Although 24-hour time-use data are increasingly being examined in relation to indices of health, consensus has yet to be reached about the best way to present estimates from compositional analyses. This analysis explored the impact of different presentations of results when assessing the relationship between 24-hour time-use and body mass index (BMI) z-score using compositional analysis of 5-day actigraphy data in 742 children. First it was found that reallocating non-wear time to day-time components only (sedentary behavior, light physical activity, and moderate-to-vigorous physical activity [MVPA]) before normalization to 24 hours provided stronger estimates with BMI z-score than simply removing non-wear time before normalization. Estimates for sleep time were substantially affected, where associations with BMI z-score nearly doubled (mean difference [95% CI] in BMI z-score for 10% longer sleep were −0.20 [−0.32, −0.08] compared to −0.11 [−0.23, 0.002]). Presenting estimates in terms of a greater number of minutes in a component, relative to all others, showed MVPA to be the strongest predictor of BMI z-score, while estimates in terms of the proportion of minutes showed sleep to be the strongest predictor. Both presentations have value. However, presentations in terms of one-to-one “substitutions” of time may need careful interpretation due to the uneven distribution of time in each component. In conclusion, when analyzing relationships between 24-hour time-use and health outcomes, non-wear time and presentation of estimates can impact final conclusions. As a result, the current understanding of the importance of sleep for child health may be underestimated.
Jillian J. Haszard, Kim Meredith-Jones, Victoria Farmer, Sheila Williams, Barbara Galland and Rachael Taylor
Stephanie Field, Jeff Crane, Patti-Jean Naylor and Viviene Temple
Children who underestimate their physical abilities have lower motivation, higher anxiety, and lack of understanding as to why they may be succeeding or struggling in sports settings, which can result in withdrawal from physical activities. Theoretically, middle childhood is a time when perceptions of physical competence (PPC) become more accurate as children develop the cognitive capacity to interpret new sources of feedback and develop a realistic sense of their physical abilities. The purpose of this study was to investigate the extent to which accuracy of PPC changed from grade 2 to grade 4. Participants were 238 boys and girls (M age = 7.8 yrs) from eight participating elementary schools in Victoria, British Columbia, Canada. The Test of Gross Motor Development–Second Edition was used to assess motor skills. PPC were assessed using the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (for grade 2) and the Self-Perception Profile for Children (for grades 3 and 4). Results revealed that participants who underestimated or overestimated their physical competence in grade 2 saw an improvement in accuracy, and, by grade 4, had similar accuracy scores to their peers who were considered ‘accurate’ estimators. These results reinforce theory that suggests PPC become more accurate in middle childhood.
Mayrena I. Hernandez, Kevin M. Biese, Dan A. Schaefer, Eric G. Post, David R. Bell and M. Alison Brooks
Context: Sport specialization among youth athletes has been associated with increased risk of overuse injuries. Previous research demonstrates that children perceive specialization to be beneficial in making their high school team and receiving athletic college scholarships. Previous research demonstrates that parents play a significant role in their child’s sport experience. However, it is unknown if parents and children answer questions related to specialization factors in a similar manner. Objective: To evaluate the beliefs of youth athletes and parents on factors related to sport specialization and evaluate the level of agreement between dyads on sports specialization. Design: Cross-sectional. Setting: Online and paper surveys. Patients or Other Participants: Aim 1: 1998 participants (993 children and 1005 parents). Aim 2: 77 paired parent–child dyads. Interventions: Self-administered survey. Main Outcome Measures: The responses were summarized via frequency and proportions (%). Chi-squares were calculated between parent and child responses. Kappa coefficients were calculated for dyads to determine level of agreement. Sport specialization was classified using a common 3-point scale. Results: The parents were more concerned about risk of injury in sports compared with children (P < .001, χ2 = 231.4; parent: extremely: 7.1%; child: extremely: 3.7%). However, children were more likely to believe that specialization was associated with their chances of obtaining an athletic college scholarship compared with parents (P < .001, χ2 = 201.6; parent: very/extremely likely: 13.7%; child: very/extremely likely: 15.8%). Dyad subanalysis indicated a moderate level of agreement for “quitting other sports to focus on one sport” (κ = .50) and a low level of agreement for “identifying a primary sport” (κ = .30) and “training >8 months per year in primary sport” (κ = .32). Conclusions: Parents and youth athletes had differing beliefs on the factors related to sport specialization. Dyad analysis shows that parents and children answer sport specialization classification questions differently. Health care providers should be aware of these differences, and messaging should be individualized to the audience.
Theodore Kent Kessinger, Bridget Melton, Theresa Miyashita and Greg Ryan
Clinical Scenario: Manipulation of exercise variables in resistance training (RT) is an important component in the development of muscular strength, power, and hypertrophy. Currently, most research centers on untrained or recreationally trained subjects. This critically appraised topic focuses on studies that center on the well-trained subject with regard to frequency of training. Clinical Question: In well-trained male subjects, is there an association between RT frequency and the development of muscular strength and hypertrophy? Summary of Key Findings: Four studies met the inclusion criteria and were included for analysis. All studies showed that lower-frequency training could elicit muscular strength and hypertrophy increases. One study suggested that a higher frequency compared with a lower frequency may provide a slight benefit to hypertrophic development. One study reported a greater level of delayed onset muscle soreness with lower frequency training. The 4 studies demonstrate support for the clinical question. Clinical Bottom Line: Current evidence suggests that lower-frequency RT produces equal to greater improvements on muscular strength and hypertrophy in comparison to higher-frequency RT when volume is equated. The evidence is particularly convincing when lower-frequency RT is associated with a total-body training protocol in well-trained male subjects. Strength of Recommendation: There is moderate-to-strong evidence to suggest that lower-frequency RT, when volume is equated, will produce equal to greater improvements on muscular strength and hypertrophy in comparison to higher-frequency RT.
