Lower than predicted resting metabolic rate is associated with severely impaired cardiorespiratory fitness in obese individuals

Obese individuals have reduced cardiorespiratory fitness as compared with leaner counterparts. Regular exercise maintains or increases fitness and lean body mass. Lean body mass, in turn, has a direct impact on resting metabolic rate (RMR). Given these relationships, we sought to evaluate the association between RMR and cardiorespiratory fitness in obese individuals. We evaluated 64 obese individuals (78% female) with direct assessment of RMR and cardiorespiratory fitness via breath‐by‐breath measurement of oxygen consumption and carbon dioxide production at rest and during exercise. The mean age and BMI were 47.4 ± 12.2 years and 47.2 ± 9.2 kg/m², respectively. The majority of subjects, 69%, had a measured RMR above that predicted by the Harris‐Benedict equation. Compared with the higher RMR group, those with a lower than predicted RMR had increased BMI, with values of 52.9 vs. 44.7 kg/m², P = 0.001, respectively. Analysis of those demonstrating significant effort during cardiopulmonary exercise testing (peak respiratory exchange ratio ≥1.10) revealed a significantly higher peak oxygen uptake (VO₂ peak) in the higher RMR group (17.3 ± 3.5 ml/min/kg) compared with the lower RMR group (13.6 ± 1.9 ml/min/kg), P = 0.003. In summary, a lower than predicted RMR was associated with a severely reduced VO₂ peak and a higher BMI in this cohort. These data suggest that morbid obesity may be a vicious cycle of increasing BMI, reduced cardiorespiratory fitness, muscle deconditioning, and lower RMR. Collectively, these responses may, over time, exacerbate the imbalance between energy intake and expenditure, resulting in progressive increases in body weight and fat stores.     

Effects of aerobic exercise on metabolic syndrome improvement in response to weight reduction

Objective: The objective was to test effects of aerobic exercise training on metabolic syndrome (MetSyn) improvement in response to weight reduction. Research Methods and Procedures: A total of 459 overweight and obese women (age, 49 ± 9 years; BMI, 28 ± 3 kg/m²) were recruited for a baseline examination to test the relationship between cardiorespiratory fitness and metabolic syndrome prevalence; among these, 67 subjects with MetSyn were treated with 14‐week weight‐loss programs, which included low‐calorie diet and aerobic exercise. The MetSyn was defined according to the Examination Committee of Criteria for “Metabolic Syndrome” in Japan. Maximal oxygen uptake (V?o _2max) during a maximal cycling test was measured as an index of cardiorespiratory fitness at baseline and after the intervention. Results: In the baseline examination, age‐ and BMI‐adjusted odds ratios for MetSyn prevalence in the low, middle, and upper thirds of V?o _2max were 1.0 (referent), 0.50 (95% confidence interval, 0.26 to 0.95), and 0.39 (95% confidence interval, 0.14 to 0.96), respectively (linear trend, p = 0.02). The adjusted odds ratios for MetSyn improvement in the two interventions with diet alone and diet plus exercise were 1.0 and 3.68 (95% confidence interval, 1.02 to 17.6; p = 0.04), respectively. Discussion: These results suggest that adding aerobic exercise training to a dietary weight‐reduction program further improves MetSyn (adjusted odds ratio, 3.68) in obese women, compared with diet alone. Further studies on an association between V?o _2max change and MetSyn improvement are needed.     

Dose-dependent effects of training and detraining on weight in 6406 runners during 7.4 years

