bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐Temperature Synthesis of BiFeO3 via PVA Sol–Gel Route
Authors: Liu Ting , Xu Yebin , Zhao Jingyuan
Published: July 2010

Bismuth ferrite (BiFeO3) powders were synthesized by a sol–gel process using polyvinyl alcohol (PVA) as a complexing agent. Thermogravimetric, Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), and field‐emission scanning electron microscope techniques were used to characterize precursor and derived oxide powders. The effect of the ratios of positively charged valences to hydroxyl groups of PVA (Mn+/–OH) on the formation of BiFeO3 was investigated. XRD analysis showed that single‐phase and well‐crystallized BiFeO3 was obtained from the Mn+/–OH=2:1 precursor at a temperature as low as 400°C. For the precursor with Mn+/–OH=4:1, BiFeO3 formed only at the temperature of 600°C. With Mn+/–OH=1:1 and 1.5:1 precursor, pure BiFeO3 powder was not obtained. In present work, single‐phase BiFeO3 can be formed at lower temperature and less organics are required; furthermore, the process is simple and easy to control.
Compositional Dependence of Phase Formation Mechanisms at the Interface Between Titanium and Calcia‐Stabilized Zirconia at 1550°C
Authors: Chang Yao‐Wen , Lin Chien‐Cheng
Published: July 2010

ZrO2 samples with various CaO contents were fabricated by hot pressing, whereby CaO was dissolved by and/or reacted with ZrO2 to form a solid solution and/or CaZr4O9, respectively. After a reaction with Ti at 1550°C for 6 h in argon, the interfacial microstructures were characterized using X‐ray diffraction and analytical electron microscopy. Experimental results were very different from those found previously in the Y2O3–ZrO2 system. The 5 mol% CaO–ZrO2 sample was relatively stable due to the formation of a thin TiO layer acting as a diffusion barrier phase. However, α‐Ti(O), β′‐Ti (Zr, O), and/or Ti2ZrO were found in 9 or 17 mol% CaO–ZrO2 due to extensive interdiffusion of Ti, O, and Zr with a much thinner (β′‐Ti+α‐Ti) layer in 17 mol% CaO–ZrO2 than in 9 mol% CaO–ZrO2. Because CaO was hardly dissolved into Ti, it fully remained in the residual ZrO2, leading to the formation of spherical CaZrO3 in 9 mol% CaO–ZrO2 and columnar CaZrO3 in 17 mol% CaO–ZrO2. In the region far from the original interface, abundant intergranular α‐Zr was formed in 5 or 9 mol% CaO–ZrO2. Scattered α‐Zr and CaZrO3 were found in 17 mol% CaO–ZrO2 because a high concentration of extrinsic oxygen vacancies, which were created by the substitution of Ca+2 for Zr+4, effectively retarded the reduction of zirconia.
Submicrometer Grain‐Sized Transparent Erbium‐Doped Scandia Ceramics
Authors: Serivalsatit Karn , Ballato John
Published: July 2010

Erbium‐doped transparent Sc2O3 ceramics with an average grain size of 0.3 μm were synthesized from solution‐derived nanoparticles using a two‐step sintering process followed by hot isostatic pressing (HIP). The two‐step sintered ceramics showed a remarkable decrease in grain size with relative density over 98% before HIP. After HIP, the Sc2O3 ceramics became highly transparent, with negligible grain growth, and exhibited an optical transmittance of about 80%, nominally the Fresnel limit, for wavelengths greater than about 1.0 μm.
Enhanced Photocatalytic Disinfection of Escherichia coli Bacteria by Silver Modification of Nitrogen‐Doped Titanium Oxide Nanoparticle Photocatalyst Under Visible‐Light Illumination
Authors: Sun Caixia , Li Qi , Gao Shian , Cao Lihua , Shang Jian Ku , Shang Jian Ku
Published: July 2010

Enhanced photocatalytic disinfection of Escherichia coli (E. coli) bacteria under visible light illumination was achieved by a silver‐modified nitrogen‐doped titanium oxide (TiON/Ag2O) nanoparticle photocatalyst synthesized by a sol–gel process. In this photocatalytic material system, silver additives are beneficial to achieve better crystallization, larger surface area, higher pore volume, and enhanced visible light absorbance. The enhanced photocatalytic disinfection of E. coli by TiON/Ag2O was proven to be mostly attributed to the photocatalytic response of the TiON matrix and the subsequent coupling between TiON matrix and Ag2O nanoparticles, not the silver addition itself. The optimized silver modification concentration is determined at an Ag:Ti molar ratio of 1:50.
Influence of Scandinavian scientists in exercise physiology
Authors: Åstrand P.‐O.
Published: July 2010

The cradle of Scandinavian exercise physiology was in Copenhagen. Peter Ludwig Panum (1820‐1885) was head of a new physiological laboratory and his research included respiration, digestion and metabolism. Christian Bohr (1855‐1911) was his most prominent co‐worker and became his successor in 1885. Part of Bohr's training was in Leipzig, Germany, with Carl Ludwig, which led to his lifelong interest in problems of pulmonary exchange and blood transport of oxygen and carbon dioxide. He discovered the effect of carbon dioxide on the dissociation curve of hemoglobin (the Bohr effect). He attracted eminent young co‐workers, among them A. Krogh, V. Henriques and K. A. Hasselbalch (known for the Henderson‐Hasselbalch formula). One of his children, Niels Bohr, became one of the greatest modem nuclear physicists. We could name August Krogh as the father of exercise physiology in Scandinavia. This review will concentrate on some of his and his co‐workers' and students' scientific achievements up to the 1940s.
Fatigue effects of marathon running on neuromuscular performance
Authors: Nicol C. , Komi P. V. , Marconnet P.
Published: July 2010

