Quantile Differences in the Age-Related Decline in Cardiorespiratory Fitness Between Sexes in Adults Without Type 2 Diabetes Mellitus in the United States.

Objective: To comprehensively assess the extent to which the decline in cardiorespiratory fitness (CRF) with age differs between sexes. Participants and Methods: This study used data from the Aerobics Center Longitudinal Study, conducted between September 1974 and August 2006, consisting primarily of White adults from middle-to-upper socioeconomic strata restricted to adults without type 2 diabetes mellitus (33,742 men and 9,415 women). Quantile regression models were used to estimate the differences in age-associated changes in CRF between the sexes, estimated using a maximal treadmill test. Results: For adults aged up to 45 years, significant differences in slopes relating to age and CRF between men and women were observed for all adjusted percentiles of CRF other than the 90th percentile; women reported significantly greater declines in CRF per year. For those aged 45-60 years and those older than 60 years, no significant differences in age-related declines in CRF were observed between the sexes. Conclusion: This study found that compared with men, the onset of decline in CRF was found to occur earlier and at lower CRF percentiles in women. This is of particular concern, given that compared with men, women already tend to have lower CRF levels. These findings suggest that maintaining the levels of physical activity sufficient to maintain moderate-to-high levels of fitness is particularly important for women earlier during adulthood.

Fit to Play? Health-Related Fitness Levels of Youth Athletes: A Pilot Study.

ABSTRACT: Pfeifer, CE, Sacko, RS, Ortaglia, A, Monsma, EV, Beattie, PF, Goins, J, and Stodden, DF. Fit to play? Health-related fitness levels of youth athletes: A pilot study. J Strength Cond Res 36(1): 245-251, 2022-A recent National Strength and Conditioning Association position statement suggests that many youth are not prepared for the physical demands of sport. The purpose of this study was to compare health-related fitness (HRF) of youth athletes with normative findings from the general population. We recruited 136 athletes (63 male and 73 female athletes) aged 11-19 (16.01 ± 1.35) years and collected HRF (body composition, cardiorespiratory endurance, musculoskeletal strength and endurance). Results were categorized based on FITNESSGRAM® standards and compared with Canadian youth general population normative data. Most male athletes were classified as "needs improvement" for cardiorespiratory and muscular endurance, and body mass index (BMI). Conversely, most female athletes were at or above the "healthy fitness zone" for all measures. Male athletes at both age groups (11-14, 15-19; p < 0.001) and female athletes aged 11-14 (p < 0.05) demonstrated lower cardiorespiratory endurance compared with Canadian general population. Female athletes (both age groups) demonstrated greater muscular strength, and male athletes (age, 15-19 years) demonstrated lower BMI than the Canadian general population. The results are concerning as male athletes demonstrated poorer HRF compared with the general population. Although most female athletes were within healthy ranges, a portion of them were still at risk. Considering the demands sport places on the body, evaluating HRF is paramount for performance and injury prevention but more importantly for overall health. Youth sport and strength coaches should evaluate and aim to enhance HRF, as participation in sport does not guarantee adequate HRF. Promoting long-term athletic development and life-long health should be a priority in youth.

Associations between Fasting Duration, Timing of First and Last Meal, and Cardiometabolic Endpoints in the National Health and Nutrition Examination Survey.

BACKGROUND: Research indicates potential cardiometabolic benefits of energy consumption earlier in the day. This study examined the association between fasting duration, timing of first and last meals, and cardiometabolic endpoints using data from the National Health and Nutrition Examination Survey (NHANES). METHODS: Cross-sectional data from NHANES (2005-2016) were utilized. Diet was obtained from one to two 24-h dietary recalls to characterize nighttime fasting duration and timing of first and last meal. Blood samples were obtained for characterization of C-reactive protein (CRP); glycosylated hemoglobin (HbA1c %); insulin; glucose; and high-density lipoprotein (HDL), low-density lipoprotein (LDL), and total cholesterol. Survey design procedures for adjusted linear and logistic regression were performed. RESULTS: Every one-hour increase in nighttime fasting duration was associated with a significantly higher insulin and CRP, and lower HDL. Every one-hour increase in timing of the last meal of the day was statistically significantly associated with higher HbA1c and lower LDL. Every one-hour increase in first mealtime was associated with higher CRP (ß = 0.044, p = 0.0106), insulin (ß = 0.429, p < 0.01), and glucose (ß = 0.662, p < 0.01), and lower HDL (ß = -0.377, p < 0.01). CONCLUSION: In this large public health dataset, evidence for the beneficial effect of starting energy consumption earlier in the day on cardiometabolic endpoints was observed.

