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A 38-year-old woman presented to the emergency department because of increasing fatigue and shortness of breath, worsening during the past 2 months. At the time of presentation, even minimal exertion [...]

Background. Elective abdominal surgery can be considered as a model for an important acute inflammatory trigger in human participants. The aim of the study was to explore the effect of surgery-induced inflammation on muscle strength, endurance, and self-perceived fatigue and its relation with age. Methods. Sixty-six elective abdominal surgery patients aged 24-91 years were assessed before and at the second and fourth day after surgical intervention. Outcome parameters were grip strength, muscle endurance, fatigue subscale of the Profile of Mood State and visual analog scale for pain, and the circulating inflammatory mediators C-reactive protein, interleukin (IL)-6, and tumor necrosis factor-alpha (TNF-[alpha]). Results. All parameters worsened postoperatively (p < .01) and remained significantly (p < .05) worse until the fourth day postsurgery, except for TNF-[alpha] (no significant change). Older age was related to higher surgery-induced IL-6 levels at the second (p < .05) and fourth postoperative (p < .01) day and to worse self-perceived fatigue and muscle endurance (both p < .05) at the fourth postoperative day. Higher pain levels at the second day following surgery was related to more self-perceived fatigue (p < .05). Worsening muscle endurance following surgery was significantly related to higher IL-6 release following surgery (p < .01) and self-perceived fatigue (p < .05) at the fourth day following the intervention. Age and surgery-induced increase in circulating IL-6 at Day 4 postsurgery was highest in patients showing both worsened muscle endurance and self-perceived fatigue (p < .05). Conclusions. Surgery-induced inflammation is related to reduced muscle endurance and the sensation of fatigue. Elderly patients suffer from a higher impact of surgery on muscle endurance. Key Words: Elderly--Surgery--Acute-phase reaction--Muscle fatigue--Grip strength. doi: 10.1093/gerona/glp145

The purpose was to examine the fatigue pattern of elite female soccer players after competitive games. Soccer players (n = 23) from the Danish women Premier League performed a countermovement vertical jump test, a repeated 30-m sprint test, and the Yo-Yo intermittent endurance level 2 (Yo-Yo IE2) test at rested state and after a competitive game. Average heart rate during the game was 86 [+ or -] 1% of maximal heart rate with no differences between halves. Blood lactate was 5.1 [+ or -] 0.5 mmol*[L.sup.-1] after the first half, which was higher (p < 0.05) than after the second half (2.7 [+ or -] 0.4 mmol*[L.sup.-1]). Yo-Yo IE2 performance was 484 [+ or -] 50 m after the game, which was 62% lower (p < 0.05) than at rested state (1,265 [+ or -] 133 m). Average sprinting time of three 30-m sprints was 5.06 [+ or -] 0.06 seconds after the game, which was 4% slower (p < 0.05) than at rest (4.86 [+ or -] 0.06 seconds). No game-induced effect was observed on vertical jump performance. Significant inverse correlations were observed between Yo-Yo IE2 test performance and fatigue index during the repeated sprint test both at rest (r= -0.76, p < 0.05) and after the game (r = -0.66, p < 0.05). The study demonstrates that the type of fatigue that occurs after a female soccer game does cause marked impairment in intense intermittent exercise and repeated sprint performance but does not affect vertical jump performance. These findings support the notion that decrements in distance covered by sprinting and high-speed running toward the end of elite female games are caused by fatigue. KEY WORDS intermittent exercise performance, sprint, jump, blood lactate, football

Common indices of fatigue may not respond similarly between downhill skiing and other activities because of the influence of factors such as snow conditions, changing terrain, and skiing style. The purpose of this study was to investigate the relationship and predictors of common fatigue indices during downhill skiing. Ten healthy female recreational skiers skied for 3 hours under standardized conditions. Feedback on heart rate (HR) and finishing time were given to each skier at the end of each run to maintain a relatively stable load. A chronic stress score (Cstress) was calculated from creatine kinase (CK), cortisol, and isometric endurance. Finishing times and HR from runs 2, 12, and 24 were similar. Heart rate averaged 82% of HRmax. Heart rate was an insignificant predictor (p = .65) and was poorly correlated (r = 0.16) to Cstress. Blood lactate (LA) was a significant predictor of the Cstress (p = 0.05; r = 0.62). Pre- to postskiing peak forces were not different (p = 0.62), but skiers experienced a significant decrease in isometric endurance from 106.1 [+ or -] 29.6 to 93.2 [+ or -] 24.0 seconds. Endurance decreased by 130/o, whereas cortisol and CK increased by 16 and 42%, respectively. Isometric contraction endurance and blood LA were significant predictors of overall stress. Individual compensation mechanisms and skiing style contributed to highly variable responses during skiing. Whereas HR may indicate stress within a given run, it is not a significant indicator of Cstress and fatigue during recreational alpine skiing. However, the cumulative stress variables and LA can be used in field testing of skiers. It is suggested that LA is a practical on-hill marker of chronic stress. KEY WORDS muscle stress, muscle damage, performance

