What is the definition of "weight training"?

According to Mayo Clinic, weight training refers to a type of strength training that involves the use of weights for resistance. Weight training does not only tone muscles, but also improves physical appearance and prevents age-related muscle loss.

Mayo Clinic explains that this type of training applies stress to the muscles, which makes them adapt and become stronger just as aerobic conditioning can strengthen the heart. Moreover, weight training can be done with the use of weight machines or free weights, such as dumbbells and barbells. The strength of a person can be significantly improved if he performs 20- to 30-minute weight training sessions two or three times a week.