Objective: Prior randomized and non‐randomized training studies have failed to establish a dose‐response relationship between vigorous exercise and weight loss; this failure may be due, in part, to their short durations and small sample sizes. The objectives of this study were to determine whether exercise reduces body weight and to examine the dose‐response relationships between changes in exercise and changes in total and regional adiposity. Research Methods and Procedures: This was a large prospective study of 3973 men and 1444 women who quit running (detraining), 270 men and 146 women who started running (training), and 420 men and 153 women who remained sedentary during 7.4 years of follow‐up. The outcomes measured were weekly running distance, body weight, BMI, body circumferences, and bra cup size. Results: There were significant inverse relationships between the changes in the amount of vigorous exercise (km/wk run) and the changes in weight and BMI in men (slope ± standard error: ?0.039 ± 0.005 kg/km per week and ?0.012 ± 0.002 kg/m² per km/wk, respectively) and in older women (?0.060 ± 0.018 kg/km per week and ?0.022 ± 0.007 kg/m² per km/wk) who quit running, and in initially sedentary men (?0.098 ± 0.017 kg/km per week and ?0.032 ± 0.005 kg/m² per km/wk) and women (?0.062 ± 0.023 kg/km per week and ?0.021 ± 0.008 kg/m² per km/wk) who started running. Changes in waist circumference, an indicator of intra‐abdominal fat, were also inversely related to changes in running distance in men who quit (?0.026 ± 0.005 cm/km per week) or started running (?0.078 ± 0.017 cm/km per week). Discussion: The initiation of vigorous exercise and its cessation decrease and increase, respectively, body weight and intra‐abdominal fat, and these changes are proportional to the change in exercise dose.     

Cardiorespiratory Fitness and the Risk of Overweight in Youth: The Healthy Hearts Longitudinal Study of Cardiometabolic Health

The primary objective of this longitudinal study was to determine the association between cardiorespiratory fitness and the risk of overweight status in youth. To accomplish this aim we analyzed data from annual school‐based surveys of cardiorespiratory fitness and anthropometry conducted between 2004 and 2006. The first analysis was performed on a cohort of 902 youth aged 6–15 years followed for 12 months to assess the association between cardiorespiratory fitness levels determined from a graded maximal field test and the risk of becoming overweight. The second analysis was conducted on a cohort of 222 youth followed for 2 years to assess the continuous association between annual changes fitness and weight gain. Children with low cardiorespiratory fitness were characterized by higher waist circumference and disproportionate weight gain over the 12‐month follow‐up period (P < 0.05). Within the entire cohort, the 12‐month risk of overweight classification was 3.5‐fold (95% confidence = 2.0–6.0, P < 0.001) higher in youth with low cardiorespiratory fitness, relative to fit peers. A time series mixed effects regression model revealed that reductions in cardiorespiratory fitness were significantly and independently associated with increasing BMI (r = ?0.18, P < 0.05) in youth. Accordingly, low cardiorespiratory fitness and reductions in fitness over time are significantly associated with weight gain and the risk of overweight in children 6–15 years old. An assessment of cardiorespiratory fitness using a common field test may prove useful for the identification of youth at risk of overweight and serve as a potential target for obesity prevention.     

FTO Genotype and the Weight Loss Benefits of Moderate Intensity Exercise

The fat mass and obesity‐associated (FTO) gene was genotyped for the participants in the Dose‐Response to Exercise in postmenopausal Women (DREW) trial and analyses were performed to determine whether an FTO variant was associated with adiposity and cardiorespiratory fitness (CRF) before and after 6 months of moderate intensity exercise in white women (n = 234). The A/A homozygotes for rs8050136 had a higher BMI (kg/m²) compared to C/C homozygotes at baseline (32.8 (0.6) vs. 31.0 (0.4), respectively; P < 0.05) and at follow‐up (31.9 (0.6) vs. 30.4 (0.5), respectively; P < 0.05). Weight loss occurred after exercise, but there was no significant genotype by exercise interaction over time. Exploratory analyses among women exposed to moderate intensity exercise meeting, or exceeding, the physical activity recommendation found that those homozygous A/A lost significantly more weight than the C allele carriers (?3.3 (0.7) kg vs. ?1.4 (0.4) kg and ?1.5 (0.5) kg, respectively; P < 0.05). CRF, defined as VO_2peak (oxygen consumption), increased after exercise and the magnitude of the increase was similar for each genotype. In conclusion, women genetically predisposed to being obese experienced weight loss and CRF benefits with moderate intensity exercise, with additional weight loss observed when the women met or exceeded the physical activity recommendations.     

Associations of Sedentary Behaviour,Physical Activity,Blood Pressure and Anthropometric Measures with Cardiorespiratory Fitness in Children with Cerebral Palsy

Background

Children with cerebral palsy (CP) have poor cardiorespiratory fitness in comparison to their peers with typical development, which may be due to low levels of physical activity. Poor cardiorespiratory fitness may contribute to increased cardiometabolic risk.

