Sleep Deprivation and Ultra-endurance Performance: Assessment and Countermeasures

Considered a psychobiological state similar to mental fatigue, sleep deprivation can be defined as a period of extended wakefulness for, at least, 24 hours. Ultra-endurance events are often described as exercise bouts lasting more than six hours, or running distances covered longer than a traditional marathon. The first aim of this thesis was to explore the sleep and performance of athletes in ultra-marathons longer than 161 km (100 mi). A moderate association between sleep duration and race time was found. Before the first sleep episode, athletes remained awake for more than 24 h. Ratings of perceived exertion (RPE), sleep bouts, sleep time, and sleepiness increased over the course of the race, whereas running speed decreased. As a consequence of the psychophysiological demands of ultra-endurance exercise and the exacerbated sleep loss, it has been suggested that perception of effort plays a key role in pace regulation during ultra-marathon events. The second aim was to investigate the use of caffeine as a countermeasure for the detrimental effects of sleep deprivation on endurance performance. After one night of sleep deprivation, 6 mg·kg-1 of caffeine improved 30-min running time trial performance by 5.54%. Caffeine reduces perception of effort, allowing participants to sustain a higher running speed at a lower RPE. Therefore, we propose that caffeine can be used to counteract the negative effects associated with sleep deprivation on endurance performance. The third aim was to study the effects training for a mountain ultra-marathon on sleep deprivation tolerance. Three bouts of exercise after one night of sleep deprivation over a 14-week period did not improve tolerance to the negative effects of sleep deprivation on endurance performance. One night of sleep deprivation reduces time to exhaustion by 28% when running at 75% of peak treadmill speed. Better sleep deprivation tolerance was associated with better chances to finish a ~340-km mountain ultra-marathon race. The main findings presented in this doctoral research thesis are: 1) a moderate positive association between sleep-related parameters and race time, suggesting that faster runners sleep less and spend less time in activities (i.e., restoring food/drinks at the checkpoints, resting, sleeping) other than moving towards the finish line. 2) The use of caffeine as a measure to counteract the negative effects of sleep deprivation on endurance performance. 3) Three exercise bouts in a sleep deprived state over a 14-week period did not reduce the negative effects of sleep deprivation. These findings might be particularly useful for athletes and/or coaches in the field of ultra-marathon and ultra-endurance performance. Sleep assessment during a mountain-ultra marathon and the countermeasures provided might help to plan their races accordingly

Impact of prior accumulated work and intensity on power output in elite/international level road cyclists—a pilot study

Background. This study aimed to investigate the impact of the intensity of prior accumulated work on the decline in power output in elite/international level road cyclists, comparing the effects of prior continuous moderate intensity versus intermittent high intensity cycling.Methods. Nine elite/international level road cyclists (age 26.2 +/- 4.0 years; body mass: 66.6 +/- 5.5 kg; height: 176 +/- 0.4 cm) conducted a 12-min field test (12 min(fresh)) during two consecutive training camps. Participants then performed both a 150-min moderate intensity continuous (MIC) work bout or a 150-min high intensity intermittent (HII) race simulation in randomized order, cross-over design. After each condition a 12-min field test (12 min(fatigue)) was completed.Results. Absolute and relative 12min(fresh) power output were not significantly different between training camps (p>0.05). The 12 min(fatigue) power after HII was significantly lower than 12min(fatigue) after MIC (Delta=14W; p=0.014). Participants recorded more percentage time (%Time) in heart rate (HR) zone 3 (Delta=9.2%; p=0.003) and power output band between 5.0-7.9W.kg(-1) (Delta=8.9%; p=0.002) as well as higher total work (Delta=237 kJ; p <= 0.001) during HII.Conclusion. These findings reveal that the decline in power output is higher after HII compared to MIC cycling work bouts. This suggests that the quantification of total work and intensity should be used in conjunction to predict a distinctive decline in power output. Future research is required to better understand the mechanisms of endurance "durability" in elite/international level road cyclists

The effect of caffeine on cognitive performance is influenced by CYP1A2 but not ADORA2A genotype, yet neither genotype affects exercise performance in healthy adults

