OMNI scale perceived exertion at ventilatory breakpoint in children ...

Psychobiology and Social Sciences
OMNI scale perceived exertion at ventilatory
breakpoint in children: response normalized
ROBERT J. ROBERTSON, FREDRIC L. GOSS, NICHOLAS BOER, JERE D. GALLAGHER, TAYLOR THOMPKINS,
KAREN BUFALINO, G. BALASEKARAN, CHERIE MECKES, JENNIFER PINTAR, and ALLISON WILLIAMS
Center for Exercise and Health-Fitness Research, Department of Health and Physical Education, University of Pittsburgh,
Pittsburgh, PA 15261
ABSTRACT
ROBERTSON, R. J., F. L. GOSS, N. BOER, J. D. GALLAGHER, T. THOMPKINS, K. BUFALINO, G. BALASEKARAN, C.
MECKES, J. PINTAR, and A. WILLIAMS. OMNI scale perceived exertion at ventilatory breakpoint in children: response normalized.
Med. Sci. Sports Exerc., Vol. 33, No. 11, 2001, pp. 1946–1952. Purpose: The Children’s OMNI Scale of Perceived Exertion was used
to identify a response normalized rating of perceived exertion (RPE)-Overall, RPE-Legs, and RPE-Chest that corresponds to the
ventilatory breakpoint (Vpt) in 8- to 12-yr-old female and male children. Methods: Subjects were a priori stratified into two fitness
groups on the basis of peak oxygen uptake (V˙ O2peak): average (A) (41.0–49.0 mL·kg �1 ·min �1 ; N � 24) and above average (AA)
(50.0–58.0 mL·kg �1 ·min �1 ; N � 24). Vpt was determined by a progressive cycle ergometer protocol to V˙ O2peak. Results: A gender
effect was not observed for any descriptive or dependent variable. Mean V˙ O2peak for the A group was 1.72 L·min �1 and for the AA
group 2.04 L·min �1 . Vpt corresponded to 64.0% V˙ O2peak for A and 74.0% V˙ O2peak for AA. RPE-Overall (mean A and AA, 6.1),
RPE-Legs (mean A and AA, 7.2), and RPE-Chest (mean A and AA, 4.5) did not differ between the fitness groups. Conclusion:
Findings indicated that undifferentiated and differentiated RPE-Vpt were similar between female and male children who varied in
V˙ O2peak and Vpt. A comparatively stable RPE-Vpt for 8- to 12-yr-old children that vary in V˙ O2peak and Vpt indicates a group
normalized perceptual response. Key Words: DIFFERENTIATED RPE, UNDIFFERENTIATED RPE, PEDIATRIC SUBJECTS
This investigation used the newly developed Children’s
OMNI Scale of Perceived Exertion (22) to
determine undifferentiated and differentiated ratings
of perceived exertion (RPE) at the ventilatory breakpoint
(Vpt) for pediatric subjects that varied in peak oxygen
uptake (V˙ O 2peak). The undifferentiated RPE was assessed
for the overall body (RPE-Overall), whereas the differentiated
RPE was anatomically regionalized to the legs (RPE-
Legs) and chest (RPE-Chest). The Children’s OMNI Scale
has a pictorial-verbal-numerical format with categories arranged
along a response continuum from 0 to 10 (Fig. 1).
The scale contains six verbal descriptors positioned according
to ascending order of semantic intensity: “not at all
tired,” “a little tired,” “getting more tired,” “tired,” “really
tired,” and “very, very tired.” Concurrent validity coefficients
for the interrelations between OMNI Scale RPE-
Overall, RPE-Legs, and RPE-Chest and both oxygen uptake
and heart rate during cycle ergometer exercise range from
r � 0.85 to r � 0.94 in clinically normal African-American
and Caucasian-American children, 8 to 12 yr of age (22). Of
practical importance in developing this scale was the
0195-9131/01/3311-1946/$3.00/0
MEDICINE & SCIENCE IN SPORTS & EXERCISE ®
Copyright © 2001 by the American College of Sports Medicine
Submitted for publication July 2000.
Accepted for publication February 2001.
