In the quest for an “ideal” fitness activity, an ever-increasing number of exercise participants are discovering water exercise as an alternative to traditional land-based programs.

By Werner W.K. Hoeger.

The benefits of many “land-based” fitness activities have been well documented in both medical and fitness literature. Many of these popular activities such as jogging, aerobics and rope skipping, however, are contraindicated for people with selected muscular-skeletal problems. The reality of activity injuries is not only a threat for these people, but also for athletes, fitness enthusiasts, rehab patients, overweight individuals and many others. In the quest for an “ideal” fitness activity, an ever-increasing number of exercise participants are discovering water exercise as an alternative to traditional land-based programs. Water-based exercise is the fastest growing fitness choice of both trained and untrained individuals in the United States.(1) From an initial 200,000 participants in 1983, more than 2.2 million people participated in aquatic exercise in 1988.(2)

The recent increase in popularity can be attributed to several factors: a) buoyancy reduces weight-bearing stress on joints and, therefore, reduces the risk of injury; b) it is a more feasible type of exercise for overweight individuals and those with arthritic conditions who may not be able to participate in weight-bearing activities; and c) heat dissipation in water is beneficial to obese participants who seem to undergo a higher heat strain than average-weight individuals. Aquatic exercise experts anticipate that this trend will continue to increase at a very rapid rate over the next decade.

One of the most popular forms of aquatic exercise is water aerobics. This activity provides fitness, fun and safety for people of all ages, with virtually no impact to the muscular or skeletal systems. During water exercise, vigorous limb movements against the water’s resistance provide the training stimuli for cardio-respiratory development.3 Recent studies conducted at Boise State University in Idaho have looked at water aerobics as an exercise modality for fitness development.

An initial study(4) compared the training benefits between water aerobics and low-impact aerobics. Twenty subjects participated in a water aerobics class, 15 subjects enrolled in a low-impact aerobics class and 14 subjects were assigned to a control group. Training sessions for the exercise groups were of similar length, duration and intensity.

The exercise groups participated in an eight-week training program, three times per week, for about 45 minutes per exercise session. The aerobic phase of each session lasted 20 minutes at a training intensity between 70 and 85 percent of land-based heart rate reserve. This aerobic phase consisted of a series of rhythmic movements designed to elevate the heart rate to the prescribed exercise intensity. The aerobic stage for both water and land were followed by an additional 20 minutes of stretching and toning exercises.

For the water aerobics group, stretching and toning exercises were conducted in water against the edge of the pool. Additionally, all subjects (experimental and control) were instructed not to participate in other fitness activities that might influence the results of the study.

The study provided evidence that both water and low-impact aerobics produce training benefits following an eight-week exercise program. The exercise groups showed improvements in cardio-respiratory fitness, resting heart rate, percent body fat, flexibility and strength. The improvements were similar for both exercise groups with the exception of strength. Muscular strength gains were greater for the water aerobics group. This finding was attributed to the added resistance to limb movement caused by the water during exercise.

A subsequent study5 compared maximal physiological responses between treadmill running and water aerobics. The results indicated that maximal heart rate and oxygen uptake (a measure of cardio-respiratory fitness) obtained through a maximal treadmill running test could not be duplicated during a maximal water aerobics protocol. Maximal heart rate for water aerobics was 10 bpm lower, and maximal oxygen uptake was only 84 percent of the maximal value achieved on the treadmill. These data are consistent with results of swimming research. Maximal heart rates achieved during swimming are about 10 to 13 bpm lower than land-based maximal heart rates.

As a result of these findings, news media across the country concluded that water aerobics is not an effective exercise modality for cardio-respiratory development. The findings of the latter study, however, only compared maximal exercise responses and not actual training intensities that are sustained during an aerobic workout. Although maximal water aerobics responses are similar to maximal swimming responses, no one has claimed that swimming is not an effective aerobic exercise.

