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Danny M. Pincivero, Rachael R. Polen and Brittany N. Byrd

The objective of the present study was to examine the relationship between maximal effort force production and anthropometric measures of upper-arm volume. Thirty healthy young participants (15 women) performed 5 isokinetic concentric and eccentric maximal effort elbow flexor/extensor contractions on separate days. Measures of arm length, circumference, and skinfold/subcutaneous fat thickness were used to obtain a measure of arm volume, modeled as 2 separate right-angle frustra. Single-variable regression analyses demonstrated significant (P < .001) second-order polynomial relationships between maximal effort elbow flexor and extensor force with arm volume (r 2 = .63–.86). The major findings demonstrated that strong and positive relations between maximal force production and estimates of limb volume can be observed using nonlinear modeling and a closer geometric representation of the exercising limb.

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Eduardo L. Caputo, Paulo H. Ferreira, Manuela L. Ferreira, Andréa D. Bertoldi, Marlos R. Domingues, Debra Shirley and Marcelo C. Silva

Background: To investigate whether engagement in leisure-time physical activity before or during pregnancy is associated with low back pain (LBP) outcomes during pregnancy and postpartum prevalence of LBP in women who reported LBP during pregnancy. Methods: Data from the 2015 Pelotas Birth Cohort Study, were used. Demographic, socioeconomic, and gestational characteristics, as well as physical activity prior to and during pregnancy were recorded at perinatal assessment. LBP outcomes during pregnancy (pain intensity, activity limitation, and care seeking) and postpartum (prevalence of LBP) were collected at the 1-year follow-up. Results: Pain intensity, care seeking, and prevalence of LBP postpartum period were not associated with physical activity either before or during pregnancy. However, women engaged in physical activity during pregnancy and at least for 2 trimesters had lower odds ratio of activity limitation associated with LBP during pregnancy (odds ratio: 0.60; 95% confidence interval, 0.41 to 0.88; odds ratio: 0.20; 95% confidence interval, 0.04 to 0.86, respectively). Conclusion: Meeting the recommended levels of physical activity during pregnancy is associated with less activity limitation related to LBP during pregnancy. However, physical activity levels, either before or during pregnancy, were not associated with pain intensity, care seeking, and postpartum LBP.

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Tania Pereira, John Durocher and Jamie Burr

Background: Insufficient physical activity (PA) is associated with numerous chronic diseases and premature mortality, and the challenge of meeting recommended PA guidelines is exacerbated in the winter. Snowmobiling can potentially contribute to PA accumulation, but the objective metabolic and physical demands are unclear. The purpose of this study was to assess the physical demands of riding a snowmobile. Methods: Habitual snowmobile riders responded to a survey describing a typical ride (n = 4015). Using this data, terrain-specific testing courses were created, and recreational snowmobile riders (n = 40) participated in a scaled representative ride (21 [8] min) while aerobic metabolism (VO2) and muscular fatigue were quantified. Results: The mean VO2 while riding, irrespective of terrain, was 18.5 (8.4) mL·kg−1·min−1, with significant differences based on geographic location (13.4 [5.2] vs 25.7 [6.6] mL·kg−1·min−1, P < .001). Muscular fatigue was apparent in maximal handgrip (−7% [8%], P < .001) across both riding terrains, but not lower body power, suggesting a greater influence of an upper body strength component. Conclusions: Snowmobiling is an activity that generally falls within the moderate-intensity activity range and involves both aerobic fitness and muscular strength. There were substantial differences in demand between terrains, suggesting that additional benefits may be conferred from mountain riding as it was more metabolically demanding.

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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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Julie D. Guldager, Anja Leppin, Jesper von Seelen and Pernille T. Andersen

Background: The reasons for the mixed evidence of the effectiveness of school-based physical activity programs can be many, including implementation challenges. Studying program implementation can potentially contribute to enhancing effectiveness, the design of future interventions, improved implementation, and the interpretation of outcomes. Methods: For this process evaluation, individual interviews were conducted with 16 teachers who had implemented the program “Active All Year Round” in a fifth-grade school class (students aged 9–11 y) in 2017. Through systematic text condensation feasibility and barriers of program implementation, perceived program reach and the programs’ influence on social cohesion were identified and discussed. Results: Teachers described the program as very feasible to implement and identified very few implementation barriers, the most prominent being time constrains. Perceived program reach was very high, and teachers reported that those students who are less confident when it comes to physical activity did not have differential participation than those feeling more confident about physical activity. Finally, the program was perceived to positively affect social cohesion in class. Conclusions: Active All Year Round is a standardized, flexible, and easily implemented program in Danish schools. Future studies are needed to study implementation from a student’s perspective and/or students’ role in and experiences with competition-based health programs.

