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Ibai Garcia-Tabar, Aitor Iturricastillo, Julen Castellano, Eduardo L. Cadore, Mikel Izquierdo, and Igor Setuain

Purpose: To develop gender-specific operational equations for prediction of cardiorespiratory fitness in female footballers. Method: Forty-eight semiprofessional female footballers performed an intermittent progressive maximal running test for determination of fixed blood lactate concentration (FBLC) thresholds. Relationships between FBLC thresholds and the physiological responses to submaximal running were examined. Developed equations (n = 48) were compared with equations previously obtained in another investigation performed in males (n = 100). Results: Submaximal velocity associated with 90% maximal heart rate was related to FBLC thresholds (r = .76 to .79; P < .001). Predictive power (R 2 = .82 to .94) of a single blood lactate concentration (BLC) sample measured at 10 or 11.5 km·h−1 was very high. A single BLC sample taken after a 5-minute running bout at 8.5 km·h−1 was related to FBLC thresholds (r = −.71; P < .001). No difference (P = .15) in the regression lines predicting FBLC thresholds from velocity associated with 90% maximal heart rate was observed between the female and male cohorts. However, regressions estimating FBLC thresholds by a single BLC sample were different (P = .002). Conclusions: Velocity associated with 90% maximal heart rate was robustly related to FBLC thresholds and might serve for mass field testing independently of sex. BLC equations accurately predicted FBLC thresholds. However, these equations are gender-specific. This is the first study reporting operational equations to estimate the FBLC thresholds in female footballers. The use of these equations reduces the burden associated with cardiorespiratory testing. Further cross-validation studies are warranted to validate the proposed equations and establish them for mass field testing.

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Shona L. Halson, Renee N. Appaneal, Marijke Welvaert, Nirav Maniar, and Michael K. Drew

Purpose: Psychological stress is reported to be an important contributor to reduced sleep quality and quantity observed in elite athletes. The purpose of this study was to explore the association between psychological stress and sleep and to identify if specific aspects of sleep are disturbed. Methods: One hundred thirty-one elite athletes (mean [SD], male: n = 46, age 25.8 [4.1] y; female: n = 85, age 24.3 [3.9] y) from a range of sports completed a series of questionnaires in a 1-month period approximately 4 months before the 2016 Rio Olympic Games. Questionnaires included the Pittsburgh Sleep Quality Index; Recovery-Stress Questionnaire; Depression, Anxiety, and Stress Scale (DASS 21); and Perceived Stress Scale (PSS). Results: Regression analysis identified the PSS and DASS stress as the main variables associated with sleep. A PSS score of 6.5 or higher was associated with poor sleep. In addition, a PSS score lower than 6.5 combined with a DASS stress score higher than 4.5 was also associated with poor sleep. Univariate analyses on subcomponents of the Pittsburgh Sleep Quality Index confirmed that PSS is associated with lower sleep quality (t 99 = 2.40, P = .018), increased sleep disturbances (t 99 = 3.37, P = .001), and increased daytime dysfunction (t 99 = 2.93, P = .004). DASS stress was associated with increased sleep latency (t 94 = 2.73, P = .008), increased sleep disturbances (t 94 = 2.25, P = .027), and increased daytime dysfunction (t 94 = 3.58, P = .001). Conclusions: A higher stress state and higher perceived stress were associated with poorer sleep, in particular increased sleep disturbances and increased daytime dysfunction. Data suggest that relatively low levels of psychological stress are associated with poor sleep in elite athletes.

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ZáNean McClain, Erin Snapp, Daniel W. Tindall, and Jill Anderson

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Mark Partington, Jimmy O’Gorman, Kenny Greenough, and Ed Cope

Little is known about the development of coach developers despite their importance in supporting coach learning. In response, this study explored the theories in practice of 23 English coach developers who undertook a continuing professional development course. The data were collected through semistructured interviews, focus groups, and observations of coach developers’ practice and engagement on the course. The data were analysed using a phronetic-iterative approach, with Argyris and Schön’s ideas on theories in practice, mostly espoused theories and theories-in-use, providing the primary heuristic framework. The findings identified how, before the continuing professional development course, the coach developers articulated espoused theories, but as the course progressed, there was a move to theories-in-use. This was due to their (re)constructed understanding of learning and the working environment. The findings are discussed in light of how the continuing professional development course, and tutors’ pedagogic approaches, influenced the coach developers’ knowledge and understanding. Based on these findings, it seems there is much to gain from supporting coach developers with a deconstruction and reconstruction of theories in practice.

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Stephanie Beni, Tim Fletcher, and Déirdre Ní Chróinín

Purpose: The purposes of this research were to design a professional development (PD) initiative to introduce teachers to a pedagogical innovation—the Meaningful Physical Education (PE) approach—and to understand their experiences of the PD process. Method: Twelve PE teachers in Canada engaged in an ongoing PD initiative, designed around characteristics of effective PD, across two school years as they learned about and implemented Meaningful PE. Qualitative data were collected and analyzed. Findings: This research showed that teachers valued a community of practice and modeling when learning to implement Meaningful PE. While teachers were mostly favorable to the PD design, there were several tensions between ideal and realistic forms of PD. Discussion: This research offers support for several characteristics of effective PD to support teachers’ implementation of a novel pedagogical approach and highlights the need to balance tensions in providing forms of PD that are both effective and practical.

