Experimental sleep restriction (SR) has demonstrated reduced insulin sensitivity in healthy individuals. Exercise is well-known to be beneficial for metabolic health. A single bout of exercise has the capacity to increase insulin sensitivity for up to 2 days. Therefore, the current study aimed to determine if sprint interval exercise could attenuate the impairment in insulin sensitivity after one night of SR in healthy males. Nineteen males were recruited for this randomized crossover study which consisted of four conditions—control, SR, control plus exercise, and sleep restriction plus exercise. Time in bed was 8 hr (2300–0700) in the control conditions and 4 hr (0300–0700) in the SR conditions. Conditions were separated by a 1-week entraining period. Participants slept at home, and compliance was assessed using wrist actigraphy. Following the night of experimental sleep, participants either conducted sprint interval exercise or rested for the equivalent duration. An oral glucose tolerance test was then conducted. Blood samples were obtained at regular intervals for measurement of glucose and insulin. Insulin concentrations were higher in SR than control (p = .022). Late-phase insulin area under the curve was significantly lower in sleep restriction plus exercise than SR (862 ± 589 and 1,267 ± 558; p = .004). Glucose area under the curve was not different between conditions (p = .207). These findings suggest that exercise improves the late postprandial response following a single night of SR.
Emma L. Sweeney, Daniel J. Peart, Irene Kyza, Thomas Harkes, Jason G. Ellis and Ian H. Walshe
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.
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.
Michal Botek, Jakub Krejčí, Andrew J. McKune and Barbora Sládečková
Purpose: Hydrogen-rich water (HRW) has been shown to have an antifatigue effect. This study assessed up-hill running performance, as well as physiological and perceptual responses after supplementation with 1680 mL HRW between 24 h and 40 min before running, in athletes of heterogeneous running ability. Methods: Sixteen males (mean [SD] age 31.6 [8.6] y, VO2max 57.2 [8.9] mL·kg−1·min−1, body fat 13.4% [4.4%]) participated in this study. Using a randomized, double-blind, placebo-controlled crossover design, participants consumed either HRW or placebo prior to performing two 4.2-km up-hill races separated by a week. Race time (RT), average race heart rate, and immediately postrace rating of perceived exertion were assessed. Results: After analysis of data for all runners, HRW effect was unclear (−10 to 7 s, 90% confidence interval) for RT, likely trivial for heart rate (−2 to 3 beats·min−1), and likely trivial for postrace rating of perceived exertion (−0.1 to 1.0). A possible negative correlation was found between RT differences and average RT (r = −.79 to −.15). HRW for the 4 slowest runners (RT = 1490  s) likely improved the RT (−36 to −3 s), whereas for the 4 fastest runners (RT = 1069  s) the performance effect of HRW was unclear (−10 to 26 s). Conclusions: HRW intake had an unclear antifatigue effect on performance in terms of mean group values. However, it appears that the magnitude of the antifatigue effect of HRW on performance depends on individual running ability.
Nicole C.A. Strock, Kristen J. Koltun, Emily A. Southmayd, Nancy I. Williams and Mary Jane De Souza
Energy deficiency in exercising women can lead to physiological consequences. No gold standard exists to accurately estimate energy deficiency, but measured-to-predicted resting metabolic rate (RMR) ratio has been used to categorize women as energy deficient. The purpose of the study was to (a) evaluate the accuracy of RMR prediction methods, (b) determine the relationships with physiological consequences of energy deficiency, and (c) evaluate ratio thresholds in a cross-sectional comparison of ovulatory, amenorrheic, or subclinical menstrual disturbances in exercising women (n = 217). Dual-energy X-ray absorptiometry (DXA) and indirect calorimetry provided data on anthropometrics and energy expenditure. Harris–Benedict, DXA, and Cunningham (1980 and 1991) equations were used to estimate RMR and RMR ratio. Group differences were assessed (analysis of variance and Kruskal–Wallis tests); logistic regression and Spearman correlations related ratios with consequences of energy deficiency (i.e., low total triiodothyronine; TT3). Sensitivity and specificity calculations evaluated ratio thresholds. Amenorrheic women had lower RMR (p < .05), DXA ratio (p < .01), Cunningham1980 (p < .05) and Cunningham1991 (p < .05) ratio, and TT3 (p < .01) compared with the ovulatory group. Each prediction equation overestimated measured RMR (p < .001), but predicted (p < .001) and positively correlated with TT3 (r = .329–.453). A 0.90 ratio threshold yielded highest sensitivity for Cunningham1980 (0.90) and Harris–Benedict (0.87) methods, but a higher ratio threshold was best for DXA (0.94) and Cunningham1991 (0.92) methods to yield a sensitivity of 0.80. In conclusion, each ratio predicted and correlated with TT3, supporting the use of RMR ratio as an alternative assessment of energetic status in exercising women. However, a 0.90 ratio cutoff is not universal across RMR estimation methods.
Carlos Capella-Peris, Jesús Gil-Gómez and Òscar Chiva-Bartoll
Purpose: To compare the development of teaching competency in preservice teachers of physical education (n = 96) through two different modalities of intervention from the same service-learning program. The preservice teachers provided a direct service to children with motor functional diversity, promoting their motor skills and counteracting their lack of social attention. Method: The topic was approached using mixed methods with methodological triangulation. Quantitative evidence was gathered through a quasi-experimental design of two nonequivalent experimental groups implementing the following instrument: the Teaching Competency while performing Motor Skills and Body Language Games Rubric. Meanwhile, qualitative analysis was undertaken by elaborating upon 12 life histories of multiple crossed stories. Results: The quantitative results provided significant evidence regarding the academic effect of service-learning on preservice teachers, while the qualitative interpretation complemented this view, reflecting on how this learning was developed. Discussion/Conclusion: The authors provided the original findings of the service-learning effects on the teaching competency of preservice teachers as well as the promotion of additional academic and social learning.