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Showing papers in "Scandinavian Journal of Medicine & Science in Sports in 2005"


Journal ArticleDOI
TL;DR: Regression analysis revealed that RPE obtained during exercise could account for ∼29% of the variance in the improvement in exercise performance and this may partly explain the subsequent ergogenic effects of caffeine on performance.
Abstract: The purpose of this study was to use the meta-analytic approach to examine the effects of caffeine ingestion on ratings of perceived exertion (RPE) Twenty-one studies with 109 effect sizes (ESs) met the inclusion criteria Coding incorporated RPE scores obtained both during constant load exercise (n=89) and upon termination of exhausting exercise (n=20) In addition, when reported, the exercise performance ES was also computed (n=16) In comparison to placebo, caffeine reduced RPE during exercise by 56% (95% CI (confidence interval), -45% to -67%), with an equivalent RPE ES of -047 (95% CI, -035 to -059) These values were significantly greater (P<005) than RPE obtained at the end of exercise (RPE % change, 001%; 95% CI, -19 to 20%; RPE ES, 000, 95% CI, -017 to 017) In addition, caffeine improved exercise performance by 112% (95% CI; 46-178%) Regression analysis revealed that RPE obtained during exercise could account for approximately 29% of the variance in the improvement in exercise performance The results demonstrate that caffeine reduces RPE during exercise and this may partly explain the subsequent ergogenic effects of caffeine on performance

445 citations


Journal ArticleDOI
TL;DR: The molecular mechanisms involved in the aging of collagen and consequent increase in mechanical strength and stiffness occur in a series of enzymic and non‐enzymic intermolecular cross‐links.
Abstract: The molecular mechanisms involved in the aging of collagen and consequent increase in mechanical strength and stiffness occur in a series of enzymic and non-enzymic intermolecular cross-links. The enzymic mechanism involves divalent aldimine intermolecular cross-links derived from the reaction of aldehydes which then mature to trivalent cross-links and further stabilize the collagen fiber and is now well known. Recent studies have demonstrated that the rate of turnover and level of telopeptide lysyl hydroxylation modifies the nature of the cross-link and hence the mechanical strength of the fiber. The slow turnover of mature collagen subsequently allows accumulation of the products of the adventitious non-enzymic reaction of glucose with the lysines in the triple helix to form glucosyl lysine and its Amadori product, that is, the Maillard reaction. These products are subsequently oxidized to a complex series of advanced glycation end-products, some of which are intermolecular cross-links between the triple helices rendering the fiber too stiff for optimal functioning of the collagen fibers, and consequently of the particular tissue involved. The glycation reactions following maturation are true aging processes, and attempts at their specific inhibition involve competitive inhibition of the Maillard reaction and chemical cleavage of the glycation cross-links. It is clear that the nature of the age-related cross-links and hence tissue strength depends on the rate of turnover of the collagen. An examination of the particular effect of strenuous exercise on the rate of turnover of collagen and hence cross-linking in different tissues could lead to a better understanding of optimal sports training regimes.

235 citations


Journal ArticleDOI
TL;DR: The purpose of this study was to study the risk for injury and injury pattern in Swedish male elite football and to compare two different injury definitions and no significant difference for injury between tissue injuries and time‐lost injuries was found.
Abstract: The purpose of this study was to study the risk for injury and injury pattern in Swedish male elite football and to compare two different injury definitions. A prospective cohort study was conducte ...

