Description

Equations to predict oxygen consumption (mL/kg/min) and activity intensity cut-points for mean amplitude deviation (MAD) were determined from adults wearing a hip-worn monitor while walking and running. Sensitivity (96-100%) and specificity (95-96%) are reported for the cut-points. Correlation coefficients for the prediction models were 0.958 (overall), 0.943 (walking), and 0.975 (with ancillary demographic information).

Development/Validation

Sample: 29 (15 males) healthy adults, 35±11 years of age

Setting: Indoor track

Activities: Overground walking and running

Criterion: Oxycon (VO₂)

Accelerometer(s): Hookie AM13 on left or right hip and middle back

Validation approach: Comparison to criterion

Phase Designation

(What's this?)

This model is in Phase 2.

Instructions

Calculate MAD (mg) as the mean distance of data points about the mean where N is the number of samples in the epoch and j is the start of the epoch, ri is the ith resultant sample within the epoch and R_ave is the mean resultant value of the epoch. This can also be done in R using a package like acc or GGIR. In this paper, they used an epoch of 6 s.

Three equations are presented for predicting oxygen consumption (mL/kg/min), an overall equation with only MAD as an input, a walking-specific equation with MAD as the input, and an overall equation with additional demographic input variables of height (cm), weight (kg), waist circumference (cm), age (years), VO₂peak (ml/kg/min), and the mean speed during the final two minutes of a graded exercise test to volitional exhaustion (vmax in m/s). Each epoch can also be classified as a specific activity intensity using the cut-points, which were 91 mg and 414 mg for 3 and 6 METs, respectively.

VO₂ (mL/kg/min) = 10.015 * e^0.0017*MAD

Walking VO₂ (mL/kg/min) = 7.920 + 0.0331*MAD

VO2 (mL/kg/min) = 2.351*e^{(0.00177*MAD-0.282*vmax+0.0183*VO}₂^{peak+0.0117*height-0.0142*weight+0.00693*waist circumference-0.00211*age)}

Source Information

Vähä-Ypyä, H., Vasankari, T., Husu, P., Mänttäri, A., Vuorimaa, T., Suni, J., & Sievänen, H. (2015). Validation of cut-points for evaluating the intensity of physical activity with accelerometry-based mean amplitude deviation (MAD). PloS One, 10(8), e0134813.

https://doi.org/10.1371/journal.pone.0134813 Link to Paper

Corresponding author: Henri Vähä‐Ypyä, henri.vaha-ypya@uta.fi

Contact

Kimberly Clevenger at accelerometerrepository@gmail.com