The role of parents in behavioral treatment for adolescent obesity: design and rationale for the TEENS+ randomized clinical trial.

BACKGROUND: There is an urgent need for innovative approaches to adolescent obesity treatment, particularly among individuals from racially and ethnically marginalized backgrounds, who face increased risk of obesity and its associated morbidity and mortality. There is a particular dearth of research on the long-term efficacy of adolescent obesity treatments. Further, research and clinical practice guidelines consistently recommend parents' inclusion in their adolescents' obesity treatment, yet the most effective strategy to engage parents in adolescent obesity treatment remains unclear. Towards that end, this investigation will conduct a fully-powered, randomized clinical trial to examine the efficacy of two distinct approaches to involving parents in their adolescents' obesity treatment. METHODS: Participants will be 210 12-16 year old adolescents (body mass index [BMI]≥85th percentile) and parents (BMI≥25 kg/m2) with overweight or obesity. Dyads will be randomized to one of two 4-month treatments: 1) TEENS+Parents as Coaches (PAC), engaging parents as helpers in their child's weight management via parent skills training based on authoritative parenting, or 2) TEENS+Parent Weight Loss (PWL), engaging parents in their own behavioral weight management. All adolescents will participate in the TEENS+ protocol, which includes nutrition education with dietary goals, supervised physical activity, and behavioral support, and integrates motivational interviewing to enhance treatment engagement. Assessments of anthropometrics, dietary intake, physical activity, parenting and home environment variables will be completed at 0, 2, 4, 8, and 12 months with the primary endpoint at 12-month follow-up. DISCUSSION: Results of this investigation have the potential to significantly advance science in this area and ultimately inform clinical practice guidelines related to the role of parents in adolescent obesity treatment. TRIAL REGISTRATION: Clinicaltrials.gov NCT03851796. Registered: February 22, 2019.

Effect of a Lifestyle Intervention on Cardiometabolic Health Among Emerging Adults: A Randomized Clinical Trial.

Importance: The prevalence of obesity has increased substantially among emerging adults, yet no previous large-scale behavioral weight loss trials have been conducted among this age group. Objective: To test the effect of 2 theory-based motivational enhancements on weight loss within a primarily digital lifestyle intervention designed for emerging adults. Design, Setting, and Participants: In this randomized clinical trial conducted at an academic medical research center, 382 participants aged 18 to 25 years with a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of 25 to 45 were enrolled between February 2, 2016, and February 6, 2019. Data collection was completed February 8, 2020. Analysis was performed on an intention-to-treat basis. Interventions: Participants were randomized to 1 of 3 groups: developmentally adapted behavioral weight loss (aBWL), aBWL plus behavioral economics (aBWL + BE), or aBWL plus self-determination theory (aBWL + SDT). All groups received a 6-month intervention with 1 group session, 1 individual session, and a digital platform (digital tools for self-monitoring, weekly lessons, tailored feedback, text messages, and optional social media). The aBWL + BE group received modest financial incentives for self-monitoring and weight loss; the aBWL + SDT group received optional experiential classes. Coaching and message framing varied by group. Main Outcomes and Measures: The primary outcome was mean (SE) weight change (in kilograms) at 6 months. Secondary outcomes included proportion of participants achieving weight loss of 5% or more, percentage weight change, waist circumference, body composition, and blood pressure. Results: Among the 382 participants (mean [SD] age, 21.9 [2.2] years), 316 (82.7%) were female, mean (SD) BMI was 33.5 (4.9), 222 (58.1%) were of underrepresented race and/or ethnicity, and 320 (83.8%) were retained at the primary end point. There was a significant time effect for mean (SE) weight loss (-3.22 [0.55] kg in the aBWL group; -3.47 [0.55] kg in the aBWL + BE group; and -3.40 [0.53] kg in the aBWL + SDT group; all P < .001), but no between-group differences were observed (aBWL vs aBWL + BE: difference, -0.25 kg [95% CI, -1.79 to 1.29 kg]; P = .75; aBWL vs aBWL + SDT: difference, -0.18 kg [95% CI, -1.67 to 1.31 kg]; P = .81; and aBWL + SDT vs aBWL + BE: difference, 0.07 kg [95% CI, -1.45 to 1.59 kg]; P = .93). The proportion of participants achieving a weight loss of 5% or more was 40.0% in the aBWL group (50 of 125), 39.8% in the aBWL + BE group (51 of 128), and 44.2% in the aBWL + SDT group (57 of 129), which was not statistically different across groups (aBWL vs aBWL + BE, P = .89; aBWL vs aBWL + SDT, P = .45; aBWL + SDT vs aBWL + BE, P = .54). Parallel findings were observed for all secondary outcomes-clinically and statistically significant improvements with no differences between groups. Conclusions and Relevance: In this randomized clinical trial, all interventions produced clinically significant benefit, but neither of the motivational enhancements promoted greater reductions in adiposity compared with the developmentally adapted standard group. Continued efforts are needed to optimize lifestyle interventions for this high-risk population and determine which intervention works best for specific individuals based on sociodemographic and/or psychosocial characteristics. Trial Registration: ClinicalTrials.gov Identifier: NCT02736981.

