Abdominal obesity and metabolic syndrome: exercise as medicine?

Background: Metabolic syndrome is defined as a cluster of at least three out of five clinical risk factors: abdominal (visceral) obesity, hypertension, elevated serum triglycerides, low serum high-density lipoprotein (HDL) and insulin resistance. It is estimated to affect over 20% of the global adult population. Abdominal (visceral) obesity is thought to be the predominant risk factor for metabolic syndrome and as predictions estimate that 50% of adults will be classified as obese by 2030 it is likely that metabolic syndrome will be a significant problem for health services and a drain on health economies.Evidence shows that regular and consistent exercise reduces abdominal obesity and results in favourable changes in body composition. It has therefore been suggested that exercise is a medicine in its own right and should be prescribed as such. Purpose of this review: This review provides a summary of the current evidence on the pathophysiology of dysfunctional adipose tissue (adiposopathy). It describes the relationship of adiposopathy to metabolic syndrome and how exercise may mediate these processes, and evaluates current evidence on the clinical efficacy of exercise in the management of abdominal obesity. The review also discusses the type and dose of exercise needed for optimal improvements in health status in relation to the available evidence and considers the difficulty in achieving adherence to exercise programmes. Conclusion: There is moderate evidence supporting the use of programmes of exercise to reverse metabolic syndrome although at present the optimal dose and type of exercise is unknown. The main challenge for health care professionals is how to motivate individuals to participate and adherence to programmes of exercise used prophylactically and as a treatment for metabolic syndrome

Abdominal obesity and low physical activity are associated with insulin resistance in overweight adolescents: a cross-sectional study

ABSTRACT: Background: Previous studies have assessed the metabolic changes and lifestyles associated with overweight adolescents. However, these associations are unclear amongst overweight adolescents who have already developed insulin resistance. This study assessed the associations between insulin resistance and anthropometric, metabolic, inflammatory, food consumption, and physical activity variables amongst overweight adolescents. Methods: This cross-sectional study divided adolescents (n = 120) between 10 and 18 years old into 3 groups: an overweight group with insulin resistance (O + IR), an overweight group without insulin resistance (O-IR), and a normal-weight control group (NW). Adolescents were matched across groups based on age, sex, pubertal maturation, and socioeconomic strata. Anthropometric, biochemical, physical activity, and food consumption variables were assessed. Insulin resistance was assessed using homeostatic model assessment (HOMA Calculator Version 2.2.2 from ©Diabetes Trials Unit, University of Oxford), and overweight status was assessed using body mass index according to World Health Organization (2007) references. A chi-square test was used to compare categorical variables. ANOVAs or Kruskal-Wallis tests were used for continuous variables. Multiple linear regression models were used to calculate the probability of the occurrence of insulin resistance based on the independent variables. Results: The risk of insulin resistance amongst overweight adolescents increases significantly when they reach a waist circumference > p95 (OR = 1.9, CIs = 1.3-2.7, p = 0.013) and watch 3 or more hours/day of television (OR = 1.7, CIs = 0.98-2.8, p = 0.033). Overweight status and insulin resistance were associated with higher levels of inflammation (hsCRP ≥1 mg/L) and cardiovascular risk according to arterial indices. With each cm increase in waist circumference, the HOMA index increased by 0.082; with each metabolic equivalent (MET) unit increase in physical activity, the HOMA index decreased by 0.026. Conclusions: Sedentary behaviour and a waist circumference > p90 amongst overweight adolescents were associated with insulin resistance, lipid profile alterations, and higher inflammatory states. A screening that includes body mass index, in waist circumference, and physical activity evaluations of adolescents might enable the early detection of these alterations

