Behavioral Medicine The Effects of a Peer Modeling Intervention on ...

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The Effects of a Peer Modeling Intervention on Cardiorespiratory Fitness Parameters and Self-Efficacy in Obese Adolescents a

Stefanie De Jesus & Harry Prapavessis

a

a

The University of Western Ontario Accepted author version posted online: 24 Jun 2013.Published online: 15 Nov 2013.

To cite this article: Stefanie De Jesus & Harry Prapavessis (2013) The Effects of a Peer Modeling Intervention on Cardiorespiratory Fitness Parameters and Self-Efficacy in Obese Adolescents, Behavioral Medicine, 39:4, 129-137, DOI: 10.1080/08964289.2013.813436 To link to this article: http://dx.doi.org/10.1080/08964289.2013.813436

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BEHAVIORAL MEDICINE, 39: 129–137, 2013 C Taylor & Francis Group, LLC Copyright ISSN: 0896-4289 print/1940-4026 online DOI: 10.1080/08964289.2013.813436

The Effects of a Peer Modeling Intervention on Cardiorespiratory Fitness Parameters and Self-Efficacy in Obese Adolescents Stefanie De Jesus and Harry Prapavessis Downloaded by [University of Western Ontario] at 05:49 18 November 2013

The University of Western Ontario

Inconsistencies exist in the assessment and interpretation of peak VO2 in the pediatric obese population, as cardiorespiratory fitness assessments are effort-dependent and psychological variables prevalent in this population must be addressed. This study examined the effect of a peer modeling intervention on cardiorespiratory fitness performance and task self-efficacy in obese youth completing a maximal treadmill test. Forty-nine obese (BMI ≥ 95th percentile for age and sex) youth were randomized to an experimental (received an intervention) or to a control group. The outcome variables were mean and variability cardiorespiratory fitness (peak VO2 , heart rate, duration, respiratory exchange ratio), rating of perceived exertion, and task self-efficacy scores. Irrespective of whether a mean or variability score was used, receiving the intervention was associated with non-significant trends in fitness parameters and task self-efficacy over time, favoring the experimental group. Cardiorespiratory fitness and task self-efficacy were moderately correlated at both time points. To elucidate the aforementioned findings, psychosocial factors affecting obese youth and opportunities to modify the peer modeling intervention should be considered. Addressing these factors has the potential to improve standard of care in a clinical setting regarding pretest patient education. Keywords: observational learning, obesity, adolescents, VO2 max, self-efficacy

There has been a dramatic increase in the prevalence of overweight and obese children in all regions of Canada.1 In fact, compared to other developed countries, Canada has one of the highest rates of childhood obesity.2 This is disconcerting because this preventable condition is strongly associated with the risk of future disease, such as adult obesity, insulin resistance, type 2 diabetes, obesity-associated sleep apnea, non-alcoholic fatty liver disease, cardiovascular problems, and psychosocial distress.3,4,5 This trend is a driving factor to develop effective and accurate strategies for physical activity and fitness assessment. Physical fitness refers to one’s physiological capability to execute daily activities with optimal performance, endurance, and strength, with the management of disease, fatigue, and stress, and reduced sedentary behavior.6,7 Physical fitness is a multidimensional set of attributes. Given the complexity, there are a variety of subjective and objective

Correspondence should be addressed to Stefanie De Jesus, Exercise and Health Psychology Laboratory, Room 408, Arthur and Sonia Labatt Health Science Building, London, Ontario, Canada N6A 5B9. E-mail: [email protected]

methods to characterize physical fitness, each differing in accuracy, reproducibility, and practicality for laboratory versus field-based testing. Cardiorespiratory fitness is the primary outcome assessed in the current study, and there are various approaches to assessing this parameter in the field and clinical setting. Maximal oxygen uptake (VO2 max ), or the leveling off of VO2 , is widely recognized as the criterion measure of cardiorespiratory fitness.8 Many individuals fail to elicit a plateau in VO2 ; thus, peak VO2 has been accepted as the highest VO2 observed during a maximal incremental exercise test and established as the parameter reported in research and used to generate physical activity interventions.9,10 Absolute VO2 , expressed in ml·kg−1·min−1, provides a measure of VO2 relative to the energetic costs of weight-bearing activities, such as walking and running. Maximal incremental exercise testing provides the most accurate measure of peak VO2 by evaluating the composition of expired respiratory gases as the workload progressively increases on a treadmill or cycle ergometer.11 Although it is accepted as the gold standard,12,13 maximal exercise testing requires infrastructure, trained technicians, and cooperative and motivated participants. Nevertheless, cardiorespiratory

