Protocols by Charles Sieg

Testing

Body, fitness, and imaging tests

DEXA scans, VO2 max testing with spirometry, strength and blood pressure checks, sleep and hearing tests, and whole-body MRI: what each one measures, how precise it is, and what the results predict.

Overall evidence Mixed50 sourcesReviewed November 5, 2026

Fitness, bone density, lung function, grip strength, and blood pressure rest on large cohorts, trials, or guidelines, while whole-body MRI, wearable VO2 max estimates, and DEXA visceral fat have little or no outcome evidence behind them.

The short version

  • A test earns a place here when its result predicts something that matters. Fitness is the clearest case: in 122,007 adults who had treadmill tests, elite fitness carried an adjusted mortality hazard ratio of 0.20 compared with low fitness, an observational result like most on this page1.
  • DEXA is the standard bone density test and a solid way to track lean and fat mass, but a change between scans has to beat the machine's precision error, and its visceral fat number is loose for one person2,3.
  • Low lung function, weak grip, and a poor sit-to-rise score all go with higher mortality4,5,6, and the 2025 blood pressure guideline recommends monitoring at home7.
  • Whole-body MRI is the weakest case: the American College of Radiology says the evidence doesn't justify it for people with no symptoms, risk factors, or family history8.
  • Prices and guideline positions are as of November 2026, and where I couldn't source a price, none is given. Blood tests are on Lab tests worth knowing.

How I use it

I asked for DEXA scans for body composition and VO2 max testing with spirometry to be covered next to the blood tests. For context, I train, I follow keto, I take Nuvigil and retatrutide, and I do a 3-day water-and-broth fast once a month. None of my own results are on this page yet.

DEXA: body composition and bone density

What it measures. Dual-energy X-ray absorptiometry (DEXA, or DXA) measures bone density at the spine and hip, and a whole-body scan reports fat mass, lean mass, and percent fat2; consumer scans add fat by region and a visceral fat estimate9.

How precise. The International Society for Clinical Densitometry (ISCD) sets a technologist's minimum precision at 3% for total fat mass and 2% for lean mass and percent fat, and tells each facility to measure its own precision rather than use the manufacturer's figure2. For bone, the minimums of 1.9% at the lumbar spine, 1.8% at the total hip, and 2.5% at the femoral neck put the least significant change at 5.3%, 5.0%, and 6.9%2. A methodology review for athletes proposes a standard protocol (rested, overnight-fasted, minimal clothing, consistent positioning, and a check of the software's automatic segmentation) so repeat scans can be compared10.

Visceral fat is the loosest number. In 124 adults, DEXA tracked CT across the group (r² 0.957), but the 95% limits of agreement ran from −355 to +468 cm³ around a bias of +56 cm³3. Fine for groups, loose for one person.

Versus bioimpedance. Across 3,655 paired measures, bioimpedance matched DEXA within 1 kg at a BMI of 16 to 18.5, but from 18.5 up to 40 it overestimated fat-free mass by 3.38 to 8.28 kg and underestimated fat mass by 2.51 to 5.67 kg11. In 2,134 patients with obesity, the best equation put fat-free mass within 10% of DEXA in 75.7% of class I and II patients12. Neither study looked at lean athletes.

What it predicts. Each standard deviation of lower bone density raised fracture risk 1.5-fold (95% CI 1.4 to 1.6), and 2.3-fold for spine fractures measured at the spine and 2.6-fold for hip fractures measured at the hip, in pooled prospective cohorts13. The US Preventive Services Task Force (USPSTF) recommends screening women 65 and older and postmenopausal women under 65 at increased risk (grade B), and finds the evidence insufficient for men14. For muscle, the European sarcopenia consensus advises DEXA to confirm low muscle mass, with appendicular muscle mass cutoffs of 7.0 kg/m² for men and 5.5 kg/m² for women15. ISCD calls the effect on outcomes uncertain even for body composition indications such as large planned weight loss2, and I found no verified outcome number for DEXA body fat or visceral fat.

Radiation, cost, and where. A bone density scan delivers about 0.001 mSv, roughly 3 hours of natural background radiation; the average American gets about 3 mSv a year16. The patient page says not to take calcium supplements for at least 24 hours beforehand17, and pregnancy rules out a body composition scan2. Doctors order bone density tests, and ISCD's list of who qualifies starts with women 65 and older and men 70 and older2. Without a referral, BodySpec lists 100-plus US locations and says it cut the price of a scan from $300 to as low as $39, and DexaFit lists independently owned locations in 41 states; those are the sellers' own claims9,18.

VO2 max: cardiopulmonary exercise testing

What it measures. An accurate VO2 max test measures gas exchange by indirect calorimetry during an exercise test to exhaustion, usually in a lab with a gas analyzer and trained technicians19. In clinics it is cardiopulmonary exercise testing (CPET), which assesses the lungs, heart and circulation, and muscles working together20. Results often come in metabolic equivalents (METs); one MET more is roughly 1 kilometer per hour faster running21.

Where spirometry fits. Spirometry (below) is a separate test of how much air a person can blow out and how fast. Its ATS and ERS standard also covers FEV1 measured during exercise testing, says to avoid vigorous exercise in the hour before spirometry, and cites a study in which 10% of patients having maximal CPET had simple, self-limited arrhythmias brought on by spirometry22. I found no source on how consumer labs combine the two.

How precise. I have no sourced test-retest figure for a lab test. Wearables are the weak link: in a meta-analysis of fourteen validation studies, devices estimating VO2 max from resting data overestimated it by 2.17 mL/kg/min on average (limits of agreement −13.07 to 17.41), while exercise-based estimates averaged −0.09 (limits −9.92 to 9.74), and the authors call the individual error large19. For scale, they note that gains of 1.75 to 3.5 mL/kg/min have been tied to lower mortality19. PubMed lists an October 2026 correction to this paper that I have not read.

