Longevity and Health Span Tips
Longevity and Health Span Tips offer concise, easy-to-read insights with minimal medical jargon, focused on the latest science for improving health and extending lifespan.
Each tip is an ~ 3-5 minute read or audio listen.
We hope you enjoy Longevity Tips and take a moment to drop us a line with a comment or question.
Weekly Insights for Lifelong Health
Health Tip #1: Whey vs. Casein Protein - 5.8.25
Optimizing Protein Intake: The Role of Whey and Casein
By Jonathan A. Jarman, MD
When evaluating optimal protein sources for muscle synthesis and recovery, two of the most effective options originate from a familiar source: milk. Both whey and casein proteins are classified as complete proteins, containing all nine essential amino acids required for human health. They are also highly bioavailable, making them exceptionally efficient for supporting muscle repair, hypertrophy, and overall recovery.
A widely accepted guideline for individuals engaged in resistance training or seeking to maintain lean muscle mass is the consumption of approximately 1 gram of protein per pound of body weight per day, if you are fit and under 25% body fat. An overweight individual (body fat >25%) should use this amount for lean body weight with resistance training. Supplementation with whey and casein can significantly facilitate meeting this target in a practical and sustainable manner.
1. Whey Protein: Fast-Acting and Branched-Chain Amino Acids (BCAA)-Rich
Whey protein is rapidly digested and absorbed, making it a preferred option immediately post-exercise when the goal is to initiate muscle protein synthesis. Of particular importance, whey is rich in leucine, Isoleucine and valine, branched-chain amino acids (BCAA) that serve as a key trigger for the anabolic (muscle building) signaling pathway known as mTOR. There is no need to add a BCAA supplement if using whey powder. Whey protein is the gold standard for stimulating muscle protein synthesis.
However, emerging evidence suggests that even distribution of protein intake—approximately every 6 to 8 hours—may be more important than the timing of a single post-workout dose. Thus, while whey remains a strong choice after resistance training, its broader value lies in supporting consistent protein availability throughout the day.
Our research, on our patients, shows that participants who follow this daily protein intake and do NOT focus on after resistance training protein drinks maintain high levels of amino acids in their blood continuously, which supports the emerging evidence of taking in protein every 6-8 hours vs the traditional post workout protein drink.
For individuals with lactose intolerance, whey isolate offers a viable alternative. This form is processed to remove the majority of lactose, resulting in a product that is easier to digest and typically well tolerated. It is important to ensure that the label specifically states "isolate" to obtain these benefits.
2. Casein Protein: Sustained Release and Overnight Support
In contrast to whey, casein protein is digested slowly, resulting in a prolonged release of amino acids into the bloodstream. This characteristic makes casein particularly well-suited for consumption prior to sleep, supporting overnight muscle recovery and reducing muscle protein breakdown.
Casein is also an effective option for midday supplementation, especially when longer-lasting satiety is desired. While it is comparatively lower in BCAAs than whey, its sustained release profile complements whey’s rapid absorption, making it an excellent addition to a comprehensive protein strategy.
Combining Whey and Casein: A Synergistic Approach
Both proteins may be consumed independently or combined to provide dual-phase amino acid delivery—fast and slow—which can be particularly beneficial in individuals aiming for optimal anabolic support across varied time intervals.
For practical guidance, I have created a simple, downloadable reference chart that outlines the differences between whey and casein, along with their ideal timing and use cases. This resource is available via the link below the chart.
Whey and casein powder supplements allow one to dial in the amount of each needed and when needed.
Boxed Protein Drinks vs Whey and Casein Concentrated Powders
Boxed protein drinks tend to be milk concentrates. Milk is 80% casein and 20% whey. Hence, boxed protein drinks have a similar ratio and are not a substitute for the best protein type for muscle hypertrophy - whey.
Use these boxed drinks for convenience and mid-day when you need to reduce hunger, but use concentrated whey powder for resistance training and muscle hypertrophy.
Health Tip #2: Longevity & Health Span - Essentials -5.12.25
The Real Keys to Longevity
By Jonathan A. Jarman, MD
In a recent interview, Dr. Mehmet Oz was asked to identify the most important factor contributing to health. His response: “Exercise.” While exercise is indeed a foundational element, it represents only one component of a broader, evidence-based approach to optimizing both health span and longevity.
Entire books are written on the subject of longevity; however, the principles outlined below represent the most current and evidence-based consensus. Epigenetic methylation is not included, as I believe the science surrounding its practical application remains insufficiently validated to warrant behavioral changes beyond those already supported by the principles presented here.
These fundamentals need to be combined with colonoscopy, coronary artery calcium scan, Pap smear, breast imaging, Galleri test, HPV test, bone scan, PSA and other tests when indicated.
1. Maximal Oxygen Uptake (VO₂ Max): The Primary Longevity Indicator
VO₂ max—defined as the maximum rate of oxygen consumption measured during incremental exercise—is widely regarded as the most powerful single predictor of overall health and lifespan. A high VO₂ max is indicative of efficient cardiovascular, pulmonary, and neuromuscular function. It correlates with:
- Strong cardiac performance
- Optimal pulmonary efficiency
- Enhanced cognitive function
- Reduced adiposity
- Coordinated organ system integration
Despite its significance, VO₂ max is rarely assessed in routine clinical practice. This metric should be measured and monitored regularly, particularly in preventive care settings.
2. Heart Rate Variability (HRV)
Heart rate variability (HRV) is strongly associated with mortality, especially in the context of cardiovascular and overall health.