1946
expectation that a single format could be used with female
and male children having multiracial origins; hence the
name OMNI Scale. The term OMNI is a contemporary
contraction of the word omnibus, i.e., a scale with broadly
encompassing properties.
The Vpt has been used to prescribe exercise intensity,
predict endurance performance, compartmentalize aerobic/
anaerobic energy metabolism, and diagnose clinical status in
adults that vary in aerobic fitness and training status (4–
6,12,19,29,30). Although somewhat more limited in scope,
similar applications of the Vpt have been used in pediatric
groups (7,12–15,19,20,26,28). Given the utility of the Vpt,
a practical, noninvasive procedure to identify the physiological
and physical markers of this methodological construct
would be useful. The identification of a stable RPE
that corresponds to the Vpt may be the basis for this noninvasive
procedure. A number of previous investigations
involving adults reported that the RPE corresponding to the
Vpt (RPE-Vpt) and/or lactate inflection point ranged from a
rating of 11 to 14 on the 15-category Borg Perceived Exertion
Scale (3,6,8–11,15,18,24). In these investigations, the
RPE response range that spanned the Vpt was stable for
females and males who varied in aerobic fitness and endurance
training status and was generally independent of exercise
mode. A comparatively stable RPE at the Vpt and/or
lactate inflection point can be characterized as a response
normalized perceptual measurement. Response normalized

FIGURE 1—Children’s OMNI Scale of Perceived Exertion (22).
modeling identifies either a stable RPE or RPE range that (a)
corresponds to an exercise intensity that produces a prescribed
physiological and/or psychological outcome and (b)
is common to a specified and defined individual and/or
group (23).
A comparatively stable RPE-Vpt has been observed for
selected pediatric subsets where assessments were made
with the Borg 15-category scale (7,14,15). The stability of
this perceptual response may be practical when identifying
the Vpt in young children where the respiratory-metabolic
measurement procedures typically used in the assessment
can be problematic. In previous investigations involving
pediatric samples, the RPE-Overall corresponding to the
Vpt ranged from 11 to 14 in female and male children 8 to
12 yr of age. Determination of a differentiated RPE (i.e.,
Legs and Chest) that is consonant with the Vpt in children
has been undertaken in only one previous investigation.
Mahon et al. (15) reported that RPE-Legs and RPE-Chest at
the Vpt during cycle ergometer exercise were 14.1 and 12.6,
respectively, in children having a mean age of 10.9 yr.
The present experiment used the Children’s OMNI Scale
of Perceived Exertion to identify a response normalized
RPE-Overall, RPE-Legs, and RPE-Chest that corresponds
to the Vpt in 8- to 12-yr-old female and male children
having a V˙ O 2peak ranging from 41.0 to 58.0 mL·kg �1 ·min �1
and a Vpt ranging from 64.0 to 74.0% V˙ O 2peak. A substantial
number of investigations using adult samples have demonstrated
that the RPE corresponding to either the Vpt or
lactate inflection point was not affected by gender, training
status, exercise modality, or training specificity
(3,6,9,11,18,24). The experimental paradigms used in these
investigations postulated that the metabolic and/or physical
intensities equivalent to either the Vpt or lactate inflection
point would vary with a given independent variable (i.e.,
aerobic fitness, training status, and exercise modality),
whereas the RPE range corresponding to the breakpoint
would be invariant. A conceptually similar paradigm was
used presently where the RPE-Vpt was compared between
groups of children that had been a priori stratified by a
single independent variable, i.e., V˙ O 2peak. The paradigm
assumed that the Vpt varied directly with V˙ O 2peak, i.e., Vpt
would occur at a higher V˙ O 2 in the group having the
comparatively higher than lower V˙ O 2peak (13,19,30). However,
it was expected that the RPE-Vpt determined by the
OMNI Scale would not differ between groups of female and
male children who varied in V˙ O 2peak and as such their Vpt.
A comparatively stable RPE-Vpt for 8- to 12-yr-old female
and male children who vary in their V˙ O 2peak and Vpt would
be indicative of a normalized perceptual response.
