Perceptual & Motor Skills: Perception 2014, 119, 3, 884-900. © Perceptual & Motor Skills 2014
DEVELOPMENT OF THE COLOR SCALE OF PERCEIVED EXERTION: PRELIMINARY VALIDATION1 THAIS H. S. SERAFIM AND ANDREA C. TOGNATO Department of Physical Education, São Paulo State University, Rio Claro, Brazil PRISCILA M. NAKAMURA Department of Physical Education, São Paulo State University, Rio Claro, Brazil Federal Institute of Education, Science and Technology South of Minas Gerais, Campus Muzambinho, Brazil MARCOS R. QUEIROGA
FÁBIO Y. NAKAMURA
Department of Physical Education Midwest State University UNICENTRO, Guarapuava, Brazil
Center of Physical Education and Sport State University of Londrina, Londrina, PR, Brazil
GLEBER PEREIRA
EDUARDO KOKUBUN
Núcleo de Ciências Biológicas e da Saúde, Universidade Positivo, Curitiba, Brazil Programa de Pós-Graduação em Educação Física, Universidade Federal do Paraná, Curitiba, Brazil
Department of Physical Education São Paulo State University, Rio Claro, Brazil
Summary.—This study developed a Color Scale of Perceived Exertion (RPEcolor scale) and assessed its concurrent and construct validity in adult women. One hundred participants (18–77 years), who were habitual exercisers, associated colors with verbal anchors of the Borg RPE scale (RPE-Borg scale) for RPE-color scale development. For RPE-color scale validation, 12 Young (M = 21.7 yr., SD = 1.5) and 10 Older (M = 60.3 yr., SD = 3.5) adult women performed a maximal graded exercise test on a treadmill and reported perceived exertion in both RPE-color and RPEBorg scales. In the Young group, the RPE-color scale was significantly associated with heart rate and oxygen consumption, having strong correlations with the RPEBorg scale. In the Older group, the RPE-color scale was significantly associated with heart rate, having moderate to high correlations with the RPE-Borg scale. The RPEcolor scale demonstrated concurrent and construct validity in the Young women, as well as construct validity in Older adults.
Perceived exertion is defined as the effort expended in performing a physical task (Marcora, 2009). To assess perceived exertion during aerobic exercise, several scales of perceived exertion have been developed (Borg, 1970; Robertson, Goss, Rutkowski, Lenz, Dixon, Timmer, et al., 2003; Persinger, Foster, Gibson, Fater, & Porcari, 2004; Borg & Kaijser, 2006; Borg, Address correspondence to Thais Helena Sayegh Serafim, Instituto de Biociências, Departamento de Educação Física, Universidade Estadual Paulista, Av. 24-A, n 1515, Bela Vista CEP: 13506-900, Rio Claro-SP, Brazil or e-mail ([email protected]). 1
DOI 10.2466/27.06.PMS.119c28z5
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2007) and have been used to prescribe and to monitor exercise intensity (Borg, 1982, 1990; Seiler & Kjerland, 2006). In addition, studies have demonstrated the effectiveness of the ratings of perceived exertion (RPE) scales in monitoring exercise intensity for both adults (Ceci & Hassmén, 1991; Robertson, Moyna, Sward, Millich, Goss, & Thompson, 2000; Karavatas & Tavakol, 2005) and the elderly (Dunbar & Kalinski, 2004; Shigematsu, Ueno, Nakagaichi, Nho, & Tanaka, 2004; Groslambert, Grange, Perrey, Maire, Tordi, & Rouillon, 2006). The Borg RPE scale (RPE-Borg scale) is the most commonly used to assess perceived exertion (Borg, 1998). It consists of 15 numerical descriptors with labels ranging from 6 to 20, as well as corresponding verbal descriptors. Borg RPE is correlated with heart rate (HR), oxygen consumption (V̇ O2), and blood lactate concentration in progressive exercise intensities during graded protocol tests (Borg, 1982; Robertson, Goss, & Metz, 1998; Chen, Fan, & Moe, 2002). Borg (1998) stated that the standard scale has some limitations, such as respondents' understanding and interpreting the ratings. For instance, changes in the verbal anchors' positioning and changes in the words may compromise understanding of perceived exertion and the interpretation of the scale in people who have low educational levels or visual or cognitive impairment. Therefore, other information in RPE scales should be provided to assist the evaluation of the perceived exertion. Some scales have used pictures associated with each workload, e.g., the OMNI-RPE scale (Robertson, Goss, Boer, Peoples, Foreman, Dabayebeh, et al., 2000; Nakamura, Perandini, Okuno, Borges, Bertuzzi, & Robertson, 2009; Guidetti, Sgadari, Buzzachera, Broccatelli, Utter, Goss, et al., 2011). However, these pictures can be difficult for those with visual or cognitive impairments. Thus, another type of visual resource might help such populations. Different colors can be associated with stress, since they are related to several emotional states and human perceptions regarding external clues (Crozier, 1996; Ou, Luo, Woodcock, & Wright, 2004; Gao & Xin, 2006; Carruthers, Morris, Tarrier, & Whorwell, 2010). It has been suggested that the origins of color vision among primates stems from the advantage it confers in being able to identify targets such as food against dappled or variegated backgrounds (Mollon, 1989). According to Akers, Barton, Cossey, Gainsford, Griffin, and Micklewright (2012), color perception in humans is associated with the survival instinct—for example, lower total mood disturbance and RPE was found during a cycling task performed with exposure to the color green compared to colors gray and red (Akers, et al., 2012). Furthermore, feelings of anger were heightened after the exposure to red compared to the other conditions. The use of colors can enhance the manner in which people perceive and recognize objects in the everyday world (Tanaka, Weiskopf, & Williams,
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2001). Colors have already been used in RPE scales for patients in rehabilitation (Trojan & Finch, 1997). However, that RPE scale used a small range of three colors. Given that colors can improve the perception of the environment and related situations, the use of colors to represent different exercise intensities in RPE scales may assist with the evaluation and interpretation of perceived exertion by improving the mapping of exercise-related feelings. Moreover, declines in cognitive function can affect the ability of an individual to assess the effort properly (Groslambert & Mahon, 2006). With aging, there is a reduction in cerebral blood flow that may lead to declining function (Ogoh & Ainslie, 2009). Therefore, older people may have difficulty using perception scales (Andrade, Pereira, & Sousa, 2006) that have numerical and verbal descriptors. The development and validation of a new RPE scale with colors is of particular significance for older people who may have difficulty using conventional perception scales. According to Robertson, Goss, Dubé, Rutkowski, Dupain, Brennan, et al. (2004), a valid RPE scale should be able to: (1) distinguish the perceived exertion related to different parts of the body involved in exercise (overall body, main skeletal muscles involved, and cardiorespiratory muscles); (2) distinguish the different exercise intensities; and (3) correlate with physiological responses. Therefore, the goal of the present study was to develop the RPE-color scale and to test its concurrent and construct validity in young adult and older adult women. Hypothesis 1. The RPE-color scale will significantly discriminate exercise intensities in different parts of the body involved during walking, i.e., exertion of the overall body, exertion in the legs, and exertion in the chest. Hypothesis 2. Scores on the RPE-color scale must be correlated positively with HR, V̇O2, and the RPE-Borg scale in the graded treadmill exercise test. Research Goal. Assess relations between the validity of the RPEcolor scale and age groups. METHOD Participants There were two samples in this study, one for the development of the RPE-color scale and another one for its validation. The Local Research Ethics Committee approved the study and all participants provided written informed consent. One hundred men (44%) and women (56%), ages 18 to 77 years (34% 18–40 years, 34% 41–60 years, and 33% 61–77 years), were interviewed. They were asked about the preferred color sequences for each exertion level. Par-
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ticipants were recruited from physical activity groups of SESI (Social Service of the Industry, Brazil), Health Units for Exercise, and students from São Paulo State University (Rio Claro-SP, Brazil). All the participants were habitual exercisers. For assessing the validity of the scale, 12 young adult women (Young sample; M age = 21.7 yr., SD = 1.5; M weight = 58.7 kg, SD = 7.8; M height = 161 cm, SD = 10.0) and 10 older adult women (Older group; M age = 60.3 yr., SD = 3.5; M weight = 69.5 kg, SD = 7.7; M height = 154 cm, SD = 10.0) were evaluated. The sample size was calculated considering α level of .05, power of .95, effect size of .90, and correlation coefficient of .85 (Lima, 2007). The required sample size calculated was 8 participants for each age group. Considering the possibility of losing 20% of the sample, a minimum of 10 participants for each group was included. All the participants were habitual exercisers and half of the older adults had low educational status, which means that they had studied until the middle school. Given that the sample of the development process of the scale included only adults, and the color preferences for the scale did not differ between sex (Table 2), only young adult women were included for the validation process as a matter of convenience. As older adults may have difficulty reporting perceived exertion, a preliminary testing of the RPE-color scale was performed to further validate it to such population use. RPE-color Scale Development For the RPE-color scale development, the seven colors of the rainbow were used as a reference because this is a well-known optical phenomenon. However, to offer a wider range of shades, the colors indigo and violet were replaced by the colors light blue and lilac, respectively. The standardization of the colors' shades was performed using the Red, Green, and Blue (RGB) scale. This scale has a range from 0: Darkest to 225: Lightest. Table 1 presents the tonality of the colors used in this study. TABLE 1 DESCRIPTION OF THE COLORS ACCORDING TO THE RED, GREEN, AND BLUE SCALE Colors
