Aerobic and skeletal muscle architectural adaptations to concurrent marathon and circuit resistance training

Purpose: The purpose of this investigation was to examine performance-related physiological adaptations (VO2max, Lactate Threshold, and Running Economy) and skeletal muscle architectural changes (muscle thickness, pennation angle, and fascicle length) of the vastus lateralis (VL) and lateral gastrocnemius (LG) to marathon training with and without a concurrent circuit resistance-training program. Methods: Thirteen subjects (21 ± 1 yrs, 171 ± 2 cm, 65 ± 2 kg, 55 ± 2 ml/kg/min) completed a 15-week progressive marathon-training program. Nine subjects completed the 15 weeks of progressive marathon-training alone (AE), while 4 subjects participated in the 9-week circuit training program (CONC), in addition to the run training. VO2max, lactate threshold, running economy, muscle thickness, pennation angle and fascicle length were assessed before and after training. 2x2 repeated measures ANOVAs and Wilcoxon Signed-Rank Tests were used to test the effects of the concurrent training intervention (AE vs. CONC) and general training program (pre vs. post training). Pearson correlations were utilized to examine relationships between changes in architectural and cardiovascular/metabolic parameters. Results: Absolute VO2max (L/min) increased in ALL with training (3.58 ± 0.18 vs. 3.73 ± 0.22; p=0.018), with a 9% increase in CONC (3.52 ± 0.38 L/min vs. 3.87 ± 0.50 L/min; p=0.031) and no change in AE. Lactate threshold increased significantly in ALL post-training (12.4 ± 0.3 kph vs. 13.2 ± 0.3 kph; p=0.012), with no differences between groups. There were no changes in running economy [submax VO2 (ml/kg/min]. LG pennation angle increased in ALL (17± 1.0°; p=0.056), with no differences between groups, while VL pennation angle did not change. There were no changes in muscle thickness or fascicle length in the VL or LG. Conclusion: Notwithstanding the small sample size, concurrent marathon and circuit training appears to increase absolute VO2max to a greater extent than marathon training alone. Marathon training increases LG pennation angle, and the change is not influenced by concurrent circuit resistance training. These findings suggest that that it can be beneficial for beginning marathon runners to supplement with concurrent circuit training programs, and that LG pennation angle is highly sensitive to endurance run training

Feasibility of a combined physical activity and sleep education intervention for girls living in a low socioeconomic status urban community

Declining sleep duration and poor sleep quality is a public health epidemic disproportionately effecting elementary age girls living in low socioeconomic status urban communities. The Girls Dancing and Sleeping for Health (Girls DASH) program was designed to test the feasibility, acceptability, and efficacy of a combined physical activity and sleep education program in this population. In combination with baseline data from a previously conducted intervention in elementary age urban girls living in a low SES community in Springfield, MA, results from a cross-sectional analysis indicated that greater screen time was positively associated with parental reports of child’s sleep quality. Additionally, children who got more physical activity had fewer and shorter accelerometer-derived nighttime awakenings and minutes spent in bed. Subsequently, the process evaluation data from the Girls DASH program indicated several roadblocks in recruitment, retention, implementation, and attaining outcome measurements. However, there were aspects of the intervention, such as screen time education from the sleep education program, homework tutoring, after-school care and health education which participants deemed highly acceptable. Due to a high occurrence of missing data, it is difficult to draw conclusions regarding the efficacy of the intervention in improving sleep and physical activity. Judging from the available data, the intervention improved total moderate-to-vigorous physical activity significantly in the intervention groups vs. control. Additionally, there were improvements in after-school physical activity, parent-reported sleep duration and accelerometer-derived minutes spent in bed in all participants over time, with no differences between groups. The results from this study can be used to improve the feasibility, acceptability and potential efficacy of future interventions seeking to improve sleep and physical activity in elementary age girls living in low socioeconomic status urban communities

No Change in Executive Function or Stress Hormones Following a Bout of Moderate Treadmill Exercise in Preadolescent Children