Purpose

The aim of this study was to determine the association between sedentary behaviour, physical activity and cardiorespiratory fitness in children with CP. An objective was to determine the association between cardiorespiratory fitness, anthropometric measures and blood pressure in children with CP.

Methods

This study included 55 ambulatory children with CP [mean (SD) age 11.3 (0.2) yr, range 6-17 yr; Gross Motor Function Classification System (GMFCS) levels I and II]. Anthropometric measures (BMI, waist circumference and waist-height ratio) and blood pressure were taken. Cardiorespiratory fitness was measured using a 10 m shuttle run test. Children were classified as low, middle and high fitness according to level achieved on the test using reference curves. Physical activity was measured by accelerometry over 7 days. In addition to total activity, time in sedentary behaviour and light, moderate, vigorous, and sustained moderate-to-vigorous activity (≥10 min bouts) were calculated.

Results

Multiple regression analyses revealed that vigorous activity (β = 0.339, p<0.01), sustained moderate-to-vigorous activity (β = 0.250, p<0.05) and total activity (β = 0.238, p<0.05) were associated with level achieved on the shuttle run test after adjustment for age, sex and GMFCS level. Children with high fitness spent more time in vigorous activity than children with middle fitness (p<0.05). Shuttle run test level was negatively associated with BMI (r² = -0.451, p<0.01), waist circumference (r² = -0.560, p<0.001), waist-height ratio (r² = -0.560, p<0.001) and systolic blood pressure (r² = -0.306, p<0.05) after adjustment for age, sex and GMFCS level.

Conclusions

Participation in physical activity, particularly at a vigorous intensity, is associated with high cardiorespiratory fitness in children with CP. Low cardiorespiratory fitness is associated with increased cardiometabolic risk.     

Relationships of Age and Weekly Running Distance to BMI and Circumferences in 41, 582 Physically Active Women

Objective: To assess in women whether age‐related increases in adiposity are dependent on exercise, and, contrariwise, whether exercise‐related declines in adiposity are dependent on age. Research Methods and Procedures: Cross‐sectional analyses were conducted of 41, 582 female runners. Results: Age affected the relationships between vigorous exercise and adiposity. The decline in BMI per kilometer per week run was linear in 18 to 23 year olds and became increasingly non‐linear (convex) with age. Waist, hip, and chest circumferences declined significantly with running distance across all age groups, but the declines were significantly greater in older than younger women, particularly among shorter distance runners. The relationships between body circumferences and running distance became increasingly convex in older women. Conversely, vigorous exercise diminished the apparent increase in adiposity with age. The increase in average BMI with age was greatest in women who ran <8 km/wk, intermediate in women who ran 8 to 15 km/wk or 16 to 31 km/wk, and least in those who averaged over 32 km/wk. Before age 45, waist circumference rose for those who ran 0 to 7 km/wk, showed no significant relationship to age for those who ran 8 to 39 km/wk, and declined in those who ran 40 to 55 and 56 km/wk and more. Age related‐increases in hip and chest circumferences before 45 years old were significantly less in women who ran longer weekly distances. Discussion: These cross‐sectional associations are consistent with the hypothesis that exercise may mitigate age‐related increases in adiposity and that age affects exercise‐induced reductions in adiposity (although causality remains to be determined experimentally).     

Cardiorespiratory fitness and sedentary activities are associated with adiposity in adolescents