Red
Green
255
204
255
0
255
255
Yellow
255
255
0
Orange
0
Lilac Light blue
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Blue
255
153
Green
0
204
0
Blue
0
0
255
Red
255
0
0
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For data collection, a copy of the RPE-Borg scale (6–20) was used. Velcro® was attached next to the verbal anchors (6, 7, 9, 11, 13, 15, 17, 19, and 20) to make possible setting color strips on the RPE-Borg scale. Strips of the colors lilac, light blue, blue, green, yellow, orange, and red were made and attached with the other half of the Velcro® to allow participants to organize the order of the colors on the RPE-Borg scale according to their own association between color and perceived exertion. The numerical descriptors 8, 10, 12, 14, 16, and 18 represented transitions between intensity levels of the scale (Fig. 1). For the association of the color strips with the RPE-Borg scale, the participants received instructions about the scale and answered the following question: “Imagine that you are exercising. We would like you to estimate your perceived exertion, i.e., the effort expended in performing an exercise (e.g., light, heavy). It should take into account sensations of exertion on your body, your legs, and your breathing. Now examine this scale (RPE-Borg scale). We would like you to interpret it considering number 6 the white color, which corresponds to “no exertion at all,” and number 20 the black color, which corresponds to “maximal exertion.” The other numbers on the scale represent successive physical exertion levels, from the lightest to the heaviest effort. Then, we would like you to observe these strips in different colors and try to figure out what kind of sensation they bring to you. So, try to associate the strips with the different intensities of effort, placing them on the verbal anchors that best correspond to your sensations. Are there any questions?” RPE-color Scale Validation A day before the test, the participants were requested to not participate in vigorous activity and not to consume alcohol or caffeine, and have a good night of sleep. All participants attended the laboratory once and answered the Physical Activity Readiness Questionnaire (PAR-Q; American College of Sports Medicine, 2006). Subsequently, body mass (Welmy R-110, Santa Bárbara d'Oeste, Brazil), body height (WelmyR-110, Santa Bárbara d'Oeste, Brazil), heart rate at resting condition (Polar T31, Finland), and blood pressure (portable wrist monitor Bioland 3001, China) were measured. The participants were habituated to the treadmill (Inbramed Millennium ATL, Porto Alegre, Brazil) for 5 min., walking at 4 km·hr−1 (1% slope). The room temperature was kept constant at 25°C. After 10 minutes of rest, the experimental session was initiated. RPE-color scale for validation process.—The RPE-color scale did not include the numbers and the verbal anchors of the RPE-Borg scale. In addition, the RPE-color scale was shown to the participants in the opposite direction to the RPE-Borg scale: the white color corresponding to the verbal anchor “no exertion at all” at the bottom, and the black color correspond-
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ing to the verbal anchor “maximal exertion” at the top (Fig. 1, right panel). This approach was used to facilitate the visualization of the gradual increase of exercise intensities, i.e., the lowest value at the bottom, and the highest value at the top of the RPE-color scale. Ratings of perceived exertion.—During the incremental test, participants estimated the RPE for the overall body (RPE-Overall), for peripheral perceptions in the legs (RPE-Legs), and for respiratory-metabolic perceptions in the chest (RPE-Chest). First, participants estimated the perceived exertion on the RPE-color scale (Fig. 1, right panel) and afterward using the RPE-Borg scale. This order was fixed in all reports to ensure that ratings of the RPE-color scale would not be based on verbal anchors of the RPE-Borg scale. Instructions about the RPE scales.—Before the tests, the following instructions were given to participants: “These scales assess perceived exertion, i.e., the effort expended in performing an exercise (e.g., light, heavy). You should take into account sensations of exertion on your whole body, your legs, and your breathing. While you are walking, we will show you the color scale (RPE-color scale) first, and then we will show you the Borg scale (RPE-Borg scale). Now look at these scales. In the color scale, the white color (bottom) represents ‘no exertion at all’ and the black color (top) represents ‘maximal exertion.’ In the Borg RPE scale, the number 6 represents ‘no exertion at all’ and the number 20 represents ‘maximal exertion.’ We will ask you to point to colors (considering all colors of the RPE-color scale) and numbers (considering all numbers of the RPE-Borg scale) that express how you are feeling. We would like you to estimate your perceived exertion related to your whole body, your legs, and your chest. Remember that there is no right or wrong answer. Are there any questions?” Experimental protocol.—The participants performed an incremental treadmill test starting at 5.5 km.hr−1 and 6% or 2% slope for the Young and Older groups of adult women, respectively. Such different slopes could decrease the range of older adults' exercise test. Every 2 min., there were increments of 2% on the treadmill slope without changing the velocity. The criteria of the American College of Sports Medicine (2006) for test interruption were adopted and a physician observed the tests. In the last 30 sec. of each stage, heart rate and V̇ O2 (VO2000, Medical Graphics Corporation, St. Paul, USA) were recorded. The RPE in both scales were obtained in the second minute of each stage. Before all RPE estimations on the RPE-color scale, the information that the bottom and the top end of the scale corresponded to the verbal anchors “no exertion at all” and “maximal exertion,” respectively, was provided to the participants. Whereas the RPE-color scale comprised only the color gradient, it was necessary to associate the colors with the numbers of the RPE-Borg scale for analysis purposes. Thus, when the participants pointed to a color to
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estimate the RPE, a mark was made at the indicated site. Subsequently, transparent paper with the corresponding numbers of the RPE-Borg scale was placed over the RPE-color scale. Each RPE marking of the participant was assigned a number according to the RPE-Borg scale. The criterion for interruption of the test was volitional exhaustion for the Young group. For the Older group, 8 of the 10 interrupted the test at volitional exhaustion, while two participants interrupted the test at submaximal HR. After the end of the test, the participants remained in the laboratory for a few minutes and were examined by the physician. Data Analysis For the RPE-color scale development, a qualitative analysis of responses from the participants was performed. The frequency of color responses for each position of the RPE-Borg scale was analyzed for both sexes and for the total sample. The RPE-color scale was developed using the highest frequency color chosen by the total sample corresponding to each exertion level. For the RPE-color scale validation, the analyses were separated by age group. Descriptive data were calculated as means and standard deviations (SD). The concurrent validity was tested using linear regression analysis and linear mixed-model analysis. The linear regression analysis by the least squares method was performed for the RPE-color scale with the physiological variables. The linear mixed-model analysis, an extension of the general linear model, does not require observations to be independent with constant variance, so repeated-measures can be analyzed, and it allows for a large number of covariate structures, the inclusion of cases with incomplete data, and for data to be collected over time (Norusis, 2004). Therefore, data from all exercise stages performed by each participant were included in the analysis. The HR and V̇ O2 data were the dependent variables, and RPE-color ratings, RPE-Borg ratings, and exercise stages were defined as covariates. Moreover, RPE-color and RPE-Borg ratings were defined as fixed variables and the load as a random variable. Furthermore, the construct validity was tested using linear regression analysis by the least squares method between RPE-color and RPE-Borg scales. For all analyses, the significance level was set at p < .05 and the statistical functions of Microsoft Office Excel 2007 and STATISTICA 6.0 statistical package were used. RESULTS RPE-color Scale Development The RPE-color scale according to the sample's choices is presented in Fig. 1 (left panel). There was a high consistency between sexes for the color preferences at each level of perceived exertion (Table 2).