METHODS
Subjects. Forty-eight clinically normal, nonobese African-American
and Caucasian-American female and male
children ranging in age from 8 to 12 yr participated as
subjects. Their descriptive characteristics are presented in
Table 1. Sample size was determined for the statistical
power required to demonstrate an interaction effect within
the repeated measures comparisons of RPE-Vpt (25). This
power requirement was the most stringent among any of the
statistical models used and as such required the greatest
number of subjects for each contrast cell. Using a power of
0.80, an � level of 0.05, and an effect size of � 1.1, it was
determined that nine children were required in each of the
four gender � fitness groups in order to test both the main
and interaction effects. The within-subject factor in the
power calculation assumed an intraclass correlation of r �
0. 80 over the repeated measures. The power calculation was
derived from a previous report by Robertson et al. (22)
where RPE was derived using the Children’s OMNI Scale.
The total sample was divided into two fitness groups, each
having 12 female African-American, 12 female Caucasian-
American, 12 male African-American, and 12 male Caucasian-American
children. Group assignment was determined
on the basis of measured cycle ergometer peak oxygen
uptake indexed to total body weight (V˙ O 2peak)
(mL·kg �1 ·min �1 ). Subjects who had a V˙ O 2peak between
41.0 and 49.0 mL·kg �1 ·min �1 were assigned to the “average”
(A) aerobic fitness group and those who had a V˙ O 2peak
between 50.0 and 58.0 mL·kg �1 ·min �1 were assigned to the
“above average” (AA) aerobic fitness group.
Subjects were volunteers who demonstrated sufficient
cognitive ability to read out loud each verbal descriptor on
the Children’s OMNI Scale. Medical clearance to undertake
exercise testing was required before participation. Risks and
benefits were explained and the subject and his/her parent/
guardian gave their written consent to participate. Subjects
did not have cardiovascular, neuromotor, or cognitive contraindications
to exercise testing as determined during the
preparticipation medical examination. The experimental
protocol to use children as research subjects was approved
by the University of Pittsburgh Institutional Review Board.
Experimental design and test sessions. The investigation
used a cross-sectional experimental design consisting
of two laboratory testing sessions separated by a minimum
of 48 h and maximum of 72 h. During the first session,
subjects were familiarized with cycle ergometer exercise
testing and use of the Children’s OMNI Scale of Perceived
Exertion. The cycle familiarization procedures consisted of
three 3-min power output stages (25, 50, and 75 W) presented
continuously in ascending order of intensity. Particular
attention was directed to proper pedaling cadence. A
respiratory valve/mouthpiece and heart rate monitor were
RPE AT VENTILATORY BREAKPOINT Medicine & Science in Sports & Exercise � 1947

TABLE 1. Descriptive characteristics of 8- to 12-yr-old female and male subjects.
V˙O 2peak
Age (yr) Ht (cm) Wt (kg)
(mL�kg
Fitness
–1�min –1 )
M � SD M � SD M � SD M � SD
A-Female 10.0 � 1.3 143.3 � 7.5 38.0 � 2.3 44.6 � 3.0
A-Male 9.8 � 1.6 142.6 � 7.6 38.0 � 2.1 45.0 � 2.6
AA-Female 10.3 � 1.4 144.0 � 9.6 37.4 � 2.0 54.4 � 2.2
AA-Male 10.0 � 1.7 143.3 � 9.9 37.3 � 1.7 54.5 � 2.3
Source
F
positioned on the subject during the orientation session.
Subjects were instructed regarding the use of the Children’s
OMNI Scale before the cycle orientation and practiced
rating their RPE-Overall, RPE-Legs, and RPE-Chest during
each exercise stage. At the beginning of the orientation
session, body weight (kg) and height (cm) were determined
with a Detect-Medic Scale and attached stadiometer (Detecto
Scales, Inc., Brooklyn, NY).
The second session consisted of a perceptual estimation
exercise test administered on a Monark (Model 864, Sweden)
cycle ergometer equipped with a plate-loading system
to apply brake force. A progressive multistage test protocol
was used. The initial brake resistance was 25 W and was
incremented by 10 W at the beginning of each 3-min test
stage. Test termination was defined as the inability to maintain
the designated pedal rate for 15 consecutive seconds
owing to exhaustion. A pedal rate of 50 rpm signaled by an
electronic metronome was used for the entire test protocol.
