Welcome! If you’re looking for information about swimming fins, you’ve come to the right place. First things first. What are swim fins and how do they differ from dive/snorkel fins? While they seem similar, not all fins are created equal.
Swim Fins are used for swim training (to help you become a better competitive swimmer), and to add resistance to your kick which helps build muscle while swimming. They are most commonly used in a swimming pool. And while you could use them when swimming or training in the ocean, these are not the same thing as “dive fins” or “SCUBA fins” which are used, you guessed it, for SCUBA diving or snorkeling.
There are many differences between the two, but the defining factor is that dive fins feature a longer blade, and are designed for a slow, broad kick, used to overcome the drag imposed by dive equipment. (Divers typically don’t swim using their hands).
Swim fins on the other hand (see picture above) have a much shorter blade, which help to build muscle by adding resistance to your kick as well as many other benefits discussed below.
The Benefits of Swim Fins
We know that swim fins increase the surface area of the foot, providing added propulsion and increased speed while swimming. But how does this actually help you become a better swimmer?
For Strength Training
It may not be obvious at first, but when you’re using fins to swim faster, your legs are actually working harder than they normally would (without fins) to maintain that speed. Over time, your leg muscles become stronger which will ultimately allow you to swim faster and longer when you’re not using fins.
But if the goal is to make your legs stronger, why not just swim faster without fins? Well, you could probably kick twice as fast for about one lap, but you’d quickly find yourself out of breath and out of energy.
Many swimmers rely on the extra resistance provided by swim fins to achieve a strength and cardio workout. Why? Because kicking fast, but finless puts extra strain on your heart muscle, but doesn’t help your legs get any stronger since you can’t maintain that pace for a long enough time. Additionally, even though your heart rate will be elevated, it will most likely be elevated way beyond the upper limits of your target heart rate, which will quickly result in fatigue. So really fast kicking is no good for a cardio workout either.
Just like with traditional strength training, you should push the limits of your muscles to improve them, but you don’t want to over-work them, or attempt too many repetitions of the same muscle group without taking time off to rest. By using swim fins, you can work your legs harder without overloading your muscles.
Before we talk about the role swim fins play in a cardio workout, we need to talk about some exercise theory.
First, What is Cardio?
Using swim fins can increase cardiovascular health significantly. Cardio is a short term for ‘cardiovascular exercise’. The Latin prefix ‘card’ meaning of or having to do with the heart. So in short, cardio is nothing more than strength training for your heart muscle. Swimming with fins is just one of the many ways to get a good cardio workout. You could just as easily run, jog or jump rope. (But swimming is much more fun!) We’ll discuss swimming for cardio in just a moment.
In order to give your heart a good workout, your heart needs to be in it’s target heart-rate range for an extended period of time- usually between 20 and 30 minutes, and you need to be utilizing a large portion of your body’s total muscle mass. For an intense cardio workout, you also need to use both your arms and legs simultaneously.
Why Do Cardio At All?
The biggest benefit of regular cardio work is a stronger heart. The stronger your heart, the longer you can swim- or perform any other activity for that matter. In other words, the direct benefit of a strong heart is increased endurance. If your heart can supply blood (and thus oxygen) to your muscles more efficiently and for longer periods of time, your entire body will be able to perform better in physical situations which will, in turn, increase strength and stamina.
Target Aquatic Heart Rate
Your heart-rate while swimming or doing water aerobics will be much lower than it is on land, even though you are still receiving the same exercise benefits you would on land. If you’re swimming for cardio, you’ll first need to calculate your water target heart-rate. Remember- it’s NOT the same target heart-rate you’d use for running or jogging. A 13% reduction from your target land heart rate will yield an accurate aquatic target heart rate.
So What Does This Have to Do With Fins?
Here’s the problem. As mentioned earlier, in order to get a proper cardiovascular workout, you need to use a large portion of your body’s total muscle mass when exercising. Over 60% of your body’s total muscle mass is in your legs, so any proper cardio workout must involve heavy use of your legs. When running or jogging, this is easy. You’re already using your legs heavily, so a little bit of arm movement is all you need to maintain your elevated target heart-rate (which is key to a good cardio workout).
