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Mark L. Latash

Motor control is a young and aspiring field of natural science. Over the past 40 years, it has become an established field of study with several important theoretical developments, including the equilibrium-point hypothesis and its more recent version known as the control with referent spatial coordinates, the principle of abundance, the uncontrolled manifold hypothesis, and the concept of dynamic neural field as the means of task formulation. Important experimental advances have included the exploration of the notion of synergies, the links between descending signals from the brain and referent coordinates of the effectors, and applications of motor control principles to analysis of disordered movements. Further maturation of motor control requires focusing on theory-driven studies. It promises fruitful applications to applied fields such as movement disorders and rehabilitation.

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Sarah K. Keadle, Eduardo E. Bustamante, and Matthew P. Buman

Over the past 40 years, physical activity (PA) and public health has been established as a field of study. A robust evidence base has emerged demonstrating that participation in recommended amounts of PA results in a wide array of physical and mental health benefits. This led to the establishment of federal and global PA guidelines and surveillance programs. Strong evidence supports the efficacy of individual-level (e.g., goal setting) and environmental (e.g., policies) interventions to promote PA. There has also been progress in establishing a skilled and diverse workforce to execute the work of PA and public health. Looking forward, major challenges include stemming the obesity and chronic disease epidemics, addressing health inequities, and diversifying the workforce. Given the known benefits of PA and the availability of evidence-based interventions, efforts now must focus on implementing this knowledge to improve population health and reduce inequities through PA.

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Eric T. Hyde, John D. Omura, Tiffany J. Chen, David R. Brown, Janet E. Fulton, and Susan A. Carlson

The Physical Activity Guidelines for Americans, second edition recommends that older adults do multicomponent physical activity, which includes balance training in addition to aerobic and muscle-strengthening activities. The authors estimated the prevalence of U.S. older adults (age ≥65 years) who do balance activities and meet the aerobic and muscle-strengthening physical activity guidelines. The authors analyzed data on 1,012 respondents to the 2019 FallStyles survey, a nationwide web-based panel survey. Approximately four in 10 respondents (40.7%) reported doing balance activities on ≥1 day/week, 34.0% on ≥2 days/week, and 25.3% on ≥3 days/week. Prevalence differed by sex, education level, income level, census region, body mass index category, and meeting the aerobic and/or muscle-strengthening guidelines. The combined prevalence of participation in balance activities and meeting aerobic and muscle-strengthening guidelines ranged from 12.0% for ≥3 days/week to 15.8% for ≥1 day/week. Opportunities exist to introduce and increase participation in balance and multicomponent activities by older adults.

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Sam McCormack, Ben Jones, Sean Scantlebury, Neil Collins, Cameron Owen, and Kevin Till

Purpose: To compare the physical qualities between academy and international youth rugby league (RL) players using principal component analysis. Methods: Six hundred fifty-four males (age = 16.7 [1.4] y; height = 178.4 [13.3] cm; body mass = 82.2 [14.5] kg) from 11 English RL academies participated in this study. Participants completed anthropometric, power (countermovement jump), strength (isometric midthigh pull; IMTP), speed (10 and 40 m speed), and aerobic endurance (prone Yo-Yo IR1) assessments. Principal component analysis was conducted on all physical quality measures. A 1-way analysis of variance with effect sizes was performed on 2 principal components (PCs) to identify differences between academy and international backs, forwards, and pivots at under 16 and 18 age groups. Results: Physical quality measures were reduced to 2 PCs explaining 69.4% of variance. The first PC (35.3%) was influenced by maximum and 10-m momentum, absolute IMTP, and body mass. Ten and forty-meter speed, body mass and fat, prone Yo-Yo, IMTP relative, maximum speed, and countermovement jump contributed to PC2 (34.1%). Significant differences (P < .05, effect size = −1.83) were identified between U18 academy and international backs within PC1. Conclusion: Running momentum, absolute IMTP, and body mass contributed to PC1, while numerous qualities influenced PC2. The physical qualities of academy and international youth RL players are similar, excluding U18 backs. Principal component analysis can reduce the dimensionality of a data set and help identify overall differences between playing levels. Findings suggest that RL practitioners should measure multiple physical qualities when assessing physical performance.

