I've been swimming for the last couple years and currently swim 4 times a week. Two of those days I swim in the morning, the other two are in the evening. Whenever I swim in the evening and swim a set using swim fins my feet and toes tend to cramp up the next swim set.

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I've tried lots of things, potassium and water because I read they help with cramps as well as stretching before and after the swim fin set. So far, neither has worked. My only other thought was perhaps the fins are the source of the problem. Swimming in the evening without using the fins doesn't bother me, so its not just because I swim in the evening. At the same time, if I use the fins in the morning, I don't cramp up either.

I was just hoping someone here might have a suggestion and/or solution as to what may be causing this.

  • Too tight? My feet cramp with fins that squeeze my feet. Have you tried larger fins, ideally those with that fit a wetsuit boot? Sep 23, 2011 at 14:07
  • It almost seems to happen more with bigger fins. I think its because with bigger fins, my feet have to work harder to keep them on my feet.
    – Anthony
    Sep 25, 2011 at 4:25
  • I had the same problem. For me it helps to keep my feet (and also legs) as much relaxed as I even can. No pressure, no quick movements, no unnecessary muscles contractions. Or I'm trying to push harder by my thighs and only let calves to follow "the wave" without any additional energy. Your cramp-resistance should increase with every training. After proper warm-up and stretching and some time spent in that relaxed position I can swim with fins pushing really hard and without cramps. I'd try to give it even more time... it will pay in the end. Good luck!
    – tsykora
    Jul 8, 2013 at 15:19
  • Late comment but if the fins don't fit your feet, the unconscious tendency is to "grip" with your toes, which can easily lead to foot cramping.
    – JohnP
    Sep 6, 2014 at 4:04

4 Answers 4


There are various reasons for using fins. Don't give up on them as they can be an excellent training tool.

As a swim coach, I do not take a 'one-fin-fits-all' approach, especially with training adults. Yes, foot size does matter and if the fin is ill-fitted (too small OR too big) the foot and ankle and foot will have to flex/tense more to use the fin.

In addition, the level of resistance the fin provides will also influence cramping. If you have never used fins before or your ankles are weak (in respect to this exercise), a larger blade on the fin will increase the chances of fatigue and/or cramping.

Starting off with a split fin or, even better, a cut or short fin, will help you begin to increase ankle/calf strength. You can progress to a larger or firmer blade from there.

Here are a couple of fins I like for starting off:



I've personally taken my long fins and cut them to the size I want.

So you know, I have no allegiance to any one particular brand, just know what I've found works best during training (for myself and my swimmers)

Also, wearing socks to make the fin 'snug' helps - can eliminate blisters, too.


According to Swim-City, your foot can cramp up if you deliberately point your toes when you swim. That's because in order to do so, you have to contract the muscles that run up the back of your leg, including your foot arch. This can be exacerbated by a variety of things, one of which is wearing fins:

Wearing fins and kicking fast – for some reason the body insists on trying to control any swimming-aid attached to the foot (especially with short fins because the foot has to bend instead of the flexible blade on long fins doing the work). These unnecessary muscle contractions eventually lead to cramp unless you have the ability to be and stay relaxed.

  • I think I may end up not using fins anymore. I'm not sure exactly how much benefit I gain from them at the moment anyway. They do come in handy while working on my butterfly technique though.
    – Anthony
    Sep 25, 2011 at 4:24

The selected answer doesn't mean that you shouldn't use them, and is not the only reason for cramping. Sizing is the biggest factor in my swimmers. You may also acclimate by using them only a little bit on the first day and working up slowly to build foot and calf strength. Personally, I had foot cramping problems until I switched to tyrs a half size over my shoe size.


Perhaps fins are like running shoes. It seems I can wear a pair for about 5 months (swimming about 10 miles a week). After that period, the fins start to stretch out around the toe area. As soon as I replace them I'm good.

I too cramp only at night, not during my early morning workouts when my fins start to wear. I like TYR fins too. Reasonable, comfortable, and efficient.

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