Sympathetic Activity Assessed during Exercise Recovery in Young Obese Females

• Published in: The Journal of pediatrics 2015-08, Vol.167 (2), p.378-383.e1
• Main Authors: Franco, R. Lee, PhD, Privett, Stacey H., MS, Bowen, Mary K., MS, Acevedo, Edmund O., PhD, Arrowood, James A., MD, Wickham, Edmond P., MD, Evans, Ronald K., PhD
• Format: Article
• Language: English
• Subjects: Adolescent; African Americans; Age Factors; Child; European Continental Ancestry Group; Exercise - physiology; Exercise Tolerance - physiology; Female; Heart Rate - physiology; Humans; Obesity - ethnology; Obesity - physiopathology; Oxygen Consumption - physiology; Pediatrics; Risk Factors; Sex Factors; Sympathetic Nervous System - physiopathology
• ISSN: 0022-3476; 1097-6833
• DOI: 10.1016/j.jpeds.2015.04.058

Objective To evaluate differences in sympathetic activity, as assessed by an exercise recovery index (ERI; heart rate/oxygen consumption [VO2 ] plateau), between black and white obese female adolescents. An additional aim was to determine the association of ERI with insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]), cardiovascular fitness per fat-free mass (VO2 per fat-free mass), systolic blood pressure (SBP), and percent body fat (%FAT) in both black and white obese adolescents. Study design Sixty-one females volunteered to participate in this study. HOMA-IR, SBP, and %FAT were assessed during resting conditions in black (n = 49, 13.7 ± 1.6 years, 38.1 ± 6.1 kg/m2 ) and white (n = 12, 13.3 ± 2.2 years, 34.3 ± 4.9 kg/m2 ) obese adolescents. An ERI was calculated during a 5-minute passive recovery period immediately following a graded treadmill exercise test to exhaustion. Results The ERI was significantly greater in black compared with white obese adolescent females (29.8 ± 6.4 vs 24.1 ± 3.1 bpm·mLO2−1 ·min−1 , P  = .004). Using multiple linear regression modeling, there was a significant independent association between ERI and VO2 per fat-free mass (r = −0.310, P  = .027) and %FAT (r = 0.326, P  = .020) in black obese adolescents after controlling for HOMA-IR and SBP. Conclusions These results suggest that black obese adolescent females have greater sympathetic activity, as assessed by an ERI, than white obese adolescent females. These findings support the need for weight management efforts aimed at both reducing %FAT and improving fitness in obese adolescents, specifically black females. Trial registration Registered with Clinicaltrials.gov : NCT00562293