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M. Spencer Cain, Kyeongtak Song, J. Troy Blackburn, Kimmery Migel and Erik A. Wikstrom

Ankle joint mobilization has been shown to be effective at improving outcomes in those with chronic ankle instability (CAI), but the neuromuscular mechanisms are still unknown. We aimed to determine the immediate effect of a single Grade III anterior-to-posterior ankle joint mobilization bout on ankle musculotendinous stiffness (MTS) in those with CAI. Seventeen CAI participants had plantar flexor and fibularis MTS assessed before and after a 5-min joint mobilization treatment. MTS outcomes were estimated using the damped oscillation method. Fibularis (0.25 ± 0.41 N/m/kg, p = .028) but not plantar flexor MTS (−2.18 ± 14.35 N/m/kg, p = .539) changed following mobilization and exceeded the calculated minimal detectable change score (0.12 N/m/kg). Increased fibularis MTS may represent a neuromuscular mechanism by which ankle joint mobilizations improve postural control in those with CAI.

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William Boyer, James Churilla, Amy Miller, Trevor Gillum and Marshare Penny

Background: The effects of aerobic physical activity (PA) and muscular strengthening activity (MSA) on all-cause mortality risk need further exploration among ethnically diverse populations. Purpose: To examine potential effect modification of race-ethnicity on meeting the PA guidelines and on all-cause mortality. Methods: The study sample (N = 14,384) included adults (20–79 y of age) from the 1999–2006 National Health and Nutrition Examination Survey. PA was categorized into 6 categories based on the 2018 PA guidelines: category 1 (inactive), category 2 (insufficient PA and no MSA), category 3 (active and no MSA), category 4 (no PA and sufficient MSA), category 5 (insufficient PA and sufficient MSA), and category 6 (meeting both recommendations). Race-ethnic groups examined included non-Hispanic white, non-Hispanic black, and Mexican American. Cox-proportional hazard models were used. Results: Significant risk reductions were found for categories 2, 3, and 6 for non-Hispanic white and non-Hispanic black. Among Mexican American, significant risk reductions were found in category 6. Conclusion: In support of the 2018 PA guidelines, meeting both the aerobic PA and MSA guidelines significantly reduced risk for all-cause mortality independent of race-ethnicity. The effects of aerobic PA alone seem to be isolated to non-Hispanic white and non-Hispanic black.

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Ainaz Shamshiri, Iman Rezaei, Ehsan Sinaei, Saeed Heidari and Ali Ghanbari

Context: The Balance Error Scoring System (BESS), originally designed to diagnose and assess athletes with concussion syndrome, is now widely used to evaluate postural stability. To interpret balance status, a normative database can be a reliable source. However, different anthropometric characteristics and sociocultural backgrounds across populations hinder the application of previously developed databases in different populations. Objective: The present study was designed to develop a normative data set for the general population of healthy Iranian adults according to their age groups and to study the correlation between BESS scores and the participants’ sex, height, weight, and body mass index. Design: A cross-sectional study. Participants: A total of 1051 community-dwelling adults aged 20–69 years not suffering from balance disorders, dizziness, or other neurological or musculoskeletal diseases were recruited and stratified into 5 different age groups by decade. Main Outcome Measures: The BESS tests were composed of single-leg, double-leg, and tandem stances, each on a rigid surface and a foam pad. The individuals maintained each position for 20 seconds with eyes closed. The assessor recorded the total number of errors as the individuals’ BESS score (range: 0–60). Results: Significant but weak correlations were found between BESS score and height (r = −.13, P < .001) and between BESS score and body mass index (r = .11, P < .001), and the difference between sexes in BESS score was statistically significant in the 50- to 59-year-old (P = .021) and 60- to 69-year-old (P < .001) groups. The BESS scores were significantly different between all age groups (P < .05), except between the 20- to 29-year-old and 30- to 39-year-old groups (P = 1.000) and between the 40- to 49-year-old and 50- to 59-year-old groups (P = .086). Conclusions: This study provided a normative database for different age groups of asymptomatic Iranian adults. The BESS score had weak correlations with height and body mass index and no correlation with weight, and significant differences were found between sexes in 50- to 69-year-old individuals. This study emphasizes the importance of obtaining specific normative data for different populations.

