Schwendinger F; (University of Basel, Basel, SWITZERLAND.)
Wagner J; Knaier R; Infanger D; Rowlands AV;Hinrichs T; Schmidt-Trucksäss A;

Medicine and science in sports and exercise [Med Sci Sports Exerc] 2023 Sep 13.
Date of Electronic Publication: 2023 Sep 13.

Purpose: Accelerometer-assessed physical activity (PA) can be summarised using cut-point-free or population-specific cut-point-based outcomes. We aimed to: 1) examine the interrelationship between cut-point-free (intensity gradient [IG] and average acceleration [AvAcc]) and cut-point-based accelerometer metrics, 2) compare the association between cardiorespiratory fitness (CRF) and cut-point-free metrics to that with cut-point-based metrics in healthy adults aged 20 to 89 years and patients with heart failure, and 3) provide age-, sex-, and CRF-related reference values for healthy adults.
Methods: In the COmPLETE study, 463 healthy adults and 67 patients with heart failure wore GENEActiv accelerometers on their non-dominant wrist and underwent cardiopulmonary exercise testing. Cut-point-free (IG: distribution of intensity of activity across the day; AvAcc: proxy of volume of activity) and traditional (moderate-to-vigorous and vigorous activity) metrics were generated. The ‘interpretablePA’ R-package was developed to translate findings into clinical practice.
Results: IG and AvAcc yield complementary information on PA with both IG (p = 0.009) and AvAcc (p < 0.001) independently associated with CRF in healthy individuals (adjusted R2 = 73.9%). Only IG was independently associated with CRF in patients with heart failure (p = 0.043, adjusted R2 = 38.4%). The best cut-point-free and cut-point-based model had similar predictive value for CRF in both cohorts. We produced age- and sex-specific reference values and percentile curves for IG, AvAcc, moderate-to-vigorous PA, and vigorous PA for healthy adults.
Conclusions: IG and AvAcc are strongly associated with CRF and, thus, indirectly with the risk of non-communicable diseases and mortality, in healthy adults and patients with heart failure. However, unlike cut-point-based metrics, IG and AvAcc are comparable across populations. Our reference values provide a healthy age- and sex-specific comparison that may enhance the translation and utility of cut-point-free metrics in clinical practice.
Competing Interests: Conflict of Interest and Funding Source: The COmPLETE study was funded by the Swiss National Science Foundation (Grant no. 182815). AVR is supported by the Lifestyle Theme of the Leicester NHR Leicester Biomedical Research Centre and NIHR Applied Research Collaborations East Midlands (ARC-EM). The authors declare that they have no competing interests. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by the American College of Sports Medicine.