This study investigated the effect of the racemic β-hydroxybutyrate (βHB) precursor, R,S-1,3-butanediol (BD), on time-trial (TT) performance and tolerability. A repeated-measures, randomized, crossover study was conducted in nine trained male cyclists (age, 26.7 ± 5.2 years; body mass, 69.6 ± 8.4 kg; height, 1.82 ± 0.09 m; body mass index, 21.2 ± 1.5 kg/m2; VO2peak,63.9 ± 2.5 ml·kg−1·min−1; W max, 389.3 ± 50.4 W). Participants ingested 0.35 g/kg of BD or placebo 30 min before and 60 min during 85 min of steady-state exercise, which preceded a ∼25- to 35-min TT (i.e., 7 kJ/kg). The ingestion of BD increased blood D-βHB concentration throughout exercise (0.44–0.79 mmol/L) compared with placebo (0.11–0.16 mmol/L; all p < .001), which peaked 1 hr following the TT (1.38 ± 0.35 vs. 0.34 ± 0.24 mmol/L; p < .001). Serum glucose and blood lactate concentrations were not different between trials (all p > .05). BD ingestion increased oxygen consumption and carbon dioxide production after 20 min of steady-state exercise (p = .002 and p = .032, respectively); however, no further effects on cardiorespiratory parameters were observed. Within the BD trial, moderate to severe gastrointestinal symptoms were reported in five participants, and low levels of dizziness, nausea, and euphoria were reported in two participants. However, this had no effect on TT duration (placebo, 28.5 ± 3.6 min; BD, 28.7 ± 3.2 min; p = .62) and average power output (placebo, 290.1 ± 53.7 W; BD, 286.4 ± 45.9 W; p = .50). These results suggest that BD has no benefit for endurance performance.
David M. Shaw, Fabrice Merien, Andrea Braakhuis, Daniel Plews, Paul Laursen and Deborah K. Dulson
Ralph Beneke and Renate M. Leithäuser
Maureen R. Weiss, Lindsay E. Kipp, Alison Phillips Reichter, Sarah M. Espinoza and Nicole D. Bolter
Purpose: Girls on the Run is an after-school physical activity-based positive youth development program designed to enhance girls’ social, psychological, and physical development. We evaluated the effectiveness of the program by employing a longitudinal design and mixed methods. Methods: Girls (N = 203; aged 8–11 y) completed survey measures of positive youth development constructs (competence, confidence, connection, character, and caring), physical activity, and sedentary behavior prior to, at the end of, and 3 months after the season. Subsamples of girls, coaches, caregivers, and school personnel participated in focus groups. Coaches completed information about their team’s community impact project and number of girls who completed the season-ending 5k. Results: The full sample improved in confidence and connection, whereas girls who started below the preseason average showed the greatest gains from preseason to postseason on all measures, and scores were maintained or continued to improve at follow-up. All stakeholders in focus groups corroborated evidence of season-long improvement in social and emotional behaviors and health outcomes. Involvement in the community impact project contributed to girls’ growth in character and empathy skills. Conclusion: Findings provide empirical evidence that Girls on the Run is effective in promoting positive youth development, including season-long and lasting change in competence, confidence, connection, character, caring, and physical activity, especially among girls who exhibited lower preseason scores than their peers.
Ina M. Tarkka, Pekka Hautasaari, Heidi Pesonen, Eini Niskanen, Mirva Rottensteiner, Jaakko Kaprio, Andrej M. Savić and Urho M. Kujala
Background: Physical activity (PA) is said to be beneficial to many bodily functions. However, the effects of PA in the brain are still inadequately known. The authors aimed to uncover possible brain modulation linked with PA. Here, they combine 4 of their studies with monozygotic twins, who were within-pair discordant in PA for a minimum of 1 year. Methods: The authors performed brain imaging, brain electrophysiology, and cardiovascular and body composition assessments, and collected questionnaire-based data. The present synopsis elucidates the differences associated with differing PA history in conditions without genetic variability. They present new structural and electrophysiological results. Participants, healthy, 45 male monozygotic twins (mean age 34.5 [1.5] y) differed in aerobic capacity and fat percentage (P < .001). Results: More active co-twins showed larger gray matter volumes in striatal, prefrontal, and hippocampal regions, and smaller gray matter volumes in the anterior cingulate area than less active co-twins. Functionally, visual and somatosensory automatic change detection processes differed between more and less active co-twins. Conclusions: In monozygotic twins, who differed in their PA history, differences were observed in identifiable anatomic brain locations involved with motor control and memory functions, as well as in electrophysiological measures detecting brain’s automatic processes. Better aerobic capacity may modify brain morphology and sensory function.