When you swim, however, your arms are used heavily for propulsion and the legs are often neglected. Sure, you’re kicking with them, but you’re working your arms far harder than your legs, and this isn’t very good from a cardio standpoint- you want to be using your whole body equally. The thing is, human legs weren’t designed for swimming. They’re extremely inefficient at it. The foot has very little surface area and just isn’t that great at propulsion.
So how can we make our legs work harder and still have enough energy for a solid 20 minute workout? I’m sure you’ve already guessed where I’m going with this: Swim Fins! The title of the site.
Wearing fins does more than make you look funny. They increase the resistance of your kick by adding surface area to your foot. The more resistance, the tougher the workout. And the tougher your legs work the harder your heart works. And it’s this elevated heart rate that, just like exercising any other muscle, makes your heart stronger.
Looking for a change of pace? You can also get a good cardio workout by treading water in fins, and tone your legs nicely while you’re at it!
Cardio For Weight Loss
Weight loss has been directly linked to an elevated heart rate. Although losing weight and burning calories is actually the result of higher levels of oxygen consumption, the heart is responsible for delivering that oxygen throughout your body.
When your muscles demand more oxygen (because you’re swimming, exercising, or running from a man in a hockey mask with a chain saw), your heart rate increases to meet the demand. Since it’s much easier to measure your heart rate than it is to measure your oxygen consumption, we’ll use heart-rate as an indicator of calories burned, even though oxygen usage is technically correct.
As explained above, using fins lets you exercise more muscle mass at a higher level for longer periods of time. And the more muscle mass you work, the more oxygen you use, and the more calories you burn. In short, you burn more calories because you’re able to work harder, with less fatigue.
As a bonus for those trying to slim down, calorie consumption doesn’t end when your workout does- you burn additional calories during the recovery period as well since your metabolism is still elevated for several hours afterwards. You also burn more calories simply by having muscle. Muscles burn calories even when your body is at rest- so once you build them, they’ll continue helping you lose weight for the rest of your life.
For Stroke & Technique Improvement
Many fins are positively buoyant. In other words, they float. That means that when you swim with them, the fins will keep your legs higher in the water encouraging a higher overall body position making you a more proficient swimmer.
We know that the increased surface area of the fin provides extra power to each kick making your legs more efficient at propulsion. But swimming with fins also forces your foot to extend and flex beyond it’s normal range of motion which, over time, will increase the flexibility of your feet and ankles. This increased range of motion will ultimately lead to additional propulsion and a more efficient kick without fins.
For Race Training
Fins allow you to train at race speeds without fatigue. This is important because at faster speeds, your kick is different, your arms spin faster and your body sits at a higher position in the water than during non-race swims.
Using Your Fins
The faster your kick and/or the broader your kick, the more drag is created. When swimming with fins you want shorter, faster kicks (14-18″ works best) to reduce drag. At slow speeds larger kicks the faster you go, the harder the work.
Types of Foot Pockets
The foot pocket (the part of the fin where your foot goes) usually comes in two styles: an open heel design, using a strap, and a closed heel that encompass the whole foot, like a shoe would.
The closed-heel design is not adjustable, so they are typically offered in a wide variety of sizes, usually one per shoe size. The closed heel fin design also provides a snugger fit.
The open heel design usually (but not always) has an adjustable strap that can accommodate many different foot sizes. This style of in is offered in a basic small, medium, large, rather than by shoe size.
While an adjustable strap offers convenience in that it is often easier to put on and take off (the straps usually un-clip or unbuckle), a closed heel transfers more power from each kick into the fin, since there is less play between your foot and the fin.
There are a few exceptions such as Alpha Fins which have a strap on design that’s not removable or adjustable. The easy on-off is a trade-off for a less precise fit.
