How you choose will depend on what components of fitness you are targeting and your fitness goals. You can increase volume and intensity in a variety of ways: Increase the reps and sets of certain exercises, the weight you use, the number of workouts per week or per day, or decrease rest between sets, or any combination of those. Without it, your body has no added stimulus to adapt to, so you eventually reach a plateau, and your body says, “We’re good here.” Progressive overload is the increase in workout volume or intensity over time. In order to make progress-called “progression”-you need to follow the overload principle, or simply overload. And then it’s hard to improve your run time because your body is used to an overly specific training program. For example, if you only train to run 2 miles at a time, you’ll only be good at running 2 miles. Training to improve cardiorespiratory endurance also follows the SAID principle. In fact, the concept of specificity is where the guidelines for weight, set, and repetition come from for building muscular strength, endurance, and muscle hypertrophy. On the other hand, if you start a resistance-training program, you’ll get stronger.
If you stop exercising, you can lose lean muscle mass because your body doesn’t need to use energy to maintain muscle if you aren’t using it. As you change stressors to your body, it will change to meet the demands of those stressors. The SAID principle-Specific Adaptations to Imposed Demands, also called “specificity”-describes your body’s ability to adapt to physical demands. But you can overcome lack of progress by leveraging that very same ability to adapt. It happens because your body is very good at adapting to things over time. Whether you’re trying to get back into shape or advance to an elite level of fitness, loss of progress is a motivation killer. A stalled physical training program can be one of the most frustrating parts of working out.