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Original Research

Effect of the Power Balance® Band on Static Balance, Hamstring Flexibility, and Arm Strength in Adults

Verdan, Princess J.R.; Marzilli, Thomas S.; Barna, Geanina I.; Roquemore, Anntionette N.; Fenter, Brad A.; Blujus, Brittany; Gosselin, Kevin P.

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Journal of Strength and Conditioning Research: August 2012 - Volume 26 - Issue 8 - p 2113-2118
doi: 10.1519/JSC.0b013e31823a43ce
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The optimal control of balance, coupled with increased strength and better flexibility, is an essential requirement for the successful accomplishment of a variety of human behaviors (10) and practices, from sports and daily activities to the prevention of injury (1). For a better understanding of the concept of balance, Bressel et al. (3) suggest that some of the factors that influence balance are sensory information obtained from the visual, vestibular, and somatosensory systems and motor responses that affect joint range of motion, coordination, and strength. Also, Anderson and Behm (1) suggest that balance is accomplished through the interaction of central anticipatory and reflexive actions and the passive and active restraints imposed by the muscular system.

Achieving optimal control of balance, increased strength, and better flexibility are gaining paramount importance in a world of technological advancements, human performance, and medical discoveries. It is no wonder that there is a never-ending attempt to create new products designed to improve such essential conditions. For the past few years, various wristbands have invaded the market professing to enhance poor balance, strength, and flexibility, including EFX Bracelet, iRenew, Phiten X30 Healthy Bracelet, and the Power Balance® band (5,9,17,18).

For this study, the Power Balance® band was used because of its popularity and many endorsements by professional athletes. According to (18), “we want everyone, no matter their level of activity, to maximize their potential and live life to the fullest through the use of a new and revolutionary technology, the Mylar hologram.” The Mylar hologram, treated with energy waves and placed within a silicon band, is meant to carry that electromagnetic (EM) field of energy (18). Rein (19) suggests that duplicating the natural dynamic frequency patterns within an externally applied EM field carrier could be used to treat the body. According to Layng (12), holograms have shown to be useful in the market place and are being used in credit cards and labels for security reasons and are found on food boxes, magazine tip-ins, book covers, tickets, and currency; however, the following question arises: “What effect, if any, can a Mylar hologram have on the body's energy flow?”

With this question in mind, the authors of this study questioned the validity and effectiveness of the Power Balance® Company's tests, which are done during advertisement. Although the company conducts 4 tests—the first test always without the band, whereas the second one with the band—it does not control for learning effect, fatigue, or placebo, and it does not prove that the Mylar hologram has an effect on the body's energy flow. According to the company's website, they are yet to conduct scientific research to prove the effects of the band (18). The authors of this study could only find one pilot study that was performed to determine the effectiveness of the holographic balance band with regard to improved balance, flexibility, and strength. The independent pilot study was conducted for the American Council on Exercise by exercise physiologists at the University of Wisconsin at LaCrosse. The double-blinded study hypothesized that the balance bands would be ineffective (22). Although the pilot study demonstrated that there was no positive effect of the balance band on any of their performance tests, because the order of the tests was not counterbalanced, this study did demonstrate a significant testing effect, demonstrating that whichever test was conducted second, performance was significantly better than that of the first time. This research study not only uses objective performance tests, but the order of these tests were also counterbalanced to control for any possible testing effects.

The purpose of this study was to investigate the effects of wearing Power Balance® bands on: (a) balance, (b) hamstring flexibility, and (c) arm strength. This article aimed to answer the specific research question: whether wearing the Power Balance® band improves balance, flexibility, and strength as suggested and published in the item's literature. It was hypothesized that the balance bands would have no effect on balance, flexibility, and strength.


Experimental Approach to the Problem

The primary focus of this experiment was to determine the effects of the Power Balance® bands on strength, flexibility, and balance. To control for a testing effect, the subjects were assigned to 3 groups in which the order of the treatment was randomized. Each subject performed all tests in 1 day.


