For example the swimmer below is bending a lot from the knee as he kicks. Notice how the whole of the front of his thigh will be causing drag by pushing water the wrong way (forwards):
If you're learning to swim freestyle it's quite likely that you are kicking ineffectively and this is making things much harder than they need to be. By this I mean either bending your knees too much when you kick, kicking too hard or even dragging your legs low behind you making staying streamlined virtually impossible.
There's no magic to kickING efficiently, it is actually really easy when you know how! Studies into Ian Thorpe’s leg kick showed that even he could only generate about 10-15% propulsion from it (with super flexible size 17 feet!), the vast majority of his propulsion was from his upper body. Pool sprint swimmers may wish to develop a strong leg kick but for the majority of people doing triathlon or long distance and open water swimming, you should be looking to minimise your energy expenditure from your leg kick. You are just using it to keep your legs high to reduce drag.
Here's three of my favourite exercises to try to improve your kick:
1. Lie on your front on the floor or poolside with your forehead down, body straight with legs together. Now lift one of your legs up straight. Look behind at what that leg is really doing - are you bending at the knee? If you are then you need to learn to lift your leg up WITHOUT bending your knee, so you can actually kick from your hip. Use your lower back, glutes and hamstrings to pick that leg up about 15cm / 6 inches off the ground, keeping your knee straight and your toe pointed. Repeat a few times on each side, then have a go alternating with a faster rhythm as you would in the water.
2. In the pool, hold the wall or steps with both hands and keep your arms straight. Put your head in the water looking at the pool floor beneath you and gently exhale. Lift your legs up so your body is fully horizontal kicking lightly with your new straighter leg technique. Think about trying to keep your legs within what I call 'the shadow of your body' - no deeper or wider than your torso behind you.
Turn your feet in like pigeon toes and brush your big toes together lightly as they pass. Close your eyes and tune into what you can feel - can you feel the surface of the water or bubbles with your toes? It should feel very soft as you lightly break the surface with your ankles (don't lift your whole foot clear of the water).
Kicking like this will remove the need to use lots of energy but keep your legs high up to reduce drag. If you keep your core engaged and you are kicking correctly from the hip you'll notice your body starts to roll slightly with every kick, right up to your shoulders!
3. Perform a normal torpedo push off with your hands streamlined one on top of the other, head underneath your arms and push off the wall, legs straight and together, and toes pointed. Just at the point that your momentum slows, start to lightly flutter kick. Tap your big toes together as they pass, let your ankles stay floppy and let the kick bring your legs up high. Perform this drill without lifting your head to breathe if you can, if you lift your head you will immediately feel more downward pressure on your legs.
Whilst moving down the pool, make your kick gentler and gentler until eventually you feel a threshold and they start to sink. When you're kicking with good technique you will be amazed at how gently you can kick without sinking. This low level of kicking effort is what you should be aiming for in your full freestyle stroke - if you are kicking any harder you are burning a lot of energy and oxygen doing so which will leave you really short of breath.
Push off again but this time go into your full freestyle stroke, reproducing that gentle kicking technique you just learnt. Remember nice straight legs, floppy ankles, feet pointed inwards. Let your arms do the work instead and feel the difference.
So, get down to the pool and use these new techniques to start kicking effectively. You’ll be amazed how much easier swimming freestyle will feel - let your arms do the work!
Post on the comments of this post and let me know how you got on!
Also see our full article on leg kick on the Swim Smooth website here: swimsmooth.com/kick