LETM1-Mediated K+ and Na+ Homeostasis Regulates Mitochondrial Ca2+ Efflux

HIGHLIGHTS \u2022 Monovalent cation homeostasis is dysregulated upon LETM1 depletion \u2022 K+/H+ exchange activity is decreased in LETM1 knockdown cells \u2022 LETM1 depletion results in K+ accumulation in the mitochondrial matrix \u2022 LETM1 knockdown does not affect expression of major mitochondrial Ca2+ transport modulators \u2022 LETM1-regulated mitochondrial Ca2+ fluxes are dependent on Na+ Ca2+ transport across the inner membrane of mitochondria (IMM) is of major importance for their functions in bioenergetics, cell death and signaling. It is therefore tightly regulated. It has been recently proposed that LETM1\u2014an IMM protein with a crucial role in mitochondrial K+/H+ exchange and volume homeostasis\u2014also acts as a Ca2+/H+ exchanger. Here we show for the first time that lowering LETM1 gene expression by shRNA hampers mitochondrial K+/H+ and Na+/H+ exchange. Decreased exchange activity resulted in matrix K+ accumulation in these mitochondria. Furthermore, LETM1 depletion selectively decreased Na+/Ca2+ exchange mediated by NCLX, as observed in the presence of ruthenium red, a blocker of the Mitochondrial Ca2+ Uniporter (MCU). These data confirm a key role of LETM1 in monovalent cation homeostasis, and suggest that the effects of its modulation on mitochondrial transmembrane Ca2+ fluxes may reflect those on Na+/H+ exchange activity

Factors Related to Objectively Measured Physical Activity in Preschool Children

This study examined correlates of objectively measured physical activity (PA) in a diverse sample of preschool children (age 3–5 years; n=331). Accelerometer min·hr−1 of moderate-to-vigorous physical activity (MVPA) and non-sedentary activity (NSA) were the outcome measures. Correlations among potential correlates and PA ranged from r= − .12–0.26. Correlates in the final MVPA model were age, race, sex, BMI Z score, and parent perception of athletic competence, explaining 37% of the variance. The NSA model included the latter two variables, explaining 35% of the variance. Demographic factors were correlates of PA; parent perceptions of children’s competence may be important regarding preschoolers’ PA. Originally published Pediatric Exercise Science, Vol. 21, No. 2, May 200

Associations among Physical Activity, Health Indicators, and Employment in 12th Grade Girls

Objectives: This study compared physical activity, sedentary behaviors, and other health indicators between 1381 employed and nonemployed 12th grade girls. Methods: The girls were from 22 high schools in South Carolina (2002-2003); 56% of the girls were African American, and the mean age was 17.7 (0.6) years. Physical activity and sedentary behaviors were measured using the 3-Day Physical Activity Recall (3DPAR). Fitness, depressive symptoms, and smoking behavior were assessed. Results: Fifty percent of the girls were employed, and on average, employed girls worked 9.6 30-minute blocks per day. Girls who worked reported significantly (p≤0.001) higher average total metabolic equivalents (METs) (mean [M] 66.4, SE 0.5) than girls who did not work (M 59.5, SE 0.5). Also, a higher percent of girls who worked reported 2+ blocks of moderate to vigorous physical activity (MVPA) (89.3%), and fewer (20.2%) reported 4+ blocks of electronic media (EM) compared with girls who did not work (MVPA 62.7%, EM 41.7%). After on-the-job activity was subtracted, total METs for girls who worked was reduced to 48.0 (SE 0.4), and only 48.5% reported 2 or more blocks on average of MVPA. No significant differences (p\u3e0.05) were found between girls who reported working (W) and those who did not (NW) for body mass index (BMI) (W: M 25.2, SE 0.2; NW: M 24.6, SE 0.2), depression scores (W: M 14.4, SE 0.5); NW: M 14.4, SE 0.5), fitness (W: M 11.3 kg ● m/min/kg, SE 0.2; NW: M 11.7 kg ● m/min/kg, SE 0.2), or smoking during the past 30 days (W: 18.5%; NW: 17.4%). Conclusions: Nearly one third of employed high school girls\u27 total physical activity occurred while they were at work. Employed girls also spent less time using electronic media. Employment was not associated with fitness, smoking, or depressive symptoms in 12th grade girls

Raw and Count Data Comparability of Hip-Worn ActiGraph GT3X+ and Link Accelerometers

