EFFECTS OF TWO DIFFERENT AUDITORY STIMULI ...

EFFECTS OF TWO DIFFERENT AUDITORY STIMULI ON PERCEPTUAL AND METABOLIC RESPONSES DURING SUBMAXIMAL TREADMILL RUNNING

By Tiev Bartok Miller B.S., University of Louisville, 2004

A Thesis Submitted to the Faculty of the Graduate School of the University of Louisville in Partial Fulfillment of the Requirements for the Degree of

Master of Science

Department of Health and Sport Sciences University of Louisville Louisville, Kentucky

August 2006

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

UMI Number: 1438656

Copyright 2006 by Miller, Tiev Bartok

All rights reserved.

INFORMATION TO USERS

The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.

®

UMI UMI Microform 1438656 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code.

ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

EFFECTS OF TWO DIFFERENT AUDITORY STIMULI ON PERCEPTUAL AND METABOLIC RESPONSES DURING SUBMAXIMAL TREADMILL RUNNING

By Tiev Bartok Miller B.S., University of Louisville, 2004

A Thesis Approved on

IA) 2QOf/? By the following Thesis Committee:

c ro

Thesis Chair

iW- UtlUjkThesis Co-Chair(_)

>1 / L b s itiJ jA -*' Committee Member

Q&nhczrzou

ii

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

DEDICATION This thesis is dedicated to my family, friends, and mentors. I would also like to make a special dedication of this project to Mr. Ruben Hall a.k.a. “Flat Top” for the precious experiences, invaluable insight and inspirations you have shared with me. I am honored to have known you.

iii

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

ACKNOWLEDGEMENTS I would like to thank my thesis director Dr. Ann Swank for her benevolence, leadership, and trust. If not for her unwavering compassion and advocacy of my ambitions, this project would exist only as a lingering doubt in the recesses of my mind. I thank Dr. Kara Gallagher for her clemency, tutelage, gregariousness, and sensibility. Navigating academia would have proven to be a formidable task without your counsel and your personality. I would like to acknowledge the influence of Dr. Barbara Wheeler as member of my committee. You have entertained and nurtured my deep infatuation for the cross-pollination of our respective disciplines even in the absence of any profound efflorescence. I extend a special thanks to John Manire for sharing with me your elegant demeanor, charismatic wit and tremendous insight, and my peers to whom I am indebted to for the generous gift of their competitive engagement. I would like to recognize the high level of physical and artistic ability achieved by the many dancers and performance artists I have met and befriended over the course of my life. You embody music and your virtuosity reveals the humanity within our selves and in others who seek it unremittingly. Rhythm is our pulse, melody is our journey, and music is our life. To my parents Amanda and Scott, it is to you I express my deepest appreciation. For your selfless devotion to my happiness, and success, you have my gratitude. I love you both very much.

iv

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

ABSTRACT EFFECTS OF TWO DIFFERENT AUDITORY STIMULI ON PERCEPTUAL AND METABOLIC RESPONSES DURING SUBMAXIMAL TREADMILL RUNNING T. Miller June 12, 2006 Background: The perception of effort during exercise may be influenced by the situational context in which the exercise is performed and by the disposition of the exerciser. Personality type, level of motivation, and attentional focus can impact the psychological reference filter influencing ratings of perceived exertion (RPE). Understanding what factors effect exertion and result in greater exercise enjoyment may prove useful in developing strategies which promote greater adherence to structured exercise and activity performed on a daily basis. Purpose: The purpose of the study was to determine if two different forms of auditory stimuli, preferred music (PM) and subject selected audio books (AB), would exhibit differential effects on RPE and enjoyment ratings during continuous bouts of aerobic exercise. Methods: 20 subjects (10 males, 10 females) were randomized to PM and AB exercise conditions on non-consecutive days. Exercise consisted of 20 minute treadmill running bouts at 75%-85% of age predicted maximum heart rate. Workloads were identical for both stimulus conditions but differed between subjects due to variability in HR responses. RPE was collected in 5 minute intervals using a 10-point OMNI scale. Metabolic and respiratory values were collected

v

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

continuously at 30 second averages and enjoyment was assess post-exercise using a modified 10-point Likert scale. A paired samples T-test was used to determine significant differences between conditions. Results: RPE was significantly lower while perceived enjoyment was significantly greater during the PM condition (p < 0.05). However, metabolic and respiratory values were significantly greater during the PM condition indicating greater a metabolic cost at a lower RPE (p < 0.05). No significant gender differences were observed. Conclusion: Based upon the findings of the study, it is evident that different situational factors introduced during exercise, in this case PM and AB auditory stimuli, have significantly different effects on RPE, enjoyment, and various physiological parameters in apparently healthy young adult males and females. This finding maybe useful in developing strategies for promoting greater adherence to structured exercise programs in overweight, obese, and highly sedentary populations at risk for chronic health problems.

VI

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

TABLE OF CONTENTS PAGE ACKNOWLEDGMENTS..................................................................................................... iv ABSTRACT........................................................................................................................... ..v CHAPTERS I.

INTRODUCTION.................................................................................................. 1 Purpose....................................................................................................................4 Hypotheses..............................................................................................................4

II.

LITERATURE REVIEW...................................................................................... 6

III.

METHODS............................................................................................................18 Subjects................................................................................................................. 18 Procedures............................................................................................................. 19 Measures...............................................................................................................21 Statistical Analyses.............................................................................................. 23

IV.

RESULTS............................................................................................................. 25 Ratings of Perceived Exertion and Enjoyment..................................................25 Metabolic Cost and Energy Expenditure........................................................... 26 Respiration............................................................................................................27 Heart Rate.............................................................................................................28

V.