Nine experienced endurance runners performed individual marathon runs that involved several tests of neuromuscular performance before, during and after the marathon. The tests were performed with special force platform and dynamometer techniques. The results showed an overall decrease in performance from the marathon. The maximal sprint velocity decreased parabolically during the marathon, reaching the final value of 84% of the pre‐marathon one. Similarly, the other test results after marathon indicated that maximal isometric knee extension torque was 78%, the performance in a special rebound test (drop jump) 84% and the 5‐jump performance 92% of the pre‐marathon values. These reductions were accompanied by alteration in the ground reaction force curves in the sprint and jump tests, suggesting reduced tolerance to stretch load as well as loss in the recoil characteristics of the muscles.
Etiology of gastrointestinal disturbances during endurance events
Authors: Brouns F.
Published: July 2010

Different types of upper and lower gastrointestinal (GI) symptoms occur in 30–50% of participants in endurance exercise. These symptoms may be related to more than one causal factor. When exercise is extremely intense or when dehydration causes hypovolemia, exercise induces changes in GI blood flow that may lead to local hypoxia of the GI tract and increased neural activity of the plexus submucosa of the gut. As a result, secretion of some gastroenteropancreatic hormones may be enhanced, and decreased absorption parallel with increased secretion may take place. Diarrhea, intestinal cramping, delayed gastric emptying and bleeding of the serosa of the stomach and colon may result. This bleeding may be aggravated by the use of anti‐inflammatory drugs. Exercise reduces GI tone and motility, and tends to delay transit. A reduction in tone may lead to reflux from the stomach or loose stools escaping from the colon. Gastric emptying is not influenced at moderate exercise intensities, but will be inhibited at maximal exercise intensities or during a state of dehydration. The latter likely induces a cascade of changes in hormone secretion and nervous output, leading to a change in absorption, secretion and gut motility. Additionally, severe emotional or mental strain may further influence GI functioning.
Nutritional evaluation of a sailing crew during a transatlantic race
Authors: Fogelholm G. M. , Lahtinen P. K.
Published: July 2010

Few studies describe the nutritional status of people in stressful situations and with limited access to food. We assessed the dietary intake and serum indices of nutritional status in a sailing crew (n= 14) during a transatlantic race and in a control group (n= 11 males). The crew's mean energy intake was 13.3 MJ/d. In both groups, the intake of retinol, thiamin, riboflavin, vitamin C, calcium and iron was sufficient but the intake of vitamin B6, magnesium and zinc rather low. In sailors, serum HDL cholesterol was higher before the race (1.61 mmol/l; 95% confidence interval: 1.44–1.69) than after it (1.34 mmol/l; 1.26–1.43). Serum calcium, potassium, magnesium, ferritin, zinc, and selenium concentrations did not indicate nutritional deficiency in either group.
Exercise function and biochemical properties of β‐adrenergic receptors of canine heart
Authors: Friedman D. B. , Adamick R. D. , Musch T. I. , Ordway G. A. , Williams R. S.
Published: July 2010

We tested the hypothesis that the biochemical properties of cardiac beta‐adrenergic receptors (βAR), as determined by standardin vitromethods, limit physiological responsiveness of dogs to PAR stimulation during peak exercise. Accordingly, we measured oxygen consumption, left ventricular dP/dt at 40 mmHg developed pressure, heart rate, and cardiac output during maximal dynamic exercise in 13 adult mongrel dogs. These studies were followed by biochemical analysis of PAR in membrane homogenates of left ventricle from the same animals using saturation binding and agonist competition curves for [125I] cyanopindolol. There was a substantial range in both biochemical and physiological variables within this population of normal dogs. However, there were no significant correlations between biochemical descriptors of cardiac PAR and any physiological variables measured during exercise. These results suggest that receptor‐effector coupling and maximal cardiac performance during intense sympathetic stimulation of peak exercise are limited by factors other than the biochemical properties of cardiac PAR.
The influence of low perceived soccer and social competence on later dropout from soccer: a prospective study of young boys
Authors: Ommundsen Y. , Vaglum P.
Published: July 2010

The main purpose of this prospective investigation was to examine the relationship of low perceived soccer and social competence with later dropout from soccer. Included in the analysis of these relationships was also the potential mediating influence of negative affect. A total of 223 12‐ to 16‐year‐old boys who played soccer in an organized league in Oslo were studied. The players were personally interviewed twice with an interval of 16 months. Results among the older players showed that low perceived soccer competence and low perceived peer popularity negatively influenced soccer persistence. Furthermore, in these relationship, low soccer enjoyment was a significant mediating factor. Findings obtained among the younger players demonstrated a direct negative effect of a low sense of interpersonal attraction and belongingness on soccer persistence. Whereas perceived soccer comptence was more influential than perceived social competence for persistence in soccer among the older players (14–16 years old), the opposite held for the younger group (12–13 years old). The results are generally consistent with the hypothesis that competence perception influences young people's affective state in achievement‐oriented activities which, in turn, influences their subsequent involvement in such activities.
Anabolic and catabolic hormonal response of elite runners to training at high altitude
Authors: Tsai L. , Pousette Å. , Carlström K. , Askenberger M. , Johansson C.
Published: July 2010