Objective: To determine whether physical activity, sedentary activities, and/or cardiorespiratory fitness are related to waist circumference in adolescents, as previously reported in adults. Research Methods and Procedures: The study subjects were a representative sample of Spanish adolescents (N = 2859; 1357 boys, 1502 girls; age, 13 to 18.5 years), all of whom were involved in the AVENA (Food and Assessment of the Nutritional Status of Adolescents) study. BMI, waist circumference, pubertal maturation status, and cardiorespiratory fitness were measured in all. Leisure‐time physical activity, sedentary activities, active commuting to school, and socioeconomic status were assessed by self‐reported questionnaires. Results: No relationship was found between leisure‐time physical activity and BMI or waist circumference. In contrast, and in both boys and girls and after adjustment for confounding variables, cardiorespiratory fitness was found to be inversely associated with waist circumference and BMI, independent of sedentary activities or physical activity (p ≤ 0.001). The maximum oxygen consumption explained 13% of the variance in waist circumference in boys and 16% in girls. Sedentary activities were independently and directly related to waist circumference in both boys and girls (p ≤ 0.05) and to BMI in boys (p ≤ 0.05). Sedentary activities explained 10% of the variance in waist circumference in boys and 18% in girls. The BMI‐adjusted waist circumference was inversely correlated with cardiorespiratory fitness in overweight‐obese boys (p ≤ 0.05) and showed a trend toward significance in girls (p ≤ 0.1). Discussion: Both moderate to high levels of cardiorespiratory fitness and sedentary activities, but not physical activity, are associated with lower abdominal adiposity, as measured by waist circumference.     

Adiposity and age explain most of the association between physical activity and fitness in physically active men

Background

To determine if there is an association between physical activity assessed by the short version of the International Physical Activity Questionnaire (IPAQ) and cardiorespiratory and muscular fitness.

Methodology/Principal Findings

One hundred and eighty-two young males (age range: 20–55 years) completed the short form of the IPAQ to assess physical activity. Body composition (dual-energy X-Ray absorptiometry), muscular fitness (static and dynamic muscle force and power, vertical jump height, running speed [30 m sprint], anaerobic capacity [300 m running test]) and cardiorespiratory fitness (estimated VO₂max: 20 m shuttle run test) were also determined in all subjects.Activity-related energy expenditure of moderate and vigorous intensity (EEPA_moderate and EEPA_vigorous, respectively) was inversely associated with indices of adiposity (r = −0.21 to −0.37, P<0.05). Cardiorespiratory fitness (VO₂max) was positively associated with LogEEPA_moderate (r = 0.26, P<0.05) and LogEEPA_vigorous (r = 0.27). However, no association between VO₂max with LogEEPA_moderate, LogEPPA_vigorous and LogEEPA_total was observed after adjusting for the percentage of body fat. Multiple stepwise regression analysis to predict VO₂max from LogEEPA_walking, LogEEPA_moderate, LogEEPA_vigorous, LogEEPA_total, age and percentage of body fat (%fat) showed that the %fat alone explained 62% of the variance in VO₂max and that the age added another 10%, while the other variables did not add predictive value to the model [VO₂max  = 129.6−(25.1× Log %fat) − (34.0× Log age); SEE: 4.3 ml.kg⁻¹. min⁻¹; R² = 0.72 (P<0.05)]. No positive association between muscular fitness-related variables and physical activity was observed, even after adjusting for body fat or body fat and age.

Conclusions/Significance

Adiposity and age are the strongest predictors of VO₂max in healthy men. The energy expended in moderate and vigorous physical activities is inversely associated with adiposity. Muscular fitness does not appear to be associated with physical activity as assessed by the IPAQ.     

Weight loss strategies for obese adults: personalized weight management program vs. standard care

Objective: The objective of this study was to evaluate the effect of a 32‐week personalized Polar weight management program (PWMP) compared with standard care (SC) on body weight, body composition, waist circumference, and cardiorespiratory fitness in overweight or obese adults. Research Methods and Procedures: Overweight or obese (29 ± 2 kg/m²) men and women (n = 74) 38 ± 5 years of age were randomly assigned into either PWMP (men = 20, women = 21) or SC (men = 15, women = 18). Both groups managed their own diet and exercise program after receiving the same standardized nutrition and physical activity advice. PWMP also received a weight management system with literature to enable the design of a personalized diet and exercise weight loss program. Body weight and body composition, waist circumference, and cardiorespiratory fitness were measured at weeks 0, 16, and 32. Results: Eighty percent of participants completed the 32‐week intervention, with a greater proportion of the dropouts being women (PWMP: 2 men vs. 7 women; SC: 2 men vs. 4 women). At 32 weeks, PWMP completers had significantly (p < 0.001) greater losses in body weight [6.2 ± 3.4 vs. 2.6 ± 3.6 (standard deviation) kg], fat mass (5.9 ± 3.4 vs. 2.2 ± 3.6 kg), and waist circumference (4.4 ± 4.5 vs. 1.0 ± 3.6 cm). Weight loss and fat loss were explained by the exercise energy expenditure completed and not by weekly exercise duration. Discussion: More effective weight loss was achieved after treatment with the PWMP compared with SC. The results suggest that the PWMP enables effective weight loss through tools that support self‐monitoring without the requirement of more costly approaches to program supervision.     