What it predicts. In 122,007 adults referred for treadmill testing, elite versus low fitness carried an adjusted mortality hazard ratio of 0.20 (95% CI 0.16 to 0.24), and low fitness was comparable to or worse than coronary artery disease (1.29), smoking (1.41), or diabetes (1.40)1. In 750,302 US veterans followed a median 10.2 years, risk was lowest at about 14.0 METs, and the least fit (20th percentile) had a hazard ratio of 4.09 compared with the extremely fit23. Across 33 cohorts, each 1-MET higher capacity went with a relative risk of death of 0.8724; a digest of that paper puts low fitness under 7.9 METs and high at 10.9 or more21. The American Heart Association calls for treating fitness as a clinical vital sign25. All of this is observational. Training does move the number: across 28 trials, endurance training raised VO2 max 4.9 mL/kg/min compared with no exercise26.

Where. Clinicians use CPET for heart failure, other heart conditions, and unexplained exercise intolerance20. DexaFit lists a VO2 max test of about 15 minutes18.

Spirometry

What it measures. FVC is the volume blown out as forcefully and completely as possible from a full breath in, and FEV1 is the volume in the first second22.

How precise. The ATS and ERS standard requires at least three acceptable maneuvers, with the two largest FVC and FEV1 values within 0.150 L of each other, allows up to eight tries in adults, holds spirometers to ±2.5% accuracy, and makes the Global Lung Function Initiative equations the default reference22.

What it predicts. In 126,359 adults aged 35 to 70 in 17 countries, mild, moderate, and severe FEV1 impairment carried mortality hazard ratios of 1.27, 1.74, and 2.544. In the 15-year Renfrew and Paisley study, the lowest fifth of FEV1 had all-cause hazard ratios of 1.92 in men and 1.89 in women, against a comparison group the abstract doesn't name27. Both are observational. The USPSTF recommends against screening adults without symptoms for COPD (grade D)28.

Resting metabolic rate

An RMR test measures resting metabolic rate by indirect calorimetry; the evidence-based protocol is 10 minutes, discarding the first 5, with a coefficient of variation under 10% over the last 529. Of four common equations, Mifflin-St Jeor most often landed within 10% of the measured value in healthy nonobese and obese adults, in a review that didn't cover athletes or very low-carb eaters30. With no outcome data, I treat RMR as a check on an equation. DexaFit lists an RMR test of about 15 minutes18.

Grip strength and the sit-to-rise test

Grip. In 139,691 adults in 17 countries, each 5 kg lower grip strength went with a hazard ratio of 1.16 for death from any cause and 1.17 for cardiovascular death; that shows prediction, not that training grip changes outcomes5. The European sarcopenia consensus flags grip under 27 kg for men and under 16 kg for women, and more than 15 seconds for five chair rises15.

Sit-to-rise. Sit down on the floor and stand back up, scored 0 to 10, losing a point for each hand or knee used6. In a retrospective cohort of 2,002 adults aged 51 to 80 (68% men), 159 died over a median 6.3 years; each point higher went with 21% better survival, and the three lower score bands (0 to 3, 3.5 to 5.5, and 6 to 7.5) carried adjusted hazard ratios of 5.44, 3.44, and 1.846.

Home blood pressure

The American Heart Association and American Medical Association call home monitoring a validated out-of-office method, used for white-coat, masked, resistant, and morning hypertension; they prefer validated oscillometric devices with a standardized protocol, and report that home monitoring lowers pressure and improves control, most of all alongside other support31. The 2025 AHA/ACC guideline replaced the 2017 one32. The AHA's news release says it recommends home monitoring to confirm an office diagnosis and track progress, defines high blood pressure as 130/80 mm Hg or higher, and keeps normal at under 120/807. Across 123 trials, each 10 mm Hg lower systolic pressure cut major cardiovascular events (RR 0.80)33, and SPRINT's under-120 target cut its primary outcome at the cost of more fainting and kidney injury34.

Coronary calcium and CT angiography

These get full treatment on Heart; here is the short version. A calcium scan takes under 20 minutes with no contrast injection and scores calcified plaque from 0 (none) to over 400 (extensive); guidelines suggest considering it for men 40 and older and women 45 and older at borderline or intermediate risk, and not every insurance plan covers it35. In 5,800 statin-naive adults followed 9.5 years, the roughly one-third of statin-eligible people with a score of 0 had cardiovascular mortality of 0.2%, against 2.4% with any calcium, an observational result36. The dose is about 1.7 mSv for a calcium scan and 8.7 mSv for coronary CT angiography, against 0.1 mSv for a chest x-ray16. The main CT angiography trial, SCOT-HEART, enrolled people with stable chest pain, not healthy people37.

Sleep apnea testing at home

I take Nuvigil. Its FDA label covers excessive sleepiness from obstructive sleep apnea, narcolepsy, or shift work disorder; in sleep apnea it treats the sleepiness, not the obstruction, and when CPAP is the treatment of choice, the label calls for a maximal effort with CPAP first38.

The American Academy of Sleep Medicine says questionnaires and prediction tools shouldn't diagnose sleep apnea on their own. For uncomplicated adults at increased risk of moderate to severe disease, it recommends polysomnography or a home sleep apnea test on a technically adequate device, with polysomnography after a negative, inconclusive, or inadequate home test, and in place of one for people with significant heart or lung disease, chronic opioid use, a prior stroke, or severe insomnia39. In 2007 to 2010 data, 13% of men and 6% of women aged 30 to 70 had moderate to severe sleep apnea, yet the USPSTF finds the evidence insufficient to judge screening adults without recognized symptoms40.

Hearing

Nearly 16% of US adults report trouble hearing41, and about one in three people aged 65 to 74 has hearing loss; audiologists are trained to identify and measure it, and otolaryngologists diagnose and treat its causes42. The USPSTF finds the evidence insufficient to judge screening adults 50 and older41. In the ACHIEVE trial of 977 adults aged 70 to 84 with hearing loss, a hearing intervention made no overall difference in 3-year cognitive decline (p=0.96), though the effect differed between participants at higher risk of decline and healthy volunteers (p for interaction 0.010), so any dementia benefit is unconfirmed43.

