Very little is known about how long-term (>6 months) adaptation to a low-carbohydrate, high-fat (LCHF) diet affects insulin signaling in healthy, well-trained individuals. This study compared glucose tolerance; skeletal muscle glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) content; and muscle enzyme activities representative of the main energy pathways (3-hydroxyacetyl-CoA dehydrogenase, creatine kinase, citrate synthase, lactate dehydrogenase, phosphofructokinase, phosphorylase) in trained cyclists who followed either a long-term LCHF or a mixed-macronutrient (Mixed) diet. On separate days, a 2-hr oral glucose tolerance test was conducted, and muscle samples were obtained from the vastus lateralis of fasted participants. The LCHF group had reduced glucose tolerance compared with the Mixed group, as plasma glucose concentrations were significantly higher throughout the oral glucose tolerance test and serum insulin concentrations peaked later (LCHF, 60 min; Mixed, 30 min). Whole-body insulin sensitivity was not statistically significantly different between groups (Matsuda index: LCHF, 8.7 ± 3.4 vs. Mixed, 12.9 ± 4.6; p = .08). GLUT4 (LCHF: 1.13 ± 0.24; Mixed: 1.44 ± 0.16; p = .026) and IRS1 (LCHF: 0.25 ± 0.13; Mixed: 0.46 ± 0.09; p = .016) protein content was lower in LCHF muscle, but enzyme activities were not different. We conclude that well-trained cyclists habituated to an LCHF diet had reduced glucose tolerance compared with matched controls on a mixed diet. Lower skeletal muscle GLUT4 and IRS1 contents may partially explain this finding. This could possibly reflect an adaptation to reduced habitual glucose availability rather than the development of a pathological insulin resistance.
Christopher C. Webster, Kathryn M. van Boom, Nur Armino, Kate Larmuth, Timothy D. Noakes, James A. Smith and Tertius A. Kohn
Katrina L. Piercy, Frances Bevington, Alison Vaux-Bjerke, Sandra Williams Hilfiker, Sean Arayasirikul and Elizabeth Y. Barnett
Background: The Office of Disease Prevention and Health Promotion completed research to understand factors that could encourage Americans to follow the Physical Activity Guidelines for Americans, second edition, released in 2018. This study describes survey research assessing demographic characteristics that might be related to knowledge and awareness of the guidelines. Methods: An online survey of 2050 adult physical activity contemplators assessed knowledge of physical activity, awareness of the guidelines, and knowledge of dosage recommendations. Univariate and bivariate analyses were performed, and demographic differences in knowledge and awareness were analyzed using Pearson chi-square tests and Fisher exact tests. Results: Respondents had medium to high knowledge of physical activity, although knowledge varied significantly by socioeconomic factors. Knowledge of dosage recommendations was very low, with 2% and 3% of respondents correctly identifying recommended moderate- and vigorous-intensity doses, respectively. Only 22% were aware of the guidelines; awareness was greater among those with a higher education or income and those without a disability. Conclusions: These findings guided the development of the Office of Disease Prevention and Health Promotion’s Move Your Way campaign and reinforced the need to raise awareness of the guidelines and promote behavior change among physical activity contemplators—particularly those from lower socioeconomic groups.
Sergei Iljukov, Jukka-Pekka Kauppi, Arja L.T. Uusitalo, Juha E. Peltonen and Yorck O. Schumacher
The purpose of this research was to evaluate the performances of female middle- and long-distance runners before and after the implementation of a new antidoping strategy (the Athlete Biological Passport [ABP]) in a country accused of systematic doping. A retrospective analysis of the results of Russian National Championships from 2008 to 2017 was performed. The 8 best female performances for the 800-m, 1500-m, 3000-m steeplechase, 5000-m, and 10,000-m events from the semifinals and finals were analyzed. The yearly number of athletes fulfilling standard qualifications for international competitions was also evaluated. Overall, numbers of athletes banned for doping in 2008–2017 were calculated. As a result, 4 events (800, 1500, 5000 [all P < .001], and 10,000 m [P < .01]) out of 5 showed statistically significant deterioration in the performances when comparing before and after the introduction of the ABP. The 3000-m steeplechase was the only event that did not show statistically significant change. The highest relative decrease in the number of runners who met standard qualification for international competition was for the 5000-m event (46%), followed by 1500-m (42%), 800-m (38%), 10,000-m (17%), and 3000-m steeplechase (1%). In conclusion, implementation of the ABP was followed by a significant reduction in the performance of female runners in a country accused of systematic doping. It can be reasonably speculated that more stringent antidoping testing, more specifically the introduction of the ABP, is a key reason for this reduction.
Brian P. McCullough, Madeleine Orr and Timothy Kellison
The relationship between sport and the natural environment is bidirectional and critical to the production of sport products, events, and experiences. Researchers have studied sport and the natural environment within the various subdisciplines of sport management. However, given the changing climate and mounting public concern for the environment, there is pressure to reconsider the relevance and significance of the natural environment, which is taken for granted in managerial contexts. Reflecting the importance of the natural environment, the robustness of the current literature, and the potential for the future, we propose a new subdiscipline of sport management called sport ecology. Thus, we proposed, in this paper, a definition for sport ecology, (re)introduced key concepts related to this subdiscipline (e.g., sustainability, green), and highlighted the leading research that serves as the foundation for sport ecology. We concluded with a discussion on the ways sport ecology can inform—and be informed by—other subdisciplines of sport management.
