A Randomized Trial of Inspiratory Training in Children and Adolescents With Obesity

Introduction: Children with obesity suffer excess dyspnea that contributes to sedentariness. Developing innovative strategies to increase exercise tolerance and participation in children with obesity is a high priority. Because inspiratory training (IT) has reduced dyspnea, we sought to assess IT in children with obesity. Methods: We conducted a 6-week randomized IT trial involving 8- to 17-year-olds with obesity. Participants were randomized 1:1 to either high [75% of maximal inspiratory pressure (MIP)] or low resistance control (15% of MIP) three times weekly. Assessments included adherence, patient satisfaction, and changes in inspiratory strength and endurance, dyspnea scores and total activity level. Results: Among 27 randomized, 24 (89%) completed the intervention. Total session adherence was 72% which did not differ between treatment groups. IT was safe, and more than 90% felt IT benefitted breathing and general health. IT led to a mean improvement (95% CI) in inspiratory strength measured by MIP of 10.0 cm H2O (-3.5, 23.6; paired t-test, p = 0.139) and inspiratory endurance of 8.9 (1.0, 16.8; paired t-test, p = 0.028); however, there was no significant difference between high- and low-treatment groups. IT led to significant reductions in dyspnea with daily activity (p < 0.001) and in prospectively reported dyspnea during exercise (p = 0.024). Among the high- versus low-treatment group, we noted a trend for reduced dyspnea with daily activity (p = 0.071) and increased daily steps (865 vs. -51, p = 0.079). Discussion: IT is safe and feasible for children with obesity and holds promise for reducing dyspnea and improving healthy activity in children with obesity. Breathe-Fit trial NCT05412134.

Treadmill walking economy is not affected by body fat and body mass index in adults

To determine whether body fat and body mass index (BMI) affect the energy cost of walking (Cw; J/kg/m), ventilation, and gas exchange data from 205 adults (115 females; percent body fat range = 3.0%-52.8%; BMI range = 17.5-43.2 kg/m2) were obtained at rest and during treadmill walking at 1.34 m/s to calculate gross and net Cw. Linear regression was used to assess relationships between body composition indices, Cw, and standing metabolic rate (SMR). Unpaired t-tests were used to assess differences between sex, and one-way ANOVA was used to assess differences by BMI categories: normal weight, <25.0 kg/m2; overweight, 25.0-29.9 km/m2; and obese, ≥30 kg/m2. Net Cw was not related to body fat percent, fat mass, or BMI (all R2 ≤ 0.011). Furthermore, mean net Cw was similar by sex (male: 2.19 ± 0.30 J/kg/m; female: 2.24 ± 0.37 J/kg/m, p = 0.35) and across BMI categories (normal weight: 2.23 ± 0.36 J/kg/m; overweight: 2.18 ± 0.33 J/kg/m; obese: 2.26 ± 0.31, p = 0.54). Gross Cw and SMR were inversely associated with percent body fat, fat mass, and BMI (all R2 between 0.033 and 0.270; all p ≤ 0.008). In conclusion, Net Cw is not influenced by body fat percentage, total body fat, and BMI and does not differ by sex.

Body composition in early pubescent children with obesity: effects following 1 year of nonintervention

Little is known about whether body composition changes differently between children with and without obesity following 1 year of nonintervention. Therefore, we investigated body composition in early pubescent children (8-12 yr) with and without obesity before and after a period of 1 year of nonintervention. Early pubescent children (8-12 yr; Tanner stage ≤ 3) with (body mass index, BMI ≥ 95th percentile) and without obesity (15th < BMI < 85th percentile) were recruited. At baseline, 88 children (n = 25 without obesity) completed dual-energy X-ray absorptiometry imaging (DXA) for body composition measurements [%body fat, fat mass, fat-free mass (FFM)]. One year later, 47 participants (n = 15 without obesity) returned for repeat testing. The children without obesity were older (11.0 ± 1.0 vs. 10.0 ± 1.2 yr; means ± SD) (P = 0.013). There was no group difference in height, and both groups increased in height similarly after 1 year (147.7 ± 8.9 to 154.5 ± 9.2 cm without vs. 145.6 ± 5.8 to 152.5 ± 5.9 cm with obesity) (P < 0.001). Weight was greater (P < 0.001) in children with obesity at baseline as was the increase in weight after 1 yr (9.25 vs. 5.82 kg) (interaction, P = 0.005). Fat mass increased by 4.4 kg in children with obesity and by 1.1 kg in children without obesity (interaction, P < 0.001). However, there was no difference in fat-free mass between those with and without obesity at baseline (29.9 ± 5.9 vs. 31.6 ± 4.8 kg) (P = 0.206) with both groups increasing similarly over 1 year (gain of 4.87 vs. 4.85 kg with and without obesity, respectively). Without intervention, the increase in fat mass is four times greater in children with obesity after 1 year as compared with children without obesity.NEW & NOTEWORTHY Little is known about changes in body composition in children with and without obesity following 1 year of nonintervention. We report that without intervention, fat mass gain is significantly greater in children with obesity after 1 year compared with those without obesity. Body mass index (BMI) and %body fat measurements after 1 year yielded no significant increase suggesting that BMI and %fat alone are not suitable measures for tracking changes in adiposity among children.

The Effect of Body Armor on Pulmonary Function Using Plethysmography

Military tactical athletes face the unique task of performing physically demanding occupational duties, often while wearing body armor. Forced vital capacity and forced expiratory volume measured using spirometry have been shown to decrease, while wearing plate-carrier style body armor, little is known about the comprehensive effects of wearing body armor on pulmonary function, including lung capacities. Further, the effects of loaded body armor vs. unloaded on pulmonary function are also unknown. Therefore, this study examined how loaded and unloaded body armor affects pulmonary function. Twelve college-aged males performed spirometry and plethysmography under three conditions (basic athletic attire [CNTL], unloaded plate carrier [UNL], and loaded plate carrier [LOAD]). Compared to CNTL, LOAD and UNL conditions significantly reduced functional residual capacity by 14% and 17%, respectively. Compared with CNTL, LOAD condition also showed a small but statistically significant lowered forced vital capacity (P = .02, d = 0.3), a 6% lower total lung capacity (P < .01, d = 0.5), and lowered maximal voluntary ventilation (P = .04, d = 0.4). A loaded plate-carrier style body armor exerts a restrictive effect on total lung capacity, and both loaded and unloaded body armor affects functional residual capacity, which could impact breathing mechanics during exercise. Resulting endurance performance decreases may need to be factored based on the style and loading of body armor, especially for longer-duration operations.

