Longitudinal associations of screen time, physical activity, and sleep duration with body mass index in U.S. youth.

BACKGROUND: Youth use different forms of screen time (e.g., streaming, gaming) that may be related to body mass index (BMI). Screen time is non-independent from other behaviors, including physical activity and sleep duration. Statistical approaches such as isotemporal substitution or compositional data analysis (CoDA) can model associations between these non-independent behaviors and health outcomes. Few studies have examined different types of screen time, physical activity, and sleep duration simultaneously in relation to BMI. METHODS: Data were baseline (2017-2018) and one-year follow-up (2018-2019) from the Adolescent Brain Cognitive Development Study, a multi-site study of a nationally representative sample of U.S. youth (N = 10,544, mean [SE] baseline age = 9.9 [0.03] years, 48.9% female, 45.4% non-White). Participants reported daily minutes of screen time (streaming, gaming, socializing), physical activity, and sleep. Sex-stratified models estimated the association between baseline behaviors and follow-up BMI z-score, controlling for demographic characteristics, internalizing symptoms, and BMI z-score at baseline. RESULTS: In females, isotemporal substitution models estimated that replacing 30 min of socializing (ß [95% CI] = -0.03 [-0.05, -0.002]), streaming (-0.03 [-0.05, -0.01]), or gaming (-0.03 [-0.06, -0.01]) with 30 min of physical activity was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing (-0.03 [-0.05, -0.01]), streaming (-0.02 [-0.03, -0.01]), or gaming (-0.02 [-0.03, -0.01]) with 30 min of sleep was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing with 30 min of gaming was associated with a lower follow-up BMI z-score (-0.01 [-0.03, -0.0001]). CoDA estimated that in males, a greater proportion of time spent in baseline socializing, relative to the remaining behaviors, was associated with a higher follow-up BMI z-score (0.05 [0.02, 0.08]). In females, no associations between screen time and BMI were observed using CoDA. CONCLUSIONS: One-year longitudinal associations between screen time and BMI may depend on form of screen time, what behavior it replaces (physical activity or sleep), and participant sex. The alternative statistical approaches yielded somewhat different results. Experimental manipulation of screen time and investigation of biopsychosocial mechanisms underlying the observed sex differences will allow for causal inference and can inform interventions.

The longitudinal association of adipose-to-lean ratio with incident cardiometabolic morbidity: The CARDIA study.

AIM: To assess the association of adipose-to-lean ratio (ALR) with incident type 2 diabetes mellitus (T2DM), hypertension, and dyslipidemia in middle adulthood. METHOD: Black and White Coronary Artery Risk Development in Young Adults participants without T2DM, hypertension, or dyslipidemia in 2005-06 (baseline) were included. Baseline adipose and lean mass were assessed via dual-energy X-ray absorptiometry. ALR was calculated as adipose divided by lean mass and then standardized within sex strata. Single time-point incident morbidity was assessed every five years from baseline through 2016. Cox proportional hazards regression was used to estimate hazard ratios (HR) for morbidity over 10 years per 1-SD increment in ALR adjusted for cardiovascular risk factors. RESULT: The cumulative incidence of T2DM was 7.9 % (129 events/N = 1643; 16,301 person-years), 26.7 % (485 events/N = 1819; 17,895 person-years) for hypertension, and 49.1 % (435 events/N = 855, 8089 person-years) for dyslipidemia. In the adjusted models, ALR was positively associated with a risk of T2DM (HR [95 % CI]; 1.69 [1.31, 2.19]) and hypertension (1.23 [1.08, 1.40]). There was no significant interaction between ALR and sex for any morbidity. CONCLUSION: ALR in middle adulthood is associated with incident T2DM and hypertension. The extent to which localized body composition measures might inform morbidity risk merits further investigation.

Associations Between Estimates of Arterial Stiffness and Cognitive Functioning in Adults With HIV.