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Oğuz K. Esentürk and Erkan Yarımkaya

The aim of this study was to evaluate the feasibility and potential efficacy of a WhatsApp-based physical activity for children with autism spectrum disorder (ASD). Fourteen parents and their children with ASD participated in the study. The intervention included parents conducting physical activities with their children with ASD for 4 weeks. Physical activity contents were provided to parents via the WhatsApp group. The data were collected through the Leisure Time Exercise Questionnaire and a feasibility questionnaire adapted from previous studies examining the feasibility of web-based physical activities. Parents reported that WhatsApp-based physical activities were a feasible intervention to increase the physical activity level of their children with ASD and stated that the contents of the physical activity shared in the WhatsApp group were useful. The findings provided preliminary evidence for the use of WhatsApp-based physical activities to increase the physical activity level of children with ASD who stay at home due to the pandemic.

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Liam Collins and J. Paige Pope

Older adults spend more time, on average, engaged in sedentary behaviors (SBs) compared with younger cohorts. This is concerning, because prolonged SB is associated with detrimental outcomes. The purpose of this study was to explore the degree to which older adults’ motives to limit their SB were internalized, consistent with self-determination theory. Following the qualitative description approach, seven focus groups (n = 27) of community-dwelling older adults were conducted. Focus groups were transcribed verbatim and coded using a thematic approach. Results revealed some motivation subthemes, which appeared to endorse similar content, varied in the degree to which participants internalized them, differentiating these motives along the self-determination theory motivational continuum. These findings demonstrated that not all motives are equal, highlighting the importance of theory-driven future SB interventions.

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Floor A.P. van den Brandt, Inge K. Stoter, Ruby T.A. Otter, and Marije T. Elferink-Gemser

Purpose: In long-track speed skating, drafting is a commonly used phenomenon in training; however, it is not allowed in time-trial races. In speed skating, limited research is available on the physical and psychological impact of drafting. The aim of this study was to determine the influence of “skating alone,” “leading,” or “drafting” on physical intensity (heart rate and blood lactate) and perceived intensity (perceived exertion) of speed skaters. Methods: Twenty-two national-level long-track speed skaters with a mean age of 19.3 (2.6) years skated 5 laps, with similar external intensity in 3 different conditions: skating alone, leading, or drafting. Repeated-measures analysis of variance showed differences between the 3 conditions, heart rate (F 2,36 = 10.546, P < .001), lactate (F 2,36 = 12.711, P < .001), and rating of perceived exertion (F 2,36 = 5.759, P < .01). Results: Heart rate and lactate concentration were significantly lower (P < .001) when drafting compared with leading (heart rate Δ = 7 [8] beats·min–1, 4.0% [4.7%]; lactate Δ = 2.3 [2.3] mmol/L, 28.2% [29.9%]) or skating alone (heart rate Δ = 8 [7.1] beats·min–1, 4.6% [3.9%]; lactate Δ = 2.8 [2.5] mmol/L, 33.6% [23.6%]). Rating of perceived exertion was significantly lower (P < .01) when drafting (Δ = 0.8 [1.0], 16.5% [20.9%]) or leading (Δ = 0.5 [0.9], 7.7% [20.5%]) versus skating alone. Conclusions: With similar external intensity, physical intensity, as well as perceived intensity, is reduced when drafting in comparison with skating alone. A key finding of this study is the psychological effect: Skating alone was shown to be more demanding than leading, whereas leading and drafting were perceived to be similar in terms of perceived exertion. Knowledge about the reduction of internal intensity for a drafting skater compared with leading or skating alone can be used by coaches and trainers to optimize training conditions.

