Resistance training—also called strength or weight training—is an exercise technique used to improve health and athletic performance by building tendon and ligament strength; increasing muscle strength, tone, mass, and endurance; and enhancing bone density through repeated, consistent resistance exercise. You can use weight machines or free weights—like dumbbells, kettlebells, or medicine balls—or even your own body weight for resistance.

Resistance training programs typically involve a variety of anaerobic exercises that require a progressive increase in weight to increase the force of your muscle output. The number of repetitions and sets is dependent upon the goal of the exercise—building strength alone; increasing strength, mass, and endurance; or focusing mostly on endurance.

Weight training enables your muscles to contract with greater speed, which offers a number of health benefits. Not only does resistance training make you stronger, it can also improve metabolism and weight control, increase good cholesterol, and decrease your risk of osteoporosis. Furthermore, stronger muscles can help improve your posture and joint function, which reduces your risk of injury in everyday activities and at work.

Resistance training can also be used for rehabilitation from health conditions like injury, impairment, or surgery. For this kind of training, a physical therapist would design a resistance exercise program to address your specific needs and speed recovery.