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|Year : 2021
: 23 | Issue : 108 | Page
|Music level preference and perceived exercise intensity in group spin classes
Lawrance Lee1, Benjamin Shuster1, Yang Song2, Sharon G Kujawa3, Didier Depireux4, Ronna Hertzano5
1 Department of Otolaryngology, Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA
2 Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
3 Eaton-Peabody Laboratories, Massachusetts Eye & Ear, Boston, Massachusetts,Department of Otolaryngology, Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, USA
4 Otolith Labs, Washington DC, USA
5 Department of Otolaryngology, Head and Neck Surgery,Institute for Genome Sciences,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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|Date of Submission||04-Jan-2020|
|Date of Decision||27-Feb-2020|
|Date of Acceptance||03-Jul-2020|
|Date of Web Publication||22-Mar-2021|
Context: Sound levels in fitness classes often exceed safe levels despite studies that show many participants find high sound levels stressful. Aims: The objective is to determine if lower sound levels in spinning classes significantly impact exercise intensity and to determine if class participants prefer the music played at lower levels. Settings and Design: Observational study of 1-hour group spin classes. Methods and Materials: Sound levels were measured in 18 spin classes over two weeks. No adjustments were made in week-1 and sound levels were decreased by 3 dB in week-2. Participant preferences and data on post-class hearing changes were collected via post-class questionnaires (n = 213) and divided into three terciles based on the total sound exposure of corresponding classes. Statistical Analysis Used: Unweighted survey generalized linear models are used to sort the causal relationships between different variables simultaneously and participant responses. The Chi-square test is used to reveal statistically significant relationships between two or more categorical variables. Results: When mean sound levels exceeded 98.4 dBC, respondents were 23 times more likely to report the music as too loud than too quiet (P < 0.05), and four times more likely to prefer a decrease, rather than an increase, in sound level (P < 0.05). There was no significant difference in respondents reporting high exercise intensity between the middle (95.7–98.1 dBC) and upper (98.4–101.0 dBC) terciles, 67.1% and 71.8%, respectively (P = 0.53). Overall, 25.9% of respondents reported auditory symptoms following classes. Analysis in the context of dBA and dBC produced congruent conclusions and interpretations. Conclusions: Sound levels in many fitness classes remain dangerously high. However, music level can be lowered without a significant impact on perceived exercise intensity and many participants prefer lower sound levels than current levels.
Keywords: Exercise intensity, fitness class, music level, noise-induced hearing loss, noise exposure, recreational noise exposure, sound level
|How to cite this article:|
Lee L, Shuster B, Song Y, Kujawa SG, Depireux D, Hertzano R. Music level preference and perceived exercise intensity in group spin classes. Noise Health 2021;23:42-9
Music levels in fitness classes often exceed safe levels under the belief that loud music is a significant motivating factor. However, prior studies show that many participants find the music levels stressful, and the present study demonstrates that music levels can be reduced without significant impact on exercise intensity.
| Introduction|| |
According to the World Health Organization (WHO), disabling hearing loss afflicts approximately 466 million people worldwide, and the number of affected individuals is estimated to grow to over 900 million by 2050. Two common causes of acquired hearing loss are genetics and environmental factors such as noise exposure., The US government agencies regulate noise exposure intensity and durations in occupational settings to reduce the prevalence of noise-induced hearing loss. However, recreational and leisure noise exposures are considered a matter of choice; thus, these exposures are not subject to this type of regulation and often reach unsafe levels.,, For example, although employers of entertainment venues must comply with Occupational Safety and Health Administration (OSHA) regulations for their employees, government and international agencies, like the United States Environmental Protection Agency (EPA) and WHO, are only able to provide guidelines to these venues regarding the noise exposure of patrons.
Group fitness classes are one example of a recreational setting in which sustained levels of sound often reach unsafe levels and may negatively impact hearing. Prior studies show that mean sound levels in group fitness classes such as high-intensity classes frequently exceed 90 dBA and often exceed 100 dBA., The National Institute of Occupational Safety and Health (NIOSH) recommends that a noise exposure of one hour, a common duration of group fitness classes, not exceed a mean level of 94 dBA, whereas exposures to levels of 100 dBA should be limited to less than 15 minutes. These constraints are often not met in the setting of group fitness classes.