Differential Age-Related Declines in Cardiorespiratory Fitness Between People With and Without Type 2 Diabetes Mellitus.

OBJECTIVE: To assess the extent to which the established age-related decline in cardiorespiratory fitness (CRF) is augmented in adult men with type 2 diabetes mellitus (T2DM). PARTICIPANTS AND METHODS: This study used data from the Aerobics Center Longitudinal Study, conducted between September 18, 1974, and August 3, 2006, in primarily non-Hispanic white, middle-to-upper class adults. The analyses were restricted to adult men with complete data on age, CRF, and T2DM (35,307 participants). Quantile regression models were used to estimate age-related differences in CRF, estimated using a maximal treadmill test, between persons with and without T2DM. Smoking status and birth cohort served as covariates. RESULTS: Age-related declines in CRF were observed in men with and without T2DM. For men younger than 60 years, at low-mid percentiles of the CRF distribution the magnitude of the age-related decline in CRF was significantly higher (P-values=.00, .02) in men with T2DM than in those without T2DM. At upper percentiles, the decline with age between the 2 groups was virtually identical. Significant declines in CRF in men 45 years or younger were observed only at high levels of CRF for those without T2DM and at low levels of CRF for those with T2DM (P-values .00, .04). CONCLUSION: This study reported that men younger than 60 years with T2DM at the low-mid CRF percentiles experience an accelerated age-related decline in CRF. Men younger than 60 years with T2DM exhibiting high levels of CRF experienced a decline in CRF comparable to men without T2DM. This study highlights the importance of incorporating sufficient levels of exercise or activity to maintain high CRF in men with T2DM.

Differential relationships between waist circumference and cardiorespiratory fitness among people with and without type 2 diabetes.

Adults with type 2 diabetes mellitus tend to exhibit an increased level of central adiposity, augmenting their risk of further non-communicable diseases (NCDs). Importantly, consistent evidence demonstrates a significant, negative association between cardiorespiratory fitness (CRF) and waist circumference (WC). However, no previous studies have investigated differences in these CRF-related reductions in WC between adults with and without diabetes. This study used data from the Aerobic Center for Longitudinal Studies, conducted between 1970 and 2006 among predominately Non-Hispanic White, middle-to-upper class adults in Texas. Quantile regression models were used to estimate CRF-related differences in WC between persons with and without diabetes. Age, height, smoking status and birth cohort served as covariates. The analytic sample included 45901 adults. Significantly larger reductions in WC were observed among adults with diabetes as compared to without diabetes across all WC percentiles. Among males, high CRF levels were associated with significant reductions, as compared to their low-fit counterparts, in WC as large as 21.9 cm for adults without diabetes and as large as 27 cm for adults with diabetes. Among females, high CRF levels were associated with significant reductions, as compared to their low-fit counterparts, in WC as large as 22.3 and 30.0 cm for adults without and with diabetes, respectively. This study demonstrated that higher CRF is associated with significant reductions in WC, with greater magnitudes found among adults with diabetes, especially among the most centrally obese, highlighting the necessity of exercise prescription in this clinical population potentially leading to lower risks of future NCDs.

FUNCTIONAL MOVEMENT SCREEN™ in YOUTH SPORT PARTICIPANTS: EVALUATING the PROFICIENCY BARRIER for INJURY.