Mustafa Sarkar and Nathan K. Hilton
Although there is burgeoning research on resilience in elite athletes, there has been no empirical investigation of resilience in elite coaches. The purpose of this study was to explore psychological resilience in world-class coaches and how they develop resilience in athletes. A longitudinal qualitative design was adopted due to the dynamic and temporal nature of resilience. Five Olympic medal–winning coaches (four males and one female) were interviewed twice over a 12-month swimming season. Reflexive thematic analysis was employed to analyze the data. Findings revealed 14 higher order themes, which were categorized into the following three general dimensions: coach stressors (managing the Olympic environment, preparation for major events, coach personal well-being, directing an organization); coach protective factors (progressive coaching, coaching support network, maintaining work/life balance, secure working environment, durable motivation, effective decision making); and enhancing resilience in athletes (developing a strong coach–athlete relationship, creating a facilitative environment, developing a resilience process, athlete individual factors). The results are presented to demonstrate the interplay between coach stressors and protective factors over time, which offers an original and significant contribution to the resilience literature by providing a unique insight into the dynamic and temporal nature of resilience in Olympic medal–winning coaches.
Amelia J. Carr, Philo U. Saunders, Laura A. Garvican-Lewis and Brent S. Vallance
Purpose: To quantify, for an elite-level racewalker, altitude training, heat acclimation and acclimatization, physiological data, and race performance from January 2007 to August 2008. Methods: The participant performed 7 blocks of altitude training: 2 “live high:train high” blocks at 1380 m (total = 22 d) and 5 simulated “live high:train low” blocks at 3000 m/600 m (total = 98 d). Prior to the 2007 World Championships and the 2008 Olympic Games, 2 heat-acclimation blocks of ~6 weeks were performed (1 session/week), with ∼2 weeks of heat acclimatization completed immediately prior to each 20-km event. Results: During the observation period, physiological testing included maximal oxygen uptake (VO2max, mL·kg−1·min−1), walking speed (km·h−1) at 4 mmol·L−1 blood lactate concentration [La−], body mass (kg), and hemoglobin mass (g), and 12 × 20-km races and 2 × 50-km races were performed. The highest VO2max was 67.0 mL·kg−1·min−1 (August 2007), which improved 3.1% from the first measurement (64.9 mL·kg−1·min−1, June 2007). The highest percentage change in any physiological variable was 7.1%, for 4 mmol·L−1 [La−] walking speed, improving from 14.1 (June 2007) to 15.1 km·h−1 (August 2007). Personal-best times for 20 km improved from (hh:mm:ss) 1:21:36 to 1:19:41 (2.4%) and from 3:55:08 to 3:39:27 (7.1%) in the 50-km event. The participant won Olympic bronze and silver medals in the 20- and 50-km, respectively. Conclusions: Elite racewalkers who regularly perform altitude training may benefit from periodized heat acclimation and acclimatization prior to major international competitions in the heat.
Abbey Thomas and Jeffrey B. Driban
Jennifer L. Rizzo
The diagnosis of thoracic outlet syndrome (TOS) is challenging and primarily determined by clinical examination. Symptoms such as numbness and tingling in the arms when raised above the head make the rehabilitation process difficult due to the various manifestations of TOS presented to the athletic trainer (AT). An AT should understand the intricate anatomical characteristics of the thoracic outlet and how various TOS presentations may impact treatment. In this clinical commentary, I provide my own insights for understanding TOS from my perspective as a patient and AT. These insights are valuable when making diagnostic, therapeutic, and prognostic clinical decisions.
Emily R. Hunt, Cassandra N. Parise and Timothy A. Butterfield
Clinical Scenario: Anterior cruciate ligament (ACL) ruptures are one of the most common injuries in young athletic populations. The leading treatment for these injuries is ACL reconstruction (ACL-r); however, nonoperative treatments are also utilized. Following ACL-r, patients experience prolonged muscle weakness and atrophy of the quadriceps muscle group, regardless of rehabilitation. Nonoperative treatment plans following ACL injury exist, but their outcomes are less familiar, in spite of providing insight as a nonsurgical “control” for postsurgical rehabilitation outcomes. Therefore, the purpose of this critically appraised topic was to evaluate quadriceps strength and function following nonoperative ACL rehabilitation using objective and subjective measures including isokinetic dynamometry, the single-leg hop test, and the International Knee Documentation Committee (IKDC) subjective knee form. Focused Clinical Question: What are the effects of nonoperative treatment on peak isokinetic knee-extensor torque, the single-leg hop tests, and the IKDC in patients who have sustained an ACL rupture? Summary of Key Findings: Patients who underwent nonsurgical ACL treatment produced limb symmetry index, with the side-to-side torque difference expressed as a percentage, and values at or above 90% for all 4 single-leg hop tests and strength tests similar to ACL-r patients. All studies showed individuals had higher IKDC scores at baseline collection when compared with patients who underwent ACL-r but showed lower IKDC scores at long-term follow-up compared with ACL-r patients. Clinical Bottom Line: Nonoperative treatments of ACL injuries yield similar long-term results in quadriceps strength as ACL-r. Due to the quality of evidence and the absence of randomized controlled trials on this topic, these outcomes should be considered with caution. Strength of Recommendation: The Oxford Centre for Evidence-Based Medicine taxonomy recommends a grade of B for level 2 evidence with consistent findings.