Acute Effects of Albuterol on Ventilatory Capacity in Children with Asthma

BACKGROUND

Children with asthma may have a reduced ventilatory capacity, which could lead to symptoms and early termination of a cardiopulmonary exercise test (CPET). The purpose of this study was to examine the effects of short-acting beta agonist (albuterol) administration on estimated ventilatory capacity in children with asthma.

METHODS

Fifteen children (eleven boys, 10.6 ± 0.9 years) completed spirometry at baseline, after 180 µg of albuterol, and after the CPET in this cross-sectional study. Ventilatory capacity was calculated from forced vital capacity (FVC) and isovolume forced expiratory time from 25 to 75% of FVC (isoFET25-75) as follows: FVC/2 × [60/(2 × isoFET25-75)]. Differences in outcome variables between baseline, after albuterol administration, and after the CPET were detected with repeated measures mixed models with Bonferroni post hoc corrections.

RESULTS

Estimated ventilatory capacity was higher after albuterol (68.7 ± 21.2 L/min) and after the CPET (75.8 ± 25.6 L/min) when compared with baseline (60.9 ± 22.0 L/min; P = 0.003). Because forced vital capacity did not change, the increased ventilatory capacity was primarily due to a decrease in isoFET25-75 (i.e., an increase in mid-flows or isoFEF25-75).

CONCLUSION

Albuterol administration could be considered prior to CPET for children with asthma with relatively well-preserved FEV1 values to increase ventilatory capacity pre-exercise and potentially avoid symptom-limited early termination of testing.

Static respiratory mechanics are unaltered in males and females with obesity

We tested the hypothesis that independent of the obesity-related shift in lung volume subdivisions, obesity would not reduce the interrelationships of expiratory flow, lung volume, and static lung elastic recoil pressure in males and females. Simultaneous measurements of expiratory flow, volume, and transpulmonary pressure were continuously recorded while flow-volume loops of varying expiratory efforts were performed in a pressure-corrected, volume-displacement body plethysmograph in males and females with obesity. Static compliance curves were collected using the occlusion technique. Flow-volume, static pressure-volume, and static pressure-flow relationships were examined. Isovolume pressure-flow curves were constructed for the determination of the critical pressure for maximal flow. Data were compared with that collected in lean males and females. Individuals with obesity displayed a notable decrease in functional residual capacity. The interrelationships of flow, lung volume, static elastic recoil pressure, and the minimum pressure required for maximal expiratory flow in males and females with obesity were not different from that in lean males and females (all P > 0.05). Obesity does not alter the interrelationships of flow-volume-pressure of the lung in adult males and females (all P > 0.05). We further explored potential sex differences in static mechanics independent of obesity and observed that females have lower maximal expiratory flow due to a combination of smaller lungs and greater upstream flow resistance compared with males (all P ≤ 0.05).NEW & NOTEWORTHY The potential influence of obesity on the interrelationships between maximal expiratory flow, lung volume, and static lung elastic recoil pressure is unclear. These data show that the presence of obesity does not alter the relationship of flow and pressure across the mid-expiratory range in males and females. In addition, independent of obesity, females have smaller lungs and greater upstream flow resistance, which contributes to reduced maximal flow, when compared with males.

Mechanical effects of obesity on central and peripheral airway resistance in nonasthmatic early pubescent children

BACKGROUND

In children, obesity typically reduces functional residual capacity (FRC), which reduces airway caliber and increases airway resistance. Whether these obesity-related changes in respiratory function can alter bronchodilator responsiveness is unknown.

OBJECTIVE

To investigate bronchodilator responsiveness in nonasthmatic children with and without obesity.

METHODS

Seventy nonasthmatic children, 8-12 years old, without (n = 19) and with (n = 51) obesity, completed spirometry, impulse oscillometry, and airway resistance measurements through plethysmography pre/post 360 µg of inhaled albuterol. FRC was assessed pre albuterol. A two-way analysis of variance determined the effects of obesity (group) and inhaled albuterol (pre-post) on outcome measures.

RESULTS

FRC (%total lung capacity) was 16% lower in children with obesity compared with those without obesity. There was no significant group by pre-post albuterol interaction on any outcome variables. Albuterol inhalation reduced total, central and peripheral airway resistance and increased airway reactance (i.e., less negative) to a similar degree in children with and without obesity. In children with obesity, airway resistance was increased whether measured by impulse oscillometry or plethysmography. However, once airway resistance was adjusted for lung volumes (i.e., specific airway resistance or sRaw ), there were no differences between children with and without obesity. In addition, significant but moderate associations were detected between chest mass and FRC (r = -0.566; p < 0.001), FRC and total airway resistance (i.e., Raw ; r = -0.445; p < 0.001).

CONCLUSIONS

In nonasthmatic early pubescent children, obesity increases total, central, and peripheral respiratory system resistance. However, the added respiratory system resistance and low lung volume breathing with obesity are not sufficient to reduce bronchodilator responsiveness.

Sex differences in the ventilatory responses to exercise in mild-moderate obesity

NEW FINDINGS

What is the central question of the study? What are the sex differences in ventilatory responses during exercise in adults with obesity. What is the main finding and its importance? Tidal volume and expiratory flows are lower in females when compared with males at higher levels of ventilation despite small increases in end-expiratory lung volumes. Since dyspnea on exertion is a frequent complaint, particularly in females with obesity, careful attention should be paid to unpleasant respiratory symptoms and mechanical ventilatory constraints before prescribing exercise.

ABSTRACT

Obesity is associated with altered ventilatory responses, which may be exacerbated in females due to the functional consequences of sex-related morphological differences in the respiratory system. This study examined sex differences in ventilatory responses during exercise in adults with obesity. Healthy adults with obesity (n = 73; 48 females) underwent pulmonary function testing, underwater weighing, magnetic resonance imaging, a graded exercise test to exhaustion, and two constant work rate exercise tests; one at a fixed work rate (60W for females and 105W for males) and one at a relative intensity (50% of peak oxygen uptake, V̇O_2peak ). Metabolic, respiratory, and perceptual responses were assessed during exercise. Compared with males, females used a smaller proportion of their ventilatory capacity at peak exercise (69.13 ± 14.49 vs. 77.41 ± 17.06 % maximum voluntary ventilation, P = 0.0374). Females also utilized a smaller proportion of their forced vital capacity (FVC) at peak exercise (tidal volume: 48.51±9.29 vs. 54.12±10.43 %FVC, P = 0.0218). End-expiratory lung volumes were 2-4% higher in females compared with males during exercise (P<0.05), while end-inspiratory lung volumes were similar. Since the males were initiating inspiration from a lower lung volume, they experienced greater expiratory flow limitation during exercise. Ratings of perceived breathlessness during exercise were similar between females and males at comparable levels of ventilation. In summary, sex differences in the manifestations of obestity-related mechanical ventilatory constraints were observed. Since dyspnea on exertion is a common complaint in patients with obesity, particularly in females, exercise prescriptions should be tailored with the goal of minimizing unpleasant respiratory sensations. This article is protected by copyright. All rights reserved.