A 2‐week training period 2000 meters above sea level performed by 6 male elite Swedish runners influenced neither basal anabolic (total and non‐sex hormone‐binding globulin (SHBG)‐bound testosterone (NST) and insulin‐like growth factor‐1 (IGF‐1) nor catabolic (cortisol) hormones when comparing serum levels prior to and after the training camp. The anabolic vs catabolic hormone balance, expressed as the NST: cortisol ratio, also remained unchanged as well as SHBG and body mass. Thus, training at 2000 meters above sea level, often practised by elite runners to improve performance in competition at sea level, does not result in a catabolic situation after return to sea level, as measured by peripheral hormones. However, the adaptation to high altitude was associated with a slight (NS) decrease in testosterone as well as in anabolic vs catabolic balance as measured the third day at high altitude. Simultaneously, a decrease in subjective performance was claimed by the runners, but could not be shown by objective measurements. From day 3 to day 9 at high altitude, all runners claimed a subjective recuperation of performance. Total and non‐SHBG‐bound testosterone increased significantly from day 3 at high altitude to the first post‐camp sea‐level test. The results reflect the necessity of adaptation when travelling to races at different altitudes. The Swedish runners had significantly higher cortisol, total testosterone and NST levels compared with basal values of a group of 17 elite Kenyan runners living and training at high altitude. Since the NST cortisol and IGF‐1 values were not lower, a catabolic state or malnutrition was not likely to be present. The results might reflect an adaptation to altitude or ethnic variations.
Stress fracture of the tibia in athletes: diagnosis and natural course
Authors: Johansson C. , Ekenman I. , Lewander R.
Published: July 2010

The natural course of 46 stress fractures of the tibia were studied in relation to sports activity, diagnosis and treatment in 28 recreational athletes and 13 elite athletes. Two major types of stress fractures were observed. Thirty athletes sustained a posteriomedial fracture of the tibia and claimed a sudden onset of exertional pain. The initial symptoms occurred during running or orienteering (n= 19), soccer (n= 4), workout or dancing (n= 3), triathlon, basketball, badminton and tennis (one each) and were similarity distributed between left and right leg. Scintigraphs showed Zwas type I/II lesions, while X‐rays were negative in most cases. The patients were treated only with restriction in sports activities. The fractures healed within 8–24 weeks with excellent or good results. The remaining 11 athletes had anterior margin stress fractures with a slow onset of exertional pain and a long delay in diagnosis. These injuries occurred in 4 long‐distance runners, 2 handball players, 2 dancers, 1 volleyball player, 1 triathloner and 1 decathloner. They were located in the nondominant left leg (in three cases bilateral). The fractures showed Zwas I or II lesions on scintigrams, but differed from the posteriomedial injuries on the typical V‐shape appearence on X‐ray. The patients had conservative treatment, including immobility and restriction in sports activities. Four of the patients were operated when not symptom‐free after 12–34 months. All elite athletes (n= 5) in this group had to interrupt then‐elite carreer. At follow up 24–60 months after the initial symptoms, only 1 patient was symptom‐free. Thus, posteriomedial tibial stress fractures show a sudden onset and benign natural course, while anterior stress fractures should be treated with caution. The use of bone scintigraphy should be emphasized early when an athlete presents with exertional lower leg pain.
Decreased eccentric muscle endurance in the conservatively treated anterior cruciate‐deficient knee
Authors: Engström B. , Westblad P. , Johansson C.
Published: July 2010

Concentric (CON) and eccentric (ECC) isokinetic knee extensor endurance, during 100 repetitive isokinetic contractions, were analysed in 32 consecutive patients with conservatively treated unilateral anterior cruciate ligament ruptured knees. There were 20 men and 12 women (mean age 34 years). The test was performed 6.8 years after the injury (range 4–14). The uninjured leg in each patient served as control. Lysholm subjective score, Tegner activity score and IKDC grading were used to relate the subjective knee function to muscle performance. Knee extensor endurance for concentric as well as for eccentric contractions were significantly lower in the injured side than the uninjured side. The magnitude of decrease in muscle performance was 7.6% for concentric (range‐12 to 27%) and 15.3% for eccentric (range ‐9 to 50%) endurance. The eccentric injured/uninjured endurance ratio correlated significantly to the Lysholm subjective score. We conclude that the knee extensor endurance is decreased in patients with conservatively treated anterior cruciate ligament‐ruptured knees. The eccentric endurance test seems to reflect the patients' subjective knee functioning.
The crisis of Soviet sports: organizational and legal problems
Authors: Uvarov V.
Published: July 2010

