Using swim fins is the best way to improve ankle flexibility, kick specific leg strength and neuromuscular patterning.The key to fast, efficient kicking is foot plantar flexion flexibility.
Triathletes usually have strong ankles and have decent dorsiflexion (ability to pull toes towards shins) from biking and running. Kicking with fins increases the flexibility of the top of the foot and shin because the large surface of the fin catches more water, forcing the swimmer to plantarflex.
One of the biggest benefits of fins for triathletes is an immediate improvement in body position. Triathletes tend to swim with hips and legs trailing well below the surface of the water. By strapping on a pair of fins the lower body is brought to the surface with a small amount of kick.
At least 80 per cent of propulsion in freestyle comes from the arms. By bringing your lower body into the proper position, fins allow you to focus on improving your arm technique. This is espe- cially true when doing drills that require you to swim slowly or drills that require an efficient kick, such as single arm. I have seen triathletes struggle to simply breathe and not sink while doing drills – let alone do the drill properly. Fins allow you to execute drills properly and therefore develop the proper neuromuscular firing and muscle memory.
Start by incorporating 200 to 300 m of fin use per week and build up to 10 per cent of your weekly swim volume as needed.
Remember that whenever you are using your fins your ankle flex- ibility and strength will be improving – you don’t need to do any specific sets for these benefits. You can build the use of fins into any of your swim workouts.
Most triathletes won’t go to the pool without their pull buoy because it helps them with their body position and eases the work done by their legs. I suggest adding a set of fins to your tool kit: you may be surprised at the improvements to kicking efficiency, body position and arm technique.