Repeatability of dyspnea measurements during exercise in women with obesity

While the 0-10 Borg scale to rate perceived breathlessness (RPB) is widely used to assess dyspnea on exertion, the repeatability of RPB in women with obesity is unknown. We examined the repeatability of RPB in women with obesity during submaximal constant-load cycling following at least 10 weeks of normal daily life. Seventeen women (37 ± 7 yr; 34.6 ± 4.5 kg/m²) who rated their breathlessness as 3 on the Borg scale (i.e., "moderate") during 60 W submaximal cycling repeated the same test following 19 ± 9 weeks of normal living. Mean body weight (93.8 ± 16.1 vs. 93.6 ± 116.8 kg, p = 0.94) and RPB (3.0 ± 0.0 vs. 3.1 ± 1.4, p = 0.80) did not differ between pre- and post-normal living periods. We demonstrate that subjective ratings of breathlessness are repeatable for the majority of subjects and can be used to accurately assess DOE during submaximal constant-load cycling in women with obesity.

Respiratory and Perceptual Responses to High-Intensity Interval Exercise in Obese Adults

PURPOSE

Although high-intensity interval exercise (HIIE) has emerged as an attractive alternative to continuous exercise (CE), the effects of HIIE on ventilatory constraints and dyspnea on exertion have not been studied in obese adults, and thus, tolerability of HIIE in obese adults is unknown. The purpose of this study was to examine differences in respiratory and perceptual responses between HIIE and CE in nonobese and obese adults.

METHODS

Ten nonobese (5 men; 24.1 ± 6.2 yr; body mass index, 23.0 ± 1.3 kg·m-2) and 10 obese (5 men; 24.2 ± 3.8 yr; body mass index, 37 ± 4.6 kg·m-2) adults participated in this study. Respiratory and perceptual responses were assessed during HIIE (eight 30-s intervals at 80% maximal work rate, with 45-s recovery periods) and two 6-min sessions of CE, completed below and above ventilatory threshold (Vth).

RESULTS

Despite similar work rate, HIIE was completed at a higher relative intensity in obese when compared with nonobese participants (68.8% ± 9.4% vs 58.9% ± 5.6% maximal oxygen uptake, respectively; P = 0.01). Expiratory flow limitation and/or dynamic hyperinflation was present during HIIE in 50% of the obese but in none of the nonobese participants. Ratings of perceived breathlessness were highest during HIIE (5.3 ± 2.4), followed by CEaboveVth (2.5 ± 1.6), and CEbelowVth (0.9 ± 0.7; P < 0.05) in obese participants. Unpleasantness associated with breathlessness was higher in obese (4.2 ± 3.0) when compared with nonobese participants (0.6 ± 1.3; P = 0.005) during HIIE.

CONCLUSIONS

HIIE, when prescribed relative to maximal work rate, is associated with greater ventilatory constraints and dyspnea on exertion when compared with CE in obese adults. CE may be more tolerable when compared with HIIE for obese adults.

Dysanapsis in men and women with obesity

Obesity alters chest wall mechanics, reduces lung volumes, and increases airway resistance. In addition, the luminal area of the larger conducting airways is smaller in women than in men when matched for lung size. We examined whether differences in pulmonary mechanics with obesity and sex were associated with the dysanapsis ratio (DR), an estimate of airway size when the expiratory flow is maximal, in men and women with and without obesity. In addition, we examined the ability to estimate DR using predicted versus measured static recoil pressure at 50% forced vital capacity (FVC; Pst_50FVC). Participants completed pulmonary function testing and measurements of pulmonary mechanics. Flow, volume, and transpulmonary pressure were recorded while completing forced vital capacity (FVC) maneuvers in a body plethysmograph. Static compliance curves were collected using the occlusion technique. DR was calculated using measured values of forced midexpiratory flow and Pst_50FVC. DR was also calculated using Pst predicted from previously reported data. There was no significant group (lean vs. obese) by sex interaction or main effect of group on DR. However, women displayed significantly larger DR compared with men. Predicted Pst_50FVC was significantly greater than measured Pst_50FVC. DR calculated from measured Pst was significantly greater than when using predicted Pst. In conclusion, although obesity does not appear to alter airway size, women may have larger airways compared with men when midexpiratory flow is maximal. In addition, DR estimated using predicted Pst should be used with caution.NEW & NOTEWORTHY It is unclear whether obesity in combination with sex influences the dysanapsis ratio (DR). These data indicate that DR is unaltered in adults with obesity and is greater in women than in men but similar between sexes when matched for lung volume. We also report a significant difference between predicted and measured static recoil pressure. Thus, we caution against predicting static recoil pressure in the calculation of DR.

Recruitment and Retention of Healthy Women with Obesity for a Psychophysiological Study before and After Weight Loss: Insights, Challenges, and Suggestions

OBJECTIVE

The objective of this paper is to present data on participant recruitment, retention, and weight loss success during a psychophysiological study in women with obesity.

METHODS

Volunteers were women with obesity, 20 - 45 yr, with a BMI between 30 - 45 kg/m². The study was approximately 20 weeks in duration, including a 12-week weight loss program.

RESULTS

Recruitment was not completed until 8 months past the original projected date of 12 months. The study was not completed until 11 months past the original projected completion date of 14 months. On average 4.4 ± 2.1 (mean ± SD) volunteers were consented per month (N = 99) and 2.5 ± 1.1 participants started the weight loss program per month. 24% of consented volunteers were lost due to exclusion criteria, withdrawals, and unresponsive behavior before starting the weight loss program. Attrition of participants who started the weight loss program was 45%. Only 11% of those who started the program were unable to lose weight (N = 6).

CONCLUSION

Recruiting and/or weight loss success do not always present the most challenging aspects of completing a psychophysiological weight loss intervention. While participant attrition during a weight loss program can occur for a wide range of reasons supportive efforts in the early phases of the intervention may maximize retention.