Whole-body MRI

In a systematic review of 12 studies with 5,373 people without symptoms, a pooled 32.1% had critical or indeterminate findings, the pooled false-positive proportion was 16.0%, and no included study verified negative scans beyond 5 years44. A review of 12 cancer-screening studies covering 6,214 scans found abnormal findings in 95% of people, findings needing more workup in 30%, suspected cancer in 1.8%, and confirmed cancer in 1.1%45. The American College of Radiology says there is no documented evidence that total body screening is cost-efficient or prolongs life, and it worries about unnecessary follow-up tests and procedures8. A July 2026 RSNA news report describes use spreading among healthy people while radiology leaders warn that evidence of benefit is still limited46. Prenuvo, a seller, says its scan takes under an hour with no radiation or contrast, and its page lists "Whole Body MRI, blood biomarker testing and personalized results reviews" starting at $1,19947.

Rhonda Patrick on VO2 max and fitness testing

Rhonda Patrick, PhD, has covered fitness on FoundMyFitness. Her interview with Benjamin Levine, MD, covers how inactivity ages the heart and how VO2 max relates to longevity48, and a Journal Club episode with Brady Holmer includes a segment on VO2 max decline49. Her Science Digest summarizes a study in which a submaximal bike test predicted 5-year mortality in more than 58,000 UK Biobank adults50, along with the 33-study meta-analysis above21. I read show notes and summaries, not transcripts, and none of this means she endorses me or this site.

Cautions

  • The fitness, grip, sit-to-rise, and lung results are observational: people who score well may be healthier in ways the studies can't fully adjust for1,5,6,4.
  • CT carries radiation, MRI turns up incidental findings, and a finding can lead to more tests16,44.
  • A change between DEXA scans means little unless it beats the facility's least significant change, on the same machine with the same preparation2,10.
  • The BodySpec, DexaFit, and Prenuvo pages are marketing, current as of November 20269,18,47.
  • This is information, not medical advice. Which tests fit a person is a decision for a doctor.

References

  1. Mandsager K, Harb S, Cremer P, Phelan D, Nissen SE, Jaber W. Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing. JAMA Network Open. 2018;1(6):e183605.Cohort studyPubMed 30646252 · DOI

    What it found: Retrospective cohort of 122,007 adults (mean age 53.4) referred for treadmill testing at one Cleveland clinic from 1991 to 2014, followed a median of 8.4 years with 13,637 deaths. Elite fitness versus low fitness carried an adjusted mortality hazard ratio of 0.20 (95% CI 0.16 to 0.24), and elite versus high fitness 0.77 (0.63 to 0.95); low fitness was comparable to or worse than coronary artery disease (HR 1.29), smoking (1.41), or diabetes (1.40).

    Limits: Retrospective, single-center, and observational, in people referred for treadmill testing, so it shows association rather than proof that raising fitness lowers death risk.

  2. International Society for Clinical Densitometry. Official Adult Positions. International Society for Clinical Densitometry (ISCD). 2023.Position standRead

    What it found: ISCD adult positions (approved August 24, 2023): scan the PA spine and hip, define osteoporosis as a T-score of -2.5 or less in postmenopausal women and men 50 and older, set minimum technologist precision for body composition at 3% for total fat mass and 2% for total lean mass and percent fat mass, and list body-composition indications including large planned weight loss and muscle weakness (outcome impact uncertain for the last two).

    Limits: A professional society's rules for clinical densitometry; the page shows no last-updated date (copyright August 2023) and does not show that DXA body composition improves outcomes in healthy people.

  3. Kaul S, Rothney MP, Peters DM, Wacker WK, Davis CE, Shapiro MD, et al. Dual-energy X-ray absorptiometry for quantification of visceral fat. Obesity (Silver Spring, Md.). 2012;20(6):1313-1318.Cross-sectional studyPubMed 22282048 · DOI

    What it found: Validation study in 124 adults aged 18 to 90 with BMI 18.5 to 40 who had DXA and CT within an hour. DXA visceral fat volume tracked CT closely (r2 0.957 combined) but the combined 95% limits of agreement were -355 to +468 cm3 around a mean difference of 56 cm3.

    Limits: One research dataset with a BMI cap of 40, and CT is the comparison standard, so it shows agreement for groups better than it pins down one person's volume.

  4. Duong M, Islam S, Rangarajan S, Leong D, Kurmi O, Teo K, et al. Mortality and cardiovascular and respiratory morbidity in individuals with impaired FEV1 (PURE): an international, community-based cohort study. The Lancet. Global Health. 2019;7(5):e613-e623.Cohort studyPubMed 31000131 · DOI

    What it found: PURE cohort of 126,359 adults aged 35 to 70 in 17 countries followed a median 7.8 years. Mortality hazard ratios were 1.27 (95% CI 1.18 to 1.36), 1.74 (1.60 to 1.90), and 2.54 (2.26 to 2.86) for mild, moderate, and severe FEV1 impairment, with cardiovascular hazard ratios of 1.18, 1.39, and 2.02.

    Limits: Observational, with impairment defined against country-specific means, so it shows that low FEV1 marks higher risk, not that improving FEV1 lowers it.

  5. Leong DP, Teo KK, Rangarajan S, Lopez-Jaramillo P, Avezum A Jr, Orlandini A, et al. Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study. The Lancet. 2015;386(9990):266-273.Cohort studyPubMed 25982160 · DOI

    What it found: Prospective cohort of 139,691 adults in 17 countries followed a median 4.0 years with 3,379 deaths. Per 5 kg lower grip strength, the hazard ratio was 1.16 (95% CI 1.13 to 1.20) for all-cause mortality, 1.17 (1.11 to 1.24) for cardiovascular mortality, 1.07 (1.02 to 1.11) for myocardial infarction, and 1.09 (1.05 to 1.15) for stroke; grip predicted all-cause and cardiovascular death better than systolic blood pressure.

    Limits: Observational with a short median follow-up, and it shows grip strength predicts outcomes, not that training grip changes them.

