A 3-minute test of cardiorespiratory fitness for use in primary care clinics

PLoS One. 2018 Jul 30;13(7):e0201598. doi: 10.1371/journal.pone.0201598. eCollection 2018.


Background: Cardiorespiratory fitness (CRF) is the only major risk factor that is not routinely assessed in the clinical setting, for preventive medicine. A valid and practical CRF test is needed for use in the clinics. The objective of this study is to demonstrate the validity of a 3-minute squat test to assess CRF in primary care.

Methods: A cross-sectional study in which the participants performed both the Ruffier squat test and the Balke maximal treadmill test. The study was conducted in a clinical setting from September 2016 to March 2017. We recruited a convenient sample of 40 adults between 18 and 64 years from the general U.S. population. Participants completed 30 squats in 45 seconds, paced by a metronome. Heart rate was measured at rest (P1), immediately after the test (P2), one minute after the test (P3). [Formula: see text] was measured using the Balke maximal treadmill fitness test.

Results: Of the 40 participants, there were 18 men and 22 women. Mean age was 31.2 years (SD = 9.9). We found that the best [Formula: see text] predictors were HR features P1/height and (P2-P3)/age3. Our best-performing model using these two features predicted individuals' CRF levels with an adjusted R2 of 0.637, sensitivity of 0.79, and specificity of 0.56.

Conclusions: The study provided strong evidence for the validity of the squat test in the clinical setting. Further, the equation of our model along with [Formula: see text] normative tables provides an efficient and easy way to assess CRF in a primary care setting.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Ambulatory Care Facilities
  • Cardiorespiratory Fitness / physiology*
  • Cross-Sectional Studies
  • Exercise Test / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Oxygen Consumption / physiology
  • Physical Fitness / physiology
  • Primary Health Care / methods*
  • Time Factors
  • Young Adult