HIIT training has become increasingly popular due to research evidence showing positive results in weight management and fitness gains in a reduced time. HIIT is the acronym to describe High-Intensity Interval Training. It can be cardio, resistance-based, or a combination of the two. HIIT consists of short intense work intervals at almost breathless or breathless intensity, followed by a recovery period.
When it comes to cardiovascular HIIT training the physiological benefits include: increase in VO2 max (the ability of the body to take in and utilize oxygen enabling the body to work harder for longer periods on time), improved insulin receptivity (important for managing blood sugar levels which is important in preventing and managing Diabetes type 2), and improved endothelial function (the health of the lining of the arteries and veins improve resulting in enhanced cardiovascular functioning). When engaging in HIIT workouts, the improvement in these parameters is higher than if the participant engaged in continuous aerobic exercise providing that the intensity high enough.
Due to the increased intensity of HIIT, more calories are burned in a shorter amount of time with the potential benefit of decreased fat tissue and enhanced lean tissue as the body is overloaded muscular and anaerobically. Body composition change is a product of intensity and duration. By incorporating some HIIT workouts in a weekly program, participants are seeing positive results.
All this good news comes with a note of caution. Adding more HIIT training to your weekly workout routine does not necessarily mean that the positive results continue to go up. High intensity requires the participant to train at their anaerobic threshold or higher (the level at which a participant cannot breathe fast enough to meet muscle demands). This is not easy, can be unpleasant, and is not the ideal type of workout for a newcomer to exercise. The potential for injury is higher and the challenge to the cardiovascular system can be risky for some.
Several factors need to be considered when engaging in HIIT workouts. How fit are you? What is your experience with interval-based workouts? Do you have underlying health issues? Are you able and willing to exercise at or above your anaerobic threshold? It is important to slowly build up to HIIT training workouts to avoid injury, learn proper exercise techniques, and build a fitness base in order the handle high-intensity work.
To truly achieve the full benefits of a HITT workout, you have to work hard enough.
During and after HIIT training workouts the recovery period is as important as the work to get the most gains. During high-intensity effort, the body tissues have been broken down and they need to rebuild after the intense overload achieved during the workout. Many experts recommend about 25% to 30% of your weekly training be HIIT intensity.
The rest of the workout program can involve a long duration and moderate or lower intensity aerobic activity. Adding resistance training to your weekly fitness regimen will increase the function of the lean tissue in the body with the result that you are stronger and have more metabolically efficient muscle tissue. As well, flexibility training is important to help prevent injury, to enhance range of motion while executing exercise, and to complement the recovery aspect of the participant's program.
In conclusion, aerobic HITT training can be very valuable in enhancing the physiological improvements achieved through cardiovascular training. Manipulating work and recovery intervals allow for infinite variety in your workouts. Remember, it is about the quality of the HITT workout, not the quantity. Work hard; recover well.
Marcus K.Kilpatrick Ph.D., Mary E.Jung, Ph.D., and Jonathan P. Little, Ph.D., High Intensity Interval Training; A Review of Physiological and Psychological Responses, ACSM Health and Fitness Journal, Volume 18 -Number 5, pages 11-16