  6. Brito LB, Ricardo DR, Araújo DSMS de, Ramos PS, Myers J, Araújo CGS de. Ability to sit and rise from the floor as a predictor of all-cause mortality. European Journal of Preventive Cardiology. 2014;21(7):892-898.Cohort studyPubMed 23242910 · DOI

    What it found: Retrospective cohort of 2,002 adults aged 51 to 80 who did a sitting-rising test scored 0 to 10 (a point lost for each hand or knee support). Over a median 6.3 years there were 159 deaths; lower scores meant higher mortality (p < 0.001), each one-point rise went with a 21% survival improvement, and adjusted hazard ratios for the three lower score groups were 5.44, 3.44, and 1.84.

    Limits: One Brazilian clinic cohort of mostly men (68%) in a narrow age range, with 159 deaths, and the abstract does not name the reference group.

  7. American Heart Association. New high blood pressure guideline emphasizes prevention, early treatment to reduce CVD risk. EurekAlert! (American Heart Association news release), August 14, 2025.ArticleRead

    What it found: News release on the 2025 AHA/ACC guideline: home blood pressure monitoring is recommended to confirm an office diagnosis and track progress; high blood pressure is 130/80 mm Hg or higher (stage 1 is 130 to 139 or 80 to 89, stage 2 is 140 or 90 and higher), normal is under 120/80, and the systolic goal for adults with high blood pressure is under 130.

    Limits: A press release summarizing the guideline, and it does not mention validated or cuffless devices.

  8. American College of Radiology. ACR Statement on Screening Total Body MRI. American College of Radiology. 2023.Position standRead

    What it found: ACR statement (April 17, 2023): it does not believe there is sufficient evidence to justify recommending total body screening for people with no symptoms, risk factors, or family history, says there is no documented evidence that it is cost-efficient or effective in prolonging life, and worries it would lead to unnecessary follow-up testing and procedures.

    Limits: A 2023 professional-society position that the ACR says it will keep monitoring, so newer evidence may change it.

  9. BodySpec. Full-body DEXA scans for body fat & muscle analysis | BodySpec. BodySpec, November 5, 2026.Product pageRead

    What it found: Company page offering full-body DEXA scans (body fat percentage by area, lean mass, visceral fat, bone density) at 100+ US locations, bookable without a doctor's referral; its FAQ says it cut the cost of a DEXA scan from $300 to as low as $39.

    Limits: A seller's own marketing page checked on the date shown; prices vary by location and the page makes no accuracy or radiation claim.

  10. Nana A, Slater GJ, Stewart AD, Burke LM. Methodology review: using dual-energy X-ray absorptiometry (DXA) for the assessment of body composition in athletes and active people. International Journal of Sport Nutrition and Exercise Metabolism. 2015;25(2):198-215.ReviewPubMed 25029265 · DOI

    What it found: Review of the sources of error and variability in DXA body composition in athletes and active people, proposing a standardized scan protocol covering subject preparation, positioning aids, and adjustment of automatic regional segmentation, plus reporting requirements for studies.

    Limits: A methodology review whose abstract gives no numbers, so it shows why scans must be standardized but not how large each error is.

  11. Achamrah N, Colange G, Delay J, Rimbert A, Folope V, Petit A, et al. Comparison of body composition assessment by DXA and BIA according to the body mass index: A retrospective study on 3655 measures. PLoS ONE. 2018;13(7):e0200465.Cross-sectional studyPubMed 30001381 · DOI

    What it found: Retrospective comparison of 3,655 DXA and bioimpedance (BIA) measures taken fasting in 2010 to 2016. At BMI 16 to 18.5 the two agreed within 1 kg, but above 18.5 and up to 40 BIA overestimated fat-free mass by 3.38 to 8.28 kg and underestimated fat mass by 2.51 to 5.67 kg.

    Limits: A retrospective single-device comparison that treats DXA as the reference, in a clinical population, so it does not show how a modern multi-frequency scale performs in a lean, trained person.

  12. Coëffier M, El Machkouri M, L'Huillier C, Folope V, Lelandais H, Grigioni S, et al. Accuracy of bioimpedance equations for measuring body composition in a cohort of 2134 patients with obesity. Clinical Nutrition (Edinburgh, Scotland). 2022;41(9):2013-2024.Cross-sectional studyPubMed 35970132 · DOI

    What it found: Retrospective test of seven bioimpedance equations against DXA in 2,134 patients with BMI of 30 or higher. The Roubenoff equation for fat-free mass was within 10% of DXA in 75.7% of class I and II patients and 83.3% of class III patients, with 95% limits of agreement of -9.42 to 5.49 kg and -8.16 to 6.52 kg.

    Limits: Only people with obesity from a clinical cohort, so it says little about lean or athletic adults.

  13. Marshall D, Johnell O, Wedel H. Meta-analysis of how well measures of bone mineral density predict occurrence of osteoporotic fractures. BMJ (Clinical research ed.). 1996;312(7041):1254-1259.Meta-analysisPubMed 8634613 · DOI

    What it found: Meta-analysis of eleven prospective study populations (about 90,000 person-years, over 2,000 fractures). Each 1 standard deviation lower bone density raised fracture risk 1.5-fold (95% CI 1.4 to 1.6), vertebral fracture risk 2.3-fold with a spine measurement, and hip fracture risk 2.6-fold with a hip measurement.

    Limits: A 1996 pooling of older cohorts; bone density predicts fractures but, as the abstract's comparison with blood pressure and cholesterol shows, it is a risk marker and not a diagnosis of who will fracture.

  14. US Preventive Services Task Force, Nicholson WK, Silverstein M, Wong JB, Chelmow D, Coker TR, et al. Screening for Osteoporosis to Prevent Fractures: US Preventive Services Task Force Recommendation Statement. JAMA. 2025;333(6):498-508.GuidelinePubMed 39808425 · DOI

    What it found: USPSTF recommends screening for osteoporosis in women 65 and older and in postmenopausal women younger than 65 at increased risk (both grade B), and finds the evidence insufficient to assess screening in men (I statement).

    Limits: A recommendation about screening to prevent fractures; it says nothing about DXA lean or fat mass.

