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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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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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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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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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Karl M. Newell

A review and synthesis of the literature on the learning and development of motor skills supports the postulation that whether a motor skill can be deemed fundamental is dependent on the collective presence of three conditions: (i) uniqueness to the movement pattern and/or outcome; (ii) near universality of the functional outcome in the healthy population; (iii) capacity to act as an antecedent influence supporting generalization to a large and broad set of perceptual-motor skills. Within this framework, it is proposed that the infant motor development sequence underpinning upright posture (e.g., sitting, bipedal standing), locomotion (e.g., walking, running), and object-interaction (e.g., grasping) represents the minimum set of fundamental motor skills from which all other skills evolve with over the lifespan. This position is in contrast to the views of many students of motor development and learning who describe numerous skills that typically emerge in the ∼2- to 18-year-old range as fundamental but do not meet the criteria outlined here to be fundamental. It is proposed that these be labeled as core developmental activities having a more restricted but still practically relevant influence on the acquisition of and generalization to other motor skills.

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Damiano Formenti, Luca Cavaggioni, Marco Duca, Athos Trecroci, Mattia Rapelli, Giampietro Alberti, John Komar and Pierpaolo Iodice

Background: Recent evidence has suggested that chronic physical activities including balance exercises have positive effects on cognition, but their acute effects are still unknown. In the present study, the authors tested the hypothesis that an acute bout of balance exercise would enhance cognitive performance compared with aerobic activity. Methods: A total of 20 healthy middle-aged adults completed 2 acute 30-minute balance and moderate-intensity aerobic exercise sessions on 2 counterbalanced separate occasions. To assess cognitive functions, performance tasks in executive control, perceptual speed, and simple reaction time were tested before and immediately after each exercise session. Results: Although there were no significant interactions (time × exercise condition, P > .05), the main effects of time were significant in executive control (P < .05), perceptual speed (P < .05), and simple reaction time (P < .001), showing improvements after both exercises. Conclusions: These findings highlight that both types of exercise (aerobic, more metabolic and less cognitively demanding; balance, more cognitively and less metabolically demanding) were able to positively affect simple reaction time performance, perceptual speed, and executive control independently of physiological adjustments occurring during aerobic or balance exercise.

Open access

Andy J. King, Joshua T. Rowe and Louise M. Burke

The benefits of ingesting exogenous carbohydrate (CHO) during prolonged exercise performance are well established. A recent food technology innovation has seen sodium alginate and pectin included in solutions of multiple transportable CHO, to encapsulate them at pH levels found in the stomach. Marketing claims include enhanced gastric emptying and delivery of CHO to the muscle with less gastrointestinal distress, leading to better sports performance. Emerging literature around such claims was identified by searching electronic databases; inclusion criteria were randomized controlled trials investigating metabolic and/or exercise performance parameters during endurance exercise >1 hr, with CHO hydrogels versus traditional CHO fluids and/or noncaloric hydrogels. Limitations associated with the heterogeneity of exercise protocols and control comparisons are noted. To date, improvements in exercise performance/capacity have not been clearly demonstrated with ingestion of CHO hydrogels above traditional CHO fluids. Studies utilizing isotopic tracers demonstrate similar rates of exogenous CHO oxidation, and subjective ratings of gastrointestinal distress do not appear to be different. Overall, data do not support any metabolic or performance advantages to exogenous CHO delivery in hydrogel form over traditional CHO preparations; although, one study demonstrates a possible glycogen sparing effect. The authors note that the current literature has largely failed to investigate the conditions under which maximal CHO availability is needed; high-performance athletes undertaking prolonged events at high relative and absolute exercise intensities. Although investigations are needed to better target the testimonials provided about CHO hydrogels, current evidence suggests that they are similar in outcome and a benefit to traditional CHO sources.

