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Open access

Kerstin Bach, Atle Kongsvold, Hilde Bårdstu, Ellen Marie Bardal, Håkon S. Kjærnli, Sverre Herland, Aleksej Logacjov, and Paul Jarle Mork

Introduction: Accelerometer-based measurements of physical activity types are commonly used to replace self-reports. To advance the field, it is desirable that such measurements allow accurate detection of key daily physical activity types. This study aimed to evaluate the performance of a machine learning classifier for detecting sitting, standing, lying, walking, running, and cycling based on a dual versus single accelerometer setups during free-living. Methods: Twenty-two adults (mean age [SD, range] 38.7 [14.4, 25–68] years) were wearing two Axivity AX3 accelerometers positioned on the low back and thigh along with a GoPro camera positioned on the chest to record lower body movements during free-living. The labeled videos were used as ground truth for training an eXtreme Gradient Boosting classifier using window lengths of 1, 3, and 5 s. Performance of the classifier was evaluated using leave-one-out cross-validation. Results: Total recording time was ∼38 hr. Based on 5-s windowing, the overall accuracy was 96% for the dual accelerometer setup and 93% and 84% for the single thigh and back accelerometer setups, respectively. The decreased accuracy for the single accelerometer setup was due to a poor precision in detecting lying based on the thigh accelerometer recording (77%) and standing based on the back accelerometer recording (64%). Conclusion: Key daily physical activity types can be accurately detected during free-living based on dual accelerometer recording, using an eXtreme Gradient Boosting classifier. The overall accuracy decreases marginally when predictions are based on single thigh accelerometer recording, but detection of lying is poor.

Open access

Alanna Weisberg, Hyun Suk Lee, Tak Fung, and Larry Katz

The overhand throw is a complex whole-body motor skill that is fundamental to many sports and activities. When throwing properly, the momentum generated to complete the movement begins in the lower body and transfers through the trunk to the throwing arm. This proof-of-concept study’s primary purpose was to evaluate the impact of the nonthrowing arm on the ball speed during an overhand throw with both the dominant and nondominant arms. Eighteen participants (age: 20.20 ± 2.90 years, nine women) were divided into two intervention groups: a pulling group taught to engage the nonthrowing arm through a pull toward the body and a nonpulling group taught the overhand throw using a component-based physical education curriculum. Each participant completed 12 total throws, six for each side (dominant and nondominant arm). Ball speed and kinematic data were collected using an eight-camera motion analysis system and were assessed using a pre–post study design. The two groups showed significant improvements pre–post when throwing with both the dominant and nondominant arms. Based on effect size comparisons, engaging the nonthrowing arm makes a meaningful difference in maximal ball velocity.

Open access

Bradley J. Cardinal

Kinesiology is a field focused on physical activity and its impact on health, society, and quality of life. But do all people have equal opportunities to access and experience physical activity? Do physical activity settings allow people to freely express themselves? Are the benefits of physical activity universally shared by all people? If the answer to any of these questions is “no,” then these questions demand not only our immediate attention, but also our collective action. During the National Academy of Kinesiology’s 90th anniversary meeting, September 22–24, 2021, these questions and others were explored through presentations devoted to the theme “Kinesiology’s Social Justice Imperative.” This essay overviews the meeting, its purpose, and the organizers and introduces the 11 thematic papers in the “Proceedings of the National Academy of Kinesiology’s 2021 Meeting: Kinesiology’s Social Justice Imperative” issue, plus a 12th essay commemorating the National Academy of Kinesiology’s 90th anniversary meeting.

Open access

Wojtek Chodzko-Zajko, Debra J. Rose, Diane E. Whaley, Philip D. Chilibeck, and Samuel R. Nyman

Open access

Areekul Amornsriwatanakul, Narongsak Noosorn, Kittipong Poonchob, Rung Wongwat, Somkiat Sornprasit, Phataraphon Markmee, Michael Rosenberg, and Karen Milton

Background: This study aimed to determine current practice in physical activity (PA) promotion in Thai schools, explore barriers and facilitators to PA promotion within the school setting, and identify strategies to support schools’ future practice. Methods: A qualitative study design was applied comprising document analysis, focus groups, in-depth interviews, and onsite observations. The focus groups and in-depth interviews were conducted with 144 informants, purposively recruited through 24 schools in 4 regions across Thailand. Inductive content analysis was used. Results: Most schools were promoting PA in the absence of written policies, and without an accurate understanding of PA. Nonalignment of school performance indicators and policies, concerns about children’s academic performance, and lack of budget were raised as barriers to PA promotion, whereas strong partnerships with multiple local stakeholders facilitated school-based PA promotion. Mandated government PA policies and more information support were suggested as strategies to enhance schools’ future practices. Conclusions: For PA promotion to be successful in the school setting, significant challenges will need to be addressed. Results from this study help the government and concerned stakeholders to better understand the situation at the school level, and further strive for achieving the target PA levels specified in the National PA Plan.

