Search results for "Fatigue"

2015

It has been shown that the mental fatigue induced by prolonged self-regulation increases perception of effort and reduces performance during subsequent endurance exercise. However, the physiological mechanisms underlying these negative effects of mental fatigue are unclear. The primary aim of this study was to test the hypothesis that mental fatigue exacerbates central fatigue induced by whole-body endurance exercise. Twelve subjects performed 30 min of either an incongruent Stroop task to induce a condition of mental fatigue or a congruent Stroop task (control condition) in a random and counterbalanced order. Both cognitive tasks (CTs) were followed by a whole-body endurance task (ET) cons…

Regulation of Endurance Performance: New Frontiers

2017

Successful endurance performance requires the integration of multiple physiological and psychological systems, working together to regulate exercise intensity in a way that will reduce time taken or increase work done. The systems that ultimately limit performance of the task are hotly contested, and may depend on a variety of factors including the type of task, the environment, external influences, training status of the individual and a host of psychological constructs. These factors can be studied in isolation, or inclusively as a whole-body or integrative system. A reductionist approach has traditionally been favoured, leading to a greater understanding and emphasis on muscle and cardio…

Stretch-shortening cycle: a powerful model to study normal and fatigued muscle.

2000

Stretch-shortening cycle (SSC) in human skeletal muscle gives unique possibilities to study normal and fatigued muscle function. The in vivo force measurement systems, buckle transducer technique and optic fiber technique, have revealed that, as compared to a pure concentric action, a non-fatiguing SSC exercise demonstrates considerable performance enhancement with increased force at a given shortening velocity. Characteristic to this phenomenon is very low EMG-activity in the concentric phase of the cycle, but a very pronounced contribution of the short-latency stretch-reflex component. This reflex contributes significantly to force generation during the transition (stretch-shortening) pha…

Early rehabilitation of cancer patients - a randomized controlled intervention study.

2013

Published version of an article in the journal: BMC Cancer. Also available from the publisher at: http://dx.doi.org/10.1186/1471-2407-13-9 Open access Background: Faced with a life-threatening illness, such as cancer, many patients develop stress symptoms, i.e. avoidance behaviour, intrusive thoughts and worry. Stress management interventions have proven to be effective; however, they are mostly performed in group settings and it is commonly breast cancer patients who are studied. We hereby present the design of a randomized controlled trial (RCT) evaluating the effectiveness and cost-effectiveness of an individual stress-management intervention with a stepped-care approach in several cance…

Risk based Fatigue Inspection Planning – State of the Art

2013

AbstractThe present paper presents the methodology and the practical calculations for risk based inspection planning of fatigue cracks in welded offshore steel structures. Due to the uncertainty in the variables involved in the problem the planning has to be carried out by stochastic modeling and risk based assessments. Scatter in potential crack growth has to be analyzed by applied probabilistic facture mechanics and the uncertainty in the performance of the actual inspection technique has to be determined. With given risk acceptance criteria the practical outcome of the analyses is recommended inspection techniques and associated planned inspection time intervals. The classical theory is …

Vibration effect on ball score test in international vs. national level table tennis

2018

In table tennis, motor skills are crucial for discriminating player level. However, there is a dearth of studies exploring the impact of a vibrational stimulus on performance. Thirty-four male players (age 25 +/- 2 years ; body mass index, BMI 23.4 +/- 1.2 kg.m(-2)) participated in the study. Seventeen played at international level (IL), while the remaining 17 played at national level (NL). The participants underwent a ball-handling test, the ball score, before (PRE) and after (POST) a vibrational stimulus. Intra-class correlation (ICC) for the ball score result showed good reliability (ICC 0.87 for IL and 0.80 for NL). Repeated measures ANOVA showed differences between groups for ball scor…

Stochastic Fatigue Models for Efficient Planning Inspections in Service of Aircraft Structures

2008

For important fatigue-sensitive structures of aircraft whose breakdowns cause serious accidents, it is required to keep their reliability extremely high. In this paper, we discuss inspection strategies for such important structures against fatigue failure. The focus is on the case when there are fatiguecracks unexpectedly detected in a fleet of aircraft within a warranty period (prior to the first inspection). The paper examines this case and proposes stochastic models for prediction of fatigue-crack growth to determine appropriate inspections intervals. We also do not assume known parameters of the underlying distributions, and the estimation of that is incorporated into the analysis and d…

Inspection Policies in Service of Fatigued Aircraft Structures

2011

Fatigue is one of the most important problems of aircraft arising from their nature as multiple-component structures, subjected to random dynamic loads. For guaranteeing safety, the structural life ceiling limits of the fleet aircraft are defined from three distinct approaches: Safe-Life, Fail-Safe, and Damage Tolerance approaches. The common objectives to define fleet aircraft lives by the three approaches are to ensure safety while at the same time reducing total ownership costs. In this paper, the damage tolerance approach is considered and the focus is on the inspection scheme with decreasing intervals between inspections. The paper proposes an analysis methodology to determine appropri…

MULTIPLE SCLEROSIS: PHYSICAL ACTIVITY AND WELL-BEING

2017

Multiple sclerosis (MS) is a chronic disease that affects central nervous system (CNS) – coexists in brain, spinal cord and optic nerves. It can process in three different courses: remitting, progressive and progressive-relapsing. Although there is still no cure for MS, effective strategies are available to modify the disease course, reduce number of relapses, rate of progressions and development of new lesions. Nowadays, moderate physical performance is strongly recommended: besides having positive effects on the body, it can have a positive effect on the psychophysical wellbeing. Essentially there are 3 types of training protocols: aerobic (endurance training), strength training (resistan…

Performance improvements of asphalt mixtures by dry addition of polymeric additives

2017

This paper shows the results of an experimental study concerning the development and optimization of asphalt mixtures for binder and base courses, improved with specifically engineered additives. The focus was on the mechanical improvements of the mixtures as achievable via dry modification with polymeric additives by making use of aggregate and bitumen of average quality, as locally available, in order to limit the consumption of virgin materials. The results allowed interesting conclusions to be drawn about the use of polymeric additives for these mixtures. In particular, the modified mixtures proved to have better performance in terms of both permanent deformation resistance and stiffnes…