To enable inter- and intrastudy comparisons it is important to ascertain comparability among accelerometer models. Purpose: The purpose of this study was to compare raw and count data between hip-worn ActiGraph GT3X+ and GT9X Link accelerometers. Methods: Adults (n = 26 (n = 15 women); age, 49.1 T 20.0 yr) wore GT3X+ and Link accelerometers over the right hip for an 80-min protocol involving 12–21 sedentary, household, and ambulatory/exercise activities lasting 2–15 min each. For each accelerometer, mean and variance of the raw (60 Hz) data for each axis and vector magnitude (VM) were extracted in 30-s epochs. A machine learning model (Montoye 2015) was used to predict energy expenditure in METs from the raw data. Raw data were also processed into activity counts in 30-s epochs for each axis and VM, with Freedson 1998 and 2011 count-based regression models used to predictMETs. Time spent in sedentary, light, moderate, and vigorous intensities was derived from predicted METs from each model. Correlations were calculated to compare raw and count data between accelerometers, and percent agreement was used to compare epoch-by-epoch activity intensity. Results: For raw data, correlations for mean acceleration were 0.96 T 0.05, 0.89 T 0.16, 0.71 T 0.33, and 0.80 T 0.28, and those for variance were 0.98 T 0.02, 0.98 T 0.03, 0.91 T 0.06, and 1.00 T 0.00 in the X, Y, and Z axes and VM, respectively. For count data, corresponding correlations were 1.00 T 0.01, 0.98 T 0.02, 0.96 T 0.04, and 1.00 T 0.00, respectively. Freedson 1998 and 2011 count-based models had significantly higher percent agreement for activity intensity (95.1% T 5.6% and 95.5% T 4.0%) compared with theMontoye 2015 raw data model (61.5% T 27.6%; P G 0.001). Conclusions: Count data were more highly comparable than raw data between accelerometers. Data filtering and/or more robust raw data models are needed to improve raw data comparability between ActiGraph GT3X+ and Link accelerometers

Health-Related Fitness and Energy Expenditure in Recreational Youth Rock Climbers 8-16 Years of Age

International Journal of Exercise Science 8(2): 174-183, 2015. Information on the characteristics of youth rock climbers is minimal. The purpose was to 1) Determine the influence of a three-month program of bouldering and vertical rock climbing on the anthropometry and health-related physical fitness of relatively novice youth climbers, and 2) determine whether rock climbing and bouldering in novice youth climbers can provide adequate levels of moderate to vigourous physical activity (US DHHS, 2008). Fifteen participants (11 males and 4 females; mean age = 11.5 ± 2.3 years) from a newly established youth climbing team were assessed twice weekly during their normal two-hour training sessions at a local rock gym. Body composition, flexibility, grip strength, and anthropometric estimates of somatotype were measured in August and November. Heart rate (HR) monitors recorded average activity heart rate (AHR), peak heart rate (HRpeak), and estimated energy expended (EE-kcals) during each climbing session. Basic descriptive statistics were run; repeat measure ANOVAs were used to assess changes between times. Estimated percent body fat did not change, but individual skinfolds (biceps and supraspinale) decreased significantly (

Examining the Role of Churches in Adolescent Girls\u27 Physical Activity

Background: In adults, associations between church attendance and positive health behaviors exist; however, similar evidence among children and youth is lacking. The purposes of this investigation were to examine the associations between physical activity (PA) and church attendance, PA and use of church as a PA facility, and PA and proximity to churches among those who use church as a PA facility (while addressing racial and geographic differences). Methods: High school girls (N=915, age=17.7 ± 0.6 years, 56% African American) completed the 3-Day Physical Activity Recall and surveys including demographics and use of PA facilities. Geographic Information Systems data were used to spatially examine the number of churches within a 0.75-mile street network buffer around girls\u27 homes. Associations were examined using mixed model analyses controlling for demographic factors. Results: For the overall sample, total METs (56 versus 52) and proportion of girls meeting PA guidelines (62% vs. 52%) were significantly higher in church attendees versus nonattendees. Among participants who used facilities, having more churches close to home was associated with more PA. Conclusions: Church attendance and use are correlates of physical activity that should be further explored and addressed in future intervention research with adolescent girls

A Pilot, Virtual Exercise Intervention Improves Health and Fitness during the COVID-19 Pandemic