The subjects who participated in the study are part of the demographic group targeted by Power Balance®. The subject group consisted of 24 (10 men and 14 women) undergraduate students from the Department of Health and Kinesiology at the University of Texas at Tyler with an average age of 22 ± 2 years.

The Institutional Review Board's approval was granted by the University of Texas at Tyler, and all the subjects were found to be free from any risk factors as defined by the American College of Sports Medicine's Guidelines for Exercise Testing and Prescription and were therefore classified as Class A subjects: Apparently healthy individuals. All the subjects signed informed consent forms before testing.


Testing of balance was done on the BIODEX System SD. The sway index was used as a determinant of balance. This measurement represents the postural sway of the subjects from the center point on which they stand. The specific test used on the BIODEX was the Clinical Test of Sensory Integration and Balance (m-CTSIB). The test required that the subjects remain in a stationary position under 4 conditions: (a) with eyes open on a firm surface (EOFS), (b) eyes closed on a firm surface (ECFS), (c) eyes open on a foam surface (EOFoS), and (d) eyes closed on a foam surface (ECFoS).

The MicroFit System was used during the experiment to test the subjects for strength and flexibility. The MicroFit System is a computerized assessment of different fitness components. Performance of an individual can be directly recorded and compared with those of the previous attempts. It also provides a more objective analysis of performance. The tests included a biceps strength test and a sit-and-reach test. The results of each test were recorded electronically. The apparatus for the biceps strength test was a platform with a curl bar attached to it via tether. The apparatus for the flexibility test was a flexometer consisting of a long touch sensitive board with measurements ranging from 1 to 70 cm. At the 40-cm mark, the board diverged into 2 heel placement areas.


This was a double-blind, placebo controlled study. All the 24 subjects were tested for each of the company's proposed benefits (balance, flexibility, and strength). As can be seen in Figure 1, the subjects were tested wearing a Power Balance® band with the hologram removed, a Power Balance® band, and no band (control). A sweatband was used to cover the band in order to blind the subjects and the test administrators to the conditions.

Figure 1
Figure 1:
Power Balance® bands with and without the Mylar hologram.

A 5-minute warm-up consisting of jogging in place, lunges, hamstring stretch, quadriceps stretch, and a lower-back stretch was performed before testing. Each stretch was done twice holding for 10 seconds.

The subjects were assigned to 3 different orders with 3 experimental sessions for each order. Table 1 represents the order in which the subjects wore the bands. The order of the experimental sessions was counterbalanced across the subjects to prevent fatigue and learning effects from confounding the results. Fatigue is shown to decrease postural stability (6). A waiting period of approximately 2 minutes between treatments was necessary to switch bands. Also, there was a waiting period of approximately 2 minutes between the balance test and the MicroFit Test.

Table 1
Table 1:
Bands by order.*†‡

Strength Testing

Before strength testing, the subjects performed 1 practice session to familiarize themselves with the equipment. The subjects performed 3 tests per session. The highest score was used for analysis in accordance with the FitnessGram protocol. For the bicep strength test, the subjects stood on the MicroFit board with a biceps curl bar attached by a tether. Length was adjusted for each subject to ensure that the starting position was with elbows bent at 90°. When given the signal, the subjects were instructed to contract with maximum force during the biceps curl to facilitate the most accurate readings of strength. The score was recorded by the MicroFit.

Flexibility Testing

Flexibility testing was conducted using the same protocol as that of strength testing (i.e., 1 practice test followed by 3 tests per session). The highest score was used in statistical analysis. The subjects sat on the floor with feet fully outstretched and heels touching the apparatus. Measurement was taken using standard sit-and-reach protocol with 1 exception: the electronic system required the subject to hold the outstretched position for 4 seconds to facilitate a reading.

