"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've seen it over and over again. But what does it actually mean, and why do coaches obsess about it so much?
Let's dive in.
Short on time?
Watch this 5-minute visual guide to understand why "muscling" the water usually fails. We break down the "Broomstick vs. Tree" analogy and show you exactly how to position your body to cut through the water like a torpedo.
In simple terms, streamlining means shaping your body to move through the water with as little resistance as possible.
Think of your body as a broomstick versus a small tree. A broomstick slices cleanly through the water; a small tree, with all its branches, creates chaos and turbulence.

That's the difference between a streamlined swimmer and a floppy one. When you swim, the goal is to be the broomstick, straight, tight, and sleek.
Even if you're not a competitive swimmer, good streamline makes every lap easier, faster, and more enjoyable.
The better you are positioned in the water, the more enjoyment you will have from swimming and the more you can swim and learn.
While pool swimmers streamline for speed, open water swimmers streamline for safety.
Efficiency means energy conservation. When you are 500 meters from shore, every ounce of energy you save by reducing drag is energy you keep in your "battery" for navigating currents, waves, or cold water.
Tip: Using a low-drag 360swim Open Water Buoy helps you stay visible without ruining your streamline.
Once you've learned to float and overcome gravity, the next challenge is drag, the invisible resistance that slows you down every time you move through water.

The better you understand drag, the better you can control it.
Swimming scientists identify three main types of drag that affect your body, form drag, frictional drag, and wave drag. Together, they determine how efficiently you move.
Let's break them down quickly:
Form drag:
Caused by your body's shape and how much turbulence it creates. Humans aren't shaped like fish, so we naturally create resistance.
Frictional drag:
Created by water flowing over your skin, suit, and hair. The smoother your surface, the less friction.
Wave drag:
The big one. As described in the Journal of Biomechanics' paper "Wave Drag on Human Swimmers," wave drag is the energy lost to waves you create at the surface.
The faster you swim, the more wave drag builds up, unless your technique improves. While speed naturally creates waves, fighting the water creates walls. The goal isn't just to swim fast, it's to swim cleanly without creating a splashy mess behind you.
Wave drag plays the biggest role in slowing you down, and luckily, it's also the one you can most directly influence through better streamline technique.
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?
🎧 Listen: The Science of Drag (Audio Deep Dive)
Prefer to listen while you commute?
In this episode, we go beyond the basics and discuss the brutal physics of the "Square Law" (why swimming 2x faster creates 4x the drag). We also debate the 2009 "Super Suit" ban and teach you the "Wall Test", a simple living room diagnostic to check your shoulder mobility.
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's how to reduce drag and become a smoother, faster swimmer.
Avoid pushing off right at the surface. Research shows that wave drag drops sharply even 0.5-1 meter below the surface.
That's why the underwater dolphin kick, sometimes called the "fifth stroke", is the fastest movement in swimming. It's also why FINA limits underwater swimming to 15 meters per start or turn.
However, don't stay underwater so long that you run out of air or lose momentum. 3 solid, powerful kicks are better than 10 sloppy ones. Return to the surface while you still have speed, not after you've stalled.

When your coach says "hold your streamline," here's what they mean:
This position reduces both form drag and frictional drag by keeping your body aligned like a torpedo.
The "Wall Test": Check Your Streamline at Home
You don't need a pool to fix your body line. Try this simple diagnostic test in your living room:
The Test: Can you keep your hands touching the wall without your lower back arching away from it?
If your back arches or your ribs pop out, you have a mobility restriction in your shoulders or thoracic spine. This drag will follow you into the water. Work on your dryland mobility to fix this limitation.
Drill 1: Push-and-Glide (The Distance Test)
This one needs a pool, but no instruction from a coach. Push off the wall in your tightest streamline (arms locked, head tucked, toes pointed) and count how far you travel before you slow to walking pace.
A reasonable recreational swimmer should comfortably reach 5–7 metres. Competitive swimmers often reach 10–12. If you're stopping at 3–4, something in your body line is creating drag: check the head, the arm lock, and the hip position.
Do this every session for two weeks as a deliberate check, not just a habit push-off. You'll feel the difference when it clicks, the glide extends noticeably and the water resistance drops.
Hint: keep your streamline under the water
Drill 2: Streamline Kick on Your Back
Swap one kickboard set per session for this: lie on your back in a full streamline position (arms overhead, ears between your biceps) and kick gently to move down the lane.
Why on your back? Because you can actually see what your arms are doing without lifting your head. You'll immediately notice if your arms drift apart, if your back arches, or if your head is pushing forward. It's also surprisingly good for shoulder mobility over time.
Start with a single 25 metres to get a feel for it. If your arms drift by the halfway point, your shoulders need work, the Wall Test will confirm it.
Your head should always follow your spine, not fight it.

Keeping your head aligned reduces turbulence and prevents drag-producing "bumps" in your body line.

In freestyle and backstroke, rotating your body side-to-side helps extend each stroke and align your body more effectively.
This rotation not only reduces form drag, but also engages your core muscles, giving you more power per stroke with less energy waste.
If you want to go even further and really maximize the drag removal. Here are a few more ways to do that.
Wearing a swimming cap smooths your head surface, reducing friction drag.
Paired with low-profile goggles, it helps your head cut through the water more cleanly, and keeps your hair from acting like a small parachute.

