1. Investigating the relationship
between subjective and
objective exertion during a
cardiovascular fitness test in
minority obese youth
Presented by: Marissa Menendez
Major Professor: Dr. Kathryn Brogan

2. Introduction
 Adolescent (12-19 yrs.) obesity rates have  5% -
18% in last 30 years. (Ogden et. al., 2012)
 Obesity rates as high as 21% in non-Hispanic
black adolescents. (Ogden et al., 2012)
 Physical activity (PA): engaging in bodily
movements that increase heart rate & breathing
difficulty (aerobic).
 PA Guidelines for adolescents (12-17 yrs.) :
Aerobic – moderate (M) (50-70% HR Max) to
vigorous (V) (70-85% HR Max) intensity ≥ 60
minutes daily, including VPA at least 3 days/week.

3. What % of adolescents (12-15 yrs.) engaged
in moderate-to-vigorous PA for ≥ 60
minutes/day?
SOURCE (16): CDC/NCHS, National Health and Nutrition Examination Survey and National Youth
Fitness Survey, 2012.

4. Introduction
 PA levels of ≥60 minutes are lowest in
adolescent females compared to
males and in African Americans
compared to Caucasians. (Kann et al., 2014)
 Physical inactivity during adolescence
is a strong predictor of sedentary
adulthood. (Alfano et al., 2002)

5. Benefits of Moderate-Vigorous
PA
 MVPA in youth can : BMI,1,2 body fat
%,1 waist circumference,2,3 stress/pain
perceptions. 4
AND Improve: several obesity-related
conditions2 depressive symptoms,4
sleep patterns,4 physical
competence,5 body satisfaction,5
cardiovascular fitness & exercise
tolerance.6
1. Reinher et al., 2010, 2. Reinehr et al., 2009, 3. Sykes et al., 2004, 4.
Gerber et al., 2014

6. Does engagement in moderate-to-vigorous PA
among 12-15 yr. old youth differ by weight
status?
SOURCE (16): CDC/NCHS, National Health and Nutrition Examination Survey and National Youth Fitness
Survey, 2012.

7. Subjective vs. Objective
Exertion
 Rate of perceived exertion (RPE):
subjective measure of exercise
intensity that can safely regulate
exercise intensities in non-clinical
settings (Borg’s 6-20 RPE scale).
(Buckley et al., 2004)
 Objective exertion: actual heart rate
(HR) values can be use to regulate
exercise intensities via HR monitor.
(Buckley et al., 2004; Conley et al., 2011; McManus et al., 2008)

8. Literature Review
 Children and adolescents vary widely in their
abilities to rate their perceived exertions during
physical activity, even with HR biofeedback.
(Conley et al., 2011; McManus et al., 2008)
 Youth commonly over-or-underestimate their
actual (objective) exertion during MVPA. (Pianosi
et al., 2014)
 Children and adolescents lack the prior
experiences and PA perceptions to accurately
gauge the varying amounts of perceived
exertion at different intensities of exercise.
(Huebner et al, 2014)

9. Significance
 There is limited research on subjective
(RPE) and objective (HR) exertion levels
in African American obese youth.
 Adolescents who are able to successfully
associate their subjective and objective
exertion may be better able to properly
regulate their exercise intensities during
PA & effectively achieve PA
recommendations.

10. Aim 1
Aim
• To describe the subjective exertion (Borg’s
Scale of RPE) and objective exertion (heart
rate) in African American adolescents with
obesity (AAAO) performing a fitness test.
Analysis
• SPSS 21.0; p < 0.05 statistically significant
• Descriptive statistics (min./max., range,
mean, standard deviation) were used to
describe objective (heart rate) and
subjective exertion (Borg’s 6-20 scale of
RPE) at each fitness level

11. Aim 2
Aim
• To investigate the relationship between subjective
exertion (Borg’s Scale of RPE) and objective
exertion (heart rate) in AAAO performing a fitness
test.
Hypoth
• A weak relationship exists between subjective
exertion and objective exertion in obese African
American adolescents performing a fitness test.
Analysis
• Linear regression, ANOVA & standardized
coefficient beta were used to analyze the
relationship between HR and RPE.

12. Aim 3
Aim
• To examine the effects of the age, gender, BMI, body fat
percentage, waist circumference and presence of co-
morbidities, on subjective exertion (Borg’s Scale of
RPE) and objective exertion (heart rate) in AAAO
performing a fitness test.
Hypoth
• Older youth, males and youth with lower BMI, body fat
%, waist circumference and fewer co-morbidities will
have a stronger relationship between subjective and
objective exertion during a fitness test
Analysis
• Multiple linear regression, ANOVA and simple slopes
test were used to examine how the moderator variables
affect the relationship between subjective and objective
exertion.

