Investigating the relationship between

subjective and objective exertion during a

cardiovascular fitness test in minority obese youth

Presented by: Marissa MenendezMajor Professor: Dr. Kathryn

Brogan

IntroductionAdolescent (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. (Physical Activity Guidelines, 2008)

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.

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)

Benefits of Moderate-Vigorous PAMVPA 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

5. Luszczynska et al., 2012, 6. Silva et al., 2012

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.

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)

Literature ReviewChildren 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)

SignificanceThere 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.

Aim 1

Aim 2

Aim 3

Methods

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 tempo

Chester step test: Instructions & Flow

181 ParticipantsAge (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

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

Frequency of Causes for Stopping CST Levels 1-5: Ages

12-16

66%10%

22%

2%

Age 12

RPEHRBothNeither 56%

18%

20%

6%

Age 13

47%

31%

19%

3%

Age 14

44%

13%

38%

5%

Age 15

62%14%

14%

10%

Age 16

Results: CST Stages 1-3

70%

17%

9% 4%

Stage 1: N=47, 26%

RPEHRBothNeither

47%

17%

29%

7%

Stage 2: N= 93, 52%

55%

12%

30%

3%

Stage 3: N=33, 18%

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

Unstandardized Coef.

Standardized Coef.

B St. Error Beta t Sig.

Constant

17.177 1.400 12.270 0.000

HR at completed 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

Aim 3 Results: Which variables affect the relationship between subjective &

objective exertion?Regression Model Summary

Variables

R R2Adjusted

R2

Std. Error of

the Estimat

e

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 .025Dependent Variable: RPE at completed step levelPredictor Variables: HR at completed step level X moderator variables

Body fat % moderates the relationship between subjective &

objective exertion

Low HR High HR16

16.2

16.4

16.6

16.8

17

17.2

17.4

17.6

17.8

18

Low % Body FatHigh % Body Fat

RPE

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.

Summary

DiscussionBorg’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 involved

Limitations

ConclusionAdolescents 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.

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 and PA recommendations. (Hoelscher et al. 2013)

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).

Thank You!Dr. BroganDr. TiuraFamilyA 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

References 1. Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of

obesity and trends in body mass index among US children and adolescents. JAMA. 2012;307:483-490.

2. Kann L, Kinchen S, Shanklin SL et al. Youth risk behavior surveillance — United States, 2013. MMWR. 2014;63(4):35-36.

3. Alfano, CM, Klesges, RC, Murray, DM, Beech, BM, & McClanahan, BS. History of sport participation in relation to obesity and related health behaviors in women. Preventive Medicine. 2002;34(1):82-89.

4. Reinehr T, Kleber M, Toschke AM. Lifestyle intervention in obese children is associated with a decrease of the metabolic syndrome prevalence. Atherosclerosis. 2009;207(1):174-180.

5. Reinehr T, Schaefer A, Winkel K, Finne E, Toschke AM, Kolip P. An effective lifestyle intervention in overweight children: Findings from a randomized controlled trial on “Obeldicks light”. Clinical Nutrition. 2010;29(3):331-336.

6. Gerber M, Brand S, Herrmann C, Colledge F, Holsboer-Trachsler E, Pühse U. Increased objectively assessed vigorous-intensity exercise is associated with reduced stress, increased mental health and good objective and subjective sleep in young adults. Physiol Behav. 2014;135(0):17-24.

References 7. Luszczynska A, Abraham C. Reciprocal relationships

between three aspects of physical self-concept, vigorous physical activity, and lung function: A longitudinal study among late adolescents. Psychol Sport Exerc. 2012;13(5):640-648.

8. Silva DAS, Petroski EL, Pelegrini A, Guglielmo LGA. Effect of physical exercise on the cardiorespiratory response in overweight adolescents. Turkish Journal of Endocrinology and Metabolism. 2012;16:14-18.

9. Healthy People 2020 Topics and Objectives: Physical Activity. U.S. Department of Health and Human Services. http://www.healthypeople.gov/2020/topicsobjectives2020/overview.aspx?topicid=33. Updated June 9, 2014. Accessed June 9, 2014.

10. Physical Activity Guidelines Advisory Committee: Physical activity guidelines advisory committee report. U.S. Department of Health and Human Services. http://www.health.gov/PAGuidelines/Report/pdf/CommitteeReport.pdf. Published 2008. Accessed June 9, 2014.