Downloaded by [University of Western Ontario] at 05:49 18 November 2013

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DE JESUS AND PRAPAVESSIS

fitness testing is a surrogate measure of the functional status of the cardiovascular, pulmonary, muscular, and circulatory systems. Hence, considerable clinically diagnostic and prognostic knowledge, as well as exercise prescriptions, can be obtained from such a non-invasive tool.14 Although cardiorespiratory fitness testing yields a plethora of useful information to clinicians, exercise physiologists, and researchers, interpretation must be made with caution because assessments are effort-dependent. Adults have the capacity to process complex information, and hence understand the implications of a poor performance on maximal incremental exercise tests. On the other hand, children do not develop the ability to think and reason in abstract terms until mid adolescence.15 Consequently, youth have difficulties understanding the difference between exertion, ability, and difficulty of tasks as sources of achievement outcomes.16 Youth are also unlikely to be in pursuit of intangible benefits, such as health or fitness, and by extension, accurate peak VO2 values, especially at the expense of gratification.17 Eliminating such inconsistencies is necessary to interpret cardiorespiratory fitness data in an accurate and reliable manner, particularly during diagnoses and prognoses. Accuracy is the degree of veracity, or closeness of the data to its actual value. Poole and colleagues18 found an appreciable “under measurement” of VO2 max when a stringent respiratory exchange ratio criterion was implemented. Moreover, interpretation of pediatric aerobic fitness is fraught with psychological and physiological variability.19,20 With respect to psychological variability, researchers have neglected to find an effective and feasible manner to manipulate the psychosocial processes (ie, attitude, motivation, and competency) in children and adolescents in order to obtain peak VO2 values that are reflective of their true physical fitness capacity. Self-efficacy is a fundamental psychosocial construct of interest in health-related research21 that may play a key role in fostering maximal exertion by the pediatric population during vigorous tasks, such as cardiorespiratory fitness assessments. Self-efficacy is defined as “beliefs in one’s capabilities to organize and execute the courses of action required to produce given attainments.”22(p3) Self-efficacy has shown to be a determinant of the initiation, motivation, perseverance, and maintenance of behavior change.23,24,25 Vicarious experience, involving the process of learning from others through observation, is a major source of efficacious beliefs.21 It has been shown that observational learning is enhanced when there are positive reinforcing peer models involved.26 Peer models serve to increase self-efficacy if they are shown to overcome difficulties associated with the task with ease, the task is rewarding, and similarity between the model and the observer exists.27,28,29 Peer modeling has shown to be an effective tool in a wide range of populations for improving motor skill acquisition, altering psychological variables, and lifestyle behaviors.28,30,31 Directly relevant to the proposed study, Maddison et al32 evaluated the effectiveness of a peer modeling inter-

vention to increase peak VO2 and self-efficacy in people with chronic heart failure. Participants that observed the behavioral modeling DVD had higher peak VO2 and self-efficacy scores, compared to participants that received standard care (did not observe the DVD). The study conducted by Maddison and colleagues further suggests that this mode of learning could be employed to improve aerobic fitness values and bolster self-efficacy in apprehensive, obese youth, who typically do not put forth maximal exertion during aerobic fitness testing. To this end, the main objective of this study was to examine the effect of a peer modeling intervention on both mean and variability scores of cardiorespiratory fitness parameters and self-efficacy in obese youth completing a maximal treadmill test from baseline to follow-up, compared to an attention control group.