Inhaled albuterol increases estimated ventilatory capacity in nonasthmatic children without and with obesity

Forced mid-expiratory flow (i.e., isoFEF_25-75) may increase with a short-acting β₂-agonist in nonasthmatic children without bronchodilator responsiveness. This could also increase estimated ventilatory capacity along mid-expiration (V̇Ecap_25-75), especially in vulnerable children with obesity who exhibit altered breathing mechanics. We estimated V̇Ecap_25-75 pre- and post-albuterol treatment in 8-12yo children without (n = 28) and with (n = 46) obesity. A two-way ANOVA was performed to determine effects of an inhaled bronchodilator (pre-post) and obesity (group) on isoFEF_25-75 and V̇Ecap_25-75. There was no group by bronchodilator interaction or main group effect on outcome variables. However, a significant main effect of the bronchodilator was detected in spirometry parameters, including a substantial increase in isoFEF_25-75 (17.1 ± 18.0 %) and only a slight (non-clinical) but significant increase in FEV₁ (2.4 ± 4.3 %). V̇Ecap_25-75 significantly increased with albuterol (+11.7 ± 10.6 L/min; +15.8 ± 13.9 %). These findings imply potentially important increases in ventilatory reserve with a bronchodilator in nonasthmatic children without and with obesity, which could potentially influence respiratory function at rest and during exercise.

Effects of obesity on the oxygen cost of breathing in children

The objective of this study was to examine the effects of obesity on the oxygen (O₂) cost of breathing using the eucapnic voluntary hyperpnea (EVH) technique in 10- and 11-year-old children. Seventeen children (8 without and 9 with obesity) underwent EVH trials at two levels of ventilation for assessing the O₂ cost of breathing (slope of oxygen uptake, V˙O₂ vs. minute ventilation) and a dual energy x-ray absorptiometry scan. Resting and EVH V˙O₂ was higher in children with obesity when compared with children without obesity (P = 0.0096). The O₂ cost of breathing did not statistically differ between children without (2.09 ± 0.46 mL/L) and with obesity (2.08 ± 0.64 mL/L, P = 0.99), but the intercept was significantly greater in children with obesity. Chest mass explained 85 % of the variance in resting V˙O₂ in children with obesity. Higher resting energy requirements, attributable to increased chest mass, can increase the absolute metabolic costs of exercise and hyperpnea in children with obesity.

Pitfalls in Expiratory Flow Limitation Assessment at Peak Exercise in Children: Role of Thoracic Gas Compression

PURPOSE

Thoracic gas compression and exercise-induced bronchodilation can influence the assessment of expiratory flow limitation (EFL) during cardiopulmonary exercise tests. The purpose of this study was to examine the effect of thoracic gas compression and exercise-induced bronchodilation on the assessment of EFL in children with and without obesity.

METHODS

Forty children (10.7 ± 1.0 yr; 27 obese; 15 with EFL) completed pulmonary function tests and incremental exercise tests. Inspiratory capacity maneuvers were performed during the incremental exercise test for the placement of tidal flow volume loops within the maximal expiratory flow volume (MEFV) loops, and EFL was calculated as the overlap between the tidal and the MEFV loops. MEFV loops were plotted with volume measured at the lung using plethysmography (MEFVp), with volume measured at the mouth using spirometry concurrent with measurements in the plethysmograph (MEFVm), and from spirometry before (MEFVpre) and after (MEFVpost) the incremental exercise test. Only the MEFVp loops were corrected for thoracic gas compression.

RESULTS

Not correcting for thoracic gas compression resulted in incorrect diagnosis of EFL in 23% of children at peak exercise. EFL was 26% ± 15% VT higher for MEFVm compared with MEFVp (P < 0.001), with no differences between children with and without obesity (P = 0.833). The difference in EFL estimation using MEFVpre (37% ± 30% VT) and MEFVpost (31% ± 26% VT) did not reach statistical significance (P = 0.346).

CONCLUSIONS

Not correcting the MEFV loops for thoracic gas compression leads to the overdiagnosis and overestimation of EFL. Because most commercially available metabolic measurement systems do not correct for thoracic gas compression during spirometry, there may be a significant overdiagnosis of EFL in cardiopulmonary exercise testing. Therefore, clinicians must exercise caution while interpreting EFL when the MEFV loop is derived through spirometry.

External dead space explains sex-differences in the ventilatory response to submaximal exercise in children with and without obesity

We compared the exercise ventilatory response (slope of the ventilation, V̇_E and carbon dioxide production, V̇CO₂ relationship) in boys and girls with and without obesity. 46 children with obesity (BMI percentile: 97.7 ± 1.4) and 27 children without obesity (BMI percentile: 55.1 ± 22.2) were included and divided into groups by sex (with obesity: 17 girls and 29 boys; without obesity: 13 girls and 14 boys). A 6 min constant load cycling test at 45 % of peak work rate was performed. The V̇_E/V̇CO₂ slope was similar (p = 0.67) between children with (32.7 ± 4.3) and without (32.2 ± 6.1) obesity; however, it was higher (p = 0.02) in girls (35.4 ± 5.6) than boys (32.6 ± 4.9). We also examined a corrected V̇_E/V̇CO₂ slope for the effects of mechanical dead space (V_DM), by subtracting V̇_DM from V̇_E (V̇_Ecorr/V̇CO₂ slope). The V̇_Ecorr/V̇CO₂ slope remained similar (p = 0.37) between children with (26.8 ± 3.2) and without obesity (26.1 ± 3.1); however, no sex differences were observed (p = 0.13). Therefore, V_DM should be accounted for before evaluating the V̇_E/V̇CO₂ slope, particularly when making between-sex comparisons.

Quantification of Cardiorespiratory Fitness in Children with Obesity

PURPOSE

Without consideration for the effects of fat mass, there could be an underestimation of cardiorespiratory fitness in children with obesity leading to a clinical diagnosis of deconditioning and resulting in unrealistic training goals and limitation of physical activities. The purpose of this study was to identify methods of quantifying cardiorespiratory fitness that were less influenced by fat mass.

METHODS

Fifty-three children, 27 with obesity (10.9 ± 1.0 yr) and 26 without obesity (11.0 ± 1.0 yr), volunteered for this study. Maximal oxygen uptake, an indicator of cardiorespiratory fitness, was referenced to lean body mass, body mass, and predicted body mass at the 50th and 85th body mass index percentiles.