235 citations


Journal ArticleDOI
TL;DR: The physiological responses associated with the diving response, its functional significance, and its cardiorespiratory control are outlined and it is suggested that future research should be focused towards understanding the role of altered ventilatory responses in human breath‐hold athletes as well as in patients suffering from sleep‐disordered breathing.
Abstract: The purpose of this review is to outline the physiological responses associated with the diving response, its functional significance, and its cardiorespiratory control. This review is separated into four major sections. Section one outlines the diving response and its physiology. Section two provides support for the hypothesis that the primary role of the diving response is the conservation of oxygen. The third section describes how the diving response is controlled and provides a model that illustrates the cardiorespiratory interaction. Finally, the fourth section illustrates potential adaptations that result after regular exposure to an asphyxic environment. The cardiovascular and endocrine responses associated with the diving response and apnea are bradycardia, vasoconstriction, and an increase in secretion of suprarenal catecholamines. These responses require the integration of both the cardiovascular system and the respiratory system. The primary role of the diving response is likely to conserve oxygen for sensitive brain and heart tissue and to lengthen the time before the onset of serious hypoxic damage. We suggest that future research should be focused towards understanding the role of altered ventilatory responses in human breath-hold athletes as well as in patients suffering from sleep-disordered breathing. A lack of oxygen even for short periods can be detrimental to most birds, mammals, and humans. However, many diving birds, mammals, and humans have adapted to endure hypoxia or anoxia for extended periods (Hermes-Lima & Zenteno-Savin, 2002). The major physiological adaptation allowing animals to endure the lack of oxygen during apnea is the diving response. The diving response has been demonstrated across a variety of diving birds, mammals (Butler & Jones, 1997), and humans (Hong, 1989). It is qualitatively similar between species and involves both bradycardia and peripheral vasoconstriction triggered in response to respiratory arrest (Daly, 1997) and stimulation of facial cold receptors (Elsner & Gooden, 1983). For the purpose of this review, we will use the following terms: diving response, apnea, and face immersion and define them as follows. The diving response is a reduction in heart rate because of an increase in cardiac parasympathetic nerve activity, peripheral vasoconstriction on the arterial vascular tree, and an increase in sympathetic activity triggered in response to the cessation of respiration and, but not necessarily including, the stimulation of facial cold receptors. We will refer to the cessation of respiration as apnea and the stimulation of facial cold receptors by water will be referred to as face immersion. The human diving response involves bradycardia (Asmussen & Kristiansson, 1968), vasoconstriction

228 citations


Journal ArticleDOI
TL;DR: The Danish and Swedish male top football divisions were studied prospectively from January to June 2001 to compare exposure to football and injury incidence, severity and distribution.
Abstract: The Danish and Swedish male top football divisions were studied prospectively from January to June 2001. Exposure to football and injury incidence, severity and distribution were compared between the countries. Swedish players had greater exposure to training (171 vs. 123 h per season, P<0.001), whereas exposure to matches did not differ between the countries. There was a higher risk for injury during training in Denmark than in Sweden (11.8 vs. 6.0 per 1000 h, P<0.01), whereas for match play there was no difference (28.2 vs. 26.2 per 1000 h). The risk for incurring a major injury (absence from football more than 4 weeks) was greater in Denmark (1.8 vs. 0.7 per 1000 h, P = 0.002). The distribution of injuries according to type and location was similar in both countries. Of all injuries in Denmark and Sweden, overuse injury accounted for 39% and 38% (NS), and re-injury for 30% and 24% (P = 0.032), respectively. The greater training exposure and the long pre-season period in Sweden may explain some of the reported differences.

226 citations


Journal ArticleDOI
TL;DR: Avascularity is considered to be a key factor for the etiology of degenerative tendon disease, and the repair capability after repetitive microtrauma is strongly compromised in avascular tissue of gliding tendons.
Abstract: More than 100 years ago Wilhelm Roux (1895) introduced the term "functional adaptation to anatomy and physiology". Compared with other organ systems the functional adaptation processes are best identifiable in the locomotor system, like for example in the two types of tendons: traction and gliding tendons. Traction tendons are tendons where the direction of pull is in line with the direction of the muscle (e.g. Achilles tendon). Gliding tendons (e.g. tibialis posterior tendon) change direction by turning around a bony or fibrous hypomochlion. In this region the tendon is subjected to intermittent compressive and shear forces and the extracellular matrix consists of avascular fibrocartilage. Avascularity is considered to be a key factor for the etiology of degenerative tendon disease. The repair capability after repetitive microtrauma is strongly compromised in avascular tissue of gliding tendons. Reduced vascularity is not a specific feature of gliding tendons; several studies have shown that the number and size of blood vessels are largely shortened in the waist of the Achilles tendon. However, histological biopsies from degenerated Achilles tendons and Doppler flow examinations revealed a high blood vessel density in patients with degenerative tendon disease. Angiogenesis is mediated by angiogenic factors and recent studies have shown that the vascular endothelial growth factor (VEGF) is highly expressed in degenerative Achilles tendons, whereas VEGF expression is nearly completely downregulated in healthy tendons. Several factors are able to upregulate VEGF expression in tenocytes: hypoxia, inflammatory cytokines and mechanical load. Since VEGF has the potential to stimulate the expression of matrix metalloproteinases and inhibit the expression of tissue inhibitors of matrix metalloproteinases tissue inhibitor of metalloproteinases (TIMP) in various cell types (e.g. endothelial cells, fibroblasts, chondrocytes), this cytokine might play a significant role for the pathogenetic processes during degenerative tendon disease. An animal experiment in the rabbit has shown that local injection of VEGF reduced the material properties of the Achilles tendon. These experimental findings are in accordance with clinical results that a locally administered (in the area with neovascularization) sclerosing drug (Polidocanol) has a beneficial effect on chronic mid-portion Achilles tendinosis. In conclusion, decreased and increased vascularity might be involved in the pathogenesis of degenerative Achilles tendon disease.