  15. Cruz-Jentoft AJ, Bahat G, Bauer J, Boirie Y, Bruyère O, Cederholm T, et al. Sarcopenia: revised European consensus on definition and diagnosis. Age and Ageing. 2019;48(1):16-31.Position standPubMed 30312372 · DOI

    What it found: European consensus (EWGSOP2) that makes low muscle strength the key characteristic of sarcopenia, confirms it with low muscle quantity or quality, marks poor physical performance as severe, updates the case-finding algorithm, and provides cut-off points.

    Limits: A consensus statement for older adults; the grip, chair-stand, and muscle-mass cut-offs used on the page come from its full text (PMC6322506, Table 3), not the abstract.

  16. RadiologyInfo.org. Radiation Dose from X-Ray and CT Exams. RadiologyInfo.org, April 15, 2025.ArticleRead

    What it found: Dose table (last reviewed April 15, 2025): bone densitometry 0.001 mSv (about 3 hours of natural background), cardiac CT for calcium scoring 1.7 mSv (6 months), coronary CT angiography 8.7 mSv (3 years), chest x-ray 0.1 mSv (10 days); average US background is about 3 mSv a year.

    Limits: Typical values for an average-sized adult; actual doses vary by scanner and protocol.

  17. RadiologyInfo.org. Bone Density Scan (DEXA or DXA). RadiologyInfo.org, March 11, 2024.ArticleRead

    What it found: Patient page (last reviewed March 11, 2024): a DEXA scan uses a very small dose of radiation, less than one-tenth that of a standard chest x-ray, and the central test usually takes 10 to 30 minutes; a T-score of -1 and above is normal, -1.1 to -2.4 is low bone mass, and -2.5 and below is osteoporosis; calcium supplements are avoided for 24 hours before.

    Limits: A patient-education page about bone density scans, not about whole-body body-composition protocols, and it gives no millisievert figure.

  18. DexaFit. Get DexaFit | The Leader in DEXA Scans, VO2 Max, RMR, and Lab Testing. DexaFit, November 5, 2026.Product pageRead

    What it found: Company page offering a DEXA body composition scan (about 8 minutes), VO2max testing (about 15 minutes), RMR metabolic analysis (about 15 minutes), and blood biomarker panels across a network in 41 states, with locations independently owned and operated.

    Limits: A seller's own marketing page checked on the date shown; it lists no prices.

  19. Molina-Garcia P, Notbohm HL, Schumann M, Argent R, Hetherington-Rauth M, Stang J, et al. Validity of Estimating the Maximal Oxygen Consumption by Consumer Wearables: A Systematic Review with Meta-analysis and Expert Statement of the INTERLIVE Network. Sports Medicine (Auckland, N.Z.). 2022;52(7):1577-1597.Meta-analysisPubMed 35072942 · DOI

    What it found: Meta-analysis of fourteen validation studies of consumer wearables that estimate VO2max. Devices using resting-condition information overestimated VO2max (bias 2.17 ml/kg/min; limits of agreement -13.07 to 17.41), while devices using exercise-based information had lower error (bias -0.09; limits -9.92 to 9.74), and the authors say individual-level error is still large.

    Limits: A published erratum for this paper appeared in October 2026 (PMID 42867627) and I could not read what it changed, so the numbers are from the 2022 abstract and may have been revised.

  20. Albouaini K, Egred M, Alahmar A, Wright DJ. Cardiopulmonary exercise testing and its application. Heart. 2007;93(10):1285-1292.ReviewPubMed 17890705 · DOI

    What it found: Review describing cardiopulmonary exercise testing as a clinical tool that measures how the lungs, heart and circulation, and skeletal muscles work together to judge exercise capacity and predict outcomes, covering the physiology, test method, indications and contraindications, and interpretation.

    Limits: A 2007 review centered on heart failure; the page cites only what its abstract states.

  21. FoundMyFitness. Poor cardiorespiratory fitness linked to 70 percent higher risk of premature death and 56 percent greater heart and cardiovascular disease risk. FoundMyFitness Science Digest, September 22, 2023.ArticleRead

    What it found: Science Digest item on the 2009 JAMA meta-analysis of 33 studies: low fitness (under 7.9 METs) carried a 70% higher risk of premature death than high fitness (10.9 METs or more) and a 56% higher risk of heart and cardiovascular events, and each 1-MET gain roughly matches a 1 km/h faster running speed.

    Limits: A summary page, not the paper, and the date is the page's 'updated' date, not the original posting date.

  22. Graham BL, Steenbruggen I, Miller MR, Barjaktarevic IZ, Cooper BG, Hall GL, et al. Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement. American Journal of Respiratory and Critical Care Medicine. 2019;200(8):e70-e88.Position standPubMed 31613151 · DOI

    What it found: Joint American Thoracic Society and European Respiratory Society technical statement that updates the 2005 spirometry standards for instruments, operators, quality assurance, and the patient experience, with recommendations for manufacturers, clinicians, operators, and researchers.

    Limits: A measurement standard, not a study of what results predict; the repeatability, calibration, and reference-equation details used on the page come from the full text (PMC6794117), not the abstract.

  23. Kokkinos P, Faselis C, Samuel IBH, Pittaras A, Doumas M, Murphy R, et al. Cardiorespiratory Fitness and Mortality Risk Across the Spectra of Age, Race, and Sex. Journal of the American College of Cardiology. 2022;80(6):598-609.Cohort studyPubMed 35926933 · DOI

    What it found: Cohort of 750,302 US veterans aged 30 to 95 followed a median 10.2 years (174,807 deaths). Mortality was lowest at about 14.0 METs (hazard ratio 0.24 for men, 0.23 for women), and the least fit 20th percentile had a hazard ratio of 4.09 (95% CI 3.90 to 4.20) versus the extremely fit group.

    Limits: Observational and mostly male (45,232 women), so fitter people may differ in other ways, and it cannot show that raising fitness lowers an individual's risk.

  24. Kodama S, Saito K, Tanaka S, Maki M, Yachi Y, Asumi M, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. JAMA. 2009;301(19):2024-2035.Meta-analysisPubMed 19454641 · DOI

    What it found: Random-effects meta-analysis of 33 cohort studies (102,980 participants for all-cause mortality, 6,910 deaths). Each 1-MET higher maximal aerobic capacity went with a relative risk of 0.87 (95% CI 0.84 to 0.90) for all-cause mortality and 0.85 (0.82 to 0.88) for coronary or cardiovascular events; low versus high fitness (under 7.9 vs 10.9 METs or more) was 1.70 (1.51 to 1.92) for all-cause mortality.

