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Jennifer Ryan, Michael Walsh, and John Gormley

This study investigated the ability of published cut points for the RT3 accelerometer to differentiate between levels of physical activity intensity in children with cerebral palsy (CP). Oxygen consumption (metabolic equivalents; METs) and RT3 data (counts/min) were measured during rest and 5 walking trials. METs and corresponding counts/min were classified as sedentary, light physical activity (LPA), and moderate to vigorous physical activity (MVPA) according to MET thresholds. Counts were also classified according to published cut points. A published cut point exhibited an excellent ability to classify sedentary activity (sensitivity = 89.5%, specificity = 100.0%). Classification accuracy decreased when published cut points were used to classify LPA (sensitivity = 88.9%, specificity = 79.6%) and MVPA (sensitivity = 70%, specificity = 95–97%). Derivation of a new cut point improved classification of both LPA and MVPA. Applying published cut points to RT3 accelerometer data collected in children with CP may result in misclassification of LPA and MVPA.

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Ryan Eckert, Jennifer Huberty, Heidi Kosiorek, Shannon Clark-Sienkiewicz, Linda Larkey, and Ruben Mesa

Introduction: The delivery of online interventions in cancer patients/survivors has increased. The measurement of participation in online interventions is important to consider, namely, the challenges of the remote assessment of activity. The purpose of this study was to report the measures used to assess intervention compliance and other physical activity participation in two online yoga studies, the relationship between the multimethod measures used, and the ability of cancer patients to complete these measures. Methods: The methods described are of two online yoga studies (feasibility and pilot). Cancer patients were asked to participate in 60 min/week of online yoga for 12 weeks, complete a weekly yoga log, wear a Fitbit daily for 12 weeks, and complete a weekly physical activity log. Finally, Clicky®, a web analytics software, was used to track online yoga participation. Results: Eighty-four people participated across both studies, with 63/84 participating in online yoga, averaging 57.5 ± 33.2 min/week of self-reported yoga participation compared to 41.4 ± 26.1 min/week of Clicky® yoga participation (Lin concordance = 0.28). All 84 participants averaged 95.5 ± 111.8 min/week of self-reported moderate/vigorous physical activity compared with 98.1 ± 115.9 min/week of Fitbit-determined moderate/vigorous physical activity (Lin concordance = 0.33). Across both studies, 82.9% of the yoga logs were completed, the Fitbit was worn on 75.2% of the days, and 78.7% of the physical activity logs were completed. Conclusions: Weak relationships between self-report and objective measures were demonstrated, but the compliance rates were above 75% for the study measures. Future research is needed, investigating the intricacies of self-report physical activity participation in remote interventions and the validation of a gold standard measurement for online interventions.

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Michelle S. Rockwell, Madlyn I. Frisard, Janet W. Rankin, Jennifer S. Zabinsky, Ryan P. Mcmillan, Wen You, Kevin P. Davy, and Matthew W. Hulver

The purpose of this study was to evaluate the impact of fall season vitamin D3 supplementation on strength/power, body composition, and anabolic hormones in swimmers with optimal vitamin D status at summer’s end. Male and female National Collegiate Athletic Association Division I swimmers (N = 19) with optimal 25-hydroxyvitamin D [25(OH)D] randomly received 5,000 IU of vitamin D3 (VITD) or placebo (PLA) daily for 12 weeks while participating in swimming and strength and conditioning training (August–November). Before and after the intervention, the participants underwent blood sampling for analysis of serum 25(OH)D, parathyroid hormone, total testosterone, free testosterone, sex hormone-binding globulin, and insulin-like growth factor 1, dual-energy X-ray absorptiometry, and strength/power testing (bench press, squat, dead lift, standing broad jump, vertical jump, and dips and pull-ups). Sex was used as a covariate for analyses. The 25(OH)D was decreased by 44% in PLA (p < .05) and increased by 8% in VITD over the 12 weeks. Fat-free mass increased in VITD (56.4–59.1 kg; p < .05), but not PLA (59.4–59.7 kg; p < .01). Significant Group × Time interaction effects were observed for dead lift (F = 21.577, p < .01) and vertical jump (F = 11.219, p < .01), but no other strength/power tests. Total testosterone decreased similarly in both groups, but free testosterone decreased and sex hormone-binding globulin increased only in PLA (p < .01). There were no group differences or changes in insulin-like growth factor 1 with the intervention. The findings suggest that vitamin D supplementation is an efficacious strategy to maintain 25(OH)D during the fall season training and to enhance some aspects of strength/power and fat-free mass in swimmers. Further research on the relationship between vitamin D and anabolic hormones is needed.

