Longevity research has identified a handful of factors that consistently predict how long — and how well — people live. Some are things you do daily. Others are measurable markers of how your body is actually functioning right now, independent of the number on your birth certificate. This guide covers what the research actually supports, not trends or hype.

VO2 max — how efficiently your body uses oxygen during exercise — is one of the strongest predictors of all-cause mortality identified in large population studies. People in the lowest fitness categories have dramatically higher mortality risk than those even in the next category up, independent of other risk factors. Improving it: consistent cardiovascular training, particularly a mix of steady-state and higher-intensity intervals, over months and years — not a single workout.

Grip strength specifically has been studied at massive scale and found to predict cardiovascular and all-cause mortality — in some research, more strongly than blood pressure. It's believed to reflect overall muscular strength and physiological reserve, not just hand function. Broader strength — especially leg strength and the ability to rise from the floor unassisted — is independently linked to longevity, particularly as people age. Improving it: resistance training 2+ times per week, maintained consistently over years, is the most well-supported approach.

The ability to balance on one leg for 10 seconds and the ability to get up from the floor without using your hands (the sit-to-rise test) are both independently associated with mortality risk in adults, particularly past midlife. These aren't just tests of coordination — they reflect strength, flexibility, and neuromuscular function working together. Improving it: regular strength training, mobility work, and simply practicing these movements are all effective.

Waist-to-height ratio is a better predictor of metabolic and cardiovascular risk than BMI, because it specifically reflects visceral fat — the fat around your organs, which is more metabolically harmful than fat elsewhere on the body. See your Body Metrics tool for your current waist-to-height ratio.

Stable blood sugar, healthy blood pressure, and healthy cholesterol markers are all independently linked to reduced risk of the diseases that most commonly shorten life — cardiovascular disease and type 2 diabetes chief among them. See your Glucose Optimizer and Biomarkers Guide for more on tracking these.

Consistently short sleep (under 6-7 hours) is linked to increased risk of cardiovascular disease, metabolic dysfunction, and all-cause mortality. Sleep isn't passive recovery — it's when much of the body's repair and regulation happens. See the Training Safety guide for more on sleep and recovery.

Loss of muscle mass with age (sarcopenia) is linked to frailty, falls, and reduced independence later in life. Adequate protein intake combined with resistance training is the most well-supported way to preserve muscle mass as you age — which is the entire premise this app is built around.

Cognitive decline — particularly processing speed and executive function — is independently linked to mortality risk, not just quality of life. Cognitive trajectory is increasingly used as a genuine predictor of broader health decline, often showing up before physical decline does. Reaction time, working memory, and attention are all measurable, trainable-adjacent markers of cognitive function. Unlike physical fitness, cognitive decline is less directly reversible through simple "training" — but tracking it over time gives you real signal, the same way tracking strength or VO2 max does. See your Longevity Tests for reaction time tracking, one practical entry point into this.

Longevity is a heavily marketed space, and not everything promoted as "anti-aging" has strong evidence behind it in humans. Concepts like "biological age" tests, many supplements marketed for longevity, and some trending protocols have limited or preliminary human evidence compared to the fundamentals above: fitness, strength, body composition, metabolic health, sleep, and muscle mass. Be skeptical of any claim that promises a precise "age reversal" number — the strongest, most consistently supported levers are the unglamorous ones listed above.

• VO2 max and all-cause mortality: Mandsager et al., "Association of Cardiorespiratory Fitness With Long-Term Mortality Among Adults Undergoing Exercise Treadmill Testing," JAMA Network Open, 2018. • Grip strength and mortality: Leong et al., "Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study," The Lancet, 2015. • Sit-to-rise test and mortality: Brito et al., "Ability to sit and rise from the floor as a predictor of all-cause mortality," European Journal of Preventive Cardiology, 2014. • Balance and mortality: Araujo et al., "Successful 10-Second One-Legged Stance Performance Predicts Survival in Middle-Aged and Older Individuals," British Journal of Sports Medicine, 2022. • Push-up capacity and cardiovascular risk: Yang et al., "Association Between Push-up Exercise Capacity and Future Cardiovascular Events Among Active Adult Men," JAMA Network Open, 2019. • Waist-to-height ratio vs BMI: Ashwell & Gibson, "Waist-to-height ratio as an indicator of 'early health risk': simpler and more predictive than using a 'matrix' based on BMI and waist circumference," BMJ Open, 2016. • Sleep duration and mortality risk: Cappuccio et al., "Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies," Sleep, 2010. • Muscle mass, protein intake, and sarcopenia: Morley et al., "Sarcopenia With Limited Mobility: An International Consensus," Journal of the American Medical Directors Association, 2011. • Cognitive decline and mortality: Bassuk et al., "Cognitive impairment and mortality in the community-dwelling elderly," American Journal of Epidemiology, 2000. This is a summary of established research for general education. It is not a complete or exhaustive citation of the field.