Final answer:
Cardio exercises strengthen the heart and lungs through increased heart rate and breathing rate.
Step-by-step explanation:
Answer:
If a form of exercise strengthens the heart and the lungs, it is classified as "cardio". This type of exercise is commonly known as cardiovascular exercise and includes activities such as running, swimming, and cycling. These exercises increase the heart rate and breathing rate, which helps improve the overall cardiovascular fitness.
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