View Full Version : The X Factor

Aguinaldo, Arnel
08-19-2003, 04:13 AM

I am trying to locate an article written by Mike McTeigue et al. (1994) on
the golf swing's X-Factor. All my pubmed, sports lit, and google searches
have come up short. I know he's written some articles for Golf Magazine, but
I believe he's also conducted a study on the X-Factors of PGA hitters.

For those of you who study or play golf, is the "X-Factor" simply, in
clinical terms, upper trunk rotation measured relative to pelvic rotation
(ie, shoulders turn - hips turn)? From what I've read so far, highly-skilled
players have larger X-Factors than those of less-skilled players and,
subsequently, generate more potential energy (elastic) during the backswing
that is transferred to the downswing for higher club speeds at impact. In
other words, the wider the separation between the trunk and the pelvis, the
more potential for trunk rotation during the downswing. However, shouldn't
the timing of this rotation be important (if not more) as well? What we
found in our pitching analyses is that the hip-shoulder separations of
pro-level pitchers do not differ significantly from those of less-skilled
ones, but the timing in which this separation begins to narrow does. The
pro-pitchers seem to narrow this gap a lot later in the pitch and thus
generate more angular velocity into ball release. Perhaps this same
phenomenon occurs in a golf swing although I have yet to verify this as we
haven't analyzed many golfers yet. It would seem that the longer golfers can
keep this so-called X-Factor constant (or even increasing), the faster the
club will be towards the end of downswing. What are your takes on this?

Thanks in advance for your comments.


Arnel Aguinaldo, MA, ATC
Motion Analysis Laboratory & Center for Human Performance
Children's Hospital San Diego | San Diego, CA USA
(858) 966-5807 | www.sandiegogaitlab.com

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