- Cardiovascular mortality: Low HRV is a predictor of sudden cardiac death, heart failure progression, and post-myocardial infarction mortality.
- All-cause mortality: In both healthy and clinical populations, reduced HRV has been associated with shortened lifespan.
- Critical care settings: In ICU patients, low HRV is a marker of poor prognosis and is often used to track deterioration.
Heart Rate Variability (HRV) and VO₂max assess distinct yet complementary aspects of physiological health: HRV reflects autonomic nervous system balance and recovery capacity, while VO₂max measures the efficiency of the cardiovascular and respiratory systems during maximal exertion.
The most accurate devices to measure HRV have a chest strap to monitor the heart directly as an EKG does. The peripheral devices that offer HRV estimates are Oura, Apple Watch and Whoop to name a few. Direct cardiac HRV is done with a Morpheous, Polar H10, Garmin HRM-Pro / HRM-Pro Plus.
To get true resting HRV, you should:
- Use these devices first thing in the morning
- Sit or lie down in a relaxed state for 2.5–5 minutes
Both are independently associated with improved fitness, resilience, and longevity. While various factors influence each, Zone 2 aerobic training is one of the most effective shared interventions for improving both metrics—enhancing parasympathetic tone and mitochondrial function simultaneously.
3. Metabolic Health: A Four-Part Clinical Framework
Maintaining metabolic health significantly reduces the risk of chronic disease and early mortality. Four critical parameters define a healthy metabolic profile:
- Blood pressure below 120/80 mmHg
- Total body fat below 25%, with visceral fat less than 2.2 pounds
- Cholesterol levels optimized based on individual risk stratification
- Fasting blood glucose consistently under 100 mg/dL
Accurate assessment of adiposity—particularly visceral fat—requires a DEXA (Dual-Energy X-ray Absorptiometry) scan, which provides a far superior analysis compared to BMI. Unfortunately, DEXA scans remain underutilized in primary care.
4. Avoid Tobacco and Limit Alcohol Consumption
The evidence is unequivocal: the use of tobacco—whether smoked or smokeless—is a major contributor to multisystem disease, including various cancers. Complete avoidance is imperative.
Alcohol consumption should be strictly moderated. Recommendations include:
- No more than one standard drink per day
- Preferably limiting total weekly intake to just a few drinks
- Avoiding binge patterns (e.g., no drinks during the week then seven drinks consumed on a single weekend occasion)
- Abstaining from alcohol in the hours leading up to sleep, due to its adverse impact on sleep architecture
5. Muscular Strength, Movement, and Physical Resilience
Preserving musculoskeletal strength and functional mobility is essential to healthy aging. Interventions should include:
- Routine resistance training
- Daily stretching or mobility exercises
- Engagement in sports that promote coordination, reflexes, and balance
While cardiovascular conditioning is addressed through VO₂ max, muscular strength provides reserve capacity during illness and reduces injury risk. A 2018 study published in Mayo Clinic Proceedings listed several sports positively associated with increased lifespan. Though causality remains uncertain, sports such as tennis likely confer both physiological and psychological benefits due to their high-intensity intervals, cognitive demands, and inherent social interaction.
It is also notable that a 2008 Swedish study published in the Scandinavian Journal of Medicine & Science in Sports found that golfers live approximately five years longer than non-golfers. Although not included in the Mayo Clinic study, this finding underscores the potential benefit of socially engaging, physically active pastimes. The impact of newer sports such as pickleball remains to be fully studied.
6. Cognitive Engagement and Mental Stimulation
Sustained intellectual engagement contributes to neuroplasticity and may delay cognitive decline. Recommended activities include reading, writing, strategic gameplay, and the acquisition of new skills. Mental stimulation is a key pillar of healthy aging.
7. Social Connection
Social integration plays a profound role in mental, emotional, and physical well-being. Individuals with strong social ties exhibit lower rates of depression, dementia, and all-cause mortality. Isolation is a significant risk factor and should be actively mitigated through community involvement and regular interpersonal interaction. The long running Harvard Study of Adult Development, started in 1938, concluded in the 2023 book The Good Life: Lessons from the World’s Longest Scientific Study of Happiness, by Robert Waldinger, MD and Marc Schulz, PhD:
- The quality of close relationships (with partners, friends, and community) is more predictive of long-term health and happiness than wealth, IQ, or fame.
- Loneliness and poor social connections were as harmful as smoking or alcoholism in terms of long-term health impact.
- Strong relationships protect the brain and reduce the risk of memory decline.
8. Genetic Predisposition
While genetics contribute to individual health trajectories, they do not determine outcomes with certainty. Most chronic conditions associated with aging are significantly modifiable through behavioral and environmental interventions. Nevertheless, understanding one’s genetic risk can inform appropriate screening and early intervention.
9. Sleep Quality and Duration
Sleep is foundational to human health. A consistent duration of 7 to 8 hours per night is associated with improved immune function, hormonal balance, metabolic regulation, and cognitive performance. Chronic sleep deprivation has been linked to increased risk of cardiovascular disease, obesity, type 2 diabetes, and neurodegeneration.
10. Dermatologic Protection
Consistent use of a broad-spectrum sunscreen with SPF 30 or higher protects against approximately 97% of UVB radiation. This simple intervention significantly reduces the risk of skin cancer—the most commonly diagnosed cancer globally—and helps prevent premature aging of the skin.
Conclusion: A Unified Framework for Longevity
The 10 principles outlined above constitute a robust, evidence-based framework for extending both life span and health span.
