bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Probabilistic Fracture Mechanics to Offshore Structures
Authors: Kirkemo Finn
Published: June 2009

For offshore structures the fatigue limit state is governing the structural dimensions of several members and joint connections. Safety against fatigue failure is achieved through a combination of design requirements and performance of in-service inspections with repair of detected fatigue cracks. A review of uncertainties involved in fatigue life predictions by fracture mechanics is presented with particular reference to steel structures. Sources of uncertainties considered are: environmental conditions, hydrodynamic loading, global structural analysis, local stress calculation at fatigue sensitive points, and fatigue crack growth modeling by fracture mechanics. A probabilistic model using the fracture mechanics in probabilistic form is presented. This model accounts for uncertainties in loading, initial and critical defect sizes, material parameters, and in the uncertainty related to computation of the stress intensity factor. Failure probabilities are computed by first-order reliability methods and sensitivity factors are determined. Model updating based on in-service inspection results is formulated. Uncertainties with respect to detecting a crack and to correctly sizing a crack are included. Experience on application of the analysis method is presented.
Ductile Fracture Propagation and Arrest in Offshore Pipelines
Authors: Demofonti G. , Maresca A. , Buzzichelli G.
Published: June 2009

The problem of ductile fracture propagation in pipelines, already extensively studied in the past in the case of buried pipelines, has been receiving the close attentions of research institutes and companies in the last decade or so for offshore pipelines too; the aim is to allow a correct choice of toughness levels of the steels employed for such applications. The first studies in the field consisted essentially in model tests; more recently full-scale tests were performed, while at the same time the first attempts were made to interpret and model marine backfill. As a result the main effects of marine backfill on ductile propagation were put into evidence and quantified. In particular, because of the overpressure field generated around the pipe subsequently to fracture initiation, the marine backfill comes out to be more effective than soil in arresting a running fracture, and consequently very low toughness levels are required for offshore pipelines.
Japanese Research Activities on Offshore Fracture Mechanics Applications
Authors: Machida S. , Yajima H. , Toyosada M. , Hagiwara Y. , Kajimoto K.
Published: June 2009

The brittle fracture, for its catastrophic nature, is one of the most important factors for designing offshore structures especially operating in the cold sea. Fracture mechanics method can provide a useful tool to maintain the reliability of structural integrity. This paper gives descriptions on a proposed method for fracture assessment with experimental verifications, and also informations from some recent Japanese research activities associated with the application of fracture mechanics to the offshore structures, i.e. initial defect size evaluation, a practical method for evaluation of the local strain in strain concentrated structural components, effect of strain rate on fracture toughness and fracture toughness of weldments.
Thermophysical Properties Research on Fluids at the Technology Frontier: Status of Current Research
Authors: Nagashima Akira
Published: June 2009

Key information strongly needed for development of new technologies includes thermophysical property data of various substances, such as high temperature molten semiconductor materials, nonazeotropic working fluids, liquid crystals, geothermal brines, high temperature combustion products, bioliquids, and so on. To meet these demands, new experimental and theoretical techniques have to be effectively developed. In this article, the present status of available information, experimental research, and major experimental difficulties is reviewed. The focus is on transport properties and calorific properties of substances in fluid state, considering the lack of reliable data on these properties. Considering fast technological progress and also limited space, references published in the last ten years have mainly been reviewed.
Stochastic Averaging Methods in Random Vibration
Authors: Zhu W. Q.
Published: June 2009

A survey of stochastic averaging methods in random vibration is given. After a brief introduction to the basic ideas, the advantages and the history of the methods, three kinds of stochastic averaging methods are formulated, and their applicability and recent developments are stated. In the second part, the applications of the methods in response prediction, stability decision, and reliability estimation of randomly excited nonlinear and parametric systems are reviewed. The possibility of further developments and applications of the methods is also pointed out.
Finite Element Methods in Probabilistic Structural Analysis: A Selective Review
Authors: Benaroya H. , Rehak M.
Published: June 2009

This review examines the field of structural analysis where finite element methods (FEMs) are used in a probabilistic setting. The finite element method is widely used, and its application in the field of structural analysis is universally accepted as an efficient numerical solution method. The analysis of structures, whether subjected to random or deterministic external loads, has been developed mainly under the assumption that the structure’s parameters are deterministic quantities. For a significant number of circumstances, this assumption is not valid, and the probabilistic aspects of the structure need to be taken into account. We present a review of this emerging field: stochastic finite element methods. The terminology denotes the application of finite element methods with a probabilistic context. This broad definition includes two classes of methods: (i) first- and second-order second moment methods, and (ii) reliability methods. This paper addresses only the first category, leaving the second to specialists in that area. The contribution of this review is to illustrate the similarities and differences of the various methods falling in the first category. Also excluded from this review are simulation methods such as Monte Carlo and response surface, and methods that use FEM to solve deterministic equations (Fokker–Planck) governing probability densities. The essential conclusion is that the second moment methods are mathematically identical to the second order (except for the Neumann expansion). The essential distinction that can be made regarding stochastic FEM is the nature of the structure: It can be deterministic or random. By random structure is meant one with parameters that have associated uncertainties, and thus which must be modeled in a random form. Although the randomness in the structure can be of three types, random variable, random process in space, and random process in time, discussion will be limited to the first two categories. While keeping the emphasis on finite element methods, other techniques involving finite differences, which are useful in the study of multi-degree-of-freedom systems, are briefly mentioned. The present review covers only developments that are derived from the engineering literature, thus implying near-term applicability.
Unsteady Transonic Aerodynamics and Aeroelasticity
Authors: Dowell Earl H.
Published: June 2009

