Table 1.

Extracted motion features and physical meaning.

Number	Feature	Definition	Physical meaning
1	AMPa	AMP=max(x) – max(x)	Describes the magnitude of the movement
2	MEANb		Describes the direction of the movement
3	RMSc		Describes motion dynamic energy
4	JERK		Describes motion smoothness
5	Strength	Value	Describes the magnitude of the exercise effort

^aAMP: amplitude.

^bMEAN: mean value.

^cRMS: root-mean-square.