To accomplish the goals of this study, thirty amateur male golfers were tested. These subjects were recruited as a population of average male amateur golfers in the United States using demographics provided by the National Golf Foundation and the United States Golf Association. In order to participate the male golfer subject met specific age and handicap criterion. The age range was thirty to fifty years old. The handicap range was ten to thirty. The thirty golfers were randomly separated into three groups: a control, static stretch and 'machine assisted' passive stretch.
The 'machine assisted' passive stretching routine consisted of a series of ten settees performed on the BackSystem3. Each stretch was performed for a total of five repetitions.
-
01. low back and hips
02. upper back and shoulders
03. groin and adductor
04. hamstring
05. gluteals and piriformis
06. rotational torso, hamstring, IT band
07. latissimus dorsi
08. shoulder and neck complex
09. quadratus
10. quadriceps
The static stetching routine consisted of a series of ten stetches. Each stretch was performed for one repetition. Each repetition was held for 10 seconds.
-
01. lower back
02. upper back
03. adductors
04. achilles tendon and posterior lower leg
05. buttocks and hip 1
06. buttocks and hip 2
07. lateral shoulder
08. shoulder internal/external rotators 1
09. shoulder internal/external rotators 2
10. quadriceps
The two stretching routines were designed to be analogous in purpose and in scope. They were designed to starch the same muscles in an equivalent progression.
Golf swing data caulk ion was accomplished using a video based, three-dimensional motion capture system (Peak Performance Peak5 System). The swing movement was captured using standard video cameras (Panasonic AG350). The cameras were strategically placed in positions that would allow the full body and all of the joints necessary for digitization to be viewed throughout the movement of the golf swing. Both cameras filmed during the entire testing procedure.
Once data was collected, the video tapes were encoded by the Peak5 system prior to the digitizing process. Encoding is a process by which the capture system marks each frame of video allowing the frame grabber hardware to systematically retrieve frames of an activity in proper sequence. When the tapes had been encoded, swings from each test where digitized to create three-dimensional data from the two-dimensional video image. The two video cameras were synchronized during the digitizing process using the common event of impact as the point of reference. If the point of impact was not captured then the first frame after impact was used.
The same points on each subject were digitized for each trial processed. These points were:
-
1. left shoulder
2. right shoulder
3. left elbow
4. right elbow
5. left wrist
6. right wrist
7. left hip
8. right hip
9. top of the club grip
10. bottom of the club grip
The first step in the digitizing process is to create a two-dimensional numeric representation of the video image for a given trial. This was done for each of the two camera views. This data was then filtered using a cubic spline to eliminate any severe erratications that may have occurred during the digitizing process. Once each of the files was filtered they were then used to create the three-dimensional information. The raw three-dimensional information was then filtered using a Butterworth filter with a cutoff frequency of 10 Hz.
Using the technique of applying kinetic linking principles to the swing motion described by Welch et al (Hitting a Baseball: A Biomechanical Description), specific parameters were defined to measure both biomechanics skills and power generation. These parameters were:
-
1. hip segment rotation
2. shoulder segment rotation
3. arms segment rotation
4. hip segment angular speed
5. shoulder segment angular speed
6. arms segment angular speed
7. club release (lag angle) angular speed
8. core energy transfer
The hip segment was defined as a vector pointing from the right hip to the left hip. The shoulder segment was defined as a vector pointing from the right shoulder to the left shoulder. The arms segment was defined as a vector pointing from mid-shoulder segment to a point between the two wrists. The club shaft was represented by the unit vector created using the points at the top and bottom of the club grip. Rotation and represented by the unit vector created using the points at the top and bottom of the club grip. Rotation and angular speed were defined as displacement and the first derivative of displacement, respectively, around a common axis with respect to the global reference frame. Core energy transfer was defined as the ratio between the shoulder segment peak angular speed and the hip segment peak angular speed.