    Limits: Pooled observational cohorts, so fitness may partly mark healthy people rather than cause the lower risk, and it says nothing about which training method works best.

  25. Ross R, Blair SN, Arena R, Church TS, Després JP, Franklin BA, et al. Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association. Circulation. 2016;134(24):e653-e699.Position standPubMed 27881567 · DOI

    What it found: American Heart Association scientific statement arguing that low cardiorespiratory fitness may predict mortality more strongly than smoking, high blood pressure, high cholesterol, and type 2 diabetes, that adding fitness to traditional risk factors improves risk classification, and that clinicians should assess it as a vital sign.

    Limits: An expert review, not a new study; the abstract calls it a focused review of key advances and gives no numbers.

  26. Milanović Z, Sporiš G, Weston M. Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Medicine. 2015;45(10):1469-1481.Meta-analysisPubMed 26243014 · DOI

    What it found: Meta-analysis of 28 controlled trials (723 healthy adults aged 18 to 45, mean baseline VO2max 40.8 mL/kg/min). VO2max rose 4.9 mL/kg/min with endurance training and 5.5 with high-intensity intervals versus no exercise, and intervals beat endurance training by 1.2 mL/kg/min (95% confidence limits 0.9).

    Limits: Young and middle-aged healthy adults only, mostly short trials, and a small average edge for intervals over endurance work.

  27. Hole DJ, Watt GC, Davey-Smith G, Hart CL, Gillis CR, Hawthorne VM. Impaired lung function and mortality risk in men and women: findings from the Renfrew and Paisley prospective population study. BMJ (Clinical research ed.). 1996;313(7059):711-716.Cohort studyPubMed 8819439 · DOI

    What it found: Prospective cohort of 7,058 men and 8,353 women aged 45 to 64 screened in 1972 to 1976 and followed 15 years. Men and women in the lowest fifth of FEV1 had relative hazards for all-cause death of 1.92 (95% CI 1.68 to 2.20) and 1.89 (1.63 to 2.20), with raised hazards for ischemic heart disease, stroke, and lung cancer.

    Limits: A 1970s observational cohort whose abstract does not name the comparison group for the lowest fifth, so I report the hazards without one.

  28. US Preventive Services Task Force, Mangione CM, Barry MJ, Nicholson WK, Cabana M, Caughey AB, et al. Screening for Chronic Obstructive Pulmonary Disease: US Preventive Services Task Force Reaffirmation Recommendation Statement. JAMA. 2022;327(18):1806-1811.GuidelinePubMed 35536260 · DOI

    What it found: USPSTF reaffirmation: with moderate certainty, screening asymptomatic adults for COPD has no net benefit, and it recommends against it (grade D); about 6% of US adults had been diagnosed with COPD in 2020.

    Limits: It concerns screening people without symptoms and does not cover diagnostic spirometry for someone with breathing symptoms.

  29. Compher C, Frankenfield D, Keim N, Roth-Yousey L, Evidence Analysis Working Group. Best practice methods to apply to measurement of resting metabolic rate in adults: a systematic review. Journal of the American Dietetic Association. 2006;106(6):881-903.Systematic reviewPubMed 16720129 · DOI

    What it found: Systematic review of how to measure resting metabolic rate by indirect calorimetry: a 10-minute test, discarding the first 5 minutes, with a coefficient of variation under 10% across the remaining 5 minutes, gave accurate readings.

    Limits: A 2006 evidence-analysis review of test technique that does not say how well one reading predicts anything about health.

  30. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association. 2005;105(5):775-789.Systematic reviewPubMed 15883556 · DOI

    What it found: Systematic review of four commonly used resting metabolic rate equations (Harris-Benedict, Mifflin-St Jeor, Owen, and WHO/FAO/UNU) in healthy nonobese and obese adults: Mifflin-St Jeor was most likely to estimate RMR within 10% of the measured value.

    Limits: The abstract gives no percentages, and it covers healthy adults, not trained athletes or people on very low-carbohydrate diets.

  31. Shimbo D, Artinian NT, Basile JN, Krakoff LR, Margolis KL, Rakotz MK, et al. Self-Measured Blood Pressure Monitoring at Home: A Joint Policy Statement From the American Heart Association and American Medical Association. Circulation. 2020;142(4):e42-e63.Position standPubMed 32567342 · DOI

    What it found: Joint AHA and AMA policy statement calling self-measured home blood pressure a validated out-of-office method useful for white-coat, masked, resistant, and morning hypertension, preferring validated oscillometric devices with a standardized protocol, and reporting that it lowers blood pressure and improves control, especially with co-interventions.

    Limits: A policy statement whose abstract gives no thresholds or device criteria, and a correction to it was published (PMID 32718246).

  32. Writing Committee Members, Jones DW, Ferdinand KC, Taler SJ, Johnson HM, Shimbo D, et al. 2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ASPC/NMA/PCNA/SGIM Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2025;152(11):e114-e218.GuidelinePubMed 40811497 · DOI

    What it found: The guideline that replaces the 2017 ACC/AHA high blood pressure guideline, built on a literature search from December 2023 to June 2024 and designed as a living document; published online in August 2025.

    Limits: I read the PubMed record and the ACC press release, not the full guideline, so the thresholds I quote come from the press release.

  33. Ettehad D, Emdin CA, Kiran A, Anderson SG, Callender T, Emberson J, et al. Blood pressure lowering for prevention of cardiovascular disease and death: a systematic review and meta-analysis. Lancet (London, England). 2016;387(10022):957-967.Meta-analysisPubMed 26724178 · DOI

    What it found: Meta-analysis of 123 trials with 613,815 participants. Each 10 mm Hg lower systolic pressure cut major cardiovascular events (RR 0.80, 95% CI 0.77 to 0.83), coronary heart disease (0.83), stroke (0.73), heart failure (0.72), and all-cause mortality (0.87, 0.84 to 0.91).