Yes, there's a reason competitive swimmers shave before big meets.
Less hair means smoother skin, less friction, and better hydrodynamics.
Shaving also gives a mental boost, that slippery "fresh skin" feel that makes you believe you're gliding faster (and often, you really are).
However, don't feel pressured to reach for the razor just yet. For 90% of swimmers, a good silicone cap and a tight-fitting suit will get you the majority of the drag reduction benefits. Save the shaving for your championship race!
Not all swimsuits are created equal.
Some high-tech suits reduce drag by compressing your body and minimizing water resistance.
It worked too well, FINA banned full-body suits after they helped shatter dozens of world records in a single season.
For everyday swimmers, a snug, sleek-fitting suit can still make a noticeable difference.
Most swimmers know what a streamline should look like. The problem is what actually happens underwater.
Here are the mistakes that show up most often, and what causes each one.
1. Head lifting out of alignment The single most common mistake. The moment your head comes up even slightly, it creates a bow wave in front of you, like pushing a wall through the water instead of a torpedo. In freestyle, this usually happens because swimmers try to look forward to navigate, or because they're anxious about what's ahead. Keep your head neutral: eyes looking straight down in freestyle, chin tucked, and let your spine lead.
2. Lower back arching This one is often invisible to the swimmer because it feels normal. An arched lower back pushes your hips up and your legs down, turning your body line into a slight "banana" shape that catches water on the way through. It's almost always a shoulder mobility issue, not a laziness issue, your shoulders can't reach overhead properly, so your back compensates. The Wall Test above will reveal this immediately.
3. Arms not fully locked together Hands that are slightly apart, or arms that drift shoulder-width instead of stacked directly overhead, create form drag on both sides. The hands should be overlapped (one on top of the other), thumbs locked, palms flat. If your hands separate during the glide, you're bleeding speed with every push-off. In other words, your head needs to stay locked by your arms, not moving around like a bell.
4. Hips dropping Hips that sit lower than your shoulders turn you into a slight ramp shape underwater. This is usually connected to the head position. If the head is up, the hips come down. Fix the head, and the hips often correct themselves. A tight core during the glide also helps keep everything level.
5. Feet not pointed Easy to forget, easy to fix. Flexed feet add drag at the back end of an otherwise good streamline. Point your toes and keep your big toes touching. It sounds like a small detail, and it is, but at the back of a long push-off it adds up.
The pattern behind most of these is the same: the problem usually starts at one end and travels to the other. Fix the head, the hips follow. Fix the shoulders, the back straightens. Start at the top.
It helps to visualize what forces slow you down during swimming and what you can do to make yourself a faster swimmer.

So there you have it, the science of swimming faster without swimming harder.
Reduce drag, perfect your streamline, and you'll glide farther with every stroke.
Whether you're chasing a personal best or just want to make swimming feel effortless, remember: the most efficient swimmer isn't the strongest, it's the one who creates the least resistance.
Now go make your inner broomstick proud and learn more about how your specific swimming style can be improved to reduce drag?
Streamline in swimming means positioning your body to move through the water with the least possible resistance, arms extended overhead, head tucked between your biceps, and body stretched straight from fingertips to toes. It is the most hydrodynamic position a human can hold in the water.
A streamlined body reduces drag and saves energy. It helps you swim faster, glide farther from each push-off, and maintain better efficiency across every stroke. In open water, good streamline also conserves energy over longer distances.
Arms fully extended above your head, one hand over the other with thumbs locked, biceps squeezed tightly behind your ears, head tucked with chin down, and body stretched in a straight line from fingertips to pointed toes. No gaps, no arching, no air pockets around the neck.
The most common mistakes are: letting the head lift (creates a wall of resistance), arching the lower back (breaks the body line), keeping arms too wide or not locked together, dropping the hips, and forgetting to point the toes. Most of these come from poor shoulder mobility rather than laziness.
Form drag (caused by body shape and position), friction drag (caused by water flowing over the skin), and wave drag (caused by the surface waves you generate while swimming). Wave drag is the largest factor and the one most directly improved by better streamline technique.
Three effective methods: the Wall Test at home (stand against a wall in streamline position and check for back arching), the push-and-glide drill (push off the wall in a tight streamline and count how far you travel), and streamline kick sets (kick on your back or stomach in streamline without a kickboard). Every push-off in practice is a chance to train it.
Focus on a tight streamline, push off underwater, keep your head aligned, and avoid unnecessary movements. Wearing a swim cap and smooth-fitting suit also helps reduce surface friction.
Shaving removes body hair that increases friction drag, and gives a psychological edge with a smoother feel in the water. For most recreational swimmers, a silicone cap and a well-fitting suit provide the majority of the same drag reduction benefits without reaching for the razor.
Yes. Wave drag is strongest at the surface. Pushing off 0.5–1 metre underwater eliminates most surface wave resistance and allows you to glide significantly farther before surfacing. This is why the underwater dolphin kick is the fastest movement in competitive swimming.
No. Every swimmer benefits from a better streamline, it makes swimming easier, reduces fatigue, and helps you glide more efficiently. In open water especially, good streamline conserves energy that matters when you are far from shore.
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