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FIG. 1. Color Scale of Perceived Exertion (RPE-color scale) developed in this study (left panel) and RPE-color scale as validated (right panel).
RPE-color Scale Validation The descriptive data from the incremental test by age group is shown in Table 3. Table 4 presents the analysis for testing the concurrent validity of the RPE-color scale. There were high correlations between the RPEcolor scale and HR (.69–.71) and V̇ O2 (.77–.85) for the Younger group. For the Older group, there were weak correlations between the RPE-color scale and HR (.39–.41) and V̇ O2 (.22–.32). Table 5 presents the multilevel mixed model analysis for the physiological variables to the RPE-color and RPE-Borg scales by age group. For the Younger group, the RPEs from both scales were significant (p < .05) positive linear functions of HR and V̇ O2. For the Older group, RPE-Overall from both scales and RPE-Legs from the RPE-color scale were significant (p < .05) positive linear functions of HR. TABLE 2 HIGHEST FREQUENCIES (%) OF COLOR ASSIGNMENTS TO EACH EXERTION LEVEL OF RPE-BORG SCALE BY SEX Exertion
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Color
Men (n = 44)
Women (n = 56)
Total (N = 100)
7
Lilac
70
64
67
9
Yellow
41
39
40
11
Orange
41
34
37
13
Light blue
39
36
37
15
Green
36
45
41
17
Blue
43
46
45
19
Red
75
70
72
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T. H. S. SERAFIM, ET AL. TABLE 3 DESCRIPTIVE STATISTICS BY TREADMILL SLOPE FOR RPE AND PHYSIOLOGICAL VARIABLES Younger Group Variable
M
SD
Min.
Slope (%)
11.8
4.5
RPE-Overall (Color)
11.7
RPE-Overall (Borg) RPE-Legs (Color)
Older Group Max.
M
SD
Min.
6
24
6.1
3.4
2
14
4.1
6
20
11.8
4.9
6
20
12.9
3.8
6
20
13.6
3.6
6
20
12.8
4.3
6
20
11.6
4.4
6
20
RPE-Legs (Borg)
13.9
3.8
7
20
13.7
3.3
6
20
RPE-Chest (Color)
12.3
4.3
6
20
11.8
4.5
6
20
RPE-Chest (Borg)
13.0
3.9
6
20
166 HR (beats·min.−1) −1 −1 ̇ VO2 (ml·kg ·min. ) 27.2
22.2
98
207
13.2 143
Max.
3.1
6
20
13.3
115
168
6.0 16.4 38.9 20.7 6.4 10.4 47.1 Note.—Color = RPE-color scale; Borg = RPE-Borg; HR = heart rate; V̇ O2 = oxygen consumption.
The analysis for testing the construct validity of the RPE-color scale is shown in Table 6. The correlations between the RPE scales were high for the Younger group (.90–.93) and moderate to high for the Older group (.56–.80). Regarding the validity of the RPE-color scale, the results appear to be much more consistent for the younger women than for the older ones. DISCUSSION The goal of this study was to develop a Color Scale of Perceived Exertion and validate it in groups of younger and older adult women. The results showed that for the younger adult women, the RPE-color scale was significantly associated with the physiological responses and had high correlations with the RPE-Borg scale. For the older adult women, the RPETABLE 4 LINEAR REGRESSION ANALYSIS BETWEEN RPE-COLOR SCALE WITH PHYSIOLOGICAL VARIABLES BY AGE GROUP Variable HR
V̇ O2
RPE-color Scale Reference
Younger Group Slope Intercept
r
Older Group 95%CI
Slope Intercept
r
95%CI
Overall
0.16
−14.45
.69* 0.10–0.22 0.14
−8.7
.39*
0.0–0.28
Legs
0.17
−14.94
.71* 0.11–0.22 0.13
−7.39
.39*
0.00–0.27
Chest
0.17
−15.22
.69* 0.10–0.23 0.14
−7.49
Overall
0.52
−2.01
.78* 0.38–0.67 0.25
7.95
.27
.41*
−0.10–0.61
0.02–0.26
Legs
0.59
−2.71
.85* 0.46–0.71 0.19
8.88
.22
−0.13–0.52
Chest 0.55 −2.06 .77* 0.39–0.71 0.28 6.58 .32 −0.05–0.61 Note.—HR = heart rate; V̇ O2 = oxygen consumption; CI = confidence interval; *p < .05.
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Chest
BIC
Legs
BIC
Overall
BIC
Chest
BIC
Legs
Borg
Color
575.3 573.2 577.8 403.9 404.4
1.1 (0.1)
14.7 (0.9) 14.5 (2.0) 1.0 (0.1)
378.1
12.1 (1.4) 9.7 (1.2)
389.3
13.0 (1.5) 12.0 (1.7) 1.1 (0.1)
581.8
141 (8.1) 123 (2.9) 2.1 (0.6)
577.6
133 (8.1) 123 (8.8) 2.7 (0.5)
579.5
117 (151) 1123 (7.7) 1.6 (4.1)
Color
0.8 (0.2)
1.2 (0.1)
1.1 (0.1)
3.0 (0.6)
3.2 (0.6)
3.2 (0.6)
Borg
Slope
Younger Group
Intercept
7.6*
11.8*
9.5*
3.6*
5.0*
4.8*
Color
t
5.0*
10.3*
9.1*
4.8*
5.7*
5.5*
Borg
Borg 356.9 359.1 357.6 298.6 298.6
Borg
0.2 (0.2)
0.4 (0.2)
0.8 (0.4)
0.6 (0.5)
1.1 (0.5)
19.4 (2.9) 22.3 (3.6) 0.2 (0.2) 0.02 (0.2)
297.0
17.5 (2.8) 19.2 (3.6) 0.3 (0.2)
298.6
19.9 (2.6) 16.2 (3.6) 0.2 (0.2)
353.8
138 (5.4) 143 (6.4) 1.0 (0.3)
351.7
134 (5.7) 135 (7.0) 1.3 (0.3)
352.8
141 (4.6) 12.5 (6.7) 0.9 (0.3)
Color
Slope Color
Older Group Intercept
1.2
1.8
1.1
3.1
3.9*
3.2*
Color
t
0.1
0.9
1.8
1.9
1.3
2.2*
Borg
BIC 400.7 413.9 298.2 298.9 Note.—HR = heart rate; V̇ O2 = oxygen consumption; BIC- Schwarz's Bayesian Criterion; Color = RPE-color scale; Borg = RPE-Borg; Parameter estimate (standard error of the estimate); *p < .05.