In recent years substantial progress has been made in the development of an improved understanding of unsteady aerodynamics and aeroelasticity in the transonic flow regime. This flow regime is often the most critical for aeroelastic phenomena; yet it has proven the most difficult to master in terms of basic understanding of physical phenomena and the development of predictive mathematical models. The difficulty is primarily a result of the nonlinearities which may be important in transonic flow. Emerging mathematical models have relied principally on finite difference solutions to the governing nonlinear partial differential equations of fluid mechanics. Here are addressed fundamental questions of current interest which will provide the reader with a basis for understanding the recent and current literature in the field. Four principal questions are discussed: (1) Under what conditions are the aerodynamic forces essentially linear functions of the airfoil motion? (2) Are there viable alternative methods to finite difference procedures for solving the relevant fluid dynamical equations? (3) Under conditions when the aerodynamic forces are nonlinear functions of the airfoil motion, what is the significance of the multiple (nonunique) solutions which are sometimes observed? (4) What are effective, efficient computational procedures for using unsteady transonic aerodynamic computer codes in aeroelastic (e.g., flutter) analyses?
Recent psychopathology, suicidal thoughts and suicide attempts in households with and without firearms: findings from the National Comorbidity Study Replication
Authors: Miller M , Barber C , Azrael D , Hemenway D , Molnar B E
Published: June 2009

Objective:

To assess the relationship between firearm ownership and possible psychiatric confounders of the firearm–suicide relationship.

Methods:

Multivariate logistic regression was used to estimate the association between living in a home with firearms and 12-month occurrence of majorDiagnostic and statistical manual of mental disorders(DSM)-IV disorders and suicidal behaviour among respondents to the National Comorbidity Survey Replication, a household survey of 9282 adults aged 18+. Analyses controlled for sociodemographic characteristics including age, sex, race/ethnicity, educational attainment and poverty.

Results:

Approximately one in three Americans reported living in a home with firearms. People living in a home with firearms were no more or less likely than people in homes without firearms to have recent (past year) anxiety disorders (OR = 1.0, 95% CI 0.8 to 1.2), mood disorders (OR = 0.9, 95% CI 0.7 to 1.1) or substance dependence and/or abuse (OR = 0.9, 95% CI 0.6 to 1.3). Past year suicidal ideation (OR = 0.8, 95% CI 0.5 to 1.3) and suicide planning (OR = 0.5, 95% CI 0.2 to 1.4) were also not associated with living in households with firearms. Having made a suicide attempt over the previous year was the only outcome more common among participants reporting that they currently lived in a home with firearms.

Conclusions:

The previously reported association between household firearm ownership and heightened risk of suicide is not explained by a higher risk of psychopathology among gun-owning families. As there are Americans with suicidal ideation and/or significant and recent psychiatric disorders currently living in homes with firearms, future work should focus on understanding the impediments to effectively communicating the suicide risk associated with household firearms.
Mechanisms involved in the recent large reductions in US road fatalities
Authors: Sivak M
Published: June 2009

Road fatalities in the USA have recently decreased, and these reductions are greater than the corresponding reductions in the amount of driving. A multiple regression analysis was performed on monthly data from January 2007 through December 2008. The dependent variable was the number of road fatalities. The independent variables were distance driven, proportion of driving on rural roads, and the average price of unleaded gasoline as a proxy for the proportion of leisure driving. The results suggest that the larger-than-expected fall in road fatalities is partly a consequence of the disproportional decreases in rural driving (which is more risky than urban driving) and leisure driving (which is more risky than commuter driving).
Obesity Reduction Through Lifestyle Modification
Authors: Ross Robert , Janssen Ian , Tremblay Angelo
Published: June 2009

Obesity is a worldwide public health problem. One in three Canadians is overweight, a prevalence that is already high and increasing. Moreover, 54% of men and 37% of Canadian women are characterized as abdominally obese, the phenotype that is strongly associated with cardiovascular disease and type II diabetes. These observations underscore the importance of considering the efficacy of methods commonly used to reduce total and abdominal obesity. These strategies include a decrease in energy intake (diet), an increase in energy expenditure (exercise), or pharmacological intervention. The combination of diet and exercise is more commonly prescribed, with pharmacological intervention suggested only when lifestyle changes fail to achieve weight loss.The aim of this report is to review current knowledge regarding the influence of diet and exercise as treatment strategies for obesity reduction and provide recommendations for attaining and maintaining a healthy weight. The importance of diet composition in the treatment of obesity is also considered. Key words: body fat, weight loss, exercise, diet
Exercise and Training in Women, Part I: Influence of Gender on Exercise and Training Responses
Authors: Shephard Roy J.
Published: June 2009

