Benefits of High Intensity Interval Training (HIIT)


Fitness Tips

It seems like with every new year, comes new fitness trends and work out programs. Over the past few years, High Intensity Interval Training OR HIIT has been at the forefront of fitness magazines and news headlines and is becoming an increasingly popular topic at universities and research facilities across the world. So, what exactly is HIIT and what is so unique about this approach to training?

While there is no universal definition, HIIT is characterized by working at high intensities (usually, > 80% of your max heart rate) for moderate amounts of time with short intervals of rest in between. Due to the “all out” nature of these workouts, HIIT workouts typically last around 30 minutes. What is so unique about these intense, focused workouts, is the increased cardiovascular and muscular conditioning benefits that can be gained in the same amount of time verses traditional workouts.

 Research has shown tremendous benefits by replacing 1 hour of steady state cardio per week with two 30-minute sessions of HIIT in healthy adults who exercise consistently.

In a study completed at Penn State University, Dr. Jinger Gottschall researched the effects of HIIT training on already active adults.  Over a 6-week period, she found that participants who replaced 1 hour of steady state cardio with two sessions of 30 minute HIIT achieved the following gains:

  • Improvement of their VO2 max (maximum oxygen consumption rate) by 6.4%
  • On average, a 14.5% decrease in triglycerides
  • On average, a 2.1% decrease in body fat
  • On average, a 15.7% increase in leg strength

For the endurance athletes competing at higher level competitions, research has shown similar results in improving overall endurance, most notably in long distance runners.

So, what does all of this really mean? For the already active adult who may find themselves in a fitness “rut”, replacing 1 hour of steady state cardio with two 30-minute sessions of HIIT training may offer diversity and efficiency to your workout regimen, especially for those with limited time.

 IT’S NOT FOR EVERYONE: While the benefits of incorporating HIIT training into your daily workout routine are enticing, there are a few things to consider before starting. Due to the “all out” and often times high impact nature of HIIT, these types of workouts are generally not recommended for those who are just starting an exercise regimen. New types of HIIT programs are beginning to appear, incorporating cycling as a lower impact option to those seeking this alternative. While modifications can be made to reduce impact, it is best to consult with your physician or physical therapist to see if this type of exercise regimen is appropriate for you and your fitness goals.

While HIIT may not be right for you initially, a physical therapist can help prepare you for the increased physical demands of a HIIT program so that you can train intensely with reduced risk of injury. Hartz Physical Therapy also offers a Medically Adapted Gym program where you could initiate HIIT training, in a supervised setting to optimize your success. Happy training!


Gottschall, J. , Bopp, C. and Hastings, B. (2014) The Addition of High Intensity Interval Training Reduces Cardiovascular Disease Risk Factors and Enhances Strength in Active, Healthy Adults. Open Journal of Preventive Medicine, 4, 275-282. doi: 10.4236/ojpm.2014.45034.

Metabolic Adaptations to Short-term High-Intensity Interval … : Exercise and Sport Sciences Reviews. (n.d.). Retrieved from https://journals.lww.com/acsm-essr/Fulltext/2008/04000/Metabolic_Adaptations_to_Short_term_High_Intensity.3.aspx