Ventilatory breakpoint. The Vpt was identified using
respiratory-gas exchange measurements obtained every 15 s
during the multistage cycle exercise test. The ventilatory
equivalents for oxygen (V˙ E:V˙ O 2) and carbon dioxide (V˙ E:
V˙ CO 2) were plotted as a function of V˙ O 2. The measurement
criterion for the Vpt was taken as the V˙ O 2 at which V˙ E:V˙ O 2
increased without a concomitant increase in V˙ E:V˙ CO 2
(4,15,28). The Vpt was detectable from individual plots for
each subject and was expressed in both absolute (L·min �1 )
and relative (%V˙ O 2peak) units.
Cardiorespiratory and Aerobic Metabolic
Measures
Heart rate (HR) (beats·min �1 ) was measured from 45 to
60 s during each minute of exercise using a Polar monitoring
system (Polar Electro, Finland). Respiratory-metabolic and
gas exchange variables were measured with an automated
open circuit indirect calorimetric system (MedGraphics,
Inc., St. Paul, MN). Oxygen uptake (V˙ O2)(L·min �1 ), carbon
dioxide production (V˙ CO2)(L·min �1 ), and respiratory
flow (V˙ E) (L·min �1 ) were determined every 15 s and expressed
as STPD. A standard respiratory valve (Model
2700; Hans Rudolph, Kansas City, MO) with a child-size
Age Ht Wt V˙O 2peak
P
Value F
P
Value F
P
Value F
Gender 0.45 0.50 0.08 0.78 0.01 0.94 0.08 0.78
Fitness 0.45 0.50 0.08 0.78 1.10 0.29 174.20 0.01*
Gender � fitness 0.01 0.92 0.01 0.99 0.01 0.94 0.08 0.78
Ht, height; Wt, weight; V˙ O2peak, peak oxygen uptake; A, average fitness; AA, above average fitness.
Data are means (M) � standard deviation (SD); df: gender � 1, fitness � 1, gender � fitness � 1, error � 44.
* Significant.
P
Value
mouthpiece was used for all respiratory-metabolic measurements.
V˙ O 2peak was taken as the highest 60-s value recorded
during the final stage of the cycle exercise protocol. Confirming
criteria included attainment of � 5 beats·min �1 of
the age-predicted peak value for the subjects studied (i.e.,
195 beats·min �1 ) and a respiratory exchange ratio (RER) �
1.1.
Ratings of Perceived Exertion
The Children’s OMNI Sale was used to estimate three
separate RPE between 30 and 60 s of each minute of
exercise. An undifferentiated rating was estimated for the
overall body (RPE-Overall) and a differentiated rating was
estimated for peripheral perceptions of exertion in the legs
(RPE-Legs) and respiratory-metabolic perceptions in the
chest (RPE-Chest). A definition of perceived exertion specifically
developed for children and a standard set of instructions
regarding use of the OMNI Scale to rate perceptions
of exertion were read to the subject immediately before
the exercise test (22), as follows:
Definition: How “tired” does your body feel during
exercise?
Instructions: We would like you to ride on the bicycle for a
little while. Every few minutes it will get harder to pedal
the bicycle. Please use the numbers on this picture to tell
us how your body feels when bicycling. Please look at the
person at the bottom of the hill who is just starting to ride
a bicycle (point to left pictorial). If you feel like this
person when you are riding you will be “not tired at all.”
You should point to a 0. Now look at the person who is
barely able to ride a bicycle to the top of the hill (point to
the right pictorial). If you feel like this person when riding
you will be “very, very tired.” You should point to a
number 10. If you feel somewhere in between “not tired
at all” (0) and “very, very tired” (10), then point to a
number between 0 and 10.
We will ask you to point to a number that tells how your
whole body feels, then a number that tells how your legs
feel, and then a number that tells how your breathing
feels. Remember, there are no right or wrong numbers.