RESULTS

Children with obesity carried 18 kg more fat mass and 7 kg more lean body mass compared with children without obesity. Cardiorespiratory fitness based on lean body mass, body mass, and predicted body mass at the 85th percentile was lower in children with obesity compared with children without obesity (P < 0.001). Differences in cardiorespiratory fitness based on predicted body mass at the 50th percentile between children with and without obesity did not reach statistical significance (P = 0.84). Fat mass influenced cardiorespiratory fitness least when referenced to lean body mass or predicted body mass at the 50th percentile (R < 0.26) in contrast to when it was referenced to body mass or predicted body mass at the 85th percentile (R > 0.37).

CONCLUSION

Quantifying cardiorespiratory fitness based on lean body mass or predicted body mass at the 50th percentile could be useful for estimating fitness levels in children with obesity.

Weight loss reduces dyspnea on exertion and unpleasantness of dyspnea in obese men

We hypothesized that weight loss would ameliorate dyspnea on exertion (DOE) and feelings of unpleasantness related to the DOE in obese men. Eighteen men (34 ± 7yr, 35 ± 4 kg/m2 BMI, mean ± SD) participated in a 12-week weight loss program. Body composition, pulmonary function, cardiorespiratory measures, DOE, and unpleasantness (visual analog scale) were assessed before and after weight loss. Subjects were grouped by Ratings of Perceived Breathlessness (RPB, Borg 0-10 scale) during submaximal cycling: Ten men rated RPB ≥ 4 (+DOE), eight rated RPB ≤ 2 (-DOE). Subjects lost 10.3 ± 5.6 kg (9.2 ± 4.5%) of body weight (n = 18). RPB during submaximal cycling was significantly improved in both groups (+DOE: 4.1 ± 0.3-2.8 ± 1.1; -DOE: 1.3 ± 0.7 to 0.8 ± 0.6, p < 0.001). Several submaximal exercise variables (e.g., V˙O2, V˙E) were decreased similarly in both groups (p < 0.01). Unpleasantness associated with the DOE was reduced (p < 0.05). The improved RPB was not significantly correlated with changes in body weight or cardiopulmonary exercise responses (p > 0.05). Moderate weight loss appears to be an effective option to ameliorate DOE and unpleasantness related to DOE in obese men.

Dyspnea on exertion provokes unpleasantness and negative emotions in women with obesity

PURPOSE

While dyspnea on exertion (DOE) is a common complaint in otherwise healthy obese women, less is known about feelings of unpleasantness and/or negative emotions provoked by DOE. We examined whether ratings of perceived breathlessness (RPB) during exercise were associated with ratings of unpleasantness and negative emotions (depression, anxiety, frustration, anger, and fear) in obese women.

METHODS

Seventy-four women (34 ± 7 yrs, 36 ± 4 kg/m², 46 ± 5% body fat) performed 6 min of constant-load cycling (60 W); RPB (0-10 scale), and unpleasantness and negative emotions (visual analog scales, 10 cm) were assessed at the end.

RESULTS

RPB were significantly correlated with unpleasantness and negative emotions (p < 0.05). The strongest correlations were between RPB and unpleasantness (r = 0.61, p < 0.001), and RPB and anxiety (r = 0.50, p < 0.001).

CONCLUSIONS

DOE can significantly provoke unpleasantness and negative emotions during exercise in obese women. This may affect their willingness to engage in regular physical activity.

Breaks in Sitting Time: Effects on Continuously Monitored Glucose and Blood Pressure

PURPOSE

We examined the effects of interrupting prolonged sitting with multiple 2-min walking breaks or one 30-min continuous walking session on glucose control and ambulatory blood pressure (ABP).

METHODS

Ten overweight/obese, physically inactive participants (five men; 32 ± 5 yr; BMI, 30.3 ± 4.6 kg·m) participated in this randomized four-trial crossover study, with each trial performed on a separate, simulated workday lasting 9 h: 1) 30 min of continuous moderate-intensity (30-min MOD) walking at 71% ± 4% HRmax; 2) 21 × 2 min bouts of moderate-intensity (2-min MOD) walking at 53% ± 5% HRmax, each performed every 20 min (42 min total); 3) 8 × 2 min bouts of vigorous-intensity (2-min VIG) walking at 79% ± 4% HRmax, each performed every hour (16 min total); 4) 9 h of prolonged sitting (SIT). Participants underwent continuous interstitial glucose monitoring and ABP monitoring during and after the simulated workday spent in the laboratory, with primary data analysis from 12:30 h to 07:00 h the next morning.

RESULTS

Compared with SIT (5.6 ± 1.1 mmol·L), mean 18.7-h glucose was lower during the 2-min MOD (5.2 ± 1.1 mmol·L) and 2-min VIG (5.4 ± 0.9 mmol·L) trials and mean 18.7-h glucose during the 30-min MOD trial (5.1 ± 0.8 mmol·L) was lower than all other trials (P < 0.001). Postprandial glucose was approximately 7% to 13% lower during all trials compared with SIT (P < 0.001), with 30-min MOD having the greatest effect. Only the 30-min MOD trial was effective in reducing systolic ABP from 12:30 to 07:00 h (119 ± 15 mm Hg) when compared with SIT (122 ± 16 mm Hg; P < 0.05).

CONCLUSIONS

Replacing sitting with 2-min MOD walking every 20 min or 2 min of vigorous-intensity walking every hour during a simulated workday reduced 18.7 h and postprandial glucose, but only 30-min MOD walking was effective for reducing both glucose and systolic ABP.

Verification of Maximal Oxygen Uptake in Obese and Nonobese Children

PURPOSE

The purpose of this study was to examine whether a supramaximal constant-load verification test at 105% of the highest work rate would yield a higher V˙O2max when compared with an incremental test in 10- to 12-yr-old nonobese and obese children.

METHODS

Nine nonobese (body mass index percentile = 57.5 ± 23.2) and nine obese (body mass index percentile = 97.9 ± 1.4) children completed a two-test protocol that included an incremental test followed 15 min later by a supramaximal constant-load verification test.

RESULTS

The V˙O2max achieved in verification testing (nonobese = 1.71 ± 0.31 L·min and obese = 1.94 ± 0.47 L·min) was significantly higher than that achieved during the incremental test (nonobese = 1.57 ± 0.27 L·min and obese = 1.84 ± 0.48 L·min; P < 0.001). There was no significant group (i.e., nonobese vs obese)-test (i.e., incremental vs verification) interaction, suggesting that there was no effect of obesity on the difference between verification and incremental V˙O2max (P = 0.747).