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Ruth P. Saunders, Rod K. Dishman, Marsha Dowda and Russell R. Pate

Background: Interventions promoting physical activity (PA) in youth have had limited success, in part because studies with methodological challenges have yielded an incomplete understanding of personal, social, and environmental influences on PA. This study described changes in these factors for subgroups of youth with initially high PA that decreased (Active-Decline) compared with children with initially low PA that decreased (Inactive-Decline) from fifth to ninth grades. Methods: Observational, prospective cohort design. Participants (n = 625) were fifth-grade children recruited in 2 school districts and followed from elementary to high school. Students and their parents responded to questionnaires to assess personal, social, and perceived physical environmental factors in the fifth (mean age = 10.5 [.5] y) and ninth (mean age = 14.7 [.6] y) grades. Analyses included a mixed-model 2-way repeated analysis of variances. Results: Children in the Active-Decline compared with those in the Inactive-Decline group showed a more favorable profile in 6 of 8 personal variables (perceived barriers, self-efficacy, self-schema, enjoyment, competence, and fitness motives) and 4 of 6 social variables (friend support, parent encouragement, parent support, and parent-reported support). Conclusions: The results suggest efforts to promote PA should target selected personal, social, and perceived environmental factors beginning before age 10 and continuing through adolescence.

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Jessica G. Hunter, Alexander M.B. Smith, Lena M. Sciarratta, Stephen Suydam, Jae Kun Shim and Ross H. Miller

Studies of running mechanics often use a standardized lab shoe, ostensibly to reduce variance between subjects; however, this may induce unnatural running mechanics. The purpose of this study was to compare the step rate, vertical average loading rate, and ground contact time when running in standardized lab shoes versus participants’ normal running shoes. Ground reaction forces were measured while the participants ran overground in both shoe conditions at a self-selected speed. The Student’s t-test revealed that the vertical average loading rate magnitude was smaller in lab shoes versus normal shoes (42.09 [11.08] vs 47.35 [10.81] body weight/s, P = .013), while the step rate (170.92 [9.43] vs 168.98 [9.63] steps/min, P = .053) and ground contact time were similar (253 [25] vs 251 [20] ms, P = .5227) and the variance of all outcomes was similar in lab shoes versus normal shoes. Our results indicate that using standardized lab shoes during testing may underestimate the loads runners actually experience during their typical mileage.

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Kathleen S. Wilson and Kevin S. Spink

Purpose: The use of self-efficacy to predict physical activity has a long history. However, this relationship is complex, as self-efficacy is thought to influence and be influenced by physical activity. The directionality of the self-regulatory efficacy (SRE) and physical activity relationship was examined using a cross-lagged design. A secondary purpose was to examine these relationships across differing weather conditions. Methods: Canadian adolescents (N = 337; aged between 13 and 18 years) completed the physical activity and SRE measures 4 times during a school year. Structural equation modeling was used to perform a cross-lag analysis. Results: The relationships between physical activity and SRE appeared to be weather dependent. During a more challenging weather period (eg, cold weather), the relationship between physical activity and SRE was bidirectional. However, no relationship emerged when the 2 constructs were assessed during a more optimal weather period (eg, warm weather). Conclusions: Some support has been provided for the bidirectional nature of the relationship between physical activity and SRE. The relationship appeared to be qualified by climate considerations, suggesting that future research examine how weather may relate not just to physical activity but also to the correlates of physical activity.

Open access

Benjamin J. Narang, Greg Atkinson, Javier T. Gonzalez and James A. Betts

The analysis of time series data is common in nutrition and metabolism research for quantifying the physiological responses to various stimuli. The reduction of many data from a time series into a summary statistic(s) can help quantify and communicate the overall response in a more straightforward way and in line with a specific hypothesis. Nevertheless, many summary statistics have been selected by various researchers, and some approaches are still complex. The time-intensive nature of such calculations can be a burden for especially large data sets and may, therefore, introduce computational errors, which are difficult to recognize and correct. In this short commentary, the authors introduce a newly developed tool that automates many of the processes commonly used by researchers for discrete time series analysis, with particular emphasis on how the tool may be implemented within nutrition and exercise science research.

