Interval Training for General Health

In researching exercise methods for weight loss, general fitness, and improving overall health, you may have come across a form of exercise called interval training. A search about interval training will lead you into a somewhat confusing maze of acronyms , protocols, percentages, and forums full of people with varying opinions.

There are tremendous benefits to interval training, and we hope to simplify exactly what it is, explain how you can benefit from it, and how it can be incorporated into your exercise routine. So, let’s start with what interval training actually is.

What is interval training?

Think of interval training as an umbrella term for a type of exercise that involves alternating levels of effort for set durations of time. Under the umbrella of interval training are numerous protocols of varying intensities and interval lengths. Some popular protocols you may have heard of include:

• Tabata Training: Alternating between 20 seconds of vigorous activity and 10 seconds of rest
• Norwegian 4x4 Protocol: Alternating between 4 minutes of vigorous activity and 3 minutes of active rest
• 30-20-10 Training: 30 seconds of light exertion, 20 seconds of more intense exertion, and 10 seconds of all-out effort
• Sprint Interval Training (SIT): 20-30 seconds of maximal effort followed by 4-5 minutes of recovery

Isn’t that the same as a HIIT workout?

HIIT stands for high intensity interval training, which is a broader term that includes most interval training, including the ones listed above. There are some protocols for low intensity interval training, but for the most part “HIIT” and “interval training” are used interchangeably.

What qualifies as “high intensity”?

This is where some of the confusing terminology comes in, and where we hope to provide some clarity. There are two main methods in which “high intensity” exercise is defined. They are the Heart Rate Method and the RPE or Relative Perceived Exertion method.

Heart Rate Method:

This method uses (you guessed it) your heart rate to determine the level of exertion you are achieving during a workout. As a general rule, a person’s maximum heart rate (HRmax) is calculated by taking 220 and subtracting your age. For example, a 40-year-old would have a presumed maximum heart rate of 180 beats per minute (220-40) during intense exercise. This means that during the absolute maximum effort (sprinting on a track or pedaling as fast and hard as possible on a bike) a normal 40-year-old’s heart would be able to beat at around 180 beats per minute. Using this rule, most exercise physiologists classify any exercise that achieves roughly 80-95% of your max heart rate as high intensity. For our 40-year-old, this would mean he or she would be aiming for a heart rate between 144-171 during their exertion phase, followed by a period of rest.

Relative Perceived Exertion (RPE):

This method relies entirely on how you are feeling during exercise and considers factors like: Are my muscles burning? How hard am I breathing? How much am I sweating? How tired am I?

As you can imagine, it is a very subjective form of evaluation but with some practice it can become pretty reliable. There are two scales used to define RPE, but the simplest one uses a standard 0-10 scoring system. An RPE of 0 means there is little to no physical exertion, and an RPE of 10 means that an individual is exerting themselves to the max. For high intensity interval training, most protocols consider an RPE of 7-9 to be high intensity and an RPE of 10 to be a sprint.

Is one method better than the other?

This depends on what you have available to you, and how experienced you are. If you are just starting out, it is very important to check in on how you are feeling during a workout and use that as your guidepost. If you are really feeling fatigued and breathing heavily during a workout, it doesn’t really matter what percentage your heart rate is calculated at. Once you have gained some more experience about how higher intensity exercise feels, then you can use a heart rate monitor to really dial in how hard you are working. At the beginning though, we recommend you frequently check in with how you are feeling and use that as your guide.

Are there benefits unique to Interval Training?

As you may have heard us say before, it is important to remember that there is no bad form of exercise unless you are doing something that could potentially cause you injury or harm. When it comes to interval training, there is a ton of overlap in terms of the benefits you get when you compare it to Zone 2 Exercise and Resistance Training. With all of these forms of exercise you are getting:

• Improvements in your fitness and decreasing your risk of heart disease
• Improving your blood pressure
• Contributing to weight loss and maintaining a healthy weight
• Improving your exercise performance

That said, there are some specific benefits to interval training that we would like to highlight. These are outlined below:

1. Improved VO2 Max:

VO2 Max is defined as the maximum oxygen consumption that can be achieved during exercise. This means the amount of oxygen we can extract from our environment (AKA breathing), absorb into our blood stream, and then be delivered to our muscles.

Interval training is thought to be the most efficient way to increase VO2 Max, so much so that you will sometimes hear interval training referred to as VO2 Max training.

Important note: Moderate intensity continuous exercise can also provide significant benefits to VO2 max, but the exercise must be done for a much longer period of time and research shows that the results are less pronounced.

In many observational studies, VO2 max is the best indicator of overall fitness and having a higher VO2 max is correlated with living longer and healthier lives. Pretty convincing!

2. Improved Brain Health

When we do high intensity interval training, our bodies increase production of a very important protein called Brain Derived Neurotrophic Factor, often referred to as BDNF. BDNF is essential for the survival of neurons in our brain, plays an important role in learning and memory, and is important for improving our mood. Without BDNF, we would all be in rough shape to say the least.

In fact, BDNF is a very hot topic in the scientific world given its potential to potentially protect against Alzheimer’s disease.

Coupled with the fact that HIIT workouts can increase blood flow to the brain, interval training is emerging as a potent tool in our toolkit to improve and maintain the health of our brains.

3. Decreases Cancer Risk

It is well known that regular exercise can help decrease the risk of cancer over the course of a lifetime. But are there additional benefits to be gained from interval training? Possibly! Researchers in Israel published a study in 2022 that showed a 72% reduction in the risk of metastatic cancer in individuals who participated in regular intense aerobic exercise over a 20-year period. That’s a big deal!

4. Takes Less Time