The aim of the investigation is to elaborate a model of sports management and legal regulation of sport based on the principles of democracy and the sovereign rights and independence of the republics of the former Soviet Union. This article uses a functional, systematic and sociological approach, examines formal juridical methods and the comparative science of law and uses survey questionnaires and interviews with sports administrators. The concept of sports management and legal regulation of sport at a time of the creation of the Commonwealth of Independent States involves: the development of sport ‐ its function as a social necessity; the enhanced responsibility and role of the state in promoting sport; determining the functions of sports management bodies; mastering economic methods of sports management; and forming new sports legislation. All these factors enable the creation of management procedures and legal regulation that will contribute to extricating sport from the deep crisis in which it finds itself in a disintegrating society, to raising its prestige in society and to enabling sport to function under the conditions of economic reform and transition to market relations.
Effects of early cryotherapy in experimental skeletal muscle injury
Authors: Hurme T. , Rantanen J. , Kaliomo H.
Published: July 2010

The effects of early cryotherapy on healing of rat gastrocnemius muscle injury were investigated in schedules similar to those in clinical use. After the treatment: (1) hematoma between ruptured myofiber stumps was smaller and (2) extravasation of inflammatory cells to the injury site and (3) activation of satellite cells to myotubes and mature myofibers were delayed. Early proliferation of granulation tissue was not altered. Thus, cryotherapy affected the time‐table of the healing process rather than causing qualitative differences. No negative side effects of cryotherapy were found. Positive effects of cryotherapy in clinical practice most likely depend on factors other than those involved with actual regeneration of the muscle lesion, such as reducing muscle spasms, which can cause reruptures, and analgesia allowing early mobilization. The results support the current clinical practice of treating acute muscle fiber ruptures with initial cold application followed by active early mobilization.
Meniscal resection in the athlete's knee
Authors: Faunø P. , Nielsen A. B.
Published: July 2010

In a retrospective study, the consequences of arthroscopic meniscal resection in athletes with stable knees were analyzed. We found that 36% had been obliged to reduce or quit their sport activity 8.6 years after surgery. The risk factors associated with reduced sport ability were meniscal lesions other than the bucket‐handle type, high age and involvement in ball games. Competitive athletes were not more at risk than recreational athletes. Forty‐nine percent had at least one sign of arthrosis in the operated knee. More than one sign of Fairbank's degenerative changes were associated with reduced sports performance.
Pre‐heel‐strike peroneal muscle activity during walking and running with and without an external ankle support
Authors: Konradsen L. , Højsgaard C.
Published: July 2010

The electromyographic activity of the peroneus longus and brevis muscles was recorded during 100 strides of walking and running on a treadmill in 9 experienced runners with and without an inversion restricting external ankle support. The duration of peroneal activity in the stance phase increased from median 61% of this stage when jogging to 88% when running fast. Pre‐heel‐strike activity was present in median 10% of all strides when walking, in 28% when jogging, in 40% when running at a medium pace and in 45% when running fast. Application of an external ankle support reduced pre‐heel‐strike activity by 50% for jogging and medium‐pace running. Our results suggest that an unacceptable degree of inversion of the ankle/foot complex in late swing phase produces a stimulus for peroneal muscle contraction before the foot is loaded at heel‐strike.
A three‐dimensional crisis‐related analysis of perceived coach's behavior in competition
Authors: Bar‐Eli M. , Tenenbaum G. , Levy‐Kolker N.
Published: July 2010

Perceived coach's behavior in competition is analyzed in terms of a coach's positive, negative, or lack of response, which expectedly or unexpectedly follows a player's successful or unsuccessful action or is independent of player's action. The perceived contribution of these variables to extreme psychological arousal states (crisis, noncrisis) was investigated. Thirty‐seven elite ball‐game players estimated the occurrence probability of all Bayesian combinations among these variables under crisis and noncrisis conditions. Under crisis, a negative response, an unsuccessful action and unexpected events were more probable, whereas under noncrisis, the reverse is true. The athlete's psychological state was related particularly to the coach's response. The results are discussed theoretically in reference to the crisis construct.
Creatine supplementation and dynamic high‐intensity intermittent exercise
Authors: Balsom P. D. , Ekblom B. , Söerlund K. , Sjödln B. , Hultman E.
Published: July 2010

Two intermittent high‐intensity exercise protocols were performed before and after the administration of either creatine or a placebo, and performance characteristics and selected physiological responses were studied. Each exercise protocol consisted of 10 6‐s bouts of high‐intensity cycling at 2 exercise intensities (130 rev/min [EX130]: ∼820 W and 140 rev/min [EX140)]: ∼ 880 W) so that in EX130 the same amount of exercise was performed before and after the administration period, whereas an exercise intensity in EX140 was chosen to induce fatigue over the 10 exercise bouts. Sixteen healthy male subjects were randomly assigned to the 2 experimental groups. A double‐blind design was used in this study. There were no significant changes in the placebo group for any of the measured parameters. Performance towards the end of each exercise bout in EX140 was enhanced following creatine supplementation, as shown by a smaller decline in work output from baseline along the 10 trials. Although more work was performed in EX140, after vs before the administration period, blood lactate accumulation decreased (mean and SEM), from 10.8 (0.5) to 9.1 (0.8) mmol·l−1 and plasma accumulation of hypoxanthine decreased from 21.1 (0.4) to 16.7 (0.8) μmol·l−1, but there was no change in oxygen uptake measured during 3 exercise and recovery periods [3.18 (0–1) vs 3.14 (0.1) l·min−1]. In EX130 blood lactate accumulation decreased, from 7.0 (0.5) to 5.1 (0.5) mmol·l−1, and oxygen uptake was also lower, decreasing from 2.84 (0.1) to 2.78 (0.1) l·min−1. A significant increase in body mass (11 kg: range 0.3 to 2.5 kg) was found in the creatine group. The mechanism responsible for the improved performance with creatine supplementation are postulated to be both a higher initial creatine phosphate content availability and an increased rate of creatine phosphate resynthesis during recovery periods. The lower blood lactate and hypoxanthine accumulation can also be explained by these mechanisms.
Eating disorders and associated symptoms among adolescent Swimmers
Authors: Rosenvinge J. H. , Vig C.
Published: July 2010

