Posture is characterized by measuring the angular relationship between various body links and a fixed frame of reference, usually another intuitive major body segment. The unit of measurement is primarily degrees of the angle, but sometimes descriptive terms are used, i.e. “bent 1/2 of way.” Identifying the duration of the specific postures is also important.

Posture can be measured precisely using video and software-based methods. However, for most practical purposes, visual estimates in a broad, intuitive range is sufficient. Simple checklists can be used and/or the posture estimates converted to a scoring system.

The following are standard demarcations between different postures. Motions and positions held within ±15°–20° of the optimal position are generally acceptable. Human performance deteriorates with the increase in angle, probably exponentially.

Lower back

Bending: Angle of torso relative to the upper legs Applies equally to lateral and backward bending		Twisting: Angle of shoulders relative to the hips

Neck

Bending: Angle of head relative to torso Applies equally to lateral and backward bending		Twisting: Angle of head relative to shoulders

Arm

Raising arms Angle of upper arm to torso	Lateral arm orientation Also angle of upper arm to torso Optimal arm position is 15°, not 0°

Wrist and hand

Bending Angle of hand relative to the forearm Applies to any direction	“Ulnar” bend (Common concern) Away from thumb, towards ulnar forearm bone