Validity of traditional physical activity intensity calibration methods and the feasibility of self-paced walking and running on individualised calibration of physical activity intensity in children

Eero A Haapala,Ying Gao,Anssi Vanhala,Taija Finni,Timo Rantalainen

doi:10.1038/s41598-020-67983-7

Abstract

There are no practical and valid methods for the assessment of individualised physical activity (PA) intensity in observational studies. Therefore, we investigated the validity of commonly used metabolic equivalent of tasks (METs) and pre-determined PA intensity classification methods against individualised PA intensity classification in 35 children 7–11-years-of-age. Then, we studied validity of mean amplitude deviation (MAD) measured by accelerometry during self-paced walking and running in assessment of individualised PA intensity. Individualised moderate PA (MPA) was defined as V̇O2 ≥ 40% of V̇O2reserve and V̇O2 < ventilatory threshold (VT) and vigorous PA (VPA) as V̇O2 ≥ VT. We classified > 3–6 (or alternatively > 4–7) METs as MPA and > 6 (> 7) METs as VPA. Task intensities were classified according to previous calibration studies. MET-categories correctly identified 25.9–83.3% of light PA, 85.9–90.3% of MPA, and 56.7–82.2% of VPA. Task-specific categories correctly classified 53.7% of light PA, 90.6% of MPA, and 57.8% of VPA. MAD during self-paced walking discriminated MVPA from light PA (sensitivity = 67.4, specificity = 88.0) and MAD during self-paced running discriminated VPA from MPA (sensitivity = 78.8, specificity = 79.3). In conclusion, commonly used methods may misclassify PA intensity in children. MAD during self-paced running may provide a novel and practical method for determining individualised VPA intensity in children.

Highlights

There are no practical and valid methods for the assessment of individualised physical activity (PA) intensity in observational studies
We found that defining PA intensity using fixed metabolic equivalent of tasks (METs) and task-specific classification methods may lead to large errors in the classification of individualised PA intensity in children
We found that mean amplitude deviation (MAD) values measured during different laboratory activities normalised to MAD values measured during self-paced running had acceptable sensitivity to discriminate individualised vigorous PA (VPA) from moderate PA (MPA)

Summary

Introduction

There are no practical and valid methods for the assessment of individualised physical activity (PA) intensity in observational studies. Previous studies have used fixed acceleration magnitude cut-offs to define different PA intensities without accounting for individual variation in exercise c apacity[6]. Previous calibration studies in children have provided several different cut-offs for light (LPA), moderate (MPA), and vigorous PA (VPA) leading to a large variation in the proportion of children meeting the PA r ecommendations[7,11,12]. Some evidence suggests that of fixed acceleration magnitude cut-offs, those provided by Evenson et al.[13] and Freedson et al.[14] may be the most suitable for estimating PA intensity in children[15] These studies have subjectively decided calibration task intensities to determine LPA, MPA, and VPA irrespective of their true metabolic c ost[7,11,12].

Methods

Results

Conclusion