Using Fins for "unloading"
I recently swam next to a fellow who looked very athletic and had a printed-out workout with him and a paddleboard, pull buoys, and hand paddles. He was surprisingly slow in the water, so I watched him to figure out why.
When he wasn't using anything, he had horrible dropped elbows. But when he put the paddles on, he actually had very nice elbows. He took the paddles off and he reverted to his horrible stroke again. Unless he planned to do his "useful" swimming with paddles, they were doing him more harm than good. Kind of drove home the point of how paddles can be counter-productive.
The classical reasons for doing kick drills or pull buoys is to "overload" the muscles. TI has promoted "underloading" to avoid the effect of creating poor mechanics that I just mentioned, and has suggested using Fist Gloves to do that. I actually have a pair of fist gloves, but I have never used them. They seem like a great idea, and I really should try them.
I recently acquired some training fins. These are "hydro" fins from All-American Aquatics. They are similar to the Speedo training fins, but a softer rubber, so they are easier on the ankles.
In using them, I have found them useful for drilling -- maintaining a speed more similar to swimming while drilling. But I have also found an unloading effect on the arms, similar to how fist gloves are supposed to work.
Underloading the arms is a great way to work on proper stroke mechanics. When you get the mechanics right then you can gradually add more force. However, slow swimming, in either drilling or cruising whole stroke, tends to actually load the arms more. Adding the fins in really helps. I was able to work out several timing problems in backstroke and butterfly with the help of the fins.
Fins, however, are very addictive. I think it is very easy to become reliant on them too much, so I only use them for 10 minutes at a time.
I am not using them for "overtraining" the legs, but am using them to "undertrain" the arms. I don't remember anyone really bringing this up (other than using them for maintaining speed while drilling).
I think fist glove training is a good idea too. Like I said I really should try them, too.