Training with free weights helps you to develop muscle strength, size and definition. Weightlifting also helps you to burn fat and improves your mood. Resistance training programs usually focus on working out one muscle group at least two times each week. Some programs work out one muscle group each day while other strategies group together chest with triceps, back with biceps or legs with abdominals. Before starting a resistance-training regimen please consult a physician.

Legs

The quads, hamstrings, glutes and calves are the primary muscle groups in your legs. Do barbell squats and barbell lunges to pack muscle mass onto your quadriceps muscles. To hit your hamstring muscles perform good mornings and Romanian deadlifts. One-legged cable kickbacks and barbell hip thrusts develop strength and definition in your glute muscles and standing calf raises develop muscle mass and definition in your calves. Do three sets of 10 repetitions for each exercise to develop strong, well-defined legs.

Chest

The pectoralis major and minor are the primary muscles in the chest region. Perform bench presses and decline bench presses to develop muscle mass and strength in your pectoralis major. Focus on your pectoralis minor muscles by doing weighted chest dips. Perform three sets of 10 repetitions for each exercise to develop muscle strength and size in your chest area.

Shoulders

The deltoid muscle, with its anterior, lateral and posterior heads, is the main muscle in the shoulder area. Perform seated military presses to target the entire deltoid muscle and do front barbell raises to concentrate on the anterior head of the deltoid. Do three sets of 10 repetitions to add muscle mass and strength to your shoulders.

Back

The latissimus dorsi and teres major muscles are the main muscle groups within the back. Do pullups, barbell pullovers and close-grip pulldowns to develop muscle strength, size and definition in your back muscles. Perform three sets of 10 repetitions to build up overall power in your back.

Arms

The biceps brachii, triceps brachii and forearms are the primary muscle groups in your arms. Do barbell curls to develop a peak in your biceps muscle. Perform lying triceps extensions to pack mass onto your triceps. Do barbell reverse curls to target your forearms. Do three sets of 10 repetitions for each exercise to build bigger, stronger arms.

Abdominals

The rectus abdominus is the main muscle in the abdominal region. Perform weighted crunches, incline situps and hanging leg raises to bring definition to your abdominal muscles. Do four sets of 20 repetitions for each exercise to develop core strength and tighter, leaner abs.