By Mary Edwards, Precor Master Coach and Fitness Director at the Cooper Fitness Centre in Dallas, TX

HIIT is a popular mode of training in our industry today, but exactly what is it and how do you choose the right HIIT protocol?

What is HIIT?

• HIIT stands for High Intensity Interval Training
• Alternating work and recovery periods using your own body weight (such as running or strength movements), functional training equipment (kettlebells, ropes, etc.) or cardiovascular equipment
• Work periods may range from five seconds to eight minutes in duration and are performed at 80-95% of estimated maximal heart rate (MHR)
• Recovery periods are relative to your work period and should allow the exerciser to return to 40-50% MHR before beginning the next work period

(Kravitz)

Benefits of HIIT

The benefits of HIIT are research proven! In our time crunched society, HIIT has been very popular for providing physiological results in less time. Research has shown that HIIT improves cardiovascular capacity (aerobic and anaerobic fitness), blood pressure, and insulin sensitivity, as well as decreases abdominal fat stores and cholesterol (Gunnarson and Bangsbo; Kravitz). HIIT also has been used effectively among clinical populations to improve VO2 and blood glucose control (Dalleck). Research has confirmed HIIT is an effective and versatile form of training for all fitness levels (assuming the exerciser is medically cleared to participate in an exercise programme).

The “Right” HIIT Protocol

The options for HIIT workouts are endless, and thus, it can be overwhelming for the general public or Fitness Professional to determine which protocol is the best to apply for a specific health goal or client, respectively. The truth is there is no incorrect protocol, but research suggests that some protocols may prove most effective for certain populations. There were five key studies that showed HIIT has a positive impact on VO2max, blood glucose control, and fat metabolism of clinical populations (Dalleck). The work intervals ranged from 60 seconds to four minutes among the studies. Understanding the challenging nature of interval training, we will highlight the following protocol:

New to HIIT or have an existing clinical condition (and medically cleared to exercise):  

The ranges above allow the exerciser to progress over time. It also is understood that the exerciser complement HIIT with moderate intensity exercise sessions on a weekly basis to achieve five days or more of cardiorespiratory conditioning (Garber et al).

Athlete or well-trained exerciser seeking to improve performance:

Research has shown this protocol improved VO2 max, running performance (1500 m and 5km), systolic blood pressure, and total cholesterol. Studies suggest that exercising continuously after 10 seconds at near maximal exertion has a major impact on the cardiovascular system (Gunnarsson and Bangsbo).

HIIT can be accomplished by anyone medically cleared to exercise. It can be a valuable tool in improving cardiovascular fitness and health variables in an efficient and effective manner. Please note the above protocols are representative of specific research and training populations. It may be necessary to modify the above intensity or duration of work intervals relative to a specific fitness level or exercise goal.

References:

1. Dalleck, L. High Intensity Interval Training for Clinical Populations. ACE Fitness Certified News, June 2012.
2. Garber, CE et al. Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise. Med. Sci. Sports Exerc 43: 1334-1359, 2011.
3. Gunnarsson TP and Bangsbo J. The 10-20-30 training concept improves performance and health profile in moderately trained runners. Journal of Applied Physiology. 113: 16-24, 2012.
4. Kravitz L. High Intensity Interval Training. American Colleges of Sports Medicine, 2014.