CONCLUSION

A verification test yielded significantly higher values of V˙O2max when compared with the incremental test in obese children. Similar results were observed in nonobese children. Supramaximal constant-load verification is a time-efficient and well-tolerated method for identifying the highest V˙O2 in nonobese and obese children.

Cycling efficiency and energy cost of walking in young and older adults

To determine whether age affects cycling efficiency and the energy cost of walking (Cw), 190 healthy adults, ages 18-81 yr, cycled on an ergometer at 50 W and walked on a treadmill at 1.34 m/s. Ventilation and gas exchange at rest and during exercise were used to calculate net Cw and net efficiency of cycling. Compared with the 18-40 yr age group (2.17 ± 0.33 J·kg^-1·m^-1), net Cw was not different in the 60-64 yr (2.20 ± 0.40 J·kg^-1·m^-1) and 65-69 yr (2.20 ± 0.28 J·kg^-1·m^-1) age groups, but was significantly ( P < 0.03) higher in the ≥70 yr (2.37 ± 0.33 J·kg^-1·m^-1) age group. For subjects >60 yr, net Cw was significantly correlated with age ( R² = 0.123; P = 0.002). Cycling net efficiency was not different between 18-40 yr (23.5 ± 2.9%), 60-64 yr (24.5 ± 3.6%), 65-69 yr (23.3 ± 3.6%) and ≥70 yr (24.7 ± 2.7%) age groups. Repeat tests on a subset of subjects (walking, n = 43; cycling, n = 37) demonstrated high test-retest reliability [intraclass correlation coefficients (ICC), 0.74-0.86] for all energy outcome measures except cycling net energy expenditure (ICC = 0.54) and net efficiency (ICC = 0.50). Coefficients of variation for all variables ranged from 3.1 to 7.7%. Considerable individual variation in Cw and efficiency was evident, with a ~2-fold difference between the least and most economical/efficient subjects. We conclude that, between 18 and 81 yr, net Cw was only higher for ages ≥70 yr, and that cycling net efficiency was not different across age groups. NEW & NOTEWORTHY This study illustrates that the higher energy cost of walking in older adults is only evident for ages ≥70 yr. For older adults ages 60-69 yr, the energy cost of walking is similar to that of young adults. Cycling efficiency, by contrast, is not different across age groups. Considerable individual variation (∼2-fold) in cycling efficiency and energy cost of walking is observed in young and older adults.

High-intensity interval exercise attenuates but does not eliminate endothelial dysfunction after a fast food meal

We investigated whether two different bouts of high-intensity interval exercise (HIIE) could attenuate postprandial endothelial dysfunction. Thirteen young (27 ± 1 yr), nonexercise-trained men underwent three randomized conditions: 1) four 4-min intervals at 85-95% of maximum heart rate separated by 3 min of active recovery (HIIE 4 × 4), 2) 16 1-min intervals at 85-95% of maximum heart rate separated by 1 min of active recovery (HIIE 16 × 1), and 3) sedentary control. HIIE was performed in the afternoon, ~18 h before the morning fast food meal (1,250 kcal, 63g of fat). Brachial artery flow-mediated dilation (FMD) was performed before HIIE ( baseline 1), during fasting before meal ingestion ( baseline 2), and 30 min, 2 h, and 4 h postprandial. Capillary glucose and triglycerides were assessed at fasting, 30 min, 1 h, 2 h, and 4 h (triglycerides only). Both HIIE protocols increased fasting FMD compared with control (HIIE 4 × 4: 6.1 ± 0.4%, HIIE 16 × 1: 6.3 ± 0.5%, and control: 5.1 ± 0.4%, P < 0.001). For both HIIE protocols, FMD was reduced only at 30 min postprandial but never fell below baseline 1 or FMD during control at any time point. In contrast, control FMD decreased at 2 h (3.8 ± 0.4%, P < 0.001) and remained significantly lower than HIIE 4 × 4 and 16 × 1 at 2 and 4 h. Postprandial glucose and triglycerides were unaffected by HIIE. In conclusion, HIIE performed ~18 h before a high-energy fast food meal can attenuate but not entirely eliminate postprandial decreases in FMD. This effect is not dependent on reductions in postprandial lipemia or glycemia. NEW & NOTEWORTHY Two similar high-intensity interval exercise (HIIE) protocols performed ∼18 h before ingestion of a high-energy fast food meal attenuated but did not entirely eliminate postprandial endothelial dysfunction in young men largely by improving fasting endothelial function. Both HIIE protocols produced essentially identical results, suggesting high reproducibility of HIIE effects.

Validity of SenseWear® Armband v5.2 and v2.2 for estimating energy expenditure

We compared SenseWear Armband versions (v) 2.2 and 5.2 for estimating energy expenditure in healthy adults. Thirty-four adults (26 women), 30.1 ± 8.7 years old, performed two trials that included light-, moderate- and vigorous-intensity activities: (1) structured routine: seven activities performed for 8-min each, with 4-min of rest between activities; (2) semi-structured routine: 12 activities performed for 5-min each, with no rest between activities. Energy expenditure was measured by indirect calorimetry and predicted using SenseWear v2.2 and v5.2. Compared to indirect calorimetry (297.8 ± 54.2 kcal), the total energy expenditure was overestimated (P < 0.05) by both SenseWear v2.2 (355.6 ± 64.3 kcal) and v5.2 (342.6 ± 63.8 kcal) during the structured routine. During the semi-structured routine, the total energy expenditure for SenseWear v5.2 (275.2 ± 63.0 kcal) was not different than indirect calorimetry (262.8 ± 52.9 kcal), and both were lower (P < 0.05) than v2.2 (312.2 ± 74.5 kcal). The average mean absolute per cent error was lower for the SenseWear v5.2 than for v2.2 (P < 0.001). SenseWear v5.2 improved energy expenditure estimation for some activities (sweeping, loading/unloading boxes, walking), but produced larger errors for others (cycling, rowing). Although both algorithms overestimated energy expenditure as well as time spent in moderate-intensity physical activity (P < 0.05), v5.2 offered better estimates than v2.2.

