Personal trainers, coaches, fitness enthusiasts and many other well meaning individuals completely misunderstand how our cardiovascular system works. There is simply no such thing as ‘cardio’. Medical Doctor Doug McGuff explains why. When someone uses the term ‘cardio’ it doesn’t matter how authoritative they are in the world of sport. They can be a world champion athlete or coach. Science simply doesn’t care. Furthermore, many beginners when taking up a new sport are grossly inefficient in motor skills for that discipline. They quickly tire. They then make the mistake of believing they need to run, cycle, swim, or workout more. Unless they have taken up running, they don’t need to run more. If they have taken up swimming, running more won’t make them better at swimming, They need to swim. This is a basic tenet of motor learning, a scientific discipline available as a qualification in many Universities. If you want to improve your endurance at BJJ or MMA, you need to practise that skill more. If you want to become physically stronger, you need a correctly designed strength training programme.