International Journal of Exercise Science 13(5): 1650-1666, 2020. Several studies suggest that acute bouts of exercise improve executive function in preadolescent children. However, the mechanisms underlying these effects are not completely understood. Specifically, no studies have examined the relationship between the stress hormone response to exercise and improvements in executive function in preadolescent children. The purpose of this study was to examine the effects of a bout of moderate intensity exercise versus rest on working memory (List Sorting Working Memory Task) and selective inhibition/attention (Eriksen flanker task) in preadolescent children, as well as to investigate whether changes in stress hormones (salivary cortisol and alpha-amylase) could explain any differences in performance on these tasks. Twenty-four children completed both a 30-minute moderate intensity bout of treadmill walking and seated rest in a laboratory setting. Tests of executive function and salivary stress hormone analyses were completed before and after each condition. 2x2 Repeated Measures ANOVAs were used to test the effects of time, condition, and time*condition on all executive function and hormonal outcomes. Linear regression models were used to determine if changes in executive function measures were related to changes in stress hormones in the exercise condition. Likely due to methodological limitations, there were no effects of time, condition, nor an interactive effect on working memory, selective inhibition, salivary cortisol, or salivary alpha-amylase. However, there was a trend observed, where the magnitude of the increase in salivary alpha-amylase levels in the exercise condition marginally predicted the improvement in reaction time on the Eriksen flanker task. This suggests that exercise-induced changes in alpha-amylase may underlie improvements in executive function and highlights the need for additional research to more fully understand these relationships in preadolescent children

Aerobic Fitness Markers Associated with Post-Paddling Breath Hold Capacity in Competitive Surfers

International Journal of Exercise Science 12(6): 366-373, 2019. Competitive surfing is a growing sport with evolving performance and safety demands. One particular challenge surfers face is the need to endure long breath-holds following bouts of surf paddling. The purpose of this study was to examine the association between aerobic fitness markers, such as VO2peak and ventilatory thresholds, and post-paddling breath-hold capacity in competitive surfers. Eleven male collegiate level competitive surfers completed both a maximal graded exercise test and a simulated post-paddling breath-hold challenge on a modified paddling ergometer. Associations between markers of aerobic fitness and post-paddling breath-hold capacity were tested using linear regression modeling. The overall regression model indicated a positive linear association between the assessed markers of aerobic fitness and post-paddling breath-hold capacity (r= .828, r2= 0.686, p = 0.035). This association was explained by differences in VO2peak(ß= 0.975, p = .034). These findings suggest that VO2peak may be an important training target for programs aimed at improving breath-hold capacity in surfers

Associations among physical activity, screen time, and sleep in low socioeconomic status urban girls

Insufficient sleep is associated with higher risk of poor health outcomes in low socioeconomic status (SES) urban elementary age girls. Decreased physical activity (PA) and increased screen time may be associated with poor sleep. This study examined if PA and screen time are associated with sleep in girls from a low SES urban community. Baseline data from 7 to 12 year-old girls (n = 55) from two interventions conducted in Springfield, MA between 2012 and 2015 were used. PA was measured via accelerometry for seven days. Screen time and sleep were assessed via validated questionnaires. Sleep was also assessed via accelerometry in a subsample of girls (n = 24) for 7 days. Associations among PA, screen time, and sleep were analyzed using multiple linear regression. More minutes of screen time per day (p = 0.01, r2 = 0.35, r2 adjusted = 0.23) was associated with worse sleep quality (β = 0.50, p = 0.02). There were negative correlations between PA and the number of awakenings per night (r = −0.45, p = 0.04) and between counts per minute and sleep fragmentation (r = −0.65, p = 0.002) assessed by accelerometer. In this population, increased screen time was associated with worse sleep quality and decreased PA was correlated with more awakenings per night and higher sleep fragmentation. These findings suggest that screen time and PA may be modifiable risk factors for interventions seeking to improve sleep in this population