Relationships between training load, sleep duration, and daily wellbeing and recovery measures in youth athletes

Purpose: To assess the relationships between training load, sleep duration and three daily wellbeing, recovery and fatigue measures in youth athletes. Methods: Fifty-two youth athletes completed three maximal countermovement jumps (CMJ), a daily wellbeing questionnaire (DWB), the Perceived Recovery Status scale (PRS), and provided details on their previous day's training loads (training) and self-reported sleep duration (sleep) on four weekdays over a seven week period. Partial correlations, linear mixed models and magnitude-based inferences were used to assess the relationships between the predictor variables (training; sleep) and the dependent variables (CMJ; DWB; PRS). Results: There was no relationship between CMJ and training (r=-0.09; ±0.06) or sleep (r=0.01; ±0.06). The DWB was correlated with sleep (r=0.28; ±0.05, small), but not training (r=-0.05; ±0.06). The PRS was correlated with training (r=-0.23; ±0.05, small), but not sleep (r=0.12; ±0.06). The DWB was sensitive to low sleep(d=-0.33; ±0.11) relative to moderate, PRS was sensitive to high (d=-0.36; ±0.11) and low (d=0.29; ±0.17) training relative to moderate. Conclusions: The PRS is a simple tool to monitor the training response, but DWB may provide a greater understanding of the athlete's overall wellbeing. The CMJ was not associated with the training or sleep response in this population

Strength and conditioning in schools: a strategy to optimise health, fitness and physical activity in youths

Editoria

The within-participant Correlation between s-RPE and Heart Rate in Youth Sport

The monitoring of training load is important to ensure athletes are adapting optimally to a training stimulus. Before quanti ca- tion of training load can take place, coaches must be con dent that the tools available are accurate. We aimed to quantify the within-participant correlation between the session rating of perceived exertion (s-RPE) and summated heart rate zone (sHRz) methods of monitoring internal training load. Training load (s-RPE and heart rate) data were collected for rugby, soc- cer and eld hockey eld-based training sessions over a 14- week in-season period. A total of 397 sessions were monitored (rugby n = 170, soccer n = 114 and eld hockey n = 113). With- in-subject correlations between s-RPE and sHRz were quanti- ed for each sport using a general linear model. Large correla- tions between s-RPE and the sHRz method were found for rugby (r = 0.68; 95 % CI 0.59–0.75) and eld hockey (r = 0.60; 95 % CI 0.47–0.71) with a very large correlation found for soccer (r = 0.72; 95 % CI 0.62–0.80). No signi cant di erences were found between the correlations for each sport. The very large and large correlations found between s-RPE and the sHRz meth- ods support the use of s-RPE in quantifying internal training load in youth sport

Movement and Physiological Demands of Australasian National Rugby League Referees.

Purpose: To evaluate the movement and physiological demands of the Australasian National Rugby League (NRL) referees, officiating with a ‘two referee’ (i.e., ‘lead’ and ‘pocket’) system and to compare the demands of the lead referee and pocket referees. Methods: 10 Hz global positioning system devices were used to obtain 86 data sets (‘lead’, n=41; ‘pocket’, n=45) on 19 NRL referees. Total distance, relative distance covered and heart rate per half and across match-play was examined within and between referees using t-tests. Distance, time and number of movement 'efforts' were examined in six velocity classifications (i.e., standing 7.0 m.s-1) using ANOVA. Cohen's d effect sizes were reported. Results: There were no significant differences between the ‘lead’ and ‘pocket’ referee for any movement or physiological variable. There was an overall significant (large; very large) effect for distance (% distance) and time (% time) (P 5.51 m.s-1. Conclusions: Findings highlight the intermittent nature of rugby league refereeing, but show that there were no differences in the movement and physiological demands of the two refereeing roles. Findings are valuable for those responsible for the preparation, training and conditioning of NRL referees, and to ensure training prepares for and simulates match demands

Financing Constraints, Firm Dynamics, and International Trade

This paper studies the impact of financial constraints on exporter dynamics, and the role of financial intermediation in international trade. We propose a two-country general equilibrium model economy in which entrepreneurs and lenders engage in long-term credit relationships. Financial markets are endogenously incomplete because of private information, and financial constraints arise as a consequence of optimal financial contracts. In equilibrium, competitive financial intermediaries actively channel individuals' short-term deposits to fund a diversified portfolio of long-term risky firms. Young and small firms operate below their efficient level, and their financial constraint is relaxed as the entrepreneur's claim to future cash-flows increases. Consistent with empirical regularities, there is a substantial year-to-year transition in and out of export markets for smaller firms, and new exporters account only for a small share of total exports. Established exporters are less likely to exit export markets and tend to experience slower, albeit more stable growth

Histiocytoid cardiomyopathy and microphthalmia with linear skin defects syndrome: phenotypes linked by truncating variants in NDUFB11

Variants in NDUFB11, which encodes a structural component of complex I of the mitochondrial respiratory chain (MRC), were recently independently reported to cause histiocytoid cardiomyopathy (histiocytoid CM) and microphthalmia with linear skin defects syndrome (MLS syndrome). Here we report an additional case of histiocytoid CM, which carries a de novo nonsense variant in NDUFB11 (ENST00000276062.8: c.262C > T; p.[Arg88*]) identified using whole-exome sequencing (WES) of a family trio. An identical variant has been previously reported in association with MLS syndrome. The case we describe here lacked the diagnostic features of MLS syndrome, but a detailed clinical comparison of the two cases revealed significant phenotypic overlap. Heterozygous variants in HCCS (which encodes an important mitochondrially targeted protein) and COX7B, which, like NDUFB11, encodes a protein of the MRC, have also previously been identified in MLS syndrome including a case with features of both MLS syndrome and histiocytoid CM. However, a systematic review of WES data from previously published histiocytoid CM cases, alongside four additional cases presented here for the first time, did not identify any variants in these genes. We conclude that NDUFB11 variants play a role in the pathogenesis of both histiocytoid CM and MLS and that these disorders are allelic (genetically related)