To reduce head impact exposure (HIE) in youth football, further understanding of the context in which head impacts occur and the associated biomechanics is needed. The objective of this study was to evaluate the effect of contact characteristics on HIE during player versus player contact scenarios in youth football. Head impact data and time-synchronized video were collected from 4 youth football games over 2 seasons in which opposing teams were instrumented with the Head Impact Telemetry (HIT) System. Coded contact characteristics included the player’s role in the contact, player speed and body position, contact height, type, and direction, and head contact surface. Head accelerations were compared among the contact characteristics using mixed-effects models. Among 72 instrumented athletes, 446 contact scenarios (n = 557 impacts) with visible opposing instrumented players were identified. When at least one player had a recorded impact, players who were struck tended to have higher rotational acceleration than players in striking positions. When both players had a recorded impact, lighter players and taller players experienced higher mean head accelerations compared with heavier players and shorter players. Understanding the factors influencing HIE during contact events in football may help inform methods to reduce head injury risk.
Daniella M. DiGuglielmo, Mireille E. Kelley, Mark A. Espeland, Zachary A. Gregory, Tanner D. Payne, Derek A. Jones, Tanner M. Filben, Alexander K. Powers, Joel D. Stitzel, and Jillian E. Urban
Philip J. Morgan, Clare E. Collins, Alyce T. Barnes, Emma R. Pollock, Stevie-Lee Kennedy, Ryan J. Drew, Kristen L. Saunders, Jacqueline A. Grounds, Anna T. Rayward, and Myles D. Young
Background: Few lifestyle programs for young children have targeted fathers. This study examined the feasibility of a lifestyle intervention for fathers and their preschool-aged children. Method: A total of 24 father/preschool child dyads were recruited from Newcastle, Australia, into a single-arm, feasibility trial (baseline and 3-mo postbaseline assessments). The 9-session program aimed to improve physical activity and dietary habits of fathers and children. A priori feasibility benchmarks targeted recruitment (15 dyads), eligibility rate (>60%), attendance (80%), retention (≥85%), and program acceptability (≥4 out of 5). Acceptability of data collection procedures, research team program/resource management, home-program compliance, and preliminary intervention outcomes were also assessed. Results: Feasibility benchmarks were surpassed for recruitment (24 dyads), eligibility rate (61.5%), attendance (89%), retention (100%), and program acceptability (4.6 out of 5). Data collection procedures were acceptable. Challenges included mothers reporting their own dietary intake rather than their child’s, children moving during body composition measurement, and resetting pedometers. Resource and program management were excellent. Most families met home-program requirements (83%). Preliminary intervention outcomes were encouraging for fathers and children. Conclusion: Program feasibility was demonstrated by excellent recruitment, attendance, acceptability, retention, program administration, and promising preliminary intervention outcomes. A few data collection difficulties were identified. A larger scale efficacy trial is warranted.
Meena Makhija, Jasobanta Sethi, Chitra Kataria, Harpreet Singh, Paula M. Ludewig, and Vandana Phadke
Two-dimensional fluoroscopic imaging allows measurement of small magnitude humeral head translations that are prone to errors due to optical distortion, out-of-plane imaging, repeated manual identification of landmarks, and magnification. This article presents results from in vivo and in vitro fluoroscopy-based experiments that measure the errors and variability in estimating the humeral head translated position in true scapular plane and axillary views. The errors were expressed as bias and accuracy. The variability with repeated digitization was calculated using the intraclass correlation coefficient (ICC) and the standard error of measurement. Optical distortion caused underestimation of linear distances. The accuracy was 0.11 and 0.43 mm for in vitro and in vivo experiments, respectively, for optical distortion. The intrarater reliability was excellent for both views (ICC = .94 and .93), and interrater reliability was excellent (ICC = .95) for true scapular view but moderate (ICC = .74) for axillary views. The standard error of measurement ranged from 0.27 to 0.58 mm. The accuracy for the humeral head position in 10° out of true scapular plane images ranged from 0.80 to 0.87 mm. The current study quantifies the magnitude of error. The results suggest that suitable measures could be incorporated to minimize errors and variability for the measurement of glenohumeral parameters.