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Xihe Zhu and Justin A. Haegele

The purpose of this study was to examine reactivity to accelerometer measurement in children with visual impairments (VI), their sighted siblings, and their parents. A sample of 66 participants (including 22 children with VI, 22 siblings, and 22 parents) completed a demographic survey and wore triaxial accelerometers for at least 4 consecutive days for 8 hr. An analysis of covariances with repeated measures was conducted, controlling for participant gender. Children with VI had 8.1% less moderate to vigorous physical activity time on Day 1 than Days 2–4 average. Their sighted siblings and parents had 7.8% and 7.1% more moderate to vigorous physical activity time on Day 1 than their Days 2–4 average, respectively. The reactivity percentage for parents and children without VI is consistent with existing literature. However, an inverse reactivity for children with VI was found, which is a unique contribution to the literature and will have implications for researchers using accelerometers for this population.

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Kevin Deschamps, Giovanni Matricali, Maarten Eerdekens, Sander Wuite, Alberto Leardini and Filip Staes

Foot structure and kinematics have long been considered as risk factors for foot and lower-limb running injuries. The authors aimed at investigating foot joint kinetics to unravel their receptive and propulsive characteristics while running barefoot, both with rearfoot and with midfoot striking strategies. Power absorption and generation occurring at different joints of the foot in 6 asymptomatic adults were calculated using both a 3-segment and a 4-segment kinetic model. An inverse dynamic approach was used to quantify mechanical power. Major power absorption and generation characteristics were observed at the ankle joint complex as well as at the Chopart joint in both the rearfoot and the midfoot striking strategies. The power at the Lisfranc joint, quantified by the 4-segment kinetic model, was predominantly generated in both strategies, and at the toes, it was absorbed. The overall results show a large variability in the receptive and propulsive characteristics among the analyzed joints in both striking strategies. The present study may provide novel insight for clinical decision making to address foot and lower-limb injuries and to guide athletes in the adoption of different striking strategies during running.

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Wesley J. Wilson and K. Andrew R. Richards

Occupational socialization theory has been used to understand the recruitment, education, and socialization of physical education teachers for nearly 40 yr. It has, however, only recently been applied to the study of adapted physical education teachers. The purpose of this descriptive case study was to understand the socialization of preservice teachers in an adapted physical education teacher education graduate-level program. Participants included 17 purposefully selected preservice teachers (5 male and 12 female) enrolled in a yearlong graduate-level adapted physical education teacher education program. Qualitative data were collected using interviews, reflective journaling, and field notes taken during teaching and coursework observations. Data analysis resulted in the construction of 3 themes: overcoming contextual challenges to meet learners’ needs, the importance of field-based teacher education, and coping with the challenges of marginalization. The discussion connects to and advances occupational socialization theory in adapted physical education and suggests that professional socialization may have a more profound influence on preservice adapted physical education teachers than on their physical education counterparts.

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Chelsea L. Kracht, Elizabeth K. Webster and Amanda E. Staiano

Background: Little is known about variation in meeting the 24-Hour Movement Guidelines (including physical activity [PA], sleep, and screen time [ST]) in early childhood. The aim was to evaluate sociodemographic differences in meeting the 24-Hour Movement Guidelines. Methods: Parents of 3–4 year old children reported sociodemographic information and ST. Sleep and PA were measured using accelerometry, and height and weight were objectively measured. The 24-Hour Movement Guidelines include daily PA (total PA: ≥3 h; including ≥1 h of moderate to vigorous), sleep (10–13 h), and ST (≤1 h). Meeting guidelines by age, sex, race, poverty level, and weight status were assessed using chi-square and linear regression models. Results: Of 107 children, 57% were white and 26% lived in households at or below the poverty level. Most children met the PA (91.5%) and sleep (86.9%) guidelines, but few met ST (14.0%) or all 3 (11.3%) guidelines. African American children and children who lived at or below the poverty level were less likely to meet the sleep, ST, and all 3 guidelines compared with others (P < .01 for all). There were no other differences. Conclusion: These results suggest future interventions should focus on reducing differences in movement, namely in sleep and ST.

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Ana F. Silva, Pedro Figueiredo, Sara Morais, João P. Vilas-Boas, Ricardo J. Fernandes and Ludovic Seifert

This study aimed to examine young swimmers’ behavioral flexibility when facing different task constraints, such as swimming speed and stroke frequency. Eighteen (five boys and 13 girls) 13- to 15-year-old swimmers performed a 15 × 50-m front crawl with five trials, at 100%, 90%, and 70% each of their 50 m maximal swimming speed and randomly at 90%, 95%, 100%, 105%, and 110% of their preferred stroke frequency. Seven aerial and six underwater cameras were used to assess kinematics (one cycle), with upper-limb coordination computed through a continuous relative phase and index of coordination. A cluster analysis identified six patterns of coordination used by swimmers when facing various speed and stroke frequency constraints. The patterns’ nature and the way the swimmers shifted between them are more important than getting the highest number of patterns (range of repertoire), that is, a change in the motor pattern in order to adapt correctly is more important than being able to execute a great number of patterns.