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Blair Crewther, Christian Cook, John Fitzgerald, Michal Starczewski, Michal Gorski and Joanna Orysiak

Purpose: Reported associations between vitamin 25(OH)D and exercise performance are equivocal, perhaps due to complex interplay with cortisol and testosterone. In this study, the authors investigated serum 25(OH)D and cortisol as moderators of the testosterone relationship with exercise performance in adolescent male athletes. Methods: A total of 88 ice hockey players were assessed for serum 25(OH)D, cortisol, testosterone, body composition, and exercise performance, based on countermovement jump power and muscle torque. The authors tested independent relationships, before examining complex interactions via moderated regression analyses. Results: Most athletes (62.5%) exhibited a suboptimal (20–30 ng·mL−1) serum 25(OH)D concentration, whereas 9.1% of athletes were deficient (<20 ng·mL−1). Serum 25(OH)D was not related to performance when controlling for testing year, age, and fat mass. Further modeling revealed a significant hormonal interaction. Specifically, in low-25(OH)D subjects, testosterone predicted countermovement jump power at a high (β = 7.10, effect size = .43, P < .01), but not low (β = −3.32, effect size = −.20, P = .09), cortisol concentration. Conclusions: Serum 25(OH)D was a poor predictor of exercise performance, but it did moderate (with cortisol) the testosterone link to muscle power. Notably, this relationship emerged among individuals with a 25(OH)D concentration (∼22 ng·mL−1) approaching the deficiency cutoff. Viewing 25(OH)D as a moderating, rather than dose responsive, variable could help explain equivocal cross-sectional associations.

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Daniel H. Aslan, Joshua M. Collette and Justus D. Ortega

The decline of walking performance is a key determinant of morbidity among older adults. Healthy older adults have been shown to have a 15–20% lower walking economy compared with young adults. However, older adults who run for exercise have a higher walking economy compared with older adults who walk for exercise. Yet, it remains unclear if other aerobic exercises yield similar improvements on walking economy. The purpose of this study was to determine if regular bicycling exercise affects walking economy in older adults. We measured metabolic rate while 33 older adult “bicyclists” or “walkers” and 16 young adults walked on a level treadmill at four speeds between (0.75–1.75 m/s). Across the range of speeds, older bicyclists had a 9–17% greater walking economy compared with older walkers (p = .009). In conclusion, bicycling exercise mitigates the age-related deterioration of walking economy, whereas walking for exercise has a minimal effect on improving walking economy.

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Brian Catania, Travis Ross, Bradley Sandella, Bradley Bley and Andrea DiTrani Lobacz

Context: Training and assessment of the abdominal and trunk muscles are widely used in the clinical setting. However, it is unknown what types of exercises are most effective in activation of both the global and local stabilizers in these regions. Objective: The purpose of this study was to establish the reliability of a novel clinical screening tool (sling screen) to assess the muscles of the abdomen and trunk. The second aim was to use the clinical screening tool and musculoskeletal ultrasound to compare the effects of a rotary-based exercise program that targets both the global and local muscles to the effects of a traditional exercise program on the activation of the abdominal and trunk muscles. Design: Double-blind, randomized controlled trial. Setting: Sports medicine facility. Participants and Interventions: Thirty-one healthy participants were randomly allocated to receive a single-session rotary-based or traditional “core” exercise program. Main Outcome Measures: The participants were assessed at the baseline and immediately postintervention. The primary outcome measures were muscle thickness examined by musculoskeletal ultrasound and clinical examination of muscle activation using a screening tool. The data were collected by blind assessors. Reliability and validity of a clinical screening tool (sling screen) were also assessed. Results: The analysis of the covariance tests showed a significant increase in oblique thickness for the rotary exercise group. All participants displayed a significant increase in multifidus thickness. The Wilcoxon signed-rank tests revealed a significant increase in clinical assessment scores in the rotary exercise group but not the traditional exercise group. Reliability of the sling screen ranged from moderate to good. Conclusion: This clinical trial provides evidence that a rotary-based exercise program may be more effective in producing increases in oblique muscle thickness than traditional “core” exercises in young, healthy adults. The sling screen tool was able to identify these muscle thickness changes. Future studies should investigate how these results correlate to injury risk, other populations, and also how to implement the sling screen into clinical practice.