Posted by: Jack Mankin (MrBatspeed@aol.com) on Wed Jul 26 22:01:52 2000

>>>It is not necessary to subscribe to linear mechanics to accept that the kinetic chain is at work. It is involved in virtually all high-speed sporting events from the pole vault, to throwing, to golf, etc. It is merely the sequential contraction of progressively smaller muscles. Here is the absract of a study which shows the sequence I'm referring to:
>
> Clin Orthop 1993 Jul;(292):285-93
> Related Articles, Books
>
> Baseball batting. An electromyographic study.
>
> Shaffer B, Jobe FW, Pink M, Perry J
>
> Department of Orthopaedics, Georgetown Medical Center, Washington, D.C.
>
> The muscle firing pattern in 12 muscles throughout the lower extremity, trunk, and upper extremity during the
> batting swing is described in this study. The two hamstring muscles studied and the gluteal muscle had a similar
> pattern of high muscle activity during pre-swing and early swing, and then rapidly diminished. The vastus medialis
> demonstrated peak activity between 95 and 110% maximum muscle test (MMT) throughout the swing phases and
> follow-through. The erector spinae demonstrated activity from 85 to 185% MMT during the swing phases. The
> abdominal obliques showed greater than 100% MMT during the swing phases and follow-through. The
> supraspinatus and serratus anterior showed relatively low muscle activity (less than 40% MMT). These results
> show that batting is a sequence of coordinated muscle activity, beginning with the hip, followed by the trunk, and
> terminating with the arms. Power in the swing is initiated in the hip, and therefore exercises that emphasize such
> strength development are indicated. The maintained, high muscle activity in the trunk muscles indicates a need for
> back and abdominal stabilization and rotation exercises. The relatively low level of activity in the four
> scapulohumeral muscles tested indicated that emphasis should be placed on the trunk and hip muscles for a
> batter's strengthening program.<<<

Hi Steve

Great reading Steve, but I think it would be more helpful to the coaches and players if you would explain how the kinetic chain is involved in the baseball/softball swing. --What mechanics does it employ to accelerate the bat? -- If the kinetic chain is sequential in nature, are only the muscle groups of the lower body contracting at swing initiation? -- Are the muscles of the upper body at rest or half speed at initiation? Which small muscles are being accelerated and why. --- Your help would be appreciated.

Jack Mankin