Eric P. Scibek, Matthew F. Moran and Susan L. Edmond
Context: The deep squat (DS) test is a component of the functional movement screen, which is used to assess the quality of fundamental movement patterns; however, the accuracy of the DS has not been studied. The DS is a complex, total body movement pattern with evaluation required at several points along the kinematic chain. Objective: To assess the accuracy of DS scoring by an athletic trainer, physical therapist, and exercise science professional via a comparative analysis with kinematic data (KD) and to identify scoring criteria that would improve agreement between raters and KD scores. Design: Cross-sectional study. Setting: Motion analysis laboratory. Participants: A rater from each of 3 movement science disciplines rated the DS of 23 male college athletes (20.3 [1.2] y; 70.5 [3.5] kg). Interventions: Subjects were outfitted with reflective markers and asked to perform the DS. The DS performance was scored by 3 raters and kinematic analysis. Subsequently, the optimal set of criteria that minimized the difference between mode rater score and KD was determined via a Nelder–Mead simplex optimization routine. Main Outcome Measures: Intraclass correlation coefficients (ICCs) were calculated using SPSS (version 23; IBM, Armonk, NY) to determine tester agreement with the KD score and between the mode score and KD score. Results: Agreement was poor for the athletic trainer (ICC = .387), physical therapist (ICC = .298), exercise science professional (ICC = .378), and raters’ DS scores when compared with the KD. Agreement was poor for the mode score when compared with KD prior to optimization and good following optimization (ICC = .830), thereby allowing identification of specific scoring errors. Conclusions: Agreement for DS scores is poor when compared with KD; however, it may be improved with optimization of DS scoring criteria.
Jessica St Aubin, Jennifer Volberding and Jack Duffy
Clinical Question: How does early return to physical activity impact return-to-play recovery time in patients 5–30 years old after an acute concussion as compared to the current best practice of resting? Clinical Bottom Line: Based on the information gathered, there is moderate evidence to support the incorporation of light to moderate physical activity within 7 days after a concussion in order to decrease recovery time and symptoms.
Frances Bevington, Katrina L. Piercy, Kate Olscamp, Sandra W. Hilfiker, Dena G. Fisher and Elizabeth Y. Barnett
Background: The Move Your Way campaign, developed by the Office of Disease Prevention and Health Promotion, aims to improve Americans’ adherence to the Physical Activity Guidelines for Americans. This article describes the research that informed the campaign’s products, messaging, and strategy. Methods: A mixed-methods approach was used to understand participants’ preferences for physical activity messages and information seeking. Two rounds (round 1 [n = 95] and round 2 [n = 73]) of focus groups and an online survey (n = 2050) were conducted with adult physical activity contemplators. A third round (n = 84) of focus groups was conducted with children, teens, and parents of young children. Results: Adults, parents, teens, and children preferred messages that reflected diverse examples of activities; most participants disliked “one-size-fits-all” recommendations. Adults and parents preferred messages that emphasized specific health benefits over generic messages about overall health. Although some participants preferred getting physical activity information from digital search tools and social media platforms, many preferred getting this information from family members and friends. Conclusion: The Office of Disease Prevention and Health Promotion translated these findings into 3 themes used for Move Your Way implementation: (1) leverage social and community connections, (2) emphasize representation through inclusion and diversity, and (3) customize physical activity recommendations to make them more achievable.
Dean Barker, Gunn Nyberg and Hakan Larsson
Purpose: To describe student learning when physical education teacher and students attempted to develop movement capability. Methods: The study reports on the implementation of a 10-lesson pedagogical sequence. Data were generated using observations, interviews, and student diaries with one grade 9 class (26 students aged approximately 15 years) as they developed juggling capabilities. Data were analyzed using the notion of corporeal thresholds. Results: Results show that (a) a “throw–throw–catch–catch” pattern emerged as a corporeal threshold for juggling within the sequence; (b) most learners had crossed the threshold at the outset and were able to experiment with different forms of juggling during the sequence; (c) some students crossed the threshold during the sequence. These students experienced liminal phases, characterized by frustration and an initial feeling that they were juggling in the “wrong” way; and (d) some learners became stuck, pretended to know what to do, and did not cross the threshold during the 10 lessons. Discussion/Conclusion: Three issues related to the threshold approach are discussed: student identity and group membership, the process of learning, and the emotional dimensions of movement learning. This study is concluded with reflections on the implications of the results for scholarship.
Emily A. Hall, Dario Gonzalez and Rebecca M. Lopez
Clinical Question: Does the medical model of organizational structure compared to either the academic or traditional models have a greater influence on job satisfaction and quality of life in collegiate athletic trainers? Clinical Bottom Line: Based on the quality of the person-oriented evidence available, the recommendation to adopt the medical model for athletic training staff would receive a Strength of Recommendation Taxonomy (SORT) grade of B.