It is interesting that Homer said the Swinger's Clubshaft is also stressed, but during the change of direction at Start Down.
In a 1981 GSEM Class discussion, Homer Kelley referred to two types of Clubshaft Bend for Swingers. The first -- "Acceleration Bend" -- stresses the top of the Shaft during the Start Down. During the second -- "Release Bend" -- the stress is opposite the Acceleration Bend as the toe of the Club attempts to get in line with the #3 Pressure Point.
The Hitter's stress is at the back of the Shaft and does not vary.