V̇ O2
Overall
HR
BIC
RPE Reference
Variable
TABLE 5 MULTILEVEL MIXED MODEL ANALYSIS FOR PHYSIOLOGICAL VARIABLES TO RPE-COLOR AND RPE-BORG SCALES BY AGE GROUP
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T. H. S. SERAFIM, ET AL. TABLE 6 LINEAR REGRESSION ANALYSIS BETWEEN RPE-COLOR AND RPE-BORG SCALES BY AGE GROUP
RPE Reference
Younger Group
Older Group
Slope
Intercept
r
95%CI
Slope
Intercept
r
95%CI
Overall
1.04
−1.60
.92*
.89–1.00
1.07
−2.05
.80*
.76–1.00
Legs
1.11
−2.59
.93*
.95–1.00
0.78
1.73
.56*
.33–1.00
Chest
1.05
−1.08
.90*
.88–1.00
0.95
−0.07
.68*
.56–1.00
Note.—CI = confidence interval; *p < .05.
color scale was significantly associated with HR and had moderate to high correlations with the RPE-Borg scale. Regarding the development of the RPE-color scale, men and women showed similar preferences for the arrangement of the colors. This finding is similar to other studies that showed no sex difference in color-emotion relations (Ou, et al., 2004). With respect to the association of colors, it was verified that the top of the scale comprised colors classified by the participants as light colors (e.g., lilac, yellow, and orange) and the bottom of the scale by dark colors (e.g., red, blue, and green). Lighter colors are more pleasant and less arousing than darker ones (Valdez & Mehrabian, 1994). Therefore, the participants may have related the lower exercise intensities of the scale with light colors that represent more pleasant emotions. Also, as the higher frequencies of colors chosen occurred at the extremes of the scale (7 and 19), it is possible to associate these colors with body temperature during the exercise. Indeed, the colors lilac and red were chosen to represent the lowest and highest intensities of exercise, respectively. According to Crozier (1996), the color violet is perceived as cold and the color red is perceived as warm. So, the participants may have associated the lowest and the highest exercise intensity with the body temperatures that these intensities generate. With regard to the frequencies of the colors chosen at each exertion level, there was notably less agreement for the choices of colors at RPEs 9, 11, and 13 (34%–41%). At higher exercise intensities, the exertion feelings are intensified (Noble & Robertson, 1996), and as a result participants may have had difficulty distinguishing the lower exercise intensities by associating them with different colors. A reduction of the number of the colors in the RPE-color scale (e.g., three colors) could be attempted to increase the consistency of colors associated with exertion. Although studies involving men are needed to generalize the RPEcolor scale to both sexes, the validation study of the RPE-color scale being performed using only women as participants was a reasonable preliminary assessment, since men and women did not differ in their reports during the RPE-color scale development. In this study, Robertson's (2004) rec-
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ommendations were followed because the RPE scale validation involves (a) being able to differentiate the RPE in different body parts that are involved during exercise; (b) being able to discriminate the diverse exercise intensities; and (c) being correlated with physiological responses. The RPE-color scale showed positive linear relation to HR and V̇ O2 in all body parts in the Younger group (Overall, Legs, and Chest). This result is similar to those found by Robertson, et al. (2004), who verified that RPE increased with the increment of exercise intensity for different body parts. For the Older group, the RPE-color scale for Overall and Legs showed positive linear functions only with HR. It was verified that the Older group had difficulty interpreting their perceived exertion using both RPE-Borg and RPE-color scales, corroborating a previous study (Andrade, et al., 2006). In addition, the short test duration of Older group (M = 9.6 min., SD = 3.0) may have reduced the linear relation between the RPE-color scale and V̇ O2, influencing the regression results. In accordance with significant positive linear relation between HR and V̇ O2 with both RPE scales in the Young group, high correlation values were found between the RPE-color scale and physiological responses in the current study (HR: r = .69–.71; V̇ O2: r = .77–.85). These results are in agreement with another study that showed correlations of .62 between RPE and HR (Morgan & Borg, 1976) and correlations of .84 and .76 between RPE and percentage of maximal HR and percentage of V̇ O2 max, respectively (Miyashita, Onodera, & Tabata, 1986, as cited in Borg, 1998). Concerning the Older group, the low correlations found in this study between the RPE-color scale and HR (.39–.41) and V̇ O2 (.22–.32) corroborate Miller, Bell, Collis, and Hoshizaki (1985), who found low correlations between RPE and HR in older men (.17–.25) and women (.43–.48) in walking exercise. However, these findings disagree with investigations that found moderate to high correlations (.63–.80) between RPE and physiological responses (HR and V̇ O2) in older adults (Bar-Or, Skinner, Buskirk, & Borg, 1972; Guidetti, Broccatelli, Baldari, Buzzachera, Goss, Utter, et al., 2011). As stated by Bar-Or (1977), the reduction of the observed correlation between RPE and HR occurs in response to aging and can be due to the lower range of possible HR values between resting and maximum HR, which occurs in parallel to the reduced work capacity. In fact, the range of the HR values was 53 beats/min. in the Older group, whereas in the Young group it was 109 beats/min. Moreover, intra- and intervariability of psychophysiological responses are greater in older adults compared to their younger counterparts (Spirduso, 1995). Normalizing the physiological responses to the respective maximal values could have increased the correlations and may constitute a suitable validation procedure in studies involving heterogeneous participants.
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The correlations between the RPE-color and RPE-Borg scales were high for the Younger group (.90–.93) and moderate to high for the Older adult group (.56–.80). These results agree with Robertson, et al. (2004), who showed correlations between the OMNI-RPE scale and RPE-Borg scale ranging from .92–.97 for the three body parts involved in exercise in adults. Furthermore, there were very high correlations (.96–.97) between the OMNI-RPE scale and the RPE-Borg scale in the elderly (Guidetti, Sgadari, et al., 2011). According to the magnitude thresholds of Hopkins, Marshall, Batterham, and Hanin (2009), the correlations of both age groups have adequate magnitude to ensure measures of validity. As the RPE-Borg represents the gold standard for RPE measures, the findings support the construct validity of the RPE-color scale for the assessment of RPE in treadmill exercise for adult women. Although the older adults belonged to physical activity programs, their physical activity varied considerably, which may explain the variance in metabolic equivalent spent during the exercise and the difficulty in reporting their exertion appropriately, especially at low workloads. The older participants tended to overestimate their perceived exertion at the beginning of the test on both RPE scales. Some studies have found that older adults overestimate RPE in the initial stages of exercise (Jasperse, Seals, & Callister, 1994; Allman & Rice, 2003; Pincivero, 2011). Therefore, the validity of relying on measures of perceived exertion from healthy older adults may be questionable (Pincivero, 2011). Moreover, as the capacity to perceive the sensations arising from the body decreases with aging (Khalsa, Rudrauf, & Tranel, 2009), the perception of effort during exercise may be misinterpreted by older people, exacerbated by possible problems in cognitive function or low educational level. These factors may have influenced the validation of the RPE-color scale in the Older adult group. The RPE-color scale is composed of seven colors associated with the seven different exercise intensities of the RPE-Borg scale. The use of colors may constitute a useful tool to assess perceived exertion by improving the perception of exercise-related feelings. The association of colors and exercise intensities of RPE scales can benefit the interpretation and assessment of perceived exertion. This issue is of particular importance when older people have to report their perceived exertion. Studies are needed to validate the RPE-color scale in special populations, such as individuals with low educational status or visual and cognitive impairments. Limitations and Conclusions This study has some limitations. Regarding the development process, no test-retest reliability of the RPE-color scale was performed, and for this reason further studies are needed to verify reliability of the scale. With regard to the validation process, the participants did not perform a familiar-
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ization session on the RPE scales and exercise on the treadmill. This may have hampered the appropriate assessment of effort and performance, especially for the older adult participants. Thus, conducting familiarization sessions with the RPE-color scale is necessary. Furthermore, the fact that participants performed only one experimental session to estimate perceived exertion on both RPE scales and the non-randomized order of RPE-Overall, Legs, and Chest may also have influenced the perceived exertion results. With respect to the age groups, the difference in the initial load of the incremental test may have exacerbated the difference in the psychophysiological responses between the participants. The RPE-color scale developed in this study has preliminary concurrent and construct validity for young adult women in treadmill exercise. Concerning the older adult women, the RPE-color scale has demonstrated construct validity, and further studies are needed to test the concurrent validity of the RPE-color scale in this population. Moreover, reliability and predictive validity studies of the RPE-color scale are required. REFERENCES
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DEVELOPMENT OF THE COLOR SCALE OF PERCEIVED EXERTION: PRELIMINARY VALIDATION1 THAIS H. S. SERAFIM AND ANDREA C. TOGNATO Department of Physical Education, São Paulo State University, Rio Claro, Brazil PRISCILA M. NAKAMURA Department of Physical Education, São Paulo State University, Rio Claro, Brazil Federal Institute of Education, Science and Technology South of Minas Gerais, Campus Muzambinho, Brazil MARCOS R. QUEIROGA
FÁBIO Y. NAKAMURA
Department of Physical Education Midwest State University UNICENTRO, Guarapuava, Brazil
Center of Physical Education and Sport State University of Londrina, Londrina, PR, Brazil
GLEBER PEREIRA
EDUARDO KOKUBUN
Núcleo de Ciências Biológicas e da Saúde, Universidade Positivo, Curitiba, Brazil Programa de Pós-Graduação em Educação Física, Universidade Federal do Paraná, Curitiba, Brazil
Department of Physical Education São Paulo State University, Rio Claro, Brazil
Summary.—This study developed a Color Scale of Perceived Exertion (RPEcolor scale) and assessed its concurrent and construct validity in adult women. One hundred participants (18–77 years), who were habitual exercisers, associated colors with verbal anchors of the Borg RPE scale (RPE-Borg scale) for RPE-color scale development. For RPE-color scale validation, 12 Young (M = 21.7 yr., SD = 1.5) and 10 Older (M = 60.3 yr., SD = 3.5) adult women performed a maximal graded exercise test on a treadmill and reported perceived exertion in both RPE-color and RPEBorg scales. In the Young group, the RPE-color scale was significantly associated with heart rate and oxygen consumption, having strong correlations with the RPEBorg scale. In the Older group, the RPE-color scale was significantly associated with heart rate, having moderate to high correlations with the RPE-Borg scale. The RPEcolor scale demonstrated concurrent and construct validity in the Young women, as well as construct validity in Older adults.