1948 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org

Use both the pictures and words to help select the numbers.
Use any of the numbers to tell how you feel when
riding the bicycle.
The low and high perceptual anchors for the OMNI Scale
were established using the procedure reported previously by
Robertson et al. (22). This procedure requires the subject to
cognitively establish a perceived intensity of exertion that is
consonant with that depicted visually by the cyclist at the
bottom (i.e., low anchor, rating 0) and top (i.e., high anchor,
rating 10) of the hill as presented in the OMNI Scale
illustrations. Subjects were instructed to rate using whole
numbers only. The rating was repeated to the subject to
confirm its accuracy. The OMNI Scale was in full view of
the subject at all times during testing. As a respiratory valve
prohibited a verbal rating response, subjects pointed to their
RPE on the OMNI Scale.
Data analysis. Age, height, and weight were calculated
as means � standard deviations (SD) and reported separately
for female and male children within the two fitness
groups. Descriptive data were compared using a two-factor
(gender � fitness) analysis of variance (ANOVA). The
physiological responses at peak exercise (i.e., V˙ O 2, HR, and
RER) and at the Vpt (i.e., %V˙ O 2peak, V˙ O 2, and HR) during
the cycle ergometer test were also compared using a gender
� fitness ANOVA. RPE-Overall, RPE-Legs, and RPE-
Chest determined at peak exercise and at the Vpt during the
cycle ergometer test were examined by a three-factor (RPE
� gender � fitness) ANOVA with repeated measures on the
first factor. Significant main and interaction effects were
analyzed with a simple effects post hoc procedure. All
analyses were performed using an SPSS for Windows 8.0
(1997) statistical package (SPSS, Inc., Chicago, IL).
RESULTS
Descriptive characteristics. The descriptive characteristics
of the female and male subjects in the two fitness
groups are presented in Table 1. Neither the gender and
fitness main effects nor the gender � fitness interaction
effect were significant for age, height, and weight, indicating
that these descriptive variables did not differ between
the four experimental groupings. The fitness main effect for
V˙ O 2peak (mL·kg �1 ·min �1 ) was significant (P � 0.01),
whereas the gender main effect and gender � fitness interaction
effect were not significant. As such, V˙ O 2peak
(mL·kg �1 ·min �1 ) was higher (P � 0.01) for the AA than A
group irrespective of gender.
The mean � SD physiological responses at peak cycle
ergometer exercise are listed in Table 2. A summary of the
ANOVA for these data is also listed in this table. A significant
(P � 0.01) fitness main effect was found for V˙ O 2peak,
whereas the gender main effect and the gender � fitness
interaction effect were not significant. The gender and fitness
main effects and the gender � fitness interaction effect
were not significant for HR and RER at peak intensities.
These analyses indicated that V˙ O 2peak (L·min �1 ) was higher
for the AA than A group independent of gender. Peak values
TABLE 2. Peak physiological responses during graded cycle ergometer exercise in
8- to 12-yr-old female and male subjects.
Fitness M � SD M � SD M � SD
A-Female 1.72 � 0.20 194.0 � 4.9 1.09 � 0.04
A-Male 1.79 � 0.21 194.7 � 4.3 1.10 � 0.03
AA-Female 2.04 � 0.24 196.0 � 6.1 1.10 � 0.04
AA-Male 2.10 � 0.17 196.4 � 6.1 1.10 � 0.04
Source
for HR and RER did not differ between the four gender �
fitness groups.
Figure 2A presents the mean � SD RPE responses at
peak exercise. The ANOVA for these data are summarized
in Table 3. Statistical significance was not found for either
the RPE, gender, and fitness main effects or any of the
interaction effects. The Mauchly W (0.95) test of sphericity
was not significant (P � 0.35). These analyses indicated that
the undifferentiated and differentiated RPE at peak exercise
intensity did not differ between the four gender � fitness
experimental groupings.