Exercise and training responses in women are briefly reviewed. Part I of the paper considers the influence of gender on such responses. The average woman has a smaller inherent aerobic power and less muscular strength than a man, reflecting sociocultural influences, physical size, body composition, and hormonal milieu. Nevertheless, the best-trained women can out-perform sedentary men. The handicap of the average woman is offset by a lighter body mass and a tendency to metabolize fat rather than carbohydrate during exercise. A lack of anabolic hormones may limit training increases of muscle bulk in the female. A low initial fitness may enhance the scope for training tolerance, but it also limits tolerance of conditioning. Nevertheless, women seem less vulnerable than men to exercise-induced sudden death and overtraining. Part II of the review considers the influence of the menstrual cycle and pregnancy upon exercise and training responses. Physical activity programmes for young women should take account of possible pregnancy. Potential dangers to the foetus include an excessive rise of core body temperature, a decrease of maternal blood sugar, and foetal hypoxia. Nevertheless, regular moderate exercise generally has a favourable impact upon pregnancy outcomes. Key Words: sex differences, sociocultural issues, biological differences, physical activity, conditioning, menstruation, pregnancy, employment standards
The Efficacy of SPORTTM as a Dietary Supplement on Performance and Recovery in Trained Athletes
Authors: Timmons Brian W. , Newhouse Ian J. , Thayer Robert E. , McAuliffe Jim E. , McIllwaine Steve
Published: June 2009

This study investigated the efficacy of SPORTTM (a popular dietary supplement) in improving performance and assisting recovery in 9 trained athletes. In a double-blind, crossover experiment, subjects ran at workloads of 60 and 80% of peak oxygen uptake [Formula: see text] for 5 min each with 5 min recovery after each bout and at 100% [Formula: see text] until exhaustion. Two capsules of either SPORTTM or a gelatin placebo were administered 1 hr prior to exercise and immediately after each workload. Heart rate (HR) and blood lactate (BLa) were measured at 1 hr prior to exercise, immediately after the 100% exercise bout and at 5, 10, 20, and 45 min during recovery. No significant differences between treatments on HR and BLa measures at any of the 6 time periods, or on subjects' time to exhaustion were found. Under the conditions of this experimental design, SPORTTM had no beneficial effects on performance or recovery in trained athletes. Key Words: blood lactate, dioscorea, heart rate, ergogenic aid, time to exhaustion
Ventilatory Threshold and Maximal Oxygen Uptake in Present Triathletes
Authors: Hue Olivier , Gallais Daniel Le , Chollet Didier , Préfaut Christian
Published: June 2009

The aim of this study was to determine the physiological profile of young triathletes who began triathlon competition as their first sport. Twenty-nine male competitive triathletes (23 regionally and nationally ranked triathletes and 6 elite, internationally ranked triathletes) performed two tests, one on a cycle ergometer [Formula: see text] and one on a treadmill [Formula: see text] Results showed (a) no difference between CE [Formula: see text] and TM [Formula: see text] in the triathletes (69.1 ± 7.2 vs. 70.2 ± 6.2 mL•kg−1•min−1, respectively), (b) values of CE [Formula: see text] and TM [Formula: see text] in elite triathletes (75.9 + 5.2 and 78.5 ± 3.6 mL•kg−1•min−1, respectively) that were comparable to those reported in elite single-sport athletes in these specialities, and (c) although the ventilatory threshold (Thvent) was similar in CE and TM. TM Thvent was consistently lower for triathletes than TM Thvent usually reported for runners. Key Words: triathlon, cross-training adaptations, elite triathletes
Effects of Exercise and Alkalosis on Serum Insulin-Like Growth Factor I and IGF-Binding Protein-3
Authors: Kraemer William J. , Harman Fred S. , Vos Netty H. , Gordon Scott E. , Nindl Bradley C. , Marx Jim O. , Gómez Ana L. , Volek Jeff S. , Mazzetti Nicholas A. Ratamess. Scott A. , Bush Jill A. , Dohi Keiichiero , Newton Robert U. , Häkkinen Keijo
Published: June 2009

This investigation examines the effects of orally induced alkalosis on serum IGF-1 and IGFBP3 concentrations in response to an acute 90-s bout of high intensity cycle exercise. Ten healthy, active men, ages 24.60 ± 4.90 years, participated in a randomized, doubleblind, counterbalanced trial order with a cross-over design. Subjects ingested an experimental bicarbonate solution or a placebo solution. Blood was sampled at baseline; pre-exercise: and 0, 5, 10, and 30 min postexercise. The pH between groups for pre-exercise and postexercise time points differed significantly (p < .05) in the experimental condition (from 7.42 ± 0.01 to 7.35 ± 0.02) versus the placebo condition (from 7.36 ± 0.01 to 7.25 ± 0.03). Increases in IGF-1 over resting conditions occurred with placebo conditions at 5 and 10 min postexercise and in the experimental condition at 5 min postexercise. Concentrations of IGFBP3 were elevated above baseline at IP in both experimental and placebo conditions. Key Words: hormones, physical stress, anaerobic exercise, acid-base balance, pH
Adaptations in the Muscle Cell to Training: Role of the Na+-K+-Atpase
Authors: Green Howard J.
Published: June 2009

