Why is it important? We need to kick for two main reasons: to keep a good body profile – that is to keep our bodies as horizontal to the water’s surface as possible - as well as to balance our body’s movement, especially in delivering an effective body roll. For most of us, our legs tend to drop when we are on our bellies in the water, creating more of an anchor than a second engine. If our body is not horizontal, we create unnecessary drag making the rest of our stroke work harder than necessary to pull ourselves through the water. Try using a pull buoy for a few laps and then take it away to see the difference. We should aim to feel the same horizontal body sensation while swimming without a pull buoy that we get from using one.
Why may it not be as important as we might think, especially for distance swimmers? We get very little propulsion from our kick. Even elite swimmers get no more than about 10 percent of their propulsion from their kick. Studies have shown that we tend to expend some 400 percent more oxygen in our quadriceps muscles (our thighs) compared with our upper body muscles. So, unless you want to put everything you’ve got into a final sprint, slow your kick down; you will only waste energy which should be better directed to your upper body. Think of your arms as the ‘paddles’ that pull your body through the water.
How to kick properly. We need to kick so that our legs follow smoothly behind our torso and not interfere with the ideal smooth streamline flow produced by our bodies moving horizontally through the water. A good visualisation technique is to imagine swimming through a cylinder or a tube (everyone’s – mine at least - all-time hero, Murray Rose, used to imagine swimming through a worm hole!). If we have a poor kick, we either do not kick sufficiently, we kick too hard or we use kicks that are too large. We should kick with ‘long’ legs, meaning as long as we can make them, maximising the distance from our fingertips to our toe tips, with no or very little knee movement, with ankles in plantar flexion (meaning with feet and toes pointed) and quite small kicking movements. The fulcrum/hinge for our legs should be at our hips, never at our knees.
Kicking patterns. A kicking pattern describes how many kicks are employed for every stroking cycle. What might be called a ‘normal’ kick is a four-beat kick, meaning that you kick four times with for every cycle involving both the left and right arms. But distance swimmers typically use a two beat kick whereby they do a type of long flick kick with their left foot when they stroke with their right arm and with their left foot with their right arm. Clearly, this consumes less oxygen than a four or six beat kick and so allows for more energy for the upper body in distance swimming or endurance events. It is easier said than done but it does improve with practice. It is also more easily done in salt water which is more dense than fresh water and so easier to achieve a horizontal body profile. Sprint swimmers will often employ a six beat – or sometimes even an eight beat kick – especially as they approach the finish.
So why should we do kicking training? In our modern lifestyles we do a lot of sitting at a desk or in a car and we tend to develop tight hip flexor muscles and poor core and glute strength. Good kicking drills can help improve those problems. And while kicking may not be as important as we may have thought, it is still necessary.
Kicking training tips. Do use fins/flippers – but not all the time as there is a risk of becoming dependent on their ‘outboard motor-type’ push-along. Long flexible fins help develop a swimmer’s hip, leg and glute strength and promote effective and efficient kicking. Short, stiff fins tend to promote kicking from the quads and knees rather than from the whole leg. Gently tighten your abdoms (try pulling your belly button towards your spine) as well as your buttock muscles (glutes) when you kick. Good coaching will employ various kicking drills with and without fins. While we normally concentrate on freestyle kicking, the same kicking technique can be used just as effectively on the back and the side as well as the front. Dolphin kicking (both legs together as used in butterfly), with and without fins, provides a good variation.