One argument for increasing music levels in fitness classes is that participants and instructors believe exercise performance and motivation are positively impacted by increasing music level. Although this may hold some truth, studies investigating the connection between music and exercise performance demonstrate that other factors, such as the tempo of the music or just the addition of music alone, have a greater role in positively impacting exercise performance and motivation., Furthermore, additional studies demonstrate that, in some instances, over one-quarter of fitness class participants find the current sound levels stressful.10
To the best of our knowledge, no prior studies have collaborated with fitness centers to adjust the music level in fitness classes to safer levels and evaluate how a wide range of sound levels in classes correspond to participant preferences for music level and perceived exercise intensity. In the present study, we partnered with a local fitness center to lower sound levels in classes and compared music level preferences and perceived exercise intensity at different sound levels during classes. The goal was to investigate if lower sound levels in spinning classes have a significant impact on exercise intensity compared to higher sound levels and to determine if class participants prefer the music played at lower levels.
| Subjects and methods|| |
The study obtained an exemption status by the Institutional Review Board at the University of Maryland, Baltimore (protocol HP-00083820). This study was conducted at a local fitness center in Baltimore, Maryland. Gym management approved the study design prior to initiation. Researchers informed fitness instructors that sound levels would be monitored during the study but did not provide additional details. We selected a series of 1-hour spin classes that took place in the same fitness classroom to control for class intensity, acoustic space, and the type of music played. In total, there were six unique instructors that were coincidentally all female.
During week-1 of data collection, no adjustments were made to sound levels during classes. During week-2 of data collection, the master system controlled only by gym management was decreased by 3 dB (the reduction agreed upon by the gym), extending the range of the measured sound levels in the spin classes to lower levels. Spin class participants voluntarily completed the study questionnaire following each class during both weeks of data collection.
Sound level measurement
An Optimus Red sound level meter (SLM) (Model CR:162B) (Cirrus Research, United Kingdom), an ANSI-compliant class 2 SLM, calibrated with a Cirrus Acoustic Calibrator (Cirrus Research, United Kingdom) recorded class sound levels. The SLM was mounted to a tripod and placed at chest level at the same location in the studio for all recorded classes. The SLM was angled toward the right-front speaker and measurements were collected for the full class duration using a fast-response setting to sample the environment eight times per second. Preliminary acoustic measurements throughout the studio space demonstrated that sound levels did not deviate more than ±2 dB from the selected location of sound measurement.
An equal-loudness contour, sometimes also referred to as Fletcher-Munson contour, represents sound pressure levels necessary at each frequency to produce the same perceived loudness. An A-weighted filter, based on the 40-phon contour, is most representative of the human ear response to sound levels below 60 dB, as it attenuates the impact of lower frequencies. In contrast, the C-weighted filter approximates the 100-phon contour. Additionally, OSHA notes that C-weighted filter is used particularly for measuring low-frequency sound capable of inducing vibrations, fitting the description of the percussive, low-frequency driven music often used in spin classes. Thus, we believe it to be more applicable in the loud environment that this study measures. For these reasons, we primarily present sound levels as C-weighted equivalent continuous sound levels (LCeq). However, we recognize that A-weighted measurements are standard, and we therefore also display A-weighted equivalent continuous sound levels (LAeq) to compare measurements to NIOSH guidelines. Additionally, we have analyzed respondents’ perceived loudness, sound level preference, and exercise intensity in terciles corresponding to A-weighted measurements, which can be found.
Participants were notified of the study by instructors but were not provided details or objectives of the study and voluntarily completed the 10-question survey following each class [Supplement Figure 1]. The survey did not include identifying information such as name or date of birth to maintain participant anonymity. Participants who attended multiple classes during the study were encouraged to complete a survey after each class attended.
|Figure 1 Sound level in LAeq and LCeq of each fitness class stratified by class sound level (LCeq) (red line denotes mean). LAeq, A-weighted equivalent continuous sound level; LCeq, C-weighted equivalent continuous sound level.|
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A review of LCeq values across classes revealed a wide range from 93.2 to 101.0 dBC, with significant overlap in measured sound levels between week-1 and week-2. Therefore, to better correlate sound levels to survey responses, classes, and corresponding survey responses from both weeks were collectively stratified into three groups based on LCeq, versus directly comparing data between the two weeks. In addition, very few respondents reported scores of 1 or 5 on the questionnaire. Thus, scores of 1 and 2 as well as scores of 4 and 5 were grouped during data analysis.