Media use and obesity in adolescent females

Objective: In the context of growing public health concern with the obesity rates among children and adolescents, much attention has focused on the role of television as a contributor to the problem. Less attention has been devoted to interactive media (internet surfing and video games), despite the fact that these forms of entertainment are fast gaining in popularity among youth. This study investigated the relative associations of TV viewing and interactive media use with body fat and BMI, controlling for both physical activity participation and cardiovascular fitness. Research Methods and Procedures: Female high‐school adolescents (N = 194) were assessed for cardiovascular fitness (cycle ergometer), percent body fat (DXA), and BMI. Time spent in moderate, vigorous, and sedentary activities was assessed with a 3‐day recall. Results: Multivariate regression analysis showed that only interactive media use was associated with percentage body fat and BMI, and the relationship remained strong even after controlling for physical activity participation and cardiovascular fitness. Discussion: It appears that, among this group of adolescent females, the association between interactive media use and obesity is not explained by a reduction in moderate or vigorous activity commensurate with media use.     

Work‐Related Physical Activity Is Not Associated with Body Mass Index and Obesity

Objective: To analyze the association of work‐related physical activity (WRPA) and leisure‐time physical activity (LTPA) with body mass index (BMI) and obesity in the Spanish adult population aged 20 to 60 years. Research Methods and Procedures: The data were taken from the 1993 Spanish National Health Survey. We analyzed a sample of 12,044 men and women representative of the Spanish population aged 20 to 60 years. BMI and frequency of obesity (BMI ≥ 30 kg/m²) were obtained from self‐reported weight and height. Multiple linear regression and logistic regression models were constructed, adjusting for the main confounding factors. WRPA and LTPA were measured by two questions to classify subjects into four categories of physical activity. Results: Neither mean BMI nor percentage of obesity varied significantly (p > 0.05) by WRPA. Mean BMI was significantly higher (p < 0.01) in those who were inactive in their leisure time (25.90 kg/m² in men and 24.43 kg/m² in women) than in those who reported vigorous activity (24.42 kg/m² and 22.97 kg/m² in men and women, respectively). The odds ration (OR) for obesity decreased with increasing level of LTPA in both men (OR of 0.64 for vigorous activity) and women (OR = 0.68), showing a statistically significant dose‐response relation in both men (for linear trend, p = 0.0021) and women (p = 0.0245). Discussion: These results raise questions about the association between WRPA and obesity and suggest the need to reexamine models of the obesity epidemic that point to automation of the workplace as one of the major explanatory factors.     

Exercise‐Induced Reduction in Obesity and Insulin Resistance in Women: a Randomized Controlled Trial

Objectives : To determine the effects of equivalent diet‐ or exercise‐induced weight loss and exercise without weight loss on subcutaneous fat, visceral fat, and insulin sensitivity in obese women. Research Methods and Procedures : Fifty‐four premenopausal women with abdominal obesity [waist circumference 110.1 ± 5.8 cm (mean ± SD)] (BMI 31.3 ± 2.0 kg/m²) were randomly assigned to one of four groups: diet weight loss (n = 15), exercise weight loss (n = 17), exercise without weight loss (n = 12), and a weight‐stable control group (n = 10). All groups underwent a 14‐week intervention. Results : Body weight decreased by ～6.5% within both weight loss groups and was unchanged in the exercise without weight loss and control groups. In comparison with controls, cardiorespiratory fitness improved within the exercise groups only (p < 0.01). Reduction in total, abdominal, and abdominal subcutaneous fat within the exercise weight loss group was greater (p < 0.001) than within all other groups. The reduction in total and abdominal fat within the diet weight loss and exercise without weight loss groups was greater than within controls (p < 0.001) but not different from each other (p > 0.05). Visceral fat decreased within all treatment groups (p < 0.008), and these changes were not different from each other. In comparison with the control group, insulin sensitivity improved within the exercise weight loss group alone (p < 0.001). Discussion : Daily exercise without caloric restriction was associated with substantial reductions in total fat, abdominal fat, visceral fat, and insulin resistance in women. Exercise without weight loss was also associated with a substantial reduction in total and abdominal obesity.     