Physiological Responses to High-Intensity Interval Exercise Differing in Interval Duration

We determined the oxygen uptake (V[Combining Dot Above]O2), heart rate (HR), and blood lactate responses to 2 high-intensity interval exercise protocols differing in interval length. On separate days, 14 recreationally active males performed a 4 × 4 (four 4-minute intervals at 90-95% HRpeak, separated by 3-minute recovery at 50 W) and 16 × 1 (sixteen 1-minute intervals at 90-95% HRpeak, separated by 1-minute recovery at 50 W) protocol on a cycle ergometer. The 4 × 4 elicited a higher mean V[Combining Dot Above]O2 (2.44 ± 0.4 vs. 2.36 ± 0.4 L·min) and "peak" V[Combining Dot Above]O2 (90-99% vs. 76-85% V[Combining Dot Above]O2peak) and HR (95-98% HRpeak vs. 81-95% HRpeak) during the high-intensity intervals. Average power maintained was higher for the 16 × 1 (241 ± 45 vs. 204 ± 37 W), and recovery interval V[Combining Dot Above]O2 and HR were higher during the 16 × 1. No differences were observed for blood lactate concentrations at the midpoint (12.1 ± 2.2 vs. 10.8 ± 3.1 mmol·L) and end (10.6 ± 1.5 vs. 10.6 ± 2.4 mmol·L) of the protocols or ratings of perceived exertion (7.0 ± 1.6 vs. 7.0 ± 1.4) and Physical Activity Enjoyment Scale scores (91 ± 15 vs. 93 ± 12). Despite a 4-fold difference in interval duration that produced greater between-interval transitions in V[Combining Dot Above]O2 and HR and slightly higher mean V[Combining Dot Above]O2 during the 4 × 4, mean HR during each protocol was the same, and both protocols were rated similarly for perceived exertion and enjoyment. The major difference was that power output had to be reduced during the 4 × 4 protocol to maintain the desired HR.

Using a Verification Test for Determination of V[Combining Dot Above]O2max in Sedentary Adults With Obesity

A constant-load exercise bout to exhaustion after a graded exercise test to verify maximal oxygen uptake (V[Combining Dot Above]O2max) during cycle ergometry has not been evaluated in sedentary adults with obesity. Nineteen sedentary men (n = 10) and women (n = 9) with obesity (age = 35.8 ± 8.6 years; body mass index [BMI] = 35.9 ± 5.1 kg·m; body fat percentage = 44.9 ± 7.2) performed a ramp-style maximal exercise test (ramp), followed by 5-10 minutes of active recovery, and then performed a constant-load exercise bout to exhaustion (verification test) on a cycle ergometer for determination of V[Combining Dot Above]O2max and maximal heart rate (HRmax). V[Combining Dot Above]O2max did not differ between tests (ramp: 2.29 ± 0.71 L·min, verification: 2.34 ± 0.67 L·min; p = 0.38). Maximal heart rate was higher on the verification test (177 ± 13 b·min vs. 174 ± 16 b·min; p = 0.03). Thirteen subjects achieved a V[Combining Dot Above]O2max during the verification test that was ≥2% (range: 2.0-21.0%; 0.04-0.47 L·min) higher than during the ramp test, and 8 subjects achieved a HRmax during the verification test that was 4-14 b·min higher than during the ramp test. Duration of verification or ramp tests did not affect V[Combining Dot Above]O2max results, but the difference in HRmax between the tests was inversely correlated with ramp test duration (r = -0.57, p = 0.01). For both V[Combining Dot Above]O2max and HRmax, differences between ramp and verification tests were not correlated with BMI or body fat percentage. A verification test may be useful for identifying the highest V[Combining Dot Above]O2max and HRmax during cycle ergometry in sedentary adults with obesity.

Postexercise Hypotension After Continuous, Aerobic Interval, and Sprint Interval Exercise

We examined the effects of 3 exercise bouts, differing markedly in intensity, on postexercise hypotension (PEH). Eleven young adults (age: 24.6 ± 3.7 years) completed 4 randomly assigned experimental conditions: (a) control, (b) 30-minute steady-state exercise (SSE) at 75-80% maximum heart rate (HRmax), (4) aerobic interval exercise (AIE): four 4-minute bouts at 90-95% HRmax, separated by 3 minutes of active recovery, and (d) sprint interval exercise (SIE): six 30-second Wingate sprints, separated by 4 minutes of active recovery. Exercise was performed on a cycle ergometer. Blood pressure (BP) was measured before exercise and every 15-minute postexercise for 3 hours. Linear mixed models were used to compare BP between trials. During the 3-hour postexercise, systolic BP (SBP) was lower (p < 0.001) after AIE (118 ± 10 mm Hg), SSE (121 ± 10 mm Hg), and SIE (121 ± 11 mm Hg) compared with control (124 ± 8 mm Hg). Diastolic BP (DBP) was also lower (p < 0.001) after AIE (66 ± 7 mm Hg), SSE (69 ± 6 mm Hg), and SIE (68 ± 8 mm Hg) compared with control (71 ± 7 mm Hg). Only AIE resulted in sustained (>2 hours) PEH, with SBP (120 ± 9 mm Hg) and DBP (68 ± 7 mm Hg) during the third-hour postexercise being lower (p ≤ 0.05) than control (124 ± 8 and 70 ± 7 mm Hg). Although all exercise bouts produced similar reductions in BP at 1-hour postexercise, the duration of PEH was greatest after AIE.

Effects of high-intensity interval training and moderate-intensity continuous training on endothelial function and cardiometabolic risk markers in obese adults

We hypothesized that high-intensity interval training (HIIT) would be more effective than moderate-intensity continuous training (MICT) at improving endothelial function and maximum oxygen uptake (V̇o2 max) in obese adults. Eighteen participants [35.1 ± 8.1 (SD) yr; body mass index = 36.0 ± 5.0 kg/m(2)] were randomized to 8 wk (3 sessions/wk) of either HIIT [10 × 1 min, 90-95% maximum heart rate (HRmax), 1-min active recovery] or MICT (30 min, 70-75% HRmax). Brachial artery flow-mediated dilation (FMD) increased after HIIT (5.13 ± 2.80% vs. 8.98 ± 2.86%, P = 0.02) but not after MICT (5.23 ± 2.82% vs. 3.05 ± 2.76%, P = 0.16). Resting artery diameter increased after MICT (3.68 ± 0.58 mm vs. 3.86 ± 0.58 mm, P = 0.02) but not after HIIT (4.04 ± 0.70 mm vs. 4.09 ± 0.70 mm; P = 0.63). There was a significant (P = 0.02) group × time interaction in low flow-mediated constriction (L-FMC) between MICT (0.63 ± 2.00% vs. -2.79 ± 3.20%; P = 0.03) and HIIT (-1.04 ± 4.09% vs. 1.74 ± 3.46%; P = 0.29). V̇o2 max increased (P < 0.01) similarly after HIIT (2.19 ± 0.65 l/min vs. 2.64 ± 0.88 l/min) and MICT (2.24 ± 0.48 l/min vs. 2.55 ± 0.61 l/min). Biomarkers of cardiovascular risk and endothelial function were unchanged. HIIT and MICT produced different vascular adaptations in obese adults, with HIIT improving FMD and MICT increasing resting artery diameter and enhancing L-FMC. HIIT required 27.5% less total exercise time and ∼25% less energy expenditure than MICT.

