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Open access

Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke

This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.

Open access
Open access

Sara Oliveira, Marina Cunha, António Rosado, and Cláudia Ferreira

This study aimed to test a model that hypothesized that the compassionate coach, as perceived by the athletes, has an impact on athlete-related social safeness and psychological health, through shame and self-criticism. The sample comprised 270 Portuguese adult athletes, who practiced different competitive sports. The path analysis results confirmed the adequacy of the proposed model, which explained 45% of the psychological health’s variance. Results demonstrated that athletes who perceive their coaches as more compassionate tend to present higher levels of social safeness (feelings of belonging to the team) and of psychological health, through lower levels of shame and self-criticism. These novel findings suggest the importance of the adoption of supportive, warm, safe, and compassionate attitudes from coaches in athletes’ mental health. This study also offers important insights by suggesting that feelings of acceptance and connectedness in team relationships may be at the root of athletes’ emotional processes and well-being.

Open access

Heitor O. Santos, Gederson K. Gomes, Brad J. Schoenfeld, and Erick P. de Oliveira

Whole egg may have potential benefits for enhancing muscle mass, independent of its protein content. The yolk comprises ∼40% of the total protein in an egg, as well as containing several nonprotein nutrients that could possess anabolic properties (e.g., microRNAs, vitamins, minerals, lipids, phosphatidic acid and other phospholipids). Therefore, the purpose of this narrative review is to discuss the current evidence as to the possible effects of egg yolk compounds on skeletal muscle accretion beyond those of egg whites alone. The intake of whole egg seems to promote greater myofibrillar protein synthesis than egg white intake in young men. However, limited evidence shows no difference in muscle hypertrophy when comparing the consumption of whole egg versus an isonitrogenous quantity of egg white in young men performing resistance training. Although egg yolk intake seems to promote additional acute increases on myofibrillar protein synthesis, it does not seem to further enhance muscle mass when compared to egg whites when consumed as part of a high-protein dietary patterns, at least in young men. This conclusion is based on very limited evidence and more studies are needed to evaluate the effects of egg yolk (or whole eggs) intake on muscle mass not only in young men, but also in other populations such as women, older adults, and individuals with muscle wasting diseases.

Open access

Linda S. Pescatello, Emily A. Hennessy, Peter T. Katzmarzyk, William E. Kraus, Anne F. Fish, Lynette L. Craft, and Blair T. Johnson

Background: Systematic reviews (SRs) and meta-analyses (MAs) have proliferated with a concomitant increase in reviews of SRs/MAs or “meta-reviews” (MRs). As uncovered by the 2018 US Physical Activity Guidelines Advisory Committee (PAGAC), there is a paucity of best practice guidance on MRs on physical activity health-related research. This manuscript aims to fill this gap. Methods: In total, the PAGAC conducted 38 literature searches across 3 electronic databases and triaged 20,838 titles, 4913 abstracts, and 2139 full texts from which 1130 articles qualified for the PAGAC Scientific Report. Results: During the MR process, the following challenges were encountered: (1) if the SR/MA authors had limited experience in synthesis methodology, they likely did not account for risk of bias in the conclusions they reached; (2) many SRs/MAs reviewed the same primary-level studies; (3) many SRs/MAs failed to disclose effect modifier analyses; (4) source populations varied; (5) physical activity exposures were nonstandardized; and (6) dose–response effects or effect modification of the physical activity exposure could not be identified. Conclusions: Using examples from the PAGAC Scientific Report, we provide (1) a high-level introduction to MRs; (2) recommended steps in conducting a MR; (3) challenges that can be encountered; and (4) guidance in addressing these challenges.

Open access

Matthew A. Ladwig, Christopher N. Sciamanna, Brandon J. Auer, Tamara K. Oser, Jonathan G. Stine, and Jennifer P. Agans

Background: Few Americans accumulate enough physical activity (PA) to realize its benefits. Understanding how and why individuals use their discretionary time for different forms of PA could help identify and rectify issues that drive individuals away from certain physical activities, and leverage successful strategies to increase participation in others. Methods: The authors analyzed approximately 30 years of changes in PA behavior by intensity, type, and mode, using data from the Behavioral Risk Factor Surveillance System. Results: Since 1988, the proportions of adults most frequently engaging in exercise, sport, or lifestyle physical activity have changed noticeably. The most apparent changes from 1988 to 2017 were the proportions most frequently engaging in Exercise and Sport. In addition, the proportion of time reportedly spent in vigorous-intensity PA decreased over time, particularly among male respondents. Moreover, the proportion of Americans reporting an “Other” PA mode increased substantially, suggesting a growing need for a greater variety of easily accessible options for adult PA. Conclusions: Over time, a smaller proportion of American adults reported participating in sport and exercise modalities and reported engaging more frequently in low-intensity physical activities.

Open access

Katie Slattery, Stephen Crowcroft, and Aaron J. Coutts

Open access

Sandra K. Hnat, Musa L. Audu, Ronald J. Triolo, and Roger D. Quinn

Estimating center of mass (COM) through sensor measurements is done to maintain walking and standing stability with exoskeletons. The authors present a method for estimating COM kinematics through an artificial neural network, which was trained by minimizing the mean squared error between COM displacements measured by a gold-standard motion capture system and recorded acceleration signals from body-mounted accelerometers. A total of 5 able-bodied participants were destabilized during standing through: (1) unexpected perturbations caused by 4 linear actuators pulling on the waist and (2) volitionally moving weighted jars on a shelf. Each movement type was averaged across all participants. The algorithm’s performance was quantified by the root mean square error and coefficient of determination (R 2) calculated from both the entire trial and during each perturbation type. Throughout the trials and movement types, the average coefficient of determination was 0.83, with 89% of the movements with R 2 > .70, while the average root mean square error ranged between 7.3% and 22.0%, corresponding to 0.5- and 0.94-cm error in both the coronal and sagittal planes. COM can be estimated in real time for balance control of exoskeletons for individuals with a spinal cord injury, and the procedure can be generalized for other gait studies.

Open access

Scott McLean, Hugo A. Kerhervé, Nicholas Stevens, and Paul M. Salmon

Purpose: The broad aim of sport-science research is to enhance the performance of coaches and athletes. Despite decades of such research, it is well documented that sport-science research lacks empirical evidence, and critics have questioned its scientific methods. Moreover, many have pointed to a research–practice gap, whereby the work undertaken by researchers is not readily applied by practitioners. The aim of this study was to use a systems thinking analysis method, causal loop diagrams, to understand the systemic issues that interact to influence the quality of sport-science research. Methods: A group model-building process was utilized to develop the causal loop diagram based on data obtained from relevant peer-reviewed literature and subject-matter experts. Results: The findings demonstrate the panoply of systemic influences associated with sport-science research, including the existence of silos, a focus on quantitative research, archaic practices, and an academic system that is incongruous with what it actually purports to achieve. Conclusions: The emergent outcome of the interacting components is the creation of an underperforming sport-science research system, as indicated by a lack of ecological validity, translation to practice, and, ultimately, a research–practice gap.