Full access

Konstantinos D. Tambalis, Stamatis Mourtakos, and Labros S. Sidossis

Background: The purpose was to examine the potential associations of birth weight and infant growth with physical fitness (PF) components in childhood. Method: A random sample of 5125 dyads of children aged 8–9 years and their mothers were evaluated. Telephone interviews were carried out with the use of a standardized questionnaire for the collection of maternal lifestyle factors. Mothers were asked to provide information contained in their medical booklets and pregnancy ultrasound records. Data from 5 PF tests were used to assess cardiorespiratory fitness, speed, and body strength. Linear regression analysis was applied to assess the associations between birth weight and infant growth with PF test performances and logistic regression analysis to evaluate the associations of normal weight versus low birth weight and normal versus accelerated infant growth with PF tests performance categories (low vs high/average). Results: Birth weight was favorably associated with cardiorespiratory fitness (b = 0.12 stage increase per SD increase in birth weight, P = .047), lower body strength (b = 1.07, P = .037), upper body strength (b = 0.10, P = .038), and speed (b = −0.04, P = .001), and infant growth was associated with upper body strength (b = 0.21 cm increase per SD increase in infant weight gain, P < .001) after adjusting for children’s body mass index and several perinatal factors. Low birth weight children had 35% increased odds for low performances in PF tests compared with their normal birth weight counterparts. Conclusion: Low birth weight negatively affects childhood PF, and hence, it could play an unfavorable role in the future health of the offspring.

Open access

Catherine E. Draper, Takana M. Silubonde, Gudani Mukoma, and Esther M.F. van Sluijs

Background: South Africa launched 24-hour movement guidelines for birth to 5 years in 2018. Perceptions of these guidelines were assessed as part of the dissemination process with community-based organizations in 2019. Methods: Fifteen dissemination workshops were held with community-based organization representatives and a range of stakeholders. Discussions were held with workshop attendees (n = 281) to obtain qualitative feedback on the guidelines and workshop. Six follow-up focus groups (n = 28) were conducted to obtain additional feedback on the guidelines and their dissemination. Discussions and focus groups were thematically analyzed. Results: Participants recognized the importance of the guidelines for the health and development of young South African children. Participants’ perceptions of the guidelines were consistently positive. The participants acknowledged the alignment of the guidelines with other South African programs and initiatives, and that they addressed gaps. Screen time and sleep were identified as the behaviors needing particular attention among young South African children. The negative impact of COVID-19 on young children’s movement behaviors was acknowledged, especially regarding screen time. Conclusion: These findings provide evidence of stakeholders’ positive perceptions of the South African guidelines and support the dissemination and implementation of these guidelines for the promotion of early childhood health and development in South Africa.

Full access

Nathan P. Dawkins, Tom Yates, Cameron Razieh, Charlotte L. Edwardson, Ben Maylor, Francesco Zaccardi, Kamlesh Khunti, and Alex V. Rowlands

Background: Physical activity and sleep are important for health; whether device-measured physical activity and sleep differ by ethnicity is unclear. This study aimed to compare physical activity and sleep/rest in white, South Asian (SA), and black adults by age. Methods: Physical activity and sleep/rest quality were assessed using accelerometer data from UK Biobank. Linear regressions, stratified by sex, were used to analyze differences in activity and sleep/rest. An ethnicity × age group interaction term was used to assess whether ethnic differences were consistent across age groups. Results: Data from 95,914 participants, aged 45–79 years, were included. Overall activity was 7% higher in black, and 5% lower in SA individuals compared with white individuals. Minority ethnic groups had poorer sleep/rest quality. Lower physical activity and poorer sleep quality occurred at a later age in black and SA adults (>65 y), than white adults (>55 y). Conclusions: While black adults are more active, and SA adults less active, than white adults, the age-related reduction appears to be delayed in black and SA adults. Sleep/rest quality is poorer in black and SA adults than in white adults. Understanding ethnic differences in physical activity and rest differ may provide insight into chronic conditions with differing prevalence across ethnicities.

Open access

Kihan Kim, Hojun Sung, Yeayoung Noh, and Kimoon Lee

This study investigated the determinants of television viewership and its relation to broadcasters’ choices of matches for live telecasts. Also, factors driving the broadcasters’ choices were examined. A panel data set from the 2018 Korea Baseball Organization league pennant race was analyzed. Broadcasters’ choice order of matches and the actual television ratings of each match were regressed on a series of antecedent factors related to the game characteristics and audience preferences. It was found that the broadcasters’ choice order of matches positively affected the television ratings, suggesting that the broadcasters’ decisions were well reflected in the actual viewership. It also appeared that broadcasters’ choices were based on popularity and team performance/quality, whereas viewers showed preference for current games’ on-field performance. There was no evidence of audience preference for games with higher outcome uncertainty, whereas the broadcasters tended to choose games with more certain, rather than uncertain, outcomes. Theoretical and practical implications of the findings were discussed.