|A Low-Impact Exercise Alternative
Colleen McGlone, B.S., Len Kravitz, Ph.D.,
and Jeffrey M. Janot, Ph.D.
Rebounding is a form of aerobic exercise that emerged nearly 50 years ago (1). A modern-day version of rebounding may now be seen in fitness clubs throughout the United States. This form of group-led exercise appears to provide an adequate stimulus for improving and maintaining cardiovascular fitness, and it may also be a good choice of exercise for clients needing a low-impact option. Rebounding involves performing basic physical movements, similar to traditional aerobic classes, on a mini-trampoline device referred to as a rebounder.
Although rebounding is not new to the fitness world, it has changed since its debut. It now incorporates more contemporary arm and leg choreography to music, as well as a different rebounding performance style. Early rebounding technique can be characterized as running and bouncing movements that recoil upward from the rebounder. The present-day rebounding method involves less upward motion and more of a downward push of the legs onto the rebounder. This pushing movement limits the amount of upward propulsion, while increasing the amount of physical work being performed by the legs. The upper-body limbs perform various bilateral and unilateral movements, such as flexion and extension of the arm and forearm in the sagittal, horizontal, and frontal planes.
The physiological benefits of this contemporary rebounding program are not known. In addition, a comparison of rebounding with other modes of exercise has not been investigated. Therefore, we assessed the cardiovascular responses of rebounding and treadmill exercise performed at the same level of perceived exertion.
A group of 10 trained men and women who were participating in 30 minutes or more of aerobic activity, 3 times a week, volunteered (see Table 1). (Data sponsored in part by a grant from QVC. Inc.)
Method of Exercise Testing
Two different exercise sessions were used. Participants learned the proper techniques of each movement to be performed on the rebounder. All instruction was provided and demonstrated by a certified fitness professional, who taught subjects the routine and led them during the rebounding session. This routine incorporated several different movements including basic double-leg rebounding with hands on the hips, 90° bent-arm chest flies with double-leg rebounding, military presses with double-leg rebounding, jumping jacks, double twists, and alternating y 1||| stride moves. This familiarization period continued until each exerciser was comfortable performing the movements. The participant was then given a 10-minute rest period before beginning the exercise sessions. During this period the Borg's Ratings of Perceived Exertion (RPE) scale was reviewed (3).
Table 1. Physical Characteristics of Participants*
Age (yr) 28.2 ± 11.3 24.0 ±3.9
Height (cm) 175.5 ± 4.2 169.0 ±5.4
Weight (kg) 73.9 ± 10.3 60.1 ± 8.2
Body Composition (BF) 13.6 ± 4.6 18.1 ±2.9
HRmax (BPM) 190.6 ± 11.7 194.8 ±3.8
VO 2max (ml(Kg'nm)-1) 52.4 ± 9.8 45.3 ±2.8
* Values are means ± standard deviation
The first exercise bout involved rebounding for a period of 10 minutes following the standardized instruction format led by the certified instructor. This consisted of performing each of the rebounding moves described above for 16 repetitions, and continually rotating through the sequence for the length of the session. The music accompaniment was set at 126 beats per minute (BPM). This session was followed by a 10-minute seated rest period before beginning the second 10-minute exercise bout. To best equate the starting physiological parameters of exercise for both bouts, the participants remained resting until oxygen consumption percentage for participants was 18 for the female participants values of the first trial were attained. The second bout consisted of a self-paced treadmill-jogging period that participants were classified as being in the Superior" category matched each subject's rebounding RPE. The treadmill was set at a 3% grade and the subjects self-selected the speed in order to effectively match the same level or intensity perceived on the rebounder. The treadmill exercise was also accompanied by music set at 126 BPM.
Oxygen consumption (VO2), Ventilation (VE), and respiratory exchange ratio (RER) were measured continuously and averaged across every 15 seconds throughout the sessions. Heart rate (HR) was taken every 30 seconds and then averaged. RPE on the rebounder was measured every 3 minutes and then averaged for the session.
What We Found
The participants in this study had body fat percentages below established norms (2). The average body fat percentage for participants was 18% for the female participants and 13.6% for the male participants. VO2max values for all participants were classified as being in the "Superior" category based on age and gender (2) (see Table 1).
Cardiovascular and Caloric Expenditure
The data showed comparable cardiovascular results between and treadmill exercise at the same level of perceived exertion (see TabIe 2). There was no significant difference in VO2 and HR between the rebounder and the treadmill. The heart rate response or subjects averaged 81% or HRmax for rebounding and 82% or HRmax for treadmill exercise. The oxygen consumption response of subjects averaged 63% of VO2max reserve for rebounding and 66% of V02maxR for treadmill. There was no significant difference in energy expenditure between the rebounder and the treadmill. Rebounding yielded an average of 9.45 ± 1.75 Kcals/min as compared to 10.07 ± 3.0 Kcals/min on the treadmill.
