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Adam Grainger, Paul Comfort and Shane Heffernan

Purpose: Partial body cryotherapy (PBC) has been shown to be beneficial for postexercise recovery; however, no study has demonstrated the effectiveness of PBC for recovery following elite rugby union training. Rugby union is a unique sport that involves high-velocity collisions and may induce greater performance decrements than other sports; thus, PBC could be beneficial. The application of PBC in “real world” has rarely been investigated during the competitive phase of a playing season and warranted investigation. Methods: In a counterbalanced sequential research design, professional rugby athletes (n = 18; age 25.4 [4.0] y; training age 7.2 [4.0] y; mass 99.8 [10.6] kg; height 188.3 [6.0] cm) were assigned to a 12-week PBC intervention, washout period (4 wk), and reassessed as their own controls. Self-reported well-being, muscle soreness, sleep quality, and countermovement jump height were assessed before and 40 hours after “real-world” training. Wilcoxon signed-rank tests and Cohen d were used for statistical analysis. Results: No differences were observed between PBC and control conditions (P > .05; d = 0.00–0.14) for well-being (−0.02% [0.08%] vs 0.01% [0.06%]), muscle soreness (−0.01% [0.11%] vs 0.01% [0.16%]), sleep quality (−0.03% [0.14%] vs 0.10% [0.29%]), or countermovement jump height (36.48–36.59 vs 38.13–37.52 cm; P = .54). Conclusions: These results suggest PBC is ineffective for the restoration of selected performance parameters during the performance maintenance phase of the competitive season. To ascertain the appropriation of its use, future investigations should seek to assess the use of cryotherapies at various phases of the elite rugby union competitive season.

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Nathan Hall, Brent Bradford, José da Costa and Daniel B. Robinson

Background and Purpose: Despite widespread evidence suggesting the numerous benefits from being active in outdoor environments, children in many Western nations have recently been spending less time outdoors. This cross-sectional exploratory study provides a descriptive examination of physical education teachers’ embracement of alternative environment activities (AEAs) in physical education programs. Method: Data were collected from 225 current physical education teachers in Alberta and Manitoba, Canada, through an online survey. Data were analyzed using descriptive statistics, factor analysis, Levene’s tests, and independent t tests. Results: Significant differences were found in relation to teachers’ experiences, or lack thereof, with professional development in relation to the extent to which teachers embraced AEAs. Furthermore, cost was discovered to be the greatest perceived barrier to teaching AEAs. Discussion and Conclusions: This study reveals an established need for teachers’ professional development in teaching AEAs and for discovering ways to decrease cost barriers for teaching AEAs.

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Paddy C. Dempsey, Chuck E. Matthews, S. Ghazaleh Dashti, Aiden R. Doherty, Audrey Bergouignan, Eline H. van Roekel, David W. Dunstan, Nicholas J. Wareham, Thomas E. Yates, Katrien Wijndaele and Brigid M. Lynch

Background: Recent updates to physical activity guidelines highlight the importance of reducing sedentary time. However, at present, only general recommendations are possible (ie, “Sit less, move more”). There remains a need to investigate the strength, temporality, specificity, and dose–response nature of sedentary behavior associations with chronic disease, along with potential underlying mechanisms. Methods: Stemming from a recent research workshop organized by the Sedentary Behavior Council themed “Sedentary behaviour mechanisms—biological and behavioural pathways linking sitting to adverse health outcomes,” this paper (1) discusses existing challenges and scientific discussions within this advancing area of science, (2) highlights and discusses emerging areas of interest, and (3) points to potential future directions. Results: A brief knowledge update is provided, reflecting upon current and evolving thinking/discussions, and the rapid accumulation of new evidence linking sedentary behavior to chronic disease. Research “action points” are made at the end of each section—spanning from measurement systems and analytic methods, genetic epidemiology, causal mediation, and experimental studies to biological and behavioral determinants and mechanisms. Conclusion: A better understanding of whether and how sedentary behavior is causally related to chronic disease will allow for more meaningful conclusions in the future and assist in refining clinical and public health policies/recommendations.

