Probably the most common mistake people make when finning underwater. We call it the “bicycle flutter kick” because it follows the same pattern of movement as the one we would be using if we were pedaling a bike.
What we can easily observe is a distinct forward and backward motion while rotating the ankles and lifting the heels at the same time. When we bend the knee, all we do is move the fin through the water. There is almost no “catch” of the blade this way, resulting in no propulsion.
The only time we “catch” water is when we push the fin forward. When we kick, almost all of the strength comes from the quads. If we continue to kick like this, then we are most likely going to fatigue very quickly as we are not spreading the energy used by using the core, calves and back of the legs.
Naturally, we develop bad habits all the time. We usually see bad habits more present in self-taught divers such as spearfishers or divers transferring from a scuba diving background. Any instructor will attest to how much easier it is to teach a complete beginner how to flutter kick compared to someone who has been practicing for a while.
It is a little more difficult to relearn skills that we have already developed. Having built a lot of muscle memory over the years, we have to apply more effort to change our habits than from learning completely from scratch.
One of the best ways to adapt and change our technique is to film ourselves and analyze as much as possible. This way, we can see what’s going on, because what we feel we do and what actually occurs are completely different realities.
When it comes to visualizing how to change ourselves, it is very important not to think about what we don’t want to happen, but visualize what WE DO WANT TO DO. This is a basic psychological approach for self-improvement.
If say, for example, I want to change my knee bend and if I am thinking “don’t bend my knee”, “don’t bend my knee”, then I am already thinking about bending my knee! This is an example of a double negative! Instead, a better way of thinking about it is to think about: I am going to keep the knee straight, while I doing a small bend to aid-in the snap.
So, to fix this, training with shorter fins to reduce resistance is recommended. This will make it easier to develop better muscle memory and aim to keep the knee straight, only allowing a 30 degree angle, or less.