What is interval training and why is it so popular? Is interval training best for fat loss? And what are the top 3 interval workouts to use?
In this week’s addition to the ‘Athletic training for average Joes’ series, we are going to look at interval training. Interval training has gained popularity due to the premise of giving maximum results in the shortest time possible. The claim is that performing interval workouts, lasting between four and thirty minutes, can give you maximum results in terms of burning fat, building strength, and improving endurance. But how true is that?
During this article, we will look at the history of interval training, some of the benefits it can bring, and how you should perform it. We’ll also give you the top 3 interval workouts to use.
Fitness fad or the future of fitness?
The health and fitness industry has seen many trends and fads introduced over the years. We covered some of these in our functional fitness blog previously. One trend that has made a significant impact is interval training. There are hundreds of variations of interval workouts available, with many companies claiming their version is the best.
Today’s modern lifestyle comes with two common themes: having busy schedules and wanting results yesterday. The beauty of interval training is that, on paper, it ticks both of those boxes. Interval training boasts the ability to melt body fat, grow muscle and build strength, power and endurance, all within a 20-30-minute workout. It’s almost impossible not to have your interest piqued by interval training.
What is interval training?
In short, it is a workout in which you mix bursts of work at maximal effort followed by short rest periods for repetitive bouts. You work at a higher rate than you would in a ‘normal’ workout which allows you to get the equivalent amount of work done in a shorter time frame. The intensity of work determines the amount of rest. The goal is to stress your cardiovascular system to improve your VO2Max.
VO2Max is the amount of oxygen you can take in and use as a fuel for activity. If you have a high VO2Max, you will be able to perform aerobic exercise for more extended periods. As an example, if you improve your VO2Max, you could run at a faster pace before you become fatigued. The science shows that the best way to enhance VO2Max is not only to perform regular aerobic exercise but also by completing frequent anaerobic work. When you work anaerobically, you perform short bursts of high output without using oxygen. Sticking to the running example, the more sprint work you do, the more your casual run output will also increase.
You may not think you perform any interval training; however, a standard weights workout is a type of interval training. Let us say you are performing a chest workout. You do four exercises, and for each, you are doing three sets of 12 repetitions with one-minute rest per set. You are performing a set amount of work, with short rest periods. By the basic definition, this is interval training. There are numerous ways you can set up an interval workout, including a four-minute variant! We will discuss variations later in the article.
The history of interval training
Although interval training has only recently become a part of the mainstream fitness industry, it has been around since the early 1900s. It is the sport of running that we can thank for the introduction of interval training. Swedish running coach Lauri Pikhala created an interval training protocol for runner Paavo Nurmi around 1910. The programme focused on using a mixture of effort levels over different distances. Finnish gold medallist of the era, Hannes Kolehmainen, also used this method.
This first version of interval training was more ‘fluid’ in its application. Rather than prescribed intensities and durations, you would mix different effort levels with different distances, depending on how you felt in that session. This method was known as speed play or ‘Fartlek’ in Swedish. This method is one of the better variations for beginners due to its flexibility – you can work as hard as you can for as long as you can, then ease off and rest as long as needed.
German coach Woldemar Gerschler later introduced the more structured version of intervals we are accustomed to today. This protocol has you performing a high intensity run for a set distance, followed by a long rest, or walk to allow for greater recovery. The longer recovery periods meant that you could keep performance levels up as the session progressed. The structured method is essentially sprint training that is used by most athletes today. You sprint a set distance, usually between 50 and 100 meters, then recover for up to five minutes before repeating. The work is at maximum effort, which is why the distance is short.
The four-minute workout
One of the latest studies into interval training and its effect on fitness is known as the Tabata experiment. Conducted by Japanese scientist Izumi Tabata, the study looked at the metabolic profile of interval training. They wanted to understand the effect of high-intensity interval on the aerobic and anaerobic energy systems used by the body. The experiment took nine participants and subjected them to a 4-minute workout, performed over four sessions, as well as one steady-state cardio workout per week. The Tabata experiment used a cycle ergometer, which is like a stationary exercise bike with a specialised resistance mechanism. The workout itself started with a 10-minute warm-up followed by 4 minutes in which participants repeated for eight rounds a circuit of 20 seconds at maximum output followed by 10 seconds rest. They then finished with a 10-minute cooldown.
Participants had several statistics measured before, during and after the experiment, which lasted eight weeks in total. Tabata found that the participants subjected to his protocol had significant increases in their aerobic and anaerobic fitness, as well as reduced body fat, increased leg mass and power output. It was these results that lead to fitness professionals replicating the Tabata protocol into a workout. You might believe that Tabata training should be the primary method everybody should use – performed only four times per week, in less than 25 minutes total you can get maximal results. However, it’s not as simple as that, and there are several factors to consider.
The participants used
During this experiment, all the participants used were athletes on sports teams. The participants already had a decent level of fitness before conducting this test. Not only did they have a good base of fitness, they would have a better understanding of intensity levels. When you are regularly exposed to exercise, you quickly learn what different intensity levels feel like, and thus know when you are working at the levels requested.