DISCUSION......................................................................................................... 32

REFRERENCES..................................................................................................................... 43 APPENDICES........................................................................................................................ 47 CURRICULUM VITAE........................................................................................................ 49

vii

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

I. INTRODUCTION

Perceived exertion is defined as the subjective intensity of effort, strain discomfort and/or fatigue that is experienced during an exercise task (38). The perception o f effort, fatigue or force during exercise may be influenced by the situational context in which the exercise is performed and by the disposition of the exerciser (38). Situational and dispositional factors such as personality type, level of motivation, and attentional focus can impact perception of exertion during exercise. The same factors that can affect perception o f exertion may also affect the degree to which exercise can be considered tolerable or the manner in which it is enjoyed. Learning what factors influence exercise exertion and result in greater enjoyment may prove useful in developing strategies which promote greater adherence to structured exercise and activity performed on a daily basis. Exercise has important health benefits which include decreasing the risk of developing heart disease, obesity and diabetes. The US Surgeon General, American College of Sports Medicine, Centers for Disease Control and Prevention, and National Institutes of Health report important health benefits are gained when 30 minutes of moderate physical activity are performed on most days of the week (1, 23, 36, 54). While physical activity in greater amounts may be required to prevent weight gain, moderate amounts o f physical activity performed on a daily basis greatly reduce the risk of cardiovascular disease and premature mortality. However, many individuals find meeting

1

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

these recommendations to be a challenging commitment. It is estimated that over 40% of the adults in America are highly sedentary and do not engage in physical activity (1). The lack o f adherence to structured exercise may be due to various situational and dispositional factors. Changing the situational and dispositional context in which exercise is performed may stimulate more long term dedication to structured exercise programs (3, 13, 18). One study demonstrated that music could be used to increase the attractiveness of a stairwell in a school of public health promoting greater usage of the stairs within the facility by faculty and students by changing its aesthetic appeal (5). Another study conducted within the field of ergonomics on efficiency performance during repetitive work tasks in industrial settings demonstrated that even background music aids in work efficiency, and productivity (17). Using music to change the context in which physical work or exercise is performed may be a viable way of positively influencing an individual’s disposition during exercise thereby enhancing the enjoyment of the experience. The current study examined two types of auditory stimuli and their effects on ratings of perceived exertion (RPE) during submaximal running bouts. The stimuli chosen for the study, preferred music (PM) and audio books (AB), are two types of auditory stimuli which have not previously been tested together and comparatively examined for their effects on perception during exercise. This study is based upon previous research which demonstrates that music may modify RPE during aerobic exercise. Studies investigating the use of background music on enhancing endurance performance demonstrate that music not only influences performance but is effective in lowering RPE (11-13). Other studies that have investigated effects of different kinds of

2

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

music on physiological and psychological parameters during aerobic exercise also demonstrate that music is effective in lowering heart rate, blood pressure, and circulating hormones in addition to lowering RPE (49, 50). However, these studies compared different types of music that were pre-selected by the investigator. Other studies that have used PM or self selected music during exercise show lower RPE in comparison to different forms of visual distraction or sensory deprivation (37, 42). In these studies central, peripheral and overall RPE were examined during aerobic exercise. RPE was found to be lower with a music condition during cycling and treadmill exercise in comparison to combined visual and auditoiy stimulus conditions. Based on these findings, PM may also be more effective in lowering RPE and subsequently enhancing enjoyment during exercise than non-musical auditory stimuli like dialogue. In a study examining the effects of music on exercise adherence and cognition, researchers found that a 30 minute aerobic exercise program with self-selected music was more effective in improving cognition and exercise program adherence than an identical exercise program performed with casual conversation in patients with moderate to severe dementia (57). Although the study was conducted using a clinical population with psychological limitations, the study clearly demonstrates the efficacy o f a self-selected music condition over a non-music condition in promoting greater exercise program adherence. There are currently no studies which show that a PM condition will produce a lower RPE during exercise than an AB condition at the same exercise intensity and duration.

3

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Purpose The purpose of the study was to determine if two different forms of auditory stimuli will exhibit differential effects on RPE during continuous bouts of aerobic exercise. Primary Aims: 1. To compare the differential effects of PM and AB listening conditions on RPE during 20 minutes of submaximal treadmill running in an apparently healthy population. 2. To examine the differences between enjoyment ratings after exercise under the PM and AB conditions

Secondary Aim: 1. To examine the differences between select metabolic variables collected during exercise under the PM and AB listening conditions. Hypotheses: Primary Hypotheses: 1. It was hypothesized that exercising with a PM condition will produce a significantly lower RPE in comparison to an AB condition at the same exercise work load. 2. It was hypothesized that higher enjoyment ratings of exercise will be positively associated with a lower RPE. Secondary Hypotheses: 1. It was hypothesized that metabolic variables collected during exercise under the PM condition will be significantly lower than the AB condition at the same work load.

4

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

2. It was hypothesized that a lower metabolic rate during exercise with the PM condition will reflect a lower RPE during exercise with the PM condition.

5

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

II. LITERATURE REVIEW

A substantial portion of the American population is highly sedentary (1). There are a variety of negative health implications associated with physical inactivity including the development of chronic diseases such as diabetes, hypertension, hyperinsulinemia, hyperlipidemia, heart disease and obesity. According to a position stand published by the American College o f Sports Medicine in 2001, more than 55% of the adults over the age of 18 are classified as being overweight. O f these adults, 20-25% meet the criteria for obesity (BMI > 30) (23). It is also the position of the ACSM that a combination of dietary modification and exercise is the most effective approach for weight loss, with maintained commitment to exercise being the best predictor of long term weight loss. However, approximately 40% of Americans do not engage in physical activity regularly and find it challenging to commit to moderate amounts of recommended physical activity (i.e. 30 minutes of accumulated moderate intensity physical activity performed on most, and preferably all, days of the week) to improve health and prevent disease and disability (1). Identifying factors that maintain or improve regular commitment to exercise may prove useful in promoting long term adherence to exercise. One strategy would be to develop an understanding of what situational and dispositional factors have the greatest effect on attenuating perceptions of exertion during physical activity while maximizing the degree of enjoyment experienced. In this study, two auditory stimulus conditions, a

6

Reproduced with permission o f the copyright owner. Further reproduction prohibited without permission.