Perceived exertion is defined as the effort expended in performing a physical task (Marcora, 2009). To assess perceived exertion during aerobic exercise, several scales of perceived exertion have been developed (Borg, 1970; Robertson, Goss, Rutkowski, Lenz, Dixon, Timmer, et al., 2003; Persinger, Foster, Gibson, Fater, & Porcari, 2004; Borg & Kaijser, 2006; Borg, Address correspondence to Thais Helena Sayegh Serafim, Instituto de Biociências, Departamento de Educação Física, Universidade Estadual Paulista, Av. 24-A, n 1515, Bela Vista CEP: 13506-900, Rio Claro-SP, Brazil or e-mail ([email protected]). 1
DOI 10.2466/27.06.PMS.119c28z5
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2007) and have been used to prescribe and to monitor exercise intensity (Borg, 1982, 1990; Seiler & Kjerland, 2006). In addition, studies have demonstrated the effectiveness of the ratings of perceived exertion (RPE) scales in monitoring exercise intensity for both adults (Ceci & Hassmén, 1991; Robertson, Moyna, Sward, Millich, Goss, & Thompson, 2000; Karavatas & Tavakol, 2005) and the elderly (Dunbar & Kalinski, 2004; Shigematsu, Ueno, Nakagaichi, Nho, & Tanaka, 2004; Groslambert, Grange, Perrey, Maire, Tordi, & Rouillon, 2006). The Borg RPE scale (RPE-Borg scale) is the most commonly used to assess perceived exertion (Borg, 1998). It consists of 15 numerical descriptors with labels ranging from 6 to 20, as well as corresponding verbal descriptors. Borg RPE is correlated with heart rate (HR), oxygen consumption (V̇ O2), and blood lactate concentration in progressive exercise intensities during graded protocol tests (Borg, 1982; Robertson, Goss, & Metz, 1998; Chen, Fan, & Moe, 2002). Borg (1998) stated that the standard scale has some limitations, such as respondents' understanding and interpreting the ratings. For instance, changes in the verbal anchors' positioning and changes in the words may compromise understanding of perceived exertion and the interpretation of the scale in people who have low educational levels or visual or cognitive impairment. Therefore, other information in RPE scales should be provided to assist the evaluation of the perceived exertion. Some scales have used pictures associated with each workload, e.g., the OMNI-RPE scale (Robertson, Goss, Boer, Peoples, Foreman, Dabayebeh, et al., 2000; Nakamura, Perandini, Okuno, Borges, Bertuzzi, & Robertson, 2009; Guidetti, Sgadari, Buzzachera, Broccatelli, Utter, Goss, et al., 2011). However, these pictures can be difficult for those with visual or cognitive impairments. Thus, another type of visual resource might help such populations. Different colors can be associated with stress, since they are related to several emotional states and human perceptions regarding external clues (Crozier, 1996; Ou, Luo, Woodcock, & Wright, 2004; Gao & Xin, 2006; Carruthers, Morris, Tarrier, & Whorwell, 2010). It has been suggested that the origins of color vision among primates stems from the advantage it confers in being able to identify targets such as food against dappled or variegated backgrounds (Mollon, 1989). According to Akers, Barton, Cossey, Gainsford, Griffin, and Micklewright (2012), color perception in humans is associated with the survival instinct—for example, lower total mood disturbance and RPE was found during a cycling task performed with exposure to the color green compared to colors gray and red (Akers, et al., 2012). Furthermore, feelings of anger were heightened after the exposure to red compared to the other conditions. The use of colors can enhance the manner in which people perceive and recognize objects in the everyday world (Tanaka, Weiskopf, & Williams,
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2001). Colors have already been used in RPE scales for patients in rehabilitation (Trojan & Finch, 1997). However, that RPE scale used a small range of three colors. Given that colors can improve the perception of the environment and related situations, the use of colors to represent different exercise intensities in RPE scales may assist with the evaluation and interpretation of perceived exertion by improving the mapping of exercise-related feelings. Moreover, declines in cognitive function can affect the ability of an individual to assess the effort properly (Groslambert & Mahon, 2006). With aging, there is a reduction in cerebral blood flow that may lead to declining function (Ogoh & Ainslie, 2009). Therefore, older people may have difficulty using perception scales (Andrade, Pereira, & Sousa, 2006) that have numerical and verbal descriptors. The development and validation of a new RPE scale with colors is of particular significance for older people who may have difficulty using conventional perception scales. According to Robertson, Goss, Dubé, Rutkowski, Dupain, Brennan, et al. (2004), a valid RPE scale should be able to: (1) distinguish the perceived exertion related to different parts of the body involved in exercise (overall body, main skeletal muscles involved, and cardiorespiratory muscles); (2) distinguish the different exercise intensities; and (3) correlate with physiological responses. Therefore, the goal of the present study was to develop the RPE-color scale and to test its concurrent and construct validity in young adult and older adult women. Hypothesis 1. The RPE-color scale will significantly discriminate exercise intensities in different parts of the body involved during walking, i.e., exertion of the overall body, exertion in the legs, and exertion in the chest. Hypothesis 2. Scores on the RPE-color scale must be correlated positively with HR, V̇O2, and the RPE-Borg scale in the graded treadmill exercise test. Research Goal. Assess relations between the validity of the RPEcolor scale and age groups. METHOD Participants There were two samples in this study, one for the development of the RPE-color scale and another one for its validation. The Local Research Ethics Committee approved the study and all participants provided written informed consent. One hundred men (44%) and women (56%), ages 18 to 77 years (34% 18–40 years, 34% 41–60 years, and 33% 61–77 years), were interviewed. They were asked about the preferred color sequences for each exertion level. Par-
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ticipants were recruited from physical activity groups of SESI (Social Service of the Industry, Brazil), Health Units for Exercise, and students from São Paulo State University (Rio Claro-SP, Brazil). All the participants were habitual exercisers. For assessing the validity of the scale, 12 young adult women (Young sample; M age = 21.7 yr., SD = 1.5; M weight = 58.7 kg, SD = 7.8; M height = 161 cm, SD = 10.0) and 10 older adult women (Older group; M age = 60.3 yr., SD = 3.5; M weight = 69.5 kg, SD = 7.7; M height = 154 cm, SD = 10.0) were evaluated. The sample size was calculated considering α level of .05, power of .95, effect size of .90, and correlation coefficient of .85 (Lima, 2007). The required sample size calculated was 8 participants for each age group. Considering the possibility of losing 20% of the sample, a minimum of 10 participants for each group was included. All the participants were habitual exercisers and half of the older adults had low educational status, which means that they had studied until the middle school. Given that the sample of the development process of the scale included only adults, and the color preferences for the scale did not differ between sex (Table 2), only young adult women were included for the validation process as a matter of convenience. As older adults may have difficulty reporting perceived exertion, a preliminary testing of the RPE-color scale was performed to further validate it to such population use. RPE-color Scale Development For the RPE-color scale development, the seven colors of the rainbow were used as a reference because this is a well-known optical phenomenon. However, to offer a wider range of shades, the colors indigo and violet were replaced by the colors light blue and lilac, respectively. The standardization of the colors' shades was performed using the Red, Green, and Blue (RGB) scale. This scale has a range from 0: Darkest to 225: Lightest. Table 1 presents the tonality of the colors used in this study. TABLE 1 DESCRIPTION OF THE COLORS ACCORDING TO THE RED, GREEN, AND BLUE SCALE Colors
Red
Green
255
204
255
0
255
255
Yellow
255
255
0
Orange
0
Lilac Light blue
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Blue
255
153
Green
0
204
0
Blue
0
0
255
Red
255
0
0
