Liver L-glutamine is an important vehicle for the transport of ammonia and intermediary metabolism of amino acids between tissues, particularly under catabolic situations, such as high-intensity exercise. Hence, the aim of this study was to investigate the effects of oral supplementations with L-glutamine in its free or dipeptide forms (with L-alanine) on liver glutamine-glutathione (GSH) axis, and 70 kDa heat shock proteins (HSP70)/heat shock transcription factor 1 (HSF1) expressions. Adult male Wistar rats were 8-week trained (60 min/day, 5 days/week) on a treadmill. During the last 21 days, the animals were daily supplemented with 1 g of L-glutamine/kg body weight per day in either l-alanyl-L-glutamine dipeptide (DIP) form or a solution containing L-glutamine and l-alanine in their free forms (GLN+ALA) or water (controls). Exercise training increased cytosolic and nuclear HSF1 and HSP70 expression, as compared with sedentary animals. However, both DIP and GLN+ALA supplements enhanced HSF1 expression (in both cytosolic and nuclear fractions) in relation to exercised controls. Interestingly, HSF1 rises were not followed by enhanced HSP70 expression. DIP and GLN+ALA supplements increased plasma glutamine concentrations (by 62% and 59%, respectively) and glutamine to glutamate plasma ratio in relation to trained controls. This was in parallel with a decrease in plasma ammonium levels. Supplementations increased liver GSH (by 90%), attenuating the glutathione disulfide (GSSG) to GSH ratio, suggesting a redox state protection. In conclusion, oral administration with DIP and GLN+ALA supplements in endurance-trained rats improve liver glutamine-GSH axis and modulate HSF1 pathway.
Éder Ricardo Petry, Vinicius Fernandes Cruzat, Thiago Gomes Heck, Paulo Ivo Homem de Bittencourt Jr. and Julio Tirapegui
Joke Simons, Siegfried Dewitte and Willy Lens
This study tested the hypothesis that the reason a person engages in a physical education activity (instrumentality) has an effect on his or her state goal orientation, time spent practicing, task enjoyment, motivation, effort, and ultimately on his/her performance. Participants, 695 college students (340 M, 355 F; mean age 19.7 years, range = 18–22) who were enrolled in physical education classes, learned a dribble-shooting basketball task. Before practicing it for 20 minutes, they received one of the three instructions underlining the personal and/or future relevance of the task. Instructions emphasizing the obligatory nature of the task led to a decrease in motivated behavior, performance, and state task orientation, but an increase in the state ego orientation. Instructions emphasizing the personal and future relevance enhanced state task orientation, motivated behavior, and performance. Instructions that only emphasized personal relevance fell in between. The results of this study showed that instructions are powerful tools that can easily affect the quality of motivation and either strengthen or undermine students’ motivational behavior, performance, and future participation, at least when students have little or no experience with the task.
Nerissa Campbell, Anca Gaston, Casey Gray, Elaine Rush, Ralph Maddison and Harry Prapavessis
Accurate assessment of physical activity energy expenditure (PAEE) among adolescents is important for surveillance, evaluating interventions, and understanding the relation between energy balance and normal physiological and behavioral growth and development. The purpose of this study was to examine the validity of the Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH)13 for measuring PAEE among adolescents.
The participants were seventeen adolescents (9 females; Mean age = 17.53; SD = 0.62). Energy expenditure was measured during a 9-day period with doubly labeled water (DLW). The SQUASH was self-administered on the morning of the 10th day and assessed commuting activities, leisure time activities, household activities, and activities at work and school over the previous 9 days.
A Bland-Altman plot indicated that the SQUASH underestimated PAEE compared with DLW by a mean difference of 126 kcal·d−1 (95% limits of agreement: –1,207 to 1,459 kcal·d−1), representative of a 10% underestimation. The Spearman rank order correlation coefficient showed there was a significant association between the SQUASH and DLW (r = .50, P = .04), for estimating PAEE.
When using a sample of highly active adolescents, the SQUASH is a valid self-report tool for measuring PAEE at the group and individual rank order level.
Patricia Olaya-Contreras, Myriam Bastidas and Daniel Arvidsson
The aim of this study is to investigate associations of screen-time and physical activity (PA) with self-efficacy for PA, intrinsic motivation to PA and health-related quality of life (HRQoL) in Colombian schoolchildren from socioeconomically disadvantaged neighborhoods, and to compare these variables among children with normal-weight (NW), overweight (OW) and obesity (OB).
In 678 schoolchildren (age 10–14 years) screen-time (TV, video games, computer) and number of days being physically active ≥ 60 minutes were self-reported. Multi-item scales were used to assess self-efficacy to PA and intrinsic motivation to PA. The KIDSCREEN-27 was used to assess HRQoL.
Screen-time was associated with HRQoL in the school/learning environment dimension. Number of days being physically active was associated with self-efficacy for PA, intrinsic motivation for PA and with HRQoL concerning physical well-being, autonomy/parent relation and social support/peers. Group differences were found for days being physically active (OW = 2.8 and OB = 2.7 vs. NW = 3.3) but not for screen-time (NW = 5.0, OW = 4.7 and OB = 5.7 hrs·d-1). OW and OB scored lower on intrinsic motivation to PA than NW (OW = 19.2 and OB = 17.9 versus NW = 20.1). All 3 groups differed in physical well-being scores (NW = 50.3, OW = 48.1, OB = 40.6, P < .001).