preferred music (PM) stimulus and a subject selected audio book (AB), were examined for their differential effects on ratings of perceived exertion (RPE), perceived enjoyment, and physiological responses during a continuous bout of aerobic exercise. It is important to analyze the distinctions between these two conditions and provide justification for their differential effects on physiological and perceptual aspects of human response and behavior in order to understand how they may be of use in modifying exercise adherence. This literature review is an account of theoretical perspectives and empirical research findings which address the question of whether different situational factors, specifically PM and AB stimulus conditions, can significantly effect the perception of exertion, enjoyment and physiological responses during exercise. The situational and dispositional factors which effect RPE during exercise are complex. The psychophysiological model of perceived exertion developed and modified by Noble et al. demonstrates that both psychological and physiological factors effect RPE during exercise. These factors may act in concert or independently of one another (38). While the physiological responses acting on RPE may be effected by quantifiable stimuli such as exercise intensity and duration, the psychological responses also acting on RPE during exercise are effected by stimuli which are definable but not always quantifiable. These factors include but are not limited to past exercise experience, level of motivation, personality, and attentional focus. Collectively they can be referred to as a reference filter o f psychological stimuli or stimulus components that affect RPE during exercise. In the current study, the physiological factors which impact RPE were set relative to each of the subjects (% of HR Max.) and held constant for the entire exercise duration (20 minutes). Then a single stimulus influencing the psychological reference filter, a PM and AB

7

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

stimulus, was manipulated to change the situational context in which the exercise was performed. Thus, any changes in RPE between two exercise sessions at the same work load could be attributable to the manipulation of variables that directly affect the psychological atmosphere in which the exercise is performed. In the current study, preferred and subject selected auditory stimuli were chosen to determine their impact on perceptual and metabolic responses by potentially influencing components of the psychological reference filter. Subjects were permitted to choose their music in this study rather than having the investigator provide the subjects with a pre-selected music stimulus. Because music is a highly subjective phenomenon and considerable variation exists in musical preference between individuals, it is important to consider how individual variations in preference will effect the enjoyment of exercise, and perhaps more importantly, how they effect long term adherence to physical activity. We know that perception and reaction to sound and physical contact are indispensable components of the initial stages of learning as well as throughout the lifespan (14). The development of these sensory perceptions allows humans to cultivate and focus their willful curiosity to seek knowledge, formulate opinions, and make sense o f the external environment. Play, activity, physical interaction and music, or individual sounds, are initially diffuse and vague stimuli which are categorically indistinguishable and yield no source of meaning to which one can identify or associate oneself. Subtle differentiations in sound exposure are gradually internalized over time as personal significance is applied to them (19). The developmental theory evaluating learning and meaningful recognition of sensory stimuli postulated by Werner, advocates the process of stimulus differentiation and integration as a continuum subject to change, reinforcement,

8

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

regression and evolution as we continue to grow and age (19). This process becomes more apparent with the progressive shift in preference towards certain types of music and physical activity as we age. Examining music as a supplement to verbal communication, fundamental similarities can be drawn between music and spoken language in that they are both constructed from their respective rudimentary systems and rules. Music and spoken language are the products of sound organization in time. Music and language, when put in a cultural context, either include or exclude the arrangement of specific sounds which classify them as music or spoken language. In the same way language is quantified by the number of syllables in a sentence, music is also enumerated by the number o f beats in a particular measure. A number of meaningful parallels may be extracted from both music and language for further division into superficial and deep structures as evident in the work of Sloboda (46). The pitch, inflection, and tonality of a particular piece of music may share its equivalent in the form of spoken language depending upon its delivery, syntax and phonology. One distinguishing characteristic which defines music in a way that is not typically reproduced in verbal communication is the complexity of its physical constructs and its representation as a spatial body of sound. Varese, in his investigation of timbre, acoustic percussion, and pitch, came to regard music as a spatial construct of sound which rotates much like a physical object in space (58). From this perspective, there is a greater inclination to relate to music physically where it would prove difficult to do so with verbal language alone. Evidence for this statement can be found in studies by Brownley et al. and Copeland et al., both concluding that musical tempo and rhythmic

9

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

structure have measurable effects on endurance running performance (7, 11). In summary, music represents or conveys movement in time and the perception of this construct facilitates physical movement in response in a manner that is independent of the perception accompanied by language recognition. These differences between music and dialogue may be significant when considering their differential impacts on the situational context in which exercise is performed and the psychological reference filter effecting RPE. It is certain that both physiological and psychological factors influence RPE. However, the interaction o f different auditory stimuli with psychological variables, such as personality and mood state, may positively or negatively impact RPE and enjoyment when physiological factors such as intensity and duration are held at a constant. One of the major problems associated with the decline in physical and mental health in the United States is inactivity. Despite the well published benefits of regular exercise for preventing chronic disease, the majority of Americans remain inactive. One explanation for this phenomenon is that the degree of physical discomfort experienced may suppress any drive for completing the intended duration or intensity of exercise (13). Without an external source of distraction, the amount of discomfort could be magnified as physical stress becomes greater with continuous exercise (2, 3). Another possible explanation is that structured exercise using traditional modalities (i.e. treadmill running) may prove to be more exhausting than satisfying, enjoyable, and restorative (13). Due to the relatively prosaic, linear, and repetitive nature, traditional exercise modalities may not foster the level of psychological engagement necessary to stimulate further interest in completing the exercise (26). Research by Boutelle et al. shows that the use of music in increasing the attractiveness of a stairwell in a school of public health promoted greater

10

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

usage o f the stairs within the facility by faculty and students (5). This study demonstrates that by improving the aesthetic qualities of a rather laborious and repetitive task like stair climbing, a greater commitment was made to stair usage among a population considered to be health conscious and who should have otherwise chosen to use the stairs because they were aware o f health benefits and the negative implications of inactivity, not because of its aesthetic quality. Results from research studies conducted in the field of ergonomics on efficiency performance during repetitive work tasks in industrial settings lends strong support to the contention that even background music aids in work efficiency, and productivity. A study by Fox and Embry showed music was effective in raising efficiency when used to compete with unfavorable noises produced by factory machines (17). A similar application of background music in an environment where physically repetitive tasks are being performed and unfavorable noises are produced by machines is a modem gymnasium. Priest et al. investigated the use of different types of music in gymnasiums and found that music influenced the frequency and consistency of gym attendance (43). Priest et al. concluded that the musical idiom, rhythmic structure, and genre specification should be taken into consideration when accounting for the preferences of different individuals attending the gym throughout the day. A study by Hayakawa et al. demonstrates the use of music during a repetitive bench stepping exercise generated fewer reports of fatigue than bench stepping performed without music among apparently healthy test subjects (21). The familiarity of the music stimulus, defined by the frequency of exposure to certain songs, plays a significant role in improving both physical endurance performance and cognitive vigilance during repetitive tasks as evident in