    Limits: Pools trials of drug treatment, so it shows what lowering pressure with medication does, not what diet or exercise alone would do.

  34. SPRINT Research Group, Wright JT Jr, Williamson JD, Whelton PK, Snyder JK, Sink KM, et al. A Randomized Trial of Intensive versus Standard Blood-Pressure Control. The New England Journal of Medicine. 2015;373(22):2103-2116.Randomized trialPubMed 26551272 · DOI

    What it found: SPRINT randomized 9,361 adults without diabetes, with systolic pressure of 130 mm Hg or higher and increased cardiovascular risk, to a systolic target under 120 or under 140 mm Hg. Over a median 3.26 years (stopped early), the primary composite outcome was 1.65% versus 2.19% per year (HR 0.75, 95% CI 0.64 to 0.89) and all-cause death HR was 0.73 (0.60 to 0.90).

    Limits: Excluded people with diabetes and prior stroke, was stopped early, and the intensive arm had more hypotension, syncope, electrolyte abnormalities, and acute kidney injury.

  35. RadiologyInfo.org. Cardiac CT for Calcium Scoring. RadiologyInfo.org, July 15, 2026.ArticleRead

    What it found: Patient page (last reviewed July 15, 2026): the scan takes less than 20 minutes with no contrast injection, may be recommended for people with risk factors but no symptoms, with guidelines suggesting men 40 and older and women 45 and older at borderline or intermediate risk; scores run 0 (no evidence of CAD) through over 400 (extensive); not all insurance plans cover it.

    Limits: A patient-education page that gives no cost figures.

  36. Rajan T, Rozanski A, Cainzos-Achirica M, Grandhi GR, Dardari ZA, Al-Mallah MH, et al. Relation of Absence of Coronary Artery Calcium to Cardiovascular Disease Mortality Risk Among Individuals Meeting Criteria for Statin Therapy According to the 2018/2019 ACC/AHA Guidelines. The American Journal of Cardiology. 2020;136:49-55.Cohort studyPubMed 32941817 · DOI

    What it found: Observational study of 5,800 statin-naive adults aged 40 to 75 without known coronary disease followed 9.5 years. About one-third of those meeting statin criteria had a calcium score of 0, and their cardiovascular mortality was 0.2% versus 2.4% for those with any calcium (about 12-fold lower).

    Limits: Observational and showing risk, not that skipping a statin is safe, and the abstract does not name the clinic or say how many people had scores in each range.

  37. SCOT-HEART Investigators, Newby DE, Adamson PD, Berry C, Boon NA, Dweck MR, et al. Coronary CT Angiography and 5-Year Risk of Myocardial Infarction. The New England Journal of Medicine. 2018;379(10):924-933.Randomized trialPubMed 30145934 · DOI

    What it found: SCOT-HEART randomized 4,146 patients with stable chest pain to standard care plus coronary CT angiography or standard care alone, with a median follow-up of 4.8 years. Death from coronary heart disease or nonfatal heart attack at 5 years was 2.3% versus 3.9% (HR 0.59, 95% CI 0.41 to 0.84), with no difference in invasive angiography (HR 1.00) or revascularization (HR 1.07).

    Limits: Patients had stable chest pain, so the result does not apply to screening people with no symptoms.

  38. Cephalon, LLC. NUVIGIL (ARMODAFINIL) TABLET [CEPHALON, LLC]. DailyMed, National Library of Medicine (FDA-approved prescribing information), May 7, 2025.Regulatory noticeRead

    What it found: FDA-approved label for Nuvigil (armodafinil), a DEA Schedule IV drug indicated to improve wakefulness in adults with excessive sleepiness from obstructive sleep apnea, narcolepsy, or shift work disorder. It lists 150 mg to 250 mg once a day in the morning for sleep apnea or narcolepsy and 150 mg about one hour before a work shift for shift work disorder, an apparent terminal half-life of about 15 hours, and placebo-controlled adverse reactions of headache 17% versus 9%, nausea 7% versus 3%, dizziness 5% versus 2%, and insomnia 5% versus 1%. It warns of serious rash, DRESS, angioedema, psychiatric symptoms, and reduced effectiveness of steroidal contraceptives during treatment and for one month after stopping.

    Limits: A drug label, not a study; DailyMed lists this May 7, 2025 posting as current, and the label text itself reads Revised 12/2022.

  39. Kapur VK, Auckley DH, Chowdhuri S, Kuhlmann DC, Mehra R, Ramar K, et al. Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline. Journal of Clinical Sleep Medicine. 2017;13(3):479-504.GuidelinePubMed 28162150 · DOI

    What it found: AASM guideline: questionnaires and prediction tools should not be used to diagnose OSA without polysomnography or home testing (strong); uncomplicated adults at increased risk of moderate-to-severe OSA can be tested with polysomnography or a home sleep apnea test on a technically adequate device (strong); a negative, inconclusive, or inadequate home test should be followed by polysomnography (strong); polysomnography is preferred for significant cardiorespiratory disease, chronic opioid use, prior stroke, or severe insomnia (strong).

    Limits: A 2017 guideline on how to diagnose, not on who benefits from treatment, and its abstract reports no accuracy numbers.

  40. US Preventive Services Task Force, Mangione CM, Barry MJ, Nicholson WK, Cabana M, Chelmow D, et al. Screening for Obstructive Sleep Apnea in Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2022;328(19):1945-1950.GuidelinePubMed 36378202 · DOI

    What it found: USPSTF finds the evidence insufficient to assess screening for obstructive sleep apnea in the general adult population (I statement); in 2007 to 2010 data, 14% of men and 5% of women aged 30 to 70 had at least mild OSA (AHI 5 or higher) with daytime sleepiness, and 13% of men and 6% of women had moderate to severe OSA (AHI 15 or higher).

    Limits: It concerns screening people without recognized symptoms; it does not address testing someone with sleepiness or snoring.