The plasticity of skeletal muscle is evident following the onset of regular contractile activity where extensive adaptations can be observed at all levels of organization. Among the properties subject to altered regulation is the Na+-K+-ATPase, an integral membrane protein distributed throughout the sarcolemma and t-tubule, which functions to maintain high Na+ and K+ transmembrane gradients. This protein is uniquely positioned to control muscle excitation and contraction processes, metabolic flux rates, and contractility. Pronounced and rapid upregulation in the Na+-K+-ATPase content can be observed within the first days of exercise and well before the other major ATPase proteins involved in Ca2+ and actomyosin cycling. Moreover, the Na+-K+-ATPase is subject to complex messenger regulation, involved both in the accommodation and the adaptive responses to contractile activity. This emphasizes that adaptive responses can be mediated soon after the onset of training and may have profound affects on muscle contractility and other cellular adaptations. Key Words: muscle, strain, exercise, adaptation, accommodation
A Comparison of Critical Velocity Estimates to Actual Velocities in Predicting Simulated Rowing Performance
Authors: Kennedy Michael D.J. , Bell Gordon J.
Published: June 2009

The most accurate critical velocity (CV) estimate for the prediction of velocity during a simulated 2,000-m rowing race and the relationship to aerobic power were studied. Sixteen male rowers completed randomized maximal exertion trials (200, 400, 600, 800, 1,000, and 1,200 m), a maximal oxygen consumption [Formula: see text] on a Concept II rowing machine, and an actual 2,000-m simulated rowing race. Three mathematical models were applied to 4 rowing distance combinations producing 12 CV estimates. Seven of the 12 possible CV estimates were not significantly different from actual 2,000-m velocity. Comparison of the 3 CV models using all 6 trial distances revealed that the nonlinear model produced a CV estimate lower than the 2 linear CV models. CV was significantly correlated to [Formula: see text] (r = 0.91) and the mean velocity achieved during the 2,000-m simulated rowing race (r = 0.97). [Formula: see text] was significantly correlated to 2,000-m simulated rowing race velocity (r = 0.93). Key words: maximal oxygen consumption, critical power, critical speed
Health-Related Fitness, Physical Activity, and History of Back Pain
Authors: Payne Nancy , Gledhill Norman , Katzmarzyk Peter T. , Jamnik Veronica
Published: June 2009

The relationship between history of back pain and measurements of both health-related fitness and physical activity participation was examined in 233 males and 287 females, aged 15-69 years. Participants were divided by gender into those reporting no history (NH) or a history (H) of recurring back pain. Analysis of variance indicated that trunk flexion, back extensor endurance, and physical activity participation were significantly higher for NH and waist girth significantly lower for NH in both genders. In females, mean abdominal muscular endurance was significantly higher in NH. Forward stepwise discriminant function analyses indicated that the best discriminators between NH and H were back extensor endurance and physical activity participation in both genders and waist girth in females. These findings support using measurements of trunk flexion, abdominal muscular endurance, back extensor endurance, physical activity participation, and waist girth as indicators of back fitness in the evaluation of back health. Key words: back fitness, back extensor endurance, trunk flexion, curl-ups, waist girth
Electromyographic and Mechanomyographic Responses at Critical Power
Authors: Bull Anthony J. , Housh Terry J. , Johnson Glen O. , Perry Sharon R.
Published: June 2009

The purpose of the present study was to determine the electromyographic (EMG) and mechanomyographic (MMG) responses to cycle ergometry at critical power (CP). Seven moderately active males (25 ± 3 years) completed a 60-min trial at their CP estimated from a nonlinear, 3 parameter regression model. EMG and MMG amplitudes were recorded from the vastus lateralis during 60-min continuous rides at CP. The mean CP was 175 ± 25 W, which represented 56 ± 5% of the subjects' peak power outputs. The results indicated that the slope coefficient for the EMG amplitude versus time relationship was not significantly different from zero; however, MMG amplitude decreased significantly over the 60 min. This dissociation between the electrical (EMG) and mechanical (MMG) aspects of muscular activity during cycle ergometry may be due to neuromuscular changes associated with "muscle wisdom" or changes in muscular compliance. Key words: cycle ergometry, fatigue, muscle wisdom, [Formula: see text] slow component
Gender Differences in Physiology: Introduction to the Symposium
Authors: Tarnopolsky Mark A.
Published: June 2009

not available
Effect of Maternal Exercise on Fetal and Placental Glycogen Storage in the Mature Rat
Authors: Houghton P.E. , Mottola M.F. , Plust J.H. , Schachter C.L.
Published: June 2009