The equipment used
As mentioned, the experiment was conducted on cycle ergometers. These bikes allow for fine-tuned resistance to be added or removed at an instant. The ergometers also record data for the scientist to analyse. Ergometers are more commonly found in sporting laboratories and not found in gyms. More importantly, the monitoring and adjusting of resistance are digital, making it more accurate.
This type of output is not easy to replicate on other cardio equipment, which means replicating the results is also tricky. There have been further attempts to replicate the protocol with different exercises. As found in this study, they were unable to replicate the same results.
The output required
Performing the Tabata protocol requires you to work at maximal effort for multiple bursts of activity. Not only is this a hard task, the bouts are performed in quick succession, making it even harder to complete. You may not have ever been pushed to work at maximum output before, which takes time and a strong fitness base to master. As someone who has replicated the Tabata protocol on the correct equipment, I was unable to complete all eight rounds working at the same intensity level. I performed this test when I was at the peak of my athletic development with an already ‘elite’ level of VO2Max.
It is almost unethical to ask an untrained individual to complete strict Tabatas due to the risk involved, as well as the ability to complete the workout.
Based on the above, it is safe to say that you are unlikely to replicate the Tabata protocol results. That does not mean that you cannot attempt to incorporate a similar structure. You may wish to include two sessions per week where, after a warm-up, you perform 4 minutes of 20 seconds work, 10 seconds rest for eight rounds with a challenging exercise. It will still have SOME effect on improving your fitness. However, it will not give the same results as following the strict Tabata protocol. If you are new to interval training or exercise, you should build a solid fitness base first before employing such a high-intensity exercise method.
Superior fat burning – myth or fact?
One of the main attractive points about Interval training is the fact it can promote ‘all day fat burning’. Compared to steady-state cardio, interval training is supposed to be better in general for fat loss. Now, although there is some truth to this statement, the actual results are not as impressive as they seem. Here I will break down some of the facts for you:
24-hour fat burning
First, we need to look at the claim of the additional fat-burning period. A single bout of interval training will indeed leave you burning more calories all day long. Performing an interval workout will increase your post-exercise energy expenditure for about 14 hours. The measured elevation of metabolism is equivalent to an extra 37% of the calories burned during the workout. This works out to be approximately 200 calories over the 14 hours. To give you some perspective to the benefit this would provide, a Mars bar contains 228 calories.
So, in reality, you will burn more calories throughout the day; however, it is not as high as you might have been led to believe. You will also need to follow a calorie deficit to ensure you reach your fat loss goals.
Increase your metabolism
It has been suggested that Interval training increases your resting metabolic rate (RMR). RMR is the number of calories you burn to keep your body functioning when at rest. The idea is that after you perform interval training, your body will increase its RMR to help recover from the intense exercise. As this study points out, although interval training did not have a direct effect on the RMR, it did, however, have an impact on the Total Daily Energy Expenditure (TDEE). What does this mean to you? Well, adding interval training will help you increase your daily energy expenditure. For you to benefit from this for fat loss, you will still need to be in a daily calorie deficit. I bet you’re beginning to see the pattern forming, aren’t you?
Targeted fat loss
One belief is that interval training targets body fat stores to provide energy to complete and recover from the workouts. The theory is that intense exercise increases adrenaline production, which increases lipolysis. Lipolysis is the process of breaking down stored body fat to be utilised as fuel. During this study, they found that you would need to commit to at least 12 weeks of structured interval training for your body to benefit from the lipolysis effect. There was also another factor, and I bet you already know what I am about to say.
The take-home on interval training and fat loss
Interval training is a logical way to increase energy expenditure as a way to help fat loss. You will be required to be in a CALORIE DEFICIT for fat loss to occur, regardless of what method of training you use. You can create a calorie deficit in three ways: either consuming less food, increasing your daily activity, or a mixture of both. It can be easier for you to achieve fat loss by eating a little less and moving a little more. Interval training has the added benefit of being time-efficient, so you do not have to spend hours in the gym to see the results.
Why perform interval training?
You may be thinking “hold on; you’ve just spent a decent amount of time telling me that interval training isn’t as magical as believed, so why should I do it?”. There are several reasons why you should consider using interval training in your exercise programme.
Time-efficient calorie expenditure
As the above point explains, interval training is still a valid, time-efficient way to burn more calories. For most people who exercise recreationally, you fit your exercise in and around your daily routine and commitments. You may currently be missing training sessions in the belief that you do not have time spare to get a decent workout completed. Interval training can allow you to spend less time exercising while still benefiting from the results of the exercise.
Improve cardiovascular fitness
Not only is it time-efficient, as already discussed, it can help you increase cardiovascular fitness. Intervals allow both your aerobic and anaerobic capacities to improve. You should combine a mixture of interval training and steady-state cardio throughout the week to get the best benefits possible. You can start with shorter, less intense sessions and slowly work on increasing the intensity, as well as the number of rounds you complete.
Rapid results in untrained individuals
There is a misconception that you require a high level of fitness to conduct interval training: this is not entirely true. You will need a high fitness level to complete high-intensity interval training. However, as explained at the start of this article, Fartlek training allows you to dictate the amount of work performed. This journal highlights one study that found ‘sedentary individuals’ were able to significantly increase their VO2Max in 10 weeks, in some cases by as much as 44%. The take-home here is that you can start interval training, as long as you work within your capability levels.