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For data collection, a copy of the RPE-Borg scale (6–20) was used. Velcro® was attached next to the verbal anchors (6, 7, 9, 11, 13, 15, 17, 19, and 20) to make possible setting color strips on the RPE-Borg scale. Strips of the colors lilac, light blue, blue, green, yellow, orange, and red were made and attached with the other half of the Velcro® to allow participants to organize the order of the colors on the RPE-Borg scale according to their own association between color and perceived exertion. The numerical descriptors 8, 10, 12, 14, 16, and 18 represented transitions between intensity levels of the scale (Fig. 1). For the association of the color strips with the RPE-Borg scale, the participants received instructions about the scale and answered the following question: “Imagine that you are exercising. We would like you to estimate your perceived exertion, i.e., the effort expended in performing an exercise (e.g., light, heavy). It should take into account sensations of exertion on your body, your legs, and your breathing. Now examine this scale (RPE-Borg scale). We would like you to interpret it considering number 6 the white color, which corresponds to “no exertion at all,” and number 20 the black color, which corresponds to “maximal exertion.” The other numbers on the scale represent successive physical exertion levels, from the lightest to the heaviest effort. Then, we would like you to observe these strips in different colors and try to figure out what kind of sensation they bring to you. So, try to associate the strips with the different intensities of effort, placing them on the verbal anchors that best correspond to your sensations. Are there any questions?” RPE-color Scale Validation A day before the test, the participants were requested to not participate in vigorous activity and not to consume alcohol or caffeine, and have a good night of sleep. All participants attended the laboratory once and answered the Physical Activity Readiness Questionnaire (PAR-Q; American College of Sports Medicine, 2006). Subsequently, body mass (Welmy R-110, Santa Bárbara d'Oeste, Brazil), body height (WelmyR-110, Santa Bárbara d'Oeste, Brazil), heart rate at resting condition (Polar T31, Finland), and blood pressure (portable wrist monitor Bioland 3001, China) were measured. The participants were habituated to the treadmill (Inbramed Millennium ATL, Porto Alegre, Brazil) for 5 min., walking at 4 km·hr−1 (1% slope). The room temperature was kept constant at 25°C. After 10 minutes of rest, the experimental session was initiated. RPE-color scale for validation process.—The RPE-color scale did not include the numbers and the verbal anchors of the RPE-Borg scale. In addition, the RPE-color scale was shown to the participants in the opposite direction to the RPE-Borg scale: the white color corresponding to the verbal anchor “no exertion at all” at the bottom, and the black color correspond-
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ing to the verbal anchor “maximal exertion” at the top (Fig. 1, right panel). This approach was used to facilitate the visualization of the gradual increase of exercise intensities, i.e., the lowest value at the bottom, and the highest value at the top of the RPE-color scale. Ratings of perceived exertion.—During the incremental test, participants estimated the RPE for the overall body (RPE-Overall), for peripheral perceptions in the legs (RPE-Legs), and for respiratory-metabolic perceptions in the chest (RPE-Chest). First, participants estimated the perceived exertion on the RPE-color scale (Fig. 1, right panel) and afterward using the RPE-Borg scale. This order was fixed in all reports to ensure that ratings of the RPE-color scale would not be based on verbal anchors of the RPE-Borg scale. Instructions about the RPE scales.—Before the tests, the following instructions were given to participants: “These scales assess perceived exertion, i.e., the effort expended in performing an exercise (e.g., light, heavy). You should take into account sensations of exertion on your whole body, your legs, and your breathing. While you are walking, we will show you the color scale (RPE-color scale) first, and then we will show you the Borg scale (RPE-Borg scale). Now look at these scales. In the color scale, the white color (bottom) represents ‘no exertion at all’ and the black color (top) represents ‘maximal exertion.’ In the Borg RPE scale, the number 6 represents ‘no exertion at all’ and the number 20 represents ‘maximal exertion.’ We will ask you to point to colors (considering all colors of the RPE-color scale) and numbers (considering all numbers of the RPE-Borg scale) that express how you are feeling. We would like you to estimate your perceived exertion related to your whole body, your legs, and your chest. Remember that there is no right or wrong answer. Are there any questions?” Experimental protocol.—The participants performed an incremental treadmill test starting at 5.5 km.hr−1 and 6% or 2% slope for the Young and Older groups of adult women, respectively. Such different slopes could decrease the range of older adults' exercise test. Every 2 min., there were increments of 2% on the treadmill slope without changing the velocity. The criteria of the American College of Sports Medicine (2006) for test interruption were adopted and a physician observed the tests. In the last 30 sec. of each stage, heart rate and V̇ O2 (VO2000, Medical Graphics Corporation, St. Paul, USA) were recorded. The RPE in both scales were obtained in the second minute of each stage. Before all RPE estimations on the RPE-color scale, the information that the bottom and the top end of the scale corresponded to the verbal anchors “no exertion at all” and “maximal exertion,” respectively, was provided to the participants. Whereas the RPE-color scale comprised only the color gradient, it was necessary to associate the colors with the numbers of the RPE-Borg scale for analysis purposes. Thus, when the participants pointed to a color to
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estimate the RPE, a mark was made at the indicated site. Subsequently, transparent paper with the corresponding numbers of the RPE-Borg scale was placed over the RPE-color scale. Each RPE marking of the participant was assigned a number according to the RPE-Borg scale. The criterion for interruption of the test was volitional exhaustion for the Young group. For the Older group, 8 of the 10 interrupted the test at volitional exhaustion, while two participants interrupted the test at submaximal HR. After the end of the test, the participants remained in the laboratory for a few minutes and were examined by the physician. Data Analysis For the RPE-color scale development, a qualitative analysis of responses from the participants was performed. The frequency of color responses for each position of the RPE-Borg scale was analyzed for both sexes and for the total sample. The RPE-color scale was developed using the highest frequency color chosen by the total sample corresponding to each exertion level. For the RPE-color scale validation, the analyses were separated by age group. Descriptive data were calculated as means and standard deviations (SD). The concurrent validity was tested using linear regression analysis and linear mixed-model analysis. The linear regression analysis by the least squares method was performed for the RPE-color scale with the physiological variables. The linear mixed-model analysis, an extension of the general linear model, does not require observations to be independent with constant variance, so repeated-measures can be analyzed, and it allows for a large number of covariate structures, the inclusion of cases with incomplete data, and for data to be collected over time (Norusis, 2004). Therefore, data from all exercise stages performed by each participant were included in the analysis. The HR and V̇ O2 data were the dependent variables, and RPE-color ratings, RPE-Borg ratings, and exercise stages were defined as covariates. Moreover, RPE-color and RPE-Borg ratings were defined as fixed variables and the load as a random variable. Furthermore, the construct validity was tested using linear regression analysis by the least squares method between RPE-color and RPE-Borg scales. For all analyses, the significance level was set at p < .05 and the statistical functions of Microsoft Office Excel 2007 and STATISTICA 6.0 statistical package were used. RESULTS RPE-color Scale Development The RPE-color scale according to the sample's choices is presented in Fig. 1 (left panel). There was a high consistency between sexes for the color preferences at each level of perceived exertion (Table 2).