The lower tercile of classes ranges from 93.2 to 95.6 dBC, the middle tercile from 95.7 to 98.1 dBC, and the upper tercile from 98.4 to 101.0 dBC. It is crucial to recognize that although there is “only” a 2 to 3 dB difference between the ranges of each tercile, the logarithmic, rather than linear, scale of decibels means that a 3 dB increase doubles the intensity of sound. Data collected and stored by the SLM and survey responses corresponding to each class were exported and organized using Windows Microsoft Excel 2016 (Microsoft, Washington). All the statistical analyses and plots were generated using R version 3.5.0 (R Foundation for Statistical Computing, Austria). To determine how other factors might account for variance in perceived loudness, sound level preferences, and perceived exercise intensity, we used the regression function “Survey-Weighted Generalized Linear Models” of the svyglm package in R version 3.5.0. P-values were calculated using the regTermTest (chi-square test) to test for significant relationships between two categorical variables. Statistical significance was determined using an α-level of 0.05.
| Results|| |
Sound levels were recorded in 18 available classes during the study − ten in week-1 and eight in week-2. [Figure 1] displays both LAeq and LCeq measurements of the classes. NIOSH recommends that levels during 1-hour exposures not exceed 94 dBA. In total, 15 classes were in accordance with NIOSH recommendations, whereas three classes exceeded levels recommended by NIOSH for a 1-hour period. Although measurements in dBA determine whether classes are in compliance with NIOSH recommendations as previously discussed, measurements in dBC are more reflective of human auditory perception at a high sound level.
Participant population and music level preferences
A total of 213 surveys were completed, with 124 in week-1 and 89 in week-2. The mean age of respondents was 31.9 years. Eighty-two percent of respondents fell between ages 21 and 40. Respondents ages 21 to 30, 31 to 40, and greater than 40 years of age attended on average 3.3, 3.1, and 3.8 classes per week, respectively (P = 0.09). Thirty-two percent of respondents ages 40 years or older reported the music level as too loud, almost twice as many compared to 18.2% of respondents ages 31 to 40 years and 17.3% of respondents ages 21 to 30 years (P = 0.11) [Figure 2]a.
|Figure 2 Participant perception of loudness stratified by age (a) and biological sex (b). LCeq, C-weighted equivalent continuous sound level.|
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Sixty-nine percent of respondents identified female as their biological sex [Table 1]. Both males and females reported attending on average 3.3 classes per week (P = 0.48). [Figure 2]b stratifies perceived loudness by sex and demonstrates no statistical difference between male and female respondents regarding perception of loudness (P = 0.701).
Impact of measured sound level on music level preferences
[Figure 3]a displays respondent perception of music loudness stratified by class sound level. In the upper tercile (n = 72), respondents were 23 times more likely to report music level as too loud rather than too quiet (P < 0.05), with 32.4% reporting the music level as too loud (selecting 4 or 5 on the questionnaire), 1.4% reporting the music level as too quiet (1 or 2), and 66.2% reporting the music level as satisfactory (3). Comparatively, in the lower tercile (n = 61), 79.6% of respondents reported the music level as satisfactory − a 13.4% increase compared to the upper tercile (P = 0.15). Additionally, 11.1% of individuals in the lower tercile reported the music level as too quiet (1 or 2) and 9.3% reported music level as too loud (4 or 5; P = 0.18).
|Figure 3 Perceived loudness (a) and sound level change preference (b) stratified by class sound level (LCeq). LCeq, C-weighted equivalent continuous sound level.|
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[Figure 3]b displays respondents’ preference for music level. Respondents in the upper tercile were 3.8 times more likely to prefer decreasing rather than increasing the music level (P < 0.05) − 32.4% and 8.5%, respectively. Comparatively, respondents in the lower tercile were 2.6 times more likely to prefer increasing rather than decreasing the music level (P < 0.05) − 24.1% and 9.3%, respectively. Additionally, the percentage of respondents reporting that they would not change the music level (3) decreased from 66.7% in the lower tercile to 59.2% in the upper tercile (P = 0.39).
Impact of measured sound level on exercise intensity
[Figure 4] displays respondents’ perceived exercise intensity stratified by the same three terciles based on LCeq. Between the middle and upper terciles, there was no significant difference in the percentage of respondents who reported high exercise intensity (4 or 5) − 67.1% and 71.8%, respectively (P = 0.53). In the lower tercile, 48.2% of respondents reported high exercise intensity, a decrease of 18.9% and 23.6%, respectively, from middle and upper terciles (P < 0.05, P < 0.05, respectively). Two respondents in the lower tercile reported low perceived exercise intensity (2), while one respondent in the middle tercile and no respondents in the upper tercile reported this. No respondents during the study perceived exercise intensity as very low (1).