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Ryan S. Garten, Matthew C. Scott, Tiffany M. Zúñiga, Austin C. Hogwood, R. Carson Fralin, and Jennifer Weggen

Background: This study sought to determine the impact of an acute prior bout of high-intensity interval aerobic exercise on attenuating the vascular dysfunction associated with a prolonged sedentary bout. Methods: Ten young (24 ± 1 y) healthy males completed two 3-hour sessions of prolonged sitting with (SIT-EX) and without (SIT) a high-intensity interval aerobic exercise session performed immediately prior. Prior to and 3 hours into the sitting bout, leg vascular function was assessed with the passive leg movement technique, and blood samples were obtained from the lower limb to evaluate changes in oxidative stress (malondialdehyde and superoxide dismutase) and inflammation (interleukin-6). Results: No presitting differences in leg vascular function (assessed via passive leg movement technique-induced hyperemia) were revealed between conditions. After 3 hours of prolonged sitting, leg vascular function was significantly reduced in the SIT condition, but unchanged in the SIT-EX. Lower limb blood samples revealed no alterations in oxidative stress, antioxidant capacity, or inflammation in either condition. Conclusions: This study revealed that lower limb vascular dysfunction was significantly attenuated by an acute presitting bout of high-intensity interval aerobic exercise. Further analysis of lower limb blood samples revealed no changes in circulating oxidative stress or inflammation in either condition.

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Myles W. O’Brien, Jennifer L. Petterson, Liam P. Pellerine, Madeline E. Shivgulam, Derek S. Kimmerly, Ryan J. Frayne, Pasan Hettiarachchi, and Peter J. Johansson

Wearable activity monitors provide objective estimates of time in different physical activity intensities. Each continuous stepping period is described by its length and a corresponding single intensity (in metabolic equivalents of task [METs]), creating square wave–shaped signals. We argue that physiological responses do not resemble square waves, with the purpose of this technical report to challenge this idea and use experimental data as a proof of concept and direct potential solutions to better characterize activity intensity. Healthy adults (n = 43, 19♀; 23 ± 5 years) completed 6-min treadmill stages (five walking and five jogging/running) where oxygen consumption (3.5 ml O2·kg−1·min−1 = 1 MET) was recorded throughout and following the cessation of stepping. The time to steady state was ∼1–1.5 min, and time back to baseline following exercise was ∼1–2 min, with faster stepping stages generally exhibiting longer durations. Instead of square waves, the duration intensity signal reflected a trapezoid shape for each stage. The METs per minute during the rise to steady state (upstroke slopes; average: 1.7–6.3 METs/min for slow walking to running) may be used to better characterize activity intensity for shorter activity bouts where steady state is not achieved (within ∼90 s). While treating each activity bout as a single intensity is a much simpler analytical procedure, characterizing each bout in a continuous manner may better reflect the true physiological responses to movement. The information provided herein may be used to improve the characterization of activity intensity, definition of bout breaks, and act as a starting point for researchers and software developers interested in using wearables to measure activity intensity.

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Amal A. Wanigatunga, Fangyu Liu, Jacek K. Urbanek, Hang Wang, Junrui Di, Vadim Zipunnikov, Yurun Cai, Ryan J. Dougherty, Eleanor M. Simonsick, Luigi Ferrucci, and Jennifer A. Schrack

Wrist-worn accelerometry metrics are not well defined in older adults. Accelerometry data from 720 participants (mean age 70 years, 55% women) were summarized into (a) total activity counts per day, (b) active minutes per day, (c) active bouts per day, and (d) activity fragmentation (the reciprocal of the mean active bout length). Linear regression and mixed-effects models were utilized to estimate associations between age and gait speed with wrist accelerometry. Activity counts per day, daily active minutes per day, and active bouts per day were negatively associated with age among all participants, while positive associations with activity fragmentation were only observed among those ≥65 years. More activity counts, more daily active minutes, and lower activity fragmentation were associated with faster gait speed. There were baseline age interactions with annual changes in total activity counts per day, active minutes per day, and activity fragmentation (Baseline age × Time, p < .01 for all). These results help define and characterize changes in wrist-based physical activity patterns among older adults.