Which principle of exercise training states that the body needs to be stressed to improve physical fitness?

The best way to achieve optimum results in exercise and fitness is to follow a plan. But not just any plan, such as “I’m going to run 5 miles every day” or “I’ll lift the heaviest weight I can every time I work out.” Your body is an amazing machine that responds to specific stimuli in distinct ways, and your brain is constantly working to protect the body from threats – like way too much stress on the muscles and tendons from continuous all-out hard exercise.

Principle (noun): 1. a basic truth or theory;  2. an idea that forms the basis of something;  3. a law or fact of nature that explains how something works or why something happens.

Fortunately, exercise science gives us five basic principles we can incorporate into a fitness program that will develop the changes, or “adaptations” we desire, in a safe and lasting way. These five principles are:

• The Overload Principle
• The F.I.T.T. Principle
• The Specificity Principle
• The Rest and Recovery Principle
• The Use It or Lose It Principle

The Overload Principle and the F.I.T.T. Principle work together, so let’s review these first.

The Overload Principle is considered the most important concept in exercise. In simple terms, it means that your body will adapt to the demand you impose on it. For example, when you lift a heavy weight you haven’t lifted before, or you complete a hard cardio workout that puts new demands on your heart and lungs, physiological changes will take place that will allow you to do this more easily next time.

Because the body is so adaptable, the demands we put on it must gradually and progressively increase over time in order to achieve long-term fitness gains. These demands must be applied slowly, because too much too fast causes the body to react negatively to excessive stress. (For more about this concept, read The Body’s Response to Stress – Understanding the General Adaptation Syndrome.)

So it’s important to strategically vary your mode of exercise, intensity and duration of training in order to get better, stronger or faster. This is where the F.I.T.T. Principle comes in.

F.I.T.T. stands for Frequency, Intensity, Time and Type. These are the four areas where increases in workload or demand can be made in order to progressively overload the body so it adapts in the desired way.

Frequency means how often an exercise is performed. After any kind of exercise, your body begins a process of repairing and rebuilding stressed tissues. It’s important to find the right balance of work and recovery that provides just enough stress for the body to adapt as well as recover for the next session.

Intensity is the amount of effort or work completed in a specific exercise. For example, walking at a conversational pace is low intensity, whereas sprinting for 400 yards is high intensity. In strength training, factors that influence intensity are the weight itself (load), the number of sets and repetitions, the tempo of the repetitions, and whether a level of instability has been added (such as standing on one leg while doing shoulder presses.) Once again, just enough intensity to overload without overtraining, injury or burnout is what’s important here.

Time is simply the duration of the exercise session. It’s a function of intensity and type.

Type means the type of exercise performed – strength training, cardio, or a combination of both. The type of exercise is tied to the Specificity Principle, discussed next.

This table illustrates how to combine the Overload Principle and the F.I.T.T. Principle for strength training or cardiovascular training:

The Specificity Principle is, quite simply, that the exercise you do should be specific to your goals. For example, if your goal is simply health and weight management, focus on total body strength, cardio and a healthy diet. If you are a runner wanting to improve your race times, include speed workouts in your training. If you’re a cyclist training for a 100-mile ride, focus on building up longer distance training rides at an endurance pace.

The Rest and Recovery Principle is critical to achieving gains in fitness. The body simply cannot tolerate too much stress, and over time will instead “shut down” in order to protect itself. This results in overtraining syndrome, burnout, excess fatigue, and a weakened immune system. (Read The Body’s Response to Stress – Understanding the General Adaptation Syndrome.) Exercising every day is perfectly fine – just not the same exercise at the same intensity. Especially with strength training, it’s important to allow at least a day between sessions to allow muscles to repair and rebuild. However, working different muscle groups on different days (what’s called a “split routine”) will allow for this recovery period for one muscle group while working another. Low intensity cardio can be done every day, but rest between intense sessions. Rest and recovery are important for your mental state too!