11

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

research by Crust and Fontaine et al. (12,16). Music has also been shown to be useful as an attentional distraction technique to increase the adoption of regular exercise behaviors among sedentary and obese populations. A study by DeBourdeaudhuij et al. demonstrates that music’s effects as an attentional distracter during incremental treadmill running tests in severely obese adolescents significantly improved treadmill running time and subject perseverance (13). Sedentary behavior is a highly refractory problem deeply rooted in the interactions between the individual and his/her environment. Causality behind any individual’s propensity for physical inactivity can not be directly inferred by the lack of distraction or favorable stimulus during exercise. However, subjective ratings of discomfort and exertion under varying conditions during exercise can provide a key insight to modifying an exercise so the experience is enjoyable. The perception of physical exertion during exercise stems from the cognitive processing of information from physical stress sources such as muscular fatigue and breathlessness as a result of increased work, and from external sensory signals derived from the exercise environment such as temperature, humidity, visual, and auditory stimulus (7, 37). Subjective ratings of exertion are highly reflective of the changes in physiological parameters such as heart rate and oxygen consumption with varying exercise intensities (38). The Borg ratings of perceived exertion (RPE) 15-point scale, one commonly used index for measuring subjective ratings of exertion and highly validated in previous research, is positively related to the amount of active muscle mass and the actual metabolic demand associated with a particular physical task (34). The primary outcome variable assessed in the current study was RPE using a 10-point omnibus (OMNI) scale which serves as an amalgamous

12

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

rating o f sensory perception encompassing both affective and somatic divisions of sensation. The OMNI scale has been validated as an accurate means of establishing perceived exertion during exercise (56). Although subjective estimates of physical work and its relationship to physiology are well established, a significant portion of the variability in subjective perception of work can by accounted for by factors such as mood state, personality and other components of the psychological reference filter (10, 33, 38). In a study investigating various psychological factors influencing perceived exertion, Morgan found that extroverts tend to underrate the perceived intensity o f exercise at higher work loads and their work load preferences tend to be higher for prolonged exercise than it is for introverts. The interaction of music and personality characteristics may also play a profound role in enhancing performance and in altering the perception of difficulty for a given task. In a study by Fumham and Strbac comparing performance on cognitive tasks between introverts and extroverts exposed to background music, extroverts showed significantly greater performance and introverts were more negatively affected by musical distraction (18). Although this example pertains to cognitive performance tasks, it should be noted that physical performance during exercise is not entirely independent of cognition. The level of cognitive engagement towards a given exercise task is highly reflective of the duration and intensity at which the task is being performed (34). For individuals that do not find satisfaction by engaging in some form of physical activity but find satisfaction through their relationship with music, perhaps a stronger internal association between exercise and music by changing the psychological context in which the exercise is performed can generate intrinsic motives for increasing the

13

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

commitment to daily physical activity. The ability of the exerciser to manipulate the physiological components of exercise with psychological interventions that render it a positive experience may have some significant implications for more long term dedication to structured exercise programs (39, 40). Varying the type of psychological sensory information available to the exerciser may influence their perception of exercise intensity by the dissociation of physical stress cues from the psychological perception of exertion and discomfort (50). The utility of music in modifying physiological and psychological responsiveness to cognitive and physically demanding tasks has been examined in variety of experimental scenarios among populations of varying demographics (8, 9,15, 21). Among the studies conducted on clinical populations suffering either cardiac or pulmonary complications, using a music intervention during exercise rehabilitation programs has been shown to produce a significantly lower RPE in comparison to programs without music(2, 35, 51). In studies that reported no significant difference in RPE, ratings of mood and affect were positively influenced by a music intervention during exercise suggesting exercise was more enjoyable with music, a characteristic that is essential for maintaining exercise program adherence during rehabilitation (6, 40). Van de Winckel et al. found that a 30 minute aerobic exercise program with a self-selected music intervention was more effective in improving cognition than an identical exercise program performed with casual conversation in patients with moderate to severe dementia (57). Although no current literature supports the application of music over verbal dialogue in an apparently healthy population, it is important to mention the beneficial use o f music during exercise in clinical populations with psychological

14

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

limitations such as dementia. This finding signifies that music maybe useful in promoting exercise adherence by increasing enjoyment at a lower RPE. A number of other studies demonstrate that healthy, physically active individuals who perform aerobic exercise at moderate to high intensities while listening to music produce significantly lower RPE in comparison to conditions with identical workloads without music or with sensory deprivation (11, 12, 49, 50, 63). In addition, previous research investigating the influence o f situational context on RPE during prolonged exercise using different types of visual, musical stimulus and sensory-deprivation conditions have also demonstrated that RPE is significantly lower during exercise with a music stimulus (4, 37, 50). In studies by Potteiger et al. and White et al., central, peripheral and overall RPE were lower with a music intervention during cycling and treadmill exercise in comparison to combined visual and auditory stimulus interventions. Although there is no evidence advocating the use of preferred music over a dialogue recording to produce a lower exercising RPE, these findings provide support for the hypothesis that preferred music may be more effective in altering the perception of effort than other forms of sensory distraction or deprivation. Possible mechanisms for a lower RPE during exercise with music include decreased sensitization of the endocrine stress response systems with specific regard to the hypothalamic-pituitary-adrenal axis. Khalfa et al. reported that the concentration of salivary cortisol decreased rapidly in subjects exposed to music after acute stress and in those exposed to silence salivary cortisol levels continued to rise (27). Research by Szmedra et al. demonstrates higher values for hemodynamic variables (heart rate, systolic blood pressure) and lactate with no music during exercise at workloads relative to each