While nutritional strategies, protein intake, and the use of supplements may further refine and personalize longevity interventions, they should be considered adjunctive to these foundational measures. Far too often, individuals pursue pharmacologic or supplemental solutions while neglecting the core behavioral determinants of long-term health.
A few targeted supplements may be helpful in achieving these goals, but indiscriminate supplementation offers limited value and often substantial cost without proven benefit. Similarly, medications for hypertension, dyslipidemia, or type 2 diabetes are appropriate when clinically indicated, but they do not substitute for metabolic health achieved through weight loss, physical activity, and dietary regulation.
Indeed, for many individuals, simply reducing total and visceral fat to optimal levels can normalize blood pressure, glucose, and lipid markers. Some studies suggest that reducing body fat to approximately 20% may yield additional benefits through reduced systemic inflammation.
Ultimately, medication should be viewed as a tool — not a replacement — for lifestyle interventions that address the underlying causes of metabolic dysfunction.
Longevity Pharmaceuticals: Current Evidence
At present, there are no pharmacologic agents conclusively proven to extend human lifespan.
While there is significant interest in various compounds, no drug can currently be recommended for longevity purposes based on robust human data.
The TAME study (Targeting Aging with Metformin) is an ongoing clinical trial designed to assess whether metformin, a medication widely used to manage type 2 diabetes, may have protective effects related to aging. Results from this study are anticipated to clarify metformin’s potential role in extending health span or delaying age-related diseases.
Rapamycin, an mTOR inhibitor, has demonstrated longevity benefits in animal models. However, these results have not yet been replicated or validated in human studies. At this stage, its use for life extension remains theoretical and unproven in clinical settings.
Although further developments are expected in the field of longevity pharmacology, no existing drug can be endorsed as a safe or effective agent for increasing human lifespan at this time.
Future Publications
A detailed analysis of nutrition, vitamins, and supplements as they relate to aging and longevity will be provided in an upcoming publication titled:
“Can We Live to 125?”
This article is scheduled for release in approximately one month and will explore both evidence-based strategies and emerging hypotheses in the field of extended lifespan.
Health Tip #3: Taurine: Its Impact on Longevity and Health
By Jonathan A. Jarman, MD
A pivotal study on taurine and its potential effects on longevity and healthspan was published in Science in 2023, one of the most prestigious scientific journals. The findings received widespread media attention due to the compelling result that taurine supplementation in middle-aged mice extended lifespan by approximately 12%.
Some commentators extrapolated these results to humans, suggesting a possible increase in lifespan of 7–8 years if taurine is supplemented. However, direct extrapolation from taurine models to humans is scientifically inappropriate. While taurine studies in mice are a common starting point due to their low cost and short lifespans, which allow for rapid data collection, they do not reliably predict outcomes in human populations.
Nevertheless, this study represents an exciting development in the field of longevity research. It underscores taurine’s potential, but extensive human research is still required to understand its implications for human lifespan.
More notably, the study also reported significant improvements in health span indicators in rhesus monkeys, including enhanced bone density, metabolic health, and immune function. Although lifespan was not assessed in the primate study, these findings carry more translational weight, given the biological similarities between rhesus monkeys and humans.
Taurine is a naturally occurring amino acid in humans that is synthesized primarily in the human liver from cysteine, and to a lesser extent in the brain, kidneys, and pancreas. As such, it is classified as a non-essential amino acid. Notably, taurine levels decline with age—a fact that can be verified through routine laboratory tests, as performed on participants in our Foundation’s research.
According to the Science study, taurine levels in healthy individuals decrease by approximately 80% between the ages of 5 and 60. Supplementation with 2–3 grams per day has been shown to be safe in clinical settings.
Further evidence supporting taurine’s broad health benefits has been published across several respected journals:
- A 2024 Stanford Medicine study reported a positive impact of taurine on body weight, though the findings would be more compelling if limited to body fat metrics rather than overall weight.
- A 2024 meta-analysis in Nutrients demonstrated improved glycemic control and insulin sensitivity in obese individuals treated with taurine.
- Nutrition & Diabetes (2024) reported reductions in blood pressure, fasting glucose, and triglyceride levels following taurine supplementation.
- Neural Regeneration Research identified taurine’s role in reducing neural apoptosis, suggesting potential in mitigating neurodegenerative disorders and depression.
- Nutrition (2024) reported that taurine supplementation may help prevent hypertension.
- An eight-year longitudinal study published in Frontiers in Nutrition (2024) observed increased muscle strength with taurine supplementation, particularly in individuals over the age of 65. This may explain its frequent inclusion in energy drinks and pre-workout formulations.
- Scientific Reports (2024) highlighted cognitive enhancements associated with taurine use.
Collectively, these studies suggest a broad and promising spectrum of health benefits associated with taurine supplementation.
However, it is critical to consider potential risks. A study published on May 14, 2025, in Nature, titled Taurine from Tumour Niche Drives Glycolysis to Promote Leukaemogenesis, reported that taurine may promote the growth of certain leukemia cell types. It is important to emphasize that this finding does not establish a causal link between taurine and cancer. Given that taurine is endogenously synthesized and essential for normal physiological function, its role in both healthy and pathological processes warrants nuanced interpretation.
It is plausible that, like many bioactive compounds, taurine may exert both beneficial and adverse effects depending on the context—supporting cellular function in healthy cells and potentially in malignant ones as well.
