The arm bar vs. the double bend forehand:

[GeoffWilliams]

Delpotro, Nadal, Soderling, Fed, Verdasco, all arm bar. Courier, Agassi, and many others such as Nalbandian, are double benders. The arm bar allows greater leverage, due to greater length of the lever arm, on the mass of the ball. So why don't all the pros use the arm bar except for only the ones who hit the ball flattest? Fed hits both types.... I use the double bend, but always wanted more power... I'd like to see some didactic analysis on the comparison....The arm bar fh seems more adapted to improvisational skill, while the double bend seems more stable and less prone to ues....

[spacediver]

The following thoughts are based on a relatively naive working knowledge of physics, so take them as such:

One thing to take into consideration may be the issue of rotational inertia. With an arm bar forehand, the distribution of body mass extends further out into the radius of rotation. It would therefore take more force to rotate the body at a given angular velocity (although there is the positive tradeoff of increased instantaneous speed because of the wider radius).

On the other hand, initiating the rotation with an arm bar forehand, and then bringing the arms into a more bent position while the rotation is underway, may serve to channel that extra effort into increased angular velocity.

There's also the idea of being well braced for a shot. With heavy incoming balls, a bent arm forehand allows a higher concentration of mass to be behind the shot. The discussion of an bent arm vs arm bar forehand may therefore be, at least in this particular aspect, analagous to the discussion of the pros and cons of heavier vs. lighter racquets.

Finally, with a bent arm forehand, the internal rotators of the shoulder can contribute positively towards the stroke, while in the arm bar forehand, it is the chest muscles that achieve the same movement of the racquet through space. Not sure if this is a disadvantage or an advantage, but I do know that the chest muscles have to work significantly harder in the arm bar forehand due to the longer lever (in this case, there is more leverage against the pecs).

[GeoffWilliams]

Well thought out. INteresting comment.