The article reports on two studies investigating the frequency of eating disorders among swimmers. The first study was a screening based on self‐report only and the second was a controlled study with a clinical interview of alle subjects. In the screening study, 28% of men and 3.5% of women had suspected eating disorder symptoms. No significant relationship was found between risk levels and competitive levels. In the controlled study, no indications of anorexia nervosa were found. Among Swimmers, 3.2% satisfied the DSM‐III‐R criteria for bulimia nervosa, and 9.7% had partial bulimic conditions. The results did not support the hypothesis of an increased frequency of clinical or partial eating disorders in elite athletes. The presence of symptoms was more related to being a woman rather than being a swimmer. Suggestions for further research are outlined to determine the causal relationship between sports and eating disorders.
Proceedings of the First Scandinavian Congress in Sports Medicine, Oslo, Norway, November 5–8, 1992
Authors: Ekeland Arne
Published: July 2010

The First Scandinavian Congress in Sports Medicine was arranged by the Norwegian Society of Sports Medicine, the Norwegian Society of Sports Physiotherapy and the Scandinavian Foundation for Medicine & Science in Sports, to increase the exchange of science in sports medicine in Scandinavia. The Congress assembled almost 600 participants, who were offered a series of guest lectures from distinguished researchers, several symposia, instructional courses and free paper sessions. The second Scandinavian Congress in Sports Medicine will be held in Copenhagen in 1994.
Training, injuries and infections among elite orienteers
Authors: Johannsen F. , Stallknecht B.
Published: July 2010

Three years of registration of training, injuries, infections and stretching behaviour among national class orienteers is presented. Twenty‐three runners were included for a 1‐ to 3‐year period. Twenty‐eight male‐years and 27 female‐years were analysed. A total of 219 injuries and infections were registered: 55 (25%) acute injuries, 71 (32%) overuse injuries and 93 (42%) infections. Overuse injuries were found to be the major problem, as these injuries affected training for an average of 35 days per runner per year, compared with 7 days caused by acute injuries and 10 days caused by infections. The acute injuries were mainly direct traumas and ankle distorsions. Overuse injuries affecting die knee region were the most numerous, but rear foot injuries affected training the most. An increase in training load was found in the last weeks before overuse injuries and infections. Stretching could not be found to prevent injuries.
Changes in physical activity, maximal isometric strength and maximal oxygen uptake from late teenage to adulthood: an eight‐year follow‐up study of adolescents in Denmark
Authors: Andersen L. B. , Haraldsdóttir J.
Published: July 2010

A randomly selected group of 88 men and 115 women, aged 23–27 years in 1991, were tested as teenagers in 1983, and then followed‐up in 1991. A mean increase of 15% in maximal voluntary isometric strength was found in men, and no change was found in women over the 8 years. Body weight increased 14% in men and 6% in women. Strength in relation to body weight (N · kg−1) did not change in men, but a small decrease of 3% was found in women. Strength in abdominal muscles decreased in blue‐collar workers but increased in students. Maximal oxygen uptake (V̇o2max (ml · min−1kg−1) decreased 9% in men and 3% in women. The values in 1991 were 47.9 and 39.5 ml · min−1kg−1 for men and women, respectively. Participation in leisure sport activities decreased 1.7 h · week−1 in men and 1.2 h · week−1 in women. Seventy percent of the men and 74% of the women participated in regular leisure sport activity, which was a marked increase from 8 years before, when only 54% of the men and 57% of the women were similarly active. The overall decrease in V̇O2max in men was due primarily to a decrease among blue‐collar workers and unemployed men: 19%vs 4% in other occupational groups. Only 20% of the blue‐collar workers participated in sport activities for more than 4 h · week−1, and 47% did not participate at all. In women, changes in strength and V̇O2max were related to motherhood. Abdominal muscle strength decreased, but arm flexor strength increased in women who had become mothers. V̇O2max decreased 14% in mothers vs 2% in other women. Changes over 8 years in V̇O2max and strength did not relate to changes in physical activity, but a significant relationship between decrease in physical activity and gain in body fat was found in men. Changes in body weight and body fat were the only variables that correlated with changes in strength. None of the observed changes related to changes in V̇O2max (ml · min−1kg−1). For the 23‐ to 27‐year‐olds, the level of physical activity assessed in h · week−1 was almost as high in women as in men.
Changes in physical activity level and risk of ischaemic heart disease
Authors: Hein H. O. , Suadicanl P. , Sørensen H. , Gyntelberg F.
Published: July 2010

