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Timo B. van den Bogaard, Jabik-Jan Bastiaans, and Mathijs J. Hofmijster

Purpose: To investigate how resistance training (RT) in a regular training program affects neuromuscular fatigue (NMF) and gross efficiency (EGROSS) in elite rowers. Methods: Twenty-six elite male rowers performed 4 RT sessions within 10 days. At baseline and after the first and fourth RT, EGROSS and NMF were established. From breathing gas, EGROSS was determined during submaximal rowing tests. Using a countermovement jump test, NMF was assessed by jump height, flight time, flight-to-contraction-time ratio, peak power, and time to peak power. Muscle soreness was assessed using a 10-cm-long visual analog scale. Results: No significant differences were found for EGROSS (P = .565, ω 2 = .032). Muscle soreness (P = .00, ω 2 = .500) and time to peak power (P = .08, ω2 = 0.238) were higher compared with baseline at all test moments. Flight-to-contraction-time ratio, jump height, and peak power after the fourth RT differed from baseline (P < .05, ω 2 = .36, ω 2 = .38, and ω 2 = .31) and from results obtained after the first RT (P < .05, ω 2 = .36, ω 2 = .47, and ω 2 = .22). Conclusions: RT in general does not influence EGROSS, but large individual differences (4.1%–14.8%) were observed. NMF is affected by RT, particularly after multiple sessions. During periods of intensified RT, imposed external load for low-intensity endurance training need not be altered, but rowers are recommended to abstain from intensive endurance training. Individual monitoring is strongly recommended.

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Kati S. Karinharju, Sjaan R. Gomersall, Kelly M. Clanchy, Stewart G. Trost, Li T. Yeo, and Sean M. Tweedy

This study evaluated the validity of two wheelchair-mounted devices—the Cateye® and Wheeler—for monitoring wheelchair speed and distance traveled. Speed estimates were validated against a calibrated treadmill at speeds from 1.5 to 10 km/hr. Twenty-five wheelchair users completed a course of known distance comprising a sequence of everyday wheelchair activities. Speed estimate validity was very good (mean absolute percentage error ≤ 5%) for the Wheeleri at all speeds and for the Cateye at speeds >3 km/hr but not speeds <3 km/hr (mean absolute percentage error > 20%). Wheeleri distance estimates were good (mean absolute percentage error < 10%) for linear pushing activities and general maneuvering but poor for confined-space maneuvering. Cateye estimates were good for continuous linear propulsion but poor for discontinuous pushing and maneuvering (both general and confined space). Both devices provided valid estimates of speed and distance for typical wheelchair-based exercise activities. However, the Wheeleri provided more accurate estimates of speed and distance during typical everyday wheelchair activities.

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Luciana L.S. Barboza, Larissa Gandarela, Josefa Graziele S. Santana, Ellen Caroline M. Silva, Elondark S. Machado, Roberto Jerônimo S. Silva, Thayse N. Gomes, and Danilo R. Silva

Introduction: The authors’ objective was to identify the minimum number of days required to measure sedentary behavior and physical activity in children during school hours. Methods: Fifty-three children from four classes of the second year of elementary school in a public school in Brazil were selected. Sedentary behavior and physical activity were evaluated using activPAL in the thigh and ActiGraph GT3X on the hip. The devices were used for 4 days during the 4 hr of school. Intraclass correlation coefficient (ICC) and Bland–Altman plots were used for statistical analysis (p < .05). Results: For sedentary/stationary behavior indicators, 1 day showed good agreement with 4 days (sitting time, ICC = .89; bias [limits of agreement 95%, LA95%] = 1.6 [45.1 to −41.9], standing time, ICC = .93; bias [LA95%] 1.1 [30.2 to −28.0], and stationary behavior, ICC = .56; bias [LA95%] = 0.2 [37.2 to −36.7]). However, 2 days were necessary for good agreement, with 4 days for physical activity indicators (walking time, ICC = .91; bias [LA95%] = 1.1 [12.0 to −9.7], light physical activity, ICC = .97; bias [LA95%] = 0.3 [7.6 to −7.0], moderate physical activity, ICC = .93; bias [LA95%] = 0.3 [2.3 to −1.6], and vigorous physical activity, ICC = .93; bias [LA95%] = 0.3 [3.1 to −2.5]). Conclusion: Therefore, 1 evaluation day seems enough to obtain representative data of school sedentary/stationary behavior, while 2 days are necessary for the evaluation of physical activity indicators during school hours.

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Petra Haas, Chih-Hsiang Yang, and Genevieve F. Dunton

Physical activity declines from childhood to adolescence. Affective factors may partially account for this decline. The present study investigated whether within-person changes in children’s enjoyment of physical activity are associated with the age-related decline in physical activity. Children (N = 169, 54% female, 56% Hispanic; 8–12 years old at enrollment) took part in a longitudinal study with six assessment waves across 3 years. At each wave, enjoyment of physical activity was reported, and moderate to vigorous physical activity (MVPA) was measured with an accelerometer across seven consecutive days. MVPA and enjoyment of physical activity both declined across waves. Multilevel analyses revealed that within-person changes in enjoyment moderated the effects of age on within-person changes in MVPA. Enjoyment appeared to be a dynamic factor that buffered against the age-related decline in physical activity in youth. These findings call for health promotion interventions that encourage enjoyable physical activities.

