Studies
Investigating the accuracy of Apple Watch VO2 max measurements: A validation study
In a study of 30 participants, Apple Watch VO₂ max estimates were on average 6 mL/kg/min lower than values measured with the gold-standard treadmill test. The results varied widely between individuals, sometimes underestimating or overestimating VO₂ max by a large margin. Overall, the watch showed a mean error of 13%, indicating that it may not provide a precise measurement for clinical or performance purposes.
Survival of the fittest: VO2 max, a key predictor of longevity?
The paper emphasizes that while exercise cannot extend genetically predetermined lifespan, it effectively adds quality and healthy years by enhancing fitness and preventing frailty. It also discusses the importance of assessing cardiorespiratory fitness in clinical practice as a vital sign and supports tailored exercise interventions to promote survival and life quality in both healthy individuals and patients with chronic diseases like COPD, heart failure, and cancer.
Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis
The 2009 JAMA meta-analysis on cardiorespiratory fitness (CRF) highlights the powerful link between VO2 max—a key measure of CRF—and long-term health outcomes. VO2 max represents the maximal aerobic capacity, measured in metabolic equivalents (METs), reflecting how efficiently the body uses oxygen during exercise. The study shows that individuals with higher VO2 max values have significantly lower risks of all-cause mortality and cardiovascular disease (CVD) events. Specifically, people with a VO2 max of 7.9 METs or higher had a substantially reduced risk of death and heart-related problems compared to those below this threshold. Every 1-MET increase in VO2 max corresponded to a 13-15% lower risk of death or CVD events. This research solidifies VO2 max as a critical, modifiable predictor of longevity and cardiovascular health, emphasizing the importance of maintaining and improving aerobic fitness to reduce health risks.
Association between basal metabolic rate and cognitive function in Chinese older adults: the mediating effect of sarcopenia
A recent large study of adults over 60 found that a higher basal metabolic rate was linked with better cognitive performance — and that muscle loss accounted for nearly 30% of that relationship. How your body burns energy at rest and how much muscle you maintain may influence your brain’s sharpness as you age.
Current Resting Metabolic Rate Prediction Equations Lack Sensitivity and Specificity to Indicate Relative Energy Deficiency in Sport
A 2025 study on more than 180 elite athletes found that the standard equations used to “predict” resting metabolic rate (RMR) are wildly unreliable—missing a large share of athletes who were actually experiencing metabolic suppression and low energy availability. In fact, depending on the equation used, the number of athletes flagged as having a low RMR ranged anywhere from 1% to 68%, despite nearly half being at real risk. The takeaway is simple: if you want to understand your true metabolic status, you can’t rely on generic formulas. Direct measurement through high-quality RMR testing is the only accurate way to assess how your body is functioning at rest.
Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study
This study suggests that measurement of grip strength is a simple, inexpensive risk-stratifying method for all-cause death, cardiovascular death, and cardiovascular disease. Further research is needed to identify determinants of muscular strength and to test whether improvement in strength reduces mortality and cardiovascular disease.
Longitudinal association between handgrip strength, gait speed and risk of serious falls in a community-dwelling older population
In a large 4-year follow-up of over 16,000 healthy older adults, reduced hand-grip strength was linked with a significantly higher risk of serious falls requiring hospitalisation—each standard-deviation drop in grip strength raised the risk by about 27%. The link was strongest in men of all body-weights and in obese women.
Low skeletal muscle mass index and all-cause mortality risk in adults: A systematic review and meta-analysis of prospective cohort studies
Low SMI was significantly associated with the increased risk of all-cause mortality, and the risk of all-cause mortality associated with low SMI was higher in adults with a higher BMI. Low SMI Prevention and treatment might be significant for reducing mortality risk and promoting healthy longevity.
Muscle mass index as a predictor of longevity in older adults
The study concluded that older adults with greater muscle mass relative to their height had significantly lower mortality rates than those with less muscle. It demonstrated that muscle mass, independent of fat and traditional risk factors, is a strong predictor of longevity, highlighting that clinicians should focus on maintaining muscle rather than body weight alone when evaluating health in older adults
Skeletal Muscle Mass as a Mortality Predictor among Nonagenarians and Centenarians: A Prospective Cohort Study
A large prospective cohort study of more than 700 adults aged 90 years and older found that skeletal muscle mass remains a powerful predictor of survival, even in extreme old age. Over a 4-year follow-up, participants with lower muscle mass had a significantly higher risk of death, particularly among women, independent of age and functional status.
Abdominal obesity and mortality: The Pennington Center Longitudinal Study
This study investigated the relationship between visceral adipose tissue (VAT) measured by CT scans and all-cause mortality in white adults. It found a significant positive association, meaning higher amounts of VAT were linked to increased risk of death from any cause. The study emphasizes the clinical importance of assessing VAT in obesity evaluation and related health risks. However, limitations include a small and non-representative sample and lack of comprehensive dietary data. The authors recommend further research with larger, diverse populations to confirm these findings and support VAT assessment as a priority in clinical obesity care.
A Meta-Analysis of Trabecular Bone Score in Fracture Risk Prediction and Its Relationship to FRAX
The objective of this meta-analysis was to determine whether TBS predicted fracture risk independently of FRAX probability and to examine their combined performance by adjusting the FRAX probability for TBS. The study concluded TBS is a significant predictor of fracture risk independently of FRAX. The findings support the use of TBS as a potential adjustment for FRAX probability, though the impact of the adjustment remains to be determined in the context of clinical assessment guidelines.
Global burden of injury due to low bone mineral density in adults aged 55 years and older, 1990 to 2021: A population-based study
From 1990 to 2021, global mortality from injuries due to low BMD increased by 8.2%, rising from 24.98 to 27.04 per 100,000 people among adults aged 55 and older. These injuries significantly impair physical function and contribute to decreased quality of life.
Meta-analysis: excess mortality after hip fracture among older women and men
This study looked at older adults who broke a hip and found that their risk of dying is much higher compared to people of the same age without a hip fracture. In the first three months after the break, their risk of death is about 6 to 8 times higher. Even years after the fracture, the risk remains above normal. Men have a higher risk of dying after a hip fracture than women do at the same age. This means a hip fracture is not just a bone injury but a serious health event that affects overall survival long-term. The study highlights how important it is to take special care of older people who have had a hip fracture to help improve their chances of living longer.