If you are a collegiate, Olympic-level or professional athlete, you likely work with a strength coach who designs your workouts so that you achieve a peak level of fitness before the most important competitions on your schedule. The science of structuring workouts to peak at a specific time is known as periodization and has been a key component of successful athletes for decades.

Here’s an example of a periodized program for professional American football players: Train to be in football shape before training camps begin in late July and peak at the highest level of fitness when teams are making a push for the post-season playoffs in late November. Once a professional football team has completed its season, the athletes have a period of weeks of light, non-football specific activity before starting the conditioning program to prepare for the next season.

Exercise is physical stress applied to the body; the specific stresses applied and the amount of recovery after each workout are important factors in achieving a desired fitness outcome. Top strength and performance coaches know that bodies get stronger in the recovery period after the workout, not during it. Therefore, they use alternating periods of low-, moderate- and high-intensity exercise to ensure that athletes are properly recovered before entering a competition.

Even if you’re not up for a pro contract or college scholarship, or competing for a gold medal, you can use periodization to achieve your personal fitness goals. Here are six things to know about how periodization can help you design an exercise program that delivers results, along with some ideas for how you can create your own periodized year-long workout plan.

1. An exercise program is comprised of specific variables that determine the type and amount of stimulus applied to the body: exercise selection, intensity, repetitions, rest interval, sets and speed of movement, or tempo. It is well established that physical adaptations to an exercise program, including muscle definition and size, depend on the application of these variables. Systematically changing these variables allows you to alternate between high- and low-intensity workouts, ensuring that your muscles receive the appropriate amount of recovery after each exercise session.

2. Periodization alternates phases (periods) of training based on volume, intensity and movement complexity. The greatest benefit of periodization is that it uses rest to allow for adaptation to the physically demanding stresses of exercise. Structured, consistent changes to an exercise programs that adjust for training intensity allow you to maximize results while minimizing the risk of injury or becoming stuck on a plateau.

3. Intensity is the actual amount of weight used in a program, which can be anything from body weight to heavy weights that allow only one or two reps at a time. When training intensity is low, the volume in terms of reps and sets can be high. As training intensity becomes more challenging, the number of reps should be reduced while increasing the length of the rest interval or the number of sets. The purpose of periodization is to manage the application of physical stress applied to the body by adjusting the intensity of the exercises on a regular basis.

4. Resistance training causes two specific types of stress on muscle tissue: metabolic and mechanical, both of which provide the stimulus required to grow muscle and increase definition. A properly periodized program can alternate between phases of heavy weight for low reps to create mechanical stress and phases of light-to-moderate weight for high reps to induce metabolic stress. The goal is to manipulate the variables of the exercise program to create either metabolic fatigue, mechanical overload or a combination of the two that will initiate the desired physiological adaptations.

5. The body will adapt to a specific stimulus after a period of approximately eight to 12 weeks; therefore, to help your body make continual changes, it’s necessary to adjust your workouts every two to three months.

6. Creating a periodized program can be as simple as switching the types of exercise equipment you use from body weight to dumbbells to kettlebells to barbells to sandbags—you get the idea. You can keep everything else the same, but changing the type of equipment used will provide a sufficient stimulus for making changes to the body.

What follows is a sample periodized plan you can follow. There are four seasons in a year, each lasting approximately 12 to 13 weeks, which is about the optimal amount of time the body requires to adapt to an exercise stimulus.

January to March

General Goals

• Foundational preparation for swimsuit season, or
• Follow a body-building-type protocol like this Arnold Schwarzenegger designed workout to focus on muscle growth and definition.
• Prepare for favorite spring/summer-time outdoor activities
• Follow a program to improve cardiorespiratory efficiency and structure integrity for endurance activities or explosive power for sports like soccer, lacrosse or rugby.

April to June

General Goals

• Final prep for swimsuit season, or
• High-volume training with moderate-intensity weights to maximize muscle growth.
• Start participating in favorite activities
• Regardless of what your favorite activity might be, you should still do some type of conditioning program to maintain muscle mass and force output.

July to September

General Goals

• Enjoy your favorite outdoor activities or bask in the adulation of having one of the "hottest" bodies at the beach.
• Training program should focus on muscle isolation and body-building techniques to promote rapid muscle growth.
• Enjoy your favorite summer-time activities. Plan for two to three high-intensity workouts a week; on the other days use low-to-moderate intensity.
• High-intensity Interval Training (HIIT) can be extremely effective for achieving results, but it’s important to only do a few times per week to avoid potential injuries causes by overtraining.

October to December

General Goals

• Top performing athletes don’t try to maintain peak fitness throughout the year and neither should you—consider this your "off season." If you worked hard all summer, consider this your "offloading" phase and use lighter weights and focus more on improving stability and mobility than working at a high intensity. Working at a lower intensity does not mean skipping all exercises—active recovery workouts are perfect for this phase of training.
• Another option for this time of year is to prepare for your favorite winter sport(s). Don't wait until the week before your big ski trip to start training for it—the earlier you can start preparing (October at the latest), the more fun you will have participating in your favorite activities