15

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

subjects aerobic capacity (percentage of VChmax). The researcher concluded that all exercise conditions using music allowed subjects to reduce muscle tension thereby increasing blood flow and lactate clearance. This increased clearance effected heart rate and breathing frequency causing a 10% decrease in RPE among subjects exercising with music. Levels of norephinephrine were also lower indicating a decreas e in the sympathetic division o f the autonomic stress response (50). A recent review by Salamon et al. stated that nitric oxide, an essential molecular compound for inducing vasodilation to increase blood flow, has been determined to aid in the development of the auditory system and is a significant contributor in increasing cochlear blood tl ow. This theoretical model suggests that music induced relaxation may be mediated by t h ; same mechanisms that develop auditory sensitivity to music (45). The precise physiological mechanisms which alter the perception of physical work while listening to music are still not fully understood (45, 50). Findings from Szmedra et al. Salamon et al., and Khalfa et al, introduce scientific .justification that music can significantly alter physiology. However, no evidence is provided to indicate what musical qualities generate physiological responses during periods of physical stress. If these responses only occur due to a cognitive recognition of an z uditory stimulus, than it may also hold true that any auditory stimulus can cause the dissociation of physical stress from the perception o f stress. If there is an affective compo lent which proceeds the cognitive recognition of an auditory stimulus being present then \ erhaps preferred music may show a different effect on RPE during exercise than an a dig iogue recording. Evoking the emotional, personality, or motivational component; .ssociated with musical recognition may contribute significantly to altering perception o f effort during exercise

16

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

where another auditory stimulus such as a recorded dialogue may not. This is perhaps adequate justification for the assumption that preferred music will generate a lower RPE during exercise than another auditory stimulus in comparison. Therefore, PM and AB auditory stimuli may have differential impacts on the psychological reference filter effecting RPE. The purpose of the study was to determine if two different forms of auditory stimuli will exhibit differential effects on RPE during continuous bouts of aerobic exercise.

17

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

III. METHODS

Subjects 20 students (10 male, 10 female) were recruited for this study from the University of Louisville campus and the greater Louisville, Kentucky area. Subjects were recruited on a volunteer basis without compensation. The subject sample was comprised of apparently healthy, as defined by ACSM criteria, undergraduate/graduate students who had no contraindications for moderate intensity exercise. The basis for this subject categorization is outlined by the inclusion and exclusion criteria. The majority of the subjects were exercise science majors and all reported regular participation in a health/fitness exercise program (i.e. aerobic training 2-3 days per week for 20-60 minutes per session). Inclusion and exclusion criteria are listed below.

Inclusion Criteria 1. Subjects between 18 to 30 years of age. 2. Subjects who reported regular participation in a health/fitness exercise program (i.e. aerobic training 2-3 days per week for 20-60 minutes per session) and had prior experience running on a treadmill within the past 6 months. 3. Subjects were free o f medical, physical or cognitive impairment that could limit or compromise participation in testing or otherwise prevent the volunteer from giving informed consent. 4.

Subjects, were w illing to give informed consent to participate in this study, agreed

to randomization, agreed to the demands of the study, and were able to attend both randomized testing sessions. 5. Subjects were not pregnant. 6. Subjects had no additional contraindications for participating in 20 minutes of sustained submaximal aerobic exercise involving major muscle groups of the upper and lower body.

18

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Exclusion Criteria 1. Individuals wl o failed to meet the inclusion criteria. 2. Individuals w: th acute or chronic injuries such as musculoskeletal and orthopedic problems whi ;h may have prevented the subject from engaging in 20 minutes of sustained run; ling. 3. Individuals \v ho had minor or significant hearing loss or congenital disability. 4. Individuals with medical history of exercise induced asthma or who were currently astlimatic. Upon meeting the necessary criteria and agreeing to participate, subjects were briefed about the purpose of the study. All subjects gave their written informed consent. The procedures era ployed during testing were described in the informed consent document and had received prior approval through the Human Studies Committees and Institutional Review Board of the University of Louisville.

Procedure The exerc ise protocol was structured to reflect a counterbalanced randomized study design. Testing was divided into two sessions based upon the order in which the subject was randomized to either a preferred music (PM) or a subject selected audio book (AB) condition. Assignment to the remaining test condition was contingent upon successful com pletion of the first session. All test ing was conducted at the University of Louisville Exercise Physiology Laboratory located in Crawford Gym on the Belknap Campus. Subjects were instructed to avoid eating and caffeine 4 hours before testing, and to avoid vigorous exercise within 24 hours o f testing to avoid any confounding influences of exercise on the subject’s level of fatigue. S i ejects were also instructed to wear comfortable clothing and shoes for running. Gc r eral demographic information including height, weight, age, gender, and 75%-85%' i ;art rate range based upon age predicted maximum HR (APMHR), were

19

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

acquired prior to exercise. Subjects were fitted with a HR monitor, oriented to the treadmill adjustment controls, and instructed to warm up by either walking or running on the treadmill for 2-3 minutes. During this time, subjects were instructed to select a speed they perceived as comfortable or tolerable for completing a 20 minute run. The speed was approved by the researcher if the subjects HR reached 75%-85% of APMHR. This speed remained constant throughout the duration of the test. Subjects then dismounted the treadmill, and were fitted with head gear, mouthpiece connected to the metabolic analyzer, and the personal audio headset set to the appropriate decibel range. Data collection for each session was approximately 28 minutes in duration. Data collection was partitioned into 4 minutes of treadmill walking at a speed of 3.0 mph without the auditory stimulus intervention to collect baseline metabolic rates prior to running, 20 minutes of running at a subject selected speed with the auditory stimulus intervention, and 4 minutes of walking at a speed of 3.0 mph without the auditory stimulus condition to collect metabolic data during recovery. The personal head set was activated immediately after the initial 4 minute walk. RPE was assessed every 5 minutes (within the last 15 seconds of the fifth minute) and HR was recorded every minute (within the last 15 seconds of every minute) during the 20 minute run. Immediately following data collection, the mouthpiece, head gear, personal audio headset, and HR monitor were removed. The subject was then instructed to rate perceived enjoyment by assigning a number to the modified 10 point Likert scale that best corresponded with their degree of enjoyment. This same testing procedure was replicated on a non-consecutive day with the same running and walking speeds with the other intervention the subject had not been previously randomized to.

