STREAMLINE EXPLAINED (HOW DO DRAG FORCES INFLUENCE MY BODY IN SWIMMING?)

"Streamline, streamline, streamline", if I had a dollar for each time I say this word, I'd be a multi-billionaire at this stage, live in a mansion and have my own private 50-meter pool with a retractable roof.

If you visit this swimming blog often, you have read it over and over in my posts.

So, what is this mysterious streamline and why is it so important in swimming that everyone obsesses about it so much?

In laymen's terms, streamline, in swimming, means maneuvering your body into a position of least resistance while in the water.

So when you swim through the water, your body is as stretched out and straight as possible.

Just think of a regular 1-meter straight pole like a broomstick without the broom part as opposed to a small tree with branches sticking out.

If you throw the broomstick in the water in a vertical position, then it nicely slices the water until it hits the bottom.

If you do the same with the small tree, chances are that it will not even get fully submerged.

The same principle applies to your body in the water, the more streamlined your body is, the easier and faster you can swim with less effort.

If you think, this is only for competitor swimmers and not for me, think again.

The better you are positioned in the water, the more enjoyment you will have from swimming and the more you can swim and learn.

The main force that we are fighting in the water when we learn to swim is gravity. If we didn't take a breath, our body would sink as a rock due to gravity.

However, after we overcome the gravity factor and are strong and skilled enough to float without a hassle, we start focusing on reducing or eliminating other forces, mainly active drag forces.

The swimming science experts have currently identified 3 types of drag: form drag, frictional drag and wave drag.

The form drag is caused by our human non-fish like body shape which causes the turbulence around our body when we swim.

The friction drag is the result of the water flowing over your body and thus causing friction and slowing you down.

The wave drag, as described in the Journal of Biomechanics in the scientific paper Wave drag on human swimmers is caused by the energy required to cause the waves which follow your body when you swim and it also accounts for a larger chunk of the drag on a human body from the three drag types.

There are of course other forces that act on our body when we swim, but these are secondary in the streamline discussion.

Ok, now we know what slows us down in the water.

So, how can we decrease these drag forces to become faster and more efficient in our swimming?

Since the wave drag seems to play the biggest role in slowing our swimming down, let's focus on it first.

As described in the many scientific publications, wave drag increases as our swimming speed increases. In other words, as you swim faster, you are also causing more waves to be formed behind and around you.

And as we said above, the more waves you generate around you, the more wave drag.

Here are a few simple tips on how to be more streamlined and decrease the negative forces that slow you down.

1) Push off the walls at lower depths

Do not push off the wall at the surface.

The research has shown that the wave drag is very small or non-existant in greater depths, so if you push off at about 0.5 - 1 meter underwater you will actually swim faster than if you were at the surface.

That is one of the reasons why underwater dolphin kick is the fastest stroke out there and was unofficially coined the "fifth stroke".

This is also the reason why FINA has made a rule that a swimmer cannot swim more than 15 meters underwater from any turn or start.

2) Hold your streamline when you push off the wall or right after start.

Here we get into the term of real streamline and the form and friction drag reduction.

When you read in my posts or hear your coach say, hold your streamline, this is what he/she means.

Arms are extended above your head. Palms of your hands are on top of each other and are locked together by the top thumb.

Arms are fully straight and are squeezing your head right behind your ears.

If you are flexible enough, you can also try to overlay as much of a forearm over the other as possible and try to reach out of your shoulders as far as your body allows you to, so there are no air pockets around your neck.

3) Maintain a proper head position

Do not look where you are going and reduce the drag forces acting on your body at the same time.

Always look down when swimming freestyle and up when you swim backstroke.

During butterfly, your head is down for most of the stroke and only comes up to skim the surface during the recovery (when the arms come out of the water).

During breaststroke, it is the same, your head is basically just an extension of your spine and it does not move at the neck it is still and only moves when your body moves.

4) Keep a proper body rotation

Rolling from side to side on freestyle and backstroke with one arm extended in front is another way to reduce the drag. By extending your body forward in a straight line we are aligning our body into a more streamlined position, thus reducing our form drag and more than likely wave drag as well

5) Wear a swim cap

Wearing a swimming cap reduces the frictional drag since the surface on your head is more smooth.

As well as wearing a more inconspicuous goggle type helps reduce some drag.

6) Remove excess body hair

Smoother, hairless skin reduces the friction that the swimmer body is subdued to in the water, thus making the swimmer glide better in the water.

So, if you have ever wondered why competitive swimmers shave their bodies. Now you have your answer.

7) Wear a better suit

I hate to say this, but it is true that some suits are better than others.

Some swim suits also reduce drag and this is one of the reasons FINA (Swimming governing body) has band the full body suits from competitions and why there were so many world records broken in the last few years.

The suits compacted the body into a more streamlined position and helped the body with friction.

And here you have it.

So next time you are doing your laps or training in swim practice, remember, streamline is the key to success and repetition is the way you will get there.

Why not learn more about how your specific swimming style can be improved to reduce drag?