Dawn C. Mackey, Alexander D. Perkins, Kaitlin Hong Tai, Joanie Sims-Gould and Heather A. McKay
We conducted Men on the Move, a 12-week randomized controlled feasibility trial of a scalable, choice-based, physical activity (PA) and active transportation intervention. Participants were community-dwelling men aged 60 years and older (n = 29 intervention [INT] and n = 29 waitlist control [CON]). Trained activity coaches delivered: (a) one-on-one participant consultations to develop personal action plans for PA and active transportation, (b) monthly group-based motivational meetings, (c) weekly telephone support, (d) complimentary recreation and transit passes, and (e) pedometers and diaries for self-monitoring. Men on the Move demonstrated high rates of recruitment, retention, and intervention adherence. INT chose a variety of group-based and individual PAs and destinations for their personal action plans. At 12 weeks, INT achieved more steps, moderate–vigorous PA, and energy expenditure than CON. INT was also more likely to take transit and meet national guideline levels of PA. At 24 weeks follow-up, INT benefits were sustained for moderate–vigorous PA and energy expenditure.
Diego G.D. Christofaro, Bruna C. Turi-Lynch, Kyle R. Lynch, William R. Tebar, Rômulo A. Fernandes, Fernanda G. Tebar, Gregore I. Mielke and Xuemei Sui
Background: This study investigated associations between different types of sedentary behavior (SB) and physical activity (PA) in parent and their child, including the moderating effects of parent and child sex. Methods: In total, 1231 adolescents, 1202 mothers, and 871 fathers were evaluated. The SB (TV viewing + computer + video game); different types of PA (leisure-time PA, occupational PA, and total PA); and the socioeconomic level were evaluated by questionnaire. The relationship between adolescents’ SB and PA with parental characteristics was estimated by linear regression. Results: The SB of male adolescents was correlated to the father’s SB (β = 0.26; 95% confidence interval [CI], 0.13–0.39) and mother’s SB (β = 0.18; 95% CI, 0.06–0.31). A similar relationship was observed between SB of female adolescents and the father’s SB (β = 0.31; 95% CI, 0.19–0.42) and mother’s SB (β = 0.29; 95% CI, 0.20–0.38]). The SB of girls was inversely related to mother’s occupational PA (β = −2.62; 95% CI, −3.66 to −0.53]). The PA of the boys and girls was correlated with their fathers and mothers PA. All the results were adjusted for age and parent’s socioeconomic level. Conclusions: SB and PA of parents were associated with SB and PA of their children, regardless of gender. Strategies for health promotion should consider the family environment to increase PA and reduce SB.
Samuel D. Muir, Sandun S.M. Silva, Mulu A. Woldegiorgis, Hayley Rider, Denny Meyer and Madawa W. Jayawardana
Background: Despite holding great potential for addressing concerns regarding public health, recent systematic reviews have found effect sizes for interventions targeting physical activity to be small. Before interventions can be improved, the factors influencing outcomes must be identified. This systematic review aimed to identify predictors of success, measured in terms of engagement (eg, involvement duration) and health behavior change (eg, increased step counts), of workplace interventions targeting physical activity. Methods: A structured search of 3 databases (PubMed, PsycINFO, and Web of Science) was conducted to identify articles published between January 2000 and April 2017. For inclusion, articles needed to test a workplace intervention targeting physical activity and perform a quantitative analysis, identifying predictors of engagement or health behavior change. Results: Twenty-two studies were identified for review (median quality score = 70%). Demographic variables (eg, gender, age) were inconsistent predictors of success. However, employees in better health and physically active at baseline were found to have a greater likelihood of success. Conclusions: It appears that achieving successful results among employees at high risk of poor health outcomes remains a significant challenge for interventions. It is hoped that program developers can use this information to create effective interventions particularly for more sedentary employees.