HIIT or High intensity interval training is a type of interval training exercise. It includes several rounds, that alternate between several minutes of high intensity movements to significantly increase the heart rate to at least 80% of one’s maximum heart rate, followed by short periods of lower intensity movements. Interval training was first introduced in the 1950s as a higher intensity form called Sprint interval training, which reached 100% maximum heart rate and was used to improve the performance of elite Olympic athletes.
One of the top reasons for not exercising is “I don’t have time!” as many traditional workouts push a commitment of about an hour. High intensity interval training, or HIIT, challenges this barrier by incorporating an effective workout in half that time.
Body weight can be used as the main form of resistance so that additional equipment is not needed. HIIT workouts also generally do not require a large amount of space, making the format ideal for a home workout. HIIT workouts can be integrated into various exercise formats, such as running (outdoors or on a treadmill), dancing, rowing machines, stationary bicycles, or stair climbers. The interval durations can be timed by using one to five-minute.
HIIT can help to decrease body fat, increase strength and endurance, and improve health outcomes, but it is not necessarily better than other exercise formats. Its main appeal is that it can achieve similar fitness and health benefits in a shorter duration, and that it includes periods of rest.
Other terms that are used interchangeably with HIIT are Tabata and circuit training. Tabata is a form of HIIT that was created by Professor Izumi Tabata in 1996 involving Olympic speedskaters. His exercise intervals were extremely high intensity, followed by very brief rest periods. Fitness centers and gyms that offer Tabata classes are typically 20-30 minutes and encourage participants to reach their highest intensity ability, but they can self-regulate their workouts. Circuit training involves 8-12 exercise stations that target different muscle groups. Participants rotate through each station, completing one exercise that lasts several minutes. The difference with circuit training is that the intensity is variable, whereas HIIT encourages maximum effort by reaching 80-90% maximum heart rate.
Example (A beginner HIIT workout)
This workout can be performed at home using just an exercise mat and a timer or clock.The speed of each exercise can be faster or slower, depending on one’s fitness level, but encourages the participant to work to their maximum ability. A 5-minute warm-up of walking or marching in place should be performed before the workout, and a 5-10-minute cool-down of slower movements allowing the heart rate to gradually decrease, along with stretches, should be included to end the workout
- 30 seconds of side lunges, alternating right to left
- 15 seconds of slow marches in place
- 30 seconds of squats (variation for higher intensity: jump squats)
- 15 seconds of slow marches in place
- 30 seconds of push-ups on the floor (modification: at a 45-degree angle on a sturdy chair, or against the wall)
- 15 seconds of slow marches in place
- 30 seconds of jumping jacks (modification: alternate right and left tapping toes to the sides while bringing arms overhead as you would a jumping jack)
- 15 seconds of slow marches in place
- 30 seconds of triceps dips using a sturdy chair or bed
- 15 seconds of slow marches in place
- 30 seconds of alternating high knees (variation for higher intensity: jogging high knees)
- 15 seconds of slow marches in place
- 30 seconds of sit-ups (modification: sit-ups on a stability ball, or abdominal crunches on the floor
REST FOR 60 SECONDS AND REPEAT THE SESSION 2 MORE TIMES
HIIT workouts should be tailored to the individual’s fitness level and medical conditions. Research has generally found HIIT to be a safe and enjoyable exercise for a range of ages and medical conditions. A meta-review of HIIT compared with control groups found HIIT to be safe (no acute injury reports or serious cardiovascular events) in controlled supervised settings, with mean compliance rates in completing the program reaching >80%.
HIIT (High intensity interval training) and Health
HIIT is a well-researched exercise format, showing benefits for a range of medical conditions across a broad age range, from adolescents to older adults. [6] In research studies, HIIT is typically compared with moderate intensity continuous training (MICT), which incorporates lower intensity movements at a constant pace without interval breaks. Whereas HIIT causes individuals to reach 80-85% of their maximum heart rate, MICT reaches about 55-70% of their maximum heart rate.
When energy expenditure remains the same for HIIT versus MICT workouts, some studies show a greater benefit with HIIT because it achieves greater aerobic capacity (the body’s ability to use more oxygen). Although initially applied to athletes to improve their performance, HIIT is now included as a potential exercise option for individuals with chronic diseases. It can help to improve their physical functioning, exercise tolerance, and quality of life.
Although the higher intensities reached with HIIT formats may appear too difficult for people with chronic diseases, research has shown that the intermittent rest intervals and overall shorter duration of the exercise make HIIT a potentially feasible and safe option for even more serious conditions like lung disease, heart disease, and chronic kidney disease under close supervision. Modifications may be implemented, such as using specific exercises or incorporating longer warm-up and cool-down periods for people with heart disease or on blood pressure medications. Some research in these populations found HIIT to be rated more enjoyable and with longer-term compliance than MICT. However, larger and additional studies need to be performed with these at-risk groups before routinely prescribing HIIT. HIIT has also been found to improve depression more than MICT in people with major depression or bipolar disorders, without reported adverse events.HIIT involves short bursts of intense exercise alternated with low intensity recovery periods. Interestingly, it is perhaps the most time-efficient way to exercise.
HIIT not only provides the benefits of longer-duration exercise in a much shorter amount of time but also may provide some unique health benefits.
HIIT benefits
- HIIT can burn a lot of calories in a short amount of time
- Your metabolic rate is higher for hours after HIIT exercise
- HIIT can help you lose fat
- You might gain muscle using HIIT
- HIIT can improve oxygen consumption
- HIIT can reduce heart rate and blood pressure
- HIIT can reduce blood sugar
- HIIT improves aerobic and anaerobic performance
Absolute Contraindications
- Obstructive left main artery disease
- Unstable angina
- Uncontrolled cardiac arrhythmia
- Acute endocarditis, myocarditis, or pericarditis
- Moderate to severe aortic stenosis
- Acute pulmonary embolism, or deep vein thrombosis
- Higher degree heart block
- Hypertrophic obstructive cardiomyopathy
- Recent stroke or transient ischemic attack
- Uncontrolled Diabetes
- Severe autonomic or peripheral neuropathy
- Acute systemic illness or fever
The bottom line
It is a very efficient way to exercise and may help you burn more calories than you would with other forms of exercise.Some of the calories burned as a result of high intensity intervals come from a higher metabolism, which lasts for hours after exercise.
HIIT is an effective exercise option to increase endurance and strength in those who have limited time to exercise. Because of the higher intensity format, it is advised to consult with a physician if you have any medical conditions before starting a HIIT program. All participants new to HIIT should choose a program that is facilitated by an exercise professional.
Overall, HIIT produces many of the same health benefits as other forms of exercise in a shorter amount of time.These benefits include decreases in body fat, heart rate, and blood pressure. HIIT may also help lower blood sugar and improve insulin sensitivity.
So, if you’re short on time and want to get active, consider trying high intensity interval training.