Resistance training conserves fat-free mass and resting energy expenditure following weight loss

Objective: To determine what effect diet‐induced ～12 kg weight loss in combination with exercise training has on body composition and resting energy expenditure (REE) in premenopausal African‐American (AA) and European‐American (EA) women. Methods and Procedures: This study was a longitudinal, randomized weight loss clinical intervention, with either aerobic (AT), resistance (RT), or no exercise training (NT). Forty‐eight AA and forty‐six EA premenopausal overweight (BMI between 27 and 30) women underwent weight loss to a BMI <25. Body composition (densitometry), REE (indirect calorimetry), maximal oxygen uptake (VO₂max), and muscular strength (isometric elbow flexion) were evaluated when subjects were in energy balance. Results: AA women lost less fat‐free mass (FFM, P ≤ 0.05) (47.0 ± 4.6 to 46.9 ± 5.0 kg) than EA women (46.4 ± 4.9 to 45.2 ± 4.6 kg). Regardless of race, RT maintained FFM (P ≤ 0.05) following weight loss (46.9 ± 5.2 to 47.2 ± 5.0 kg) whereas AT (45.4 ± 4.2 to 44.4 ± 4.1 kg) and NT (47.9 ± 4.7 to 46.4 ± 5.1 kg) decreased FFM (P ≤ 0.05). Both AT and NT decreased in REE with weight loss but RT did not. Significant time by group interactions (all P ≤ 0.05) for strength indicated that RT maintained strength and AT did not. Discussion: AA women lost less FFM than EA women during equivalent weight losses. However, following weight loss in both AA and EA, RT conserved FFM, REE, and strength fitness when compared to women who AT or did not train.     

The Outcomes of a 12-Week Internet Intervention Aimed at Improving Fitness and Health-Related Quality of Life in Overweight Adolescents: The Young & Active Controlled Trial

Background

Overweight and obesity among adolescents may have consequences, with potentially lasting effects on health and health-related quality of life (HRQoL). Excess weight is also associated with decreases in physical activity and cardiorespiratory fitness. The aim of the current study was to investigate the short-term effects of a 12-week Internet intervention in a primary care setting intended to increase cardiorespiratory fitness and HRQoL among overweight and obese adolescents.

Methods

In this controlled trial, participants (13–15 years) were non-randomly allocated to an intervention- or a control group. The intervention group received 12-weeks access to an online program providing tailored physical activity counseling based on principles from Self-determination Theory and Motivational Interviewing. The control group received standard follow-up by the school nurses. The primary outcome measure of cardiorespiratory fitness was determined using a shuttle run test. The secondary outcomes: HRQoL, leisure time exercise, body image and self-determined motivation for physical activity and exercise, were assessed by self-report measures. Age- and gender-adjusted body mass index (BMI) was calculated based on measurements of height and weight. To compare pre-to post intervention differences within groups, a paired samples t-test was used while crude differences between groups were analyzed with an independent samples t-test.

Results

Of the 120 participants, 108 completed the study, 75 in the intervention group and 33 in the control group. Exposure to the intervention had a small effect on cardiorespiratory fitness (0.14; 95% CI [0.01;0.28]; P = 0.04), and a moderate effect on HRQoL (5.22; 95% CI [0.90; 9.53]; P = 0.02). Moreover, the control group increased significantly in BMI, yielding a moderate preventive effect on BMI (−0.39; 95% CI [−0.74;−0.03]; P = 0.03) for the intervention group.

