See link to video

 The type of fins you should use when swimming in open water for any of these professions is a strong SCUBA type fin that can also substitute for SCUBA diving.  Getting your ankles used to the strain of the kick takes a few weeks of 500-1000m swims, but the initial pain will go away as long as you incorporate swimming with fins regularly into your program.  I recommend anything made by Cressi or the US Diver’s Rocket Fin as it is used by many special operations training programs.  You will need to wear booties with these types of fins and not be able to use these fins bare foot.

Here is the email question from a young man preparing for BUD/S by swimming with a newly purchased pair of fins.

 Recently I bought a pair of Rocket fins and booties.  Up until now I have been using soft fins for your workouts and I have been able to fin 1 mile under 30 minutes with soft fins.  With rocket fins, however, it feels much more awkward and painful.  It seems as if my arm-pulls get me more propulsion than the flutter kicks with rocket fins. 

1.  Is there a specific technique to finning with rocket fins?  Does the kick have to be a certain width?  It seems that bigger kicks give me a stop/start movement and interrupt my momentum but while smaller kicks give me constant movement they still don't seem to propel me that fast.

There is a technique to swimming with fins, but no one best way as we all have different kick strengths.  I have found that athletes in sports like football and soccer may not be the best swimmers without fins, but when they place a pair of SCUBA fins on their legs, they are faster than most people in the class.  This is because they have well developed leg and hip strength and can use bigger kicks to build speed.  Some athletes with less strong legs / hips tend to still swim fast, but are required to kick using smaller strides at a faster pace.  You have to find out what works best for you personally.  You will want to learn how to swim on both sides as well because you can alter your kick as long as your top leg always extends forward on both the left and right side.  Learning to swim on both sides offers a form of “rest” by changing the pull – push stride of your left / right leg.

 As far as arm pulls and breathing as pictured in the video, the arm pull can be used as another method of propulsion, especially if you need to rest your legs by skipping a few kicks throughout a long distance swim.  Many people like to do a slight pause of kicking when breathing and recovering the arms forward again to remain streamlined.  As with any swimming, recovering your arms should remain stream-lined and not an obstacle to forward motion. 

2.  The fins seem to cause pain in my feet after a couple hundred yards and stiffness up the front and side muscles of my shins.  Is this just a matter of conditioning and getting my feet used to wearing these fins?

It is a matter of conditioning.  When first wearing fins while swimming, you should only swim a few hundreds yards and push slightly past discomfort in the ankle and shin area.  Do not push too hard and for too long at first as over use injuries like tendonitis in the feet and knees can flare up causing you to only be able to swim or run with severe discomfort or injury.  This process usually takes about 10-15 swims or two to three weeks of swimming with fins.  It is recommended to swim 500m with fins and if they start to bother you, take off the fins and swim 500m without, then try fins one more time until discomfort returns.  Do this for a few weeks and you will be able to add greater distances each time you swim. 

Good luck with adding fins to your swim workouts.  It takes time to get comfortable so do not feel weak if you can only swim a few hundreds yards the first time you wear a “real” pair of fins.  Feel free to email me if you have any questions at stew@stewsmith.com.

__________________________________________________________________________________________