barrier.

The analysis also reviews low-volume variations like Reduced Exertion HIIT (REHIT) and Vigorous Intermittent Lifestyle Physical Activity (VILPA), or “exercise snacks.” While REHIT lacks the volume necessary to drive significant VO2​ max adaptations in conditioned individuals, brief 1- to 2-minute bursts of daily activity (VILPA) correlate with a 38% to 40% reduction in all-cause mortality. Ultimately, the video establishes that the selection of a HIIT protocol should depend on an individual’s baseline training status, emphasizing that interval volume and duration are more reliable drivers of cardiovascular longevity than extreme, brief power outputs.

II. Insight Bullets

• Cardiovascular Rejuvenation Kinetics: Structured high-intensity interval training drives rapid improvements in stroke volume and myocardial elasticity, showing the potential to structurally reverse age-related cardiac decline [[00:00], [07:46]].
• Supramaximal Power Misconceptions: Supramaximal effort (such as Tabata’s 170% VO2​ max workload) scales based on peak power output wattage, not maximum heart rate, creating an extreme anaerobic barrier that most non-athletes cannot safely or accurately achieve [[03:00], [04:05]].
• Pacing Degradation in Short Intervals: Untrained individuals attempting short, ultra-intense protocols like Tabata typically fail to hit true supramaximal thresholds, inadvertently executing sub-optimal, half-hearted intervals that diminish potential adaptations [[03:34], [04:14]].
• Interval Duration Superiority: Meta-analytic data indicates that while short intervals (≤30 seconds) provide basic fitness adaptations, maximizing VO2​ max requires longer intervals (>2 minutes) and sustained high volumes (>15 minutes total) over 4 to 12 weeks [[06:31], [06:51]].
• The Norwegian 4x4 Mechanism: The Norwegian protocol maintains the heart rate within an intensive 85% to 95% max threshold for a cumulative 16 minutes, maximizing the time spent at peak cardiac output to drive superior central cardiovascular adaptations [[06:05], [07:20]].
• The Multimodal Reversal Blueprint: Reversing the structural age of the heart requires a progressive, multimodal training matrix that layers high-intensity 4x4 intervals on top of a foundational base of low-intensity Zone 2 cardio and regular resistance training [[07:46], [08:04]].
• Diminishing Returns of Sprint Volume: In sprint interval training (SIT), executing 2 to 3 all-out sprints is sufficient to stimulate maximum VO2​ max adaptations, while scaling to 4 to 7 sprints increases neurological fatigue with diminishing metabolic returns [[09:46], [10:06]].
• Time-Efficiency Efficacy Parity: Short-duration SIT protocols (30 minutes cumulative weekly volume) can match the VO2​ max expansions, insulin sensitivity improvements, and mitochondrial biogenesis scores achieved by 150 minutes of moderate-intensity continuous cardio [[10:06], [10:34]].
• SIT as Neuromuscular Skill: All-out sprinting should be coached as a technical, neuromuscular skill requiring strict running form and sprint mechanics rather than a simple tool for heart rate elevation [[11:00]].
• The Gibala Sustainability Sweet Spot: The Gibala method balances intensity and duration by pairing 1-minute efforts at 100% peak power with 75-second recovery periods, providing an accessible and sustainable protocol for non-athletes [[11:29], [12:16]].
• The Minimum Effective Sprint Volume: Reduced Exertion HIIT (REHIT) protocols utilizing only one or two brief sprints fail to provide sufficient training volume to expand VO2​ max in athletic or average-conditioned individuals [[13:54], [14:07]].
• The 30/30 Lactate Curve: Performing high-frequency 30-second intervals at 90% maximum power output generates lower systemic lactate levels and allows for greater total oxygen consumption than sprinting at 100% capacity [[14:46], [15:10]].
• VILPA Mortality Reduction: Accumulating 1 to 2 minutes of Vigorous Intermittent Lifestyle Physical Activity (VILPA), or “exercise snacks,” three times daily correlates with a 38% to 40% drop in all-cause mortality and an approximate 48% reduction in cardiovascular mortality [[16:10], [16:22]].
• Exercise Snack Glycemic Control: Engaging in brief exercise snacks throughout the day triggers acute, insulin-independent glucose transporter type 4 (GLUT4) translocation, improving glycemic control in insulin-resistant populations [[16:30]].
• Sauna-Induced Workout Mimicry: Regular thermal exposure via sauna bathing or far-infrared blankets elevates core temperature and heart rate to mimic the cardiovascular strain of moderate workouts, correlating with a 63% reduction in sudden cardiac death risk [[04:54], [05:14]].
• Contextual HIIT Dependency: Structured HIIT is highly valuable as a time-efficient conditioning tool for individuals lacking a cardiovascular routine, but it becomes redundant for athletes already maintaining a high volume of foundational Zone 2 cardio [[17:00]].