The fifth principle, while not specifically targeted to fitness adaptations, is still important to be aware of – Use It or Lose It. Most everyone is aware of this concept at some level, as it applies to many things in life. With respect to the body, muscles build strength (called “hypertrophy”) with use, and lose strength (“atrophy”) with lack of use. This includes not only the skeletal muscles, but also the heart and even the brain (although it’s not technically a muscle.) How quickly atrophy occurs is dependent on many factors, and will be the subject of a future blog post.

Incorporating these principles into your fitness routine will ensure you get the best results in the most efficient way, while preventing injury and overtraining.  But it can be complicated. As a virtual fitness coach and personal trainer certified through the National Academy of Sports Medicine (NASM), I have the knowledge and experience to develop a progressive program specifically designed for you and your fitness goal. We’ll work together, on your schedule, to get you where you want to be, safely and effectively. Contact me today for a free consultation!

The overload principle is a deceptively simple concept. To make fitness gains you have to overload the body progressively. Lift heavier weights, run longer, workout more days a week, and so on in order to provide enough stress that the body will adapt and get stronger, faster, and more powerful.

As a trainer you surely know what the overload principle is, but do you really understand it? Enough to plan the best program for each client? We’ll run through the basics of overload and provide some important tips for progressively and safely overloading your clients until they hit their goals.

What is the Overload Principle?

The overload principle is one of the seven big laws of fitness and training. Simply put, it says that you have to increase the intensity, duration, type, or time of a workout progressively in order to see adaptations. The adaptations are improvements in endurance, strength, or muscle size.

In other words, when a client first starts working out, from having been previously mostly sedentary, they will see some quick gains. But, as they get fitter, you will need to increase the intensity of their training to continue to see those gains. If they continue lifting the same weights for the same number of sets and reps, week after week, the body will have adjusted to the stress, there will be no more adaptations and they will plateau.

Issues with the Overload Principle

Overloading is necessary to make gains in fitness and athletic performance. However, there are some important issues associated with this principle, both what can happen if you don’t do it at all and if you don’t do it right.

Hitting a Plateau while Ignoring the Overload Principle

The obvious issue with ignoring the overload principle is the failure to make gains. If you continue to do the same workout or train at the same intensity and frequency, you will make gains only to a certain point. After that you are not overloading the muscles and hit a plateau with no further improvements or adaptations.

This happens because our bodies are very good at adapting to stress. Initially for your newbie client, that five-pound weight provides a good amount of stress. The client gets stronger quickly. But over time, the level of stress needed in order to make new adaptations rises so high the five-pound weights just don’t cut it.

Overreaching and Overtraining Stress

On the other hand, if you use the overload principle in the wrong way, say by increasing intensity too quickly, you get into a state of overreaching or overtraining. Overreaching is a short-term problem, a decrease in physical performance that takes days to overcome.

Overtraining is a more sustained period of excessive training stress. It can take weeks to months to recover from this state of decreased performance. Some signs of overtraining you should watch out for include:

• Increased resting heart rate.

• Increased blood pressure.

• Loss of appetite and weight loss.

• Difficulty sleeping.

• Emotional changes or mood swings.

• Fatigue.

• Chronic muscle soreness.

• Extended recovery times.

Strategies for Overloading

There are several ways you can make sure your client is overloading and not hitting a plateau. Essentially these strategies all involve increasing some factor of a workout. You can increase one, two, or more in a way that makes sense for your client’s goals. These different factors together make up what is known as the FITT principle:

• Frequency. Frequency is the number of times your client works out, usually measured per week. Increasing frequency could mean going from one to two lifting sessions per week, for instance.

• Intensity. This is how hard your client is working during a training session. For strength training you can increase intensity by using progressively heavier weights. In aerobic activities, measuring heart rate is a good way to monitor increasing intensity.

• Time. The time spent doing a particular exercise, like lifting or running, can be increased to progress and overload.

• Type. Type refers to the actual, specific exercise your client is doing. You can vary the exact type of strength exercises, for instance, to overload a particular muscle or muscle group. For instance, add leg presses to squats to overload leg muscles.