In conclusion, while the majority of commercial supplements offer minimal benefit and primarily profit manufacturers, taurine is supported by a growing body of data that justifies its use. Given its calming properties, a dosage of 2–3 grams taken at bedtime may be beneficial.
Please feel free to reach out with questions or comments.
Health Tip #4: Vitamins & Minerals–Do we need to take them?
By Jonathan A. Jarman, MD
Do You Need to Take Vitamins? The Answer: It Depends.
Approximately 1 in 3 Americans takes a multivitamin or multiple vitamin supplements daily.
According to the Centers for Disease Control and Prevention (CDC), the use of multiple dietary supplements increases with age. Among adults aged 60 and older, roughly 50% report taking more than one dietary supplement regularly.
In the United States, the vitamin and mineral retail market is projected to generate $3.06 billion in revenue by 2025. Globally, this market is estimated to reach $61.8 billion, underscoring the widespread reliance on supplementation.
Before addressing whether supplementation is necessary, it's helpful to understand the basic categories of vitamins.There are two primary types: water-soluble and fat-soluble vitamins.
This distinction is important because the body processes them differently.
- Water-soluble vitamins—which include vitamin C and the eight B vitamins—are not stored in significant amounts in the body. Excess quantities are typically excreted in the urine.
- Fat-soluble vitamins—vitamins A, D, E, and K—can accumulate in body tissues. Excessive intake may lead to toxicity, making these supplements riskier when consumed in high doses.
It’s also worth noting that the body can synthesize certain vitamins to a limited extent. These include vitamins D, K, B3 (niacin) and B7 (biotin).
While vitamin supplementation can be beneficial in some cases, it is not without risks. Whether or not one should take vitamins depends on diet, health condition and specific nutrient needs - all measurable via blood levels.
Summary Table of Vitamins the Body Can and Cannot Produce:
What Is the Evidence Supporting Vitamin Supplementation for Americans?
One of the most comprehensive studies on multivitamin use is the Physicians' Health Study II (PHS II), a large-scale, randomized, double-blind, placebo-controlled trial initiated in 1997 and concluded in 2011. Conducted by researchers at Brigham and Women’s Hospital and Harvard Medical School, the study involved 14,641 male physicians over the age of 50 who were administered a daily multivitamin (Centrum Silver) and followed for an average of 11.2 years.
While the PHS II is considered a well-designed and robust study, it has notable limitations. The study population was composed primarily of healthy, white, male physicians—a group that does not fully represent the diversity of the U.S. population. As a result, the generalizability of its findings to populations of different ages than the study cohort, women, individuals of other races or ethnicities and those with poor diets or chronic health conditions is limited.
Despite these constraints, the broader consensus remains: most Americans who consume a balanced diet are likely obtaining sufficient vitamins and minerals from food sources alone, and routine supplementation may offer little to no additional benefit. However, this does not mean that no one benefits from taking a multivitamin—individual needs and circumstances vary.
In 2022, the U.S. Preventive Services Task Force (USPSTF)—an independent, volunteer panel of national experts in disease prevention—published an Evidence Report analyzing 84 studies encompassing roughly 700,000 participants of both sexes. The task force found little to no evidence that vitamin and mineral supplements prevent early mortality, cancer, or cardiovascular disease—the leading causes of death in the United States. But the analysis only looked at disease prevention and not health optimization - an important distinction.
It is important to recognize the scope and perspective of the USPSTF. As a public health body, its recommendations are designed to inform care at the population level, often with a focus on cost-effectiveness. In short, they are not looking at the patient as an individual.
For instance, the same panel recommends against PSA (prostate-specific antigen) testing for prostate cancer screening in men over age 70. This guidance has been controversial; notably, President Biden’s prostate cancer was not diagnosed at an earlier stage because his physicians followed this recommendation.
In my view, such decisions—especially when it comes to individualized screening—are best made collaboratively by the patient and their physician, rather than being governed solely by national guidelines for groups with cost in mind.
What About Individuals with Inadequate Diets?
Data from the National Health and Nutrition Examination Survey (NHANES), conducted between 2003 and 2006 and reviewed by the CDC, indicate that although overall vitamin deficiency rates are relatively low in the U.S., certain demographic groups are disproportionately affected. These include individuals with limited access to nutritious food, certain racial and ethnic minorities, and people with specific health conditions.
In such cases, supplementation may be not only beneficial but necessary. Ultimately, the decision to take vitamin or mineral supplements should be informed by individual health status, dietary intake, and in some cases, medical testing—ideally under the guidance of a physician.
These deficient groups are:
Summary Table of Vitamin Deficiencies and Groups
Should You Take Vitamins? A Personalized Approach Beyond Population Guidelines
Thus far, the discussion has focused on population-level data regarding vitamin use. However, the decision to supplement should ultimately be individualized—based on the adequacy of one’s diet and, more precisely, one’s actual nutrient status as determined through laboratory testing.
Older Adults and Nutrient Deficiencies
Several studies suggest that older adults in the United States may particularly benefit from vitamin and mineral supplementation. This is due to age-related physiological changes that affect nutrient absorption, as well as dietary patterns that may lack essential micronutrients.
Common Nutrient Deficiencies in Older Adults
Data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2003 and 2006. reveal substantial micronutrient inadequacies among U.S. adults aged 60 and older:
- Vitamin D: 95% have intakes below the Estimated Average Requirement (EAR)
- Vitamin E: 84% fall below the EAR
- Vitamin A: 45% have inadequate intake
- Vitamin C: 46% fall below the EAR
- Zinc: 15% have insufficient intake
These deficiencies can negatively impact immune function, bone integrity and cognitive performance. However, it is important to note that NHANES data reflect dietary intake, not measured vitamin levels, which introduces limitations in interpreting the prevalence and severity of true deficiencies.