Conclusion

The results suggest that the Internet intervention with tailored physical activity counseling can have beneficial short-term effect on cardiorespiratory fitness, HRQoL and BMI among adolescents with overweight and obesity.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01700309","term_id":"NCT01700309"}}NCT01700309     

Exercise effect on weight and body fat in men and women

Objectives: The effect of national exercise recommendations on adiposity is unknown and may differ by sex. We examined long‐term effects of aerobic exercise on adiposity in women and men. Research Methods and Procedures: This was a 12‐month randomized, controlled clinical trial testing exercise effect on weight and body composition in men (N = 102) and women (N = 100). Sedentary/unfit persons, 40 to 75 years old, were recruited through physician practices and media. The intervention was facility‐ and home‐based moderate‐to‐vigorous intensity aerobic activity, 60 min/d, 6 days/wk vs. controls (no intervention). Results: Exercisers exercised a mean 370 min/wk (men) and 295 min/wk (women), and seven dropped the intervention. Exercisers lost weight (women, ?1.4 vs. +0.7 kg in controls, p = 0.008; men, ?1.8 vs. ?0.1 kg in controls, p = 0.03), BMI (women, ?0.6 vs. +0.3 kg/m² in controls, p = 0.006; men, ?0.5 kg/m² vs. no change in controls, p = 0.03), waist circumference (women, ?1.4 vs. +2.2 cm in controls, p < 0.001; men, ?3.3 vs. ?0.4 cm in controls, p = 0.003), and total fat mass (women, ?1.9 vs. +0.2 kg in controls, p = 0.001; men, ?3.0 vs. +0.2 kg in controls, p < 0.001). Exercisers with greater increases in pedometer‐measured steps per day had greater decreases in weight, BMI, body fat, and intra‐abdominal fat (all p trend < 0.05 in both men and women). Similar trends were observed for increased minutes per day of exercise and for increases in maximal oxygen consumption. Discussion: These data support the U.S. Department of Agriculture and Institute of Medicine guidelines of 60 min/d of moderate‐to‐vigorous physical activity.     

Fitness Alters the Associations of BMI and Waist Circumference with Total and Abdominal Fat

Objective: We tested the following hypotheses in black and white men and women: 1) for a given BMI or waist circumference (WC), individuals with moderate cardiorespiratory fitness (CRF) have lower amounts of total fat mass and abdominal subcutaneous and visceral fat compared with individuals with low CRF; and 2) exercise training is associated with significant reductions in total adiposity and abdominal fat independent of changes in BMI or WC. Research Methods and Procedures: The sample included 366 sedentary male (111 blacks and 255 whites) and 462 sedentary female (203 blacks and 259 whites) participants in the HERITAGE Family Study. The relationships between BMI and WC with total fat mass (determined by underwater weighing) and abdominal subcutaneous and visceral fat (determined by computed tomography) were compared in subjects with low (lower 50%) and moderate (upper 50%) CRF. The effects of a 20‐week aerobic exercise training program on changes in these adiposity variables were examined in 86% of the subjects. Results: Individuals with moderate CRF had lower levels of total fat mass and abdominal subcutaneous and visceral fat than individuals with low CRF for a given BMI or WC value. The 20‐week aerobic exercise program was associated with significant reductions in total adiposity and abdominal fat, even after controlling for reductions in BMI and WC. With few exceptions, these observations were true for both men and women and blacks and whites. Discussion: These findings suggest that a reduction in total adiposity and abdominal fat may be a means by which CRF attenuates the health risk attributable to obesity as determined by BMI and WC.     

Categorization of low cardiorespiratory fitness using obesity indices in non-smoking Singaporean women

Objective: To revisit cut‐off values of BMI, waist circumference (WC), and waist‐to‐stature ratio (WSR) based on their association with cardiorespiratory fitness (CRF). The derived cut‐off points were compared with current values (BMI, 25.0 kg/m²; WC, 80 cm) as recommended by the World Health Organization. Research Methods and Procedures: Anthropometric indices were measured in a cross sectional study of 358 Singaporean female employees of a large tertiary hospital (63% Singaporean Chinese, 28% Malays, and 9% Indians). CRF was determined by the 1‐mile walk test. Receiver operating characteristic curves were constructed to determine cut‐off points. Results: The cut‐off points for BMI, WC, and WSR were 23.6 kg/m², 75.3 cm, and 0.48, respectively. The areas under the curve of BMI, WC, and WSR were 0.68, 0.74, and 0.74, respectively. For a given BMI, women with low CRF had higher WSR compared with women with high CRF. Discussion: These findings provide convergent evidence that the cut‐off points for Singaporean women were lower than the World Health Organization's criteria but were in good agreement with those reported for Asians.     

