It looks simple, but it is profound.
Streamline is the foundation of swimming, but it also contains the essence of swimming.
I will introduce a very simple practice method that will help you make the leap from a beginner to an advanced swimmer in one fell swoop.
Simple practice on the “Floor”
1.lie on your back on the floor.
2.Then, slowly raise both hands above your head, palms together.
That’s all. Quite simple.
Now, let me explain.
Explanation
resistance and buoyancy
Streamline is the foundation of any swimming technique.
With the correct posture, even beginners can smoothly and swiftly advance 10 meters.
The key points here are “resistance and buoyancy”.
If streamlining is done correctly, the swimmer can swim with minimal resistance and maximum buoyancy.
However, if this is not done, the swimmer will be inefficient, only draining his/her energy and making it difficult to move forward efficiently.
Water is 800 times denser
The density of water is about 800 times that of air. Movement in water is subject to resistance 12 to 15 times1 greater than on land.
In other words, the key to improving swimming for easier and faster swimming depends on how much you can reduce water resistance.
When you walk in the water, you feel your entire body being pushed back into the water.
At this point, it is much easier to move forward by turning the body to the right side.
The less area that is in contact with the water, the less resistance there is, and the less force is required to move forward more quickly.
The two main causes of resistance in streamlining are the “head” and the “legs”.
Beginners tend to want to look up, whether out of fear of the water or anxiety to see what is ahead.
However, this is something that needs to be improved. Because,
- Raising your face increases water resistance
- Raising your face makes your legs sink
The more you raise your face (i.e., lean your head back), the more your head protrudes from the line of your spine.
In difficult terms, this means an increase in frontal projected area.
The human spine is gently curved so that the pelvis, shoulders, and head are aligned with each other.
In other words, when the face is facing forward, everything is in the proper position.
If you lean your head back, only your head will protrude from the line.
To reduce water resistance, we need to reduce the frontal projected area as much as possible. In fact, we want to avoid sinking legs for the same reason.
When the legs sink, they protrude beyond the torso line and cause increased drag.
If you are familiar with car racing or bicycling, slipstreaming or drafting would be easier to imagine.
And here is where the buoyancy comes in.
buoyancy acting on a human body
The specific gravity of a human being is about 0.98 with air in your lungs. In other words, it is 2% lighter than fresh water (specific gravity 1.00), allowing 2% of the total body to float on the surface of the water.
(cf.公益財団法人 日本セーリング連盟)
A person weighing 70 kg is calculated to have 1.4 kg worth of parts out of the water.
The more you raise your head, the more the rest of the body (and legs needless to say) will sink, and if the head is under water, the body and legs will float.
The “head” and “legs” are in a seesaw relationship. If you raise your head, your legs will sink.
Swimming is a science.
That’s where “lying on your back” comes in
When lying on your back, the line of your head and spine are aligned and your eyes settle directly above (on the ceiling).
In fact, this is the ideal posture that minimizes the frontal projected area.
Next, as you raise your hands…
Do you feel your stomach dip and your strength increase?
This is the state of being switched on your core.
The legs sink because they are not supported by the core as the head rises.
It is a truth that no one tells you, but the basic posture for swimming is always to squeeze your stomach.
Lying on your back is the best (in my opinion) way to develop this sensation.
Also, it is quite important, but don’t you notice that the part of the body that touches the floor when you lie on your back is exactly the same as the part of the body that is out of the water when you do streamline in the pool?
In other words, if you flip lying on your back position 180° and assume that the floor is the surface of the water, you have created the ideal streamline posture (In other words, the perfect horizontal posture).
Since I developed this practice, my streamline (ideal streamline with minimal resistance) have improved dramatically.
Most importantly, I like it because I can practice easily without going to the pool.
When I go to the pool, I always make sure I am lying on my back by the pool before swimming.
I close my eyes and drop the sensations in my body, and when I get in the pool, I recreate those sensations and try streamlining.
That’s my favorite routine.
※Supplemental information※
Squeezing your stomach is one in which the center of gravity has shifted to the chest side.
This can be rather felt if you try it in the standing position. When you squeeze your stomach, don’t you feel the tension increase around the lower shoulder blades?
When you relax your stomach from there, you will feel the center of gravity drop down to your lower abdomen at once.
If you squeeze your stomach, you can use your core and at the same time shift your center of gravity upward, which makes it easier for your legs to float.
Intermediate level for further exploration
Simply ‘1. lie on your back 2. raise your hands above your head’ will improve your streamline considerably.
But if you want to refine it even further, you’ll want to be aware of…
①Stretch tight to the toes.
②Align both knees together with a tight fit so that they are not separated from each other.
③Stretch not only the toes but also the fingers.
④Don’t bend your back too much. Keep it down with your stomach.
⑤Tighten your elbows. But don’t tense your shoulders.
(Stretch from the shoulder blades)
①~③:Imagine stretching your whole body like when you stretch after you woke up.
And ② is quite important. If this is done properly, resistance is reduced and the advancing distance is further increased.
④:It is easy to get the feeling of ‘holding the lower back down with the stomach’ as you slowly exhale while lying on your back.
⑤:Good luck！
Ideally, the whole body should not be fully relaxed, but not unnecessarily tense.
Not a plastic bag floating on water, but a surfboard as it were.
Can’t I just do it using the wall?
You could do the same exercise with a wall instead of the floor, but a wall is not sufficient to relax the legs.
It is also easier to grasp the feeling of firm extension from both hands to the toes when gravity is not applied in the direction of the body axis like when you on your feet.
Therefore, to hone your senses, I recommend doing it on the floor.
- Resistance depends on the shape and the speed at which it moves. A pointed cone has less resistance than a cylinder, and the faster you move it, the greater the resistance, and the slower you move it, the less resistance. In extreme cases, if it does not move, the resistance is zero. ↩︎
