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Yvonne G. Ellis, Dylan P. Cliff, Steven J. Howard and Anthony D. Okely

Purpose: To examine the acute effects of a reduced sitting day on executive function (EF) and musculoskeletal health in preschoolers. Methods: A sample of 29 children (54% boys; 4–5 y) participated in a randomized cross-over trial. Each child completed 2 protocols, which simulate a day at childcare in random order for 2.5 hours; a typical preschool day (50% sitting) and a reduced preschool day (25% sitting) where most sitting activities were replaced with standing activities. Sitting, standing, and stepping time were objectively assessed using an activPAL accelerometer. EF was evaluated using tablet-based EF assessments (inhibition, working memory, and task shifting). Musculoskeletal health was assessed using a handheld dynamometer and goniometer. Results: Compared with the typical preschool day, the reduced sitting day showed no significant differences for EF scores. Effect sizes for inhibition (d = 0.04), working memory (d = 0.02), and shifting (d = 0.11) were all small. For musculoskeletal health, no significant differences were reported after the reduced preschool day. The effect sizes for the hip extension force, hamstring flexibility, gastrocnemius length, and balancing on 1 leg were all small (d = 0.21, d = 0.25, d = 0.28, and d = 0.28). Conclusions: This study suggests that reducing sitting time is unlikely to result in acute changes in EF and musculoskeletal health among preschoolers.

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Sanaz Nosrat, James W. Whitworth, Nicholas J. SantaBarbara, Shira I. Dunsiger and Joseph T. Ciccolo

Depressive symptoms and fatigue are prevalent among people living with human immunodeficiency virus. Resistance exercise is known to stimulate a positive affective response. Objective: To examine the acute psychological effects of resistance-exercise intensity among Black/African-American people living with human immunodeficiency virus and experiencing depressive symptoms. Methods: A total of 42 participants were randomized into a moderate- (n = 21) or high-intensity (n = 21) group. Assessments were collected before exercise (PRE), at the midpoint (MID), immediately following (POST) exercise, and 15 (DELAY 15) and 30 (DELAY 30) min after. Results: In the moderate-intensity group, affect improved PRE to POST, PRE to DELAY 15 and DELAY 30, and perceived distress decreased from PRE to all time points. In the high-intensity group, affect declined PRE to MID, and perceived distress decreased PRE to DELAY 15 and DELAY 30. Perceived activation increased PRE to MID, and POST in both groups (ps < .01). Conclusions: The moderate-intensity group compared with the high-intensity group is more effective at improving affect and energy and at reducing distress.

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Mohammad Siahpush, Trish D. Levan, Minh N. Nguyen, Brandon L. Grimm, Athena K. Ramos, Tzeyu L. Michaud and Patrik L. Johansson

Background: The mortality benefits of meeting the US federal guidelines for physical activity, which includes recommendations for both aerobic and muscle-strengthening activities, have never been examined among smokers. Our aim was to investigate the association between reporting to meet the guidelines and all-cause, cancer, cardiovascular disease, and respiratory disease mortality among smokers. Methods: We pooled data from the 1998–2009 National Health Interview Survey, which were linked to records in the National Death Index (n = 68,706). Hazard ratios (HR) were computed to estimate the effect of meeting the physical activity guidelines on mortality. Results: Smokers who reported meeting the guidelines for physical activity had 29% lower risk of all-cause mortality (HR: 0.71; 95% confidence interval [CI], 0.62–0.81), 46% lower risk of mortality from cardiovascular disease (HR: 0.54; 95% CI, 0.39–0.76), and 26% lower risk of mortality from cancer (HR: 0.74; 95% CI, 0.59–0.93), compared with those who reported meeting neither the aerobic nor the muscle-strengthening recommendations of the guidelines. Meeting the aerobic recommendation of the guidelines was associated with a 42% decline in that risk (HR: 0.58; 95% CI, 0.44–0.77). Conclusion: Smokers who adhere to physical activity guidelines show a significant reduction in mortality.

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Astrid C.J. Balemans, Han Houdijk, Gilbert R. Koelewijn, Marjolein Piek, Frank Tubbing, Anne Visser-Meily and Olaf Verschuren

Background: It is questionable whether postures that are regarded as sedentary behavior in able-bodied persons evoke comparable physiological responses in adults with stroke or cerebral palsy (CP). This study aimed to compare metabolic demand and muscle activity in healthy controls, adults with stroke, and adults with CP during sedentary behavior and light physical activities. Methods: Seventy-one adults (45.6 [18.9] y, range 18–86) participated in this study, of which there were 18 controls, 31 with stroke, and 22 with CP. The metabolic equivalent of task (MET) and level of muscle activation were assessed for different sedentary positions (sitting supported and unsupported) and light physical activities (standing and walking). Results: During sitting supported and unsupported, people with mild to moderate stroke and CP show comparable MET and electromyographic values as controls. While sitting unsupported, people with severe stroke show higher METs and electromyographic values (P < .001), and people with severe CP only show higher METs compared with controls (P < .05) but all below 1.5 METs. Standing increased electromyographic values in people with severe stroke or CP (P < .001) and reached values above 1.5 METs. Conclusions: Physiologic responses during sedentary behavior are comparable for controls and adults with mild to moderate stroke and CP, whereas higher metabolic demands and muscle activity (stroke only) were observed in severely affected individuals.

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Cui Zhang, Qipeng Song, Wei Sun and Yu Liu

Daily stair activities have become increasingly challenging for older adults with deterioration in physical and cognitive capabilities. However, the dynamic stability of older adults during stair descent under a concurrent dual-task condition remains undetermined. The gait and dynamic stability variables of 40 healthy older adults were measured under single- and dual-task conditions during stair descent. The step length, step width, and single support time did not significantly increase (p > .05) under the dual-task condition during stair descent. The medial–lateral center of mass velocity significantly increased (p < .003), whereas the medial–lateral margin of dynamic stability value significantly decreased (p < .006) at the landing and initial single support under the dual-task condition during stair descent. The self-regulatory ability of healthy older adults under the dual-task condition during stair descent was underestimated. Dual tasking displayed a positive impact on the anterior–posterior dynamic stability of healthy older adults.

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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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Julián Gandía, Xavier García-Massó, Adrián Marco-Ahulló and Isaac Estevan

Feedback is one of the most influential factors for motor skills learning. Physical Education teachers commonly use verbal cues to provide knowledge of process (KP) when teaching motor skills, but the ideal presentation frequency for KP in adolescents is unclear. The aim of this study was to compare the effectiveness of the frequency of KP (i.e., 100%, 67%, 0%) on dynamic balance. Thirty adolescents, age 14–15 years, participated in the study. Performance on a stabilometer platform was used to assess dynamic balance. Participants received feedback after each trial (100%), in two out of three trials (67%), or no feedback during 12 30-s trials of practice. Adolescents who received feedback (67% or 100%) required lower mean velocity to maintain similar dynamic balance performance (i.e., root mean square). Moreover, adolescents receiving 100% feedback had a higher α-scaling than those who did not received it. During the post-test and the retention, both 67% and 100% KP frequencies were effective at improving postural control, compared to the no feedback control.