Influence of extracellular volume fraction on peak exercise oxygen pulse following thoracic radiotherapy.

BACKGROUND: Radiation-induced myocardial fibrosis increases heart failure (HF) risk and is associated with a restrictive cardiomyopathy phenotype. The myocardial extracellular volume fraction (ECVF) using contrast-enhanced cardiac magnetic resonance (CMR) quantifies the extent of fibrosis which, in severe cases, results in a noncompliant left ventricle (LV) with an inability to augment exercise stroke volume (SV). The peak exercise oxygen pulse (O2Pulse), a noninvasive surrogate for exercise SV, may provide mechanistic insight into cardiac reserve. The relationship between LV ECVF and O2Pulse following thoracic radiotherapy has not been explored. METHODS: Patients who underwent thoracic radiotherapy for chest malignancies with significant incidental heart dose (≥5 Gray (Gy), ≥10% heart) without a pre-cancer treatment history of HF underwent cardiopulmonary exercise testing to determine O2Pulse, contrast-enhanced CMR, and N-terminal pro-brain natriuretic peptide (NTproBNP) measurement. Multivariable-analyses were performed to identify factors associated with O2Pulse normalized for age/gender/anthropometrics. RESULTS: Thirty patients (median [IQR] age 63 [57-67] years, 18 [60%] female, 2.0 [0.6-3.8] years post-radiotherapy) were included. The peak VO2 was 1376 [1057-1552] mL·min- 1, peak HR = 150 [122-164] bpm, resulting in an O2Pulse of 9.2 [7.5-10.7] mL/beat or 82 (66-96) % of predicted. The ECVF, LV ejection fraction, heart volume receiving ≥10 Gy, and NTproBNP were independently associated with %O2Pulse (P < .001). CONCLUSIONS: In patients with prior radiotherapy heart exposure, %-predicted O2Pulse is inversely associated markers of diffuse fibrosis (ECVF), ventricular wall stress (NTproBNP), radiotherapy heart dose, and positively related to LV function. Increased LV ECVF may reflect a potential etiology of impaired LV SV reserve in patients receiving thoracic radiotherapy for chest malignancies.

The role of parents in adolescent obesity treatment: Results of the TEENS+ randomized clinical pilot trial.

BACKGROUND: The optimal role for involving parents in adolescent obesity treatment is unknown. OBJECTIVE: To demonstrate that two parent approaches within adolescent obesity treatment are distinct, as evidenced by differential parent outcomes, and determine the preliminary efficacy of each approach on adolescent weight loss. METHODS: Adolescent/parent dyads (N = 82; mean adolescent age = 13.7 ± 1.2 years) participated in TEENS+, a 4-month behavioural weight loss treatment. Participants were randomized to: (1) TEENS+parents as coaches (PAC; parent skills training), or (2) TEENS+parent weight loss (PWL; adult behavioural weight loss). Assessments occurred at 0, 4 (post-treatment), and 7-months. Within- and between-group repeated measures general linear mixed models examined change in parent weight (∆kg; primary outcome); parenting, feeding, weight control strategies, home environment, and adolescent body mass index (∆BMI; secondary outcomes). RESULTS: PWL parents had greater 4-month weight losses (∆kg0-4m  = -5.14 ± 4.87 kg) compared to PAC (-2.07 ± 3.89 kg; between-group p < 0.01). Key constructs differed between groups as expected. Both groups yielded significant within-group adolescent ∆BMI0-4m (PWL: -0.97 ± 1.38 kg/m2 vs. PAC: -0.93 ± 1.42 kg/m2 ; ps < 0.01); during maintenance, adolescents in PWL had ∆BMI4-7m increases (+0.41 ± 1.07 kg/m2 ; p = 0.02) while PAC did not (+0.05 ± 1.31 kg/m2 ; p = 0.82). CONCLUSION: Parent treatments were distinct in implementation and both yielded significant 4-month adolescent weight loss. Differential weight patterns were observed during maintenance, favouring PAC, warranting further exploration.