METHOD Participants Participants included 49 obese adolescents (26 male; M age = 12.65 years; M BMI = 32.36) recruited from London, Ontario. Participants were recruited from the Children’s Hospital at London Health Sciences Centre (LHSC) and through local pediatricians, newspaper advertisements, and electronic advertisements mailed to students at the University of Western Ontario and employees of LHSC. Individuals (N = 96) were initially screened, from which 47 individuals were excluded for not meeting inclusion criteria (N = 12), declined to participate (N = 29) and other reasons (N = 6). Inclusion criteria were: BMI greater than the 95th percentile for age and sex, 10 to 17 years of age, and completion of the Physical Activity Readiness Questionnaire. Participants, who smoked, were pregnant, or presented contraindications to exercise were excluded from the study. Intervention A peer modeling DVD (available upon request to the corresponding author) was developed by the authors and consisted of a male and female chapter, 4.8 and 6.35 minutes in length, respectively. Both chapters of the DVD were comprised of an edited interview and various action shots of an obese youth model performing a peak VO2 test. The DVD detailed the models’ psychological and physiological responses and expectations before, during, and after the cardiorespiratory fitness test. Models also demonstrated and verbalized increased confidence to perform the test (positive self-talk) and offered a variety of strategies to cope with the maximal effort and overcome the associated discomfort during the test (eg, shortness of breath, sweating, increased heart rate). Emphasis was placed on strategies the models used (attention control, breathing regulation, goals, and cue words) to focus their efforts during subsequent tests. Both chapters of the DVD were identical in content; however the female model

PEER MODELING AND OBESE YOUTH

was not as concise during the interview, accounting for the difference in duration (1.55 minutes) between chapters. An attention control DVD (5 minute duration) was developed prior to the start of the study. It consisted of a presentation by a medical student about healthy eating habits for children and adolescents.


Design and Procedure A stratified (age and sex) two-group randomized controlled trial was conducted with participants assigned to the experimental (peer modeling DVD) or control group (attention control DVD). Randomization was completed by a computergenerated randomized numbers table. Group allocation was concealed from participants and experimenters to reduce bias and contamination. This investigation received ethics approval from the University of Western Ontario Research Ethics Board (REB#16825) and was registered with Clinical Trials (NCT01382121). The conduct of the trial followed the principles outlined in the Declaration of Helsinki and the World Health Organization 2002 Good Clinical Research Practice. The conduct and reporting of the trial followed CONSORT principles. Participants attended two 1.5 hours sessions at the Exercise and Health Psychology Laboratory, one week apart (baseline and follow-up). Participants and parents provided informed consent before participating in the study. Participants completed demographic and self-efficacy questionnaires in addition to the Pediatric Quality of Life Inventory (PedsQofL)39 and the Physical Activity Questionnaire for Children (PAQ-C)40 at baseline. This was followed by the cardiorespiratory fitness test. Following the test, all participants completed the RPE scale. Those in the experimental group watched the peer modeling DVD. Male participants viewed the male peer model, whereas female participants viewed the female peer model. Participants in the attention control group watched the attention control DVD. After viewing their respective DVD, participants completed the manipulation, contamination, and motivation assessments. Seven days later (follow-up), participants returned and underwent identical procedures. Prior to the second cardiorespiratory fitness test, participants watched their respective DVD. All participants were asked not to change their physical activity patterns between baseline and follow-up visits. Measures

Cardiorespiratory Fitness Cardiorespiratory fitness was evaluated by trained personnel using the modified Bruce protocol on a Woodway PPS treadmill (Woodway, Waukesha, WI). Participants’ birth date, height, weight, sex, and mask size were inputted into the Quark b2 computer software. Holding onto the handrails was strongly discouraged during the test. Standardized verbal encouragement was given 1.5 minutes after the start of

