Wrist acceleration cut points for moderate-to-vigorous physical activity in youth

Okely, Anthony D. and Batterham, Marijka J. and Hinkley, Trina and Ekelund, Ulf and Brage, Søren and Reilly, John J. and Trost, Stewart G. and Jones, Rachel A. and Janssen, Xanne and Cliff, Dylan P. and Van Loo, Christiana Maria Theodora (2018) Wrist acceleration cut points for moderate-to-vigorous physical activity in youth. Medicine and Science in Sports and Exercise, 50 (3). pp. 609-616. ISSN 0195-9131

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    Abstract

    Purpose This study aimed to examine the validity of wrist acceleration cut points for classifying moderate (MPA), vigorous (VPA), and moderate-to-vigorous (MVPA) physical activity. Methods Fifty-seven children (5-12 yr) completed 15 semistructured activities. Three sets of wrist cut points (>192 mg, >250 mg, and >314 mg), previously developed using Euclidian norm minus one (ENMO 192+), GENEActiv software (GENEA 250+), and band-pass filter followed by Euclidian norm (BFEN 314+), were evaluated against indirect calorimetry. Analyses included classification accuracy, equivalence testing, and Bland-Altman procedures. Results All cut points classified MPA, VPA, and MVPA with substantial accuracy (ENMO 192+: κ = 0.72 [95% confidence interval = 0.72-0.73], MVPA: area under the receiver operating characteristic curve (ROC-AUC) = 0.85 [0.85-0.86]; GENEA 250+: κ = 0.75 [0.74-0.76], MVPA: ROC-AUC = 0.85 [0.85-0.86]; BFEN 314+: κ = 0.73 [0.72-0.74], MVPA: ROC-AUC = 0.86 [0.86-0.87]). BFEN 314+ misclassified 19.7% non-MVPA epochs as MPA, whereas ENMO 192+ and GENEA 250+ misclassified 32.6% and 26.5% of MPA epochs as non-MVPA, respectively. Group estimates of MPA time were equivalent (P < 0.01) to indirect calorimetry for the BFEN 314+ MPA cut point (mean bias = -1.5%, limits of agreement [LoA] = -57.5% to 60.6%), whereas estimates of MVPA time were equivalent (P < 0.01) to indirect calorimetry for the ENMO 192+ (mean bias = -1.1%, LoA = -53.7% to 55.9%) and GENEA 250+ (mean bias = 2.2%, LoA = -56.5% to 52.2%) cut points. Individual variability (LoA) was large for MPA (min: BFEN 314+, -60.6% to 57.5%; max: GENEA 250+, -42.0% to 104.1%), VPA (min: BFEN 314+, -238.9% to 54.6%; max: ENMO 192+, -244.5% to 127.4%), and MVPA (min: ENMO 192+, -53.7% to 55.0%; max: BFEN 314+, -83.9% to 25.3%). Conclusion Wrist acceleration cut points misclassified a considerable proportion of non-MVPA and MVPA. Group-level estimates of MVPA were acceptable; however, error for individual-level prediction was larger.