Diastolic Dysfunction Contributes to Impaired Cardiorespiratory Fitness in Patients with Lung Cancer and Reduced Lung Function Following Chest Radiation.

Cardiorespiratory fitness (CRF) is a robust and independent predictor of cardiovascular health and overall mortality. Patients with lung cancer often have chronic lung disease, contributing to impaired CRF. Radiation to the heart during lung cancer treatment may further reduce CRF. The determinants of CRF in this population are not well understood. We prospectively evaluated 12 patients with lung cancer without known cardiovascular disease with reduced lung function receiving curative intent thoracic radiotherapy to determine whether cardiac diastolic function, as assessed by Doppler echocardiography and N-terminal pro-brain natriuretic peptide (NTproBNP) levels, correlate with CRF measured by peak oxygen consumption (VO2). Doppler-derived measures of diastolic function and serum NTproBNP levels inversely correlated with peak VO2. In a multivariate regression model, NTproBNP was the strongest independent variable associated with peak VO2. These results suggest that diastolic dysfunction further contributes to reduced CRF in patients with lung cancer who have received radiotherapy.

Using measured resting metabolic rate to derive calorie prescriptions in a behavioral weight loss program.

OBJECTIVE: Within behavioral weight loss (BWL) programs, using measured resting metabolic rate (RMR) is a more accurate-yet costlier-alternative to the standard method of assigning calorie prescriptions using baseline weight. This investigation aimed to assess differences between calorie goals prescribed using each method including demographic predictors and associations with weight loss. METHODS: This is an ancillary study to a trial comparing approaches to motivational enhancement in a 6-months BWL program designed for emerging adults age 18-25 (N = 308). RMR was measured at baseline and used to derive calorie prescriptions; standard calorie goals were retrospectively assigned for the purpose of these analyses. RESULTS: Standard calorie prescriptions were significantly higher than those derived from RMR. Sex and race were significant predictors of calorie prescription discrepancies: using the standard method, women and Black participants were assigned higher calorie goals than their RMR would indicate. Calorie goal discrepancy did not predict 6-months weight change. CONCLUSIONS: Differences in calorie prescriptions between approaches were significant; however, it remains to be determined whether measuring RMR is worth the cost, time, and participant burden. It may be the case that this consideration has greater impact for certain subgroups-namely, women and Black participants.

Behavioral weight loss in emerging adults: Design and rationale for the Richmond Emerging Adults Choosing Health (REACH) randomized clinical trial.

BACKGROUND: In the U.S., over 40% of 18-25 year olds meet criteria for overweight or obesity. Yet, no large-scale trials have targeted this age group for behavioral weight loss (BWL). Formative data revealed that existing BWL programs do not meet their unique needs and identified motivation as a fundamental barrier for weight management. The goal of the Richmond Emerging Adults Choosing Health (REACH) trial was to test the efficacy of two mHealth lifestyle interventions specifically focused on enhancing motivation, relative to adapted standard. METHODS: Participants (N = 381, 18-25 years, body mass index 25-45 kg/m2) will be randomized to 1) adapted BWL (aBWL), 2) aBWL + self-determination theory (aBWL+SDT), or 3) aBWL + behavioral economics (aBWL+BE). All arms will receive a 6-month intervention, delivered via one group session and one individual session, followed by an mHealth platform. Assessments will occur at baseline, 3-months, 6-months (post-treatment) and 12-months (following a no-contact period). The primary aim is to compare weight loss outcomes at 6 months. Secondary aims include changes at 6-months in physical and behavioral cardiometabolic risk factors, as well as psychosocial measures. We will also explore weight loss maintenance, change in hypothesized mediators, and moderators of treatment response. DISCUSSION: REACH is the first large-scale BWL trial designed specifically for emerging adults. Further, it will be the first trial to compare a lifestyle intervention grounded in self-determination theory to one rooted in behavioral economics. If clinically significant reductions in adiposity are achieved, findings could inform a scalable treatment model to meet the needs of this vulnerable population. TRIAL REGISTRATION: NCT02736981.

