High Intensity Interval Training: Is it Right for You?
Everywhere you look you see ads, and articles for HIIT, Tabata training, boot camps, and all sorts of daylong events that challenge participants fitness limits. What is High Intensity Interval Training (HIIT)? What makes this type of exercise so popular? Who is it targeted to? What are the benefits, what are the concerns? High intensity interval training is an exercise regimen that alternates between short bouts of high intensity exercise with rest periods for a specific number of calisthenics, plyometrics, resistance exercises, cycling, etc. It has become one of the most popular fitness trends over the past few years, but its origin was almost 20 years ago.
In 1996, Izuam Tabata, a coach with the Japanese Olympic speed skating team, tried a new training regimen where the athletes rode a stationary bike at an intense pace for 20 seconds followed by 10 seconds of rest, repeated 8 times. Over 6 weeks the athletes VO2max improved 14%, considered a significant amount. VO2max is the indicator of how much oxygen a person uses in a minute per kg of body weight. More simply put, it is a measure of your cardiovascular health. The results were published and created a huge amount of interest in the fitness community. Since then trainers and gyms across the country (and internationally), most notably CrossFit, are using this style of training with their clients. Exercise DVD programs such as P90X and Insanity are hugely popular and available for home use.
To answer the questions of personal trainers and the general public, the American Council on Exercise (ACE) authored 2 recent studies led by John Porcani, head of Clinical Exercise Physiology at the University of Wisconsin. Sixteen participants ages 16-47 performed 4 rounds of 4 calisthenics (such as jump rope, burpees, lunges, box jumps, etc) alternating 20 seconds of work, 10 seconds of rest with 1 minute rest between rounds, a total of 20 minutes. The researchers analyzed heart rate, VO2max, and calories burned. Their results: higher intensity for short periods = improved fitness and weight loss. The second study put 2 Crossfit work outs to the test. One big difference with Crossfit and other HIIT workouts is participants perform a prescribed number of reps in the shortest amount of time thereby adding the element of competition between participants. Again the results showed greater improvements in aerobic capacity and calorie consumption than traditional aerobic training (moderate intensity over longer period of time). Bottom line; participants see results in a shorter period of time which is very appealing to many who have time constraints. The researchers cautioned that Crossfit is not for everyone. Participants should be screened carefully and likely would already have a good level of fitness. Also it is essential that there be 48-72 hours of rest between sessions to avoid injury.
A more general study published in the American Journal of Health Promotion looked at data from the National Health and Nutrition Examination Survey, a national program that has been collecting health and nutrition data in the U.S. since 1999. The study divided the over 4000 18-64 year olds into 4 groups comparing those who did high intensity, short bouts of walking with moderate intensity long bouts of walking. The results showed that for every minute spent walking at a pace of 3 miles/hour (considered high intensity) for less than 10 minutes, BMI decreased, as did the risk of becoming obese. This is important information for those who are overweight and not getting the federally recommended 150 minutes of moderate exercise per week for any number of reasons.
All the researchers agree that Crossfit and other HIIT style programs are not for everyone. Someone who is just beginning to exercise and/or has any health or orthopedic concerns should discuss their plans with their doctor. In addition it is important that your structural alignment be checked (and corrected if necessary) by a qualified physical therapist specializing in manual therapy skills. There have been many documented cases of overdoing it especially in group classes where there is very competitive atmosphere. Especially concerning are cases of Rhabdomyolosis, a very serious condition which occurs when muscles suffer severe tissue damage and myoglobin leaks into the bloodstream, resulting in damage or shutdown of the kidneys. As was stated earlier, rest and recovery are essential components of HIIT.
If your doctor gives you the ok to try HIIT, but you’re not quite ready to dive into a class, the American Council of Exercise recommends choosing an aerobic exercise such as stationary bicycling . Do a 5 minute warmup, then 1 minute of more intense cycling where you perceive your effort to be in the 7-9/10 range (perceived as “hard”). Recover with slow cycling for 2 minutes and repeat 3-4 times. You can gradually increase to 8-10 1 minute intense bouts. This type of regimen should only be done 1-2 times per week and used only periodically for up to 6 weeks rather than year round.
Another option, If you enjoy walking, is to pick up your pace for 1-2 minutes at a time, then return to your regular pace for 5 minutes. Gradually increase the number of times you walk more briskly in a given walking session, paying particular attention to any increase in muscle soreness that lasts more than 2 days indicating you may be overdoing it.
You could also select 4-6 common calisthenics that are high, low or no impact, depending on your fitness level. Warm up first, do 20 seconds of one exercise as intensely as you are able (perceived exertion in the 7-9/10 range) , followed by 10 seconds of rest (walking around). Repeat with all exercises. Rest for 1-2 minutes. Gradually add another round up to 4 rounds. Again incorporate this only 1-2 times per week for 6 weeks at time.
If you don’t want to go it alone, hire a certified personal trainer to guide you. The advantages are the trainer will ensure you are getting personal attention to meet your stated goals, and you are doing the exercises correctly. At some point you may decide to try a group HIIT class that many trainers offer. The overall goal is to get the results you are looking for without overdoing it and risking injury.
Author: Charlene Pilon, PTA,BPE, PT-ACE