Schoolchildren with overweight and obesity from socioeconomically disadvantaged neighborhoods need additional motivational support to perform health-enhancing PA to experience higher physical well-being.
Stephanie J. Hanrahan, Rachel Pedro and Ester Cerin
The purpose of this study was to determine if the use of structured self-reflection in community dance classes would influence achievement goal orientations, levels of intrinsic motivation, or perceived dance performance. The Task and Ego Orientation in Sport Questionnaire (TEOSQ) and the Intrinsic Motivation Inventory (IMI) were modified slightly to reflect involvement in salsa dancing rather than sport and then were administered to 139 Latin dance students at the beginning and end of an 11-week term. The dance classes were divided into control and intervention groups, balanced in terms of sample size and level of instruction. The intervention group completed a salsa self-reflection form during or after class for 9 weeks. At the posttest all students rated their salsa performance and the intervention group evaluated the self-reflection process. Results indicate that although achievement goal orientations were not affected, structured self-reflection is perceived to be a positive tool and may be a useful technique to enhance perceived performance and maintain effort and perceived importance. The participants’ perceptions of the self-reflection process were positive, with no negative effects of engaging in the process reported.
Rienk M.A. van der Slikke, Annemarie M.H. de Witte, Monique A.M. Berger, Daan J.J. Bregman and Dirk Jan H.E.J. Veeger
In wheelchair sports, athlete and wheelchair form one functional unit determining individual wheelchair mobility performance (WMP). 1 To enhance the performance, athletes could focus on physical progress, technical wheelchair improvement, or optimization of the interaction between both. That
Bryan E. Denham
In this essay, the author proposes that, in order to understand how the issue of performance-enhancing-drug use in professional baseball has been defined for mass audiences, scholars need to consider the political and economic interests of both baseball and the media companies that have covered the issue. Where performance-enhancing drugs are concerned, media characterizations have had a significant impact on the formation of public and organizational policy, and the author seeks to demonstrate that portrayals and perceptions of drug use in baseball can be understood through the media product that results from an intersection of normative standards with powerful influences on those standards. Calling out the heavy hitters in a culture of pervasive drug use is unfair to elite performers in that media reports sometimes give the impression that athletes have reached superstar status because they were willing to do what others were not; this is a basic falsehood.
Emily M. Hartley, Matthew C. Hoch and Robert J. Cramer
physically active populations. Two studies have investigated the use of an educational intervention to improve behavioral determinants and participation within an ERIPP. An educational workshop focused on education regarding ERIPPs and possible strategies to enhance implementation was utilized within coaches
Orlagh Farmer, Donna Duffy, Kevin Cahill, Diarmuid Lester, Sarahjane Belton and Wesley O’Brien
). It is also important to note that OYS participants cumulatively acquire transferable movement skills for enhanced competence and confidence ( Rosewater, 2010 ), all of which are imperative benefits for female youth PA participation. Similar to OYS, fundamental movement skills (FMS) have been shown to
Adam U. Upshaw, Tiffany S. Wong, Arash Bandegan and Peter W.R. Lemon
Postexercise chocolate milk ingestion has been shown to enhance both glycogen resynthesis and subsequent exercise performance. To assess whether nondairy chocolate beverage ingestion post–glycogen-lowering exercise can enhance 20-km cycling time trial performance 4 hr later, eight healthy trained male cyclists (21.8 ± 2.3y, VO2max = 61.2 ± 1.4 ml·kg-1·min-1; M ± SD) completed a series of intense cycling intervals designed to lower muscle glycogen (Jentjens & Jeukendrup, 2003) followed by 4 hr of recovery and a subsequent 20-km cycling time trial. During the first 2 hr of recovery, participants ingested chocolate dairy milk (DAIRYCHOC), chocolate soy beverage (SOYCHOC), chocolate hemp beverage (HEMPCHOC), low-fat dairy milk (MILK), or a low-energy artificially sweetened, flavored beverage (PLACEBO) at 30-min intervals in a double-blind, counterbalanced repeated-measures design. All drinks, except the PLACEBO (247 kJ) were isoenergetic (2,107 kJ), and all chocolate-flavored drinks provided 1-g CHO·kg body mass-1·h-1. Fluid intake across treatments was equalized (2,262 ± 148 ml) by ingesting appropriate quantities of water based on drink intake. The CHO:PRO ratio was 4:1, 1.5:1, 4:1, and 6:1 for DAIRYCHOC, MILK, SOYCHOC, and HEMPCHOC, respectively. One-way analysis of variance with repeated measures showed time trial performance (DAIRYCHOC = 34.58 ± 2.5 min, SOYCHOC = 34.83 ± 2.2 min, HEMPCHOC = 34.88 ± 1.1 min, MILK = 34.47 ± 1.7 min) was enhanced similarly vs PLACEBO (37.85 ± 2.1) for all treatments (p = .019) These data suggest that postexercise macronutrient and total energy intake are more important for same-day 20-km cycling time trial performance after glycogen-lowering exercise than protein type or protein-to-carbohydrate ratio.