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Grace Wei, Jeffrey Farooq, Leslie Castelo-soccio, and Rahul Mhaskar

Background: Physical activity is associated with greater odds of sunburn in adults, increasing harmful sun exposure and skin cancer risk. The authors sought to investigate parallel associations between sunburn and physical activity among US high school students. Methods: The authors examined pooled cross-sectional data from the 2015 and 2017 Youth Risk Behavior Survey. A nationally representative sample of 21,894 US high school students who responded to the sunburn question was included. Results: Prevalence of sunburn was 56.6% between 2015 and 2017. Sunburn prevalence was higher in physically active students (88.3%; 95% confidence interval [CI], 86.7%–90.0%; P < .0001) and student athletes (63.0%; 95% CI, 59.4%–66.7%; P < .0001). Among male students who were vigorously physically active (≥5 d) or on ≥3 teams, the odds of sunburn were 2.33 (95% CI, 1.81–3.00; P < .0001) and 2.52 (95% CI, 1.96–3.23; P < .0001), respectively. Among female students who were vigorously physically active (≥5 d) or on ≥3 teams, the odds of sunburn were 1.65 (95% CI, 1.36–2.02; P < .0001) and 2.92 (95% CI, 2.07–4.13; P < .0001), respectively. Conclusions: Many US high school students are affected by sunburn, and the odds of sunburn are elevated during physical activity and team sports participation. Efforts are needed to improve sun safety regulations, education, and resources for youth during school and physical activity.

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Jonathan P. Davy, Karine Scheuermaier, Laura C. Roden, Candice J. Christie, Alison Bentley, Francesc X. Gomez-Olive, Stella Iacovides, Raphaella Lewis, Gosia Lipinska, Johanna Roche, Andrew Todd, Swantje Zschernack, and Dale E. Rae

Background: The authors assessed the impact of lockdown in response to the COVID-19 pandemic on routine-oriented lifestyle behaviors and symptoms of depression, anxiety, and insomnia in South Africans. Methods: In this observational study, 1048 adults (median age = 27 y; n = 767 females; n = 473 students) responded to an online survey on work, exercise, screen, alcohol, caffeine and sleep behaviors, depression, anxiety, and insomnia before and during lockdown. Comparisons were made between males and females, and students and nonstudents. Results: During lockdown, males reported larger reductions in higher intensity exercise and alcohol use than females, while depressive symptoms increased more among females, more of whom also reported poorer sleep quality. Students demonstrated larger delays in work and sleep timing, greater increases in sitting, screen, sleep duration, napping, depression and insomnia and larger decreases in work hours, exercise time, and sleep regularity compared with nonstudents. Conclusions: Students experienced more changes in their routine-oriented behaviors than nonstudents, coupled with larger increases in depression and insomnia. The dramatic change in their work and sleep timing suggests habitual routines that are at odds with their chronotype, with their sleep changes during lockdown likely reflecting “catch-up” sleep in response to accumulated sleep debt under usual routines.

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Paul Mackie, Gary Crowfoot, Heidi Janssen, Elizabeth Holliday, David Dunstan, and Coralie English

Background: Interrupting prolonged sitting acutely lowers blood pressure in nonstroke populations. However, the dose–response effect in stroke survivors is unknown. The authors investigated different doses of light-intensity standing exercises that interrupt prolonged sitting and reduce blood pressure immediately and over 24 hours in stroke survivors. Methods: Within-participant, laboratory-based, dose escalation trial. Conditions (8 h) were prolonged sitting and 2 experimental conditions of standing exercises with increasing frequency (3 cohorts, 2 × 5 min to 6 × 5 min). The primary outcome is the mean systolic blood pressure. Results: Twenty-nine stroke survivors (aged 66 [12] y) participated. Frequent bouts of standing exercises lowered the mean systolic blood pressure following the 4 × 5-minute (−2.1 mm Hg; 95% confidence interval [CI], −3.6 to −0.6) and 6 × 5-minute conditions (−2.3 mm Hg; 95% CI, −4.2 to −0.5) compared with prolonged sitting. Diastolic blood pressure was lowered following the 6 × 5-minute condition (−1.4 mm Hg; 95% CI, −2.7 to −0.2). The 24-hour systolic blood pressure increased following the 2 × 5-minute condition (6.9 mm Hg; 95% CI, 3.1 to 10.6). Conclusions: Interrupting prolonged sitting with more frequent bouts of standing exercises lowers systolic and diastolic blood pressure in stroke survivors. However, reductions may only be short term, and investigations on sustained effects are warranted.