It’s important to vary the factors that you change for your client. For instance, one day you may focus on increasing intensity by using heavier weights. In the next session try to focus on another strategy, like increasing the time spent on weights.

For aerobic adaptations, for instance for a client who is a runner, work on intensity one day, using heart rate or interval training, and increase time with a long slow run on another day in the same week. Mixing up how you overload the body can help to minimize the risk of hitting a plateau on gains.

Rules for Safe and Gradual Overloading

Overloading should always be progressive and gradual. Increasing intensity, reps, frequency, and other elements of training too quickly is dangerous. It can cause injuries, lead to muscle soreness, and of course cause overtraining. Follow these guidelines when planning overload for your clients to keep it safe and progressive:

• It is essential that progression occurs gradually. You can’t go from five-pound weight bicep curls one week to 20 pounds the next without increasing the risk of injury and overreaching or overtraining. Make a careful plan for how to increase workout factors that is not too abrupt.

• For strength training, work on form before moving on to a bigger weight. A safe way to progress with weights is to start with upping time and frequency before intensity. Once your client has mastered a particular movement with safe, good form, start slowly increasing the weight for more intensity.

• Test your client’s maximums to decide on weight amounts and appropriate increases in intensity.

• It’s also important to keep a log of training sessions and how you are increasing frequency, intensity, time, and type.

• Plan for recovery time. This is when gains happen and it helps avoid overtraining and injury. Recovery can be an active rest day, with a gentle workout like a walk, but it can also involve alternating easy and hard workouts.

• Don’t let your client burnout when training. Working out to collapse or exhaustion is never healthy and is more likely to lead to overtraining.

To learn more about how to determine rest periods between high-intensity sets, check out this post on the ISSA blog.

Applying Periodization

One way to avoid overtraining from overloading is to apply periodization to your client’s workouts. To get results from overloading, you don’t actually want your client to progress linearly. It is not a good idea to simply make every workout harder, faster, or longer than the previous one. There should be more variation, which is the idea of periodization in training.

Periodization is the specific planning of training cycles. It is a necessary way to train to accommodate the overload principle. In order to progress and make gains you have to vary workouts to overload the body. But, you also need to accommodate the GAS (general adaptation syndrome) principle, which says high-intensity training needs to be followed by low-intensity training or rest.

By periodizing training, you can plan for progressive overload with cycles of more intense, frequent, longer workouts and cycles that are lower in intensity for recovery and rest. There are three types of cycles that go into a periodized training plan:

• Macrocycles. The macrocycle is a long period of training, lasting six months to a year. The macrocycle may coincide with a sports season, like summer and fall running races, or culminate in one event, like a fitness competition. Your client will have large, overarching goals for the macrocycle, like running a marathon in a certain time.

• Mesocycles. A macrocycle is divided into three to four mesocycles, lasting a couple of weeks to a month. These cycles can hit specific smaller goals, like running a 10k, then a half marathon. They may focus on specific aspects of training, like strength or hypertrophy for lifting.

• Microcycles. These shorter cycles last just about a week but maybe two weeks. Each microcycle is the detailed workouts you plan for your client, keeping the larger goals and focuses in mind.

Periodization allows you to vary your client’s overall workout and take advantage of overload with appropriate periods of rest or low intensity activities. Changing up the focus of each mesocycle and varying sessions within each microcycle provides enough overload, variation, and recovery time to help meet the overall macrocycle goals.

The overload principle is a crucial, foundational idea in fitness. If you don’t overload the body, you will never see gains in muscle strength, endurance, and size or aerobic fitness. Over-stress the body and you will over-train and see a decline in performance or even get injured.

Finding the right balance is essential for careful and effective progression. And when combined with periodization in a good training plan, you can help your clients overload the right way, making important fitness gains and hitting athletic and performance goals.

If you want to learn more about working with athletes and helping them hit their goals, check out the ISSA’s comprehensive course on Strength and Conditioning.

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