Fatigue is one of the most common and debilitating complaints of HIV-positive individuals, potentially leading to important functional limitations. We recruited 128 HIV-positive individuals (fatigued and nonfatigued) between March 2005 and May 2006; 66% were male, 66% were African American, 45% had greater than a high school education, 67% were unemployed, and ages ranged from 26-66 (median, 44). Every 3 months for 15 months, participants completed a 56-item self-report fatigue scale developed and validated by the authors. Participants were classified as fatigued or not fatigued at each assessment and received scores for fatigue intensity and impact of fatigue on functioning. We used linear mixed-effects models to assess longitudinal variation in fatigue scores and generalized estimating equations for binary outcomes to model predictors of fatigue remission among those fatigued at baseline. At baseline, 88% of the sample was fatigued. Fatigue measures were highly correlated across time points (p 0.63-0.85 [intensity], 0.63-0.80 [functioning]) and showed no evidence of overall improvement, deterioration, or convergence over time. Predictors of lower fatigue scores included higher income, employment, longer time since HIV diagnosis, and antiretroviral therapy use. Those employed at baseline were likely to show improvements in fatigue while those unemployed were not. Of those fatigued at baseline, 11% experienced remission during follow-up; remission was associated with Caucasian race and employment. In summary, fatigue intensity and related functional limitations were persistent, stable, and unlikely to remit over 15 months of follow-up in this sample of patients with established HIV infection.

Although it has been established that some acute phase responses present differently depending on whether a virus or bacteria activates the innate immune system, it has not yet been established whether fever and sickness behaviors, such as anorexia and lethargy, present differently. We therefore investigated the effects of administering lipopolysaccharide (LPS) and polyinosinic : polycytidylic acid (poly I:C) on body temperature, food intake, body mass, and activity (cage activity and wheel running). Male Sprague-Dawley rats were randomly assigned to receive an intraperitoneal injection of one of LPS (75 µg/kg or 250 µg/kg), poly I:C (3000 µg/kg or 4000 µg/kg), or saline. Administration of LPS or poly I:C induced fever, anorexia, and lethargy. Although voluntary wheel running and cage activity were both significantly reduced after administration of LPS or poly I:C, they were not affected equally. Indeed voluntary wheel running was decreased on average by approximately 30% more than cage activity regardless of the dose or type of mimetic administered. Our results indicate that poly I:C is less effective at inducing anorexia, lethargy, and fever in rats than is LPS, and that avoidance of exercise in animals and humans during infection is likely to be a more prominent feature of illness than is avoidance of routine daily activity. Key words: lipopolysaccharide, polyinosinic : polycytidylic acid, sickness behavior. Il a ete etabli que certaines reponses de phase aigue se presentent differemment selon qu'une virus ou une bacterie active le systeme immunitaire inne; toutefois, on ignore ce qu'il en est des comportements de fievre ou de maladie, comme l'anorexie et la lethargie. Nous avons examine les effets de l'administration de lipopolysaccharide (LPS) et d'acide polyinosinique : polycytidylique (poly I:C) sur la temperature corporelle, l'ingestion de nourriture, la masse corporelle et l'activite (activite de cage et course sur roue). On a soumis aleatoirement des rats Sprague-Dawley males a une injection intraperitoneale de LPS (75 µg/kg ou 250 µ/kg), de poly I:C (3000 µg/kg ou 4000 µg/kg) ou de solution saline. L'administration de LPS ou de poly I:C a induit fievre, anorexie ou lethargie. La course volontaire et l'activite de cage ont diminue de maniere significative apres l'administration de LPS ou de poly I:C, mais a des degres differents. De fait, la course volontaire a diminue en moyenne d'environ 30% de plus que l'activite de cage, independamment de la dose ou du type de substance mimetique administree. Nos resultats indiquent que le poly I:C est moins efficace que le LPS pour induire l'anorexie, la lethargie et la fievre chez les rats et que l'evitement de l'exercice chez les animaux et les humains durant une infection est probablement une caracteristique plus importante de maladie que ne l'est l'evitement d'une activite quotidienne. Mots-cles : lipopolysaccharide, acide polyinosinique : polycytidylique, comportement de maladie. [Traduit par la Redaction], Introduction Fever and sickness behaviors, such as anorexia and decreased activity, are common clinical features of bacterial infections in sick humans and animals (Hart 1988; Plata-Salaman 1996; Cartmell et al. [...]

