Interval Training - What is It? Rules and Effects of Interval Exercises
Interval training is a popular workout method that can be used by both beginners and experienced athletes. It’s a type of high-intensity exercise that may support weight loss while improving endurance and overall fitness. HIIT training - what is it? How do interval exercises work? HIIT results after one month - what can be the effects of regular interval workouts?
Table of contents
What are intervals?
Interval training is a workout method that involves alternating between intense physical efforts and lower-intensity activities.
Unlike traditional sports, which usually focus on performing exercises at a steady pace, interval training forces the body to constantly adapt to changing conditions. This makes intervals an extremely effective form of physical activity.
Intervals – the high-intensity segments – can improve heart performance, which in turn may lead to what’s called an “oxygen debt.” This stimulates the metabolism to keep working harder even after the workout is over. As a result, interval exercises can activate muscles and support fat burning.
Types of intervals
Interval training isn’t uniform – there are several types of sessions that can be adapted to the athlete’s individual needs and training goals.
Athletes often practice classic interval training, which involves activities performed at about 80% of maximum heart rate. A very popular choice among physically active people is HIIT (High Intensity Interval Training), considered a workout done at 85–95% of maximum heart rate. Another type is SIT (Sprint Interval Training), which can reach up to 100% of maximum heart rate. A popular and widely used form of intervals is tabata.
Exercise intensity and maximum heart rate
In interval training, intensity plays a key role and can be monitored through the maximum heart rate (HRmax) – the highest number of beats per minute an athlete can reach without risking their health. HRmax is individual and depends on factors such as age, sex, genetics, physical fitness, and training experience.
There are several ways to estimate maximum heart rate. One of the most popular methods is a formula from Liverpool John Moores University:
- for men: HRmax = 202 − (0.55 × age),
- for women: HRmax = 216 − (1.09 × age).
Other methods include a running test, where the athlete gradually increases effort until two minutes of maximum exertion at the end, and a simplified formula: HRmax = 220 − age.
Determining HRmax is essential for properly planning interval training, as it allows defining the intensity zone in which the athlete should work. However, different methods may produce different results, so it’s always important to listen to your body and adjust intensity to personal capabilities, remembering that safety should come first.
Interval training plan - how to prepare interval exercises?
Planning is key to effective interval training. A well-structured HIIT plan should include gradual progression, safety, and adaptation to the athlete’s current fitness level.
Both beginners and advanced athletes starting with intervals should begin with milder forms of interval workouts, gradually increasing volume and intensity. This reduces the risk of injury and helps the body adapt to new challenges.
Example interval workout
Interval training is intense yet highly varied, so it can be adapted to different preferred activities.
Runners can do track intervals, such as mile repeats – running a mile at high intensity, followed by a brisk walk – to adapt the body to a slightly faster pace than during races.
Those who prefer to train at home can try a 15-minute HIIT session made up of short but very intense exercises alternated with lower-intensity moves. A home interval workout might include jump squats, push-ups, crunches, or jumping jacks.
Another example is cycling intervals: riding at high intensity for 30 seconds, followed by slower-paced cycling.
Whatever the type of interval workout, always start with a warm-up and finish with stretching to reduce the risk of injury.
HIIT - exercise and rest duration
When planning an interval workout, you should also consider exercise duration and rest periods. Typically, intervals are recommended for 10–30 minutes due to their high intensity, which is challenging for the nervous and cardiovascular systems. Longer sessions are not advised. The exact length depends on the athlete’s level and goals.
The work-to-rest ratio should match the overall intensity. HIIT athletes may need longer breaks between high-intensity efforts than those doing classic intervals at lower heart rates.
A common recommendation is that if an intense effort lasts 30 seconds, the rest period should be 60–90 seconds at lower intensity.
Interval training frequency
How often should intervals be done to get results? Usually, it’s recommended to perform interval workouts 2–4 times per week, depending on fitness level and training goals. Beginners should start with 1–2 sessions weekly, gradually increasing to 3–4.
Because intervals are demanding, the training plan should include enough recovery time. At least one rest day between workouts is recommended to protect the muscles and avoid overtraining.
Who are intervals for?
HIIT can be a great option for those aiming to lose weight. It’s also useful for athletes wanting to boost performance or break training plateaus.
Interval exercises can also be beneficial for those who want to shorten their workout time without sacrificing results.
Interval training for beginners
Beginners should pay attention to a few important aspects before starting. HIIT is very intense, so it’s important to start with easier forms and gradually build up.
It’s best to begin with simple sessions, such as running for one minute at high intensity followed by two minutes of slow jogging, repeated 3–4 times. Cycling is also a good choice for beginners, as bike intervals put less strain on the joints and carry a lower risk of injury.
During training, remember that intervals aren’t a race – safety and consistency are the priorities.
HIIT - effects and benefits
Intervals are short but intense exercises that can deliver quick results. They can make it easier to achieve training goals.
HIIT can help burn fat – the intense effort can create an “oxygen debt” that increases energy expenditure during and after training. This means you can burn calories not only during exercise but also afterward.
Studies suggest that regular interval training can improve cardiovascular performance by increasing VO₂ max and enhancing aerobic and anaerobic capacity. This boosts endurance and performance in other sports and physical activities.
HIIT can also support muscle growth and strength, especially when combined with strength training. It can improve mood, reduce stress, and enhance agility and speed. Because HIIT requires discipline and focus, it can also strengthen motivation and help build healthy habits.
Results from interval training can be visible after just a few weeks. One month of consistent workouts can help slim the figure, improve oxygen capacity, and boost overall fitness and well-being.
Interval training and weight loss
Regular interval training combined with a balanced diet and a proper calorie deficit can be a valuable tool for weight reduction.
The “oxygen debt” effect can speed up metabolism, leading to continued calorie burn after exercise.
HIIT may be more effective for fat loss – especially belly fat – than traditional cardio. Short intervals under 30 minutes can burn the same or more calories than a one-hour steady jog.
Interval training vs. cardio
Interval training and cardio are different workout styles with different benefits.
Cardio is a steady-intensity endurance workout lasting over 30 minutes. Interval training alternates between high and low intensity, usually lasting less than 30 minutes.
Intervals are more intense, which can help burn calories quickly and improve overall fitness. Cardio, however, strengthens the heart, supports circulation, and helps regulate blood pressure and glycogen levels during exercise.
Cardio is often recommended for people with heart problems who should avoid high-intensity exercise. Choosing between them depends on goals, preferences, and physical abilities – both can produce excellent results.
Interval training - contraindications
Interval training is effective but not suitable for everyone. HIIT should be avoided by people with heart disease, circulatory disorders, uncontrolled hypertension, or diabetes.
Because high-intensity exercise can stress the joints, especially the knees, people recovering from injuries or with joint problems should consult a doctor or physiotherapist before starting intense interval workouts.
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