I think it is very important to know that most vitamin and mineral testing recommendations from government and public health agencies (like the USPSTF, CDC, and IOM/NASEM) are focused primarily on avoiding disease and toxicity, not health optimization.
Evidence from Supplementation Studies
A 2012 study published in The Journal of Nutrition, Health & Aging titled “Vitamin Status in Elderly People in Relation to the Use of Nutritional Supplements” examined adults aged 70 to 90 and found:
- The status of vitamins A, C, and E was generally adequate.
- However, 88% had inadequate levels of vitamins D, K, and B6.
- Up to 10% were deficient in B1, B2, B12, and folate.
- Regular use of supplements significantly improved vitamin status.
The prevalence of poor nutritional status or malnutrition risk in older adults (>65 years) has been estimated to range between 4% and 25%. While supplementation can be beneficial, excessive intake of nutrients like iron and zinc—especially among older men—may lead to toxicity, highlighting the need for guided, evidence-based use.
Cognitive Health and Supplementation
Emerging research has linked certain nutrients to cognitive preservation and healthy aging:
- One study found that daily multivitamin use may help slow age-related cognitive decline.
- Another reported that vitamin D supplementation may protect telomere length, a marker of biological aging.
Given these findings, supplementation may be warranted for older adults in specific contexts:
- Vitamin D: Often needed due to reduced cutaneous synthesis with age.
- Vitamin B12: Absorption decreases with age; deficiency is linked to cognitive impairment.
- Calcium: Essential for bone health; may be needed if dietary intake is low.
- Magnesium and Zinc: Commonly deficient and crucial for many physiological processes.
Testing: Don’t Guess—Assess
To make informed decisions about supplementation, measuring your vitamin and mineral levels is key. Testing through a CLIA-certified laboratory, such as LabCorp, using advanced methods like LC-MS/MS (liquid chromatography–mass spectrometry), provides the most accurate results.
Most Commonly Tested Vitamins and Minerals
Conclusion
While most healthy adults in the U.S. with a balanced diet do not need routine vitamin or mineral supplementation, this changes with age.
Older adults are more likely to experience deficiencies due to changes in physiology and diet. Supplementation, when guided by clinical testing and physician oversight, can help maintain optimal health and prevent complications associated with nutrient deficits.
If you are concerned about your nutritional status, do not guess—ask your primary care physician to order appropriate vitamin and mineral tests. Personalized data provides the most reliable foundation for any decision regarding supplementation.
Health Tip #5: What is Heart Rate Variability (HRV) and why is it important?
Heart Rate Variability (HRV) is simply the variation in time between consecutive heartbeats. Specifically, it is the R–R interval period on an electrocardiogram (EKG).
HRV reflects the integration of brain, body and environment to include inflammation, recovery status, emotional regulation and even early neurodegeneration. As such many factors of health effect HRV. These factors will be addressed in this Longevity Tip.
While it might seem intuitive to think that the heart beats with perfect regularity—say, once every second if your heart rate is 60 bpm—the reality is more nuanced. Your heart may beat at 1.1 seconds, then 0.9 seconds, then 1.2 seconds and so on, BUT averaging out to 60 beats per minute.
These subtle fluctuations are not random noise—they carry profound physiological meaning and importance.
This is a diagram of HRV on an EKG strip.
The high spikes in the QRS electrical activity on an EKG are called the R tips. The average interval measurement period between EACH R tip is the Heart Rate Variability (HRV), usually measured over about 2.5 minutes in the morning.
Why HRV Matters
Contrary to popular belief, a consistent, clockwork heartbeat is not a sign of good health. In fact, more variability between beats—within a healthy range—indicates a more adaptable and resilient autonomic nervous system .
HRV Physiology in Simple Terms
I will try to make this as basic as possible to avoid putting anyone to sleep! You can skip this section if the way HRV works in our body is not of interest to you and move onto Influences of HRV.
In its most basic sense, HRV is controlled by the autonomic nervous system (ANS)—a branch of the peripheral nervous system (PNS) responsible for regulating involuntary functions like heart rate, breathing, and digestion.
The autonomic nervous system (ANS) is named for its "autonomous" or "self-governing" function — it operates largely unconsciously and automatically, without requiring voluntary control such as the higher central nervous system brain frontal lobes.
The term comes from:
- "Auto-" = self
- "Nomic" = governing (from the Greek nomos, meaning law or rule)
So the ANS governs bodily functions on its own — things like:
- Heart rate
- Blood pressure
- Respiration
- Digestion
- Pupil dilation/constriction
- Thermoregulation
- Sexual arousal
Even though it's unconscious, the ANS is tightly regulated by brain regions such as the hypothalamus, brainstem, and limbic system, and it can be indirectly influenced by your thoughts, emotions, and behavior (e.g., through breathwork or biofeedback training).
The ANS is composed of two main branches:
- Sympathetic Nervous System (SNS)
Classically called the “Fight or flight” part of the autonomic nervous system. The Sympathetic nervous system speeds up heart rate; primes body for action such as running from an animal that wants to eat you or getting into a fight on the playground. The SNS originates from the thoracic and lumbar spine. - Parasympathetic Nervous System (PNS)
Classically called the “Rest and digest” component of the ANS → Slows downheart rate; restores and conserves energy
Primarily mediated by the vagus nerve (cranial nerve X), which innervates the heart, lungs, GI tract, and more
These two systems constantly interact in a push-pull/yin yang dynamic.