THE AGREEMENT OF BODY FAT PERCENTAGE ESTIMATES FROM ULTRASOUND, SKINFOLD, AND AN UNDERWATER WEIGHING CRITERION

Katherine Sullivan, Casey J. Metoyer, Michael R. Esco, Michael V. Fedewa. University of Alabama, Tuscaloosa, AL. BACKGROUND: Accurate measures of body composition are clinically important, as higher adiposity is associated with various unfavorable health outcomes. Ultrasound has been proposed as a viable alternative to skinfold (SKF) thickness for the estimation of body fat (%Fat) as it may overcome reliability concerns often associated with SKF measurement. However, ultrasound has not been extensively examined in generally healthy, young adults. Therefore, the purpose of this study was to examine the agreement between %Fat from ultrasound (%FatUS), skinfold thickness (%FatSKF), and an underwater weighing (%FatUWW) criterion. METHODS: A convenience sample of 46 young adults were included in our analysis (28.3% female, 82.6% Caucasian, 22.8±4.1 yrs., 24.3±3.5 kg/m2). Ultrasound and SKF measurements were taken on the same seven standardized sites on the right side of the body by the same evaluator. For each participant, two SKF and ultrasound measures were taken at each site. For each measurement site, the two SKF and ultrasound measures were averaged. The averaged SKF site measures were then summed. The averaged ultrasound site measures were converted to millimeters, doubled, and then summed. The sum of SKF and ultrasound measures were used separately to calculate body density via the gender specific Jackson and Pollock equations. Body density via underwater weighing (UWW) served as the criterion measure. Subsequently, %FatUS, %FatSKF, and %FatUWW were calculated using the Siri equation (%Fat = [495/body density] - 450). A repeated measures ANOVA examined potential differences between %FatUS, %FatSKF, and %FatUWW. Data are presented as mean ± standard deviation, with p\u3c0.05 used to determine statistical significance. RESULTS: A small, non-significant mean difference was observed between %FatUS (19.3±9.1 %Fat) and %FatUWW (18.1±6.8 %Fat) (ES=0.18, p = 0.11). A small, but statistically significant, mean difference was observed between %FatSKF (19.3±7.1 %Fat) and %FatUWW (18.1±6.8 %Fat) (ES=0.18, p = 0.05). Both, %FatUS (r =.818, SEE=3.9 %Fat, p\u3c.001) and %FatSKF (r =.808, SEE=4.0 %Fat, p\u3c.001) yielded similar agreement with %FatUWW. CONCLUSIONS: Ultrasound and SKF were comparable to UWW when measured using Jackson and Pollock’s 7-site body density equations. However, the time burden to participants and added financial cost may not justify the utility of ultrasound within generally healthy, young adults

ABSOLUTE PEAK OXYGEN CONSUMPTION IS INDEPENDENTLY CORRELATED WITH FAT-FREE MASS IN YOUTH SOCCER PLAYERS

Casey J. Metoyer, Oleg Sinelnikov, Michael V. Fedewa, Michael R. Esco, FACSM. The University of Alabama, Tuscaloosa, AL. BACKGROUND: It has been suggested that the relationship between body mass (BM) and peak oxygen consumption (VO2peak) is explained by fat-free mass (FFM) and not fat mass (FM). However, most of the research has occurred in children and adults with obesity, and hence, little is known about these relationships in youth athletes. Therefore, the purpose of the study was to determine the extent of variation in absolute VO2peak that can be independently explained by BM, FM, and FFM in youth soccer players. METHODS: A sample of 20 young male soccer players (age = 13.7 ± 0.8 years, height = 167.0 ± 7.9 cm, weight = 56.2 ± 8.4 kg) participated in this study. Absolute VO2peak was determined from a maximal graded exercise test on a treadmill. Dual-energy x-ray absorptiometry was used to measure FM and FFM. Pearson correlation procedures were used to determine the relationships between absolute VO2peak and the body composition metrics. Stepwise regression was used to determine which body composition metric (BM, FM, or FFM) explained the greatest variation in absolute VO2peak. RESULTS: The average absolute VO2peak, FM, and FFM was 3.1 ± 0.6 L/min, 11.1 ± 2.9 kg, and 46.0 ± 6.9 kg, respectively. Significant correlations were found between VO2peak and BM (r = 0.88, p \u3c 0.001), FM (r = 0.46, p = 0.02), and FFM (r = 0.90, p \u3c 0.001). Stepwise regression showed that only FFM significantly explained the variance in absolute VO2peak (R2 = 0.81, p \u3c 0.001). CONCLUSIONS: The results of this study suggest that FFM explains the relationship between BM and absolute VO2peak in youth soccer players. FM does not display an independent relationship with VO2peak. Therefore, fatness and absolute VO2peak appear to be independent qualities in male youth soccer players. Further research is needed to verify these findings and clarify the relationship between body composition and oxygen consumption in youth athletes