Purpose: To determine the influence of two commonly occurring genetic polymorphisms on exercise, cognitive performance, and caffeine metabolism, after caffeine ingestion. Methods: Eighteen adults received caffeine or placebo (3 mg kg−1) in a randomised crossover study, with measures of endurance exercise (15-min cycling time trial; 70-min post-supplementation) and cognitive performance (psychomotor vigilance test; PVT; pre, 50 and 95-min post-supplementation). Serum caffeine and paraxanthine were measured (pre, 30 and 120-min post-supplementation), and polymorphisms in ADORA2A (rs5751876) and CYP1A2 (rs762551) genes analysed.Results: Caffeine enhanced exercise performance (P  0.05). Caffeine enhanced PVT performance (P  0.05). Serum caffeine and paraxanthine responses were not different between genotypes (P > 0.05).Conclusion: Caffeine enhanced CYP1A2 ‘fast’ metabolisers’ cognitive performance more than ‘slow’ metabolisers. No other between-genotype differences emerged for the effect of caffeine on exercise or cognitive performance, or metabolism

Assessing Cognitive-Motor Interference in Military Contexts: Validity and Reliability of Two Dual-tasking Tests

Introduction Cognitive-motor interference is the decrease in cognitive performance and/or physical performance occurring when a cognitive task and a physical task are performed concurrently (dual task) compared to when they are performed in isolation (single task). The aim of this study was to investigate the construct validity and test–retest reliability of two cognitive-motor interference tests in military contexts. Materials and Methods Twenty-two soldiers, officers, and cadets performed a 10-min loaded marching, a 10-min Psychomotor Vigilance Task, and the two tasks combined (visit 1). During visit 2, a 5-min running time trial, a 5-min Word Recall Task, and the two tasks combined. These tests were repeated by 20 participants after 2 weeks (visits 3 and 4). Results Significant impairments were shown on both running distance (P < .001) and number of words recalled (P = .004) in the dual-task condition compared to the single-task condition. Significantly shorter step length (P < .001) and higher step frequency (P < .001) were found during the loaded marching in the dual-task condition compared to the single-task condition. No significant differences were observed in mean reaction time (P = .402) and number of lapses (P = .479) during the Psychomotor Vigilance Task. Good-to-excellent reliability was found for all the cognitive and physical variables in both single- and dual-task conditions, except for the number of lapses. Conclusion These findings suggest that the Running + Word Recall Task test is a valid and reliable dual-tasking test that could be used to assess cognitive-motor interference in military contexts

Bifocal dual reflectarray with curved main surface

This paper presents a novel approach to synthesizing curved reflectarrays using Geometrical Optics (GO). It introduces the concepts of virtual normal and path length shift, which enable a vector-based formulation of the problem that can be solved using ray tracing techniques. The formulation is applied for the design of two different versions of a Dual Bifocal Reflectarray with a parabolic main surface and a flat subreflectarray. The first version aims to enhance the performance of the multibeam antenna by providing a focal ring located at the feed cluster plane. The second version focuses on improving the scanning characteristics of the antenna in the horizontal plane by incorporating two foci. The synthesis procedure yields samples of the path length shift or its derivatives. To reconstruct the phase distribution, an interpolation scheme is employed and described in this paper. Numerical results are presented for both the focal-ring and two-foci configurations, demonstrating the feasibility of this solution for multibeam or scanning satellite antennas operating in the Ka.European Space Research and Technology Centre | Ref. 4000117113/16/NL/AFMinisterio de Economía y Competitividad | Ref. PDC2021-120959-C21/C22Ministerio de Ciencia e Innovación | Ref. RYC2021-033593-IXunta de Galicia | Ref. GRC-ED431C-2019/2