For example:
When you inhale → vagal tone is inhibited by the SNS → HR increases slightly
When you exhale → vagal tone resumes → HR decreases slightly
This pattern is known as respiratory sinus arrhythmia, and it contributes directly to HRV.
Think of HRV as a real-time signal of your body's readiness:
- Athletes use HRV to guide training intensity.
- Doctors monitor HRV in ICU patients as a predictor of survival.
- Psychologists are exploring HRV biofeedback for anxiety and PTSD.
- Everyday users, like you and me, track HRV for insights into stress, sleep, and recovery.
In the early 2000s, HRV became measurable with wearables (e.g., Morpheus, Polar H10, Oura, WHOOP, Apple Watch, Elite HRV to name a few).
The most accurate wearables are those that use chest straps to directly measure your heart beats vs those that use a pulse to the skin on your wrist or finger.
I personally use the Morpheus Training System and Polar H10. The Morpheus for HRV guided cardio training/recovery and the Polar H10 to measure my HRV specifically in root mean square of successive differences (RMSSD). The Morpheus HRV combines a few parameters to provide their proprietary version of HRV and is NOT directly comparable to other system’s scores.
Hence, use the Morpheus for HRV guided recovery and training and not for an exact HRV score.
Influences of HRV
HRV is not a standalone measure of health, but it reflects key aspects of physiological status such as:
- Autonomic Nervous System Balance
- High HRV generally reflects a healthy dynamic between the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) branches of the autonomic nervous system (ANS).
- Low HRV may indicate sympathetic dominance, often seen with chronic stress, sleep disruption, overtraining, or illness.
2.Metabolic Health
- Obesity and insulin resistance lower vagal input and reduce HRV
3.Inflammation
- increased hsCRP and Il- 6, which we measure on all donors educes vagal tone and lowers HRV
- Physical Fitness and Cardiovascular Conditioning
- Athletes and physically fit individuals typically have higher resting HRV.
- As cardiovascular fitness improves, baseline HRV usually increases, reflecting enhanced parasympathetic tone and recovery capacity.
- Recovery and Readiness
- HRV is widely used in sports science to track recovery status and optimize training loads. I use it to plan my weekly cardio training routine.
- A drop in HRV can signal incomplete recovery, guiding athletes to adjust intensity or focus on rest.
- Stress and Sleep Quality
- Chronic psychological stress, emotional strain, and poor sleep all tend to suppress HRV.
- A consistently high HRV implies robust parasympathetic engagement and better coping capacity under stress.
- Alcohol (ETOH)
- Intake the night before measuring your HRV can reduce the score to less desirable.
- Ingestion the night before HRV morning measurement lowers HRV by boosting sympathetic activation, sleep disruption and inflammation.
- Drinking closer to 3-4 hours before sleep or increasing the dose of ETOH increases its negative effect on HRV.
- I encourage all who drink to measure their HRV in the morning after an evening of ETOH use, even if just a single drink.
- Resilience and System Flexibility
- HRV reflects how well your body adapts to internal and external stressors. It is a real-time biomarker of physiological resilience.
- Higher HRV is associated with greater adaptability and a healthier, more flexible nervous system.
- Long-Term Health Outcomes
- Low HRV is linked to increased risk of:
- Cardiovascular disease
- Type 2 diabetes
- Depression and anxiety
- All-cause mortality, especially post-myocardial infarction
- High HRV correlates with better cardiovascular health, emotional regulation, and longevity.
- Early Warning System
- Sudden drops in HRV can indicate:
- Overtraining
- Illness onset
- Poor sleep or excessive stress
- Lifestyle imbalances.
- Age
Age has a significant and well-documented impact on Heart Rate Variability (HRV): it tends to decrease with advancing age.
How Age Affects HRV
- General Trend
- HRV declines with agein both men and women.
- The parasympathetic branch (vagal tone)diminishes over time, while sympathetic activity often remains steady or becomes relatively more dominant.
- Early Adulthood to Middle Age
- In your 20s and 30s: HRV is generally at its highest.
- In your 40s–50s: There is a gradual decline, especially in high-frequency (HF) components that reflect parasympathetic activity.
- Older Adults (60s and beyond)
- HRV continues to decline more noticeably, with both time-domain and frequency-domain measures showing lower values.
- The autonomic nervous system becomes less flexible, reducing the body's ability to rapidly respond to stress or recover from exertion.
- Younger individualstypically have greater autonomic flexibility, enabling faster recovery and stronger stress resilience.
Aging-related decline in HRV has been associated with:
- Reduced baroreflex sensitivity
- Decreased vagal tone
- Slower recovery from stressors
- Increased risk of chronic disease
HRV Is Modifiable!
While aging affects HRV, it is not entirely fixed:
- Regular exercise (especially cardio aerobic and endurance)
- Good sleep hygiene
- Stress management (e.g., mindfulness, breathwork)
- Reduction of Metabolic Disease, e.g. obesity
- Minimized alcohol and stimulants
...can all help maintain or even improve HRV well into older age.
HRV by Age
Scientific Foundations
Awareness of HRV began in the early 20th century, but the landmark 1996 Task Force Report by the European Society of Cardiology and the North American Society of Pacing and Electrophysiology established formal standards for:
- HRV measurement (time-domain, frequency-domain, nonlinear methods)
- Physiological interpretation
- Clinical applications
This paper remains one of the most frequently cited references in HRV research.