ESTIMATION OF TOTAL BODY WATER USING SINGLE FREQUENCY BIOIMPEDANCE ANALYSIS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Zackary S. Cicone1, Michael V. Fedewa2, Clifton J. Holmes3, Michael R. Esco, FACSM2, Hayley V. MacDonald2. 1Shenandoah University, Winchester, VA. 2The University of Alabama, Tuscaloosa, AL. 3Washington University in St. Louis, St. Louis, MO. BACKGROUND: Single frequency bioimpedance analysis (SFBIA) is a simple alternative to isotope dilution techniques for assessing total body water (TBW). How characteristics related to the sample (e.g., age, health status) and SFBIA methodology (e.g., criterion technique, device, frequency, index) influence SFBIA accuracy has yet to be comprehensively examined. The aims of this systematic review and meta-analysis were to 1) quantify the accuracy of SFBIA for predicting TBW and 2) determine the potential impact of study-level effect modifiers. METHODS: Five electronic databases were searched for studies that compared isotope dilution TBW values to SFBIA. Standardized mean difference (SMD) effect sizes were calculated using the Gibbons method for each comparison and an overall estimate was generated using a three-level random-effects model. Within- and between-study level variance was evaluated using one-sided log-likelihood-ratio tests. When appropriate, subgroup analyses were performed to identify potential study-level moderators. RESULTS: Aggregate-level data from 51 studies (255 individual effects) were included in the final analysis. Study samples included predominantly healthy participants with large ranges in mean age (0 to 82 y) and body mass index (14.1 to 50.2 kg/m2). The overall SMD indicated a negligible difference between SFBIA and criterion dilution methods (SMD=-0.04, p=0.67), but lacked homogeneity at both the within- (σ2=0.45) and between-study (σ2=0.26) levels (all p\u3c0.001). Moderator analysis revealed that the interaction between frequency and index (p\u3c0.01) influenced the observed error between SFBIA and criterion methods. Resistance index (Ht2/R) produced less error than impedance index (Ht2/Z) across all frequencies (all p\u3e0.10), with Ht2/R at 50 kHz producing the most accurate estimate of TBW (β=0.06, p\u3e0.05). Additionally, there was a small yet significant effect for sample sex (% women, β=-0.003, p\u3c0.05), suggesting that SFBIA may underestimate TBW in samples that are predominantly women. No main effects were observed for other study-level factors (e.g., sample characteristics or BIA methodology). CONCLUSION: Overall, Ht2/R produced less error in TBW estimation than Ht2/Z, with Ht2/R at 50 kHz providing the smallest mean difference in TBW when compared to isotope dilution. These results suggest that SFBIA may provide acceptable estimates of TBW across a range of diverse samples

RELIABILITY OF BODY COMPOSITION MEASURED USING A SMARTPHONE APPLICATION AND DIFFERENT CAMERA RESOLUTIONS

Mary E. Lovelady, Casey J. Metoyer, Katherine Sullivan, Jacob Broeckel, Michael R. Esco, FACSM, Michael V. Fedewa. University Of Alabama, Tuscaloosa, AL. BACKGROUND: Many traditional laboratory methods of measuring body fat percentage (%Fat) are inaccessible to healthcare professionals due to the cost, complexity, time, and portability. Recently, a new smartphone application was developed that allows for an accurate estimate of %Fat by analyzing a single 2-dimensional digital image. Although the validity of the application has been previously examined, the reliability across different camera resolutions has not been thoroughly tested. PURPOSE: The aim of this study was to evaluate the reliability of %Fat estimates from digital images captured using devices with different megapixel cameras. METHODS: A convenience sample of adult participants was recruited for the study (n=12, 83.33% female, 83.33% Caucasian, 31.25±10.49 yrs., 69.44±11.77 kg/m2). Age, gender, and race/ethnicity were assessed via self-report. Height was measured to the nearest 0.1 cm using a stadiometer (SECA 213, Seca Ltd., Hamburg, Germany). Weight was measured to the nearest 0.1 kg using a calibrated digital scale (Tanita BWB-800, Tanita Corporation, Tokyo, Japan). A full-body digital image was taken from the posterior view, with participants standing in front of a white background, using a 12-megapixel iPhone 12 (Apple Inc., Cupertino, CA) (%Fat12mp) and an 8-megapixel iPad Air 2 (Apple Inc., Cupertino, CA) (%Fat8mp). %Fat was derived using an automated smartphone application and a proprietary algorithm (made Health and Fitness, LLC, Birmingham, AL). A paired samples t-test was used to examine potential mean differences between %Fat12mp and %Fat8mp. The reliability was also measured using Pearson’s r, and described as weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, or 0.9 respectively). Data are presented as mean±standard deviation, with an alpha level set to p\u3c0.05. RESULTS: No significant mean differences in %Fat were observed between %Fat12mp and %Fat8mp (26.92±4.96 %Fat and 27.16±3.08 %Fat, respectively; p=0.37). Near-perfect correlations were observed between %Fat12mp and %Fat8mp (r=0.99, p\u3c0.001). DISCUSSION: Based on the results of this study, the smartphone application provides a reliable estimate of %Fat across devices with different megapixel cameras. Future studies should explore other conditions, including different lighting, different color backgrounds, and other devices, as well as within a larger more diverse sample

