Swimming with Fins

A Guide to Better Kicking and Body Position in Front Crawl

Read the following with a caveat that you'll understand that the opinion expressed below, is with the narrower scope, i.e. restricted to, the usage of flippers in the training of the front crawl stroke predominantly, even if some (or most) of it, in principle, may apply to other competitive strokes as well.

SWIMMING FLIPPERS (FINS) in swim training:

Albeit the kick, all by itself contributes to less than 15% of the propulsion even in the elite swimmers (and less than 10% of it, in us mere mortals) it is important to develop the kick, not just for that minute amount of propulsion, but more so for the better body position which comes on account of a good kicking technique.

The much larger surface area of the fin, vis a vis the naked foot, adds a lot of "resistance"... this is a good form of "resistance training" to develop the kicking muscles... and kicking against this added resistive force also helps with increasing one's ankle flexibility. It is this ankle flexibility that's the key difference between elite swimmers and "average kickers". Any added degree of additional range of motion is a benefit an average swimmer should always look to add to their kitty.

Adult-onset swimmers and triathletes from running backgrounds, who usually have low ankle flexibility, are not able to push sufficient water, not only in their "down-beat", but especially so in their "up-beat" component of their kick. Therefore, they also lack the very "feel" of the kick the elites have. Adding fins allows the luxury of that 'flexibility' and resistance, both of which the fins provide many times over what one would ever be capable of with bare feet. This helps swimmer experience and hence probably help develop that elusive "feel" they would otherwise never experience with their naked feet.

I fully agree with the host of coaches who believe in and swear by the usage of single fins (one foot bare, one with a fin) in conjunction with the use of a single paddle on the opposite hand, to greatly enhance the feel of the "cross-connection". That's another great use of a fin!

When swimming at a faster pace the resistive (drag) forces are much greater. (The resistive force goes up exponentially with increasing velocity.) Using fins (flippers) to go at a faster pace with relatively lower effort attunes the body to (or creates the awareness of) sensing those drag forces. When one is better aware of those, then it's the first step towards taking steps towards understanding the causes and therefore minimizing those forces apart from developing a sense of the way water behaves around one's body at those higher speeds.

Just as using a pull buoy helps with body position, the fins, more often than not, allow a better body position compared to when swimming without them.

For swimmers who usually have a poor body position, this allows them to learn the dynamics of forces when swimming with the much more horizontal (correct) body position. This habit subconsciously develops in the more correct body positions.

However, the most important use of fins in my opinion is to help the swimmer do a host of drills a lot better than they could do those without fins. The added propulsion and better body position help swimmers focus on doing the drills better. As a swim stroke analyst, I am slightly biased to the extent that I state that swim technique is of paramount importance, when it comes to improving one's swimming. The added propulsion from the fins allows the swimmers to go faster. This is a great aid to travel at a certain speed without using the upper body as much. Therefore it takes away a tremendous amount of load off the shoulders. That's the very reason many elite swimmers and their coaches recommend the usage of fins during the warmup and swim-down sets. This is useful when a swimmer is recovering from a shoulder injury too.

Having mentioned all of this, a word of caution though... one must understand that fins mustn't be "over-used" in training to the point that they become a crutch. Just like all good things, anything in excess is not a good thing, one needs the right balance.

Now... to answer the question "Which Fins... long or short?"

My take:

Short (like GMC or Arena Powerfin Pro, etc.) are for advanced swimmers. The advantage is, that the kicking frequency remains a lot closer to the natural "fin-less" kicking frequency compared to when using the longer fin, where the natural kick frequency goes a lot lower.

Medium flexible fins (like Finis long floating fins, etc.) are better for beginners and intermediate swimmers. These provide more propulsion for drills. And these also loosen the stiff ankles better (increase RoM). But people with very stiff ankles, like runners who turn to swimming, tend to have cramps in the beginning. In my opinion, the stiff fins and the super long fins (like those used in scuba) are strict NO - NO for swim training.

P.S.: Although the "generic fin" can be used to train the kick in other strokes, for breaststroke, one should use specialty fins made for the purpose and refrain from using the generic ones.