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every phase to all participants. Verbal encouragement ceased as participants neared the termination of the assessment. Inspired and expired gases were analyzed using a Cosmed Quark b2 indirect calorimetry metabolic system (Cosmed S.r.I, Rome, Italy). Participants wore a fitted, silicone rubber facemask (Hans Rudolph, Shawnee, KS) that covered their noses and mouths. Respiratory gas analysis on the volume of oxygen uptake (VO2 ) and carbon dioxide output (VCO2 ) was continuously performed through a bidirectional digital turbine flow meter that was fixed to the front of the mask and connected to the analyzer unit via a capillary line R ). The Cosmed Quark b2 system utilized (Nafion Permapure a zirconia oxide heater and infrared analyzer to determine O2 and CO2 concentrations, respectively. Calibration of the metabolic system was conducted according to the manufacturer’s guidelines (Cosmed S.r.I, Rome, Italy) prior to each test with ambient air and standard gases of known O2 (16.1%) and CO2 (5%) concentrations. The volume turbine was calibrated using a syringe of known volume (3.0 liters) over a range of flows. Temperature of the cardiorespiratory room was maintained at 21◦ C. Peak VO2 was determined by taking the highest average value during a 30-second period and expressed in relative (ml/kg/min) units. Other cardiorespiratory fitness parameters that were collected include duration of the maximum test and respiratory exchange ratio (RER). Heart rate was measured using a Polar heart rate transmitter (Kempele, Finland). The Borg Rating of Perceived Exertion (RPE) scale33 was administered at termination of the test. The scale ranged from 6 (no exertion at all) to 20 (maximal exertion). This scale has been found to be a reliable indicator of perceived exertion in children exercising at ventilatory threshold (α = 0.78).34 The cardiorespiratory fitness test was volitionally terminated by the participants. The experimenter did not provide further encouragement or support when participants expressed their desire to end the assessment. The cardiorespiratory fitness test was terminated by the experimenter only when physiological symptoms deemed it necessary. VO2max was reached when participants’ heart rate was equal to or greater than 85% of their maximum heart rate (220 beats/minute–age) and if their RER was greater than 1.0.35 The Cosmed Quark b2 has been validated and shown to be a reliable instrument for the purpose of measuring cardiorespiratory and metabolic variables.36,37 To ensure high inter rater reliability and monitor potential bias, an audio recorder was used to document baseline and follow-up fitness tests.

Task Self-Efficacy Task self-efficacy (SE) was assessed using the 18-item Self-Efficacy Scale (adapted from McAuley & Milhalko38) to evaluate participants’ confidence to successfully perform increasing intensities and durations of physical activity. It used a Likert scale ranging from 0% (no confidence at all)

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to 100% (completely confident). Scores were summed and divided by the total number of items for the domains of easy, moderate, and vigorous intensities. In the same manner, vigorous task SE scores for the vigorous intensity domain were calculated by isolating the corresponding items. Higher values indicate efficacious beliefs. In this study, the reliability of the overall scale and the vigorous subcomponent at baseline (α = 0.981, 0.976) and follow-up (α = 0.976, 0.972) were excellent.


Manipulation, Contamination, and Motivation Check Purpose built items were constructed by the authors in order to determine if participants paid attention and retained the information conveyed in their respective DVD (manipulation inspection), monitor for any potential contamination between groups (contamination inspection), and to gauge participants’ motivation to participate in the study (motivation inspection). The manipulation inspection was constructed to determine if participants paid attention and retained the information conveyed in the respective DVD through four binary (true or false, yes or no) and two short answer questions. Items were also created to monitor for any potential contamination between groups by inquiring whether participants knew anyone else in the study. A motivation assessment was generated to gauge participants’ motivation in the study by questioning whether participants wanted to participate in the study. Higher values indicate greater attentiveness and retention, contamination, and motivation to participate in the study on the manipulation, contamination, and motivation constructs, respectively. Power Calculation and Statistical Analysis A total sample size of 50 participants (25 in each condition) was required to complete the study. This sample was projected to provide a power of 93% and to detect at least a large effect (Cohen’s d = 0.82) in peak VO2 between the experimental and control groups, assuming a statistical significance level of α = 0.05.41,42 Specifically, the study was powered to detect a 29% net difference in peak VO2 between the experimental (eg, 27 ml/kg/min) and control groups (eg, 23 ml/kg/min, SD = 1.0) at follow-up. Sample size was determined by comparing the mean difference of other research testing the effects of psychological-based interventions on peak VO2 with a different population.32 To verify equivalence between the experimental and attention control groups at baseline, independent-samples t-tests and chi-square (X 2) tests were used to analyze demographics, manipulation, contamination, motivation, cardiorespiratory fitness parameters (peak VO2 , duration, RER, RPE, and heart rate), and self-efficacy. Mean and variability scores were first calculated for cardiorespiratory fitness parameters and task self-efficacy. Variability scores were calculated by subtracting each participant’s score from the mean score of the group they were randomized to. These data were ana-

