Swimming

How swimming burns calories

Water is roughly 800 times denser than air, so every stroke pushes against real resistance the whole way through. At the same time, your body works to stay warm in water that's almost always cooler than your skin, adding to the energy cost beyond the movement itself.

At 8.3 MET, swimming sits just below running in burn rate, but spreads the effort across your arms, legs, and core simultaneously rather than loading mainly your legs.

What changes the real number

• Stroke choice: butterfly and freestyle at race pace cost far more than an easy breaststroke or backstroke
• Water temperature: colder pools increase the energy your body spends on staying warm
• Technique efficiency: a more efficient stroke moves you further per stroke, which changes total cost at a given pace
• Rest at the wall: frequent stops between lengths lower the average burn rate compared to continuous laps

Technique notes

• Keep your body as horizontal as possible in the water — a dropped hip or low kick creates drag that costs energy without adding speed
• Exhale fully underwater so each breath is quick and doesn't break your rhythm
• Rotate from your core on freestyle and backstroke rather than pulling with the arms alone
• Build lap volume gradually — swimming fatigue often comes from technique breakdown, not just muscular tiredness

How it compares