How to Improve Freestyle Swimming When You Come From Running
You can run 10 km without pushing, but after 50 m of freestyle you're clinging to the wall, out of breath. The studies don't cover runners. They compare triathletes with swimmers, and they show where the water slows you down.
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The short answer
The data comes from triathletes, not beginner runners. In a 2025 study of 8 triathletes and 10 swimmers, published in the Journal of Functional Morphology and Kinesiology, triathletes moved forward less with each stroke, and their 200 m time was linked to passive drag (r = 0.68 to 0.86). Work on your position and glide first.
Key takeaways
- In a 2025 study, the triathletes did not move their arms more slowly than the swimmers. They moved forward less with each stroke.
- Head position and body alignment reduce water resistance, so the effort needed for the same speed goes down.
- In elite swimmers studied, max heart rate was lower in the water than when running. Don't set your swim workouts with your running zones.
- World Triathlon and USA Triathlon rules allow any stroke. Breaststroke is permitted in a race.
You can hold a pace for an hour and manage your breathing and fatigue. Then you get in the water, and after two lengths everything falls apart: your heart races, your legs sink, and you want to stop.
No study has followed runners learning freestyle. But research comparing triathletes with swimmers shows what sets them apart. That gives you a lead to work on: reduce drag before you push harder.
What the triathlete study shows
A study published in 2025 compared 18 men: 10 swimmers and 8 triathletes. The swimmers had higher speed, longer strokes, and a better swimming efficiency index. Only one variable did not separate them: stroke rate, meaning the number of arm movements per minute.
Triathletes did not move their arms more slowly. They moved forward less with each stroke, and their passive drag was higher.
A word of caution: triathletes averaged 36 years old, swimmers 21, and all participants were men. These results do not describe beginner runners. They point to a direction: before moving your arms faster, try to reduce drag.
Reduce drag first
In the same study, among the 8 triathletes, times over 200 m and 25 m were linked to passive drag (r = 0.68 to 0.86) and to power (r = -0.58 to -0.80). This is an association, not a cause. The authors still draw a guideline: target drag reduction and propulsive power.
Head position
Researchers towed 10 regional-level swimmers underwater, without them swimming, to measure resistance. With the head low and aligned, arms overhead, passive drag dropped by 10.4 to 10.9% compared with a raised head. With arms along the body, it dropped by 4 to 5.2%.
These measurements cover gliding, not full strokes. They give you a simple direction: look toward the bottom of the pool, keep your neck relaxed, and keep your head in line with your body.
Stroke length or stroke rate
Since stroke rate did not separate the swimmers from the triathletes in the study, there's no reason to windmill your arms. Coaches recommend counting your strokes per pool length, then trying to take one fewer while holding the same pace.
Heart rate in the water: don't rely on your running zones
Among 12 elite swimmers, max heart rate averaged 6.7 bpm lower when swimming than when running (199.9 when running).
If you set your watch by your running zones, you may misjudge your effort in the water. Rely on a reference pace instead, and use how you feel to complete the picture.
Structure your workouts: drills and the 200 / 400 test
A workout can be built in three blocks: an easy warm-up, a few short drills to feel the glide, then a set at a controlled pace. Coaches use drills a lot (single-arm swimming, catch-up, kicking) to learn position. Studies have not compared them with each other: they are coaching tools, not proven methods.
To find your reference pace, do a critical speed test: a timed 200 m and a timed 400 m, with recovery between them. The calculator turns these two times into a pace per 100 m.
Free calculatorSwim pace (CSS)Open the calculator →Note your pool length (meters or yards) along with your times, so you can compare similar workouts.
From the pool to open water: what the rules say
In open water, there's no wall and no lane line on the bottom. On the rules side, you have more freedom than you might think.
World Triathlon (art. 4.1) and USA Triathlon (art. 3.1) word it almost the same way: the athlete may use any stroke, swim in place, or float. They may also hold a fixed object, such as a buoy, to rest. USA Triathlon specifies that it must not be used to move forward. Freestyle is therefore not mandatory.
What you can do at your next workout
- Do your 200 m / 400 m test before setting your paces, and note the pool length.
- Look toward the bottom with your head in line with your body for the whole warm-up.
- Count your strokes over 25 m, then try to take one fewer at the same speed.
- Don't train by your running zones: in the trained swimmers studied, heart rate was lower in the water. Your gap may be different.
- Keep the warm-up easy: you're here to learn, not to empty the tank.
ELYO reads your swim workouts from your watch and tracks your pace, heart rate, volume, and consistency from one week to the next. It then adjusts your training plan with your running in mind, so the pool doesn't cut into your runs.
Frequently asked questions
Why can I run 10 km with no problem but get out of breath after 50 m of freestyle?
The studies don't cover runners. In triathletes, swim time is linked to drag: a misaligned body costs effort to move forward. Ease off, look toward the bottom, and lengthen your glide before trying to go faster.
Can I swim breaststroke during a triathlon?
Yes. World Triathlon and USA Triathlon allow any stroke, as well as swimming in place or floating. You can also hold onto a buoy to rest, as long as you don't use it to move forward.
Is a wetsuit mandatory, and at what temperature?
It depends on the water temperature and the race rules. World Triathlon bans wetsuits from 22 °C (age-group categories, up to 1,500 m) and requires them at 15.9 °C and below. Check the rules for your race.
My heart rate is lower when I swim: how should I set my zones?
Don't reuse your running zones. Among 12 elite swimmers, max heart rate averaged 6.7 bpm lower when swimming, and your gap may be different. Do a 200 m / 400 m test, train with a reference pace, and keep heart rate as a complementary guide. If your heart or your breathing worries you, talk to a doctor.
Sources
- Assíria-Costa L. et al. (2025). Comparison of the Hydrodynamic Profile Between Competitive Triathletes and Swimmers. Journal of Functional Morphology and Kinesiology, 11(1):10. DOI
- Cortesi M., Gatta G. (2015). Effect of The Swimmer's Head Position on Passive Drag. Journal of Human Kinetics. Article
- Maximal Heart Rate for Swimmers (2019). Sports, 7(11):235. DOI
- World Triathlon (2025). World Triathlon Competition Rules, edition of December 13, 2025, articles 4.1 and 4.2. Rules
- USA Triathlon (2025). USA Triathlon Multisport Competition Rules, version of March 28, 2025, article 3.1. Rules
Written with the help of AI.