209 citations


Journal ArticleDOI
TL;DR: There was a dose–response effect between physical activity and psychosocial well‐being and the most pronounced difference with regard to the level of stress and dissatisfaction was seen between the group with low and the groupWith moderate physical activity, e.g., 2–4 h of walking per week.
Abstract: The associations between physical activity in leisure time with special focus on jogging and the level of mental stress and life dissatisfaction were studied in 12 028 randomly selected men and women aged 20-79 years. The associations were similar in men and women; thus, results are given for pooled data. The odds ratios (ORs) are presented as adjusted for sex, age, body mass index, smoking, alcohol consumption, education and income. With increasing physical activity in leisure time, there was a decrease in high level of stress, between sedentary persons and joggers, OR=0.30 (95% confidence interval (CI) from 0.16 to 0.56). With increasing physical activity there was also a decrease in life dissatisfaction, between sedentary persons and joggers, OR=0.30 (95% CI from 0.18 to 0.52). Although there was a dose-response effect between physical activity and psychosocial well-being the most pronounced difference with regard to the level of stress and dissatisfaction was seen between the group with low and the group with moderate physical activity, e.g., 2-4 h of walking per week. In conclusion, we recommend that increased well-being should be a key argument in future campaigns for increased leisure-time physical activity.

201 citations


Journal ArticleDOI
TL;DR: It is demonstrated that it is possible to use intratendinous microdialysis to investigate human tendons, and normal prostaglandin E2 levels are found in chronic painful tendinosis (Achilles and patellar) tenders, and gene technological analyses of biopsies showed no upregulation of pro‐inflammatory cytokines.
Abstract: The etiology and pathogenesis of chronic tendon pain are unknown. Even though tendon biopsies having shown an absence of inflammatory cell infiltration, anti-inflammatory agents (non-steroidal anti-inflammatory drugs, corticosteroidal injections) are commonly used. We have demonstrated that it is possible to use intratendinous microdialysis to investigate human tendons, and found normal prostaglandin E2 (PGE2) levels in chronic painful tendinosis (Achilles and patellar) tendons. Furthermore, gene technological analyses of biopsies showed no upregulation of pro-inflammatory cytokines. These findings show that there is no PGE2-mediated intratendinous inflammation in the chronic stage of these conditions. The neurotransmitter glutamate (a potent modulator of pain in the central nervous system) was, for the first time, found in human tendons. Microdialysis showed significantly higher glutamate levels in chronic painful tendinosis (Achilles and patellar) tendons, compared with pain-free normal control tendons. The importance of this finding is under evaluation. Treatment is considered to be difficult, and not seldom, surgery is needed. However, recent researches on non-surgical methods have shown promising clinical results. Painful eccentric calf-muscle training has been demonstrated to give good clinical short- and mid-term results on patients with chronic painful mid-portion Achilles tendinosis. Good clinical results were associated with decreased tendon thickness and a structurally more normal tendon with no remaining neovessels. Using ultrasonography (US)+color Doppler (CD), and immunhistochemical analyses of biopsies, we have recently demonstrated a vasculo/neural (Substance-P and Calcitonin Gene-Related Peptide nerves) ingrowth in the chronic painful tendinosis tendon, but not in the pain-free normal tendon. A specially designed treatment, using US- and CD-guided injections of the sclerosing agent Polidocanol, targeting the neovessels outside the tendon, has been shown to cure tendon pain in pilot studies, in a majority of the patients. A recent, randomized, double-blind study verified the importance of injecting the sclerosing substance Polidocanol.

191 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined changes in muscle structure and neuromuscular performance induced by 15 weeks of power training with explosive muscle actions and found that the maximal rate of force development (RFD) of the knee extensor increased from 18,836+/-4282 to 25,443+/-8897 N (P 0.05) in muscle activity (electromyography) of KE.
Abstract: The present study examines changes in muscle structure and neuromuscular performance induced by 15 weeks of power training with explosive muscle actions. Twenty-three subjects, including 10 controls, volunteered for the study. Muscle biopsies were obtained from the gastrocnemius muscle before and after the training period, while maximal voluntary isometric contractions (MVC) and drop jump tests were performed once every fifth week. No statistically significant improvements in MVC of the knee extensor (KE) and plantarflexor muscles were observed during the training period. However, the maximal rate of force development (RFD) of KE increased from 18,836+/-4282 to 25,443+/-8897 N (P 0.05) in muscle activity (electromyography) of KE. The mean percentage for myosin heavy chain and titin isoforms, muscle fiber-type distributions and areas were unchanged. The enhanced performance in jumping as a result of power training can be explained, in part, by some modification in the joint control strategy and/or increased RFD capabilities of the KE.