Nutritional adenosine receptor antagonists can enhance endurance exercise performance in temperate environments, but their efficacy during heat stress is not well understood. This double-blinded, placebo-controlled study compared the effects of an acute dose of caffeine or quercetin on endurance exercise performance during compensable heat stress (40[degrees]C, 20-30% rh). On each of three occasions, 10 healthy men each performed 30-min of cycle ergometry at 50% [Vo.sub.2peak] followed by a 15-min performance time trial after receiving either placebo (Group P), caffeine (Group C; 9 mg/kg), or quercetin (Group Q; 2,000 mg). Serial blood samples, physiological (heart rate, rectal, and mean skin body temperatures), perceptual (ratings of perceived exertion, pain, thermal comfort, motivation), and exercise performance measures (total work and pacing strategy) were made. Supplementation with caffeine and quercetin increased preexercise blood concentrations of caffeine (55.62 [+ or -] 4.77 [micro]M) and quercetin (4.76 [+ or -] 2.56 [micro]M) above their in vitro inhibition constants for adenosine receptors. No treatment effects were observed for any physiological or perceptual measures, with the exception of elevated rectal body temperatures (0.20-0.30[degrees]C; P < 0.05) for Group C vs. Groups Q and P. Supplementation did not affect total work performed (Groups P: 153.5 [+ or -] 28.3, C: 157.3 [+ or -] 28.9, and Q: 151.1 [+ or -] 31.6 kJ; P > 0.05) or the self-selected pacing strategy employed. These findings indicate that the nutritional adenosine receptor antagonists caffeine and quercetin do not enhance endurance exercise performance during compensable heat stress. caffeine; quercetin; thermoregulation; central fatigue; dietary supplements

Background. Older persons often complain of fatigue, but the functional consequences of this symptom are unclear. The aim of the present study was to evaluate fatigue and its association with measures of physical function and disability in a representative sample of the older population. Methods. Cross-sectional data from a population-based sample of 1,055 Italian men and women aged 65 and older were analyzed. Fatigue was defined according to two questions evaluating whether participants felt that 'everything was an effort' and/or they 'could not get going' on three or more days in the past week. Objective measures of physical function were handgrip strength, the Short Physical Performance Battery (SPPB), and 400-m walking speed. Disability was defined as the inability to complete the 400-m walk test and self-reported difficulty in activities of daily living (ADL) and instrumental activities of daily living (IADL). Results. The prevalence of fatigue was higher in women (29%) than in men (15%). In age-adjusted analyses, fatigued men and women had weaker handgrip strength, lower SPPB score, slower walking speed, and higher mobility, ADL, and IADL disability than nonfatigued persons. Further adjustment for health behaviors, diseases, inflammatory markers, and thyroid function generally reduced the relationship between fatigue and functional outcomes, but fatigue remained significantly associated with SPPB score, walking speed, and mobility and IADL disability. Conclusions. Older persons who report fatigue had significantly poorer functional status than those who did not report this symptom. The causal link between fatigue and these outcomes should be further investigated. Key Words: Fatigue--Aging--Disability--Physical function.

The article describes the case of a 43-year-old man who presented to the neuro-oncology clinic with fatigue and lesions in the pituitary and cerebellum. The diagnosis of Erdheim-Chester disease and its management are discussed.

A novel approach to muscle fatigue assessment is proposed. A function is used to map multiple myoelectric parameters representing segments of myoelectric data to a fatigue estimate for that segment. An artificial neural network is used to tune the mapping function and time-domain features are used as inputs. Two fatigue tests were conducted on five participants in each of static, cyclic and random conditions. The function was tuned with one data set and tested on the other. Performance was evaluated based on a signal to noise metric which compared variability due to fatigue factors with variability due to nonfatiguing factors. Signal to noise ratios for the mapping function ranged from 7.89 under random conditions to 9.69 under static conditions compared to 3.34-6.74 for mean frequency and 2.12-2.63 for instantaneous mean frequency indicating that the mapping function tracks the myoelectric manifestations of fatigue better than either mean frequency or instantaneous mean frequency under all three contraction conditions. Index Terms--Dynamic contraction, multivariable mapping, muscle fatigue, myoelectric parameter, neural network.

