Can you improve your cardio fitness playing sports?
Hell yeah!
In fact I think it’s probably the best way to improve your cardio fitness for two reasons:
It’s Enjoyable
Pounding a treadmill or playing an exhilarating sport? Erm.... it’s a no-brainer right?
It’s Specific
If you want to get fitter for a particular sport your best bet is to play that particular sport. This challenges your muscles and energy systems in the most sport-specific way possible and creates training adaptations perfectly aligned with your goals. This is why seasoned cyclists don’t instantly make good long distance runners. They are cycling fit but not running fit.
So yes, you can absolutely improve your cardio fitness playing sports. The type of sport and level of intensity you play at will dictate the extent of your improvements.