Câu hỏi:

Read the passage and choose the best option A, B, C or D to answer the question.   

Along with jogging and swimming, cycling is one of the best all-round forms of exercise. It can help to increase your strength and energy, giving you more efficient muscles and a stronger heart. But increasing your strength is not the only advantage of cycling. Because you‘re not carrying the weight of your body on your feet, it‘s a good form of exercise for people with painful feet or backs. However, with all forms of exercise it‘s important to start slowly and build up gently. Doing too much too quickly can damage muscles that aren‘t used to working. If you have any doubts about taking up cycling for health reasons, talk to your doctor and ask for his/her advice.  Ideally you should be cycling at least two or three times a week. For the exercise to be doing you good, you should get a little out of breath. Don‘t worry that if you begin to lose your breath, it could be dangerous and there must be something wrong with your heart. This is simply not true; shortness of breath shows that the exercise is having the right effect. However, if you find you are in pain then you should stop and take a rest. 

People with back problems might go cycling because__________.