This study examined postural sway in children in eyes open (EO) and eyes closed (EC) conditions, controlling for body mass index (BMI) and physical activity (PA). Sixty two children (aged 8–11years) underwent sway assessment using computerized posturography from which 95% ellipse sway area, anterior/posterior (AP) sway, medial/lateral (ML) sway displacement and sway velocity were assessed. Six trials were performed alternatively in EO and EC. BMI (kg/m2) was determined from height and mass. PA was determined using sealed pedometry. AP amplitude (p = .038), ML amplitude (p = .001), 95% ellipse (p = .0001), and sway velocity (p = .012) were higher in EC compared with EO conditions. BMI and PA were not significant as covariates. None of the sway variables were significantly related to PA. However, sway velocity during EO (p = .0001) and EC (p = .0001) was significantly related to BMI. These results indicate that sway is poorer when vision is removed, that BMI influences sway velocity, but that pedometer-assessed PA was not associated with postural sway.
Michael Duncan, Elizabeth Bryant, Mike Price, Samuel Oxford, Emma Eyre and Mathew Hill
Emma L. J. Eyre, Jason Tallis, Susie Wilson, Lee Wilde, Liam Akhurst, Rildo Wanderleys and Michael J. Duncan
Background: The ability to objectively assess physical activity and inactivity in free living individuals is important in understanding activity patterns and the dose response relationship with health. Currently, a large number of research tools exist, but little evidence has examined the validity/utility of the Research Tracker 6 (RT6) monitor. Questions remain in regard to the best placements, positions, and cut-points in young adults to determine activity intensity across a range of activities. This study sought to address this gap in young adults. The study aims were 1) to examine criterion validity of RT6 in comparison to breath-by-breath gas analysis; 2) convergent validity of RT6 in comparison to ActiGraph and GENEActiv; 3) development of RT6 tri-axial vector magnitude cut-points to classify physical activity at different intensities (i.e., for sedentary, moderate, and vigorous); 4) to compare the generated cut-points of the RT6 in comparison to other tools. Methods: Following ethics approval and informed consent, 31 young adults (age = 22±3 years: BMI = 23±3 kg/m2) undertook five modes of physical activity/sedentary behaviors while wearing three different accelerometers at hip and wrist locations (ActiGraph GT9X Link, GENEActiv, RT6). Expired gas was sampled during the five activities (MetaMax 3B). Correlational analysis assessed the relationship between accelerometer devices and METs/VO2. Receiver Operating Characteristic Curves analysis were used to calculate area under the curve and define cut-points for physical activity intensities. Results: The RT6 demonstrated criterion and convergent validity (r = 0.662–0.966, P < .05). RT6 generally performed good to excellent across activity intensities and monitor position (sedentary [AUC = 0.862–0.911], moderate [AUC = 0.849–0.830], vigorous [AUC = 0.872–0.877]) for non-dominant and dominant position, respectively. Cut-points were derived across activity intensities for non-dominant- and dominant-worn RT6 devices. Comparison of the RT6 derived cut-points identified appropriate agreement with comparative tools but yields the strongest agreement with the ActiGraph monitor at the hip location during sedentary, light, and moderate activity. Conclusion: The RT6 performed similar to the ActiGraph and GENEActiv and is capable of classifying the intensity of physical activity in young adults. As such this may offer a more useable tool for understanding current physical activity levels and in intervention studies to monitor and track changes without the excessive need for downloading and making complex analysis, especially given the option to view energy expenditure data while wearing it. The RT6 should be placed on the dominant hip when determining activities that are sedentary, moderate, or vigorous intensity.
Mark R. Noon, Emma L.J. Eyre, Matthew Ellis, Tony D. Myers, Rhys O. Morris, Peter D. Mundy, Ryan Penny and Neil D. Clarke
Purpose: To investigate the influence of recruitment age on retention and release across the development pathway and to explore the influence of anthropometric and physical characteristics on retention and release at different ages throughout the development pathway and the likelihood of obtaining a professional contract. Methods: Following receipt of ethics approval, a cross-sectional study tracking 4 cohorts of players over 5 years assessed 76 male youth football players (11–16 y) from an English football academy on 3 occasions annually in anthropometry, countermovement jump height, and linear (30 and 15 m) and multidirectional sprint time. Players were categorized based on their start and release date. Results: Starting early (ie, before U12) in an academy was a key indicator of obtaining a professional contract, representing 87% of the players signed. Bayesian regression models suggest that the majority of differences in physical characteristics between players that were released and retained are trivial, small, and/or uncertain. Players who attained a professional contract at 18 had slower 15- and 30-m sprint times at U13 to U15 (P > 0 = .87–.99), slower multidirectional sprint times at U14 (P > 0 = .99), and lower countermovement jump height at U13 to U16 (P > 0 = .88–.99) compared with players who did not gain a contract. Conclusion: Players recruited early have an increased likelihood of gaining a professional contract. Physical assessments lack utility when used in isolation as a talent-identification tool.