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James W. Roberts, Nicholas Gerber, Caroline J. Wakefield, and Philip J. Simmonds

The failure of perceptual illusions to elicit corresponding biases within movement supports the view of two visual pathways separately contributing to perception and action. However, several alternative findings may contest this overarching framework. The present study aimed to examine the influence of perceptual illusions within the planning and control of aiming. To achieve this, we manipulated and measured the planning/control phases by respectively perturbing the target illusion (relative size-contrast illusion; Ebbinghaus/Titchener circles) following movement onset and detecting the spatiotemporal characteristics of the movement trajectory. The perceptual bias that was indicated by the perceived target size estimates failed to correspondingly manifest within the effective target size. While movement time (specifically, time after peak velocity) was affected by the target configuration, this outcome was not consistent with the direction of the perceptual illusions. These findings advocate an influence of the surrounding contextual information (e.g., annuli) on movement control that is independent of the direction predicted by the illusion.

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Hilary Hicks, Alexandra Laffer, Kayla Meyer, and Amber Watts

As a default setting, many body-worn research-grade activity monitors rely on software algorithms developed for young adults using waist-worn devices. ActiGraph offers the low-frequency extension (LFE) filter, which reduces the movement threshold to capture low acceleration activity, which is more common in older adults. It is unclear how this filter changes activity estimates and whether it is appropriate for all older adults. The authors compared activity estimates with and without the LFE filter on wrist-worn devices in a sample of 34 older adults who wore the ActiGraph GT9X on their nondominant wrist for 7 days in a free-living environment. The authors used participant characteristics to predict discrepancy in step count estimates generated with and without the LFE filter to determine which individuals are most accurately characterized. Estimates of steps per minute were higher (M = 21, SD = 1), and more activity was classified as moderate to vigorous intensity (M = 5.03%, SD = 3.92%) with the LFE filter (M = 11, SD = 1; M = 4.27%, SD = 3.52%) versus without the LFE filter (all ps < .001). The findings suggest that axes-based variables should be interpreted with caution when generated with wrist-worn data, and future studies should develop separate wrist and waist-worn standard estimates in older adults. Participation in a greater amount of moderate to vigorous intensity physical activity predicted a larger discrepancy in step counts generated with and without the filter (p < .009), suggesting that the LFE filter becomes increasingly inappropriate for use in highly active older individuals.

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Shelby Borowski, Jyoti Savla, and Anisa M. Zvonkovic

Background: Little is known about the link between flexible work arrangements and health behaviors, such as physical activity. This study aimed to explore how self-efficacy and daily barriers to physical activity influence daily levels of physical activity on workdays when university staff members used a flexible work arrangement (flextime or telework). Methods: Full-time university staff employees (N = 61, mean age = 41; 89% female) participated in this daily diary study. Participants completed an initial survey followed by daily surveys over the course of one workweek, resulting in 281 diary days. Results: The most frequently reported barriers to physical activity were as follows: lack of time, feeling tired, and not enough motivation. Multilevel models revealed that as the number of barriers increased, minutes of physical activity significantly decreased. Self-efficacy was not significantly related to daily physical activity. Participants reported fewer minutes of physical activity on flextime workdays compared to days when a flexible work arrangement was not used (ie, traditional workday). Daily use of a flexible work arrangement did not moderate the association between barriers and physical activity. Conclusions: This study illustrated the influence of daily barriers and flextime workdays on physical activity levels, which can inform workplace health programs for university staff.

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Matthew Hobbs, Stuart J.H. Biddle, Andrew P. Kingsnorth, Lukas Marek, Melanie Tomintz, Jesse Wiki, John McCarthy, Malcolm Campbell, and Simon Kingham

Background: This study investigates the association between television (TV) viewing and child adiposity and if parental education and child ethnicity moderate this association. Method: Cross-sectional, pooled (2013/2014–2016/2017) adult and child New Zealand Health Survey were matched resulting in 13,039 children (2–14 y) and parent dyads. Child TV viewing was estimated using self-reported time for each weekday and weekend. The height (in centimeters), weight (in kilograms), and waist circumference of parents and children were measured. Childhood body mass index and obesity were defined using the International Obesity Task Force cutoff values. Effect modification was assessed by interaction and then by stratifying regression analyses by parent education (low, moderate, and high) and child ethnicity (Asian, European/other, Māori, and Pacific). Results: Overall, watching ≥2 hours TV on average per day in the past week, relative to <2 hours TV viewing, was associated with a higher odds of obesity (adjusted odds ratio = 1.291 [1.108–1.538]), higher body mass index z score (b = 0.123 [0.061–0.187]), and higher waist circumference (b = 0.546 [0.001–1.092]). Interactions considering this association by child ethnicity and parent education revealed little evidence of effect modification. Conclusion: While TV viewing was associated with child adiposity, the authors found little support for a moderating role of parental education and child ethnicity.