In summary:
The fundamentals of HRV and why it is important.
- Indicator of Nervous System Balance
- High HRV → Strong parasympathetic activity (“rest and digest”), better adaptability.
- Low HRV → Sympathetic dominance (“fight or flight”), often linked to stress, fatigue, or illness.
- Stress and Recovery Monitor
- Tracks how well your body recovers from physical, emotional, or psychological stress.
- Helpful in guiding training intensity, workload, and rest days.
- Marker of Resilience and Adaptability
- Higher HRV is linked to greater physiological flexibility, meaning you can respond more effectively to challenges (physical or mental).
- Health and Longevity Correlations
- Low HRV is associated with increased risk of:
- Cardiovascular disease
- Diabetes
- Depression
- All-cause mortality (especially post-heart attack)
- High HRV is generally a sign of better cardiovascular health, fitness, and emotional regulation.
- Tool for Early Warning
- Sudden drops in HRV may signal:
- Overtraining
- Illness onset
- Poor sleep or high stress
- Imbalanced lifestyle choices
In a nutshell, HRV is a powerful biomarker of autonomic function, resilience, and overall system flexibility. Monitoring it can provide early insight into your physical and mental health, enabling proactive lifestyle adjustments for performance, longevity, and well-being.
Longevity Tip #6: Why Wearables Are Not the Answer for Fat Loss or Calorie Tracking
Why Wearables Are Not the Answer for Fat Loss or Calorie Tracking
By Jonathan A. Jarman, MD
(~ 4 minute read)
(~ 6 minute audio )
Exercise and diet are both fundamental parts of the health equation, but they play different roles. Diet is the primary driver of fat loss because it directly controls energy intake, while exercise supports health by improving metabolic fitness, preserving lean muscle, and boosting cardiovascular function. Yet, confusion often arises around how exercise fits into fat loss—and nothing has added more to this confusion than the devices on our wrists and gym equipment dashboards that spit out “calories burned.”
It seems simple enough. If our body fat is primarily driven by the calories we consume minus the calories we use in a day, then the formula is:
Calories Consumed in 24 hours – Calories Burned in 24 hours = Net Calories
So shouldn’t it be easy? Just eat fewer calories than you burn and the fat melts away, right? Yes—sort of. But not if you’re relying on what your Apple Watch, treadmill, or elliptical machine says about how many calories you’ve “torched.”
Here’s why. Imagine Bill, who eats 2000 calories per day as part of his Foundation’s health and fat-loss plan. His watch congratulates him: “Way to go, Bill! You just burned 500 calories in your squash match!” Bill now thinks he’s only at 1500 net calories for the day. That leads to two possible mistakes:
- He eats 500 extra calories as a reward because the watch told him he earned it.
- He doesn’t eat more, but he walks around thinking he’s created a huge deficit when in reality, the device’s estimate may be way off.
This is the trap: we take inaccurate calorie burn numbers as truth, and it shapes our choices in ways that sabotage our goals.
The Problem With Calorie Estimates
Research has consistently shown that wearable calorie estimates are unreliable. A 2017 Stanford study on seven popular devices found that while heart rate measurements were fairly accurate (average error ~5%), calorie burn estimates were off by an average of 27%, and sometimes by as much as 93% (Shcherbina et al., 2017).
Fast forward to a 2025 University of Mississippi study on the Apple Watch Series 9: the device’s average error for calorie burn was 27.96%, across walking, running, cycling, and mixed workouts (University of Mississippi, 2025).
And it’s not just Apple. A 2024 umbrella review confirmed that across multiple brands, calorie burn estimates often deviated by ±20% or more—making them far from precise tools (Ding et al., 2024).
Why Devices Get It Wrong
Wearables rely on accelerometers, optical heart rate sensors, and algorithms. But calorie burn depends on far more than wrist motion and heart rate. Age, sex, body composition, metabolic efficiency, and even skin tone can alter results.
For example:
- Resistance training and cycling often produce huge errors because there’s little wrist movement.
- Skin pigmentation or tattoos can interfere with optical sensors, reducing accuracy (O’Driscoll et al., 2024).
In short: the watch doesn’t know you—your metabolism, your efficiency, your unique biology. It just guesses.
The Real Fat Loss Equation
At the end of the day, fat loss comes from a consistent calorie deficit. But you don’t need precise burn numbers from a device to achieve this. In fact, relying on those numbers can backfire:
- People overestimate exercise calories, then eat more (“I earned dessert”).
- Devices ignore non-exercise activity (walking, chores, fidgeting), which often contributes more to daily burn than a single workout.
- Chasing false precision distracts from building sustainable habits.
Think of it this way: diet controls intake and directly drives fat loss, while exercise supports the process by improving health, strength, and performance. They complement each other, but they’re not interchangeable.
Smarter Alternatives
If calorie burn estimates are so flawed, what should you focus on instead?
- Use wearables for heart rate, HRV and step tracking, where they’re far more reliable.
- Watch trends in body weight over weeks, not day-to-day fluctuations.
- Measure waist circumference, strength gains, or progress photos as signs of change.
- Pay attention to nutrition tracking, since intake is easier to measure than expenditure.
The Takeaway
Wearables are fantastic for motivation, accountability, and activity reminders. But when it comes to fat loss, they’re not trustworthy calorie accountants. Science shows they routinely miss the mark—sometimes by 20–40%, sometimes by much more. Instead of chasing misleading numbers, focus on the fundamentals: eat well, move consistently, train with purpose, and track progress with tools that matter.