20

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Measures Psychological Assessment of Physical Work: Omnibus ratings of perceived exertion (OMNI RPE) (see Appendix A), a subjective scale of effort (44), was used as an index for measuring general overall perceptions of exertion during exercise under both experimental conditions, preferred music (PM) and dialogue recording from a subject selected audio book (AB). RPE is a highly validated and accurate method of assessing psychosomatic perception and sensitivity based upon the degree of corresponding physiological actuation and stimulation. Standardized anchor points were used to establish the high and low ends of the exertion scale to help subjects utilize the lull range of the scale numbers and provide accurate estimations of physical exertion at different stages of the exercise protocol. Anchor points were individualized to each subject using a memory procedure. Subjects were read a set of instructions taken from the anchoring procedures described in the RPE manual by Robertson entitled “Perceived Exertion for Practitioners”, which asked them to recall a time when their level of exertion was at its highest and assign a rating of 10 to the sensation of exertion which closely resembled that previous experience. Subjects were also instructed to recall an instance when their level o f exertion was at its lowest and assign a rating of 0 to the sensation which resembled that experience. Auditory Stimulus Intervention: Both PM and AB samples were pre-selected by the subject prior to exercise. Dialogue recordings were chosen from a compiled database of books on CD encompassing multiple genres of literary works (fiction in the form of mysteries, and science fiction novels, nonfiction, and biographies), symposia and educational compilations. Each subject supplied their own music. A limited number of

21

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

constraints were placed upon the subjects’ musical preferences. Subjects were permitted their preferred selections providing they were songs which contained a vocal element and a tempo between 80-100 bpm. Bpm was determined using Adobe Audition 1.5 music editing software (Adobe Systems Inc.). All music was digitally transferred to an electronic database and a number of songs equivalent to 20 minutes in duration were selected and arranged in a preferred order by the subject. PM and AB samples were administered with a personal electronic headset (Ipod Shuffle, electronic mp3 player, Apple Inc.) in an attempt to limit external noise and other distractions during exercise. Both PM and AB selections shared similar decibel characteristics. The volume level on the personal headset was adjusted by the investigator prior to exercise to match a decibel level between the ranges o f 60-70 for both conditions using a digital sound meter (DSM 100, Universal Enterprises Inc., Beaverton, OR). Enjoyment Rating: To establish a subjective rating of enjoyment for both PM and AB testing conditions a modified 10 point Likert Scale was implemented after the exercise bout (see Appendix B). Developed by Rensis Likert, the Likert Scale is a psychometric measurement used for determining the strength of agreement or for gauging attitudes or reactions to a particular question, statement, or stimulus (62). Subjects were instructed to rate their enjoyment of both PM or AB stimuli individually and to avoid biasing their enjoyment rating by comparing the two conditions. The scale was anchored by two polarized definitions of enjoyment. A rating of 0 was assigned if the PM or AB was not enjoyable at all, and conversely, a rating of 10 was assigned if the PM or AB was very enjoyable. Subjects were then instructed to rate enjoyment along the scale accordingly. Ratings o f enjoyment were collected following active recovery.

22

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Physiological Assessment: Metabolic and hemodynamic variables were monitored continuously during exercise as the primary means of objectively assessing physiological responses to physical work. Heart Rate (HR) was measured using a chest strap monitor interfaced with the Trotter treadmill display (Polar Electro Inc., Lake Success, NY). HR responses were recorded at the last 15 seconds of every minute during exercise. Metabolic and respiratory variables were captured through the use of open circuit spirometiy with a standard metabolic analyzer (TrueMax 2400, ParvoMedics, Sandy, UT). These variables included total caloric expenditure (KCAL), metabolic task equivalent (METS), total oxygen consumption (VO2 ), respiratory frequency (/) total ventilation (VE), and tidal volume (Vt). Samples of expired gases were averaged and recorded every 30 seconds during exercise.

Statistical Analysis The principle outcome measure was RPE using a 10 point OMNI scale. Other secondary outcome measures analyzed included heart rate (HR), total caloric expenditure (KCAL), peak metabolic task equivalency (METS), total oxygen consumption (VO2 ), respiratory frequency (/), tidal volume (VT), total ventilation (VE) and auditory stimulus enjoyment ratings. All analyses were performed using the Statistical Packages for the Social Sciences software (SPSS Version 14.0). A paired samples t-test was used to examine differences for RPE and all secondary outcome measures between the PM and SSDR interventions. All analyses were conducted at an alpha level o f p < 0.05. Power Analysis: Power analyses were conducted to determine the number of subjects needed to find significant differences in RPE (OMNI scale) after submaximal

23

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

exercise with an auditory intervention. Research examining the effects of music on a wide array o f physiological and psychological variables during submaximal treadmill running conducted by Szmedra et al. revealed that the average RPE for exercise with music was (12.9 ± 0.41) when compared to exercise without music (14.4 ± 4.3). Power calculations (UCLA Department of Statistics Power Calculator, Los Angeles, CA) based upon these findings show that a minimum of 30 subjects would be needed to determine a difference in RPE between music and non-music conditions. Other research by Potteiger et al. examining the effects of fast, classical, and self-selected music on RPE during 20 minute submaximal exercise bouts produced significantly lower RPE with the three music conditions than the no music condition in healthy subjects aged 18-30. Power calculations based upon the results from the self-selected music and no music groups (14.4+0.3 vs. 15.2+0.3) demonstrates that a minimum of 6 subjects would be needed to determine a difference in RPE between music and non-music conditions in subjects performing submaximal treadmill running. Research by Brownley et al. examining the effects of music on graded treadmill running in trained and untrained revealed that RPE was lowest in the healthy untrained subjects while listening to music (15.9+0.7 vs. 16.6+0.6). Power calculations based upon these results indicate that a sample size of 11 would be sufficient to determine a difference in RPE between music and non-music conditions. Based upon these findings, a recruitment total of 20 subjects were deemed necessary to detect a moderate effect and a power of 0.80.

