Table 3 Description of predictor variables

sba

\(sba_{i} = \frac{1}{7}*\sum\nolimits_{j = i - 3}^{i + 3} {acc_{j} }\)

Static body acceleration

sba_x_c

\(sba\_x\_c_{i} = sba\_x_{i} - correction\_value_{tag}\)

Corrected static body acceleration of x axis

dba

\(dba_{i} = {\left| acc_{i} - {sba_{i} } \right|}\)

Dynamic body acceleration

mdba

\(mdba_{i} = \frac{1}{w}\sum\nolimits_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} { {dba_{i} }}\)

Mean dynamic body acceleration

mdba_xyz

\(mdba\_xyz_{i} = \sum\nolimits_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} {\left( {dba\_x_{j} + dba\_y_{j} + dba\_z_{j} } \right)}\)

Overall mean dynamic body acceleration of the x-, y- and z-axis

meandl

\(meandl_{i} = \frac{1}{w}\sum\nolimits_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} {\left| {acc_{j + 1} - acc_{j} } \right|}\)

Mean absolute difference between adjacent data points

vardl

\(vardl_{i} = \frac{1}{w - 1}\sum\nolimits_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} {\left( {\left| {acc_{j + 1} - acc_{j} } \right| - meandl_{i} } \right)^{2} }\)

Variance of the absolute difference between adjacent data points

varsba

\(varsba_{i} \frac{1}{w - 1}\sum\nolimits_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} {\left( {sba_{j} - \overline{sba} } \right)^{2} }\)

Variance of the static body acceleration

vardba

\(vardba_{i} = \frac{1}{w - 1}\sum\nolimits_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} {\left( {dba_{j} - \overline{dba} } \right)^{2} }\)

Variance of the dynamic body acceleration

maxdba

\({ \hbox{max} }dba_{i} = MAX_{{j = i - \frac{w}{2}}}^{{i + \frac{w}{2}}} \left( {dba_{j} } \right)\)

Maximum of the dynamic body acceleration

dps

See R-Script (Additional file 8).

Dominant power spectrum

fdps

See R-Script (Additional file 8).

Frequency of the dominant power spectrum