The purpose was to determine the effects of exercise on fetal and placental glycogen storage patterns at 20 days gestation (term 21 days) in mature (approximately 12 months of age) Sprague-Dawley rats. The exercise protocol consisted of treadmill running at 30 m min−1, on a 10 incline, for 60 min, 5 days per week, for 4 weeks prior to conception, which continued until day 19 of pregnancy. Exercise produced a significant reduction in fetal body weight, placental weight, and fetal organ weights (heart, kidney, brain, and liver) compared to sedentary control animals (p < .05). However, when fetal body size was taken into account, these differences disappeared, except for the fetal brain:body weight ratio, which was larger in the exercised animals compared to controls (p < .05). Fetal liver glycogen concentrations were significantly lower in exercised animals compared to nonrunning control animals (p < .05). These results demonstrate that exercise of mature rats may compromise fetal development and hepatic glycogen storage in the fetus. Key words: age, exercise, pregnancy, fetal glycogen storage patterns
Nutritional Supplementation and Resistance Exercise: What Is the Evidence for Enhanced Skeletal Muscle Hypertrophy?
Authors: Gibala Martin J.
Published: June 2009

Many athletes and recreational weightlifters believe that dietary manipulations-either following a single bout of resistance exercise or during habitual training-may augment the normal gains in muscle fibre hypertrophy. Very few studies, however, have directly examined the effect of nutritional supplementation on muscle protein metabolism after resistance exercise. Ingestion of an amino acid and/or carbohydrate solution during the initial hours following a single bout of resistance exercise promotes an acute increase in protein net balance compared to the fasted state. The precise mechanism involved has not been elucidated but seems related to an increased availability of intracellular amino acids and/or an increase in plasma insulin concentration. As a practical recommendation, therefore, postexercise feeding appears to be very important. Recent evidence suggests that creatine supplementation in conjunction with resistance training may elicit larger increases in muscle fibre cross-sectional area compared to training alone. This intervention may be most beneficial in persons with "compromised" skeletal muscle. Key words: protein metabolism, amino acids, creatine, insulin, human
Hyperhydration and Glycerol: Thermoregulatory Effects During Exercise in Hot Climates
Authors: Latzka William A. , Sawka Michael N.
Published: June 2009

Hyperhydration or increasing body water content above normal (euhydration) level was thought to have some benefit during exercise heat-stress; however, attempts to overdrink have been minimized by a rapid diuretic response. The perception that hyperhydration might be beneficial for exercise performance and for thermoregulation arose from the adverse consequences of hypohydration. Many studies had examined the effects of hyperhydration on thermoregulation in the heat; however, most of them suffer from design problems that confound their results. The design problems included control conditions not representing euhydration but hypohydration, control conditions not adequately described, cold fluid ingestion that reduced core temperature, and/or changing heat acclimation status. Several investigators reported lower core temperatures during exercise after hyperhydration, while other studies do not. Some investigators reported higher sweating rates with hyperhydration, while other studies do not. Recent research that controlled for these confounding variables reported that hyperhydration (water or glycerol) did not alter core temperature, skin temperature, whole body sweating rate, local sweating rate, sweating threshold temperature, sweating sensitivity, or heart rate responces compared to euhydration trail. If euhydration is maintained during exercise-heat stress then hyperhydration appears to have no meaningful advantage. Key words: Hydration, fluid replacement, exercise heat-stress, total body water exercise
Forearm Vasoreactivity in Type I Diabetic Subjects
Authors: Allen Jason D. , Welsch Michael , Aucoin Nikki , Wood Robert , Lee Matt , Leblanc Kim Edward
Published: June 2009

This study compared forearm vasoreactivity in 15 Type 1 diabetic subjects with 15 healthy controls. The groups were matched for age, exercise capacity, and the absence of other cardiovascular risk factors. Vasoreactivity was measured using strain gauge plethysmography, at rest, after arterial occlusion (OCC), and following OCC coupled with handgrip exercise (ROCC). Forearm blood flows were significantly elevated between conditions 2.58 ± 0.37 ml/100mltissue at rest to 26.80 ± 6.56 after OCC and 32.80 ± 8.26ml/100mltissue following ROCC in Type 1 diabetic subjects. There were no differences in forearm blood flow between groups for any of the conditions. These data indicate the degree of forearm blood flow is directly related to the intensity of the vasodilatory stimulus. However, our study did not reveal evidence of impaired vasodilatory capacity in Type 1 diabetic subjects compared to controls in the absence of other risk factors. Key words: IDDM, vascular function, exercise, fitness, and reactive hyperemia
Sarcopenia (Muscle Wasting) and Aging: Significance of Exercise Introduction to the Symposium
Authors: Ross Robert , Heymsfield Steven B.
Published: June 2009

not available
Skeletal Muscle Mass and Aging: Regional and Whole-Body Measurement Methods
Authors: Lee Robert C. , Wang Zimian , Heymsfield Steven B.
Published: June 2009