  41. US Preventive Services Task Force, Krist AH, Davidson KW, Mangione CM, Cabana M, Caughey AB, et al. Screening for Hearing Loss in Older Adults: US Preventive Services Task Force Recommendation Statement. JAMA. 2021;325(12):1196-1201.GuidelinePubMed 33755083 · DOI

    What it found: USPSTF finds the evidence insufficient to assess the balance of benefits and harms of screening adults 50 and older for hearing loss (I statement); nearly 16% of US adults report difficulty hearing.

    Limits: An 'I' statement means the evidence is insufficient, not that testing is harmful, and it covers screening without symptoms.

  42. National Institute on Deafness and Other Communication Disorders. Age-Related Hearing Loss (Presbycusis). NIDCD, National Institutes of Health, March 17, 2023.ArticleRead

    What it found: NIH page (updated March 17, 2023): about one in three US adults 65 to 74 has hearing loss and nearly half of those older than 75 have difficulty hearing; audiologists have specialized training in identifying and measuring hearing loss and otolaryngologists look for causes and treatments.

    Limits: A public information page that does not describe the hearing test itself or mention dementia.

  43. Lin FR, Pike JR, Albert MS, Arnold M, Burgard S, Chisolm T, et al. Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE): a multicentre, randomised controlled trial. The Lancet (London, England). 2023;402(10404):786-797.Randomized trialPubMed 37478886 · DOI

    What it found: ACHIEVE randomized 977 adults aged 70 to 84 with untreated hearing loss (490 to hearing aids and counseling, 487 to health education) for 3 years. The primary outcome, 3-year change in global cognition, did not differ (-0.200 versus -0.202 SD, difference 0.002, 95% CI -0.077 to 0.081, p=0.96), though the effect differed between the two recruited cohorts (interaction p=0.010).

    Limits: The overall result was null and unmasked, and the possible benefit in the higher-risk cohort comes from a subgroup comparison that the authors present as a suggestion.

  44. Kwee RM, Kwee TC. Whole-body MRI for preventive health screening: A systematic review of the literature. Journal of Magnetic Resonance Imaging. 2019;50(5):1489-1503.Systematic reviewPubMed 30932247 · DOI

    What it found: Systematic review of 12 studies with 5,373 asymptomatic adults: pooled prevalence of critical and indeterminate findings combined was 32.1% (95% CI 18.3% to 50.1%), the pooled false-positive proportion was 16.0% (95% CI 1.9% to 65.8%, six studies), and verification data were lacking.

    Limits: Very wide confidence intervals and heterogeneity (I2 95.6 to 99.1), and no included study followed negative scans for 5 years, so it cannot give a true false-negative rate.

  45. Zugni F, Padhani AR, Koh DM, Summers PE, Bellomi M, Petralia G. Whole-body magnetic resonance imaging (WB-MRI) for cancer screening in asymptomatic subjects of the general population: review and recommendations. Cancer Imaging. 2020;20(1):34.ReviewPubMed 32393345 · DOI

    What it found: Review of 12 studies with 6,214 whole-body MRI examinations in asymptomatic people: 95% of subjects had abnormal findings, 30% had findings needing further investigation, cancer was suspected in 1.8%, and the overall rate of histologically confirmed cancer was 1.1%.

    Limits: The studies were too varied in design to say whether screening reduces cancer deaths, and the abstract does not report survival.

  46. Henderson M. Whole-Body MRI Expands, Leaving Patients Weighing Risks. RSNA News, July 1, 2026.ArticleRead

    What it found: RSNA news report (July 1, 2026): whole-body MRI is expanding as a screening tool for healthy patients while radiology leaders warn that evidence of clinical benefit remains limited; of about 160 patients in Weill Cornell's first 18 months, 90% had some finding and about 1% of findings were malignant or suspected malignant, and a radiologist quoted says the data do not yet show it extends lives.

    Limits: A news report quoting individual radiologists and one center's early numbers, not a study.

  47. Prenuvo. Prenuvo | See the full picture of your health with Whole Body MRI. Prenuvo, November 5, 2026.Product pageRead

    What it found: Company page offering a whole body MRI scan in under an hour with no radiation and no contrast, advertising whole body MRI, blood biomarker testing, and personalized results reviews starting at $1,199, and listing three add-on scans as FDA-cleared; the page does not say whether the whole body scan itself is FDA-cleared.

    Limits: A seller's own marketing page checked on the date shown; it lists no accuracy figures or limitations.

  48. Patrick R, Levine B. #090 How Exercise Prevents & Reverses Heart Aging | Benjamin Levine, M.D. FoundMyFitness, May 28, 2024.PodcastListen

    What it found: Rhonda Patrick interviews Benjamin Levine, MD (UT Southwestern); the show notes cover how inactivity ages the heart, structured exercise that may reverse some of it, VO2 max and longevity, intensity and volume, strength versus endurance work, and recovery and overtraining.

    Limits: Interview and show notes, not a study; the framing about reversing up to 20 years of heart aging is the episode's own, and I did not open a transcript.

  49. Patrick R, Holmer B. #108 The Best Type of Exercise for Longevity. FoundMyFitness, December 7, 2025.PodcastListen

    What it found: A Journal Club episode in which Rhonda Patrick and Brady Holmer review a Nature Communications study of over 70,000 adults on vigorous versus moderate activity; the notes list segments on the 1:2 intensity rule, whether zone 2 counts as vigorous, VO2 max decline, mitochondria, and the 80/20 rule.

    Limits: Show notes with timestamps only; the study under discussion is not one I opened, so I make no claim about its numbers.

  50. FoundMyFitness. Assessment of cardiorespiratory fitness using submaximal exercise testing predicts 5-year mortality risk beyond conventional risk factors. FoundMyFitness Science Digest #16, July 27, 2026.ArticleRead

    What it found: Science Digest item on a Mayo Clinic Proceedings study of more than 58,000 UK Biobank participants aged 40 to 69 who did a submaximal stationary bicycle test: fitness and risk of death were linearly related, and the test predicted death beyond conventional risk factors, especially in people with few of them.

    Limits: A summary page that gives no hazard ratios and no authors; the date is the page's 'updated' date, not the original posting date.