lyzed for group by time interaction effects using repeated measures analysis of variance (ANOVA). If baseline differences were found for any of the demographic, manipulation, contamination, motivation variables, then a repeated measure ANCOVA was conducted on these data. Furthermore, if group differences at baseline in cardiorespiratory fitness or self-efficacy were found, then ANCOVA was used on these follow-up data controlling for baseline scores. Bivariate correlations were performed to examine the relationships among variables at baseline and follow-up. The level of significance was accepted at p < .05 for all statistical tests.43 Data were analyzed using SPSS for Windows version 17 (IBM, United States).

RESULTS Group Equivalency Baseline characteristics of the sample, by group allocation, are presented in Table 1. Experimental and control groups were comparable at baseline for demographic characteristics and psychosocial outcomes (PedsQofL and PAQ-C). There were no significant differences between groups for self-efficacy or for any of the cardiorespiratory fitness parameters, with the exception of mean (Table 2) and variability RER (Table 3). Analyses also revealed that there was no significant difference in the percentage of correct responses on the manipulation, contamination, and motivation inspection TABLE 1 Demographic Characteristics of Participants at Baseline Experimental group

Control group

N = 25

N = 24

13 boys/12 girls

13 boys/11 girls

M Age (years) BMI (kg/m2) BMI percentile PAQ-C PedsQofL Manipulation check (% correct answers on content quiz) Contamination check Motivation check (willingness to participate)

13.04 33.06 98.19 2.21 1.22 92.00

SD 2.07 7.22 1.84 0.50 0.73 15.68

M 12.25 31.62 98.46 2.32 1.15 91.30

SD

p

2.13 5.34 1.10 0.59 0.51 12.17

.20 .43 .54 .52 .74 .87

20.00%

4.30%

.11

84.00

87.00

.34

BMI, Body mass index; PAQ-C, Physical Activity Questionnaire for Children; PedsQofL, Pediatric Quality of Life.

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PEER MODELING AND OBESE YOUTH TABLE 2 Tests of Comparisons for Experimental and Control Groups at Baseline and Follow-up for Mean Cardiorespiratory and Efficacy Parameters.


Baseline

Testb

Follow-up

Variable

Experimental

Control

Testa p

Experimental

Control

p

η2

Peak VO2 (mL/kg/min) Duration (min) RER HR (bpm) RPE Task SE (Percent %) Vigorous Task SE (Percent %)

23.85 (7.18) 12.66 (1.89) 1.04 (0.14) 173.67 (21.87) 13.96 (2.51) 60.22 (24.43) 46.32 (27.91)

23.16 (6.20) 12.56 (1.90) 0.98 (0.08) 172.77 (15.98) 13.95 (2.34) 59.05 (24.73) 44.68 (26.17)

0.7 0.85 0.05 0.95 0.86 0.66 0.58

24.34 (7.14) 12.92 (1.42) 1.05 (0.11) 178.58 (13.07) 15.08 (2.12) 62.37 (22.53) 47.54 (26.36)

23.51 (6.47) 12.57 (2.00) 0.99 (0.09) 173.50 (17.11) 14.32 (1.99) 58.20 (23.90) 39.09 (28.88)

0.88 0.43 0.39 0.35 0.261 0.56 0.23

0.001 0.014 0.017c 0.02 0.03 0.01 0.03

Note. Mean (SD). VO2 , Ventilatory oxygen; RER, Respiratory exchange ratio; RPE, Rating of perceived exertion; SE, Self-efficacy. differences from independent-samples t-tests. bTime × group interactions from repeated measures ANOVAs. cANCOVA (controlling for baseline RER) due to significant group differences in RER at baseline. aGroup

between the experimental and control group at baseline and follow-up.

lated. These relationships were similar at follow-up, except duration was also associated with HR.