Improving air quality in metropolitan Mexico City : an economic valuation

Mexico City has for years experienced high levels of ozone and particulate air pollution. In 1995-99 the entire population of the Mexico City metropolitan area was exposed to annual average concentrations of fine particulate pollution (particulates with a diameter of less than 10micrometers, or PM10) exceeding 50 micrograms per cubic meter, the annual average standard in both Mexico and the United States. Two million people were exposed to annual average PM10 levels of more than 75 micrograms per cubic meter. The daily maximum one-hour ozone standard was exceeded at least 300 days a year. The Mexico Air Quality Management Team documents population-weighted exposures to ozone and PM10 between 1995 and 1999, project exposures in 2010, and computes the value of four scenarios for 2010: A 10 percent reduction in PM10 and ozone. A 20 percent reduction in PM10 and ozone. Achievement of ambient air quality standards across the metropolitan area. A 68 percent reduction in ozone and a 47 percent reduction in PM10 across the metropolitan area. The authors calculate the health benefits of reducing ozone and PM10 for each scenario using dose-response functions from the peer-reviewed literature. They value cases of morbidity and premature mortality avoided using three approaches: Cost of illness and forgone earnings only (low estimate). Cost of illness, forgone earnings, and willingness to pay for avoided morbidity (central case estimate). Cost of illness, forgone earnings, willingness to pay for avoided morbidity, and willingness to pay for avoided mortality (high estimate). The results suggest that the benefits of a 10 percent reduction in ozone and PM10 in 2010 are about $760 million (in 1999 U.S. dollars) annually in the central case. The benefits of a 20 percent reduction in ozone and PM10 are about$1.49 billion annually. In each case the benefits of reducing ozone amount to about 15 percent of the total benefits. By estimating the magnitude of the benefits from air pollution control, the authors provide motivation for examining specific policies that could achieve the air pollution reductions that they value. They also provide unit values for the benefits from reductions in ambient air pollution (for example, per microgram of PM10) that could be used as inputs into a full cost-benefit analysisof air pollution control strategies.Montreal Protocol,Public Health Promotion,Global Environment Facility,Air Quality&Clean Air,Health Monitoring&Evaluation,Montreal Protocol,Air Quality&Clean Air,Health Monitoring&Evaluation,Global Environment Facility,Transport and Environment

Inactivation of nuclear factor-Y inhibits vascular smooth muscle cell proliferation and neointima formation

OBJECTIVE: Atherosclerosis and restenosis are multifactorial diseases associated with abnormal vascular smooth muscle cell (VSMC) proliferation. Nuclear factor-Y (NF-Y) plays a major role in transcriptional activation of the CYCLIN B1 gene (CCNB1), a key positive regulator of cell proliferation and neointimal thickening. Here, we investigated the role of NF-Y in occlusive vascular disease. APPROACH AND RESULTS: We performed molecular and expression studies in cultured cells, animal models, and human tissues. We find upregulation of NF-Y and cyclin B1 expression in proliferative regions of murine atherosclerotic plaques and mechanically induced lesions, which correlates with higher binding of NF-Y to target sequences in the CCNB1 promoter. NF-YA expression in neointimal lesions is detected in VSMCs, macrophages, and endothelial cells. Platelet-derived growth factor-BB, a main inductor of VSMC growth and neointima development, induces the recruitment of NF-Y to the CCNB1 promoter and augments both CCNB1 mRNA expression and cell proliferation through extracellular signal-regulated kinase 1/2 and Akt activation in rat and human VSMCs. Moreover, adenovirus-mediated overexpression of a NF-YA-dominant negative mutant inhibits platelet-derived growth factor-BB-induced CCNB1 expression and VSMC proliferation in vitro and neointimal lesion formation in a mouse model of femoral artery injury. We also detect NF-Y expression and DNA-binding activity in human neointimal lesions. CONCLUSIONS: Our results identify NF-Y as a key downstream effector of the platelet-derived growth factor-BB-dependent mitogenic pathway that is activated in experimental and human vasculoproliferative diseases. They also identify NF-Y inhibition as a novel and attractive strategy for the local treatment of neointimal formation induced by vessel denudation.This study was funded by the Spanish Ministry of Economy and Competiveness (MINECO; grants SAF2010-16044, SAF200911949), Instituto de Salud Carlos III (ISCIII; grants RD12/0042/0021, RD12/0042/0028, RD12/0042/0053), and the Dr Léon Dumont Prize 2010 by the Belgian Society of Cardiology (to Vicente Andrés). Patricia Fernández received salary support from ISCIII and Carlos Silvestre-Roig from Fundación Mario Losantos del Campo and Fundación Ferrer para la Investigación. Óscar M. Pello and Ricardo Rodríguez-Calvo hold a Juan de la Cierva contract from MINECO. Vanesa Esteban is an investigator of the Sara Borell program from ISCIII (CD06/00232). The Centro Nacional de Investigaciones Cardiovasculares (CNIC) is supported by MINECO and Pro-CNIC Foundation.S