Is the clasped-hand strike seen in Star Trek part of a real/fictional martial art?

I'm less familiar with Enterprise and Voyager, but in TOS, TNG, and DS9 I have repeatedly seen Star Fleet officers engaged in melee combat perform this awkward and slow-looking attack where they clasp both hands together and swing at their opponent. At times it looks like they are trying to chop wood with no axe, hitting the opponent from the side. Other times, it looks like they are playing volleyball extra vigorously, uppercutting their enemy with both hands.

If this were just in TOS, I would assume it was just the choreography of the day. However, it is still present in the more modern incarnations of the show. Is this part of a fictional martial art that is used by Star Fleet (and possibly others? I can't recall if, for example, I have ever seen klingons use this technique), or is it part of a real martial art? If there is no canon explanation (i.e. this move is not part of either a real or a fictional martial art), then why did they continue to use such awkward choreography in the more modern series?

Answer

I believe the maneuver you are referring to is the Double Axe Handle Strike. While in professional wrestling it's typically done as a jumping or falling move it can be done, as in Star Trek, while standing or running. As you've pointed out it's not very practical in real combat, it's highly telegraphed, and easily avoided. Also, lacing your fingers together in that fashion will almost undoubtedly do more damage to your own hands than your opponent.

I believe the out of universe reason is that the more bombastic a fight scene was depicted the more the public would enjoy it. While Star Trek has always had social commentary at its core, it is still a television show dependent on ratings. During TOS era the American public's exposure to martial arts was predominantly limited to Kung Fu movies. As exposure to more "realistic" fighting styles became prevalent TV fights became more "realistic" as well. Trek being a franchise with a hardcore fan base held on to some aspects of TOS all through its run, either for nostalgia or kitsch, which is why you still see the fighting move in TNG and other Trek series.