13. Methods
Parent Study: FIT
Families Project: 6 month
behavioral weight loss
study
181 Obese African
American
adolescents 12-16
years old
Baseline data,
anthropometrics,
CST
All parent study
data de-
identified, using
patient IDs; IRB
Secondary
analysis of
cardiovascular
fitness test

14. Chester Step Test
(CST) Methods
 5 stages, 2 minutes each, tempo
begins at 15 steps/min. increasing 5
steps/min. each successful stage; 12
inch step
 HR Max & 80% HR Max calculated
 HR monitor e-pulse display and
sensor
 Demonstration/explanation of CST &
stepping technique to metronome

16. Chester step test: Instructions &
Flow
Adolescent
steps to pre-
recorded
metronome
beat on CD for
2 min.
HR & RPE
recorded
during last 3
seconds of
each stage
Adolescent
reaches ≥ 80%
HR Max and/or
reports RPE
≥14
CST STOPS:
Final step level
completed,
HR/RPE
recorded
CST continues to each
successive stage if HR
Max <80% & RPE <14

17. 181 Participants
 Age (yrs.): M=13.8 ± 1.4 SD (12-16)
 Weight (avg. lbs.) = 230 ± 51.1 SD (133-451)
 BMI (kg/m2): M=38.2 ± 7.5 SD (25.7-60.5)
 Waist Circ. (in.): M=43.9 ± 6.5 SD (32-66)
 Body Fat %: M=48 ± 7.3 SD (29.7-65.6)
 67% Female
 50% Co-morbidities: diagnosis of diabetes, asthma,
hypertension, sleep apnea

18. Aim 1 Results: Describing the subjective &
objective exertion of African American obese
adolescents
55%
17%
23%
5%
Frequency of Causes for Stopping CST at all
ages 12-16: Levels 1-5
RPE
HR
Both
Neither

19. Frequency of Causes for Stopping
CST Levels 1-5: Ages 12-16
66%
10%
22%
2% Age 12
RPE
HR
Both
Neither
56%
18%
20%
6%
Age 13
47%
31%
19%
3%
Age 14
44%
13%
38%
5%
Age 15
62%14%
14%
10%
Age 16

20. Results: CST Stages 1-3
70%
17%
9%
4%
Stage 1: N=47, 26%
RPE
HR
Both
Neither
47%
17%
29%
7%
Stage 2: N= 93, 52%
55%
12%
30%
3%
Stage 3: N=33, 18%

21. Aim 2 Results: Relationship between
subjective and objective exertion
Regression Model Summary
R R2 Adjusted R St. Error of
Estimate
.134a .018 .012 2.038
Coefficientsb
Unstanda
rdized
Coef.
Standardi
zed Coef.
B St. Error Beta t Sig.
Constant 17.177 1.400 12.270 0.000
HR at
complete
d step
level
-0.016 0.009 -0.134 -1.790 0.075
a. Predictors: (Constant), HR Heart rate at completed step level
b. Dependent Variable: RPE Rate of perceived exertion at
completed step level

22. Aim 3 Results: Which variables affect the
relationship between subjective & objective
exertion?
Regression Model Summary
Variables
R R2
Adjusted
R2
Std. Error
of the
Estimate
St.
Coef.
Beta
t Sig.
Age .135 .018 .001 2.049 -.019 -.246 .806
Gender .144 .021 .004 2.047 -.057 -.549 .584
BMI .178 .032 .015 2.035 .107 1.359 .176
Waist
Circ.
.181 .033 .016 2.034 .087 1.124 .263
Co-
morb.
.150 .023 .006 2.045 .030 .284 .777
Body fat
%
.234 .055 .038 2.020 .170 2.255 .025
Dependent Variable: RPE at completed step level
Predictor Variables: HR at completed step level X moderator variables

23. Body fat % moderates the relationship
between subjective & objective exertion
16
16.2
16.4
16.6
16.8
17
17.2
17.4
17.6
17.8
18
Low HR High HR
RPE
Low % Body Fat
High % Body Fat
Among adolescents with higher % body fat, the higher the actual heart rate, the
higher the RPE score.
Among adolescents with lower % body fat, the higher the actual heart rate, the lower
the RPE score.

24. Summary
AIM1: Overall, 55% of
adolescents stopped the CST
because of their perceived
exertion ≥14, 17% for objective
exertion, 23% matched.
AIM 2: Subjective exertion and
objective exertion were
marginally related (beta = -
0.134)
AIM 3: Body fat % was the only
moderator variable to
significantly affect the strength in
relationship between subjective
and objective exertion

25. Discussion
 Borg’s 6-20 scale of RPE extensively
used in CST, although OMNI &
Dalhousie pictorial scales may be more
appropriate for youth. (Pianosi, 2014; Barkley,
2011; Elliott, 2008; Alves de Camargo, 2011)
 With/without HR biofeedback youth
over-and-under estimate time spent in
MVPA, but higher % overestimate. (Conley
et al., 2011)
 Limited evidence on how body fat %
moderates the relationship between HR
and RPE – fitness levels could be

26. Limitations
Results
generalized to
African
American
obese
adolescents
CST not
validated in
adolescent
population
Pre-
existing
knowledge
of exercise
experience
Medicatio
n effects

27. Conclusion
 Adolescents need to be well-trained to
identify their exercise intensities to
appropriately self-regulate their PA to
achieve recommended guidelines of ≥
60 minutes of MVPA daily, including VPA
≥ 3 days/wk. (Physical Activity Guidelines, 2008).
 Youth could greatly benefit from
dietitians assisting them in accurately
identifying MVPA and closely matching
subjective & objective exertion, to
successfully overcome this barrier.