An appraisal of whole-room indirect calorimeters and a metabolic cart for measuring resting and active metabolic rates.

Whole-room indirect calorimeters (WRICs) have traditionally been used for real-time resting metabolic rate (RMR) measurements, while metabolic rate (MR) during short-interval exercises has commonly been measured by metabolic carts (MCs). This study aims to investigate the feasibility of incorporating short-interval exercises into WRIC study protocols by comparing the performance of WRICs and an MC. We assessed the 40-min RMR of 15 subjects with 2-day repeats and the 10-15 min activity MR (AMR) of 14 subjects at three intensities, using a large WRIC, a small WRIC, and an MC. We evaluated the biases between the instruments and quantified sources of variation using variance component analysis. All three instruments showed good agreement for both RMR (maximum bias = 0.07 kcal/min) and AMR assessment (maximum bias = 0.53 kcal/min). Moreover, the majority of the variability was between-subject and between-intensity variation, whereas the types of instrument contributed only a small amount to total variation in RMR (2%) and AMR (0.2%) data. In Conclusion, the good reproducibility among the instruments indicates that they may be used interchangeably in well-designed studies. Overall, WRICs can serve as an accurate and versatile means of assessing MR, capable of integrating RMR and short-interval AMR assessments into a single protocol.

Increased C-reactive protein is associated with the severity of thoracic radiotherapy-induced cardiomyopathy.

BACKGROUND: Irradiation of the heart during cancer radiotherapy is associated with a dose-dependent risk of heart failure. Animal studies have demonstrated that irradiation leads to an inflammatory response within the heart as well as a reduction in cardiac reserve. In the current study we aimed to evaluate whether inflammatory biomarkers correlated with changes in cardiac function and reserve after radiotherapy for breast or lung cancer. METHODS AND RESULTS: We studied 25 subjects with a history of breast or lung cancer without a prior diagnosis of cardiovascular disease or heart failure, 1.8 years [0.4-3.6] post-radiotherapy involving at least 5 Gray (Gy) to at least 10% of the heart. High-sensitivity C-reactive protein (CRP) was abnormal (≥2 mg/L) in 16 (64%) subjects. Cardiac function and reserve was measured with Doppler echocardiography before and after exercise and defined as left-ventricular ejection fraction (LVEF), early diastolic mitral annulus velocity (e'), and increase in LV outflow tract velocity time integral cardiac output (cardiac reserve) with exercise. Subjects with abnormal CRP had significantly lower LVEF (51 [44-59] % vs 61 [52-64] %, P = 0.039), lower e' (7.4 [6.6-7.9] cm/sec vs 9.9 [8.3-12.0] cm/sec, P = 0.010), and smaller cardiac reserve (+ 1.5 [1.2-1.7] L/min vs + 1.9 [1.7-2.2] L/min, P = 0.024). CONCLUSION: Elevated systemic inflammation is associated with impaired left-ventricular systolic and diastolic function both at rest and during exercise in subjects who have received radiotherapy with significant incidental heart dose for the treatment of cancer.

Determinants of Cardiorespiratory Fitness Following Thoracic Radiotherapy in Lung or Breast Cancer Survivors.