Mean Score Differences

Relations among Variables Relationships between mean scores of cardiorespiratory fitness parameters and task self-efficacy variables at baseline and follow-up are presented in Table 4. Peak VO2 and duration were highly and positively correlated with all other cardiorespiratory fitness and task self-efficacy parameters at baseline. Heart rate, RPE, and RER were not associated with task self-efficacy parameters at baseline. Most of these relationships existed at follow-up. Correlations for variability scores for cardiorespiratory fitness parameters and task self-efficacy variables at baseline and follow-up were also conducted, but are not presented. Duration was associated with peak VO2 and RPE. Task selfefficacy and vigorous task self-efficacy were strongly corre-

Repeated measures ANOVAs for the mean scores of cardiorespiratory fitness parameters and task self-efficacy between groups and baseline and follow-up did not reach significance (see Table 2). Effect sizes for duration, heart rate, RPE, and vigorous task self-efficacy were small but favoring the experimental peer modeling condition.

Variability Scores Differences Similar analyses for variability scores for cardiorespiratory fitness parameters and task self-efficacy were not significant between groups and baseline and follow-up (see Table 3). Time by group interaction trend effects for duration and heart

TABLE 3 Tests of Comparisons for Experimental and Control Groups at Baseline and Follow-up for Variability Scores of Cardiorespiratory and Efficacy Parameters. Baseline

Testb

Follow-up

Variable

Experimental

Control

Testa p

Experimental

Control

p

η2

Peak VO2 (mL/kg/min) Duration (min) RER HR (bpm) RPE Task SE (Percent %) Vigorous Task SE (Percent %)

5.74 (4.15) 1.43 (1.20) 0.11 (0.08) 16.36 (14.11) 1.88 (1.62) 20.83 (12.00) 24.03 (13.28)

4.19 (4.47) 1.42 (1.23) 0.07 (0.05) 12.75 (9.21) 1.77 (1.48) 20.18 (13.57) 22.08 (13.16)

0.22 0.95 0.01 0.40 0.74 0.54 0.53

5.81 (3.96) 1.04 (0.95) 0.08 (0.07) 11.44 (5.87) 1.46 (1.51) 16.98 (14.38) 21.08 (16.29)

4.48 (4.57) 1.48 (1.31) 0.08 (0.04) 14.23 (8.98) 1.44 (1.33) 19.36 (13.32) 22.69 (17.13)

0.80 0.09 0.02 0.07 0.87 0.45 0.39

0.001 0.06 0.31c 0.07 0.001 0.013 0.017

Note. Mean (SD). VO2 , Ventilatory oxygen; RER, Respiratory exchange ratio; RPE, Rating of perceived exertion; SE, Self-efficacy. differences from independent-samples t-tests. bTime × group interactions from repeated measures ANOVAs. cANCOVA (controlling for baseline RER) due to significant group differences in RER at baseline. aGroup

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DE JESUS AND PRAPAVESSIS TABLE 4 Correlations for Cardiorespiratory Fitness Parameters and Task Self-efficacy Variable.

Peak VO2 HR Duration RPE RER Task SE Vigorous task SE

Peak VO2

HR

Duration

RPE

RER

Task SE

Vigorous task SE

— 0.41∗∗ 0.77∗∗ 0.15 0.31∗ 0.34∗ 0.28

0.39∗∗ — 0.57∗∗ 0.28 0.54∗∗ 0.10 0.20

0.76∗∗ 0.54∗∗ — 0.23 0.45∗∗ 0.37∗ 0.35∗

0.34∗ 0.25 0.40∗∗ — 0.21 0.09 −0.07

0.38∗∗ 0.53∗∗ 0.52∗∗ 0.35∗ — 0.35∗ 0.38∗

0.42∗∗ 0.17 0.36∗ 0.16 0.19 — 0.86∗∗

0.45∗∗ 0.17 0.41∗∗ 0.13 0.19 0.94∗∗ —


Note. Each cell above the diagonal indicates relationships at baseline. Each cell below the diagonal indicates relationships at follow-up. VO2 , Ventilatory oxygen; HR, Heart rate; RPE, Rating of Physical Exertion; RER, Respiratory Exchange Ratio; SE, Self-efficacy. ∗ p < .05, ∗∗ p < .01 for significant group differences.

rate yielded moderate effect sizes, favoring the experimental peer modeling condition.

