Fundamental Principles of Resistance Training
Improvements in muscular fitness occur only if the resistance training program is based on sound training principles and is prudently progressed over time (7, 21). Although factors such as your initial level of fitness, genetics, nutrition, and motivation will influence the rate and magnitude of adaptation that occurs, you can maximize the effectiveness of your resistance training by addressing three fundamental principles: progressive overload, regularity, and specificity.
The progressive overload principle states that to enhance muscular fitness, you must exercise at a level beyond the point to which your muscles are accustomed. This goes back to the idea of having to stress the muscle to get a positive response. Doing the same workout month after month will not maximize benefits. The principle of progression refers to consistently boosting the training stimulus or load at a rate that is compatible with the training-induced adaptations that are occurring (21). Following the principle of progressive overload requires that you provide your muscles with a new stimulus when they have adapted to the current overload. You can do this in a variety of ways:
- Increase the number of repetitions. Typically, 8 to 12 repetitions is recommended for muscular fitness (for middle-age and older adults starting exercise, 10 to 15 repetitions is recommended). People focusing on strength development may select fewer repetitions, whereas those focusing on muscular endurance may include up to 15 to 20 repetitions (1).
- Increase the number of sets for a given muscle group. You could do additional sets of the same exercise, or you could add another exercise that targets the same muscle group. For example, the chest muscles could be trained with two sets of the chest press or one set of the chest press and one set of the dumbbell fly.
- Increase the resistance. The increase in weight needed will vary depending on the exercise but is often prescribed according to the increments available (e.g., next-weight dumbbell, increasing by one plate on a weight machine).
When providing an overload, select one of these options at a time. Although you want to provide a new stress on the muscle, you do not want to overtax the muscle or supporting structures to the point of injury.
Although every training session does not have to be more intense than the last session, the principle of progressive overload states that the training program needs to be increased gradually over time to realize gains. For example, if you have been able to easily complete a given workout for a couple of exercise sessions, it may be time to make changes to provide an overload once again in order to keep the resistance training program fresh, challenging, and effective. If you are able to perform a given exercise for one or two repetitions over your target number for two training sessions in a row, this indicates that you are ready to increase the resistance while returning to the original target repetition range.
The principle of regularity states that exercise must be performed several times per week on a habitual basis to enhance physical fitness. Although training once per week may maintain training-induced gains, more frequent workouts are needed to optimize gains in health and fitness (1). In short, the adage “use it or lose it” is true because you will lose strength gains if you do not progress your program over time and perform resistance training on a regular basis (21). Although consecutive days of heavy strength training for the same muscle groups are not recommended, regularly training each major muscle group two to three times per week, with at least 48 hours separating training sessions for the same muscle group, is recommended to enhance muscular fitness.
The principle of specificity refers to the distinct adaptations that take place as a result of the training program. In essence, every muscle or muscle group must be trained to make gains in muscular fitness (see Human Body) for the location of the major muscle groups in the body). Exercises such as the squat and leg press can be used to enhance lower body strength, but these exercises will not affect upper body strength. What’s more, the adaptations that take place in a given muscle or muscle group will be as simple or as complex as the stress placed on them. For example, because tennis requires multi joint and multi directional movements, it seems prudent for tennis players to perform resistance exercises that mimic the movements of the sport. For tennis players who need strong leg muscles to move across the court, lunges are unbeatable exercises to improve lower body performance. Lunges performed in different directions actually simulate steps used in game situations.
The specificity principle can also be applied to the design of resistance training programs for adults who want to enhance their abilities to perform activities of daily life such as stair climbing and household chores, which also require multi joint and multi directional movements. For example, climbing stairs may be difficult as a result of poor lower body strength. By sensibly progressing from single-joint exercises such as leg extensions to multi joint exercises such as leg presses and dumbbell step-ups, you can improve your stair-climbing ability. These multijoint exercises specifically strengthen the quadriceps and gluteals, which are used in stair climbing.