The physiological responses at the Vpt are listed in Table
4. Statistical analysis indicated that the fitness main effect
was significant (P � 0.01), whereas the gender main effect
and the gender � fitness interaction effect were not significant
for %V˙ O 2peak, V˙ O 2, and HR at the Vpt. The analyses
indicated that each of the physiological responses at Vpt was
significantly higher for the AA than A group independent of
gender. Figure 2B presents the undifferentiated and differentiated
perceived exertion responses at the Vpt. The
ANOVA for these data are summarized in Table 5. The
main effect for RPE was significant (P � 0.01), whereas the
main effects for fitness and gender were not significant.
Significant interaction effects were not found. The Mauchly
W (0.99) test of sphericity was not significant (P � 0.86).
These analyses indicated that when measured at the Vpt,
RPE-Overall, RPE-Legs, and RPE-Chest did not differ between
any of the four gender � fitness groups. Post hoc
analysis of the RPE main effect indicated that within all four
gender � fitness groups, RPE-Legs was greater than
RPE-Chest.
DISCUSSION
V˙O 2
(L�min –1 )
F
HR
(beats�min –1 ) RER
V˙O 2 HR RER
P
Value F
P
Value F
P
Value
Gender 0.04 0.84 0.12 0.73 0.35 0.56
Fitness 36.20 0.01* 1.40 0.24 1.02 0.32
Gender � fitness 0.00 0.99 0.01 0.94 0.03 0.86
V˙ O2, oxygen uptake; HR, heart rate; RER, respiratory exchange ratio; A, average fitness;
AA, above average fitness.
Data are means (M) � standard deviation (SD); df: gender � 1, fitness � 1,
gender � fitness � 1, error � 44.
* Significant.
Descriptive data. The mean � SD V˙ O 2peak for the four
gender � fitness experimental groups fell within the ranges
reported previously for North American female and male
children 8 to 12 yr of age (28). The mean Vpt was 64.0%
V˙ O 2peak for the A cohort and 74.0% V˙ O 2peak for the AA
cohort. These data are generally consistent with previous
RPE AT VENTILATORY BREAKPOINT Medicine & Science in Sports & Exercise � 1949

FIGURE 2—Mean � SD ratings of perceived exertion (RPE: OMNI
Scale) at peak exercise (A) and ventilatory breakpoint (B) in female
and male children (8–12 yr) with average (41.0–49.0 mL·kg �1 ·min �1 )
and above average (50.0–58.0 mL·kg �1 ·min �1 ) peak oxygen uptake
(V˙ O 2peak).
experiments that have determined Vpt during cycle ergometry
using clinically normal children who varied in peak
aerobic power (7,15,27,28).
Of importance from a perceptual scaling perspective are
the RPE responses obtained at peak cycle exercise intensity
in the four gender � fitness groups. The upper terminal RPE
derived from the OMNI Scale was very close to 10 for both
the undifferentiated and differentiated responses when examined
across individual subjects. When using category
rating scales to estimate exertional perceptions, it is important
that the upper terminal category (i.e., 10, OMNI Scale)
on the perceptual response range generally corresponds to
attainment of peak intensity on the exercise stimulus range.
Such correspondence is consonant with the basic tenants of
Borg’s Range Model (16,p.60) and is methodologically requisite
to interindividual comparisons of category rating scale
responses. The Range Model predicts that the highest terminal
response category should be similar between undifferentiated
and differentiated perceptual signals at peak exercise
intensity when signal-specific anchoring procedures
are used. The perceptual responses at peak cycle ergometer
exercise obtained presently provide evidence that the pic-
torially interfaced cognitive scale anchoring procedures (22)
used in conjunction with the Children’s OMNI Scale were
understood and appropriately applied by the subjects.
RPE-Overall at Vpt. In the present investigation, it was
hypothesized that the RPE-Overall corresponding to the Vpt
during cycle ergometry would be similar between pediatric
groups that differed in both their peak aerobic power (i.e.,
“average” vs “above average”) and in the %V˙ O 2peak that
was equivalent to their individually determined Vpt. The
findings supported this experimental hypothesis. The RPE-
Overall-Vpt was � 6 for both the A and AA groups. This
numerical category corresponds to the verbal descriptor
“tired” on the OMNI Scale. The finding is indicative of a
response normalized RPE-Overall-Vpt (OMNI Scale) for 8to
12-yr-old female and male children having a V˙ O 2peak
between 41 and 58 mL·kg �1 ·min �1 .