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FIG. 1. Color Scale of Perceived Exertion (RPE-color scale) developed in this study (left panel) and RPE-color scale as validated (right panel).
RPE-color Scale Validation The descriptive data from the incremental test by age group is shown in Table 3. Table 4 presents the analysis for testing the concurrent validity of the RPE-color scale. There were high correlations between the RPEcolor scale and HR (.69–.71) and V̇ O2 (.77–.85) for the Younger group. For the Older group, there were weak correlations between the RPE-color scale and HR (.39–.41) and V̇ O2 (.22–.32). Table 5 presents the multilevel mixed model analysis for the physiological variables to the RPE-color and RPE-Borg scales by age group. For the Younger group, the RPEs from both scales were significant (p < .05) positive linear functions of HR and V̇ O2. For the Older group, RPE-Overall from both scales and RPE-Legs from the RPE-color scale were significant (p < .05) positive linear functions of HR. TABLE 2 HIGHEST FREQUENCIES (%) OF COLOR ASSIGNMENTS TO EACH EXERTION LEVEL OF RPE-BORG SCALE BY SEX Exertion
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Color
Men (n = 44)
Women (n = 56)
Total (N = 100)
7
Lilac
70
64
67
9
Yellow
41
39
40
11
Orange
41
34
37
13
Light blue
39
36
37
15
Green
36
45
41
17
Blue
43
46
45
19
Red
75
70
72
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T. H. S. SERAFIM, ET AL. TABLE 3 DESCRIPTIVE STATISTICS BY TREADMILL SLOPE FOR RPE AND PHYSIOLOGICAL VARIABLES Younger Group Variable
M
SD
Min.
Slope (%)
11.8
4.5
RPE-Overall (Color)
11.7
RPE-Overall (Borg) RPE-Legs (Color)
Older Group Max.
M
SD
Min.
6
24
6.1
3.4
2
14
4.1
6
20
11.8
4.9
6
20
12.9
3.8
6
20
13.6
3.6
6
20
12.8
4.3
6
20
11.6
4.4
6
20
RPE-Legs (Borg)
13.9
3.8
7
20
13.7
3.3
6
20
RPE-Chest (Color)
12.3
4.3
6
20
11.8
4.5
6
20
RPE-Chest (Borg)
13.0
3.9
6
20
166 HR (beats·min.−1) −1 −1 ̇ VO2 (ml·kg ·min. ) 27.2
22.2
98
207
13.2 143
Max.
3.1
6
20
13.3
115
168
6.0 16.4 38.9 20.7 6.4 10.4 47.1 Note.—Color = RPE-color scale; Borg = RPE-Borg; HR = heart rate; V̇ O2 = oxygen consumption.
The analysis for testing the construct validity of the RPE-color scale is shown in Table 6. The correlations between the RPE scales were high for the Younger group (.90–.93) and moderate to high for the Older group (.56–.80). Regarding the validity of the RPE-color scale, the results appear to be much more consistent for the younger women than for the older ones. DISCUSSION The goal of this study was to develop a Color Scale of Perceived Exertion and validate it in groups of younger and older adult women. The results showed that for the younger adult women, the RPE-color scale was significantly associated with the physiological responses and had high correlations with the RPE-Borg scale. For the older adult women, the RPETABLE 4 LINEAR REGRESSION ANALYSIS BETWEEN RPE-COLOR SCALE WITH PHYSIOLOGICAL VARIABLES BY AGE GROUP Variable HR
V̇ O2
RPE-color Scale Reference
Younger Group Slope Intercept
r
Older Group 95%CI
Slope Intercept
r
95%CI
Overall
0.16
−14.45
.69* 0.10–0.22 0.14
−8.7
.39*
0.0–0.28
Legs
0.17
−14.94
.71* 0.11–0.22 0.13
−7.39
.39*
0.00–0.27
Chest
0.17
−15.22
.69* 0.10–0.23 0.14
−7.49
Overall
0.52
−2.01
.78* 0.38–0.67 0.25
7.95
.27
.41*
−0.10–0.61
0.02–0.26
Legs
0.59
−2.71
.85* 0.46–0.71 0.19
8.88
.22
−0.13–0.52
Chest 0.55 −2.06 .77* 0.39–0.71 0.28 6.58 .32 −0.05–0.61 Note.—HR = heart rate; V̇ O2 = oxygen consumption; CI = confidence interval; *p < .05.
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Chest
BIC
Legs
BIC
Overall
BIC
Chest
BIC
Legs
Borg
Color
575.3 573.2 577.8 403.9 404.4
1.1 (0.1)
14.7 (0.9) 14.5 (2.0) 1.0 (0.1)
378.1
12.1 (1.4) 9.7 (1.2)
389.3
13.0 (1.5) 12.0 (1.7) 1.1 (0.1)
581.8
141 (8.1) 123 (2.9) 2.1 (0.6)
577.6
133 (8.1) 123 (8.8) 2.7 (0.5)
579.5
117 (151) 1123 (7.7) 1.6 (4.1)
Color
0.8 (0.2)
1.2 (0.1)
1.1 (0.1)
3.0 (0.6)
3.2 (0.6)
3.2 (0.6)
Borg
Slope
Younger Group
Intercept
7.6*
11.8*
9.5*
3.6*
5.0*
4.8*
Color
t
5.0*
10.3*
9.1*
4.8*
5.7*
5.5*
Borg
Borg 356.9 359.1 357.6 298.6 298.6
Borg
0.2 (0.2)
0.4 (0.2)
0.8 (0.4)
0.6 (0.5)
1.1 (0.5)
19.4 (2.9) 22.3 (3.6) 0.2 (0.2) 0.02 (0.2)
297.0
17.5 (2.8) 19.2 (3.6) 0.3 (0.2)
298.6
19.9 (2.6) 16.2 (3.6) 0.2 (0.2)
353.8
138 (5.4) 143 (6.4) 1.0 (0.3)
351.7
134 (5.7) 135 (7.0) 1.3 (0.3)
352.8
141 (4.6) 12.5 (6.7) 0.9 (0.3)
Color
Slope Color
Older Group Intercept
1.2
1.8
1.1
3.1
3.9*
3.2*
Color
t
0.1
0.9
1.8
1.9
1.3
2.2*
Borg
BIC 400.7 413.9 298.2 298.9 Note.—HR = heart rate; V̇ O2 = oxygen consumption; BIC- Schwarz's Bayesian Criterion; Color = RPE-color scale; Borg = RPE-Borg; Parameter estimate (standard error of the estimate); *p < .05.