BACKGROUND: Vascular aging, a precursor of arterial stiffness, is associated with neurocognitive impairment (NCI) and cardiovascular disease. Although HIV is associated with rapid vascular aging, it is unknown whether arterial stiffness mediates changes in cognitive function. We explored whether estimated markers of vascular aging were associated with NCI indices in HIV-positive individuals. METHODS: This study was a secondary analysis of an observational study. Neurocognitive functioning was assessed using a battery of 7 domains (verbal fluency, executive functioning, speed of information processing, attention/working memory, memory [learning and delayed recall], and motor skills). Vascular aging was assessed using estimated markers of arterial stiffness (ie, estimated pulse wave velocity, pulse pressure, and vascular overload index). A multivariable regression adjusted for demographics, cardiovascular disease risk factors, and HIV clinical variables was used to examine the association between vascular aging and NCI outcomes. RESULTS: Among 165 people with HIV, the mean age was 51.5 ± 6.9 years (62% men and 83% African American/Black or Other). In fully adjusted models, an increase in estimated pulse wave velocity and pulse pressure was associated with lower T scores in learning (-2.95 [-5.13, -0.77]) and working memory (-2.37 [-4.36, -0.37]), respectively. An increase in vascular overload index was associated with lower T scores in working memory (-2.33 [-4.37, -0.29]) and learning (-1.85 [-3.49, -0.21]). CONCLUSIONS: Estimated markers of arterial stiffness were weakly associated with neurocognitive functioning, suggesting that vascular aging may have a role in cognitive decline among people with HIV.

External Training Load Monitoring and the Impact on Training Load Management in Collegiate Male Soccer Players.

ABSTRACT: Gdovin, JR, Galloway, R, Tomasiello, LS, Seabolt, M, and Booker, R. External training load monitoring and the impact on training load management in collegiate male soccer players. J Strength Cond Res 37(7): 1434-1439, 2023-Soccer is a physically demanding sport within the National Collegiate Athletic Association and continuously increases in popularity. To ensure athletes are adequately prepared for weekly physical stressors, coaches can use global positioning system technology to monitor external workloads and exercise intensity. These data can subsequently help coaches and practitioners better implement individualized training programs to ensure athletes are properly balancing the overreaching and overtraining paradigm. Therefore, the purpose of this observational study was to retrospectively analyze 3 consecutive seasons of external workload (total and high intensity distance) and injury data, which were derived from all training sessions and matches in 46 Division-I collegiate male soccer players. A coach's interpretation sought to provide practical insight into the functionality behind load management and how it prepares athletes for the physical stressors placed on them throughout a season. Two separate 3 × 3 repeated measures ANOVAs were conducted to determine differences between total distance and distance at high-intensity with an alpha level set at 0.05. Total distance between preseason and in-season ( p = 0.003), acute high-intensity distance ( p < 0.001), and chronic high-intensity distance ( p < 0.001) yielded significant differences. These results conclude the demands of each athlete change weekly and between seasons. It is recommended that sport coaches and practitioners develop individualized training programs by workload monitoring while considering variables such as a team's style of play, experience, position, role within a program, training intensity, and the length of time between conditioning sessions, practices, and matches.

Differences between preemptive and non-preemptive physical activity among 'drunkorexia'-positive college students.

Objective: 'Drunkorexia' is characterized by compensating for alcohol-related calories using physical activity (PA). Drunkorexia is common on college campuses but little is known about the PA behaviors within the drunkorexia paradigm. Methods: First-year college students living on campus completed an online survey collecting drunkorexia, PA, and alcohol consumption data. A total of 127 participants reported engaging in drunkorexia behaviors. Results: Fifty-three participants were classified as preemptively physically active (e.g., PA and drink on Tuesday) compared to 74 as non-preemptively physically active. Preemptively physically active participants consumed more alcohol on Fridays and Saturdays than those non-preemptively physically active. Preemptively physically active participants engaged in significantly greater amounts PA. Females accounted for all significant differences between groups. Discussion: Among drunkorexia-positive participants, many made preemptive efforts to control their calories before consuming alcohol, which may predispose them to higher incidences of adverse outcomes such as alcohol poisoning, unwanted sexual advances, and death.

Compositional analysis of movement behaviors' association on high-sensitivity c-reactive protein: the Jackson heart study.

PURPOSE: Movement behaviors (i.e. physical activity [PA], sedentary behavior [SB], and sleep) are intrinsically codependent, an issue resolved using compositional data analysis (CoDA). High-sensitivity C-reactive protein (hs-CRP) is a nonspecific inflammatory marker positively associated with cardiovascular diseases and affected by movement behaviors. Examine the relation between movement behaviors using CoDA and how time reallocation between two movement behaviors was associated with hs-CRP concentration. METHODS: The Jackson Heart Study was designed to investigate cardiovascular disease risk factors among African American participants in the Jackson, MS area. PA and sleep were self-reported with SB calculated as the remaining time in the day. RESULTS: The median untransformed hs-CRP concentration was 0.28 mg·dL-1 (interquartile range; 0.11, 0.61). Reallocating 15 minutes of PA with SB, the hypothetical change in log hs-CRP concentration was 0.08 mg·dL-1 (95% CIs; 0.04, 0.11) greater than the average log hs-CRP concentration. Substituting 15 minutes of SB or sleep with PA was associated with a hypothetical change in log hs-CRP concentration difference of -0.05 mg·dL-1 (-0.08, -0.03) and -0.06 mg·dL-1 (-0.08, -0.03), respectively. Reallocations between SB and sleep were not associated with the hypothetical difference in log hs-CRP concentration. CONCLUSIONS: Modeling estimates suggest replacing 15 minutes of SB with PA is associated with lower inflammation.