BACKGROUND & PURPOSE: The number of youth participating in sport increases yearly; however, the evaluation of youths' movement ability and preparedness for sport remains inadequate or neglected. The Functional Movement Screen (FMS™) is an assessment of an individual's movement quality that has been utilized to evaluate risk of injury in collegiate and professional sport; however, there is minimal support regarding the predictive value of the screen in youth sport. The purpose of this study was to evaluate the mean and distribution of FMS™ performance in sport participants age 11-18, and to evaluate the existence of a composite FMS™ score proficiency barrier to predict injury risk. STUDY DESIGN: Prospective cohort study. METHODS: One hundred, thirty-six participants (63 male, 73 female) age 11 to 18 years (16.01 + 1.35) were recruited from local schools and sport organizations. The FMS™ was administered prior to each participant's competitive season and scored by researchers who demonstrated reliability in assessments derived from the screen (κw = 0.70 to 1). Injury data were collected by the participants' Athletic Trainer over one season. An injury was defined as any physical insult or harm resulting from sports participation that required an evaluation from a health professional with time modified or time lost from sport participation. RESULTS: Females scored significantly higher than males for mean FMS™ composite score (t = 14.40; m = 12.62; p < 0.001), and on individual measures including: the hurdle step (t = 1.91; m = 1.65; p < 0.001), shoulder mobility (t = 2.68; m = 2.02; p < 0.001), active straight leg raise (t = 2.32; m = 1.87; p < 0.001), and the rotary stability components (t = 1.91; m = 1.65; p < 0.05). Two FMS™ composite scores (score < 14 and <15) significantly increased the odds of injury (OR = 2.955). When adjusting for sport, there was no score relating to increased odds of injury. CONCLUSION: Dysfunctional movement as identified by the FMS™ may be related to increased odds of injury during the competitive season in youth athletes. Consideration of an individual's movement within the context of their sport is necessary, as each sport and individual have unique characteristics. Addressing movement dysfunction may aid in injury reduction and potentially improve sport performance. LEVEL OF EVIDENCE: 1b.

The Role of Energy Intake on Fitness-Adjusted Racial/Ethnic Differences in Central Adiposity Using Quantile Regression.

BACKGROUND: Energy intake (EI) is suggested to be associated with adiposity and may explain previously observed fitness-adjusted racial disparities in waist circumference (WC). OBJECTIVE: The purpose of this study was to comprehensively evaluate the role of EI on the fitness-adjusted racial/ethnic disparities in WC in a nationally representative sample of females using quantile regression. METHODS: Our sample consisted of 3874 female participants (aged 12 to 49 years) from the 1999-2004 National Health and Nutrition Examination Survey. The role of EI was assessed in separate analyses via estimation using a 24-hour dietary recall (DR) and the Institute of Medicine total daily energy expenditure equations. Age-stratified quantile regression models were used to estimate the differences in WC between minority groups and non-Hispanic (NH) white, adjusting for EI, CRF, age, and height. RESULTS: Results from the quantile regression analyses adjusting for EI via DR showed significant differences in WC between NH black and NH white at the 25th-90th WC percentiles (5.9-11.1 cm) for females 20-49 and at the 90th WC percentile (10.1 cm) for females 16-19. For females 12-15, no significant differences were observed between NH black and NH white. Analyses adjusting for EI via IOM showed significant differences in WC between NH black and NH white only for females aged 20-49 years, at the 50th and 75th percentile (1.7-3.6 cm). Compared to NH White, Mexican American females, in all age groups, tended to have significantly greater WC. CONCLUSIONS: These results highlight the importance of rigor in energy intake assessments, suggesting that EI, if adequately assessed, may explain a substantial part of the racial/ethnic differences in WC between NH black and NH white females. Additionally, the observed persistence of estimated differences in WC with advancing age suggests other factors (e.g., hormones) may play a role.

Design, Development and Construct Validation of the Children's Dietary Inflammatory Index.