In the diagnosis of functional weakness and sensory disturbance, positive physical signs are as important as absence of signs of disease. Motor signs, particularly Hoover's sign, are more reliable than [...]

Byline: M. I. Polkey (1), A. Duguet (2), Y. Luo (3), P. D. Hughes (1), N. Hart (1), C.-H. Hamnegard (4), M. Green (1), T. Similowski (2), J. Moxham (3) Keywords: Key words Magnetic stimulation; Phrenic nerves; Diaphragm; Fatigue Abstract: Objective: Anterior magnetic stimulation (aMS) of the phrenic nerves is a new method for the assessment of diaphragm contractility that might have particular applications for the clinical assessment of critically ill patients who are commonly supine. Design: We compared aMS with existing techniques for measurement of diaphragm weakness and fatigue in 10 normal subjects, 27 ambulant patients with suspected diaphragm weakness and 10 critically ill patients. Setting: Laboratory and intensive care unit of two university hospitals. Results: Although aMS was not demonstrably supramaximal in normal subjects, the mean value of twitch transdiaphragmatic pressure (Tw Pdi) obtained at 100 % of stimulator output, 23.7 cm[H.sub.2]O, did not differ significantly from that obtained with bilateral supramaximal electrical stimulation (ES), 24.9 cm[H.sub.2]O, or bilateral anterior magnetic phrenic nerve stimulation (BAMPS), 27.3 cm[H.sub.2]O. A fatiguing protocol produced a 20 % fall in aMS-Tw Pdi and a 19 % fall in BAMPS-Tw Pdi the fall in aMS-Tw Pdi correlated with the fall in BAMPS-Tw Pdi (r .sup.2 = 0.84, p = 0.03) indicating that aMS can detect diaphragm fatigue. In ambulant patients aMS agreed closely with existing measures of diaphragm strength. The maximal sniff Pdi correlated with both the aMS-Tw Pdi (r .sup.2 = 0.60, p < 0.0001) and the BAMPS-Tw Pdi (r .sup.2 = 0.65, p < 0.0001) and the aMS-Tw Pdi was a mean (SD) 2.2 (4.3) cm[H.sub.2]O less than BAMPS-Tw Pdi. In addition, aMS correctly identified diaphragm dysfunction in patients studied on the ICU. Conclusions: We conclude that aMS is of clinical value for the investigation of suspected diaphragm weakness. Author Affiliation: (1) Respiratory Muscle Laboratory, Royal Brompton Hospital, Fulham Rd, London SW3 6NP, UK e-mail: m.polkey@rbh.nthames.nhs.uk Tel. + 44-1 71-3 51 89 39 Fax: + 44-1 71-3 51 80 29, GB (2) Laboratoire de Physiopathologie Respiratoire & Unite de Reanimation, Service de Pneumologie, Groupe Hospitalier Pitie-Salpetriere, Assistance Publique-Hopitaux de Paris and UPRES EA 2379, Universite Paris VI, Paris, France, FR (3) Respiratory Muscle Laboratory, Kings College Hospital, Bessemer Rd, London SE5 9PJ, UK, GB (4) Department of Pulmonary Medicine, Sahlgrenska University Hospital, S-413 45 Goteborg, Sweden, SE Article note: Received: 11 November 1999 Final revision received: 17 April 2000 Accepted: 26 April 2000

Myoelectric manifestations of muscle fatigue have been described by monitoring the first-order moment (mean frequency) of the power spectral density function during voluntary or electrically elicited sustained contractions. Higher order central moments provide additional information about the width, skewness, and kurtosis of the spectrum and its shape changes, thereby providing a description of slow nonstationarities more accurate than that allowed by the mean frequency alone. In 1986, B. Saltzberg introduced a method of representing the moments of the power spectral density function of band limited signals, without computing the Fourier transform, as weighted sums of samples of the autocorrelation function. If we allow for oversampling of the signal (and therefore of its autocorrelation function), more efficient weighted sums can be found which give Saltzberg's formula as a limiting case. The faster rate of decay of the weights implies a faster convergence of the estimates and the need to compute fewer samples of the autocorrelation function. The algorithm is particularly suitable for: 1) analysis of evoked potentials (M-waves), because it does not need zero padding to increase resolution and operates on any number of samples, and 2) on-line implementation by dedicated microprocessors performing simultaneous spectral moment analysis on a number of parallel channels.