The aim of this study was to analyse prospectively the impact of changes in physical activity level on the risk of ischaemic heart disease (IHD). In 1970–1971, 5249 men aged 40–59 years (mean=48) reported their level of physical activity in leisure time. In 1985–1986, a new baseline was established comprising 75% of survivors who reported their level of physical activity at the time. Some 2894 men aged 53–75, mean=63, free from arteriosclerotic stigmas were included, and their morbidity and mortality were recorded over the next 6 years. Some 181 men had an IHD event; 44 were fatal. A total of 270 men died from all‐cause mortality (ACM). Men physically active less than 4 h per week in 1970–1971 had an increased risk of IHD, RR (95% confidence interval)=1.7 (1.1‐2.6) compared with men physically more active. For men who reported a sedentary lifestyle, the 1985–1986 RR of IHD was 1.1 (0.9‐1.5) compared with more active men. Potential confounders did not explain the results. Among the younger half, those who changed from sedentary to active had a decreased risk of IHD compared with those who remained sedentary (RR=0.6 (0.1‐2.5)). In older men, those who changed from sedentary to active had an increased risk of IHD compared with those who remained sedentary (RR=1.9 (0.9‐4.2)). In the 6‐year follow‐up period, the lowest risk of IHD and ACM was found in men who were physically active when reaching midlife and continued to be active. In the younger age group, 40–49 years, taking up a more active lifestyle during the next 15 years was associated with a reduction in the incidence of IHD. In the older age group, 50–59 years, changing from a sedentary to a physically more active lifestyle during the next 15 years was associated with a doubled risk of IHD during the 6‐year follow‐up period compared with men at the same age who continued to be sedentary. Consequently, we advocate a thorough medical check‐up before advising more physical activity in elderly men.
Trends of health‐related physical activity in Finland: 10‐year follow‐up of an adult cohort in eastern Finland
Authors: Oja P. , Miilunpalo S. , Vuori I. , Pasanen M. , Urponen H.
Published: July 2010

The health‐related physical activity of Finns was studied during the 1980s by analysing changes in activity in a 10‐year follow‐up of a representative population cohort aged 20–65 years at the onset of the study. The proportion of apparently healthy people exercising at least twice a week for fitness and health increased from about 40% to over 50%. The increase was particularly large among women and young people. Occupational physical activity, education and marital status did not affect the trends. In contrast, regular vigorous exercise remained unchanged. These findings are consistent with other observations showing a steady increase in health‐related physical activity among adult Finns during the past 20 years. However, in terms of the health potential of exercise, a majority of the population remains less than optimally active.
Quantification of anaerobic capacity
Authors: Gastin P. B.
Published: July 2010

Anaerobic capacity may be defined as the maximal amount of ATP formed by the anaerobic processes during a single bout of maximal exercise. While several methods have been presented to measure a person's anaerobic capacity, none have become universally accepted. The muscle biopsy technique provides information on the anaerobic energy release from direct measures of ATP and CP breakdown and muscle lactate concentrations. As a practical measure of anaerobic capacity, the method may be limited, as it is an invasive, skilled technique. Furthermore, it has the limitation of measuring relative changes in concentrations, not amounts, such that the anaerobic contribution is estimated from estimates of the active muscle mass involvement. Measurement of lactate in blood after exhaustive exercise has frequently been used, but several factors suggest that, while it provides an indication of the extent of anaerobic glycolysis, it cannot be used as a quantitative measure of the anaerobic energy yield. The mean power during an all‐out effort on a bicycle ergometer has also been assumed to be a measure of anaerobic capacity, yet it provides only an indication of the ability to maintain high power outputs. Concerns over the duration of the test, the protocol and type of ergometer used and the contribution of the aerobic energy system to the energy supply also limit its validity as a measure of anaerobic capacity. The oxygen debt, defined as the recovery oxygen uptake above resting metabolic rates, has been discredited as a valid and reliable measure of the anaerobic capacity, as it is generally acknowledged that mechanisms other than the metabolism of lactate also contribute to the post‐exercise oxygen uptake. The recent work of Medbø et al. in re‐examining the issue of oxygen deficit has created considerable interest in its use as a measure of anaerobic capacity. The measurement of oxygen deficit directly depends on the accurate assessment of the energy cost of the work completed. This is not difficult during submaximal exercise, as the steady‐state oxygen uptake represents the energy costs. During exhaustive supramaximal exercise, the validity of the maximal accumulated oxygen deficit as a measure of the anaerobic capacity has been questioned, as the energy cost is estimated and not measured, either by assuming a given mechanical efficiency or by extrapolating the submaximal relationship between work intensity and oxygen uptake to supramaximal levels. Despite these theoretical objections, the maximal accumuiated oxygen deficit method remains a promising measure of the anaerobic capacity, as it provides a non‐invasive means of quantifying the anaerobic energy release during exhaustive exercise.
Physical training, growth hormone and testosterone levels and blood pressure in prepubertal, pubertal and adolescent boys
Authors: Zakas A. , Mandroukas K. , Karamouzis G. , Panagiotopoulou G.
Published: July 2010

