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Sports Science

Swimming: Into the Deep End

You've thought about it. Maybe for triathlon, maybe for cross-training, maybe because your physio said so. Here's what getting into swimming actually looks like — from someone who can barely do a length.

There's a specific kind of humbling that happens when a fit runner gets into a pool for the first time. You can run a half marathon. You can hold a 5:00/km pace for an hour. And then 50 metres of front crawl leaves you gasping at the wall like you've never exercised in your life.

Welcome to swimming. Your cardiovascular fitness means almost nothing here. Let’s talk about why — and how to start without drowning your ego.


Why swimmers are different

Running is intuitive. You’ve been doing it since you were two. Your body knows how to move through air. Swimming is the opposite — you’re in a dense, unfamiliar medium where technique is everything and fitness is almost nothing.

~90%
Running efficiency
~3-5%
Beginner swim efficiency
~10%
Good swim efficiency

A beginner swimmer wastes 95% of their energy fighting the water instead of moving through it. That’s why you’re gasping after 50 metres — you’re not unfit, you’re just incredibly inefficient. Your engine is fine. Your boat is shaped like a brick.

lightbulb The good news

Because beginners are so inefficient, small technique improvements produce massive gains. A few weeks of focused drill work can cut your 100m time by 20-30 seconds — without getting any fitter. You're just wasting less energy.


The three things to fix first

Forget training plans. Forget intervals. Forget counting laps. If you’re starting from scratch, fix these three things and everything else follows.

1. Breathing

The number one reason adult beginners struggle. You’re holding your breath, lifting your head to breathe, and your legs sink every time you turn your face.

The fix: exhale continuously underwater through your nose. When you turn to breathe, your lungs are already empty — you just inhale. No gasping, no head lifting, no panic.

Flotti thinking
Flotti

Breathing in swimming is backwards from everything else. On land, you inhale actively and exhale passively. In water, you exhale actively and inhale is just... opening your mouth. Your brain hates this. It takes practice.

2. Body position

Your body should be horizontal — not angled with your head up and feet dragging. Think of being pulled forward by your chest, not pushed from behind by your legs.

Look at the bottom of the pool, not forward. Press your chest slightly into the water. Your hips and legs rise. Suddenly you’re gliding instead of ploughing.

3. Don’t kick so hard

Beginners kick like they’re sprinting in the water. Big splashy kicks that burn energy and create drag. A good swimming kick is small, fast, and comes from the hip — more like a flutter than a stomp. For distance swimming, the kick is barely there.

warning The runner's instinct

Runners try to power through the water with effort. Swimming rewards the opposite — relaxation and length. The less you fight the water, the faster you go. This takes weeks to internalise and feels deeply wrong at first.


What swimming gives a runner

Once you can do 20-30 continuous minutes without stopping (which takes most adults 4-8 weeks of consistent practice), swimming becomes a genuinely useful cross-training tool:

Upper body and core work. Running barely uses your arms and lats. Swimming hammers them. You’ll build functional upper body strength and core rotation that helps your running posture in the final kilometres of a long race.

Active recovery. Water supports your bodyweight — no impact, no gravity, no compression on joints. An easy swim the day after a long run flushes your legs better than lying on the couch.

Breathing efficiency. Swimming teaches you to manage your breath under stress. Controlled exhalation, efficient inhalation, comfort with oxygen debt. This translates directly to hard running efforts.

pool Illustration: runner in the pool — different muscles, same aerobic system

A starter plan

If you can currently swim a length (25m) without stopping, here’s a simple 4-week ramp:

WeekSessionTotal distance
Week 14×50m with 30s rest between. Repeat 3-4 times~600-800m
Week 24×100m with 20s rest. Mix in 4×25m drill (catch-up or fingertip drag)~800-1000m
Week 32×200m steady + 4×50m with focus on breathing~1000-1200m
Week 4400m continuous + 4×100m with 15s rest~1200-1400m

Swim 2-3 times per week. Focus on technique over speed. Count your strokes per length — fewer is better. A good target for a 25m pool is 16-20 strokes.

tips_and_updates The drill investment

Spend 20% of every swim on drills — catch-up, single-arm, fingertip drag, kick with board. It feels like wasted time. It's the fastest path to better technique. A month of drills beats a year of grinding out ugly laps.


The triathlon question

If you’re reading this thinking “maybe triathlon?” — you’re not alone. Running + cycling + swimming is the obvious progression. And swimming is the part that scares people most.

Flotti
Flotti

A sprint triathlon swim is 750m. If you can swim 1000m continuously at an easy pace, you're ready. That's achievable in 6-8 weeks from zero with consistent practice. The swim is the shortest leg — don't let it be the reason you don't sign up.

The swim leg of a sprint triathlon takes most age-groupers 15-20 minutes. You spend more time than that warming up for a run. The barrier is mental, not physical.


The takeaway

Swimming is hard at first because technique matters more than fitness. Fix breathing, body position, and kick — then the distance comes naturally. For runners, it's zero-impact cross-training that builds upper body strength, breathing control, and recovery. Start with drills, not distance.

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