Open access

Erin Kraft, Diane M. Culver and Cari Din

The following practice paper introduces an innovative women-only training program for coach developers in a Canadian provincial sport organization. The dearth of women in coaching and sport leadership positions informs the program as a whole and the participant perspectives on what is working, in practice, for them specifically in a way that could support future sport leaders interested in increasing gender equity in their sport organizations and leadership skills in their female leaders. The aims of the coach developer program are two-fold: to promote women in leadership and to create a social learning space for women to connect and support each other in their leadership development. The purpose of this practice paper is to discuss the supports that have enabled the facilitation of this program and to explore the value of a women-only training program. Two women (out of a total of 10) participating in the program and two leads facilitating the program were interviewed for their perspectives. The lessons learned touch on the types of value that were created (immediate, potential, and applied) and the specific supports (micro, meso, and macro) that enabled the facilitation of the program. Finally, the authors discuss additional considerations (e.g., consistent buy-in from the organization is needed) with practical insights in the hopes of inspiring other sport organizations to implement similar initiatives for promoting women in leadership and coaching in sport.

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Nicolas Aguilar-Farias, Sebastian Miranda-Marquez, Pia Martino-Fuentealba, Kabir P. Sadarangani, Damian Chandia-Poblete, Camila Mella-Garcia, Jaime Carcamo-Oyarzun, Carlos Cristi-Montero, Fernando Rodriguez-Rodriguez, Pedro Delgado-Floody, Astrid Von Oetinger, Teresa Balboa-Castillo, Sebastian Peña, Cristobal Cuadrado, Paula Bedregal, Carlos Celis-Morales, Antonio Garcia-Hermoso and Andrea Cortínez-O’Ryan

Background: The study summarizes the findings of the 2018 Chilean Report Card (RC) on Physical Activity (PA) for Children and Adolescents and compares the results with the first Chilean RC and with other countries from the Global Matrix 3.0. Methods: A Research Work Group using a standardized methodology from the Global Matrix 3.0 awarded grades for 13 PA-related indicators based on the percentage of compliance for defined benchmarks. Different public data sets, government reports, and papers informed the indicators. Results: The grades assigned were for (1) “behaviors that contribute to overall PA levels”: overall PA, D−; organized sport participation, D−; active play, INC; and active transportation, F; (2) “factors associated with cardiometabolic risk”: sedentary behavior, C−; overweight and obesity, F; fitness, D; sleep, INC; and (3) “factors that influence PA”: family and peers, F; school, D; inclusion, INC; community and built environment, B; government strategies and investments, B−. Conclusions: Chile’s grades remained low compared with the first RC. On the positive side, Chile is advancing in environmental and policy aspects. Our findings indicate that the implementation of new strategies should be developed through collaboration between different sectors to maximize effective investments for increasing PA and decreasing sedentary time among children and adolescents in Chile.

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Sarah A. Roelker, Elena J. Caruthers, Rachel K. Hall, Nicholas C. Pelz, Ajit M.W. Chaudhari and Robert A. Siston

Two optimization techniques, static optimization (SO) and computed muscle control (CMC), are often used in OpenSim to estimate the muscle activations and forces responsible for movement. Although differences between SO and CMC muscle function have been reported, the accuracy of each technique and the combined effect of optimization and model choice on simulated muscle function is unclear. The purpose of this study was to quantitatively compare the SO and CMC estimates of muscle activations and forces during gait with the experimental data in the Gait2392 and Full Body Running models. In OpenSim (version 3.1), muscle function during gait was estimated using SO and CMC in 6 subjects in each model and validated against experimental muscle activations and joint torques. Experimental and simulated activation agreement was sensitive to optimization technique for the soleus and tibialis anterior. Knee extension torque error was greater with CMC than SO. Muscle forces, activations, and co-contraction indices tended to be higher with CMC and more sensitive to model choice. CMC’s inclusion of passive muscle forces, muscle activation-contraction dynamics, and a proportional-derivative controller to track kinematics contributes to these differences. Model and optimization technique choices should be validated using experimental activations collected simultaneously with the data used to generate the simulation.