Cardiovascular fitness training requires lots of energy. This energy comes in the form of carbohydrates, and you must consume a sufficient amount to meet your requirements. I will be going in to greater detail in the future but until then use this as a guide:
If you are exercising 1 hour per day, consume 5 times your bodyweight (kg) in grams.
eg. If you weight 50kg, you must consume 250g of carbohydrates per day
If you are exercising 2 hours per day, consume 7 times your bodyweight (kg) in grams
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