OBJECTIVE: To design and validate a literature-derived, population-based Children's Dietary Inflammatory Index (C-DII)TM. DESIGN: The C-DII was developed based on a review of literature through 2010. Dietary data obtained from children in 16 different countries were used to create a reference database for computing C-DII scores based on consumption of macronutrients, vitamins, minerals, and whole foods. Construct validation was performed using quantile regression to assess the association between C-reactive protein (CRP) concentrations and C-DII scores. DATA SOURCES: All data used for construct validation were obtained from children between six and 14 years of age (n = 3300) who participated in the U.S. National Health and Nutrition Examination Survey (NHANES) (2005⁻2010). RESULTS: The C-DII was successfully validated with blood CRP concentrations in this heterogeneous sample of 3300 children from NHANES (52% male; 29% African American, 25% Mexican American; mean age 11 years). The final model was adjusted for sex, age, race, asthma, body mass index (BMI), and infections. Children in level 3 (i.e., quartiles 3 and 4 combined) of the C-DII (i.e., children with the most pro-inflammatory diets) had a CRP value 0.097 mg/dL higher than that in level 1 (i.e., quartile 1) for CRP values at the 75th percentile of CRP using quantile regression (p < 0.05). CONCLUSION: The C-DII predicted blood CRP concentrations among children 6⁻14 years in the NHANES. Further construct validation with CRP and other inflammatory markers is required to deepen understanding of the relationship between the C-DII and markers of inflammation in children.

Differential association of cardiorespiratory fitness and central adiposity among US adolescents and adults: A quantile regression approach.

Previous studies assessing the association between cardiorespiratory fitness (CRF) and waist circumference (WC) have often restricted their evaluation to the association of CRF on average WC. Consequently, the assessment of important variations in the relationship of CRF across the WC distribution was precluded. The purpose of this study was to comprehensively evaluate the association between CRF and the distribution of WC using quantile regression. Secondary data analysis was conducted using data from the 1999-2004 NHANES. Participants (n=8260) aged 12-49years with complete data on estimated maximal oxygen consumption and WC were included. Quantile regression models were performed to assess the association between CRF and the 10th, 25th, 50th, 75th and 90th WC percentiles and were adjusted for age and race/ethnicity. For male and female adolescents with high CRF compared to low-fit counterparts, significant negative estimates (2.8 to 20.2cm and 2.3 to 11.2cm, respectively) were observed across most WC percentiles. Similarly, among male and female adults, high CRF was associated with significant reductions in WC across all percentiles (9.5 to 12.0cm and 3.7 to 9.2cm, respectively). For both populations, an increasing trend in the magnitude of the association of high CRF across the WC percentiles was observed. CRF appears to have a differential relationship across the WC distribution with the largest reductions in WC were found among high-fit individuals with the greatest amount of central adiposity (WC≥90th percentile). Additionally, this differential association highlights the significant limitations of statistical techniques used in previous analyses which focused on the center of the distribution.

Persistence of Parent-Reported ADHD Symptoms From Childhood Through Adolescence in a Community Sample.

OBJECTIVE: To examine ADHD symptom persistence and factors associated with elevated symptom counts in a diverse, longitudinal community-based sample. METHOD: Parents reported demographics and completed a diagnostic interview repeatedly over a 6-year period. At Time 1, 481 interviews were completed about children (5-13 years); all participants were invited to four annual follow-up interviews, and 379 (79%) completed at least one. Inattentive (IA) and hyperactive-impulsive (HI) symptom counts were modeled with logistic quantile regression, while accounting for study design complexities. RESULTS: The prevalence of seven IA symptoms remained stable from early childhood through late adolescence. The prevalence of eight HI symptoms decreased by more than half over time. After demographic adjustment, the upper quartile of HI symptom counts decreased with age (p < .01). High HI symptom counts persisted more among those with high IA symptom counts (p = .05). CONCLUSION: This study further characterizes and provides insights into ADHD symptom trajectory through adolescence.

Association of complementary and alternative medicine use with symptoms and physical functional performance among adults with arthritis.