24

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

IV. RESULTS

This study examined two distinct types of auditory stimuli and their differential effects on ratings o f perceived exertion (RPE) during submaximal running bouts. RPE using a (0-10) point OMNI scale was collected during 20 minutes of continuous submaximal running under two experimental conditions, preferred music (PM) and a dialogue recording using a subject selected audio book (AB). Metabolic variables were also collected. An equal number of male and female subjects were recruited for the study. There were a total o f 17 Caucasians, 2 Hispanics, and 1 African-American (males = 10, females = 10). The mean age o f the participants was 23.4 ± 2.4 with an average body mass index of 22.84 ± 3.0 (mean height in cm 174.8 ± 8.2, mean weight in kg 70.56 ± 11.6). There were no significant differences between genders for any of the primary or secondary outcome variables. Therefore, data for males and females was combined for all analyses. Ratings of Perceived Exertion and Enjoyment: RPE was collected at five minute intervals during each 20 minute running bout and averaged over the session. Peak RPE for the session was also averaged. Figure 1 provides a summary of means, and standard deviations for both conditions at 5 minute collection intervals. Data were analyzed to determine significant differences between PM and AB conditions. Data analyses revealed significantly higher mean RPE scores for the AB condition (4.30 ±

25

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

0.83) than the PM condition (3.65 ± 0.87),p < 0.05. In addition, peak RPE scores for the AB condition (5.40 ± 1.23) were also significantly higher than the PM condition (4.30 ± 0.98),/? < 0.05. When data were examined to explore differences in perceived enjoyment between PM and AB conditions, results indicate that mean scores of enjoyment were significantly greater for PM condition (8.95 ± 0.95) than the AB condition (5.60 ± 1.64), p < 0.05. A summary o f means, and standard deviations for enjoyment data is provided in

Figure 2. In summary, the results show greater enjoyment ratings and lower RPE for the PM condition. Metabolic Cost and Energy Expenditure: Values for oxygen consumption (VO2 ), total energy expenditure (KCALS), and metabolic equivalency (METS) were collected at 30 second intervals for the duration of exercise and during the active recovery period post-exercise. Data were analyzed to determine significant differences between PM and AB conditions for V 0 2, METS, and KCALS. Means, standard deviations, paired statistical differences and significance for average, peak, and post­ exercise V 0 2, peak METS and total session KCALS are summarized in Table 1. VO2 : Data analyses revealed significantly higher average VO 2 for the PM

condition (34.89 ± 4.12) than the AB condition (34.11 ± 3.57),p < 0.05. In addition, peak VO 2 was also significantly higher for PM (38.51 ± 4.48) than the AB condition (37.33 ± 3.85),/? < 0.05. However, post-exercise VO 2 was not significantly greater for the PM condition (19.01 ± 2.71) compared to the AB condition (18.71 ± 2.09), p < 0.05. METS & KCALS : When data were examined for differences in peak METS and

total KCALS between PM and AB conditions, results indicate peak METS were significantly higher for the PM condition (11.01 ± 1.28) than the AB condition (10.67 ±

26

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

1.12) and total KCALS were significantly greater for the PM condition (292.60 ± 57.74) when compared with the AB condition (285.15 ± 54.31), P < 0.05. These results demonstrate that metabolic cost and energy expenditure were higher for the PM condition than the AB condition at the same exercise workload. Respiration: Values for ventilation (VE), respiratory frequency (/), and tidal volume (VT) were collected at 30 second intervals for the duration of exercise and during the active recovery period post-exercise. Data were analyzed to determine significant differences between PM and AB conditions for VE, / and Vt. Means, standard deviations, paired statistical differences and significance for average, peak, and post­ exercise VE, / and VT are summarized in Table 1. VE\ Data analyses revealed significantly higher average VE for the PM condition

(55.42 ± 11.51) than the AB condition (52.71 ± 10.86),/? < 0.05. In addition, peak VE was significantly higher for the PM condition (63.77 ± 14.29) than the AB condition (59.86 ± 12.77),/? < 0.05. However, post-exercise VE was not significantly higher for the PM condition (32.77 ± 7.76) compared to the AB condition (31.42 ± 7.23),/? < 0.05. / : When data were examined for differences in f between PM and AB conditions, results indicate average/ was significantly higher for the PM condition (37.33 ± 6.42) than the AB condition (34.81 ± 5.37),/? < 0.05. In addition, peak/ was significantly higher for the PM condition (44.45 ± 7.03) than the AB condition (41.90 ± 7.23), as well as post-exercise/ which was also significantly higher for the PM condition (29.85 ± 7.82) compared to the AB condition (28.35 ± 7.65),/? < 0.05. Vf. When data were examined for differences in V t between PM and AB

conditions, results indicate average V t was not significantly higher for the PM condition

27

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

(1.51

± 0 .3 1 ) than the AB condition (1 .5 2 ± 0 .3 2 ),;? < 0.05. In addition, peak Vt was also

not significantly higher for the PM condition (1 .4 5 (1 .4 4 ± 0 .2 6 ),/? < 0 .0 5 .

0.29)

compared to the AB condition

However, post-exercise V j vas significantly lower for the PM

condition (1 .1 2 ± 0 .2 5 ) compared to the AB condi i on (1.52 ± 0 .3 2 ),/? < 0 .0 5 . These results demonstrate that both V e and/ were higher during exercise with the PM condition. However, VT was not higher during exercise with he PM condition and was lower during active recovery with the PM condition. Heart Rate: HR was collected every minute during exercise. Data were analyzed to determine significant differences between PM and AB conditions for HR. Means, standard deviations, paired statistical differences and significance for average, and peak heart rate (HR) are summarized in Table 1 . Data analyses revealed significantly higher average HR for the PM condition (1 6 8 .1 4 ± 14.S 4 ) than the AB condition (1 6 2 .7 0 ± 1 3 .9 2 ),/? < 0 .0 5 .

In addition, peak HR was also significantly higher for the PM condition

(1 7 5 .6 5 ± 15.84)

compared to the AB condition (1 7 0 .9 5 ± 14.26),/? < 0 .0 5 . These results

demonstrate that HR was higher for the PM cc i dition in comparison to the AB condition.