11. Morris M, Lamb K, Cotterrell D, Buckley J. Predicting maximal oxygen uptake via a perceptually regulated exercise test (PRET). Journal of Exercise Science & Fitness. 2009;7(2):122-128.

References 12. Pianosi PT, Huebner M, Zhang Z, McGrath PJ. Dalhousie

dyspnea and perceived exertion scales: Psychophysical properties in children and adolescents. Respiratory Physiology & Neurobiology. 2014;199(0):34-40.

13. Buckley JP, Sim J, Eston RG, Hession R, Fox R. Reliability and validity of measures taken during the chester step test to predict aerobic power and to prescribe aerobic exercise. Br J Sports Med. 2004;38:197-205.

14. Sykes K, Roberts A. The chester step test—a simple yet effective tool for the prediction of aerobic capacity. Physiotherapy. 2004;90(4):183-188.

15. Conley MM, Gastin PB, Brown H, Shaw C. Heart rate biofeedback fails to enhance children's ability to identify time spent in moderate to vigorous physical activity. Journal of Science and Medicine in Sport. 2011;14(2):153-158.

16. Fakhouri THI, Hughes JP, Burt VL, et al. Physical activity in U.S. youth aged 12–15 years, 2012. NCHS data brief, no 141. Hyattsville, MD: National Center for Health Statistics. 2014. http://www.cdc.gov/nchs/data/databriefs/db141.htm. Accessed September 6, 2014.

References17.

Cook S, Auinger P, Huang TTK. Growth Curves for Cardio-Metabolic Risk Factors in Children. J Pediatr. 2009;155(3): S6.e15–S6.e26.

18. Huebner M, Zhang Z, Therneau T, McGrath P, Pianosi P. Modeling trajectories of perceived leg exertion during maximal cycle ergometer exercise in children and adolescents. BMC Medical Research Methodology. 2014;14(4):1-9.

19. Fitzgerald N., Slawson D. Practice paper of the Academy of Nutrition and Dietetics: The Role of Nutrition is Health Promotion and Chronic Disease Prevention. J Acad Nutr Diet. 2013:1-13.

20. Barkley JE, Roemmich JN. Validity of a pediatric RPE scale when different exercise intensities are completed on separate days. Journal of Exercise Science & Fitness. 2011;9(1): 52-57

21. Elliott D, Abt G, Barry T. The effect of an active arm action on heart rate and predicted VO2max during the Chester step test. Journal of Science and Medicine in Sport. 2008;11(2):112-115.

22. Alves de Camargo A, Justino T, Silva de Andrade CH, Malaguti C, Dal Corso S. Chester step test in patients with COPD: Reliability and correlation with pulmonary function test results. Respiratory Care. 2011;56(7):995-1001.

23. Hoelscher DM, Kirk S, Ritchie L, Cunningham-Sabo L. J Acad Nutr Diet. Position of the Academy of Nutrition and Dietetics: Interventions for the Prevention and Treatment of Pediatric Overweight and Obesity. 2013;113(10):1375-1394.

Comparing HRMax, Intensity, RPE

Descriptive Statistics: CSTN 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 = PoorBorg’s RPE Scale: 6 = Very, Very Light; 20 = ExhaustionChester step test validity: 1 = Valid, no reason for concern; 2 = Uncertain, some reason for concern

80% Age-predicted HRMax

Results: CST Stages 1-5

70%

17%

9% 4%

Stage 1: N=47, 26%

RPEHRBothNeither

47%

17%

29%

7%

Stage 2: N= 93, 52%

55%

12%

30%

3%

Stage 3: N=33, 18%

50%25%

25%

Stage 4: N=4, 2%

100%

Stage 5: N=1, 1%

Aim 2 Results: Relationship between subjective and objective exertion

ANOVAb

Sum of Squares

df Mean Square

F Sig.

Regression

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 levelb. Dependent Variable: RPE Rate of perceived exertion at

completed step level

Aim 3 Results: Which variables affect the relationship between subjective &

objective exertion?ANOVAa

Variables Sum of Square

s dfMean

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 levelb. Predictor variables (constant): HR at completed step level X moderator variables

CST participant form