BACKGROUND: Research shows high prevalence of complementary and alternative medicine (CAM) use in individuals with arthritis. Little is known about CAM use and objectively measured physical functional performance. OBJECTIVE: The main objective was to determine if CAM use was associated with self-reported symptoms and physical functional performance in adults with arthritis. The secondary objectives were to describe the perceived helpfulness and correlates of CAM use. METHODS: We analyzed cross-sectional data from a self-administered questionnaire and objectively measured physical functional performance prior to randomization to a self-paced exercise program or control condition (n = 401). We used the Fisher's exact test, analysis of variance, and general linear models to examine the association of CAM use with socio-demographic characteristics, symptoms and functional performance. Logistic regression computed the odds of perceiving CAM as helpful by level of use. RESULTS: Most respondents had used CAM (76%). Dietary supplements were the most-used (53.1%). Female gender and college education predicted greater number of modalities used. Compared to non-users, use of any CAM was associated with greater fatigue and lower grip strength; relaxation techniques with lower walk distance and gait speed; dietary change with greater pain and stiffness and lower walk distance; and yoga with lower pain and stiffness, greater walk distance, chair stands, seated reach and gait, but lower grip strength. Perceived help was positively associated with the number of modalities used. CONCLUSIONS: Associations between CAM and symptoms or functional performance were mixed. Only yoga showed positive associations; however, yoga practitioners were more physically active overall than non-practitioners.

Objectively Measured Daily Steps and Subsequent Long Term All-Cause Mortality: The Tasped Prospective Cohort Study.

BACKGROUND: Self-reported physical activity has been inversely associated with mortality but the effect of objectively measured step activity on mortality has never been evaluated. The objective is to determine the prospective association of daily step activity on mortality among free-living adults. METHODS AND FINDINGS: Cohort study of free-living adults residing in Tasmania, Australia between 2000 and 2005 who participated in one of three cohort studies (n = 2 576 total participants). Daily step activity by pedometer at baseline at a mean of 58.8 years of age, and for a subset, repeated monitoring was available 3.7 (SD 1.3) years later (n = 1 679). All-cause mortality (n = 219 deaths) was ascertained by record-linkage to the Australian National Death Index; 90% of participants were followed-up over ten years, until June 2011. Higher daily step count at baseline was linearly associated with lower all-cause mortality (adjusted hazard ratio AHR, 0.94; 95% CI, 0.90 to 0.98 per 1 000 steps; P = 0.004). Risk was altered little by removing deaths occurring in the first two years. Increasing baseline daily steps from sedentary to 10 000 steps a day was associated with a 46% (95% CI, 18% to 65%; P = 0.004) lower risk of mortality in the decade of follow-up. In addition, those who increased their daily steps over the monitoring period had a substantial reduction in mortality risk, after adjusting for baseline daily step count (AHR, 0.39; 95% CI, 0.22 to 0.72; P = 0.002), or other factors (AHR, 0.38; 95% CI, 0.21-0.70; P = 0.002). CONCLUSIONS: Higher daily step count was linearly associated with subsequent long term mortality among free living adults. These data are the first to quantify mortality reductions using an objective measure of physical activity in a free living population. They strongly underscore the importance of physical inactivity as a major public health problem.

Gender differences in the association between food insecurity and insulin resistance among U.S. adults: National Health and Nutrition Examination Survey, 2005-2010.

PURPOSE: To examine gender-specific associations between food insecurity and insulin resistance in a representative U.S. METHODS: Data on 5533 adults of 20 years of age or more (2742 men and 2791 women) without diabetes from the 2005-2010 National Health and Nutrition Examination Survey were analyzed. Respondents were categorized as having full, marginal, low, or very low food security using a validated scale. Insulin-resistant individuals were defined as those with a homeostasis model assessment of insulin resistance value 2.5 or more. RESULTS: Insulin resistance was higher in both normal-weight (P = .001) and overweight or obese (P < .001) women with lower food security, but no linear trend was found in men. In multiple logistic regression analyses, however, very low food security-compared with full food security-was associated with insulin resistance in normal-weight men (odds ratio, 3.99; 95% confidence interval, 1.71-9.33), and marginal food insecurity was associated with insulin resistance in overweight or obese men (odds ratio, 2.07; 95% confidence interval, 1.18-3.64) after adjusting for potential confounders. In women, the association between food insecurity and insulin resistance was no longer significant after adjustment. CONCLUSIONS: Food insecurity is associated with insulin resistance in adults without diabetes, and this effect varies by gender in normal-weight and overweight or obese populations. Improving food security status may help reduce insulin resistance, an underlying risk factor for diabetes and cardiovascular disease.

New Perspective on Factors Related to Coalition Success: Novel Findings From an Investigation of Physical Activity Coalitions Across the United States.