We measured peak oxygen consumption (VO2) in previous recipients of thoracic radiotherapy and assessed the determinants of cardiorespiratory fitness with an emphasis on cardiac and pulmonary function. Cancer survivors who have received thoracic radiotherapy with incidental cardiac involvement often experience impaired cardiorespiratory fitness, as measured by reduced peak VO2, a marker of impaired cardiovascular reserve. We enrolled 25 subjects 1.8 (0.1 to 8.2) years following completion of thoracic radiotherapy with significant heart exposure (at least 10% of heart volume receiving at least 5 Gray). All subjects underwent cardiopulmonary exercise testing, Doppler echocardiography, and circulating biomarkers assessment. The cohort included 16 Caucasians (64%), 15 women (60%) with a median age of 63 (59 to 66) years. The peak VO2 was 16.8 (13.5 to 21.9) ml·kg-1·min-1 or moderately reduced at 62% (50% to 93%) of predicted. The mean cardiac radiation dose was 5.4 (3.7 to 14.7) Gray, and it significantly correlated inversely with peak VO2 (R = -0.445, p = 0.02). Multivariate regression analysis revealed the diastolic functional reserve index and the N-terminal pro-brain natriuretic peptide (NTproBNP) serum levels were independent predictors of peak VO2 (ß = +0.813, p <0.01 and ß = -0.414, p = 0.04, respectively). In conclusion, patients who had received thoracic radiation display a dose-dependent relation between the cardiac radiation dose received and the impairment in peak VO2, the reduction in diastolic functional reserve index, and elevation of NTproBNP.

Recruitment and retention of families interested in a parent-based pediatric obesity intervention.

Recruitment and retention in pediatric obesity treatment remains challenging, especially for groups at highest risk of this condition, including African Americans. However, most investigations examine attrition during intervention or follow-up. Little is known about those who refuse enrollment, or drop out at baseline. Thus, the trajectory of recruitment, enrollment, and retention, especially at these early stages, is not well understood, limiting knowledge of treatment access. This study examined enrollment in a pediatric weight management intervention. We provide demographic information on nested consort flow groups. We compared non-overlapping interest/enrollment groups to examine differences between those who progressed to the next consort flow group and those who did not; specifically the four groups examined were: (1) eligible at screening, did not attend baseline (n children  = 261), (2) attended baseline, did not enroll (n children  = 46), (3) enrolled, did not complete posttesting (n children  = 81), and (4) completed posttesting (n children  = 284). Of enrolled families, >70% were African American; >78% completed posttesting. No differences emerged across groups on sex, ethnicity, or race (ps > .05). Attrition was unrelated to initial child BMI. In this trial, the goal of enrolling diverse parents of children with obesity was achieved, and most enrollees completed treatment.

Exercise Capacity in Patients with the Total Artificial Heart.

There is a dearth of information regarding the functional abilities of patients with the total artificial heart (TAH). Increased utilization of the TAH and patient discharge to home with the portable unit necessitates a shift in focus to quality of life, which includes quantifying and ultimately optimizing functional capacity. To date, only single-patient case studies have described the exercise response of the TAH patient. Fourteen patients with the TAH underwent cardiopulmonary exercise testing with concurrent analysis of TAH device function. All device settings remained fixed during testing. Peak oxygen consumption (VO2; 0.872 L/min [interquartile range (IQR) = 0.828-1.100 L/min]), percent predicted peak VO2 (36% [IQR = 32-42%]), and ventilatory anaerobic threshold (0.695 L/min [IQR = 0.542-0.845 L/min]) were markedly reduced in the TAH compared with predicted normal values. Determinants of VO2 using device-generated hemodynamics revealed a blunted cardiac output (+9% increase) and exaggerated oxygen extraction with exercise. Peak VO2 strongly correlated with resting (R = +0.548, p = 0.045), ventilatory anaerobic threshold (R = +0.780, p = 0.001), and peak exercise cardiac output (R = +0.672, p = 0.008). Patients with the TAH have significantly impaired exercise performance. The limitations to cardiopulmonary exercise testing performance appear to be related to limited ability of the pump to modulate output for activity and reduced oxygen carrying capacity.

Excess Blood Flow Response to Acute Resistance Exercise in Individuals Who are Obese or Nonobese.