The results indicate that V02, HR, and energy expenditure were all very comparable between the two exercise modalities. Rebounding exercise meets the American College of Sports Medicine (ACSM) Guidelines (4) in several categories, notably that it produced HR intensities between 55% and 90% of maximal HR, which are necessary for improvement of cardiorespiratory fitness. Rebounding exercise attained this recommendation (81 of HRmax), indicating that improvement and maintenance of cardiorespiratory fitness can be achieved with rebounding exercise. ACSM recommends aVO^ intensity of 40 to 85 of maximum oxygen uptake reserve (VO2maxR) for cardiorespiratory improvement, which rebounding exercise also produced (63% ofVO2maxR).
The kilocalorie expenditure averaged 9.45 Kcals/min, which was similar to the treadmill energy expenditure of 10 Kcals/min. ACSM (4) recommends a target range of 150 to 400 Kcals of energy expenditure per day in physical activity for overall health benefits. Therefore, if rebounding were performed for a minimum of 16 minutes it would meet the lower threshold of this recommendation.
A desirable weight-loss program usually includes a caloric restriction component in addition to an exercise component. ACSM (4) recommends participation in an exercise program that promotes a daily caloric expenditure of more than 300 Kcals. This suggests that rebounding for 32 minutes or more will meet this recommendation for most individuals.
The similarity in caloric expenditure between rebounding and treadmill exercise can be explained by the use of RPE as an exercise intensity control variable between the two modes of exercise. These data suggest that participants were able to reproduce a similar exercise intensity on the treadmill compared with rebounding exercise by using only a subjective rating of their physical effort. This is worth noting because of the belief that RPE may be mode-specific, meaning that it may be difficult for the exercising individual to march a given exercise intensity between different exercise modes. In light of this finding, rebounding exercise appears to elicit a similar caloric expenditure at a matched RPE as treadmill exercise, without exposing individuals to impact forces experienced on the treadmill.
It has been estimated that 80% of aerobic-related injuries are caused by overuse and microtrauma associated with the repetitive impact forces inherent in most aerobic techniques (5). Rebounding may help to reduce injuries commonly related to other forms of exercise such as jogging. One benefit of rebounding is that the rebounder absorbs and decreases the amount of impact sustained by the joints. This decreased force may be beneficial in preventing overuse injuries such as shin-splints and tendonitis caused by repetitive force, as well as helping to reduce the possibility of incurring an exercise-related stress fracture. Thus, rebounding may be an appropriate alternative for individuals who have joint problems or have been told to avoid high-impact activities.
One final observation of rebounding exercise pertains to the choice of movements. Although rebounding choreography tends to use some single-leg impact moves such as running and step kicks, the highly fit participants in this project found those moves to be somewhat awkward to perform. Therefore, acknowledging the limitations of this project with 10 highly fit subjects, it still seems prudent to recommend choreography on the rebounder that involves predominantly a double-leg impact style.
Rebounding can readily be incorporated into a fitness routine for most physically active people. It may be used as an alternative to regular workouts and may be beneficial in attracting clients who might choose not to otherwise participate in aerobic classes. It may also be useful when attempting to avoid overuse injuries or when combating exercise boredom. Many movements can be added to make the exercise more sport-specific. For example, side-to-side hops mimic movements found in skiing. Another option would be to include rebounding in circuit training or cross- training programs.
Table 2. Summary of Results*
VO2 (ml(Kg-minr)-1) 30.24 ± 5.6 28.73 ± 4.3
HR (BPM) 157.5 ± 25.5 155.3 ± 26.2
VE(L/min) 46.09 ± 15.3 47.19 ± 10.9
RER (VCO./VO^ .92 ± 0.4 .93 ± .05
Energy Expenditure 10.07 ± 3.0 9.45 ± 1.8
* Values tire means ± standard deviation
Benefits of rebounding include increased cardiorespiratory fitness levels, caloric expenditure, and possibly improved kinesthetic awareness. Rebounding is a low-impact physical activity. This low-impact benefit may be beneficial in reducing overuse injuries, which are often associated with other types or exercise such as logging and running.
Condensed Version and Bottom Line
This study indicates that rebounding may be considered a good exercise mode for improving aerobic fitness and for inclusion in weight management programs. It may also be an alternative for people who may need to stay away from traditionally high-impact activities such as running and other styles of impact aerobics. This fitness alternative can be easily worked into the fitness routines of clients with varying fitness levels and abilities. For those looking for a nontraditional way to spice up a routine, rebounding may be the answer.
Rebounding program and equipment resources
Colleen A. McGlmie, B.S., is currently pursuing an M.S. in Exercise Science and. Sports Administration at the University of New Mexico. Her research interests include modality testing/comparison and muscular strength and conditioning. She is ACSM Health/Fitness Instructor, and NSCA Physical Trainer certified. Len Kravitz, Ph.D., has a doctorate in health promotion and exercise science. He is an Assistant Professor and Researcher at the University of New Mexico, where he serves as the Coordinator of Exercise Science. Kravitz was recently awarded the Canadian Fitness Professionals "International Presenter of the Year" award.
Jeffrey M. Janot, Ph.D., EPC, is an Assistant Professor of Exercise Physiology in the Department of Athletics at South Dakota State University. Currently, his research focuses on the cardiovascular responses during exercise in healthy and clinical populations, body composition in special populations, and fitness product testing. Dr. Janot is also ACSM Exercise Specialist® certified and Exercise Physiologist certified from the American Society of Exercise Physiologists.
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