172 citations


Journal ArticleDOI
TL;DR: The findings of this study suggest that effective prevention and conservative rehabilitation of ankle inversion sprains should include attention to these variables.
Abstract: Ankle sprains are extremely common. However, very little is known about the variables that predispose individuals to these injuries. The purpose of this study was to examine prospectively intrinsic risk factors for inversion sprains in a young physically active female population. One hundred and fifty-nine female physical education students were evaluated for several possible intrinsic risk factors for inversion sprains at the beginning of their academic study. The evaluated intrinsic risk factors included anthropometrical and physical characteristics, ankle joint position sense, isokinetic ankle muscle strength, lower leg alignment characteristics, postural control and muscle reaction time during a sudden inversion perturbation. All sports injuries were registered during 1-3 years and exposure to sport was recorded (mean: 15.33+/-4.33 h a week). Thirty-two (20%) of the 159 females sprained their ankle. The number of ankle sprains per 1000 h of sports exposure was 0.75. The Cox regression analysis revealed that females with less accurate passive joint inversion position sense [hazard ratio (HR): 1.08, 95% confidence interval (CI): 1.02-1.14 for absolute error at 15 degrees inversion], a higher extension range of motion at the first metatarsophalangeal joint (HR: 1.03, 95% CI: 1.00-1.06) and less coordination of postural control (HR: 0.96, 95% CI: 0.93-1.00 for endpoint excursion; HR: 0.94, 95% CI: 0.89-0.99 for maximal endpoint excursion) are at greater risk of an ankle sprain. The findings of this study suggest that effective prevention and conservative rehabilitation of ankle inversion sprains should include attention to these variables.

165 citations


Journal ArticleDOI
TL;DR: This paper considers the literature and some new experimental results important for adaptation of muscle fiber cross‐sectional area and serial sarcomere number, finding that general rules for the regulation of adaptation cannot be derived.
Abstract: This paper considers the literature and some new experimental results important for adaptation of muscle fiber cross-sectional area and serial sarcomere number. Two major points emerge: (1) general rules for the regulation of adaptation (for in vivo immobilization, low gravity conditions, synergist ablation, tenotomy and retinaculum trans-section experiments) cannot be derived. As a consequence, paradoxes are reported in the literature. Some paradoxes are resolved by considering the interaction between different levels of organization (e.g. muscle geometrical effects), but others cannot. (2) An inventory of signal transduction pathways affecting rates of muscle protein synthesis and/or degradation reveals controversy concerning the pathways and their relative contributions. A major explanation for the above is not only the inherently limited control of the experimental conditions in vivo, but also of in situ experiments. Culturing of mature single Xenopus muscle fibers at high and low lengths (allowing longitudinal study of adaptation for periods up to 3 months) did not yield major changes in the fiber cross-sectional area or the serial sarcomere number. This is very different from substantial effects (within days) of immobilization in vivo. It is concluded that overall strain does not uniquely regulate muscle fiber size. Force transmission, via pathways other than the myotendinous junctions, may contribute to the discrepancies reported: because of substantial serial heterogeneity of sarcomere lengths within muscle fibers creating local variations in the mechanical stimuli for adaptation. For the single muscle fiber, mechanical signalling is quite different from the in vivo or in vitro condition. Removal of tensile and shear effects of neighboring tissues (even of antagonistic muscle) modifies or removes mechanical stimuli for adaptation. It is concluded that the study of adaptation of muscle size requires an integrative approach taking into account fundamental mechanisms of adaptation, as well as effects of higher levels of organization. More attention should be paid to adaptation of connective tissues within and surrounding the muscle and their effects on muscular properties.