Lipford, GF, Evans, RK, Acevedo, EO, Wolfe, LG, and Franco, RL. Excess blood flow response to acute resistance exercise in individuals who are obese or nonobese. J Strength Cond Res 31(11): 3120-3127, 2017-Resistance exercise (RE) is a commonly recommended treatment option for obese individuals. However, little is known regarding alterations in vasodilatory responses to RE, which could impair exercise tolerance. No studies to date have compared microvascular vasodilatory capacity, assessed by excess blood flow (EBF), responses in individuals who are obese or nonobese following acute RE. The purpose of the study was to evaluate EBF before and up to 24-hour after a single RE bout in obese (n = 18, 38.1 ± 7.64% body fat) and nonobese (n = 10, 23.6 ± 4.03% body fat) individuals who volunteered to participate. Each subject completed a leg flexion and knee extension one repetition maximum (1RM) test, and subsequently completed 4 sets of 8 repetitions at 85% of 1RM. Excess blood flow, adiponectin, and tumor necrosis factor α (TNF-α) were evaluated at baseline (PRE-RE), immediately after (POST-RE), and 1 (POST-1) and 24 (POST-24) hours after exercise. A repeated-measures analysis of variance revealed a significant interaction for EBF between the 2 groups (p = 0.029). The estimated marginal means plot suggested that obese individuals had a significant increase in POST-RE EBF in comparison with PRE-RE EBF (428.54 ± 261.59 vs. 547.00 ± 311.15 ml/100 ml/min·s; p = 0.046). In addition, EBF significantly decreased at POST-24 in comparison with POST-RE in the obese individuals (547.00 ± 311.15 vs. 389.33 ± 252.32 ml/100 ml/min·s; p = 0.011). Changes in EBF were not related to adiponectin or TNF-α. An acute bout of RE resulted in an opposite EBF response between nonobese and obese individuals immediately after RE. Furthermore, only the obese individuals displayed a significant increase in EBF immediately after RE, which was significantly reduced 24 hours after the RE bout. Microvascular vasodilatory capacity may alter the adaptive exercise response associated with RE, requiring alterations to frequency, intensity, and/or duration that are specific to populations of various body composition profiles.

Assessment of Cardiopulmonary Responses to Treadmill Walking Following Gastric Bypass Surgery.

BACKGROUND: Studies that have evaluated cardiopulmonary responses to exercise within the first few months of bariatric surgery have utilized cycle ergometry. However, walking is the most commonly reported mode of both pre- and post-operative PA. The divergent cardiopulmonary responses and metabolic costs of weight-bearing (walking) and non-weight-bearing (cycling) exercises warrant examination of the effects of bariatric surgery on cardiopulmonary responses during walking. METHODS: Nine women completed a maximal cardiopulmonary exercise test on a treadmill 2 weeks before and 3 months after gastric bypass surgery (GBS). Heart rate (HR), oxygen uptake (VO2), oxygen pulse (O2-p), and time to fatigue were compared before and after surgery and between the GBS group and a comparison group of 12 normal-weight (NW) women who completed the same exercise testing protocol. RESULTS: Time to fatigue increased by ~140 s following GBS (p = 0.018). No other parameter improved during maximal exercise from pre- to post-surgery. Body weight- and fat-free mass-corrected VO2 and O2-p at peak exercise differed between the GBS and NW groups before surgery, while only weight-corrected values were different following surgery. These differences disappeared after controlling for body fat percentage. CONCLUSION: We have demonstrated that weight loss alone was not sufficient to improve select cardiopulmonary fitness measures during treadmill walking in obese females 3 months after GBS. However, we did observe a significant overall improvement in exercise capacity as the GBS group was able to exercise longer, presumably due to significant reductions in body mass and a subsequent reduced metabolic cost of walking.

Changes in Resting Energy Expenditure in Relation to Body Weight and Composition Following Gastric Restriction: A Systematic Review.

In comparison to gastric bypass surgery, gastric restriction without malabsorption more closely simulates dietary adherence while still producing durable weight loss. The latter is achieved despite considerable reductions in resting energy expenditure (REE), and whether REE is adjusted for body weight/composition using ratio- or regression-based methods could influence understanding of how these procedures affect energy balance. This systematic review identified studies that reported REE before and after gastric restriction in order to compare changes using each method. Ratio assessments revealed increases and decreases when REE was expressed per kilogram of body weight and per kilogram of fat-free mass, respectively. In comparison, measured REE tended to be less than predicted from linear regression after surgery. Explanations for these seemingly disparate findings and future directions are discussed.