Due to the misinterpretation of these results, additional research(6) was conducted to investigate the actual exercise heart rate and oxygen uptake during a self-paced water aerobics workout. The American College of Sports Medicine (ACSM) guidelines for the development and maintenance of cardio-respiratory fitness in healthy adults recommends training between 60 and 90 percent of maximal heart rate or 50 to 85 percent of maximal oxygen uptake.(7)

Twelve subjects (six males and six females) who regularly participate in an aerobic exercise program were used in the third study. An initial maximal graded exercise test was given to all subjects to determine their maximal heart rate and maximal oxygen uptake while running on land. Seven days later, each subject was asked to perform a series of water aerobic exercises that were simultaneously demonstrated by an instructor in the water. All subjects were fitted with a heart rate monitor prior to the exercise session. The exercise heart rate, however, was not visible to the participant, and none of the subjects was given feedback regarding heart rate or oxygen uptake during data collection.

Prior to data collection, all participants were instructed to exercise at their preferred aerobic pace. Each subject warmed up for five minutes to gradually increase the intensity to their preferred aerobic rate. The water exercises during warm-up phase were the same exercises subsequently used during data collection. Following the five-minute warm-up, the subjects were connected to a gas analyzer and physiological data were collected during the next five minutes. The average heart rates were collected during the next five minutes. The average heart rate and oxygen uptake for the last four minutes of the exercise session were used to determine the self-paced training intensity.

Data analyses indicated that all subjects met the minimum ACSM guidelines for cardio-respiratory development and maintenance. The average exercise heart rate in the study was 142.8 bpm, or the equivalent of 75.8 percent of their maximal heart rate. Oxygen uptake was 31.8 ml kg per minute or 61.3 percent of their maximal treadmill values. ACSM recommends a minimum training intensity of 60 percent of maximal heart rate, or 50 percent of maximal oxygen uptake.

The results of this last study showed that water aerobics is an effective exercise modality for cardiorespiratory fitness. Although maximal physiological land values cannot be duplicated in water, this does not mean that water aerobics is a less effective exercise modality. Aerobic training intensities (or exercise prescriptions) are always submaximal intensities and, as the latter study shows, water aerobics exceeded the minimum ACSM recommendations. Furthermore, every one of the 12 subjects met the minimum ACSM intensity criteria for both heart rate and oxygen uptake.

Another point of interest is that many exercise specialists recommend that exercise intensities in water should be lowered to accommodate for the lower maximal heart rate achieved during water-based activities (both water aerobics and swimming). One can argue, however, that apparently healthy people are able to achieve higher work capacities during land-based activities; therefore, the same exercise intensity can be given for water aerobics. In the self-paced water aerobics study, all subjects met the minimum exercise intensity according to land-based prescriptions. If a lower intensity is used, training benefits may be decreased.


Sanders, M.E., & C. Crutcher. Taking the plunge. Fitness Management, 6 (3): 75-77, 1990.
LeCompte, J.D., & S. Antony. Water exercise: Wave of the ’90s. Fitness Management, 5 (4): 25-27, 1989.
Spitzer, T., & W.W.K. Hoeger. Physical fitness: The water aerobics way. Englewood, CO: Morton Publishing Co., 1990.
Hoeger, W.W.K., T.S. Gibson, J. Moore, & D.R. Hopkins. A comparison of selected training responses to low impact aerobics and water aerobics. National Aquatics Journal, 9 (1), 13-16, 1993.
Hoeger, W.W.K., D.R. Hopkins, D.J. Barber & T.S. Gibson. A comparison of maximal exercise responses between treadmill running and water aerobics. Medicine and Science in Sports and Exercise, 24 (5), S96, 1992.
Hoeger, W.W.K., T.S. Gibson & J. Varner. Oxygen uptake and heart rate responses to self-paced water aerobics exercise. Unpublished data. Boise State University, 1993.
American College of Sports Medicine. Position stand on the recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness in healthy adults. Medicine and Science in Sports and Exercise, 22 (2): 265-274, 1990.

Walking is a good aerobic workout.

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