3D Definitions - JohnHellstrom.com
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3D Definitions

Courtesy of Dr. Robert Neal, Golf Biodynamics

Below you can see some of the definitions that is used in the GBD 3D protocols. The protocols has a column to the left with intervals that professional players usually have. Your values are in the column to the right. If your values are in the most common range, then it is free. If it is just outside, then it is yellow. If your values are far away, then they are red. The colours only indicates that it is more or less common and needs to be discussed, it does not mean that it is bad or good.

WAR – within the acceptable range
TOB – Top of the Backswing
ROM – Range of Motion

 

Pelvis (hip) Rotn (deg)
The amount of rotation of the hips about the spine. When standing square to the target, the value is 0. As you turn away on the backswing the hips close (~45 degrees maximum). The hips open during the downswing

Upper torso (shoulder) Rotn (deg)
The amount of rotation of the shoulders about the spine. When standing square to the target, the value is 0 degrees. As you turn away on the backswing the shoulders close. They then open during the downswing

X Factor (deg)
The relative rotation between the hips and shoulders. For example, if the hips rotate 40 degrees and the shoulders rotate 90 degrees, the X Factor equals 50 degrees

Pelvis (hip) Bend (deg)
Bending is forward/backward rotation. Thus hip bend is the amount of flexion (forward bend) or extension (backward bend) of the pelvis. This angle is measured from a horizontal line (level ground).

Upper torso (shoulder) Bend (deg)
Shoulder bend is the amount of flexion (forward bend) or extension (backward bend) of the section of the back near your shoulder blades (representing the upper torso or both shoulders). This angle is measured from a horizontal line (level ground).

Spine Bend (deg)
The relative bending between the shoulders and hips is spine bend. It gives an indication of whether the back is extended or flexed. In your normal standing position, spine bend is 0 degrees.

Pelvis (hip) Tilt (deg)
This angle is the sideways tilting (lateral bending) of the hips and is measured from a horizontal line (level ground).

Upper torso (shoulder) Tilt (deg)
This angle is the sideways tilting of the shoulders and is measured from a horizontal line (level ground). This tilting is also referred to as lateral bending, with R to the right and L to the left of your normal, upright standing posture.

Spine Tilt (deg)
The relative tilting between the shoulders and hips is spine tilt. It gives an indication of whether the back is laterally bent to the right or the left. In your normal standing position, spine is 0 degrees.

Head Rotn (deg)
Head rotation is defined as the amount of axial rotation about the spine. When standing upright and facing forward, head rotation angle is zero degrees. Looking right is closed while looking left is open.

Head Bend (deg)
Head bend is forward and backward rotation of the head. Bending (flexion) is measured from the horizontal. Thus, with the head upright the angle would be 90 degrees, whilst looking down (face parallel to the ground) is 0 degrees.

Head Tilt (deg)
Head tilt measures the sideways (lateral) tilting of the head relative to the horizontal. With the head straight, the angle is 0 and from this position the head can tilt to the right (R) or left (L).

Pelvic (hip) Rotn Spd (deg/s)
Hip rotation speed is the component of angular velocity of the hips about the spine. It does not include the components due to tilting and bending. It represents how fast the hips are rotating about the long axis of the spine.

Upper torso (shoulder) Rotn Spd (deg/s)
Shoulder rotation speed is the component of angular velocity of the shoulders about the spine. It does not include the components due to tilting and bending. It represents how fast the shoulders are rotating about the long axis of the spine.

Hand Speed (cm/s)
The speed of the hands is calculated as d(RH)/dt. RH = rX + rY + rZ (the displacement of the sensor on the hand measured in the global coordinate system). It represents how fast the hands are moving.

Pelvic (hip) Sway (cm)
Hip sway is the sideways (lateral) motion of the hips. It is measured as a distance relative to the transmitter. Typically a right-handed golfer moves the hips to his/her right (away from the target) during the backswing and then to the left (toward the target) during the downswing.

Upper torso (shoulder) Sway (cm)
Shoulder sway is the sideways (lateral) motion of the shoulders. It is measured as a distance relative to the transmitter. Typically a right-handed golfer moves the shoulders to his/her right (away from the target) during the backswing and then to the left (toward the target) during the downswing.

Head Sway (cm)
Head sway is the sideways (lateral) motion of the head. It is measured as a distance relative to the transmitter. Typically a right-handed golfer moves the head to his/her right (away from the target) during the backswing and then to the left (toward the target) during the downswing.

Hand Sway (cm)
Hand sway is the sideways (lateral) motion of the hand. It is measured as a distance relative to the transmitter. Typically a right-handed golfer moves the hands to his/her right (away from the target) during the early part of the backswing and then to the left (toward the target) after the hands reach hip level. During the downswing they first move away from the target and then rapidly toward the target.

Pelvic (hip) Thrust (cm)
Hip thrust is the forward/backward motion of the hips. It is measured as a distance relative to the transmitter. Increasing numbers mean that the hips are getting closer to the ball while decreasing values indicate movement away from the ball.

Upper torso (shoulder) Thrust (cm)
Shoulder thrust is the forward/backward motion of the shoulders. It is measured as a distance relative to the transmitter. Increasing numbers mean that the shoulders are getting closer to the ball while decreasing values indicate movement away from the ball.

Head Thrust (cm)
Head thrust is the forward/backward motion of the head. It is measured as a distance relative to the transmitter. Increasing numbers mean that the head is getting closer to the ball while decreasing values indicate movement away from the ball.

Hand Thrust (cm)
Hand thrust is the forward/backward motion of the hands. It is measured as a distance relative to the transmitter. Increasing numbers mean that the hands are getting closer to the ball while decreasing values indicate movement away from the ball.

Pelvic (hip) Lift (cm)
Hip lift is the vertical (up/down) movement of the hips. These movements are measured relative to the height of the transmitter. Increasing values are indicative of upward motion whilst decreasing numbers show downward movement.

Upper torso (shoulder) Lift (cm)
Shoulder lift is the vertical (up/down) movement of the shoulders. These movements are measured relative to the height of the transmitter. Increasing values are indicative of upward motion whilst decreasing numbers show downward movement.

Head Lift (cm)
Head lift is the vertical (up/down) movement of the head. These movements are measured relative to the height of the transmitter. Increasing values are indicative of upward motion whilst decreasing numbers show downward movement.

Hand Lift (cm)
Hand lift is the vertical (up/down) movement of the hands. These movements are measured relative to the height of the transmitter. Increasing values are indicative of upward motion whilst decreasing numbers show downward movement.

Arc Width (cm)
Arc width is the distance between the sensor on the hands and the one in between the shoulder blades. When the numbers for this parameter decrease, the hands are getting closer to the shoulders and increasing values mean that the hands are moving further away from the shoulders.

 Please note: all measurements are in centimetres (cms), degrees, or degrees/sec.