Comparison of Leisure Time Physical Activities by Metabolic Syndrome Status among Adolescents.

Background: Metabolic syndrome (MetS) increases the risk of premature morbidity and mortality. Physical activity (PA) beneficially affects MetS; however, it is unclear if PA types differ among adolescents 12-15 years old, according to their MetS status. This study compared self-reported PA types by MetS status. Methods: Using the 2015-2016 National Health and Nutritional Examination Survey (NHANES) data, 664 adolescents self-reported PA in the past seven days. MetS status was assessed using Ford's pediatric adaptation of the ATP-III adult criteria. Pearson chi-square and t-tests were conducted to determine self-reported PA differences. Results: The adolescents' mean age was 13.47 years (95% CIs; 13.04, 14.38) and 52.69% were male (352). Twenty-seven (4.07%) adolescents were MetS positive. The prevalence of PA engagement in the past seven days was similar for MetS-positive and -negative adolescents (77.67% and 70.51%, respectively; p > 0.05). No significant differences were observed for PA type by MetS status. MetS-positive adolescents reported higher sedentary time (565.77 [438.99, 692.56] vs. 490.59 [377.86, 603.33] minutes per day, respectively; p = 0239). Conclusions: Engagement in specific PA types does not appear to differ by MetS status, but MetS-positive adolescents have significantly higher sedentary time. PA promotion should target a variety of activities to maximize the effectiveness of public health programs and interventions should target reducing sedentary time.

Relationship between physical activity intensities and drunkorexia severity among first-year college students.

OBJECTIVE: Investigate the relationship between intensities of physical activity and severity of drunkorexia behaviors. Participants: First-year college students living in residence halls (n = 127) completed an online survey comprising drinking, drunkorexia, and physical activity. Methods: Multiple hierarchical linear regressions were implemented to examine if physical activity intensity correlates to drunkorexia severity. Results: Vigorous physical activity was the only physical activity intensity significantly associated with severity of drunkorexia behaviors. Conclusions: First-year college students' duration of vigorous physical activity in relation to severity of drunkorexia behaviors may vary contingently on the motivation for vigorous physical activity. Practitioners need to consider physical activity can be a co-occurring risk behavior in combination with alcohol misuse.

Defibrillation with a minimally invasive direct cardiac massage device.

OBJECTIVE: This study examined (1) the defibrillation efficacy of using a minimally invasive direct cardiac massage (MID-CM) device as one electrode of the defibrillation electrical circuit and (2) the effect on external defibrillation of defibrillating when the MID-CM device is in place and a pneumothorax is present. METHODS: Part 1: in seven pigs, defibrillation thresholds (DFTs) were determined with a truncated exponential biphasic waveform. DFTs were determined for five electrode configurations: standard transthoracic defibrillation with electrodes on the left and right chest walls (1), with the MID-CM as one of the defibrillation electrodes pressed gently (2) or firmly (3) against the heart with the right chest wall patch as the second electrode, the same as (1) with the MID-CM device in place and the lungs at end-inspiration (4) or at end-expiration (5). Part 2: in six pigs, DFTs were determined with a monophasic damped sinusoidal waveform with external defibrillation electrodes (1) and with the device as one defibrillation electrode and the other electrode on either the anterior (2), lateral (3), or posterior right chest wall (4). RESULTS: Part 1: the DFTs for (2) or (3) were not different (18.7+/-12.4 vs. 17.0+/-8.3 J), but both DFTs were lower than that for (1) (155+/-45 J). The DFT was elevated for (4) (205+/-69 J) compared with (1). For (5) only one animal could be defibrillated with shocks up to 360 J. Part 2: the DFTs for (2), (3) or (4) were not different (19.5+/-11.0, 25.4+/-9.4, 27.4+/-9.0 J), but all three were lower than the DFT for (1) (198+/-70 J). CONCLUSIONS: Using the MID-CM device as one electrode of the defibrillation circuit markedly lowers the DFT compared with that for standard transthoracic defibrillation for both a monophasic and biphasic waveform. Defibrillation with the device in place and the chest opened elevates the DFT for external defibrillation much more during end-expiration than during end-inspiration.