THE TEST-RETEST RELIABILITY OF BODY COMPOSITION MEASURED USING DIGITAL IMAGES FROM A SMARTPHONE APPLICATION

Madeline L. Schwing, Casey J. Metoyer, Katherine Sullivan, Mary E. Lovelady, Michael R. Esco, FACSM, Michael V. Fedewa, FACSM. University of Alabama, Tuscaloosa, AL, AL. BACKGROUND: The ability to measure and track changes in muscle and fat is important for practitioners in the Allied Health and Sports Performance fields. An automated image analysis program was recently developed to measure muscle and fat from a single digital image using a smartphone application. However, the reliability of the application has yet to be assessed. PURPOSE: The purpose of this study was to evaluate the test-retest reliability of %Fat estimates from a single digital image when measured on two consecutive days. METHODS: A convenience sample of participants were included in the study (n=12, 83.33% female, 83.33% Caucasian 31.25±10.49 yrs, 24.82 kg/m2). Data collection occurred on two consecutive days with no more than 36 hours between visits. On Day 1, age, gender, and race were assessed via self-report. A full-body image from the posterior view was taken using an iPad Air 2 (Apple Inc., Cupertino, CA) against a white photography backdrop. A light meter (MT-912, Shenzhen Flus Technology Co., Ltd., Shenzhen, China) was used to measure brightness in Lux and ensure that testing conditions were consistent across both days. Participants returned on Day 2 and performed a second %Fat measurement under similar lighting and backdrop conditions. Images were analyzed using an automated smartphone application (made Health and Fitness LLC, Birmingham, AL. version 1.1.3), which provided estimates of %Fat using a proprietary algorithm. A paired samples t-test was used to assess potential mean differences in %Fat across the two trials. The test-retest reliability across the trials was measured using Pearson’s r, and described as weak, moderate, strong, or near-perfect (r=0.2, 0.5, 0.8, or 0.9, respectively). Data are presented as mean± standard deviation, with statistical significance set at p\u3c0.05. RESULTS: No significant mean differences were observed between measurements obtained on Day 1 (27.16±5.08 %Fat) and Day 2 (27.04±5.49 %Fat) (p=0.65). In addition, a near-perfect correlation was observed between the trials (r=0.99, p\u3c0.001). CONCLUSION: Given the negligible difference between measures and the near-perfect correlation, an inexpensive and portable technique to measure %Fat in field settings may be a valuable alternative when traditional assessment techniques are not available. Future research should examine the reliability across multiple camera types, image resolutions, lighting conditions, and color backgrounds

ASSOCIATION BETWEEN HEALTH-RELATED COMPONENTS AND BODY DISSATISFACTION IN WOMEN

Katherine Sullivan, Jacob Broeckel, Casey J. Metoyer, Andrew D. Fields, Madelyn K. Simmang, Michael R. Esco, FACSM, Michael V. Fedewa. University of Alabama, Tuscaloosa, AL. BACKGROUND: Body dissatisfaction refers to a negative perception or evaluation of one’s body or physical appearance. Higher body dissatisfaction negatively impacts self-esteem, perceived quality of life, and can increase the risk of disordered eating, substance abuse, anxiety, and depression. PURPOSE: To examine the association between body dissatisfaction and health-related components among women. METHODS: A convenience sample of 29 female adults were included in our analysis (90% Caucasian, 24.8±9.2 yrs., 24.9±3.6 kg/m2). Body mass and height were measured and used to calculate body mass index (BMI). Body dissatisfaction scores (BDS) were calculated using the body dissatisfaction subscale of the eating disorder inventory II (EDI-BD). Where applicable, EDI-BD items were reverse scored such that, higher BDS scores indicate greater body dissatisfaction. Health-related components included waist and hip circumference (cm), number of push-ups completed until exhaustion, average dominant and non-dominant hand-grip strength (kg), participant’s perceived functional ability to walk, jog, or run a one-mile and three-mile distance, BMI (kg/m2), physical activity (MET-minutes/week) derived from the short form International Physical Activity Questionnaire, and relative adiposity (%Fat) derived from Dual X-ray Absorptiometry. Bivariate correlations were used to examine the direction and strength of the association between BDS and health-related components. The strength of each r value was considered weak (r=0.2), moderate (r=0.5), or strong (r=0.8). Data are presented as mean±standard deviation, with p\u3c0.05 used to determine statistical significance. RESULTS: No statistically significant correlations (p\u3e.05 for all) were observed between BDS and waist or hip circumference (r=.144, r=.282, respectively), push-ups (r=-.215), dominant or non-dominant hand-grip strength (r=-.121, r=-.086, respectively), perceived ability to complete one-mile or three-miles (r=-.289, r=-.258), BMI (r=.240), or physical activity (r=.094). Significant, moderate correlations were observed between BDS and %Fat (r=.426, p=.021). CONCLUSIONS: Our results indicate a moderate, linear relationship between %Fat and body dissatisfaction. Given the relatively homogenous age, race, and BMI characteristics of the current study, the association between body dissatisfaction and health-related components should be further examined within a larger and more diverse sample