Activity Tracking

Regular physical activity is one of the most powerful things you can do for your health. It is linked to lower risk of heart disease, dementia, depression and early death. The harder question is how to know whether you are doing enough. Many people feel active but aren’t. Roughly 38% to 52% of US adults, depending on region, meet the aerobic activity guideline. No more than about 28% meet both the aerobic and strength guidelines [1].

A wearable can help. It won’t make you fit, but it can show you what you are really doing and nudge you to do a bit more. Here is how I think about the numbers.

The Numbers Worth Watching

1. Daily Steps

Steps are the simplest metric and one of the best studied. In a 2025 meta-analysis in The Lancet Public Health, people who averaged about 7,000 steps a day had a 47% lower risk of dying from any cause than people who averaged about 2,000. They also had a 25% lower risk of cardiovascular disease, 38% lower risk of dementia, 22% fewer depressive symptoms and 28% fewer falls. Most of the benefit came before 5,000 to 7,000 steps [2]. An earlier analysis found about 15% lower all-cause mortality for every additional 1,000 steps a day [3].

You do not need 10,000. If you currently average 3,000, aiming for 4,000 is a real win.

2. Active Minutes

Active minutes (Apple’s Exercise Minutes, Fitbit’s Active Zone Minutes, and similar) track time spent at moderate or vigorous effort. This is the number that maps most directly to the national guideline of 150 minutes of moderate activity or 75 minutes of vigorous activity per week, plus muscle-strengthening on two days [4].

3. Estimated Fitness (VO2 Max)

Many watches now estimate VO2 max, a measure of how well your body uses oxygen. Treat the number as a rough guide, not a lab result. The underlying science is strong. In a study of 122,007 adults who had treadmill testing, low fitness was associated with about five times the risk of death compared with elite fitness. The mortality risk of below-average fitness was comparable to or greater than that of smoking, diabetes or coronary disease, and there was no upper limit of benefit [5]. A separate analysis found the least fit adults had roughly four times the risk of the most fit, with no sign of harm at the highest fitness levels [6]. Watch the trend over months, not the day-to-day value.

4. Training Load and Recovery

Load and recovery scores (WHOOP, Garmin and others) can help you notice when you are stacking hard days and not recovering. They are most useful for people training for events. Most of us do better listening to our bodies: sleep, mood, soreness and energy.

5. Sitting Time

Even active people can sit too long. In a large UK Biobank analysis, sitting more than about 10.6 hours a day was associated with higher risk of heart failure (hazard ratio 1.45) and cardiovascular death (hazard ratio 1.62). The risk remained even among people who met the exercise guidelines [7]. Breaking up long sits matters as much as the workout itself.

Small Bursts Count

If you don’t exercise, short bursts of vigorous effort during daily life may help. In wrist-tracker data from people who did not exercise, about three bouts a day of 1 to 2 minutes (such as climbing stairs briskly or walking fast to the bus) were linked to 38% to 40% lower all-cause mortality [8]. This is an observational finding, so it shows association, not proof. Still, it is a good reason to take the stairs.

A Considered Approach

  • Aim for the guideline. 150 minutes of moderate or 75 minutes of vigorous activity each week, plus strength training two days a week [4].
  • Start from your baseline. Look at your average steps for a week and add 500 to 1,000 per day. Build gradually.
  • Use the talk test. Moderate effort means you can talk but not sing. Heart-rate zones (such as Zone 2) are a useful extra for those who like data.
  • Check VO2 max every few months, not daily.
  • Interrupt sitting. Stand up and move for a few minutes every hour.
  • Celebrate consistency over perfection.

If You Have Been Sedentary

Start where you are. Add a 5 to 10 minute walk after a meal. Build toward 20 to 30 minutes most days. If you have heart disease, diabetes, chest pain, dizziness or other medical conditions, or you are returning after a long break, check with your doctor before increasing intensity.

What Trackers Can Do, and What They Can’t

Reviews of randomized trials show that trackers can increase activity. In older adults, trackers raised physical activity time and daily steps compared with usual care. They did not significantly change BMI, body fat or physical function [9]. Among people with coronary artery disease in cardiac rehabilitation, wearables added about 1,060 steps a day and were associated with fewer rehospitalizations [10]. In children and adolescents, trackers increased steps but not moderate-to-vigorous activity [11].

Two cautions apply. Consumer devices estimate calories, heart rate zones, VO2 max and recovery, and the estimates vary by brand and by person. And a tracker is a tool, not a verdict. If numbers cause stress or guilt, take a break from checking them.

The Bottom Line

The best tracker is the one you will actually wear and the one that gets you moving. Pick one or two metrics, such as daily steps and weekly active minutes, and let them guide you. Everything else is optional.

This article is for general education and is not medical advice. Talk with your own doctor before starting or changing an exercise program, especially if you have a medical condition or symptoms.

References

Study details retrieved from PubMed.

  1. Watson KB, et al. Physical activity guideline adherence among US adults. MMWR 2020. DOI
  2. Ding D, et al. Daily steps and health outcomes: a systematic review and meta-analysis. Lancet Public Health 2025. DOI
  3. Banach M, et al. The association between daily step count and all-cause and cardiovascular mortality. Eur J Prev Cardiol 2023. DOI
  4. US Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition, 2018. Link
  5. Mandsager K, et al. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Netw Open 2018. DOI
  6. Kokkinos P, et al. Cardiorespiratory fitness and mortality risk across the spectra of age, race, and sex. J Am Coll Cardiol 2022. DOI
  7. Ajufo E, et al. Accelerometer-measured sedentary behavior and cardiovascular outcomes. J Am Coll Cardiol 2025. DOI
  8. Stamatakis E, et al. Vigorous intermittent lifestyle physical activity and mortality in non-exercisers. Nat Med 2022. DOI
  9. Li R, et al. Wearable activity tracker-based interventions among community-dwelling older adults: systematic review and meta-analysis. J Med Internet Res 2025. DOI
  10. Maximidou T, Mons U. Wearable-based cardiac rehabilitation in coronary artery disease: systematic review and meta-analysis. Am J Prev Cardiol 2025. DOI
  11. Au WW, et al. Effect of wearable activity trackers on physical activity in children and adolescents. Lancet Digit Health 2024. DOI