Kicking like a banshee during the swim leg of a triathlon is NOT a good idea. Doing so will not make your swim leg much faster. But it will, most likely, make your bike and run legs much more difficult. 

Conserving your legs for the bike and run will easily make up any time gained from kicking hard during the swim.

Having said that, your legs must work in concert with the rest of your stroke. While you don’t need to kick hard, your legs should help you balance.

while your legs aren’t much of an asset during the swim, they can be a major liability. Poor kick technique can create drag and alter a swimmer’s body position, making the swim much more difficult than it needs to be. For that reason, it’s good to practice and develop a sound freestyle kick.

Additionally, kicking in a pool is good exercise and can help build leg endurance for the run and bike sections. So, adding kicking sets to your workout is not lost — even though, during a race, you will only use a lazy kick for rhythm and balance.

Before we discuss what to do, let’s show a few examples of what not to do. See if you identify with any of these characters…

The Biker

The Biker tries to churn through the water by circulating water with their knees and feet. They bend their knees and try to “pedal” themselves forward. By doing so, they create a lot of drag as the water hits their thighs. (See Figure 3.)

The Splasher

The Splasher’s feet are very high and will often  break the surface to create a big splash. (See Figure 4.) It’s important to know that splash does not equate to speed. Lifting the feet above the surface brings air into the water, which means the swimmer is kicking air and not stable water. Think about what happens when a motorboat propeller is lifted halfway out of the water. The propeller instantly looses some traction.

The Toe Knober 

The Toe Knober has a hard time keeping their ankles flexed. As they kick down, their natural tendency is to bring their toe towards their knee.  They have a very rigid kick. (See Figure 5.) 

Do This…

The freestyle kick is often described as a “flutter kick” because the motion is limited to small up/down kicks. It’s also described as a “whip kick” because the motion starts from the hip, followed by the knee and foot.

Any surface movement should come from the feet churning stable water, and not from bringing the feet out of the water. The feet must stay in the water to give propulsion.

It’s important that the legs remain long; the foot remains flexed; and the hips, angles and knee joints remain relaxed. Rather than trying to kick water backwards to propel you forwards, think about kicking water up and down. The sole of the foot kicks water up and the top of the foot kicks water up. The knee shouldn’t bend much…only enough to support the whip effect.

Kicking on your back is great practice — especially if you’re a biker, splasher or toe knober. As you kick on your back, take a quick look at your knees and feet. Be sure that they aren’t breaking the water. If the water above your feet looks like it’s boiling — from kicking water up to the surface with the top of your foot — you’re doing it right.

Using fins is also useful to help practice the kick motion. It also helps encourage ankle flexibility. But don’t become dependent on the fins! Many of the kicking sets at encourage swimmers to use fins for half the reps, then remove them for the second half. That way, fins help establish good technique before repeating without fins.

Again, a strong kick isn’t a skill that you’ll use during your race. But your legs help you balance. For many beginner triathletes, freestyle kick is a very slow and tiring exercise. Stick with it.