|Figure 4 Perceived exercise intensity stratified by class sound level (LCeq). LCeq, C-weighted equivalent continuous sound level.|
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Impact of ringing or muffled hearing on sound level preferences
Respondents were asked if they have experienced ringing in their ears, muffled hearing, or both, after attending fitness classes in the past. One quarter of respondents reported one or both symptoms in the past. Of the respondents who preferred increasing music levels in classes, only 16.3% reported symptoms in the past. In contrast, 43.6% of respondents who preferred lowering music levels reported symptoms in the past (P = 0.09) [Figure 5]. Although nearly a quarter of respondents reported symptoms, only three respondents, or 1.4% of those surveyed, reported using earplugs during class, and one of the three respondents reported symptoms after classes in the past.
|Figure 5 Self-reported history of muffled hearing, ringing in ears, or both stratified by sound level change preference.|
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Results in the context of A-weighted measurements
Analysis of the data produces similar results and trends when classes are grouped into terciles according to LAeq (using an A-weighting) rather than LCeq as described above.
In the context of dBA, respondents in the upper tercile were more than twice as likely to report the music as too loud rather than too quiet (P < 0.05). Additionally, 15.8% more respondents report satisfactory music level in the lower tercile compared to the upper tercile (P = 0.07), a greater increase than that seen in the context of dBC [Supplement Figure 2].
Furthermore, although our data in the context of dBC revealed a significantly lower percentage of respondents reporting high exercise intensity in the lower tercile compared to the middle and upper terciles, our data in the context of dBA demonstrate that, between all three terciles, there was no significant difference in the percentage of respondents reporting high exercise intensity (P=0.59), and no significant difference in respondents reporting average exercise intensity (P = 0.70) [Supplement Figure 3]. These data provide additional evidence that music levels can be decreased to safer levels without a negative impact on self-reported exercise intensity.
Analysis of the data in the context of dBA and dBC produced congruent conclusions and interpretations. Minor differences between the two sets of analyses can be attributed to differences in the frequency composition of the music played between classes. Stratification of classes into terciles using either LAeq or LCeq produced similar, but not identical, terciles.
| Discussion|| |
The data collected from this study confirm the conclusions from previous studies demonstrating that music in group fitness classes often exceeds safe levels. The mean LAeq approached the threshold considered safe for a one-hour duration according to NIOSH, and A-weighted levels in three of the 18 classes sampled exceeded NIOSH recommendations. However, the measured LCeq is consistently a greater value than the measured LAeq of the same class. As discussed previously, C-weighted measurements more accurately reflect the response of the human ear at higher sound levels compared to A-weighted measurements. This suggests that participant exposures and potential sequelae from those exposures are possibly underestimated using the current A-weighted standards of measurement.16 It is also worth noting that class instructors teaching multiple classes per week are subjected to longer exposure times and greater risk.
Additional support of the conclusion that music levels in group fitness classes remain dangerously high is demonstrated by the data showing that nearly one quarter of survey respondents reported ringing in their ears or muffled hearing following a class. Interestingly, although respondents who reported symptoms following a past class were approximately three times as likely to prefer decreasing the music level, only one respondent reported using hearing protection during classes. Perhaps respondents do not recognize the correlation between symptoms following intense exposure and the potential hearing damage or potential temporary hearing threshold elevation. Equally challenging from a public health perspective is the possibility that respondents are aware of the potential hearing damage but disregard the potential consequences. In fact, some studies have demonstrated that many individuals are aware of the potential for hearing loss due to recreational noise exposure yet fail to use hearing protection offered at fitness centers or take other preventative measures.
Recent research also demonstrates that the peripheral auditory system is particularly susceptible to noise injury, and that significant hearing damage may precede clinically detectable elevations in hearing thresholds.,,,,,, The inability to clinically detect damage to the peripheral auditory system prior to hearing threshold elevation presents additional obstacles to public health initiatives designed to reduce hearing loss from recreational noise exposure.
Our data also confirm the findings of previous studies demonstrating that a significant fraction of fitness class participants perceives the music as too loud. More crucially, the data also support our hypothesis that participants prefer the lower sound levels. In the tercile of classes with the highest sound levels, 32.4% of respondents reported that the sound level was too high, and 32.4% of respondents reported that they would prefer a decrease of the music level. In contrast, respondents were most likely to respond that music level was satisfactory in classes where sound levels were lowest. There is a near-even distribution of respondents who perceived the music level as too loud versus too quiet in the lower and middle terciles, while the distribution is heavily skewed in favor of those who report the music level as too loud in the upper tercile. These findings are critical in creating a dialogue with fitness centers management globally, as they not only suggest that lower sound levels in classes are beneficial to hearing health, but also that lower sound levels may improve gym member satisfaction.