Skeletal muscle is a large compartment that can now be quantified using research and clinically applicable regional and whole-body methods. The most important advances are the two imaging methods, computed tomography (CT) and magnetic resonance imaging (MRI). Both CT and MRI can serve as regional and whole-body reference methods when evaluating other approaches for estimating skeletal muscle mass. Imaging methods also afford the opportunity to quantify both anatomic skeletal muscle and the smaller adipose-tissue free skeletal muscle component. Other available methods for estimating skeletal muscle, either regional or at the whole body level, include dual-energy x-ray absorptiometry, in vivo neutron activation analysis-whole body counting, anthropometry, ultrasound, bioimpedance analysis, and urinary metabolite markers. Each method is reviewed in the context of the aging process, cost, availability, practicality, and desired accuracy. New insights should be possible when skeletal muscle mass, measured using these methods, is combined with other descriptors of muscle biochemical and mechanical function. Key words: skeletal muscle mass, aging, nutritional assessment, function
Introduction to the Review Papers Pertaining to Components of the Canadian Physical Activity, Fitness and Lifestyle Appraisal
Authors: Gledhill Norman
Published: June 2009

not available
The Effects of Changes in Musculoskeletal Fitness on Health
Authors: Warburton Darren E.R. , Gledhill Norman , Quinney Arthur
Published: June 2009

The objective of this review is to examine the effects of changes in the individual components of musculoskeletal fitness on indicators of health status. Available evidence regarding the impact of changes in musculoskeletal fitness on indicators of health status is summarized and evaluated. Intervention programs designed specifically to enhance musculoskeletal fitness have been effective in improving several indicators of health status including glucose metabolism, obesity, bone health, independent living, the incidence of falling and associated injuries, and/or psychological well-being. An enhanced musculoskeletal fitness is associated with an improvement in health status. Key words: strength, muscular endurance, power, flexibility, health status
Musculoskeletal Fitness and Health
Authors: Warburton Darren E.R. , Gledhill Norman , Quinney Arthur
Published: June 2009

The purpose is to examine the relationship between musculoskeletal fitness and health status. Muscular strength is positively associated with independence and overall quality of life, and negatively associated with morbidity and potentially premature mortality. Muscular endurance is positively related to overall quality of life. Elevated muscular endurance may reduce the incidence of falling and its associated injuries. Muscular power is predictive of functional capacity, resultant disability, and potentially premature mortality. Flexibility is positively associated with mobility and independence. Women and the aged may be susceptible to musculoskeletal impairments leading to reduced health status and thus may represent primary target groups for intervention programs. High levels of musculoskeletal fitness are associated with positive health status, and low levels of musculoskeletal fitness are associated with lower health status. Key words: fitness assessment, strength, muscular endurance, power, flexibility, health status, risk factors
Factors Affecting Force Loss With Prolonged Stretching
Authors: Behm David G. , Button Duane C. , Butt Jeremy C.
Published: June 2009

The purpose of this study was to investigate factors underlying the force loss occurring after prolonged, static, passive stretching. Subjects were tested before and 5-10 min following 20 min of static, passive stretching of the quadriceps (N = 12) or a similar period of no stretch (control, N = 6). Measurements included isometric maximal voluntary contraction (MVC) force, surface integrated electromyographic (iEMG) activity of the quadriceps and hamstrings, evoked contractile properties (twitch and tetanic force), and quadriceps inactivation as measured by the interpolated twitch technique (ITT). Following stretching, there was a significant 12% decrement in MVC with no significant changes in the control group. Muscle inactivation as measured by the ITT and iEMG increased by 2.8% and 20.2%, respectively. While twitch forces significantly decreased 11.7%, there was no change in tetanic force post-stretch. Although possible increases in muscle compliance affected twitch force, a lack of tetanic force change would suggest that post-stretch force decrements are more affected by muscle inactivation than changes in muscle elasticity. Key Words: antagonist, electromyography, maximum voluntary contraction, muscle activation, twitch, tetanus
Contribution of Visceral Obesity to the Insulin Resistance Syndrome
Authors: Lemieux Simone
Published: June 2009

A high visceral adipose tissue accumulation has been associated with many metabolic perturbations typical of the insulin resistance syndrome, such as dyslipidemia, impaired glucose-insulin homeostasis, hypertension, and impaired fibrinolysis. It has been documented that male gender, aging, and a hyperglycemic state are conditions that increase the likelihood of displaying features of the insulin resistance syndrome. Accordingly, studies have demonstrated that the variation in visceral adipose tissue accumulation explains a significant proportion of the gender differences in the metabolic risk profile. Age-related differences in metabolic components of the insulin resistance syndrome have also been shown to be partly explained by the concomitant increase in visceral adipose tissue accumulation found with age. Studies have suggested that a high visceral adipose tissue accumulation contributes significantly to the deterioration in the plasma lipid-lipoprotein profile found in hyperglycemic subjects. Finally, it appears that the clustering of metabolic alterations of the insulin resistance syndrome is more pronounced in obese subjects with high levels of visceral fat than in those with a lower visceral adipose tissue accumulation. Key Words: abdominal fat, dyslipidemia, glucose-insulin homeostasis, type 2 diabetes, cardiovascular disease
The Incidence of Hematuria in Middle Distance Track Running
Authors: Jones Gareth R. , Newhouse Ian J. , Jakobi Jennifer M. , Lavoie Norm , Thayer Robert
Published: June 2009

