For that reason, full extension of the knee and active quadriceps exercises were avoided.

出于这个原因，被避免做充分延长膝关节和股四头肌主动练习。

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You can improve your health by training with free weights or doing exercises that will build up your quadriceps and protect your knees.

通过重量训练或做运动来锻炼出四头肌和保护膝盖，从而使得你自己更加健康。

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The two main exercises for quadriceps include leg extensions (usually done on an exercise machine) and squats.

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