Sympathetic Activity Assessed during Exercise Recovery in Young Obese Females.

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/m(2)) and white (n = 12, 13.3 ± 2.2 years, 34.3 ± 4.9 kg/m(2)) 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.

Cardiometabolic and Fitness Improvements in Obese Girls Who Either Gained or Lost Weight during Treatment.

OBJECTIVE: To evaluate the quality of weight change (change in fat mass vs fat-free mass [FFM]), changes in cardiorespiratory fitness (CRF), and frequencies of metabolic risk factors in adolescent females with obesity who either lost or gained weight following lifestyle treatment. STUDY DESIGN: Fifty-eight girls (mean age = 13.0 ± 1.6 years; 77% black; mean body mass index = 36.5 ± 4.5 kg/m(2)) completed a 6-month lifestyle intervention combining dietary and behavioral counseling with aerobic and resistance exercise training. We examined baseline to 6-month differences in weight (kg), body composition, CRF, and frequencies of metabolic risk factors between weight loss and weight gain groups. RESULTS: In the weight loss group, body weight (-4.50 ± 3.53 kg, P < .001), fat mass (-4.50 ± 2.20 kg, P < .001), and body fat percentage (-2.97% ± 1.45%, P < .001) decreased, and FFM was unchanged at 6 months. In the weight gain group, body weight (4.50 ± 2.20 kg, P < .001), fat mass (1.52 ± 3.16 kg, P < .024), and FFM (2.99 ± 2.45 kg, P < .001) increased, and body fat percentage was unchanged. Both groups improved CRF (P < .05). Frequencies of metabolic risk factors were reduced across all participants after the 6-month treatment. CONCLUSIONS: Participation in a weight management program might elicit health improvements in obese adolescent females who increase weight and fat mass, provided that FFM gains are sufficient to negate increases in body fat percentage. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00167830.

The contribution of fat-free mass to resting energy expenditure: implications for weight loss strategies in the treatment of adolescent obesity.

Owing to the strong relationship between fat-free mass (FFM) and resting energy expenditure (REE), the preservation of FFM is often emphasized in the treatment of adolescent obesity. Typical treatment regimens including an increased dietary consumption of protein and participation in resistance training are common components of adolescent weight management programs, despite limited evidence of a positive influence of FFM on weight loss outcomes in adolescents. Given the larger volume of FFM in obese relative to normal weight adolescents and the common treatment goals of both maximizing weight loss and attenuating the loss of FFM, a better understanding of the influence of FFM on energy balance is needed to determine whether strategies to preserve lean tissue or maximize absolute weight loss should be most emphasized. We review the associations among FFM, REE, and weight loss outcomes, focusing on how these relationships might influence energy balance in obese adolescents.

Sex differences in pulmonary oxygen uptake kinetics in obese adolescents.

OBJECTIVE: To determine whether sex differences exist in the pulmonary oxygen uptake (VO2) uptake on-kinetic response to moderate exercise in obese adolescents. We also examined whether a relationship existed between the VO2 on-transient response to moderate intensity exercise, steady-state VO2, and peak VO2 between obese male and female adolescents. STUDY DESIGN: Male (n = 12) and female (n = 28) adolescents completed a graded exercise test to exhaustion on a treadmill. Data from the initial 4 minutes of treadmill walking were used to determine the time constant. RESULTS: The time constant was significantly different (P = .001) between obese male and female adolescents (15.17 ± 8.45 seconds vs 23.07 ± 8.91 seconds, respectively). No significant relationships were observed between the time constant and variables of interest in either sex. CONCLUSIONS: Sex differences exist in VO2 uptake on-kinetics during moderate exercise in obese adolescents, indicating an enhanced potential for male subjects to deliver and/or use oxygen. It may be advantageous for female subjects to engage in a longer warm-up period before the initiation of an exercise regimen to prevent an early termination of the exercise session.