Muscular strength and endurance are developed by the overload principle – increasing the resistance or workload to levels above those normally experienced. The exercise load can be weights, resistance equipment, or your own body such as pull-ups, push-ups, sit-ups, etc. You can also increase the load by increasing the number of repetitions of an exercise.

The American College of Sport Medicine recommends the following guidelines for strength training:

Key components of a good strength-training program

·    Choose 8-10 separate exercises that train the major muscle groups of the body (arms, shoulders, chest, abdomen, back, hips, and legs).

·    Do 8-12 repetitions of each of these exercises to the point of mild fatigue. Be careful not to overdo, especially when first starting. Older person should use lighter weights but do more repetitions (10-15). This puts less strain on the body. When the exercise becomes easy, increase the weight or resistance, or increase the number of reps.

·    Do these exercises 2 to 3 days each week for best results.

·    Use proper technique for each exercise. Have an experienced instructor demonstrate good technique for each exercise. Do each exercise in a controlled manner (not fast or jerky).

·    Perform each exercise through a full range of motion.

·    Maintain a normal breathing pattern. Don’t strain and hold your breath when lifting, doing pushups, etc.

·    If possible, exercise with a training partner who can provide feedback, assistance and motivation.

References
American College of Sports Medicine, Guidelines for Exercise Testing and Prescription, "Muscular Fitness",  6th Edition, Lippincott Williams, & Wilkins, 2000