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Erin Calaine Inglis, Danilo Iannetta, Daniel A. Keir and Juan M. Murias

Purpose: To evaluate whether the coherence in the oxygen uptake (V˙O2) associated with the respiratory compensation point (RCP), near-infrared spectroscopy-derived muscle deoxyhemoglobin ([HHb]) break point ([HHb]BP), and maximal lactate steady state (MLSS) would persist at the midpoint and endpoint of a 7-month training and racing season. Methods: Eight amateur male cyclists were tested in 3 separate phases over the course of a cycling season (PRE, MID, and POST). Testing at each phase included a ramp-incremental test to exhaustion to determine RCP and [HHb]BP. The PRE and POST phases also included constant power output rides to determine MLSS. Results: Compared with PRE, V˙O2 at both RCP and [HHb]BP was greater at MID (delta: RCP 0.23 [0.14] L·min−1, [HHb]BP 0.33 [0.17] L·min−1) and POST (delta: RCP 0.21 [0.12], [HHb]BP 0.30 [0.14] L·min−1) (P < .05). V˙O2 at MLSS also increased from PRE to POST (delta: 0.17 [12] L·min−1) (P < .05). V˙O2 was not different at RCP, [HHb]BP, and MLSS at PRE (3.74 [0.34], 3.64 [0.40], 3.78 [0.23] L·min−1) or POST (3.96 [0.25], 3.95 [0.32], 3.94 [0.18] L·min−1) respectively, and RCP (3.98 [0.33] L·min−1) and [HHb]BP (3.97 [0.34] L·min−1) were not different at MID (P > .05). PRE–MID and PRE–POST changes in V˙O2 associated with RCP, [HHb]BP, and MLSS were strongly correlated (range: r = .85–.90) and demonstrated low mean bias (range = −.09 to .12 L·min−1). Conclusions: At all measured time points, V˙O2 at RCP, [HHb]BP, and MLSS were not different. Irrespective of phase comparison, direction, or magnitude of V˙O2 changes, intraindividual changes between each index were strongly related, indicating that interindividual differences were reflected in the group mean response and that their interrelationships are beyond coincidental.

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Thomas P. Oates

This article examines the articulation of the Black ghetto to authenticity through the involvement of hip hop star Jay-Z in two highly publicized basketball-related ventures during 2003. During that year, Jay-Z organized a team for the Entertainer’s Basketball Classic (EBC) in Harlem’s Rucker Park and joined a team of investors aiming to move the New Jersey Nets to a new arena in Brooklyn. Informed by cultural studies scholarship, the paper explains the context through which basketball and hip hop were articulated with authenticity, and were deployed towards the goal of managing a career transition for Jay-Z, and was also used to gain public support for a controversial proposal to build an arena in the Atlantic Yards area of Brooklyn.

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Anson B. Rosenfeldt, Amanda L. Penko, Andrew S. Bazyk, Matthew C. Streicher, Tanujit Dey and Jay L. Alberts

The aim of this project was to (a) evaluate the potential of the 2-min walk test to detect declines in gait velocity under dual-task conditions and (b) compare gait velocity overground and on a self-paced treadmill in Parkinson’s disease (PD). In total, 23 individuals with PD completed the 2-min walk test under single- and dual-task (serial 7s) conditions overground and on a self-paced treadmill. There was a significant decrease in gait velocity from single- to dual-task conditions overground (1.32 ± 0.22 to 1.10 ± 0.25 m/s; p < .001) and on the self-paced treadmill (1.24 ± 0.21 to 1.05 ± 0.25 m/s; p < .001). Overground and treadmill velocities were not statistically different from each other; however, differences approached or exceeded the minimal clinical important difference. The 2-min walk test coupled with a cognitive task provides an effective model of identifying dual-task declines in individuals with PD. Further studies comparing overground and self-paced treadmill velocity is warranted in PD.

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Aisha Chen, Sandhya Selvaraj, Vennila Krishnan and Shadnaz Asgari

Accurate and reliable detection of the onset of gait initiation is essential for the correct assessment of gait. Thus, this study was aimed at evaluation of the reliability and accuracy of 3 different center of pressure–based gait onset detection algorithms: A displacement baseline–based algorithm (method 1), a velocity baseline–based algorithm (method 2), and a velocity extrema–based algorithm (method 3). The center of pressure signal was obtained during 10 gait initiation trials from 16 healthy participants and 3 participants with Parkinson’s disease. Intrasession and absolute reliability of each algorithm was assessed using the intraclass correlation coefficient and the coefficient of variation of center of pressure displacement during the postural phase of gait initiation. The accuracy was evaluated using the time error of the detected onset by each algorithm relative to that of visual inspection. The authors’ results revealed that although all 3 algorithms had high to very high intrasession reliabilities in both healthy subjects and subjects with Parkinson’s disease, methods 2 and 3 showed significantly better absolute reliability than method 1 in healthy controls (P = .001). Furthermore, method 2 outperformed the other 2 algorithms in both healthy subjects and subjects with Parkinson’s disease with an overall accuracy of 0.80. Based on these results, the authors recommend using method 2 for accurate and reliable gait onset detection.