References
- Shcherbina, A. et al. (2017). Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort. Journal of Personalized Medicine. Stanford Medicine
- University of Mississippi (2025). Apple Watch accuracy study. Ole Miss News
- Ding, D. et al. (2024). Accuracy of wearable devices in estimating energy expenditure: umbrella review. Sports Medicine. Springer
- O’Driscoll, R. et al. (2024). Variations in accuracy of Apple Watch energy expenditure estimates by skin pigmentation. Sports, 12(4), 275. MDPI
Longevity Tip #7: Can Better Cardio Help Us Make Muscle? - 10.10.25
Longevity Tip 7
Can Better Cardio Help Us Make Muscle?
By Jonathan A. Jarman MD
(~3 min read)
(~4 min audio)
No way, right? Runners are skinny, have low bone density and are not strong. Right? True. Runners are prone to injury due to lack of bone density and strength. Right? True.
Trying to get a runner to do resistance training is like asking someone who only runs marathons to try a pull-up. Can’t happen.
So then if all this is true – and it is – how can cardio training, and a better VO₂Max that comes with it, help build muscle?
As my cardio and measured VO₂Max improved from playing tennis 5–7 times a week and completing my Morpheus weekly cardio goals, I noticed I was less fatigued between resistance training sets. I did research to see if what I noticed had a body of scientific evidence.
It does.
This blog is written with those of you in mind who hate cardio but love resistance training. If you want optimum health, you have to be focused on both.
Cardio training is essential for VO₂Max and numerous studies confirm VO₂Max is the single most important metric for longevity. Yet VO₂Max is not related to a strong body. (1,2,3,4,5)
First, know that resistance training does NOT contribute to cardio Zone training. I have found a lot of confusion with resistance training HR and Cardio Zones. Even if you are in Zone 2 during resistance training, it does NOT contribute to your weekly cardio zone training needs. No need to think about your heart rate while pumping iron.
And yet the opposite is true and that’s the gist of this blog. Improved VO₂Max (cardiorespiratory fitness) does improve resistance-training sets without loss of performance.
For those of you who don’t enjoy cardio training, this is how it will benefit your resistance training gains. It will make your muscle building workouts more efficient.
As your VO₂Max improves, your needed rest time between sets will reduce.
We have to rest between resistance sets because we use up stored muscle energy (ATP and phosphocreatine (PCr)) during lifting and have to allow the body to replace these molecules during rest.
After depletion from lifting, PCr resynthesis requires oxygen and mitochondrial activity, taking roughly 2–5 minutes to restore fully. Also, moderate- to high-rep sets accumulate lactate and H⁺ ions, lowering muscle pH. As you know, I am not a fan of high-rep sets for building power. Low-rep sets at higher weight build power.
Rest allows time for lactate clearance and buffering, so contractile performance recovers.
Shorter rest means incomplete PCr recovery → lower force and power output in the next set. This IS important. You need full recovery to recruit your muscle building forces to maximally build muscle and power.
There is also central (brain) and peripheral nerve issues with lifting as heavy lifting involves high motor unit recruitment and central nervous system drive.
Rest periods let the nervous system re-prime for maximal output — especially important for compound lifts or near-maximal loads. Note that older lifters benefit from slightly longer rest for neural recovery — but improved aerobic capacity can offset some of that.
Optimal rest varies based on goals. (6)
This is the crux for how cardio fitness helps resistance training fitness. Higher VO₂max → faster PCr and lactate recovery plus ATP replenishment → you can trim rest intervals by 20–50% while keeping output stable.(7)
So, if you improve your cardio, you will rest less between sets and get MORE done in the same amount of time. You will accumulate greater total training volume per session.
In summary, increasing VO₂max improves cardiovascular and metabolic recovery between sets, enabling shorter rest without fatigue buildup. This enhances training efficiency and total work output — one of the reasons elite athletes across sports (including power and team sports) prioritize aerobic capacity alongside strength.
VO₂max builds your engine. Strength builds your chassis. You want both if your goal is performance and longevity.
References
- Kodama S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events: a meta-analysis. JAMA 2009. (1-MET ≈ 13% lower all-cause mortality). JAMA Network
- Mandsager K., et al. Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing. JAMA Netw Open 2018. (122,007 patients; elite vs low HR 0.20). JAMA Network
- Ross R., et al. Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign. AHA Scientific Statement, Circulation 2016. PubMed
- Lang JJ., et al. Cardiorespiratory fitness is a strong and consistent predictor of risk across many mortality outcomes — overview 2024. (Systematic-review-of-reviews). PMC
- Milanović Z., et al. Endurance vs HIIT for VO₂max — systematic review & meta-analysis. 2015 (and subsequent HIIT meta-analyses) — show VO₂max is trainable; HIIT often superior or similar. PubMed+1
- . Bogdanis, G. C., Nevill, M. E., Boobis, L. H., Lakomy, H. K. A., & Nevill, A. M. (1996). Recovery of power output and muscle metabolites following 30 s of maximal sprint cycling in man. Journal of Applied Physiology, 80(3), 876–884. https://doi.org/10.1152/jappl.1996.80.3.876
- Tomlin, D. L., & Wenger, H. A. (2001). The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Medicine, 31(1), 1–11. https://doi.org/10.2165/00007256-200131010-00001
Health Tip #8: How to evaluate health care advice in the media and internet.
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Health Tip #9: Cognitive improvement with supplements - can jelly fish make us smarter?
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