Hi everyone!
So I have a question about using fins. I have never used them before. However, I have notice people using them alot in the pool where I swim now and have seen people posting about using then in the swimming forum What's the purpose? To help with speed or technique or both? And how do the sizes work?

Thanks!! :-)

Fins can be useful for several reasons or they can be not so useful for several other reasons...

1) If you have a weak kick, fins help strengthen it.
2) If you have trouble with your feet dragging when you swim (thus ruining your body position), fins can help you get past that.
3) Fins are great for building leg muscles because they are so much fun to use and you will kick more.
4) If you bend your knees too much when kicking, fins help you get a feel for how much more efficient kicking from the hip is than kicking from the knee.
5) Fins help make the kick strong enough for folks to do butterfly who can't without them.

There are probably a dozen more uses...

On the down side...
1) If you are training for anything that involves swimming (swim meet, triathlon, open water, etc.) or you plan to swim a lot outside of your pool workouts for other reasons (fun at the lake, whatever), you do not want to become dependent on the fins. This could be disastrous when you find yourself swimming without them.
2) You don't want to use fins for more than one-third of your workouts (see number 1 and some subsequent items below).
3) There are a lot of different types of fins that will affect your kick in different ways. Not all fins serve the same purpose(s).
4) If you have ANY leg/joint injuries, fins can make them worse (this is the number one reason I do not use fins any more - however, I miss them!). If you have had any knee/ankle/foot/hip problem, you may make it worse. If you have a tendency to get cramps (say in the calf?) then you might get them more frequently using fins.
5) Overuse of fins can mess up your (body/arm) stroke technique or weaken it over time.

So, you want to balance any use of fins with other sorts of working out in the pool (regular swimming, pulls only, drills, etc.).

As for sizing they are usually sized similarly to shoe sizes but with a wider range (like 7-9 and such).

The shorter the fin usually the stiffer. The stiffer they are usually the more stress on any joints that already have issues. If your legs are fine and you have no joint issues, you don't need to worry too much about this as long as you aren't doing whole workouts in fins for long periods. The different lengths/stiffnesses will feel different while you kick. Shorter is more powerful (in a sprinty way).

I used to love fins so I am not bashing them. However, I have had a few too many leg joint injuries (including one knee surgery) to use them not. Fins did not cause these injuries, of course, but they aggravate their healing.

Most pools will have a bin of pool fins (that belong to the pool) that you can try out. I suggest doings first or trying out fins of friends (who have similar sized feet to you) to see how you like them.

I used fins yesterday. Am doing the swim speed secrets programme and the workout included 1000m kick with fins. Boy do my glutes feel it today -I have done lengthy kick sets before without fins and don't usually feel it.

Swim smooth seems to recommend for drills, TI is against anything like that not my bag at all. I think there is a big issue that if your stroke is not perfect they can cause more problems

Last night I was shooting for 5km using the Burners only for 12 kick board laps out of the 110. No find for 98 laps.
At 100 laps the lifeguard had to close the pool due to lightning. Damn!
At least I found out I do have the upper body endurance to do the 5K without fins.
This thread got me to think about that.
Also checked out some of the coaching vids on Speedo pace club. Pretty cool. I'm going to have to try some of those drills.

I get a better "feel" for the water with fins, the impact of my movements are amplified (obviously sine I move faster) and I discover what difference a better/longer stretch can do, how I really need to relax my hands and wrists to not cause unnecessary resistance - and so on. And for strength drills... brilliant.

The best use has been to incrase my ankles flexibility and this happened when I recently changed fins, from the typical short training fin to a somewhat longer and certainly more flexible. The blade forces flexibility and I have learned where I want the feets to meet the water. I just regret I didn't understand the importance of ankle flexibility before. About this, I have learned from the goswim98 training videos on internet. I believe both this team and Swim Smooth have made videos recommending the Finis floating fin, which is longer and more flexible than what is usual. My new fins are Cressi's Short Elastic Fin, very soft and comfortable.

USMaster Swimmer Magazine Fin Testing is not bad either: http://www.youtube.com/watch?v=w3JRV4JJD28&feature=youtu.be

Best / swim

After agonizing about it or a week, I just ordered a pair of the burner fins.not be use of speed, power or anything other than a desire to build up my butt without weight lifting. I have a flat butt.

Looking forward to trying them.

I use fins in legs only exercises. My typical swim day is 1 mile free-stroke without fins and 1 mile holding onto a kick-board with fins.

I just got the burner fins and plan to use they today. Yesterday I used my sons flippers from the dollar store. I moved so fast that I accidentally crashed into the wall at the end of my lap!

Embarrassing!

I've done that
I love the TYR Burners because they work the legs more without reducing the total work done. Bigger fins seem to encourage more "coasting." But then that is the point of full size dive fins.
As I have lost weight and gained strength and endurance I moved from mid length to shortie fins and now more laps without them.
Have fun

I find that with the fins I'm lifting too much out of the water. Im really buoyant anyway. What's the trick for using fins?

Try the shorter fins. Less "lift."

I have finally reached the point that I old use the fins for kick drill laps. Took some time to get my upper body in shape. Plus finally cutting down, and next week cutting out, a beta bl;ocker that limited heart rate has made a huge difference.
\My problem early on was that I tending to sink my legs. The mid fins helped get me in better line, worked my legs and decreased the stress on my bad shoulder. All of which helped me swim longer and improve endurance. As I lost weight I went to shorter and shorter fins.
It felt really good when I finished 5km without fins the first time.

My fins gave me a horrible calf cramp. It's back to plain feet for me.