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ACSM Information On

HIGH-INTENSITY INTERVAL TRAININGThe popularity of high intensity interval training is on the rise. High intensity interval training sessions are commonly called HIITworkouts. This type of training involves repeated bouts of high intensity effort followed by varied recovery times.

A Complete Physical Activity Program A well-rounded physical activity program includesaerobic exercise and strength training exercise, butnot necessarily in the same session. This blend helpsmaintain or improve cardiorespiratory and musculartness and overall health and function. Regular physicalactivity will provide more health benets than sporadic,high intensity workouts, so choose exercises you arelikely to enjoy and that you can incorporate into yourschedule.

ACSMs physical activity recommendations for healthyadults, updated in 2011, recommend at least 30 minutesof moderate-intensity physical activity (working hardenough to break a sweat, but still able to carry on aconversation) ve days per week, or 20 minutes of more vigorous activity three days per week. Combinationsof moderate- and vigorous-intensity activity can beperformed to meet this recommendation.

Examples of typical aerobic exercises are:

Walking Running Stair climbing Cycling Rowing Cross-country skiing Swimming

In addition, strength training should be performed aminimum of two days each week, with 8-12 repetitionsof 8-10 different exercises that target all major musclegroups. This type of training can be accomplished usingbody weight, resistance bands, free weights, medicineballs or weight machines.

The intense work periods may range from 5seconds to 8 minutes long, and are performedat 80% to 95% of a persons estimated maximalheart rate, the maximum number of times your heart will beat in a minute withoutoverexerting yourself. The recovery periods maylast equally as long as the work periods and areusually performed at 40% to 50% of a personsestimated maximal heart rate. The workoutcontinues with the alternating work and reliefperiods totaling 20 to 60 minutes.

What are the benets of HIIT?HIIT training has been shown to improve: aerobic and anaerobic tness blood pressure cardiovascular health insulin sensitivity (which helps the exercising

muscles more readily use glucose for fuel to

make energy) cholesterol pro les abdominal fat and body weight while

maintaining muscle mass.

Why is HIIT Training so Popular?HIIT training can easily be modied for peopleof all tness levels and special conditions,such as overweight and diabetes. HIIT workouts can be performed on all exercisemodes, including cycling, walking, swimming,aqua training, elliptical cross-training, and inmany group exercise classes. HIIT workoutsprovide similar tness benets as continuous

endurance workouts, but in shorter periods otime. This is because HIIT workouts tend toburn more calories than traditional workoutsespecially after the workout. The post-exerciperiod is called EPOC, which stands forexcess postexercise oxygen consumption. This generally about a 2-hour period after anexercise bout where the body is restoring itseto pre-exercise levels, and thus using moreenergy. Because of the vigorous contractilenature of HIIT workouts, the EPOC generallytends to be modestly greater, adding about 6to 15% more calories to the overall workoutenergy expenditure.

How do You Develop a HIIT ExercisProgram? When developing a HIIT program, considerthe duration, intensity, and frequency of the

work intervals and the length of the recoveryintervals. Intensity during the high intensity work interval should range 80% of yourestimated maximal heart rate. As a goodsubjective indicator, the work interval shouldfeel like you are exercising hard to veryhard. Using the talk test as your guide, it would be like carrying on a conversation, widifculty. The intensity of the recovery intervshould be 40-50% of your estimate maximalheart rate. This would be a physical activitythat felt very comfortable, in order to help yorecover and prepare for your next work interv

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Staying Active Pays Off! Those who are physically active tend to live longer,healthier lives. Research shows that moderate physicaactivity such as 30 minutes a day of brisk walking signicantly contributes to longevity. Even a person with risk factors like high blood pressure, diabetesor even a smoking habit can gain real benets fromincorporating regular physical activity into their dailylife.

As many dieters have found, exercise can help youstay on a diet and lose weight. Whats more regularexercise can help lower blood pressure, control bloodsugar, improve cholesterol levels and build stronger,denser bones.

The First StepBefore you begin an exercise program, take a tness teor substantially increase your level of activity, make sto answer the following questions. This physical activreadiness questionnaire (PAR-Q) will help determine i youre ready to begin an exercise routine or program.