CONTEXT: Physical activity (PA) coalitions are a fundamental component of efforts to increase population levels of PA in the United States. Coalitions are often composed of organizational members including government agencies, for-profit corporations, and nonprofit organizations. Very little is known about PA coalitions, their organizational members, and the factors related to their success. OBJECTIVE: First, this study aimed to describe the characteristics of PA coalitions across the United States. Second, the study aimed to describe the characteristics of organizational members of PA coalitions. Third, the study aimed to investigate the association between organizational membership and coalition success. DESIGN: A cross-sectional design was employed to study individuals from a diverse sample of PA coalitions across the United States. A total of 120 individuals (86% response rate) completed the Member Involvement in Physical Activity Coalitions (MIPAC) survey. The MIPAC included 3 sections: (1) demographic items assessing descriptive characteristics of PA coalitions and their organizational members; (2) 3 subscales for assessing key organizational membership factors (Strategic Alignment, Organizational Alignment, and Providing Input); and (3) 2 subscales for assessing perceived coalition success. MAIN OUTCOME MEASURES: Descriptive statistics characterize PA coalitions and their organizational members. Univariate analyses were employed to investigate associations between key organizational membership factors and perceived coalition success. RESULTS: Statistically significant associations were observed between the key organizational membership factors (Strategic Alignment, Organizational Alignment, and Providing Input) and measures of perceived coalition success. Many PA coalitions lacked organizational members from the settings in which the coalitions strive to make change. CONCLUSIONS: Physical activity coalitions and health-based coalitions overall may be more likely to succeed when they can identify ways in which their coalition provides opportunities for strategic alignment, organizational alignment, and providing input to existing and perspective organizational members. In addition, PA coalitions may benefit from engaging more organizational members from the built environment and education sectors.

Examining treatment adherence among parents of children with autism spectrum disorder.

BACKGROUND: Children with Autism Spectrum Disorder (ASD) participate in a variety of treatments, including medication, behavioral, alternative and developmental treatments. Parent adherence to these treatments is crucial for positive child outcomes. OBJECTIVE: The current study: 1) Explored patterns of parent adherence across the full range of treatments that are prescribed to children with ASD and, 2) Examined whether parent demographics, parent treatment attitudes, and child ASD severity contribute to parents' adherence across ASD treatments. METHOD: Questionnaires were distributed to parents of children with ASD in a southeastern state. Parents (N = 274) were included if they were parenting a child with ASD who was receiving treatment for ASD symptoms. Paired t-tests and multiple linear regression were used to assess the study aims. RESULTS: Adherence to medication treatment was significantly greater than adherence to behavioral, developmental, or alternative treatments (adjusted p-values 0.0006, 0.0030, 0.0006 respectively). Perceived family burden of a treatment was associated with lower adherence to medication, developmental, and alternative treatments. Finally, greater ASD severity was associated with lower adherence to alternative treatments. CONCLUSION: Overall, the independent variables accounted for more variance in adherence to medication and alternative treatments than in behavioral and developmental treatments. Parents' adherence to ASD treatment differs significantly by treatment type and is influenced by parental perceptions of the burden of treatment on the family. These findings highlight the importance of understanding and addressing the impact of ASD treatment regimens on family life.

Determinants of major cardiovascular risk factors among participants of the South Carolina WISEWOMAN program, 2009-2012.