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Matthew Andrew, Paul R. Ford, Matthew T. Miller, Allistair P. McRobert, Nathan C. Foster, Guido Seerden, Martin Littlewood, and Spencer J. Hayes

We examined whether practice activities adopted by professional youth soccer coaches are modulated through the implementation of and engagement with cocreative evidence-based programs. Across two experiments, we used systematic observation to identify the practice activities of seven coaches across 134 sessions. In Experiment A, drill-based and games-based activities were recorded and quantified. To encourage behaviour change across the study, the systematic observation data were compared with skill acquisition literature to provide coaches with quantitative feedback and recommendations during workshops. Postworkshop systematic observation data indicated that practice activities used by coaches changed in accordance with the evidenced-based information (increase in games-based activities) delivered within the workshop. Interview data indicated that coaches typically stated that the workshop was a key reason for behaviour change. In a follow-up Experiment B, feedback and recommendations were delivered using an interactive video-based workshop. The systematic observation data indicated that coaches increased the use of soccer activities that contained active decision making with coaches citing the workshop as a key reason for behaviour change. These findings indicate that coaching practice activities can be supported and shaped through the implementation of cocreated workshops wherein coaches collaborate with sport scientists and researchers to bridge the gap between science and application.

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Michael H. Haischer, John Krzyszkowski, Stuart Roche, and Kristof Kipp

Maximal strength is important for the performance of dynamic athletic activities, such as countermovement jumps (CMJ). Although measures of maximal strength appear related to discrete CMJ variables, such as peak ground reaction forces (GRF) and center-of-mass (COM) velocity, knowledge about the association between strength and the time series patterns during CMJ will help characterize changes that can be expected in dynamic movement with changes in maximal strength. Purpose: To investigate the associations between maximal strength and GRF and COM velocity patterns during CMJ. Methods: Nineteen female college lacrosse players performed 3 maximal-effort CMJs and isometric midthigh pull. GRF and COM velocity time series data from the CMJ were time normalized and used as inputs to principal-components analyses. Associations between isometric midthigh pull peak force and CMJ principal-component scores were investigated with a correlational analysis. Results: Isometric midthigh pull peak force was associated with several GRF and COM velocity patterns. Correlations indicated that stronger players exhibited a GRF pattern characterized by greater eccentric-phase rate of force development, greater peak GRF, and a unimodal GRF profile (P = .016). Furthermore, stronger athletes exhibited a COM velocity pattern characterized by higher velocities during the concentric phase (P = .004). Conclusions: Maximal strength is correlated to specific GRF and COM velocity patterns during CMJ in female college lacrosse athletes. Since maximal strength was not correlated with discrete CMJ variables, the patterns extracted via principal-components analyses may provide information that is more beneficial for performance coaches and researchers.

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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.

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Thomas Birkedal Stenqvist, Anna Katarina Melin, Ina Garthe, Gary Slater, Gøran Paulsen, Juma Iraki, Jose Areta, and Monica Klungland Torstveit

The syndrome of Relative Energy Deficiency in Sport (RED-S) includes wide-ranging effects on physiological and psychological functioning, performance, and general health. However, RED-S is understudied among male athletes at the highest performance levels. This cross-sectional study aimed to investigate surrogate RED-S markers prevalence in Norwegian male Olympic-level athletes. Athletes (n = 44) aged 24.7 ± 3.8 years, body mass 81.3 ± 15.9 kg, body fat 13.7% ± 5.8%, and training volume 76.1 ± 22.9 hr/month were included. Assessed parameters included resting metabolic rate (RMR), body composition, and bone mineral density by dual-energy X-ray absorptiometry and venous blood variables (testosterone, free triiodothyronine, cortisol, and lipids). Seven athletes (16%) grouped by the presence of low RMR (RMRratio < 0.90) (0.81 ± 0.07 vs. 1.04 ± 0.09, p < .001, effect size 2.6), also showed lower testosterone (12.9 ± 5.3 vs. 19.0 ± 5.3 nmol/L, p = .020) than in normal RMR group. In low RMRratio individuals, prevalence of other RED-S markers (—subclinical—low testosterone, low free triiodothyronine, high cortisol, and elevated low-density lipoprotein) was (N/number of markers): 2/0, 2/1, 2/2, 1/3. Low bone mineral density (z-score < −1) was found in 16% of the athletes, all with normal RMR. Subclinical low testosterone and free triiodothyronine levels were found in nine (25%) and two (5%) athletes, respectively. Subclinical high cortisol was found in 23% of athletes while 34% had elevated low-density lipoprotein cholesterol levels. Seven of 12 athletes with two or more RED-S markers had normal RMR. In conclusion, this study found that multiple RED-S markers also exist in male Olympic-level athletes. This highlights the importance of regular screening of male elite athletes, to ensure early detection and treatment of RED-S.

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James C. Morehen, Carl Langan-Evans, Elliot C.R. Hall, Graeme L. Close, and James P. Morton

Weight cycling is thought to increase the risk of obesity and cardiometabolic disease in nonathletic and athletic populations. However, the magnitude and frequency of weight cycling is not well characterized in elite athletes. To this end, we quantified the weight cycling practices of a male World Champion professional boxer competing at super middleweight (76.2 kg). Over a 5-year period comprising 11 contests, we assessed changes in body mass (n = 8 contests) and body composition (n = 6 contests) during the training camp preceding each contest. Time taken to make weight was 11 ± 4 weeks (range: 4–16). Absolute and relative weight loss for each contest was 12.4 ± 2.1 kg (range: 9.8–17.0) and 13.9% ± 2.0% (range: 11.3–18.2), respectively. Notably, the athlete commenced each training camp with progressive increases in fat mass (i.e., 12.5 and 16.1 kg for Contests 1 and 11) and reductions in fat-free mass (i.e., 69.8 and 67.5 kg for Contests 1 and 11, respectively). Data suggest that weight cycling may lead to “fat overshooting” and further weight gain in later life. Larger scale studies are now required to characterize the weight cycling practices of elite athletes and robustly assess future cardiometabolic disease risk. From an ethical perspective, practitioners should be aware of the potential health consequences associated with weight cycling.