28

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Table 2. Effects of Auditory Condition: Means by Condition. Paired Samples T-Test

Variable

PM

AB

Paired Differences

VO 2 : Average (ml/kg/min) V 0 2: Peak (ml/kg/min) V 0 2: PostExercise (ml/kg/min) KCALS: Total METS: Peak Respiration V e: Average (L/min) V e: Peak (L/min) V e: PostExercise (L/min) f. Average (bpm) f: Peak (bpm) f. Post-Exercise (bpm) V t: Average (L) VT: Peak (L) Vy: PostExercise (L) Heart Rate: Average (bpm) Peak (bpm)

34.89 ±4.12

34.11 ±3.57

0.78 n: 1.44

0.03*

38.51 ±4.48

37.33 ±3.85

1.19 ± 1.86

0.01*

19.01 ±2.71

18.71 ±2.09

0.30 ± 1.57

0.40

292.60 ± 57.74 11.01 ± 1.28

285.15 ±54.31 10.67 ± 1.12

7.45 ± 12.64 0.35 ± 0.53

0.02* 0.01*

55.42 ± 11.51

52.71 ±10.86

2.71 ±3.04

0.01*

63.77 ± 14.29

59.86 ± 12.77

3.91 ±3.71

0.01*

32.77 ± 7.76

31.42 ±7.23

1.35 ±3.99

0.15

37.33 ± 6.42

34.81 ±5.37

2.13 ±2.69

0.02*

44.45 ± 7.03 29.85 ± 7,82

41.90 ±7.23 28.35 ± 7.65

2.55 ±3.41 1.50 ±3.20

0.03* 0.04*

1.51 ±0.31

1.52 ±0.32

-0.02 ± 0.09

0.40

1.45 ±0.29 1.12 ±0.25

1.44 ±0.26 1.52 ±0.32

0.01 ± 0.09 -0.40 ±0.19

0.75 0.01*

162.70 ± 13.92 170.95 ± 14.26

5.44 ± 3.68 4.70 ±4.28

0.01* 0.01*

Sis. (2-tailed)

• 168.14 14.94 175.65 ± 15.84

* Significant at p < 0.05 Oxygen consumption (V02), caloric expenditure (KCAL), metabolic equivalency (METS), total ventilation (VE), respiratory rate (RR), tidal volume (VT), heart rate (HR)

29

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Figure 1. Mean RPE Scores by Condition for Five-Minute Measurement Periods

30

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Figure 2. Mean Enjoyment Ratings by Condition

Enjoyment 12

31

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

V. DISCUSSION

The current study determined the effects of two different forms of auditory stimuli on ratings o f perceived exertion (RPE) during continuous bouts of aerobic exercise by using preferred music (PM) and subject-selected audio book (AB) stimulus conditions at the same exercise workload. Secondary outcomes such as perceived enjoyment, heart rate (HR), total caloric expenditure (KCAL), peak metabolic task equivalency (METS), total oxygen consumption (VO 2 ), respiratory frequency (f), tidal volume (Vt), and total ventilation (V e) were assessed to examine the physiological responses between the two different auditory stimuli. In this chapter the key findings of the study will be discussed. The results of the current study confirm the primary research hypotheses. The PM condition produced a significantly lower RPE in comparison to an AB condition at the same exercise workload. In addition, perceived enjoyment ratings were higher with the PM condition. However, the secondary research hypotheses were rejected. Metabolic variables collected during exercise under the PM condition were not significantly lower than the AB condition at the same work load. Metabolic rates during exercise with the PM condition were found to be significantly higher in contrast to a lower RPE for the PM condition. RPE and Enjoyment: It was hypothesized that exercising with a PM condition would produce a significantly lower RPE in comparison to the same exercise performed

32

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

with an AB condition. This hypothesis was supported by studies which demonstrate that exercising with music produced lower RPE in comparison with other non-musical stimulus interventions (4, 37, 4 2 , 5 0 , 6 3 ). Using different types of visual, musical stimulus and sensory-deprivation conditions, previous studies have investigated the influence o f situational context on RPE during prolonged exercise to also find that RPE was significantly lower during exercise with a music stimulus in comparison. A study by White et al. demonstrates that overall RPE was significantly lower with a music stimulus condition during cycling exercise in comparison with visual stimulus conditions (6 3 ). White et al. concluded that passive and dissociative stimuli exert a psychological influence on physiological events altering RPE. Nethery also found that cycling exercise performed at high (80% of V02max) and low (50% of VC>2max) workloads with video, sensory deprived, and control conditions produced significantly higher RPE than cycling performed at these same workloads with a music condition. The assertion put forth by Nethery is that in experimental scenarios where music is being compared to other sensory stimuli during exercise, RPE tends to be lower for stimulus conditions which direct attention and focus from sensations related to physical work during exercise (3 7 ). In the current study, the use of a PM stimulus, a situational factor of strong subjective preference, produced a lower RPE during exercise than another auditory stimulus, the AB condition, with perhaps a lesser value in terms of subjective preference. This result further substantiates Nethery’s assertion. The findings of the current study suggest that the PM stimulus may have had a more profound effect upon attentional focus and sensory awareness related to physical work thus exhibiting the greatest effect on RPE.

33

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

A unique characteristic of the current study was the use of two different types of subject selected auditory stimuli. One music condition, and one non-music condition, both o f which contained a vocal element. Because preference is highly subjective, this aspect o f the study design may have contributed to the amount of interaction between the auditory stimuli and psychological variables such as mood state and personality which impact the psychological reference filter effecting RPE (38). A study by Morgan investigating various psychological fact >rs influencing RPE, demonstrates that extroverts tend to underrate the perceived intensii' of exercise at higher work loads and their work load preferences tend to be higher for prolonged exercise than that of introverted personality types (34). The degree o f the interaction between PM and psychological variables such as mood state and personality, which are part of the psychological reference filter, may offer a potential e eplanation for why, in the current study, RPE was lower for the PM condition than the A 3 condition. Based upon these results, it can be assumed that the interaction between PM and other psychological factors occurred to a greater degree than with the AB, thus having a greater impact upon RPE. Physiological factors such as exercise intensity and duration which impact fatigue also play a role in how RPE is effect