// Caloric expenditure - Does water exercise make the grade?

by Kimberley Huff

The American College of Sports Medicine (ACSM) recommends a caloric expenditure of 150 to 400 calories per day just to maintain physical function.

It recommends that previously sedentary individuals may benefit initially from a minimum expenditure of 1000 calories per week. They further recommend that to achieve weight loss, overweight adults expend 2000 calories per week.

What does this mean for two different women? If previously sedentary Betty has a simple goal of improving her health and fitness levels she needs to participate in a program that elicits a minimum calorie expenditure of 1000 calories per week. On the other hand, Sally, who wants to lose weight, would require a caloric expenditure of 2000 per week from her exercise program.

Can water exercise help Betty and Sally?

The Aquatic Exercise Association in the US reported that in normal conditions, where the water temperature is 28 to 30 degrees Celsius, performing a combination of exercises that involve the upper and lower body at armpit depth water would result in a caloric expenditure of approximately 400 to 500 calories per hour. So if Betty participated in a 60 minute aqua exercise class, two or three times a week, she would satisfy the minimal requirements established by ACSM. If she was not able to tolerate 60 minutes of continuous exercise, she may benefit initially from 30 minutes of water exercise, four to five days per week. Sally, on the other hand, would benefit from attending a 60 minute aqua exercise class a minimum of four times a week.

This may seem like a lot of exercise for the previously sedentary Betty, but research has also shown that both she and Sally would have to exercise longer to achieve the same caloric expenditure on land. A study reported on by J Lindle1,2 that compared upper and lower body exercises performed on land to the same upper and lower body exercises performed in chest-depth water resulted in a greater caloric expenditure when performing the exercises in the water. The water exercises resulted in a caloric expenditure that was 1 to 2 calories per minute more than the exercises performed on land. This suggests that both Sally and Betty could possibly expend 60 to 120 more calories per hour if they exercise in the water, than if they participate in a land-based exercise class.

How can that happen?

An understanding of the factors that contribute to caloric expenditure could make this information difficult to believe. Firstly, the number of calories used during exercise is directly related to the weight of the body – the heavier the body, the more work required to move it. For example, if Sally and Betty were walking together (on land) at the same pace and Betty weighed 64 kilos and Sally weighed 80 kilos, it is likely that Sally would be expending more calories due to her body weight.

The buoyancy of the water decreases body weight so the actual weight of the body does not increase caloric expenditure with water exercise. Many researchers have concluded that the increase in energy cost of water exercise is due to the resistive

Individual characteristics that can affect caloric expenditure include age, fitness level and gender. Younger people typically have a higher metabolic rate than older people, so if Sally was older than Betty and all factors were equal (water depth, resistance, etc.), Betty may experience a greater caloric expenditure than Sally. However, if Sally has significant experience with exercise, specifically water exercise, and Betty was previously sedentary, Sally may experience a greater caloric expenditure.

A study published that compared the effects of experienced deep water runners with inexperienced deepwater runners showed that the experienced runners were able to obtain a higher workload and thus a greater caloric expenditure than the inexperienced runners.

Do we make the grade?

Research studies have concluded that participation in an appropriately designed water exercise program can result in a caloric expenditure that satisfies the ACSMs recommendations for maintaining physical fitness and for weight loss. This means that Betty could possibly achieve her initial goal of 1000 calories per week. Sally could possibly reach her weight loss goal of 2000 calories per week. However, their success will be dependent upon body position in the water, motivation, experience, initial fitness level, the temperature of the water and their willingness to work hard.

Individual characteristics that can affect caloric expenditure include age, fitness level and gender. Younger people typically have a higher metabolic rate than older people, so if Sally was older than Betty and all factors were equal (water depth, resistance, etc.), Betty may experience a greater caloric expenditure than Sally. However, if Sally has significant experience with exercise, specifically water exercise, and Betty was previously sedentary, Sally may experience a greater caloric expenditure.

A study published that compared the effects of experienced deep water runners with inexperienced deepwater runners showed that the experienced runners were able to obtain a higher workload and thus a greater caloric expenditure than the inexperienced runners.

Do we make the grade?

Research studies have concluded that participation in an appropriately designed water exercise program can result in a caloric expenditure that satisfies the ACSMs recommendations for maintaining physical fitness and for weight loss. This means that Betty could possibly achieve her initial goal of 1000 calories per week. Sally could possibly reach her weight loss goal of 2000 calories per week. However, their success will be dependent upon body position in the water, motivation, experience, initial fitness level, the temperature of the water and their willingness to work hard.

This article has been reprinted with permission from AKWA (www.aeawave.com)

References

1. Lindle, J. How Many Calories? Nokomis, FL: Aquatic Exercise Association, 2002. 2. Lindle, J. Aquatic Fitness Professional Manual. Nokomis, FL: Aquatic Exercise Association, 2006.

 

Kimberly Huff, MS CSCS
Kimberly is certifi ed by NSCA, ACSM, ACE, and AEA. She has over 20 years experience in fi tness and therapy settings. She has authored several articles for the Aquatic Exercise Association (AEA)’s AKWA journal and currently serves on the AEA’s Research Committee. Kim has presented at national and international fitness conferences and presents certification review courses for ACSM and AEA.


GROUP EXERCISE, MIND BODY & AQUA NETWORK • SPRING/SUMMER 2007 • PP3-4