International Journal of Exercise Science 15(7): 1395-1417, 2022. Physical activity levels are low in individuals with chronic disease (e.g., obesity) and have worsened during the COVID-19 pandemic. Purpose: Our pilot study tested a virtual exercise intervention for rural-dwelling adults with chronic disease from January-April 2021 for changes in mental health, physical fitness, and physical activity and for intervention fidelity. Methods: Participants (n = 8 [7 female]; age = 57.5 ± 13.8 years, body mass index = 38.2 ± 8.0 kg/m2) completed an exercise intervention led virtually by collegiate health science majors. Participants attended two 60-minute sessions/week for 12 weeks, completing individually-tailored and progressed aerobic and muscle-strengthening training. A non-randomized control group matched on gender and age continued normal activity during the 12 weeks. Changes in mental health, physical fitness, and physical activity measures were evaluated using a 2x2 (group x time) analysis of covariance. Results: Both groups improved mental health, but only intervention participants lost weight (3.1 ± 1.0 kg; no change in controls). Step test, arm curls, and chair stands improved by 16.1-20.6% in the intervention and 7.8-12.1% in the control groups. Intervention participants did not increase overall physical activity during or after the intervention. Intervention fidelity was high; participants attended ~73% of sessions and rated the sessions 4.7 ± 0.6 (out of 5). Researcher observations rated exercise sessions as meeting 12.7 ± 0.6 of 16 goals. Conclusions: Our virtual exercise program was associated with positive mental health and physical fitness changes. Such programs may provide a method, even beyond the pandemic, to improve fitness in adults with chronic disease

Social and Environmental Factors Associated with Preschoolers' Non-sedentary Physical Activity

The two-fold purpose of the investigation was (1) to describe with direct observation data the physical activity behaviors and the accompanying social and environmental events of those behaviors for children in preschools; and (2) to determine which contextual conditions were predictors of moderate-to-vigorous physical activity (MVPA) and non-sedentary physical activity (i.e., light activity + MVPA) for 3-, 4-, and 5-year-old children during their outdoor play. The results indicate that preschoolers' physical activity is characterized as sedentary in nature throughout their preschool day (i.e., 89% sedentary, 8% light activity, 3% MVPA). During outdoor play periods, when children are most likely to be physically active, some contextual and social circumstances better predict their physical activity. Implications for policymakers, practitioners, and researchers are discussed. Originally published Child Development, Vol. 80, No. 1, Jan/Feb 200

“Girls on the Move” intervention protocol for increasing physical activity among low-active underserved urban girls: a group randomized trial

Abstract Background Increasing moderate to vigorous physical activity among urban girls of low socioeconomic status is both a challenge and a public health priority. Physical activity interventions targeting exclusively girls remain limited, and maintenance of moderate to vigorous physical activity during the post-intervention period has been difficult to maintain. The main aim of the 5-year “Girls on the Move” group randomized trial is to evaluate the efficacy of a comprehensive school-based intervention in increasing girls’ minutes of moderate to vigorous physical activity and improving cardiovascular fitness, body mass index, and percent body fat immediately post-intervention (after 17 weeks) and at 9-month post-intervention follow-up (9 months after end of intervention). Methods/Design A total of 24 urban middle schools in the Midwestern U.S. will be randomized to either receive the intervention or serve as a control (N = 1200 girls). The intervention, based on the Health Promotion Model and Self-Determination Theory, will include: (1) two face-to-face motivational, individually tailored counseling sessions with a registered nurse, one at the beginning and the other at the end of the intervention period; (2) an interactive Internet-based session during which each girl receives individually tailored motivational and feedback messages via iPad at 11 weeks (shortly after midpoint of intervention); and (3) a 90-minute after-school physical activity club. Racially diverse, low-active, 10- to 14-year-old 5th to 8th-grade girls will complete questionnaires and physical measures at baseline and post-intervention (n = 50 per school). Minutes of moderate to vigorous physical activity will be assessed with accelerometers. Cardiovascular fitness will be assessed by estimating VO2 max with PACER (Progressive Aerobic Cardiovascular Endurance Run) scores. Height and weight will be assessed to calculate body mass index. Percent body fat will be estimated with a foot-to-foot bioelectric impedance scale. Linear mixed effects regression analyses will be performed to assess intervention effects. Discussion This multi-component approach is expected to improve girls’ moderate to vigorous physical activity and related physical outcomes. Trial Registration ClinicalTrials.gov Identifier NCT01503333http://deepblue.lib.umich.edu/bitstream/2027.42/112470/1/12889_2013_Article_5394.pd