The variability in RPE-Overall-Vpt derived from the
OMNI Scale was comparatively small as evidenced by an
SD of � 0.62 for the low and � 0.66 for the high cohort.
Individual RPE-Overall-Vpt ranged from 5 to 7 within both
fitness groups. The OMNI Scale contains developmentally
and cognitively discrete measurement properties specific to
children 12 yr of age and younger (22). The comparatively
small variability in response normalized RPE-Overall-Vpt
derived from the OMNI Scale in the present investigation
reflects these measurement properties. A narrow perceptual
response range corresponding to a “target” physiological
reference is necessary for various response normalized applications
of RPE involving prescription and regulation of
exercise intensity.
Differentiated RPE. Ratings of perceived exertion that
are anatomically differentiated to specific body regions such
as the legs and chest are often used, respectively, in limbspecific
exercise prescriptions (1) and in clinical assessment
of exertional dyspnea (16,pp.245–247). Both of these procedures
involving differentiated RPE can be facilitated by
response normalized perceptual modeling.
It was hypothesized that both the RPE-Legs-Vpt and
RPE-Chest-Vpt during cycle ergometry would be similar
between pediatric groups differing in peak aerobic power.
The findings were consistent with this experimental hypothesis.
Both RPE-Legs and RPE-Chest exhibited stable responsiveness
between the four gender � fitness groups
when measured at the Vpt. The present responses provide
evidence that the OMNI Scale can be used to identify
response normalized RPE-Vpt that are anatomically differentiated
to the legs and chest in 8- to 12-yr-old children.
A differentiated exertional rating arising from the legs
reflects peripheral perceptual signals, whereas a rating differentiated
to the chest reflects respiratory-metabolic perceptual
signals (16,pp.105–106). A number of previous experiments
involving adult (17,21) and pediatric (2,15)
groups observed that RPE-Legs was higher than RPE-Chest
(2,17,21) when examined over a comparatively wide range
of cycle ergometer exercise intensities. Although it was not
possible to ascertain statistical significance, Mahon et al.
(15) using the Borg Scale reported that RPE-Legs was
greater than RPE-Chest in young children exercising at an
1950 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org

TABLE 3. Summary of ANOVA for RPE at peak exercise intensity and the ventilatory breakpoint.
intensity equivalent to the Vpt. Similarly, in the present
investigation, RPE-Legs at the Vpt was found to be the
dominant perceptual signal for the four gender � fitness
groups that were studied. These findings indicate that the
Children’s OMNI Scale is an effective psychometric tool to
assess the comparative strength of differentiated perceptual
signals at exercise intensities equivalent to the Vpt during
cycle ergometry.
Gender effect: RPE-Vpt. The undifferentiated and
differentiated RPE-Vpt did not differ between females
and males within and between fitness groupings. Previous
investigations (19,20,28) report that the Vpt is generally
independent of gender in young children (i.e., �12 yr of
age), provided that V˙ O 2max/peak does not differ between
gender groupings. As such, it was expected that the
RPE-Vpt would not differ between female and male children
within a given fitness group. The perceptual responses
confirmed this hypothesis. The findings of a
stable undifferentiated and differentiated RPE-Vpt determined
by the OMNI Scale applies to both female and
male children (8–12 yr old) who are classified as average
to above average in aerobic fitness.
Response normalized RPE applications. The identification
of a response normalized RPE corresponding to
the physiological and/or physical parameters that define the
TABLE 4. Physiological responses at the ventilatory breakpoint during cycle
ergometer exercise in 8- to 12-yr-old female and male subjects.