The purpose of this study was to establish if middle distance track athletes experience hematuria during their competitive season interval workouts and, if so, what type of workout based on intensity and distance was most associated with hematuria. During a 4-week observational period, athletes (n = 10) underwent reagent strip urinalysis before and after their twice weekly interval sessions. Positive samples for hematuria were analyzed microscopically to accurately determine red blood cell (RBC) loss. Seventy-one individual interval workouts were observed, of which 32 cases of hematuria were reported. Nine cases of hematuria exhibited > 100 RBC per High Power Field (Hpf). Furthermore, 90% of the athletes experienced post-workout hematuria at least once. The highest incidence of hematuria was observed after workouts run at 110% of [Formula: see text] over short (600-1,500 m) to moderate (1,501-3,000 m) distances. All post-exercise cases of hematuria resolved within 2 hr of recovery. Key words: hematuria, running, training, urinalysis
The Response at the Onset of Severe Intensity Exercise
Authors: Hill David W. , Stevens Emily C.
Published: June 2009

Fourteen participants achieved a peak [Formula: see text] of 2573 ± 738 ml • min−1 in ∼3 1/2-min cycle ergometer tests. However, in the first 45 s of exercise, formal description of the phase II of the [Formula: see text] response indicated that the [Formula: see text] was projecting toward a value of 3451 ± 1599 ml • min−1, well above the peak [Formula: see text]peak and not different from the predicted O2 demand of 3389 ± 800 ml • min−1. We conclude that, at the onset of exercise in the severe intensity domain, [Formula: see text] is initially driven toward the O2 demand, and then is limited by the achievable [Formula: see text][Formula: see text]Key words: aerobic, kinetics, oxygen uptake, severe, [Formula: see text][Formula: see text]
Respiratory Muscle Injury: Evidence to Date and Potential Mechanisms
Authors: Reid W. Darlene , Clarke Tyler James , Wallace Alison M.
Published: June 2009

Respiratory muscle dysfunction associated with ventilatory loading may be partially attributed to respiratory muscle injury. Exertion-induced muscle injury can be defined as structural alterations of the muscle, however, a better understanding of the biochemical, morphologic, and functional correlates of injured respiratory muscles will facilitate discrimination of how injury, fatigue, and weakness contribute to respiratory muscle dysfunction. In addition to the increased loads associated with lung disease, many factors such as poor arterial blood gases, immobilization, sepsis, decreased nutrition, and corticosteroids may increase susceptibility to exertion-induced respiratory muscle injury. Respiratory muscle injury in humans is not well-described, however, more extensive evidence has been shown in animal models of increased ventilatory loading. Potential mechanisms of respiratory muscle injury are mechanical stress, metabolic stress, and inflammation. In order to optimize therapeutic interventions, a better understanding of these mechanisms and the patients that are most susceptible to respiratory muscle injury needs to be determined. Key words: resistive loading, respiratory muscles, exertion, muscle adaptation, muscle injury
Physical Activity Assessment Options Within the Context of the Canadian Physical Activity, Fitness, and Lifestyle Appraisal
Authors: Tremblay Mark S. , Shephard Roy J. , Mckenzie Thomas L. , Gledhill Norman
Published: June 2009

The Canadian Physical Activity, Fitness, and Lifestyle Appraisal (CPAFLA) is a standardized battery of tests that is commonly used to assess asymptomatic individuals. This paper reviews evidence concerning the reliability, validity, and utility of the procedure currently used to assess habitual physical activity in the CPAFLA and surveys available physical activity assessment options. Special considerations related to age, gender, ethnicity, seasonal variations, and within-week variance are discussed. The potential assessment options are discussed with consideration given to the logistical and pragmatic constraints inherent in the CPAFLA. New technologies for future assessment of physical activity are briefly presented and recommendations for future research forwarded. Key words: energy expenditure, activity monitoring, motion sensors, habitual physical activity, fitness assessment
Pulmonary Responses During the Cycle-Run Succession in Elite and Competitive Triathletes
Authors: Hue Olivier , Galy Olivier , Gallais Daniel Le , Préfaut Christian
Published: June 2009

Objectives: The purpose of this study was to determine the effect of performance level on the pulmonary responses in triathletes during the cycle-run succession. Methods: Eight regionally and nationally ranked (Competitive) and six internationally ranked (Elite) male triathletes underwent 30 min of cycling followed by 20 min of running (C-R) and 30 min of control cycling (C). Before and 10 min after each trial, the triathletes underwent lung function testing. Ventilalory data were collected every minute using an automated breath-by-breath system. Results: The results showed that (a) cycling induced a significant increase in residual volume and functional residual capacity in the Elite group (P < .05); (b) although cycling induced a significant decrease in DLCO in both groups, this decrease persisted at the end of the cycle-run exercise in the Competitive group only (P < .05); and (c) the rise in breathing frequency was significantly greater in the Competitive triathletes during the first 8 min of the subsequent run (P < .04). Conclusions: We conclude that the internationally ranked-or elite-performance-triathletes may have developed specific responses to the cycle-run succession. Key words: triathlon, elite triathlete, performance, pulmonary diffusion capacity, pulmonary volumes
Muscle Protein Metabolism in the Elderly: Influence of Exercise and Nutrition
Authors: Tipton Kevin D.
Published: June 2009