The purpose of this study was to determine the resting values of growth hormone (GH) and testosterone (T) within prepubertal, pubertal and adolescence ages and to compare the effects of physical training in each age, in 2 groups. The exercise group (A) consisted of 10 ten‐year‐old boys, 10 thirteen‐year‐old boys and 9 sixteen‐year‐old boys. The control group (B) consisted of approximately the same number of subjects of the same ages. Group A, in addition to the school activity, trained with intervals (3 months, 50 mid/day, 3 days/week). at high intensity (80–85% of max) and at light intensity (30–40% of max). Group B participated only in the school physical education program 2–3 times/week. Venous blood samples were taken at rest by intravenous catheter before and after training. Levels of GH and T in blood serum was determined by radioimmunoassay. Before training, the levels of T differed between the 3 ages, but there were no significant differences in GH (group A and B). After training, the levels of GH and T in group A were significantly higher in the 13‐year‐old boys and in the 16‐year‐old boys, but were unchanged in the 10‐year‐old boys. In group B the levels of GH and T were unchanged in all 3 ages. The conclusion is that neither high nor mild intensity training can change the levels of GH and T in prepubertal boys. However, high intensity training can be a stimulus for increasing GH and T levels in puberty and adolescence
Longitudinal variations in bronchial responsiveness in cross‐country skiers and control subjects
Authors: Heir T.
Published: July 2010

Longitudinal variations in bronchial responsiveness to methacholine was studied in 19 male crosscountry skiers 19–21 years old during the season of their sport and compared with the response in 22 age‐matched control subjects with minimal physical activity. The methacholine concentration required for a 10% fall in the forced expiratory volume in the first second (PC10) remained stable from August to November in the group of skiers, then decreased from November to February and finally increased from February to June. In the control group, PC10 increased from August to November, increased further to February and finally decreased from February to June. Alternative methods for expressing bronchial responsiveness as the linear dosc‐response slope or the logarithmic dose‐response slope gave no more information than did PC10 alone. High correlations were found between PC10 and either of the dose‐response slopes. PC10 and the dose response‐slopes were equally reproducible when measured on two successive days. In contrary to the control group, high‐performance cross‐ country skiers demonstrated increased bronchial responsiveness in the winter. The PC10 was an advantageous method for studying longitudinal changes in bronchial responsiveness among healthy subjects.
Blood sampling during continuous running and 30‐second intervals on a treadmill
Authors: Gullstrand L. , Sjüdin B. , Svedenhag J.
Published: July 2010

The aim of the study was to investigate whether results from lactate threshold tests on a treadmill would be influenced by collecting blood during 30‐s intervals (INT) as compared to sampling during continuous running (CONT). Ten well‐trained middle‐ and long‐distance runners ran the two protocols randomly on separate days, with the same speed both times. Values of blood lactate, heart rate and ratings of perceived exertion (RPE) were compared. The results showed no significant difference in any of the variables comparing the two regimens. During CONT and INT, running speed at 4.0 mmol · l−1 was 18.6 (±1.2) and 18.7 (±1.2) km · h−1, HR 182 (±10.7) and 183 (±8.1) beats · min−1, respectively. Also at the 2 and 3 mmol · l−1 level there were no significant differences in running speed or heart rate. RPE values of legs and breathing at the final speed, just above the 4 mM level, showed no significant difference. It is concluded that, for well‐trained middle‐ and long‐distance runners, any of the two regimens can be chosen without affecting the lactate threshold results.
Surgical treatment of medial tibial stress syndrome (shin splint) by fasciotomy of the superficial posterior compartment of the leg
Authors: Holen K. J. , Engebretsen L. , Grøntvedt T. , Rossvoll I. , Hammer S. , Stoltz V.
Published: July 2010

From September 1988 to June 1990, 35 athletes were treated for medial tibial stress syndrome (shin splint) by fasciotomy of the superficial posterior compartment of the leg. Thirty‐two patients were available for the follow‐up, including self‐assessment, clinical examination and activity scoring. The mean postoperative observation time was 16 months. Thirteen patients were performing sports at top international or top national level; 19 patients were competing at different lower levels. Twenty‐three patients improved, 7 were unchanged and 2 had poor results.
Injuries in national karate competitions in Finland
Authors: Tuominen R.
Published: July 2010

The injuries sustained in 6 national karate competitions in Finland were studied by analyzing data from 450 bouts during the season 1991–1992. The analyzed data included a personal interview with each competitor and detailed information on the bouts and any injuries sustained. The overall probability of injury was 0.28 per bout. These injuries occurred to 16% of the 647 competitors. Occurrence of injury was greatest among adult men, which was pronounced in final bouts. Of all injuries diagnosed by the physicians for the competitions, more than 95% were localized to the head. The majority of these were minor injuries. Experienced competitors were more injury‐prone than beginners. On the other hand, none of the background factors studied significantly affected the probability of injuring one's opponent. Most injuries and penalties, as well as full scores, were caused by direct punches to the head. From these findings it was concluded that a protective guard for the head together with modification of competition rules could significantly reduce injuries.
A maximal cycle exercise protocol to predict maximal oxygen uptake
Authors: Andersen L. B.
Published: July 2010

Maximal oxygen uptake (VO2max) was predicted from maximal power output (MPO) in a progressive cycle ergometer test. The subjects were 232 men and 303 women 15–28 years of age. The relationship between VO2max and MPO was: V O2max (1 · min−1) = 0.16 + (0.0117 × MPO) (w). A correlation coefficient of r= 0.88 was found between MPO and VO2max. Test‐retest reliability was evaluated by two procedures. Standard deviations of test‐retest differences in MPO and VO2max using the same standardized procedure in 35 subjects, were 10% and 8%, respectively, and Pearson correlations between test and retest values were 0.95 and 0.96, respectively.