28. Implications for Dietetic Practice:
AND
 Weight management interventions combining
PA, dietary intake/nutrition education,
behavior counseling & caregiver engagement
have achieved successful outcomes in
overweight and obese adolescents (Reinehr et al.,
2010; Covelli, 2008; Hoelscher et al., 2013)
 Nutrition professionals: role/responsibility to
utilize nutrition & PA recommendations to
promote and maintain optimum health
throughout the lifecycle. (Fitzgerald and Slawson, 2013)
 RDs need adequate training/skills for
challenges of child-obesity epidemic:
assessment of body size, diet & PA;
knowledge of weight management strategies

29. Future Research
 Culturally targeted long-term interventions
needed for different types and intensities of
exercise in African American obese
adolescents. (Zoorob et al., 2013)
 Research investigating the effects of age,
gender, BMI, waist circumference, co-
morbidities & body fat % on RPE & HR
during different physical activities.
 Investigating the PA knowledge/skills of
nutrition professionals and implementation
strategies of the youth physical activity
recommendations (utilization of the AND PA
toolkit for RDs).

30. Thank You!
Dr. Brogan
Dr. Tiura
Family
A Teacher Affects Eternity. She can
never tell where her influence
stops.
Author Unknown
Exercise is King, Nutrition is Queen.
Put them together and you have a
Kingdom! Jack Lalane

31. References
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and trends in body mass index among US children and adolescents.
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32. References
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33. References
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effective tool for the prediction of aerobic capacity.
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Accessed September 6, 2014.

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35. Comparing HRMax, Intensity,
RPE

36. Descriptive Statistics: CST
N Minimum Maximum Mean
Std.
Deviation
Aerobic
Capacity
(mlsO2/kg/
min)
178 17 67 31.70 9.975
Fitness
Rating 178 1 5 4.01 1.107
Step level
completed 178 1 5 1.98 .770
HR at
completed
step level
(bpm)
178 78 197 157.99 17.393
RPE at
completed
step level
178 8 20 14.69 2.051
Chester
step test
validity
166 1 2 1.01 .078
Fitness Rating: 1 = Excellent, 2 = Above Average, 3 = Average, 4 = Below
Average, 5 = Poor
Borg’s RPE Scale: 6 = Very, Very Light; 20 = Exhaustion
Chester step test validity: 1 = Valid, no reason for concern; 2 = Uncertain, some
reason for concern

37. 80% Age-predicted HRMax
Age 12
Max HR = 208bpm
80% Max HR: 166bpm
Age 13
Max HR 207bpm
80% Max HR: 166bpm
Age 15
Max HR = 205bpm
80% Max HR:
164bpm
Age 14
Max HR = 206bpm
80% Max HR:
165bpm
Age 16
Max HR = 204bpm
80% Max HR:
163bpm

38. Results: CST Stages 1-5
70%
17%
9%
4%
Stage 1: N=47, 26%
RPE
HR
Both
Neither
47%
17%
29%
7%
Stage 2: N= 93, 52%
55%
12%
30%
3%
Stage 3: N=33, 18%
50%
25%
25%
0%
Stage 4: N=4, 2%
0%
100%
0%0%
Stage 5: N=1, 1%

39. Aim 2 Results: Relationship between
subjective and objective exertion
ANOVAb
Sum of
Squares
df Mean
Square
F Sig.
Regressi
on
13.313 1 13.313 3.205 0.075a
Residual 731.069 176 4.154
Total 744.382 177
a. Predictors: (Constant), HR Heart rate at completed step level
b. Dependent Variable: RPE Rate of perceived exertion at completed step
level

40. Aim 3 Results: Which variables affect the
relationship between subjective & objective
exertion?
ANOVAa
Variables Sum of
Squares df
Mean
Square F Sig.
Age Regression 13.579 3 4.526 1.078 .360b
Residual 730.804 174 4.200
Gender Regression 15.341 3 5.114 1.220 .304b
Residual 729.041 174 4.190
BMI Regression 23.649 3 7.883 1.903 .131b
Residual 720.733 174 4.142
Wst Circ. Regression 24.413 3 8.138 1.967 .121b
Residual 719.969 174 4.138
Co-morb. Regression 16.817 3 5.606 1.341 .263b
Residual 727.565 174 4.181
BF % Regression 40.820 3 13.607 3.335 .021b
Residual 701.719 172 4.080
a. Dependent variable: RPE at completed step level
b. Predictor variables (constant): HR at completed step level X moderator variables

41. CST participant form