DISCUSSION The purpose of this study was to determine the effect of a peer modeling intervention on cardiorespiratory fitness and self-efficacy in obese youth completing a maximal treadmill test. With respect to mean scores, participants who viewed the peer modeling intervention did not significantly improve with respect to cardiorespiratory fitness parameters and selfefficacy when compared to participants in the attention control group, from baseline to follow-up. Nevertheless, small effects favoring the peer modeling condition were seen for duration, HR, RPE, and task and vigorous task self-efficacy. Visual inspection of the data show that compared to the attention control condition, those in the peer modeling condition showed slightly larger increases for the abovementioned variables between baseline and follow-up assessments. For task self-efficacy constructs, increases were seen in the experimental group while decreases were seen in the control group, from baseline to follow-up. With respect to variability scores, similar non-significant treatment effects were found. Moderate size trend effects favoring the peer modeling condition were found for duration and heart rate, while small effects favoring the peer modeling condition were found for the task self-efficacy constructs. Visual inspection of the data shows that from baseline to followup, variability for these parameters decreased in the experimental group and slightly increased in the control group from baseline to follow-up. Taken together, these findings suggest peer modeling is somewhat successful at reducing variability and improving the consistency in the assessment of both cardiorespiratory fitness parameters and task self-efficacy. Changes in inter- and intra-rater reliability could be considered sources to decrease variation in the sample; however, it should be noted that this is unlikely since experimenters and participants were blinded to group allocation and an audio recorder was used to ensure consistency.

As previously mentioned, interventions rooted in peer modeling have been found to be successful in various populations of interest.27,28,29,32 These findings, taken together, question why the current peer modeling intervention was not as effective at improving cardiorespiratory fitness parameters and self-efficacy as expected. The strength and delivery of the peer modeling intervention, psychosocial state, and motivation are factors that deserve attention to understand the non-significant findings of the current study. Learning by observation involves four separate processes: attention, retention, production, and motivation.21 In order to maximize the observer’s chances of imitating the model’s behavior, the peer modeling intervention material in the present study employed several applicable sub-processes that govern attention and retention in observational learning. First, the intervention provided observers with clear and concise information concerning the psychological and physiological expectations and coping strategies before, during, and after the maximal exercise test and the importance of maximal exertion. Second, the models possessed characteristics that were comparable to the observers including sex and initial negative cognitions and incompetence. Schunk and colleagues44 have found that peer coping models were particularly beneficial for youth doubtful of their abilities. In line with the results of the manipulation assessment, participants in both groups attended to and retained the information conveyed in their respective DVDs. Perhaps, if the intervention was delivered at the same time the cardiorespiratory fitness test unfolded, as opposed to before the start of the test, the attention and retention of the peer model’s information would have been enhanced. This in turn, may have enabled the experimental group participants to score significantly higher than their attention control counterparts on the targeted fitness parameters and self-efficacy constructs. Although attention and retention are necessary for the acquisition or learning of the peer model’s behavior, confidence in producing the act and motivation to perform the act control demonstrating the behavior.21 With respect to confidence in producing the model behavior, our data show that participants’ self-efficacy scores (range 58%–62%)