Improve insulin sensitivity
Your body uses glucose for energy and to top up energy stores. Insulin sensitivity is a measure of how well your body cells take up glucose for usage and storage. There is a close association between low insulin sensitivity – insulin resistance – and high body fat levels. Insulin resistance is also a precursor to type 2 diabetes.
A study performed in 2009 using a test group of young, healthy males to establish if exercise influenced insulin sensitivity. The study showed that following a 2-week H.I.I.T programme, insulin sensitivity was improved by 23%. It also showed that Improved insulin sensitivity will help to reverse the negative health implications of high blood sugar and pre-diabetes.
Improve cholesterol levels
There have been multiple studies that have looked at the relationship between cholesterol and exercise. Interval training has a direct effect on improving your ‘good’ cholesterol levels. You would need to adhere to a minimum of 8 weeks of interval training, alongside a healthy diet and calorie deficit to see a marked effect on total cholesterol levels.
Reduce the risk of coronary heart disease
Vigorous exercise is more beneficial at reducing the risk of coronary heart disease compared to steady-state exercise. Many clinical and epidemiological studies conducted have highlighted the benefits. As this paper shows, HIIT was shown to be superior to continuous moderate exercise in reducing blood pressure and improving left ventricular and myocardial function, alongside the previously mentioned improvements in VO2Max and lipid profiles.
Top 3 interval sessions to use
Fartlek Running intervals
If you have not performed intervals before or you would like an easy introductory method, try Fartlek running. Use a good warm-up, such as the one highlighted here. Set yourself a time limit of thirty minutes. During this time frame, you are going to mix it up! Run at a fast pace some of the time. Then, when you need to, slow down to a jog or walk pace. Remain at this pace until you feel able to work at a higher pace again. The next time you speed it up, you might go at three-quarter pace but keep it up for longer. Then after a rest, you might go faster again. Keep this going for thirty minutes. You can either increase the total time with each session or keep a record of your run and walk times and aim to improve the ratios as each session progresses.
Fartlek intervals are also an option for days when you feel good for a workout, but not a high-intensity session. All you require is space to run and a timer. You can do the same on a x-trainer or a stationary bike playing with speed and resistance levels. Using the above equipment will remove the impact stress caused by running.
All over body interval session
This interval session is one that you can do at home with zero equipment. Try to select a mixture of compound exercises which are not technically complex to perform. For example, I suggest the following:
- Burpees (any variation you can perform)
- Push up variation
- Mountain climbers
- Squat jumps
For the workout, you will perform each exercise for 5 minutes in total. You can do one of two things. Either do all five minutes of the first exercise in one go before moving to exercise two, and so on. Or in rounds, perform one minute of each exercise, and do five rounds of 4 exercises each. Break each minute down into work and rest. For an easy interval, you perform 20 seconds work, 40 seconds rest per minute. For an intermediate workout, you’d perform 30 seconds work 30 seconds rest per minute. If you want a more intense workout, perform 40 seconds work and 20 seconds rest per minute.
You can use any number of exercises for this method. One circuit variation is called a ‘bear complex’ in which you perform all exercises in the circuit with one barbell. A bear complex looks like this:
- Stiff leg deadlift
- Bent over row
- Hang power cleans
- Push Press
- Front squat
You perform each exercise back to back in one of the work: rest protocols mentioned above for four to ten total rounds.
Tabata protocol – 20:10 x 8
For Tabatas, you will want to perform a good warm-up for at least 10 minutes to get your heart rate raised and muscle fibres primed. After your warm-up, you will complete eight rounds of 20 seconds work followed by 10 seconds rest. As soon as you finish the final round, you will perform up to 10 minutes of a steady-state cooldown.
You should complete this method on equipment that allows you to reach maximum effort quickly. Here are some of the better options for exercise equipment or exercises to perform:
- A concept2 rower.
- A ski-erg.
- An assault bike (also known as an Airdyne bike).
- A Watt bike.
- Battle ropes.
- Burpees – bodyweight or wearing a weighted vest.
- Squat jumps – bodyweight or wearing a weighted vest.
- Thrusters performed with either a barbell, dumbbell, or kettlebells.
You could perform the intervals as sprints on a treadmill; however, you will want to set the treadmill on a high incline as well as speed. You will also need to be able to hop on and off the treadmill without slowing it down. This method carries the most risk; therefore, only perform this if you have experience in the technique.
Interval training is a valid method to allow you to improve health and fitness in a time-efficient way and create a calorie deficit to aid fat loss. Beware that some of the claims made by fitness professionals regarding the benefits of interval training have been slightly ‘stretched’. Nonetheless, intervals are still a beneficial exercise technique.
Everyone can do interval training; however, your fitness level will determine which method is best suited for you. Performing a mixture of interval sessions and steady-state cardio is the best approach for improving fitness as well as aiding fat loss.
The next article in the ‘Athletic training for average Joes’ series will be the last instalment. I will give you an example of how to combine all the methods learned in this series to create an athletic training programme.