V̇ O2
Overall
HR
BIC
RPE Reference
Variable
TABLE 5 MULTILEVEL MIXED MODEL ANALYSIS FOR PHYSIOLOGICAL VARIABLES TO RPE-COLOR AND RPE-BORG SCALES BY AGE GROUP
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T. H. S. SERAFIM, ET AL. TABLE 6 LINEAR REGRESSION ANALYSIS BETWEEN RPE-COLOR AND RPE-BORG SCALES BY AGE GROUP
RPE Reference
Younger Group
Older Group
Slope
Intercept
r
95%CI
Slope
Intercept
r
95%CI
Overall
1.04
−1.60
.92*
.89–1.00
1.07
−2.05
.80*
.76–1.00
Legs
1.11
−2.59
.93*
.95–1.00
0.78
1.73
.56*
.33–1.00
Chest
1.05
−1.08
.90*
.88–1.00
0.95
−0.07
.68*
.56–1.00
Note.—CI = confidence interval; *p < .05.
color scale was significantly associated with HR and had moderate to high correlations with the RPE-Borg scale. Regarding the development of the RPE-color scale, men and women showed similar preferences for the arrangement of the colors. This finding is similar to other studies that showed no sex difference in color-emotion relations (Ou, et al., 2004). With respect to the association of colors, it was verified that the top of the scale comprised colors classified by the participants as light colors (e.g., lilac, yellow, and orange) and the bottom of the scale by dark colors (e.g., red, blue, and green). Lighter colors are more pleasant and less arousing than darker ones (Valdez & Mehrabian, 1994). Therefore, the participants may have related the lower exercise intensities of the scale with light colors that represent more pleasant emotions. Also, as the higher frequencies of colors chosen occurred at the extremes of the scale (7 and 19), it is possible to associate these colors with body temperature during the exercise. Indeed, the colors lilac and red were chosen to represent the lowest and highest intensities of exercise, respectively. According to Crozier (1996), the color violet is perceived as cold and the color red is perceived as warm. So, the participants may have associated the lowest and the highest exercise intensity with the body temperatures that these intensities generate. With regard to the frequencies of the colors chosen at each exertion level, there was notably less agreement for the choices of colors at RPEs 9, 11, and 13 (34%–41%). At higher exercise intensities, the exertion feelings are intensified (Noble & Robertson, 1996), and as a result participants may have had difficulty distinguishing the lower exercise intensities by associating them with different colors. A reduction of the number of the colors in the RPE-color scale (e.g., three colors) could be attempted to increase the consistency of colors associated with exertion. Although studies involving men are needed to generalize the RPEcolor scale to both sexes, the validation study of the RPE-color scale being performed using only women as participants was a reasonable preliminary assessment, since men and women did not differ in their reports during the RPE-color scale development. In this study, Robertson's (2004) rec-
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ommendations were followed because the RPE scale validation involves (a) being able to differentiate the RPE in different body parts that are involved during exercise; (b) being able to discriminate the diverse exercise intensities; and (c) being correlated with physiological responses. The RPE-color scale showed positive linear relation to HR and V̇ O2 in all body parts in the Younger group (Overall, Legs, and Chest). This result is similar to those found by Robertson, et al. (2004), who verified that RPE increased with the increment of exercise intensity for different body parts. For the Older group, the RPE-color scale for Overall and Legs showed positive linear functions only with HR. It was verified that the Older group had difficulty interpreting their perceived exertion using both RPE-Borg and RPE-color scales, corroborating a previous study (Andrade, et al., 2006). In addition, the short test duration of Older group (M = 9.6 min., SD = 3.0) may have reduced the linear relation between the RPE-color scale and V̇ O2, influencing the regression results. In accordance with significant positive linear relation between HR and V̇ O2 with both RPE scales in the Young group, high correlation values were found between the RPE-color scale and physiological responses in the current study (HR: r = .69–.71; V̇ O2: r = .77–.85). These results are in agreement with another study that showed correlations of .62 between RPE and HR (Morgan & Borg, 1976) and correlations of .84 and .76 between RPE and percentage of maximal HR and percentage of V̇ O2 max, respectively (Miyashita, Onodera, & Tabata, 1986, as cited in Borg, 1998). Concerning the Older group, the low correlations found in this study between the RPE-color scale and HR (.39–.41) and V̇ O2 (.22–.32) corroborate Miller, Bell, Collis, and Hoshizaki (1985), who found low correlations between RPE and HR in older men (.17–.25) and women (.43–.48) in walking exercise. However, these findings disagree with investigations that found moderate to high correlations (.63–.80) between RPE and physiological responses (HR and V̇ O2) in older adults (Bar-Or, Skinner, Buskirk, & Borg, 1972; Guidetti, Broccatelli, Baldari, Buzzachera, Goss, Utter, et al., 2011). As stated by Bar-Or (1977), the reduction of the observed correlation between RPE and HR occurs in response to aging and can be due to the lower range of possible HR values between resting and maximum HR, which occurs in parallel to the reduced work capacity. In fact, the range of the HR values was 53 beats/min. in the Older group, whereas in the Young group it was 109 beats/min. Moreover, intra- and intervariability of psychophysiological responses are greater in older adults compared to their younger counterparts (Spirduso, 1995). Normalizing the physiological responses to the respective maximal values could have increased the correlations and may constitute a suitable validation procedure in studies involving heterogeneous participants.
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The correlations between the RPE-color and RPE-Borg scales were high for the Younger group (.90–.93) and moderate to high for the Older adult group (.56–.80). These results agree with Robertson, et al. (2004), who showed correlations between the OMNI-RPE scale and RPE-Borg scale ranging from .92–.97 for the three body parts involved in exercise in adults. Furthermore, there were very high correlations (.96–.97) between the OMNI-RPE scale and the RPE-Borg scale in the elderly (Guidetti, Sgadari, et al., 2011). According to the magnitude thresholds of Hopkins, Marshall, Batterham, and Hanin (2009), the correlations of both age groups have adequate magnitude to ensure measures of validity. As the RPE-Borg represents the gold standard for RPE measures, the findings support the construct validity of the RPE-color scale for the assessment of RPE in treadmill exercise for adult women. Although the older adults belonged to physical activity programs, their physical activity varied considerably, which may explain the variance in metabolic equivalent spent during the exercise and the difficulty in reporting their exertion appropriately, especially at low workloads. The older participants tended to overestimate their perceived exertion at the beginning of the test on both RPE scales. Some studies have found that older adults overestimate RPE in the initial stages of exercise (Jasperse, Seals, & Callister, 1994; Allman & Rice, 2003; Pincivero, 2011). Therefore, the validity of relying on measures of perceived exertion from healthy older adults may be questionable (Pincivero, 2011). Moreover, as the capacity to perceive the sensations arising from the body decreases with aging (Khalsa, Rudrauf, & Tranel, 2009), the perception of effort during exercise may be misinterpreted by older people, exacerbated by possible problems in cognitive function or low educational level. These factors may have influenced the validation of the RPE-color scale in the Older adult group. The RPE-color scale is composed of seven colors associated with the seven different exercise intensities of the RPE-Borg scale. The use of colors may constitute a useful tool to assess perceived exertion by improving the perception of exercise-related feelings. The association of colors and exercise intensities of RPE scales can benefit the interpretation and assessment of perceived exertion. This issue is of particular importance when older people have to report their perceived exertion. Studies are needed to validate the RPE-color scale in special populations, such as individuals with low educational status or visual and cognitive impairments. Limitations and Conclusions This study has some limitations. Regarding the development process, no test-retest reliability of the RPE-color scale was performed, and for this reason further studies are needed to verify reliability of the scale. With regard to the validation process, the participants did not perform a familiar-
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ization session on the RPE scales and exercise on the treadmill. This may have hampered the appropriate assessment of effort and performance, especially for the older adult participants. Thus, conducting familiarization sessions with the RPE-color scale is necessary. Furthermore, the fact that participants performed only one experimental session to estimate perceived exertion on both RPE scales and the non-randomized order of RPE-Overall, Legs, and Chest may also have influenced the perceived exertion results. With respect to the age groups, the difference in the initial load of the incremental test may have exacerbated the difference in the psychophysiological responses between the participants. The RPE-color scale developed in this study has preliminary concurrent and construct validity for young adult women in treadmill exercise. Concerning the older adult women, the RPE-color scale has demonstrated construct validity, and further studies are needed to test the concurrent validity of the RPE-color scale in this population. Moreover, reliability and predictive validity studies of the RPE-color scale are required. REFERENCES
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