Previous studies also demonstrate a positive correlation between music level and exercise intensity. This link provides some rationale for the use of high music levels in group fitness classes. Our data also suggest a positive correlation between music levels and perceived exercise intensity. Respondents in the lower tercile were the least likely to report above-average perceived exercise intensity. However, the data also suggest that the positive impact of music level on perceived intensity diminishes when a certain music level is reached. This diminishing return is demonstrated by the negligible difference in perceived exercise intensity reported by respondents in the middle and upper terciles. Importantly, only three respondents rated their perceived exercise intensity as below average during the study. Thus, we believe that a decrease in sound levels in group fitness classes can be achieved without a significant reduction in perceived exercise intensity.
There are limitations to this study. With a relatively small sample size of 213 respondents all surveyed at a single location, the study may not fully reflect the general population. The lack of identifiers on surveys also prevented the ability to determine if the data were skewed by responses from respondents who attended multiple classes and submitted multiple surveys. Additionally, while stratifying the entire data set into three groups provided a clearer image of how respondents characterized sound levels and demonstrated a preference for lower sound levels, a conclusion cannot be drawn about the direct effects the intervention to lower sound levels in week 2 had on respondent responses. Lastly, when surveying a population in a recreational private facility such as a gym, one must consider numerous factors that are less commonly encountered in traditional clinical research. In particular, the study design must have minimal to no negative impact on the gym workflow or experience. For this reason, the gym management agreed upon a 3 dB reduction in sound levels during the second week of data collection but did not agree to the originally proposed 6 dB reduction in sound levels.
In future studies, biometric data can be utilized to objectively quantify the effect of music level on exercise intensity or motivation rather than depend on the subjectivity of surveys that have been used in prior studies and the present study. Many fitness centers have already adopted technologies such as monitors measuring heart rate, caloric output, and the number of steps that allow for an objective measurement of exercise intensity.
On a final note, although spin classes are one source of significant noise exposure, many patrons of fitness centers choose to exercise individually, while listening to music or watching videos through a personal audio device. The noise exposure caused by these devices is another source of noise exposure that was not explored in this study. Like the noise exposure in group fitness classes, exposures from these devices are difficult to measure and regulate. Organizations such as the International Electrotechnical Commission have attempted to limit excessive noise exposure while using personal audio devices by implementing warning labels on devices capable of generating more than 85 dBA or actively informing users of increased sound levels with pop-up messages. Some regulations have been implemented in the European Union, but no regulations related to the recreational use of personal audio systems are currently in place in the United States. The lack of regulations and the inability to enforce these regulations highlights the importance of educating the public about the relationship between excess noise exposure and noise-induced hearing loss.
| Conclusion|| |
To our knowledge, the present study is the first cooperation with a fitness center that reduces sound levels in group fitness classes to observe how a wide range of sound levels correspond to participant preferences for music level and perceived exercise intensity. The data collected show that sound levels in fitness classes remain dangerously high and that participants prefer lower sound levels. An alarming number of respondents also reported experiencing ringing in their ears or muffled hearing following fitness classes. Incongruously, reported use of hearing protection during class is rare, despite the fitness center offering earplugs at their front desk. Lastly, we demonstrate that a reduction of sound to safer levels can be achieved without a significant effect on perceived exercise intensity.
We recognize that this study was conducted at a local fitness center with a limited participant number and diversity. However, these data provide an opportunity to create an open dialogue with fitness centers and urge fitness centers globally to rethink their understanding of music’s impact on the group fitness class experience. In fact, the management of the partnering fitness center noted that they maintained a lower maximum sound level after completion of the study with generally positive responses from members. We urge other fitness centers to also take steps to protect the hearing health of their members and instructors. We hope that this study can also serve as a steppingstone to engage larger fitness centers with locations nationally or internationally to participate in future studies that further explore this topic. This study could serve as a model demonstrating that such collaborations do not come as a detriment to the business, but instead have the potential to improve their business as well as hearing health. Finally, our data indicate that education about hearing health represents a public health opportunity. Installing sound level meters in fitness centers and appropriate signage correlating sound levels and use of appropriate and accessible hearing protection (e.g., earplugs from dispensers in a visible location) could be the first step toward better hearing protection.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Department of Otolaryngology, Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, Maryland, MD 21201
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]