A good fit will feel snug, but comfortable without being too tight. You don’t want to cut off your circulation, but the tighter the fit, the more power transfers from your kick to the fin. Loose fitting fins are inefficient and will waste your energy.
Closed-heel swim fins typically fit the same as your shoe size, although some brands like the Speedo Biofuse Fins run slightly smaller. If you’re right on the edge between sizes, you should probably go one size larger just to be sure. If the fin slips a little, you can easily add a pair of thin socks to take up the extra space.
Finis makes a good fin sock (called “skin socks”) made of swim suit fabric. Or if you prefer, you can also just use a pair of regular socks. You may also want to try a cheap pair of dress socks, if there’s just a small space you’re trying to fill.
Socks will also help prevent chaffing and blisters while providing comfort – especially with some of the stiffer swim fins. You will also have some protection from things on the pool deck and the locker room floor.
If you choose to use fins without socks (which I prefer, but you’ll need to experiment and find out what works best for you), you may get blisters when first starting out. A lubricant such as ‘snow-seal’ boot water proofer will help reduce chafing until your feet get used to the fins. Usually after a couple weeks of swimming with fins, your feet will toughen up and the blistering will stop. Just take it slow.
It’s best to try on fins in your local swim shop, or order from an online store with a good exchange/return policy. (I can recommend a few good places to buy online, just drop me a note.)
Fins are made from a variety of materials including rubbers, plastics, and foams. Fins can be anywhere from soft and highly flexible to extremely rigid and firm. Firmer fins provide more resistance than more flexible ones. The firmer the fin, the tougher the workout. If you’re just starting our with fins you’ll want to start out with a more flexible blade. The firmer fins should only be used after you work up to them. Think of it like weight lifting- when you first start, you want to challenge yourself, but you don’t want to take on too much at once.
Where to Buy
Some people have emailed me asking for recommendations on where to buy their fins. Your local Swim Shop is a great place to get swim fins if you’re lucky enough to have one in your town. Brick and mortar Swim Shops aren’t very common though, and dive shops don’t usually carry the kind of fins you’ll need for proper swim training. Personally, I like to get all of my Swimming Equipment from AquaGear Swim Shop, one of the best online swim stores in my opinion. They are always extremely helpful on the phone, and I usually get my order in two or three days with their standard shipping. Check out their Swim Fin Section to see the models they have available.
Swim fins aren’t too expensive, but since they’re easy to care for, why not protect your investment?
The easiest way to prolong the life of your fins is to give them a quick rinse with fresh water after swimming. Whether it’s salt from the ocean or chemicals from the swimming pool, these corrosive substances can slowly eat away at your fins over time, which can cause premature failure of the materials and decreased performance. Most pools and beaches will have a fresh water tap or hose you can use. Just ask a Life Guard or facility staff member if you’re not sure. Worst case scenario, you can rinse them in a shower since public facilities almost always provide them.
It’s also important to avoid walking in your swim fins. This includes on the pool deck, or on the pool bottom. The most obvious reason is the rough surface will scratch them. But walking in your fins can also permanently deform their shape. Swim fins were designed for, as the name implies, swimming! They may have subtle curves to their underside that aid in propulsion, but when you walk in them on a flat deck or pool bottom, your weight causes those special curves to flatten. This flattening can not only decrease your fin’s efficiency, but can also add drag to your workout! And that’s a bad thing. (Read the section on how fins work for more details.)
To avoid causing damage, you should always carry your fins to the pool side, and put them on while sitting on the edge of the pool, just before starting your swim. Make sure that when you rest between laps (and if you’re using fins you should be resting between laps, see above!), that you’re not standing on the bottom if the lane is shallow.
After swimming, your fins should be stored in a cool, dry location. Be sure to store them our of direct sunlight, as UV rays can cause them to break down prematurely.
Side Note: Sometimes fins are used on land as part of a therapy program (for helping people learn to walk again after an injury or accident). Of course this is OK because the fins they use will never be used for swimming.