Balance Testing

The subjects were allotted a practice test to familiarize themselves with the BIODEX. The subjects were told to stand as still as possible. During the first part of the session, they stood on a firm surface with their eyes open for 30 seconds. Next, the subjects were asked to stand for 30 more seconds with their eyes closed. During the second part of the session, a foam insert was placed on the floor of the machine that had identical surface markers inscribed on it. The surface markers were lined up with those on the firm surface of the balance machine. The insert increased the level of difficultly. Following the previous procedures, the subjects stood as still as possible for 30 seconds with their eyes open and then for 30 seconds with their eyes closed. Each condition was followed by a 10-second break. The data were produced electronically by the balance machine.

Statistical Analyses

Three separate mixed factor analysis of variance with repeated measures were used to measure strength (3 order × 3 treatment), flexibility (3 order × 3 treatment), and balance (3 order × 3 treatment × 4 condition). In cases where the sphericity was violated, Greenhouse-Geisser Epsilon degrees of freedom were used. The locus of any significant effects was identified by the least significant difference pairwise comparisons variables. An alpha level was set at p ≤ 0.05.



There were no significant differences (Figure 2, Table 2) in the treatments used (Placebo band: 28.54 ± 14.05 kg; Power Balance® band: 27.79 ± 14.12 kg; Control band: 28.17 ± 14.66 kg; F2,42 = 0.941; p = 0.398; η2 = 0.043; power = 0.202) or order effect (order 1: 26.13 ± 11.53 kg; order 2: 31.29 ± 17.96 kg; order 3: 27.08 ± 11.86 kg; F2,21 = 0.281; p = 0.757; η2 = 0.026; power = 0.089) while performing the strength test.

Table 2
Table 2:
Strength, flexibility, and sway index values for each treatment.*
Figure 2
Figure 2:
Average strength values per treatment. The SDs can be found in Table 2.


There were no significant differences (Figure 3) in the treatments used (Placebo band: 44.40 ± 9.39 cm; Power Balance® band: 44.25 ± 9.38 cm; Control band: 44.38 ± 9.24 cm; F2,29.03 = 0.220; p = 0.810; η2 = 0.01; power = 0.077) or order effect (order 1: 45.75 ± 6.97 cm; order 2: 45.71 ± 11.00 cm; order 3: 41.67 ± 8.97 cm; F2,21 = 0.489; p = 0.620; η2 = 0.045; power = 0.119) while performing the flexibility test.

Figure 3
Figure 3:
Average flexibility values per treatment. The SDs can be found in Table 2.


There were no significant differences (Figure 4) in the treatments used (Placebo band: 1.07 ± 0.67; Power Balance® band: 1.08 ± 0.72; Control band: 1.11 ± 0.76; F2,42 = 1.214; p = 0.307; η2 = 0.055; power = 0.251) or order effect (order 1: 1.05 ± 0.67; order 2: 1.13 ± 0.73; order 3: 1.09 ± 0.73; F2,21 = 2.92; p = 0.749; η2 = 0.027; power = 0.090) while performing the balance test. A significant difference (Figure 5, Table 3) was found between the different balance conditions (F1.684,35.355 = 326.417; p = 0.000; η2 = 0.940; power = 1.0). Pairwise comparisons revealed there were significant decreases in balance scores across each of the 4 conditions (EOFS: 0.51 ± 0.16, ECFS 0.68 ± 0.19, EOFoS 0.99 ± 0.25, and ECFoS 2.18 ± 0.46).

Table 3
Table 3:
Condition values for sway index.*†
Figure 4
Figure 4:
Average balance sway index values per treatment. The SDs can be found in Table 2.
Figure 5
Figure 5:
Average sway index values per condition. The SDs can be found in Table 3.


The stepped-up consistency version for determining intraclass correlation coefficients was conducted for each of the testing methods (strength, flexibility, and balance). This approach aims to delineate the proportion of variance of an observation because of between-subject variability in the true scores. The total mean scores across 3 separate ratings from each test administrator was ICC = 0.92 indicating very high interrater reliability.

Reliability analysis was also undertaken to determine the internal consistency across each of the test conditions using Cronbach's coefficient alpha (Cronbach, 1984). The higher the Cronbach's alpha, the more reliable the test is. Alpha values >0.70 indicated satisfactory internal consistency. Analyses of the coefficient alphas across the study measures were 0.99 (strength), 0.99 (flexibility), 0.76 (EOFS), 0.71 (ECFS), 0.84 (EOFoS), 0.83 (ECF0S), and 0.88 (across all balance conditions), each value indicating satisfactory reliability.


