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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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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.

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Jim Potvin

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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.

Open access

Sathvik Namburar, William Checkley, Oscar Flores-Flores, Karina M. Romero, Katherine Tomaino Fraser, Nadia N. Hansel, Suzanne L. Pollard and GASP Study Investigators

Background: The authors sought to examine physical activity patterns among children with and without asthma in 2 peri-urban communities in Lima, Peru, to identify socioeconomic and demographic risk factors for physical inactivity and examine the relationship between asthma and physical activity. Methods: The authors measured mean steps per day in 114 children (49 with asthma and 65 without) using pedometers worn over a 1-week period. They also used the 3-day physical activity recall to determine the most common activities carried out by children. Results: The authors found that 84.2% of the children did not meet the daily international physical activity recommendations. Girls took significantly fewer mean steps per day as compared with boys (2258 fewer steps, 95% confidence interval, 1042–3474), but no other factors, including asthma status, showed significant differences in the mean daily steps. Mean daily steps were positively associated with higher socioeconomic status among girls, and current asthma had a larger inverse effect on daily steps in boys when compared with girls. Conclusion: Physical activity levels were below recommended guidelines in all children. There is a need for policy and neighborhood-level interventions to address low physical activity levels among Peruvian youth. Special focus should be given to increasing the physical activity levels in girls.

Open access

Robert J. Gregor

Open access

Christopher C. Moore, Aston K. McCullough, Elroy J. Aguiar, Scott W. Ducharme and Catrine Tudor-Locke

Background: The authors conducted a scoping review as a first step toward establishing harmonized (ie, consistent and compatible), empirically based best practices for validating step-counting wearable technologies. Purpose: To catalog studies validating step-counting wearable technologies during treadmill ambulation. Methods: The authors searched PubMed and SPORTDiscus in August 2019 to identify treadmill-based validation studies that employed the criterion of directly observed (including video recorded) steps and cataloged study sample characteristics, protocol details, and analytical procedures. Where reported, speed- and wear location–specific mean absolute percentage error (MAPE) values were tabulated. Weighted median MAPE values were calculated by wear location and a 0.2-m/s speed increment. Results: Seventy-seven eligible studies were identified: most had samples averaging 54% (SD = 5%) female and 27 (5) years of age, treadmill protocols consisting of 3 to 5 bouts at speeds of 0.8 (0.1) to 1.6 (0.2) m/s, and reported measures of bias. Eleven studies provided MAPE values at treadmill speeds of 1.1 to 1.8 m/s; their weighted median MAPE values were 7% to 11% for wrist-worn, 1% to 4% for waist-worn, and ≤1% for thigh-worn devices. Conclusions: Despite divergent study methodologies, the authors identified common practices and summarized MAPE values representing device step-count accuracy during treadmill walking. These initial empirical findings should be further refined to ultimately establish harmonized best practices for validating wearable technologies.