High-intensity interval training (HIIT), defined as alternating periods of high-intensity exercise (85% or higher of maximum heart rate) followed by rest intervals, continues to be one of the most popular exercise trends worldwide. It is important to note that rest intervals do not necessarily mean resting or inactivity, but can include periods of less-intense exercise (e.g., low-intensity resistance sets) and active recovery (e.g., dynamic stretching).
The key to safe and effective HIIT programming is to acknowledge that each person has different baseline fitness. What is defined as high intensity for one person may be either too intense or not challenging enough for someone else. The key is to determine how high intensity is defined for each individual, and then modify your training methods and exercise intensity for each client or participant.
To achieve the goal of HIIT modification, start with a review of the three key programming variables associated with HIIT:
Intensity (how hard) Volume (how much or how long) Rest periods
A couple things to keep in mind:
Intensity and volume are inversely related. The higher the intensity of the exercise, the shorter the all-out work or high-intensity interval will be. The higher the intensity of the exercise, the longer the rest period will be.
To modify HIIT, use training methods that keep clients active and heart rate up, and focus on specific muscle groups at one time instead of focusing solely on the intensity or effort of exercise.
Supersets involve doing two exercises back to back. They are a great way to keep people moving while focusing on specific muscles. Typically, the muscle groups used complement one another—either working together (e.g., synergist supersets like a back exercise followed by a biceps exercise) or agonist-antagonist supersets (e.g., a triceps exercise followed by a biceps exercise).
Another way to do supersets is to alternate cardiovascular exercise with resistance exercises. For example, you could have your client walk on an incline on a treadmill for one minute and then perform a set of 15 lunges for each leg. The superset can be repeated multiple times to increase volume, or the time on the treadmill can be changed along with the number of repetitions performed each set. The intensity can be controlled by manipulating the incline on the treadmill and the amount of weight used (or not used) during lunges.
Circuits are a series of exercises performed in succession, and