Energy Expenditure in Different Modes of Exercise

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Energy Expenditure in Different Modes of Exercise
One of the primary goals of an exercise program is to develop and maintaincardiorespiratory fitness. Many people engage in aerobic activities to improve their healthstatus, reduce disease risk, modify body composition and improve all around physicalfitness. It is important to select a mode of exercise that uses the large muscles of the bodyin a continuous, rhythmical fashion, and that is relatively easy to maintain at a consistentintensity. It is interesting to note that not all modes of exercise are comparable in terms ofenergy (caloric) expenditure. However, several factors, in addition to energy expenditure,should be considered when selecting an exercise mode.

Classification of Aerobic Exercise Modalities
The American College of Sports Medicine (ACSM) classifies aerobic exercise modes by thevarying skill demands of the activity. Group I activities provide a consistent intensity andenergy expenditure that are not dependent on the participant’s skill level. These wouldinclude activities such as walking, cycling, jogging, and simulated stair climbing. With GroupII activities, the rate of energy expenditure will vary greatly depending on the person’sperformance ability. With higher skill levels, a person can work harder and longer, andconsequently burn more calories. Activities in this category would include aerobic dancing,bench stepping, hiking, swimming and water aerobics. The Group III activities, such asbasketball, racquet sports, and volleyball are highly variable in terms of energy expendituredue to the performance demands of the activity. For long-term cardiovascular health, it isimportant to select a variety of activities that sufficiently stimulate the heart, lungs, andmuscles.

Exercise Mode Considerations
In addition to energy expenditure, some factors to consider when selecting a mode ofexercise include personal interest, equipment and facility availability, physical needs, injuryrisk and fitness goals. Therefore, selecting the appropriate mode(s) of exercise is essentialfor continued consistent energy expenditure. It is meaningful to note that additional healthand fitness benefits will be attained as the amount and intensity of exercise increase.

Intensity of Exercise: Optimizing Energy Expenditure
A major way to optimize energy expenditure is to vary the intensity of the exercise. It isimportant to choose a mode of exercise that can be adjusted or graded to overload thecardiorespiratory system. For instance, treadmill walking can be made much morechallenging by increasing the treadmill grade. Cycling intensity can be made moredemanding by increasing the pedaling resistance. Adding a step riser to elevate thestepping height can boost the step aerobics workout intensity. In addition, choosing a modethat allows for high intensity intervals interspersed with low-to-moderate intensity intervalsmay also increase energy expenditure.

Upper and Lower Body Modalities
Some exercise modes involve both the upper and lower body muscles, such as swimming,rowing, and simulated skiing. Although these types of exercise engage more muscles, theydo not necessary engage as much muscle mass as running, and so will expend slightlyfewer calories at a similar level of intensity. However, swimming involves much lesspressure on the bones and joints, which allows swimmers to exercise for a longer period oftime, thus possibly expending as much energy as higher intensity workouts. Also, someupper and lower body exercise modes, such as simulated skiing, require a fairly proficientskill development phase before fully realizing the energy expenditure benefits.

Non-Weight-Bearing versus Weight-Bearing Modalities
Cycling and recumbent cycling are two very popular non-weight-bearing exercise modes,whereas walking and jogging are popular exercises in the weight-bearing category. At thesame level of intensity, most persons will expend more calories performing a weight-bearingactivity. An additional benefit of weight-bearing exercise is maintaining bone mass andpreventing osteoporosis. However, with cycling and recumbent cycling there is much lesstrauma to the muscles and joints, heart rate is generally lower, and thus longer exercisebouts are possible.

Walking versus Running
Both walking and running require very little skill and are convenient modes of exercise. Briskwalking, which is one of the most popular aerobic activities in the U.S., has been shown toproduce positive health benefits. From an energy expenditure standpoint, running will burnmore calories than walking due to the increased intensity of the activity. However, increasedzeal to boost energy expenditure with running compounds the risk of injury to the feet,ankles, knees and back. Some persons choose to carry hand-held weights in hope ofenhancing energy expenditure when walking. Although the use of hand-held weightsincreases the perceived intensity of the exercise, research reveals that this additionalequipment does not satisfactorily increase energy expenditure.

Choosing the Exercise Mode:
The Final DecisionAlthough research results suggest that weight-bearing aerobic exercise, at a self-selectedintensity, will elicit the highest energy expenditure, several other considerations have beendiscussed for selecting an exercise mode. Because of the great diversity of aerobic exerciseequipment presently available, more and more exercise enthusiasts now prefer to crosstrainon a variety of exercise modes, which combines high exercise enjoyment with reducedmusculoskeletal risk.

Written for the American College of Sports Medicine by Len Kravitz, Ph.D. and Chantal A.Vella, M.S.
 
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