The purpose of this study was to examine the effects of wearing a Power Balance® band on balance, hamstring flexibility, and arm strength. The results from this study demonstrated that wearing a Power Balance® band has no effect on balance, hamstring flexibility, or arm strength. As hypothesized, a significant difference between treatments in each category was not seen. Each test was performed consistently, and the scores on the test did not differ. This was also shown in the research done by the investigators at the University of Wisconsin at LaCrosse.

The University of Wisconsin- LaCrosse used the same tests done by Power Balance® in their advertisements and did not find any significant results. Unlike this study, the order effect was not controlled for. During an interview conducted by Terry Rindfleisch for LaCross Tribune, John Porcari, a professor of exercise and sports science at the University of Wisconsin-LaCrosse, stated that the subjects in his pilot study wore the Power Balance® band first during each round of testing and a placebo band later (21). This procedure was the reverse of the Power Balance® Company's testing procedure conducted during advertisements for the band. The results for the Wisconsin-LaCrosse study showed that all subjects performed better during the second part of testing (21). Porcari also states, “It's no surprise the subjects did better the second time because there is a learning curve and now you know the test and you perform better” (21). This explanation clarifies as to why band wearers perform better when wearing the Power Balance® band during the company's advertisements. Some supporters of Power Balance® band purport that the increase in balance, flexibility, and strength is because of the placebo effect rather than because of the band's energy flow (22). Porcari concluded that the wristband “really shows the power of the placebo effect” (21) referring to the findings of his study. According to Clark et al. (4) and Beedie and Foad (2), a placebo effect is a positive outcome resulting from the belief that one has received a beneficial treatment. There were no placebo effects found in this study, thereby further diminishing the possibilities of the Power Balance® bands even producing a placebo effect.

The results of this study showed that there was a significant difference between the various balance treatments. It was hypothesized that there would be a significant difference between the sway scores for each treatment. The sway index of the subjects was thought to increase as the balance treatments increased in the degree of difficulty. That being said, each balance condition had a significantly greater sway index than it did in the condition before it. Increased balance-treatment difficulty led to increased difficulty for the subjects to maintain balance. This indicates that a person is more stable and less likely to sway when standing on a firm surface with eyes open than when standing on a firm surface with eyes closed, a foam surface with eyes opened, or a foam surface with eyes closed.

Wu and Chiang (23) and Fransson et al. (7) suggest that one of the simplest ways to enforce increased demand on the postural control system is to have the subject stand on a compliant foam surface. “Afferent information is obtained from visual, vestibular, and somatosensory receptor systems and processed by the central nervous system to determine the current position and movement of the body, thereby allowing precise postural control responses” (7,16,20). Thus, closing the eyes leads to increased difficulty in postural control because the body lacks in visual senses, which is more dominantly used by most individuals, to maintain good balance. The lack of visual senses forces the body to use proprioception and vestibular senses to maintain balance.

To the knowledge of the authors of this study, little scientific research has been conducted on the effects of the Power Balance® band and other products of its kind on the performance of athletes and the general public, when wearing these bands. Additionally, the Mylar hologram, which is said to emit energy, may need testing to determine its effects on the human body.

Practical Applications

Power Balance® bands were not shown to improve any of the major parameters related to sports performance (balance, flexibility, strength). Individuals desiring to achieve optimal control of balance, increased strength, and better flexibility should focus on improving these factors in proven ways (i.e., resistance training, aerobic activities) rather than through the wearing of wristbands. Although the creators of the Power Balance® band purport that the bands work regardless of the condition, placebo or otherwise, they should note that no such effects were observed in this study. In conclusion, people who wear these bands should be under no pretense that the band will improve athletic performance.


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            Mylar hologram; wristband; ergogenic aid; biceps curl

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