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Joshua Twaites, Richard Everson, Joss Langford and Melvyn Hillsdon

Purpose: Physical activity classifiers are typically trained on data obtained from sensors at a set orientation. Changes in this orientation (such as being on a different wrist) result in performance degradation. This work investigates a method to obtain sensor location and orientation invariance for classification of wrist-mounted accelerometry via a technique known as domain adaption. Methods: Data was gathered from 16 participants who wore accelerometers on both wrists. Physical activity classification models were created using data from each wrist and then used to predict activities when using data from the opposing wrist. Using subspace alignment domain adaption, this procedure was then repeated to align the training and testing data before the classification stage. Results: Prediction of activity when using data where the wearer’s wrist was incorrectly specified resulted in a significant (p = .01) decrease in performance of 12%. When using domain adaption this drop in performance became negligible (M difference < 1%, p = .73). Conclusion: Domain adaption is a valuable method for achieving accurate physical activity classification independent of sensor orientation in wrist-worn accelerometry.

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Katja Krustrup Pedersen, Esben Lykke Skovgaard, Ryan Larsen, Mikkel Stengaard, Søren Sørensen and Kristian Overgaard

Accelerometers are widely used to measure physical activity, but limitations in the ability to differentiate between running intensities have been reported. This problem may relate to accelerometer placement. In this study, we compare the validity of accelerometers placed on the hip and the thigh for the measurement of walking and running speed under laboratory and field conditions. Young healthy men and women wore ActiGraph GT3X+ accelerometers on the hip and on the thigh while performing walking and running activities in laboratory (n = 31) and field conditions (n = 17). Vector magnitude counts per minute (VM cpm) were correlated with speed of locomotion and, during laboratory trials, with oxygen consumption (VO2, ml·min−1·kg−1). Both hip- and thigh-placed VM cpm showed strong correlations with walking speed ranging from 3 to 7 km·h−1 (r = 0.93 and r = 0.95, respectively) and VO2 (r = 0.85 and r = 0.91, respectively). Compared with the hip-placed VM cpm, thigh-placed VM cpm showed significantly stronger correlations with running speed ranging from 7 to 20 km·h−1 (r = 0.29 and r = 0.89, respectively) and the corresponding VO2 (r = 0.25 and r = 0.87, respectively). Regardless of accelerometer placement, VM cpm were similar between laboratory and field tests performed at comparable walking and running speeds. These results show that accelerometers placed on the thigh, but not on the hip, provide proportional output across a wide range of walking and running speeds. Thus, thigh-placed accelerometers are able to differentiate between running intensities in both laboratory and field conditions.

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Jonathan M. Miller, Mark A. Pereira, Julian Wolfson, Melissa N. Laska, Toben F. Nelson and Dianne Neumark-Sztainer

Background: This study tested for differences in personal, social, and environmental correlates of moderate to vigorous physical activity (MVPA) across ethnicity/race in male and female adolescents. Methods: Self-reported MVPA and 47 potential correlates of MVPA were measured in an ethnically/racially diverse cross-sectional sample of adolescents, in Minnesota, who participated in EAT-2010 (Eating and Activity in Teens). Interactions of potential correlates with ethnicity/race on MVPA were tested in linear hierarchical regression models in boys and girls. Results: Boys reported 1.7 more weekly hours of MVPA than girls. White adolescents reported 1.1 to 2.1 more weekly hours of MVPA than nonwhite adolescents. Among girls, neighborhood road connectivity was negatively correlated with MVPA among Hispanic and Asian participants. Among boys, sports participation was positively correlated with MVPA among all ethnicities/races, except Asians. Home media equipment was positively correlated with MVPA among Hispanic boys, but negatively correlated among white boys. Conclusions: A few correlates of physical activity among adolescents differed intersectionally by ethnicity/race and sex. Sports participation and home media equipment may have differing impacts on physical activity across ethnicities and races in boys, whereas neighborhood features like road connectivity may have differing impacts on physical activity across ethnicities and races in girls.