IV. Actionable Protocol

High Confidence Tier (Backed by Level A/B Human Evidence)

• Deploy the Gibala Protocol for Practical Conditioning: To expand VO2​ max and stimulate mitochondrial biogenesis without extreme neurological fatigue, perform the Gibala method three times weekly: complete a 1-minute interval at 100% peak power output, followed by 75 seconds of active recovery, repeated for 8 to 12 cycles [[11:29], [11:50]].
• Incorporate Lifelong Exercise Snacks (VILPA): Intercept sedentary desk behavior by introducing 1- to 2-minute bursts of vigorous physical activity (such as rapid stair climbing or stationary bodyweight squats) three times daily to support glycemic control and reduce all-cause mortality risk [[16:10], [16:30]].
• Optimize Sprint Volume Limits: When performing sprint interval training (SIT), cap all-out efforts at 2 to 3 rounds of 20-second sprints with 2 minutes of total rest between bouts. Avoid executing more than 4 sprints per session to prevent excessive fatigue and diminishing returns [[09:46]].
• Utilize Regular Thermal Therapy: Incorporate 20-minute sauna or far-infrared blanket sessions at ≥70∘C to lower arterial stiffness, enhance endothelial function, and leverage the cardiovascular safety benefits associated with heat shock responses [[04:54], [05:38]].

Experimental Tier (Level C/D Evidence with High Safety Margins)

• Deploy the Norwegian 4x4 for Structural Cardiac Remodeling: Conditioned individuals seeking to improve myocardial elasticity should implement the Norwegian method once every two weeks: perform 4 minutes of intense exercise maintaining 85% to 95% of maximum heart rate, followed by 3 minutes of low-intensity recovery, repeated for 4 rounds [[06:05], [09:03]].
• Execute the Multi-Modal Longevity Matrix: To structurally rejuvenate aging cardiac tissue, build a long-term plan that balances two weekly HIIT interval sessions with one long low-intensity base session (>60 minutes), one moderate cardio session (30 minutes), and two structured resistance-training workouts [[08:04]].

Red Flag Zone (Claims Contradicted by Data or Lacking Safety Evidence)

• Avoid Classical Tabata Without Precise Wattage Tracking: Do not attempt the traditional Tabata method using estimated heart rate zones. Without exact power output tracking on a calibrated ergometer to ensure a true 170% VO2​ max workload, the protocol loses its intended efficacy and results in premature fatigue [[03:00], [04:05]].
• Do Not Rely on REHIT for Conditioned Athletes: Avoid using Reduced Exertion HIIT (REHIT) as a primary training stimulus if you possess average or above-average fitness. Protocols limited to one or two short sprints do not provide the necessary training volume to drive further cardiovascular adaptations in conditioned populations [[13:54], [14:07]].

V. Literature Verification & Methodological Context

The exercise physiology and clinical metrics referenced regarding interval durations and metabolic responses are consistent with established athletic and geroscience research.

• The Tabata Supramaximal Framework: The host’s breakdown of the Tabata method correctly identifies the parameters from the original study published in Medicine and Science in Sports and Exercise. The trial verified that 4 minutes of ultra-intense intervals at 170% of VO2​ max power output significantly expanded both aerobic and anaerobic capacities in speed skaters, a protocol distinct from common low-intensity commercial adaptations (Tabata et al., 1996).
• Interval Duration and VO2​ max Adaptations: The preference for longer intervals to drive maximum adaptations is validated by large-scale exercise reviews. A comprehensive meta-analysis published in Sports Medicineconfirmed that while short-duration intervals elicit rapid initial conditioning, optimizing central cardiac stroke volume and expanding absolute VO2​ max requires longer intervals (>2 minutes) paired with high collective volumes (Wen et al., 2019).
• VILPA and Mortality Outcomes: The epidemiological survival data linked to “exercise snacks” stems from a major cohort evaluation published in Nature Medicine. Utilizing accelerometer data from over 25,000 non-exercisers, researchers verified that accumulating 3 to 4 daily 1-minute bursts of vigorous intermittent lifestyle physical activity (VILPA) was associated with an approximate 40% reduction in all-cause mortality and up to a 49% reduction in cardiovascular-related mortality (Stamatakis et al., 2022).

Methodological Caveat: Although implementing high-volume protocols like the Norwegian 4x4 or the Gibala method results in rapid expansions of VO2​ max and localized mitochondrial density, these interventions impose significant central nervous system and structural stress. Unconditioned individuals or those with underlying subclinical cardiovascular damage must undergo a clinical assessment prior to initiating workloads exceeding 85% of their maximum heart rate.