Has your doctor ever said that you have a heartcondition or that you should participate in physicalactivity only as recommended by a doctor?

Do you feel pain in your chest during physical activi In the past month, have you had chest pain when you were not doing physical activity?

Do you lose your balance from dizziness? Do you evlose consciousness?

Do you have a bone or joint problem that could bemade worse by a change in your physical activity?

Is your doctor currently prescribing drugs for yourblood pressure or a heart condition?

Do you know of any reason you should not participain physical activity?

If you answered yes to one or more questions, if you aover 40 years of age and have recently been inactive,or if you are concerned about your health, consult aphysician before taking a tness test or substantiallyincreasing your physical activity. If you answered no teach question, then its likely that you can safely begiexercising.

Prior to ExercisePrior to beginning any exercise program, includingthe activities depicted in this brochure, individualsshould seek medical evaluation and c learance to engain activity. Not all exercise programs are suitable foreveryone, and some programs may result in injury. Activities should be carried out at a pace that iscomfortable for the user. Users should discontinueparticipation in any exercise activity that causes pain odiscomfort. In such event, medical consultation should

be immediately obtained.

ACSM grants permission to reproduce this brochure if it is reproduced in its entirety without alteration. The text may be reproduced in another publication if it is used in its enwithout alteration and the following statement is added: Reprinted with permission of the American College of Sports Medicine. Copyright 2014 American College of Spor

This brochure is a product of ACSMs Consumer Information Committee. Visit ACSM online at www.acsm.org.

The relationship of the work and recoveryinterval is important. Many studies use aspecic ratio of exercise to recovery to improvethe different energy systems of the body. Forexample, a ratio of 1:1 might be a 3-minutehard work (or high intensity) bout followed bya 3-minute recovery (or low intensity) bout.These 1:1 interval workouts often range about3, 4, or 5 minutes followed by an equal time

in recovery. Another popular HIIT trainingprotocol is called the spring interval trainingmethod. With this type of program theexerciser does about 30 seconds of sprint ornear full-out effort, which is followed by 4 to4.5 minutes of recovery. This combination ofexercise can be repeated 3 to 5 times. Thesehigher intensity work efforts are typicallyshorter bouts (30 seconds with sprint intervaltraining).

What are the Safety Concerns with HIITTraining?Persons who have been living rather sedentary

lifestyles or periods of physical inactivitymay have an increased coronary disease riskto high intensity exercise. Family history,cigarette smoking, hypertension, diabetes (orpre-diabetes), abnormal cholesterol levelsand obesity will increase this risk. Medicalclearance from a physician may be anappropriate safety measure for anyone withthese conditions before staring HIIT or anyexercise training. Prior to beginning HIITtraining a person is encouraged to establish afoundational level of tness. This foundationis sometimes referred to as a base tnesslevel. A base tness level is consistent aerobic

training (3 to 5 times a week for 20 to 60min per session at a somewhat hard intensity)for several weeks that produces muscularadaptations, which improve oxygen transport tothe muscles. Establishing appropriate exerciseform and muscle strength are important beforeengaging in regular HIIT to reduce the risk ofmusculoskeletal injury.

Regardless of age, gender and tness level,one of the keys to safe participation of HIITtraining is for all people to modify the intensityof the work interval to a preferred challenginglevel. Safety in participation should always

be primary priority, and people should focusmore on nding their own optimal trainingintensities as opposed to keeping up with otherpersons.

How Many Times a Week Can You doa HIIT Workout?HIIT workouts are more exhaustive thensteady state endurance workouts. Therefore, alonger recovery period is often needed. Perhapsstart with one HIIT training workout a week, with your other workouts being steady state workouts. As you feel ready for more challenge,add a second HIIT workout a week, makingsure you spread the HIIT workouts throughoutthe week.

Final HIIT MessageInterval training has been an integral partof athletic training programs for many yearsbecause a variety of sport and recreationalactivities require short bursts of movement athigh intensities. Interval training is becomingan increasingly recognized and well-likedmethod of training. The incorporation ofinterval training into a general conditioningprogram will optimize the development ofcardiorespiratory tness as well as numerousother health benets. Give HIIT a try.

Brochure content provided by Len Kravitz, Ph.D.