When MPO of tests conducted at the schools was compared to a standardized test performed by a physiologist in 267 subjects, test‐retest Pearson correlation was 0.82. A prediction model only including MPO and explaining 80% of the variability in VO2max, is suggested for use in healthy adolescents and young adults.
Patellofemoral pain syndrome in young women
Authors: Thomeé R. , Renström P. , Karlsson J. , Grimby G.
Published: July 2010

Muscle function was evaluated in 40 patients with patellofemoral pain syndrome (PFPS) and 20 healthy controls. Patients with PFPS had a significantly lower knee extensor strength in the most symptomatic knee compared to the least symptomatic knee. Further, the patients had less vertical jumping ability and were weaker in the most symptomatic knee compared to the controls, with the largest differences in eccentric knee extension. There were lower strength and EMG activity, in the patients compared to the controls, in the range closer to full extension and significant differences in muscle activity between the vastus medialis and the rectus femoris muscle. The results can be explained by inhibition selective to knee angles and to the vastus medialis muscle.
Sudden death and physical activity in athletes and nonathletes
Authors: Jensen‐Urstad M.
Published: July 2010

Among young athletes, sudden deaths are predominantly associated with cardiomyopathies, coronary artery abnormalities and myocarditis, but coronary heart disease is a reality already in this group. The absolute risk of sudden death is, however, low and the benefits of routine medical screening are small. If an athlete has had any symptoms that arouse suspicion of cardiac disease, the athlete must be meticulously investigated, as an underlying life‐threatening illness may be present. Among all nonathletes, as well as athletes ≥30 years, the predominant cause of sudden death is coronary heart disease. A large number of studies have provided strong evidence suggesting the benefits of physical activity regarding prevention of cardiovascular death and disease. The immediate risk for sudden death is higher during physical activity than during other times, especially among usually sedentary individuals, but inactivity is much more dangerous in the long run. Regular exercise at moderate intensity gives large benefits with small risks. The benefits of irregular and intensive exercise are less clear and the risks higher. For the individual without known heart disease who exercises regularly, the risk for sudden death during physical activity is extremely small.
Do adolescents and parents report each other's physical activity accurately?
Authors: Anderssen N. , Jacobs D. R. , Aas H. , Jakobsen R.
Published: July 2010

In research concerning socialization into sports there is a need to assess children's reports of parental physical activity. Reports by young adolescents and their parents of each other's leisure‐time physical activity and related issues were compared with self‐reported measures. A total of 755 family units in western Norway, consisting of 755 13‐year‐olds, mean age 13.3±0.3 years (425 boys, 330 girls, 644 fathers and 732 mothers) completed a self‐administered physical activity questionnaire. Pearson's r between self‐reports by parents and the reports by their children varied between 0.56 (P<0.001) and 0.07 (nonsignificant). Pearson's r between off‐springs' self‐reported physical activity and reports by their parents varied between 0.41 and 0.55 (P<0.001). The results support cautious use of young adolescents' reports of parental physical activity.
Injuries in windsurfing due to foot fixation
Authors: Witt J. , Paaske B. P. , Jørgensen U.
Published: July 2010

Two cases are reported: a 27‐year‐old man fractured the lower leg and an 18 year‐old man sustained a rupture of the anterior cruciate ligament and medial collateral ligament during windsurfing. Both injuries may be ascribed to the fact that the patients' feet were fixed in footstraps and that their legs were twisted during the fall. Footstraps evidently represent a hazard, and action should be taken towards solving this problem. We suggest that either the footstraps be fitted with a release mechanism or surfers avoid using them.
Viscoelastic response to repeated static stretching in the human hamstring muscle
Authors: Magnusson S. P. , Simonsen E. B. , Aagaard P. , Gleim G. W. , McHugh M. P. , Kjaer M.
Published: July 2010

The purpose of this study was (1) to evaluate the reproducibility of a new method of measuring passive resistance to stretch in the human hamstring muscle group, in vivo, using a test re‐test protocol and 2) to examine the effect of repeated stretches. Passive resistance offered by the hamstring muscle group during knee extension was measured in 10 subjects as knee flexion moment (Nm) using a KinCom dynamometer. The knee was passively extended at 5 deg/s to the final position where it remained stationary for 90 s (static phase). EMG of the hamstring muscle was also measured. The test re‐test protocol included 2 tests (tests 1 and 2) administered 1 h apart. On a separate occasion 5 consecutive static stretches were administered (stretches 1–5) separted by 30 s. Stretch 6 was administered one hour after stretch 5. In the static phase passive resistance did not differ between test 1 and test 2. Resistance declined in both tests 1 and 2, whereas EMG activity remained unchanged. The decline in resistance was significant up to 45 s. For the repeated stretches there was an effect of time (90 s) and stretch (1–5) with a significant interaction i.e., resistance diminished with stretches, and the 90‐s decline was less as more stretches were performed. Passive resistance in stretch 6 was lower than in stretch 1. The present study has demonstrated a reliable method for studying resistance to stretch of the human hamstring muscle group. A viscoelastic response of the human hamstring muscle was shown. With 5 repeated stretches, resistance to stretch diminished and each stretch exibited a viscoelastic response, albeit less with each subsequent stretch. The effect of 5 repeated stretches was significant 1 h later.