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The wrong chart

The number that may say more than your weight, and how to read your own · 14 min

In 1992, almost six thousand Chicago women walked a treadmill as far as they could. Years later, cardiologist Martha Gulati found they had been judged on a chart built from men. The number that may say more about your future health than the scale, why the formula on the gym wall was only drawn to look about right, and a free way to read your own.

Takeaways

  • In a Chicago study of nearly 6,000 women, those whose treadmill result was below 85% of the expected level for their age had about twice the risk of death; the chart doctors had used was built from men.
  • The '220 minus your age' heart-rate formula was a line drawn to fit about eleven earlier studies, with no equation fitted; for one person it can be about 20 beats a minute off.
  • In large observational studies, fitness went with survival more strongly than weight did. This month: one route, one talk check at the top, once a week, compared only with yourself.

Chapters

  1. The wrong chart0:17
  2. The line on the gym wall2:21
  3. The number that matters4:00
  4. Two ways to read it6:56
  5. Hear it done8:34
  6. Build yours9:52
  7. The answer11:55

References

  1. Gulati, M., Black, H. R., Shaw, L. J., et al. — The prognostic value of a nomogram for exercise capacity in women(2005)
  2. Rush University Medical Center (EurekAlert) — Study of 5700 women finds not enough exercise means serious risk for heart problems, death(2005)
  3. Gulati, M., Shaw, L. J., Thisted, R. A., et al. — Heart rate response to exercise stress testing in asymptomatic women: the St. James Women Take Heart Project(2010)
  4. Robergs, R. A., & Landwehr, R. — The surprising history of the "HRmax=220-age" equation(2002)
  5. Kodama, S., Saito, K., Tanaka, S., et al. — Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis(2009)
  6. Mandsager, K., Harb, S., Cremer, P., Phelan, D., Nissen, S. E., & Jaber, W. — Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing(2018)
  7. Weeldreyer, N. R., De Guzman, J. C., Paterson, C., Allen, J. D., Gaesser, G. A., & Angadi, S. S. — Cardiorespiratory fitness, body mass index and mortality: a systematic review and meta-analysis(2025)
  8. Barry, V. W., Baruth, M., Beets, M. W., Durstine, J. L., Liu, J., & Blair, S. N. — Fitness vs. fatness on all-cause mortality: a meta-analysis(2014)
  9. Ross, R., Blair, S. N., Arena, R., et al. — Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign(2016)
  10. Lambe, R., et al. — Investigating the accuracy of Apple Watch VO2 max measurements: a validation study(2025)
  11. Jenkins, E. M., Nairn, L. N., Skelly, L. E., Little, J. P., & Gibala, M. J. — Do stair climbing exercise "snacks" improve cardiorespiratory fitness?(2019)