%V˙O 2peak
V˙O 2
(L�min –1 )
HR
(beats�min –1 )
Fitness M � SD M � SD M � SD
A-Female 64.0 � 3.3 1.10 � 0.18 148.8 � 5.5
A-Male 63.5 � 3.1 1.20 � 0.18 149.3 � 5.5
AA-Female 74.0 � 3.8 1.51 � 0.16 163.1 � 5.6
AA-Male 73.5 � 3.7 1.50 � 0.17 165.1 � 5.8
Source
Source
F
%V˙O 2peak V˙O 2 HR
P
Value F
df F
P
Value F
P
Value
Gender 0.24 0.63 0.00 0.99 0.02 0.88
Fitness 94.60 0.01* 69.30 0.01* 77.01 0.01*
Gender � fitness 0.00 1.0 0.00 0.99 0.02 0.88
%V˙ O2peak, percent of peak oxygen uptake; V˙ O2, oxygen uptake; HR, heart rate; A,
average fitness; AA, above average fitness.
Data are means (M) � standard deviation (SD); df: gender � 1, fitness � 1,
gender � fitness � 1, error � 44.
* Significant.
Peak Exercise Ventilatory Breakpoint
P
Value Eta 2 df F
Vpt has application in both exercise testing and prescription
(23). The present findings indicate that the exercise intensity
equivalent to the Vpt during a graded cycle ergometer test
can be identified using a response normalized RPE assessed
by the Children’s OMNI Scale. A response normalized
testing procedure eliminates the technically complex assessment
of pulmonary ventilation and respiratory gas exchange
typically used to determine the Vpt (18). This procedure is
particularly advantageous when assessing the Vpt in young
children who may have difficulty conforming to the time
and instrumentation demands of respiratory/metabolic measurements.
Once identified, the RPE-Vpt can be a prescriptive
reference to regulate multimodel exercise intensities
using a perceptual production paradigm (23). Duncan et al.
(7) have demonstrated that a response normalized perceptual
prescription is generalizable between cycle ergometer
and treadmill exercise in young children (10.2 yr old).
Additional research will need to be undertaken to determine
whether such cross-modal generalizability of the RPE-Vpt
occurs when assessments are made using the Children’s
OMNI Scale.
CONCLUSION
P
Value Eta 2
Between
Gender 1 0.60 0.44 0.01 1 0.02 0.89 0.00
Fitness 1 0.00 1.00 0.00 1 2.28 0.14 0.05
Gender � fitness 1 0.00 1.00 0.00 1 1.52 0.22 0.03
Error
Within
44 44
RPE 2 1.20 0.31 0.03 2 228.10 0.01* 0.84
RPE � gender 2 0.51 0.61 0.01 2 0.56 0.58 0.01
RPE � fitness 2 0.83 0.45 0.02 2 0.34 0.71 0.01
RPE � gender � fitness 2 0.12 0.89 0.00 2 0.49 0.62 0.01
Error
* Significant.
88 88
It is concluded that the Children’s OMNI Scale of Perceived
Exertion can be used to identify response normalized
undifferentiated (i.e., RPE-Overall, 6) and differentiated
(i.e., RPE-Legs, 7; RPE-Chest, 4.5) exertional perceptions
corresponding to the Vpt in young children. The children to
TABLE 5. Summary of ANOVA for RPE at the ventilatory breakpoint.
Source df F
P
Value Eta2 Between
Gender 1 0.02 0.89 0.00
Fitness 1 2.28 0.14 0.05
Gender � fitness 1 1.52 0.22 0.03
Error
Within
44
RPE 2 228.1 0.01* 0.84
RPE � gender 2 0.56 0.58 0.01
RPE � fitness 2 0.34 0.71 0.01
RPE � gender � fitness 2 0.49 0.62 0.01
Error
* Significant.
88
RPE AT VENTILATORY BREAKPOINT Medicine & Science in Sports & Exercise � 1951

whom these OMNI Scale RPE responses can be generalized
are 8- to 12-yr-old girls and boys having a V˙ O 2peak ranging
from 41.0 to 58.0 mL·kg �1 ·min �1 and a Vpt ranging from
64.0 to 74.0% V˙ O 2peak. Such age-specific responsiveness at
the Vpt provides a normalized perceptual reference for
prescription of exercise intensity in young children using the
OMNI Scale.
It is recognized that the foregoing conclusions were derived
from an experimental paradigm that exclusively used
the Children’s OMNI Scale to assess exertional perceptions.
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