Joanna Horne, Nichola Kentzer, Lee Smith, Mike Trott, and Jitka Vseteckova
Background: It is estimated that 17% of the UK adult population are informal carers, usually for a family member, with a majority reporting that they are not able to engage in physical activity as much as they would like. The aim of this review is to provide a greater understanding of the prevalence of, and barriers and facilitators to, physical activity of informal carers in the United Kingdom. Methods: A systematic review of relevant databases and grey literature was undertaken, following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidance, from its inception until July 17, 2020. Results: Barriers to physical activity include increasing aging, not wanting to leave the caree alone, the caree being unable to take part in activities, health conditions, fatigue, lack of time, and difficulties in changing the routine for the caree. Facilitators include an appreciation of the benefits of engaging in exercise, previous participation in activities, group activities with similar people, and having some free time. Conclusions: Due to the paucity of research into the prevalence of, and barriers and facilitators to, physical activity in informal carers in the United Kingdom, this systematic review highlights the need for further research, focusing primarily on the physical activity of informal carers caring for individuals with a range of conditions. A further systematic review exploring these issues internationally is warranted.
Katherine A.J. Daniels, Eleanor Drake, Enda King, and Siobhán Strike
Cutting maneuvers can be executed at a range of angles and speeds, and these whole-body task descriptors are closely associated with lower-limb mechanical loading. Asymmetries in angle and speed when changing direction off the operated and nonoperated limbs after anterior cruciate ligament reconstruction may therefore influence the interpretation of interlimb differences in joint-level biomechanical parameters. The authors hypothesized that athletes would reduce center-of-mass heading angle deflection and body rotation during the change-of-direction stance phase when cutting from the operated limb, and would compensate for this by orienting their center-of-mass trajectory more toward the new intended direction of travel prior to touchdown. A total of 144 male athletes 8 to 10 months after anterior cruciate ligament reconstruction performed a maximum-effort sidestep cutting maneuver while kinematic, kinetic, and ground reaction force data were recorded. Peak ground reaction force and knee joint moments were lower when cutting from the operated limb. Center-of-mass heading angle deflection during stance phase was reduced for cuts performed from the operated limb and was negatively correlated with heading angle at touchdown. Between-limb differences in body orientation and horizontal velocity at touchdown were also observed. These systematic asymmetries in cut execution may require consideration when interpreting joint-level interlimb asymmetries after anterior cruciate ligament reconstruction and are suggestive of the use of anticipatory control to co-optimize task achievement and mechanical loading.
Jose A. Rodríguez-Marroyo, Beltrán González, Carl Foster, Ana Belén Carballo-Leyenda, and José G. Villa
Purpose: This study investigated the effect of cooldown modality (active vs passive) and duration (5, 10, and 15 min) on session rating of perceived exertion (sRPE). Secondarily, the possible influence of training sessions’ demand on this effect was studied. Methods: A total of 16 youth male soccer players (15.7 [0.4] y) completed 2 standardized training sessions per week across 6 weeks. During weeks 1 to 2, 3 to 4, and 5 to 6, cooldown lengths of 15, 10, and 5 minutes were studied, respectively. Using a crossover design, players were randomly assigned to 2 groups and each group performed 1 of 2 different cooldown interventions. Passive and active cooldown interventions based on static stretching and running exercises were studied. Heart rate and sRPE were recorded during all training sessions. Results: The lowest sRPE was observed when passive cooldown was performed. When the hardest training sessions were considered, a significant main effect of cooldown modality (P < .01) and duration (P < .05) and an interaction effect between these variables (P < .05) on sRPE were obtained. The lowest (P < .01) sRPE was observed during the longest cooldown (15 min). Conclusion: The findings suggest that sRPE may be sensitive to the selected cooldown modality and duration, especially following the most demanding training sessions.
Grégoire P. Millet, Rosalie Trigueira, Frédéric Meyer, and Marcel Lemire
Aims: It has been hypothesized that altitude training may alter running mechanics due to several factors such as the slower training velocity with associated alteration in muscle activation and coordination. This would lead to an altered running mechanics attested by an increase in mechanical work for a given intensity and to the need to “re-establish” the neuromuscular coordination and running biomechanics postaltitude. Therefore, the present study aimed to test the hypothesis that “live high—train high” would induce alteration in the running biomechanics (ie, longer contact time, higher vertical oscillations, decreased stiffness, higher external work). Methods: Before and 2 to 3 days after 3 weeks of altitude training (1850–2200 m), 9 national-level middle-distance (800–5000 m) male runners performed 2 successive 5-minute bouts of running at moderate intensity on an instrumented treadmill with measured ground reaction forces and gas exchanges. Immediately after the running trials, peak knee extensor torque was assessed during isometric maximal voluntary contraction. Results: Except for a slight (−3.0%; P = .04) decrease in vertical stiffness, no mechanical parameters (stride frequency and length, contact and flight times, ground reaction forces, and kinetic and potential work) were modified from prealtitude to postaltitude camp. Running oxygen cost was also unchanged. Discussion: The present study is the first one to report that “live high—train high” did not change the main running mechanical parameters, even when measured immediately after the altitude camp. This result has an important practical implication: there is no need for a corrective period at sea level for “normalizing” the running mechanics after an altitude camp.
