Search results for "Fatigue."
showing 10 items of 621 documents
Muscle function in monozygotic female twin pairs discordant for hormone replacement therapy
2011
Introduction: Postmenopausal monozygotic twin pairs discordant for hormone replacement therapy (HRT) provide an advantageous study design controlling for genetic background for elucidating the relationships between aging, sex hormone levels, muscle strength, contractile capacity, and fatigability. Methods: Thirteen postmenopausal monozygotic twin pairs discordant for HRT were measured for maximal voluntary torque (MVC) and twitch characteristics using electrical stimulation before and after intermittent dynamic plantarflexor exercise until exhaustion. Results: Peak twitch torque was 32% higher in HRT users than in their non-HRT, genetically identical sisters (P = 0.002), but MVC did not dif…
Acute neuromuscular and endocrine responses and recovery to single session combined endurance and strength loadings: ‘Order effect’ in untrained youn…
2013
The purpose of this study was to investigate acute neuromuscular and endocrine responses and recovery to a single session of combined endurance and strength loading using two loading orders. Forty-two men were demographically matched to perform a single session of combined endurance+strength (E+S) or strength+endurance (S+E) loading. The strength loading was conducted on a leg press and included sets of power, maximal strength and hypertrophic loads with an overall duration of 30 minutes. The endurance loading was conducted on a bike ergometer and performed by continuous cycling over 30min at 65% of subject’s individual maximal Watts. Both loading conditions led to significant acute reducti…
Un estudio piloto sobre el efecto diferencial de la fatiga por conducción en personas mayores
2011
Hay indicios de que la fatiga, uno de los principales efectos de la conducción prolongada, es más notable en mayores. El presente artículo recoge un estudio sobre el efecto de la conducción prolongada utilizando un simulador, en un grupo de sujetos mayores de 55 años. Los sujetos fueron evaluados médica y psicológicamente antes y después de la prueba de conducción. Se aplicaron las pruebas médicas de tensión arterial, pulso y saturación de oxígeno en sangre y como prueba psicológica, el Driver-Test. Resultados preliminares indican que existe una disminución del rendimiento después de conducir, afectando especialmente a la capacidad de toma de decisiones. Some evidences show that fatigue, th…
Influencia de la fatiga en la calidad de movimiento de personas con lesión medular
2017
La fatiga es un fenómeno fisiológico complejo por el que se limita la capacidad del individuo para mantener una actividad física concreta (Bigland-Ritchie y Woods, 1984). En individuos sanos el desarrollo de la fatiga está ligado al ejercicio físico siendo la causa principal que limita la duración del mismo. Además, la fatiga aparece como parte de la patología de diferentes enfermedades y su efecto es igualmente limitador de la actividad física. El estudio de un fenómeno tan complejo se ha realizado con distintos abordajes experimentales y en distintos niveles fisiológicos con individuos sanos, lo que ha permitido distinguir tres tipos básicos de fatiga: a) fatiga periférica, producida en e…
Effects of military training on plasma amino acid concentrations and their associations with overreaching.
2020
Amino acids are thought to have a key role in the processes contributing to overreaching development through their metabolic properties and neuronal functions. In the present study, the effects of 10-week military training on the concentrations of 19 amino acids were investigated. Plasma amino acid concentrations were measured at rest from 53 healthy male conscripts on weeks 1, 4, 7, and 9 of their military service. Conscripts were classified as overreached and non-overreached. Overreaching classification was based on fulfilling at least three of five criteria: greater than 5% decrease in maximal oxygen uptake, increased rating perceived exertion (RPE), and decreased lactate-RPE ratio in s…
Fatigue while driving in a car simulator : effects on vigilance performance and autonomic skin conductance
2010
In this vigilance research the effect of fatigue on driver’s voluntary reaction times (RT) and autonomic skin conductance (SC) was studied. Participants (n=17) drove approximately 3 hours in a simulator responding simultaneously on a peripheral visual vigilance task (PVVT). RTs were classified into 5 quintiles according to their latency. Also misses and misclassifications were explored. Results indicated that RTs increased linearly over time. SC amplitudes differed significantly between RT quintiles. Vigilance performance was the best when arousals were frequent but their magnitude remained relatively low. Frequent and high amplitude arousals in turn were associated with the worst performan…
Fatigue-Related and Timescale-Dependent Changes in Individual Movement Patterns Identified Using Support Vector Machine
2020
The scientific and practical fields—especially high-performance sports—increasingly request a stronger focus be placed on individual athletes in human movement science research. Machine learning methods have shown efficacy in this context by identifying the unique movement patterns of individuals and distinguishing their intra-individual changes over time. The objective of this investigation is to analyze biomechanically described movement patterns during the fatigue-related accumulation process within a single training session of a high number of repeated executions of a ballistic sports movement—specifically, the frontal foot kick (mae-geri) in karate—in expert athletes. The two leading r…
Simulation of Fatigue Delamination Growth in Composites with Different Mode Mixtures
2007
A numerical model, obtained by implementing a cyclic damage model in the framework of an interface element, is here proposed to reproduce the crack growth in laminated composites subjected to cyclically repeated loads. This model, which differs from the few studies in the literature on the topic, applies not only to single fracture modes but also to mixed modes, and to constant or variable crack growth rates. The applied load (in terms of force or displacement) is assumed to oscillate between a minimum and a maximum constant value. The Paris curve can be reproduced with accuracy once some parameters in the numerical model are tuned with experiments. These parameters are preliminarily found…
Acute HIT session induced changes and recovery in muscle activation level, voluntary force production and jump performance during 8 weeks of HIT trai…
2017
High-intensity interval training (HIT) has gained wide popularity among competitive athletes and sport enthusiasts in the recent decades. While an extensive amount of research has been done on acute neuromuscular (NM) response and recovery after low-moderate intensity endurance training, the data regarding HIT in recreational athletes remains to be limited. In order to reduce that gap, the present study investigated the acute HIT session induced changes and recovery in muscle activation level, voluntary force production and counter movement jump performance during 8 weeks of HIT training in recreationally endurance trained men. A total of 9 subjects age 30.7 years (± 5.8), participated in t…
Effects of operational assessment of the 4:4 and 4:4/6:6 watch systems on sleepiness, fatigue, and stress responses during patrolling on a navy missi…
2022
The operation of naval vessels involves watchkeeping 24 h per day, which is globally carried out by a variety of different watch systems. In this study, the rotating 4:4 and fixed 4:4/6:6 two-section watch systems were compared in terms of sleepiness, fatigue, and stress responses. The data collection took place on a Finnish Defence Forces' (FDF) Navy missile patrol boat with 15 crew members serving as study participants. The data collection periods lasted two separate weeks (7 days, 6 nights) with the different watch systems. The subjective sleepiness of the participants was assessed before and after every watch using the Karolinska Sleepiness Scale (KSS). Stress responses were assessed da…