This is the source of a common misconception but the point of interest is just used to break down a complex motion to simple but meaningful linear and angular motion elements.Īnother example of a complex motion commonly broken down to meaningful linear and angular motion elements is the pelvis motion (Figure 4). It is important here to understand that the point of interest used in breaking down the club motion doesn't have to be a fixed physical center of rotation. The blue dots are the positions of club's COM at various downswing events and the blue line is the trajectory of the COM. Motion of the club during the downswing in the COM perspective.

This COM perspective is commonly used in Newtonian mechanics.įigure 3. If you are interested in the stand-alone motion of the club (without considering the hand-club interaction), club's center of mass (COM) may be used as the point of interest (Figure 3). In the example above, the mid-hand point was used as the point of interest and the club motion was broken down to linear motion of the mid-hand point and angular motion of the club about the mid-hand point. Selection of the representative point depends on the interest of the investigator. Simple motions of the club during the downswing: linear motion of the mid-hand point (A) and angular motion of the club about the mid-hand point (B). Actually, since linear motion and angular motion are very different in nature, these must be separated for an in-depth analysis.įigure 2. It is easier to handle these simple motions separately than the actual complex motion at once. This is actually a common practice in biomechanics to break down a complex motion to linear motion of a point on the object and angular motion of the object about the point. In this case, the mid-hand point was selected as the representative point of the club as the focus is how the hands guide the club and how the club rotates around the hands. This club motion can then be broken down to two simple motions: linear motion of the mid-hand point (Figure 2A) and angular motion of the club about the mid-hand (Figure 2B). The red dots are the positions of the mid-hand point at various downswing events and the blue line is the trajectory of the mid-hand.

The mid-hand point, mid-point of the hand centers, moves along a curved path (curvilinear motion) with varying curvature while the club also rotates about the mid-hand point.įigure 1. Linear motion can also be viewed as motion of a point and have two types: rectilinear (straight path) and curvilinear (curved path).įigure 1 shows the motion of a club (driver) during downswing observed in the functional swing plane. Linear motion is translation from one position to another while angular motion is rotation about an axis or center of rotation. Angular MotionĪny complex motion of a body can be broken down to two simple motions: linear motion and angular motion.

Angular motion