Christa Spicer and Daniel B. Robinson
Feelings of isolation have long been found to be experienced by many teachers, particularly by those within some specialist disciplines, including physical education (PE). The potential effects of teacher isolation are undesirable and plentiful. They include a lessening of interest in one’s work, burnout, and/or an absence of community connection. Given the uniqueness of their discipline, PE teachers may especially be impacted by the following: Their discipline is “low status” and marginalized, they are frequently both physically and psychologically isolated from their peers, and they often are one of very few PE specialists in a school. Given these sorts of unique challenges for PE teachers, the authors undertook a scoping review of literature in order to gather and provide a comprehensive and up-to-date account of peer-reviewed literature related to PE teachers and isolation, as well as offer implications for PE research and practice.
Reuben G. Stables, Andreas M. Kasper, S. Andy Sparks, James P. Morton, and Graeme L. Close
The remote food photography method, often referred to as “Snap-N-Send” by sport nutritionists, has been reported as a valid method to assess energy intake in athletic populations. However, preliminary studies were not conducted in true free-living conditions, and dietary assessment was performed by one researcher only. The authors, therefore, assessed the validity of Snap-N-Send to assess the energy and macronutrient composition in experienced (EXP, n = 23) and inexperienced (INEXP, n = 25) sport nutritionists. The participants analyzed 2 days of dietary photographs, comprising eight meals. Day 1 consisted of “simple” meals based around easily distinguishable foods (i.e., chicken breast and rice), and Day 2 consisted of “complex” meals, containing “hidden” ingredients (i.e., chicken curry). The estimates of dietary intake were analyzed for validity using one-sample t tests and typical error of estimates (TEE). The INEXP and EXP nutritionists underestimated energy intake for the simple day (mean difference [MD] = −1.5 MJ, TEE = 10.1%; −1.2 MJ, TEE = 9.3%, respectively) and the complex day (MD = −1.2 MJ, TEE = 17.8%; MD = −0.6 MJ, 14.3%, respectively). Carbohydrate intake was underestimated by INEXP (MD = −65.5 g/day, TEE = 10.8% and MD = −28.7 g/day, TEE = 24.4%) and EXP (MD = −53.4 g/day, TEE = 10.1% and −19.9 g/day, TEE = 17.5%) for both the simple and complex days, respectively. Interpractitioner reliability was generally “poor” for energy and macronutrients. The data demonstrate that the remote food photography method/Snap-N-Send underestimates energy intake in simple and complex meals, and these errors are evident in the EXP and INEXP sport nutritionists.
Joanne A. McVeigh, Jennifer Ellis, Caitlin Ross, Kim Tang, Phoebe Wan, Rhiannon E. Halse, Satvinder Singh Dhaliwal, Deborah A. Kerr, and Leon Straker
Activity trackers provide real-time sedentary behavior (SB) and physical activity (PA) data enabling feedback to support behavior change. The validity of activity trackers in an obese population in a free-living environment is largely unknown. This study determined the convergent validity of the Fitbit Charge 2 in measuring SB and PA in overweight adults. The participants (n = 59; M ± SD: age = 48 ± 11 years; body mass index = 34 ± 4 kg/m2) concurrently wore a Charge 2 and ActiGraph GT3X+ accelerometer for 8 days. The same waking wear periods were analyzed, and standard cut points for GT3X+ and proprietary algorithms for the Charge 2, together with a daily step count, were used. Associations between outputs, mean difference (MD) and limits of agreement (LOA), and relative differences were assessed. There was substantial association between devices (intraclass correlation coefficients from .504, 95% confidence interval [.287, .672] for SB, to .925, 95% confidence interval [.877, .955] for step count). In comparison to the GT3X+, the Charge 2 overestimated SB (MD = 37, LOA = −129 to 204 min/day), moderate to vigorous PA (MD = 15, LOA = −49 to 79 min/day), and steps (MD = 1,813, LOA = −1,066 to 4,691 steps/day), and underestimated light PA (MD = −32, LOA = −123 to 58 min/day). The Charge 2 may be a useful tool for self-monitoring of SB and PA in an overweight population, as mostly good agreement was demonstrated with the GT3X+. However, there were mean and relative differences, and the implications of these need to be considered for overweight adult populations who are already at risk of being highly sedentary and insufficiently active.