A 12-Week Exercise Program for Pregnant Women with Obesity to Improve Physical Activity Levels: An Open Randomised Preliminary Study

Objective

To evaluate whether a 12-week supervised exercise program promotes an active lifestyle throughout pregnancy in pregnant women with obesity.

Methods

In this preliminary randomised trial, pregnant women (body mass index ≥ 30 kg/m²) were allocated to either standard care or supervised training, from 15 to 27 weeks of gestation. Physical activity was measured by accelerometry at 14, 28 and 36 weeks, while fitness (oxygen consumption (VO₂) at the anaerobic threshold), nutrition (caloric intake and macronutrients percentage) and anthropometry were assessed at 14 and 28 weeks of gestation. Analyses were performed using repeated measures ANOVA.

Results

A total of fifty (50) women were randomised, 25 in each group. There was no time-group interaction for time spent at moderate and vigorous activity (p_interaction = 0.064), but the exercise group’s levels were higher than controls’ at all times (p_{group effect} = 0.014). A significant time-group interaction was found for daily physical activity (p = 0.023); similar at baseline ((22.0 ± 6.7 vs 21.8 ± 7.3) x 10⁴ counts/day) the exercise group had higher levels than the control group following the intervention ((22.8 ± 8.3 vs 19.2 ± 4.5) x 10⁴ counts/day, p = 0.020) and at 36 weeks of gestation ((19.2 ± 1.5 vs 14.9 ± 1.5) x 10⁴ counts/day, p = 0.034). Exercisers also gained less weight than controls during the intervention period despite similar nutritional intakes (difference in weight change = -0.1 kg/week, 95% CI -0.2; -0.02, p = 0.016) and improved cardiorespiratory fitness (difference in fitness change = 8.1%, 95% CI 0.7; 9.5, p = 0.041).

Conclusions

Compared with standard care, a supervised exercise program allows pregnant women with obesity to maintain fitness, limit weight gain and attenuate the decrease in physical activity levels observed in late pregnancy.

Trial Registration

ClinicalTrials.gov NCT01610323     

Weight cycling and 6-year weight change in healthy adults: The Aerobics Center Longitudinal Study

Objective: To determine the longitudinal relationship between a reported history of weight cycling and the trajectory of weight in a group of normal‐weight to obese women and men. Research Methods and Procedures: This was a clinic‐based cohort study conducted over 6 years. Subjects were healthy women (n = 141) and men (n = 797) age 20 to 78 years who completed at least four comprehensive medical exams at the Cooper Clinic (Dallas, TX) between 1987 and 2003. Weight loss history was reported, and body weight was measured at all examinations. Weight cycling status was derived from weight loss history and defined as ≥five episodes of weight loss of ≥2.3 kg/episode. Using linear mixed effects models, weight at each examination was regressed on weight cycling status separately for women and men while controlling for selected covariables. Results: Baseline BMI was 23 and 21 kg/m² among cycling and non‐cycling women and was 27 and 25 kg/m² among cycling and non‐cycling men, respectively. We observed a non‐significant difference (p = 0.09) in women by cycling status (average weight gain = 0.5 and 0.2 kg/yr among cyclers and non‐cyclers, respectively) and no difference in weight gain over time among men by cycling status (average weight gain = 0.2 kg/yr among both groups, p = 0.99). Higher baseline cardiorespiratory fitness level and increased fitness over the follow‐up were associated with attenuated weight gain in both women and men. Discussion: In healthy, middle‐aged individuals, a history of weight cycling does not seem to increase the risk of long‐term weight gain in men; however, this relation needs to be studied further in women.