were uniformly low throughout the experiment and were resistant to change—as highlighted by the fact that our peer modeling intervention had a minimal non-significant effect in increasing these self-efficacy scores. The correlations reported between cardiorespiratory fitness parameters and self-efficacy further clarifies the non-significant findings and strengthens the tenets of observational learning. Specifically, task self-efficacy was positively and moderately related with peak VO2 , duration, and RER. This indicates that efficacious beliefs were associated with better fitness performance, though this relationship was weaker at follow-up. Vigorous task self-efficacy mirrored the relationship with these cardiorespiratory fitness parameters. Another related, plausible reason for the statistically nonsignificant results involves the psychosocial welfare of a pediatric obese population. Psychosocial welfare includes attitude, self-esteem, and perceived and actual competence, among others. Earlier research has contended that overweight and obese youth reported poorer self-esteem, actual physical competence, less positive attitude, and more perceived barriers towards physical activity, compared to normal weight youth.45,46,47,48 Youth are more likely to engage in physical activity if they perceive they were competent in this regard.49,50,51 To demonstrate, perceived sports competence explained 18% and 30% of the variance of physical activity and fitness in adolescents, respectively.52 Furthermore, cardiovascular fitness was higher in youth who reported greater competence.50 Therefore, social and psychological distress may have implications on the cardiorespiratory fitness assessments of the obese youth in this study; however these variables were not assessed or manipulated. Improving the perception of the obese child’s physical competency may be a necessary first step before a peer modeling intervention of this kind is able to work effectively. With respect to motivation to perform the model’s behavior, individuals are inclined to model an action if there are valued and rewarding outcomes.53 The present study did not offer incentives as the purpose was to exclusively test the effectiveness of a peer modeling intervention. However, some individuals are typically referred by their physician to complete a maximal incremental exercise test due to diagnostic necessity. Thus, these individuals are subjected to a potent source of motivation from their physician and have an opportunity to comprehend the medical relevance and importance of physical exertion during the maximal incremental exercise test. This circumstance did not present itself in this study, but likely played a key role in the positive findings reported by Maddison and colleagues32 in heart failure patients. Moreover, the participants in this study were unlikely to be motivated by an outcome such as accurate peak VO2 or in pursuit of intangible benefits, such as health or fitness, and by extension, accurate peak VO2 values, especially at the expense of gratification.17 Motivating obese youth to perform physically demanding tasks in the absence of tangible or medical reinforcement is challenging.

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The current study had several methodological strengths. First, the study implemented a peer modeling intervention, which was yoked in observational learning (social cognitive theory). Theoretically driven interventions provide a framework as to which constructs to address in order to effect change in performance and psychological condition. Second, the study was designed with scientific validity in mind; participants were randomized according to a stratification scheme, group allocation was concealed to participants and experimenters, and contamination and manipulation assessments were used and checked. Lastly, the study aimed at developing an intervention (ie, peer model DVD) that could be put into practice by clinicians, exercise physiologists, and researchers testing young, obese patients. Despite these strengths, there were a few limitations to the present study that must be acknowledged. Involvement, for instance, was voluntary, thus participants were self-selected and generalizability to the pediatric obese population is limited. Next, individuals of this demographic requiring an assessment of their cardiorespiratory fitness are typically referred by a member of their healthcare network. Participants were not directly referred by doctors and hence, this study lacked that form of ecological validity. Finally, the sample size was not powerful enough to detect the small group differences in cardiorespiratory fitness and self-efficacy from baseline to follow-up. The aim of this study was to find an effective and feasible manner to manipulate a key psychosocial process, selfefficacy, of obese youth and attain peak VO2 values that were reflective of their true physical fitness capacity. Although peer modeling has been effective in many domains, a peer modeling intervention was not associated with statistically significant improvements in mean scores for either fitness or self-efficacy parameters in the obese pediatric children. There was, however, some evidence that the peer modeling intervention reduced the variability and improved the consistency in the assessment of both cardiorespiratory parameters and self-efficacy. Successfully manipulating the cognitions and fitness performance of obese youth is difficult possibly due to the uniformly low confidence to perform a maximal fitness that appears resistant to change because of this population’s underlying comorbidities and psychological distress towards physical activity; and the lack of immediate valued rewards for imitating the targeted behavior. Ultimately, further research is warranted to enhance the effectiveness of this mode and delivery of learning. In the clinical setting, standard of care surrounding cardiorespiratory fitness assessments may involve brief education and familiarization procedures. However, an intervention, as proposed, provides additional information and acquaints the patient with psychological and physiological responses and specific coping strategies. Improving the accuracy and eliminating discrepancies associated with cardiorespiratory fitness assessment in obese youth is crucial to conducting sound science and ensuring that clinically diagnostic and prognostic

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knowledge is available to clinicians making important life decisions.


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