INTRODUCTION: Cardiovascular disease (CVD) is the leading cause of death among US women, accounting for 25% of all deaths in this population. Approximately 65% of these deaths occur in asymptomatic women. Hypertension, hypercholesterolemia, and diabetes mellitus (diabetes) are major risk factors for CVD and can be treated effectively if identified at an early stage. METHODS: Data were available from 3,572 uninsured first-time female participants aged 40 to 65 years, referred by their health professional to the South Carolina Well-Integrated Screening and Evaluation for Women Across the Nation (SC WISEWOMAN), 2009-2012. All women completed a structured health-risk and behavior questionnaire. Anthropometric measures were recorded and data on clinical risk-factors were collected. Prevalence-ratios (PRs) were obtained by predictive multivariable log-linear modeling. RESULTS: The prevalence of risk factors was 34.7% for uncontrolled hypertension, 9.3% for hypercholesterolemia, and 21% for diabetes. Prevalence of untreated hypertension was 15.6%; hypercholesterolemia, 8%; and diabetes, 4%. The greatest significant predictor of hypercholesterolemia was hypertension (PR = 4.37) and vice versa (PR = 2.39). The greatest significant predictors of diabetes were obesity (PR = 2.23), family history of diabetes (PR = 2.02), and hypercholesterolemia (PR = 1.85). Being obese (PR = 1.36), overweight (PR = 1.23), aged 60 years or more (PR = 1.26), and black (PR = 1.14) were significant predictors of having at least one CVD risk factor. Being black (PR = 1.09) was the only significant predictor of having comorbid conditions. CONCLUSION: Prevalence of uncontrolled CVD risk factors was high among participants in the SC WISEWOMAN program. These findings confirm that the program is reaching high-risk women who are in need of interventions to reduce their risk for CVD through lifestyle changes.

Cardiorespiratory fitness, waist circumference, and alanine aminotransferase in youth.

PURPOSE: Nonalcoholic fatty liver disease (NAFLD) is considered the liver component of the metabolic syndrome and is strongly associated with cardiometabolic diseases. In adults, cardiorespiratory fitness (CRF) is inversely associated with alanine aminotransferase (ALT), a blood biomarker for NAFLD. However, information regarding these associations is scarce for youth. The objective of this study is to examine associations between CRF, waist circumference, and ALT in youth. METHODS: Data were obtained from youth (n = 2844, 12-19 yr) in the National Health and Nutrition Examination Survey 2001-2004. CRF was dichotomized into youth FITNESSGRAM categories of "low" and "adequate" CRF. Logistic and quantile regression were used for a comprehensive analysis of associations, and variables with previously reported associations with ALT were a priori included in the models. RESULTS: Results from logistic regression suggested that youth with low CRF had 1.5 times the odds of having an ALT >30 than youth with adequate CRF, although the association was not statistically significant (P = 0.09). However, quantile regression demonstrated that youth with low CRF had statistically significantly higher ALT (+1.04, +1.05, and +2.57 U·L) at the upper end of the ALT distribution (80th, 85th, and 90th percentiles, respectively) than youth with adequate CRF. For every 1-cm increase in waist circumference, the odds of having an ALT >30 increased by 1.06 (P < 0.001), and the strength of this association increased across the ALT distribution. CONCLUSIONS: Future studies should examine whether interventions to improve CRF can decrease hepatic fat and liver enzyme concentrations in youth with ALT ≥80th percentile or in youth diagnosed with NAFLD.

Co-varying patterns of physical activity and sedentary behaviors and their long-term maintenance among adolescents.

BACKGROUND: We examined the covarying patterns of physical activity and sedentary behaviors among adolescents and their long-term maintenance. METHODS: Data came from the National Longitudinal Study of Adolescent Health (1995-2002). We used latent class analysis to identify distinct covarying patterns in adolescence. Logistic regression models were used to predict odds of meeting moderate-to-vigorous physical activity (MVPA) recommendations (> or = 5 bouts/week) and exceeding screen time guidelines (> 2 hours/day) 6 years later based on their adolescent class profile. RESULTS: Five classes for each gender were identified and labeled as low physical activity (PA)/low sedentary behaviors (SED), moderate (Mod) PA/high (HI) SED, Mod PA/low SED, HI PA/low SED, and HI PA (except skating/biking)/low SED. Compared with low PA/low SED, males and females in Mod PA/low SED, HI PA/low SED, and HI PA (except skating/biking)/low SED classes had increased odds of meeting MVPA recommendations in young adulthood. Mod PA/HI SED had higher odds of exceeding screen time guidelines in young adulthood (adjusted odds ratio [AOR] for females: 1.67, 95% CI: 1.00-2.81; AOR for males: 3.31, 95% CI: 1.80-6.09). CONCLUSIONS: Findings are useful to aid the development of multifactorial interventions that promote physical activity and reduce screen time among adolescents transitioning to adulthood.