Although the causes of sarcopenia are multi-factorial, at least some, such as poor nutrition and inactivity, may be preventable. Changes in muscle mass must be a result of net muscle protein breakdown over that particular time period. Stable isotope methodology has been used to examine the metabolic basis of muscle loss. Net muscle protein breakdown may occur due to a decrease in the basal level of muscle protein synthesis. However, changes of this type would likely be of small magnitude and undetectable by current methodology. Hormonal mediators may also be important, especially in association with forced inactivity. Net muscle protein breakdown may be also attributed to alterations in the periods of net muscle protein synthesis and breakdown each day. Reduced activity, combined with ineffectual nutrient intake, could lead to decreased net muscle protein balance. Chronic resistance exercise training clearly is an effective means of increasing muscle mass and strength in elderly individuals. Although sometimes limited, acute metabolic studies provide valuable information for maintenance of muscle mass with age. Key words: sarcopenia, inactivity, strength training, muscle protein synthesis, muscle hypertrophy
Effects of Physical Conditioning on Cardiac Autonomic Function in Healthy Middle-Aged Women
Authors: Myslivecek Paula R. , Brown C. Ann , Wolfe Larry A.
Published: June 2009

The purpose of this study was to determine whether moderate exercise training affects heart rate variability (HRV) and spontaneous baroreflex (SBR) function in healthy middle-aged women. Thirty-two sedentary women aged 40-59 yr were divided into four groups depending on reproductive state (premenopausal, PrM or postmenopausal, PoM, and training group (exercise or sedentary control group). The electrocardiographic R-R interval and systolic blood pressure (finger plethysmograph) were measured at rest during paced breathing at 16 breaths/min in the left lateral decubitus, sitting, and free standing postures, and during upright cycling at 40% maximal heart rate reserve (MHRR). After initial testing, the exercise groups underwent a 12 week walking program. After training, both exercise groups (PrM and PoM) had a longer R-R interval in all conditions, a higher SBR slope in the sitting and standing posture and lower sympathetic modulation in the standing posture, than the control groups and pre-training levels. During exercise, vagal modulation was higher and sympathetic modulation was lower in both exercise groups compared to pretraining values. Vagal modulation is increased following moderate intensity aerobic conditioning in middle-aged women. Key words: heart rate variability, spontaneous baroreflex function, exercise
The Role of O2 Supply in Muscle Fatigue
Authors: Hepple Russell T.
Published: June 2009

It is well established that altering O2 delivery to contracting skeletal muscle affects human performance. In this respect, a reduced O2 supply (e.g., hypoxia) increases the rate of muscle fatigue, whereas increasing O2 supply (e.g., hyperoxia) reduces the rate of fatigue. Interestingly, the faster onset of fatigue in moderate hypoxia does not appear to be a consequence of mitochondrial O2 limitation because these effects occur at submaximal rates of O2 consumption for these conditions and at O2 tensions well above that which impairs mitochondrial O2 uptake in vitro. Alterations in O2 supply modulate the regulation of cellular respiration and may affect the onset of impaired Ca2+ handling with fatigue. Specifically, changes in O2 supply alter the coupling between phosphocreatine hydrolysis and O2 uptake in contracting muscles, which by determining the rate of inorganic phosphate (Pi) accumulation may affect Ca2+ release. Partial ischemia differs somewhat in that the reduction in force could be due to reduced O2 supply and/or impaired removal of metabolic by-products secondary to insufficient blood flow. Nonetheless, recent evidence shows a parallel decline and restoration of force with alterations in O2 supply but not blood flow alone during submaximal contractions. Furthermore, the causes of fatigue are similar when O2 is plentiful and when it is reduced. Key words: muscular contractions, aerobic performance, hypoxia, hyperoxia, muscle bioenergetic
Muscle Fatigue: The Role of Metabolism
Authors: Mccully Kevin K. , Authier Bertrand , Olive Jennifer , Clark Bernard J.
Published: June 2009

This paper examined the role of metabolites in causing muscle fatigue. Previous studies have shown that Pi [Formula: see text] and H+ may be important factors in causing fatigue. A key question is the potential interaction between metabolic end-products and calcium related excitation-contraction coupling fatigue (ECC). An in vivo rat muscle model was used to measure tension development and metabolic end-products in response to electrical stimulation. Two stimulation protocols were used, high intensity stimulation followed by a medium intensity stimulation (High Group), and low intensity stimulation followed by a medium intensity stimulation (Low Group). Metabolic fatigue was based on concentrations of [Formula: see text] measured with phosphorus magnetic resonance spectroscopy. ECC fatigue was measured as the fatigue in excess of metabolic fatigue, and as the relative decline of force at low compared to high stimulation frequencies. During the initial stimulation period, the High Group had greater metabolic fatigue (p < 0.001) and greater ECC fatigue (p = 0.007). During the second stimulation period and recovery, the High Group had no difference in metabolic fatigue (p = 0.07) and greater ECC fatigue (p = 0.015). These results present a method for determining the relative amounts of metabolic and ECC fatigue, and suggest that metabolites can increase the amount of ECC fatigue. Key words: fatigue, skeletal muscle, excitation contraction coupling