Effect of weight loss on operational lung volumes and oxygen cost of breathing in obese women

BACKGROUND

The effects of moderate weight loss on operational lung volumes during exercise and the oxygen (O2) cost of breathing are unknown in obese women but could have important implications regarding exercise endurance.

METHODS

In 29 obese women (33±8 years, 97±14 kg, body mass index: 36±4 kg m(-2), body fat: 45.6±4.5%; means±s.d.), body composition, fat distribution (by magnetic resonance imaging), pulmonary function, operational lung volumes during exercise and the O2 cost of breathing during eucapnic voluntary hyperpnea (([Vdot ]O2) vs ([Vdot ]E) slope) were studied before and after a 12-week diet and resistance exercise weight loss program.

RESULTS

Participants lost 7.5±3.1 kg or ≈8% of body weight (P<0.001), but fat distribution remained unchanged. After weight loss, lung volume subdivisions at rest were increased (P<0.05) and were moderately associated (P<0.05) with changes in weight. End-expiratory lung volume (percentage of total lung capacity) increased at rest and during constant load exercise (P<0.05). O2 cost of breathing was reduced by 16% (2.52±1.02-2.11±0.72 ml l(-1); P=0.003). As a result, O2 uptake of the respiratory muscles ([Vdot ]O2Resp), estimated as the product of O2 cost of breathing and exercise ([Vdot ]E) during cycling at 60 W, was significantly reduced by 27±31 ml (P<0.001), accounting for 46% of the reduction in total body ([Vdot ]O2) during cycling at 60 W.

CONCLUSIONS

Moderate weight loss yields important improvements in respiratory function at rest and during submaximal exercise in otherwise healthy obese women. These changes in breathing load could have positive effects on the exercise endurance and adherence to physical activity.

Predictors of fat mass changes in response to aerobic exercise training in women

Aerobic exercise training in women typically results in minimal fat loss, with considerable individual variability. We hypothesized that women with higher baseline body fat would lose more body fat in response to exercise training and that early fat loss would predict final fat loss. Eighty-one sedentary premenopausal women (age: 30.7 ± 7.8 years; height: 164.5 ± 7.4 cm; weight: 68.2 ± 16.4 kg; fat percent: 38.1 ± 8.8) underwent dual-energy x-ray absorptiometry before and after 12 weeks of supervised treadmill walking 3 days per week for 30 minutes at 70% of (Equation is included in full-text article.). Overall, women did not lose body weight or fat mass. However, considerable individual variability was observed for changes in body weight (-11.7 to +4.8 kg) and fat mass (-11.8 to +3.7 kg). Fifty-five women were classified as compensators and, as a group, gained fat mass (25.6 ± 11.1 kg to 26.1 ± 11.3 kg; p < 0.001). The strongest correlates of change in body fat at 12 weeks were change in body weight (r = 0.52) and fat mass (r = 0.48) at 4 weeks. Stepwise regression analysis that included change in body weight and body fat at 4 weeks and submaximal exercise energy expenditure yielded a prediction model that explained 37% of the variance in fat mass change (R = 0.37, p < 0.001). Change in body weight and fat mass at 4 weeks were moderate predictors of fat loss and may potentially be useful for identification of individuals who achieve less than expected weight loss or experience unintended fat gain in response to exercise training.

Aerobic exercise training without weight loss reduces dyspnea on exertion in obese women

Dyspnea on exertion (DOE) is a common symptom in obesity. We investigated whether aerobic exercise training without weight loss could reduce DOE. Twenty-two otherwise healthy obese women participated in a 12-week supervised aerobic exercise training program, exercising 30 min/day at 70-80% heart rate reserve, 4 days/week. Subjects were grouped based on their Ratings of Perceived Breathlessness (RPB) during constant load 60 W cycling: +DOE (n=12, RPB≥4, 37±7 years, 34±4 kg/m(2)) and -DOE (n=10, RPB≤2, 32±6 years, 33±3 kg/m(2)). No significant differences between the groups in body composition, pulmonary function, or cardiorespiratory fitness were observed pre-training. Post-training,peak was improved significantly in both groups (+DOE: 12±7, -DOE: 14±8%). RPB was significantly decreased in the +DOE (4.7±1.0-2.5±1.0) and remained low in the -DOE group (1.2±0.6-1.3±1.0) (interaction p<0.001). The reduction in RPB was not significantly correlated with the improvement in cardiorespiratory fitness. Aerobic exercise training improved cardiorespiratory fitness and DOE and thus appears to be an effective treatment for DOE in obese women.

Validity and reliability of Nike + Fuelband for estimating physical activity energy expenditure

Background

The Nike + Fuelband is a commercially available, wrist-worn accelerometer used to track physical activity energy expenditure (PAEE) during exercise. However, validation studies assessing the accuracy of this device for estimating PAEE are lacking. Therefore, this study examined the validity and reliability of the Nike + Fuelband for estimating PAEE during physical activity in young adults. Secondarily, we compared PAEE estimation of the Nike + Fuelband with the previously validated SenseWear Armband (SWA).

Methods

Twenty-four participants (n = 24) completed two, 60-min semi-structured routines consisting of sedentary/light-intensity, moderate-intensity, and vigorous-intensity physical activity. Participants wore a Nike + Fuelband and SWA, while oxygen uptake was measured continuously with an Oxycon Mobile (OM) metabolic measurement system (criterion).

Results

The Nike + Fuelband (ICC = 0.77) and SWA (ICC = 0.61) both demonstrated moderate to good validity. PAEE estimates provided by the Nike + Fuelband (246 ± 67 kcal) and SWA (238 ± 57 kcal) were not statistically different than OM (243 ± 67 kcal). Both devices also displayed similar mean absolute percent errors for PAEE estimates (Nike + Fuelband = 16 ± 13 %; SWA = 18 ± 18 %). Test-retest reliability for PAEE indicated good stability for Nike + Fuelband (ICC = 0.96) and SWA (ICC = 0.90).

Conclusion

The Nike + Fuelband provided valid and reliable estimates of PAEE, that are similar to the previously validated SWA, during a routine that included approximately equal amounts of sedentary/light-, moderate- and vigorous-intensity physical activity.