Journal ArticleDOI
TL;DR: This paper explores how the contractile force generated at the sarcomeres within an individual muscle fiber is transferred through the connective tissue to move the bones.
Abstract: Mechanical force is generated within skeletal muscle cells by contraction of specialized myofibrillar proteins. This paper explores how the contractile force generated at the sarcomeres within an individual muscle fiber is transferred through the connective tissue to move the bones. The initial key point for transfer of the contractile force is the muscle cell membrane (sarcolemma) where force is transferred laterally to the basement membrane (specialized extracellular matrix rich in laminins) to be integrated within the connective tissue (rich in collagens) before transmission to the tendons. Connections between (1) key molecules outside the myofiber in the basement membrane to (2) molecules within the sarcolemma of the myofiber and (3) the internal cytoplasmic structures of the cytoskeleton and sarcomeres are evaluated. Disturbances to many components of this complex interactive system adversely affect skeletal muscle strength and integrity, and can result in severe muscle diseases. The mechanical aspects of these crucial linkages are discussed, with particular reference to defects in laminin-alpha2 and integrin-alpha7. Novel interventions to potentially increase muscle strength and reduce myofiber damage are mentioned, and these are also highly relevant to muscle diseases and aging muscle.

Journal ArticleDOI
TL;DR: In conclusion, training using FAST (3.66 rad/s) lengthening contractions leads to greater hypertrophy and strength gains than SLOW (0.35 rad/s), which may be related to a greater amount of protein remodeling (Z‐band streaming; study II).
Abstract: You might find this additional information useful... This article cites 48 articles, 26 of which you can access free at: http://jap.physiology.org/cgi/content/full/98/5/1768#BIBL This article has been cited by 7 other HighWire hosted articles, the first 5 are: € [Abstract]€ [Full Text]€ [PDF] Am. J. Clinical Nutrition, August 1,€2007; 86€(2): 373-381. and S. M Phillips J. W Hartman, J. E Tang, S. B Wilkinson, M. A Tarnopolsky, R. L Lawrence, A. V Fullertonweightlifters accretion than does consumption of soy or carbohydrate in young, novice, male Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass€ [Abstract]€ [Full Text]€ [PDF] Am J Physiol Regulatory Integrative Comp Physiol, January 1,€2008; 294€(1): R172-R178. J. E. Tang, J. G. Perco, D. R. Moore, S. B. Wilkinson and S. M. Phillips men Resistance training alters the response of fed state mixed muscle protein synthesis in young€ [Abstract]€ [Full Text]€ [PDF] J Appl Physiol, November 1,€2008; 105€(5): 1454-1461. Andersen, P. Aagaard and M. Kjaer L. Holm, S. Reitelseder, T. G. Pedersen, S. Doessing, S. G. Petersen, A. Flyvbjerg, J. L.and light loading intensity Changes in muscle size and MHC composition in response to resistance exercise with heavy€ [Abstract]€ [Full Text]€ [PDF] J Appl Physiol, April 1,€2009; 106€(4): 1412-1418. J. Tannerstedt, W. Apro and E. Blomstrand type II fibers of human skeletal muscle Maximal lengthening contractions induce different signaling responses in the type I and€ [Abstract]€ [Full Text]€ [PDF] J Appl Physiol, February 1,€2010; 108€(2): 306-313. E. Ochi, T. Hirose, K. Hiranuma, S.-K. Min, N. Ishii and K. Nakazato eccentric contractions in rat medial gastrocnemius muscle Elevation of myostatin and FOXOs in prolonged muscular impairment induced byUpdated information and services including high-resolution figures, can be found at: http://jap.physiology.org/cgi/content/full/98/5/1768 Additional material and information about Journal of Applied Physiology can be found at: http://www.the-aps.org/publications/jappl This information is current as of May 31, 2010 . € ISSN: 8750-7587, ESSN: 1522-1601. Visit our website at http://www.the-aps.org/.

Journal ArticleDOI
TL;DR: It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue.
Abstract: Chronic, painful conditions affecting tendons, frequently known as tendinopathy, are very common types of sporting injury. The tendon extracellular matrix is substantially altered in tendinopathy, and these changes are thought to precede and underlie the clinical condition. The tendon cell response to repeated minor injuries or “overuse” is thought to be a major factor in the development of tendinopathy. Changes in matrix turnover may also be effected by the cellular response to physical load, altering the balance of matrix turnover and changing the structure and composition of the tendon. Matrix turnover is relatively high in tendons exposed to high mechanical demands, such as the supraspinatus and Achilles, and this is thought to represent either a repair or tissue maintenance function. Metalloproteinases are a large family of enzymes capable of degrading all of the tendon matrix components, and these are thought to play a major role in the degradation of matrix during development, adaptation and repair. It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue. Further research is required to investigate how these enzyme activities are regulated in tendon and altered in tendinopathy. A profile of all the metalloproteinases expressed and active in healthy and degenerate tendon is required and may lead to the development of new drug therapies for these common and debilitating sports injuries.

Journal ArticleDOI
TL;DR: It is shown that the expression level of tenascin‐C directly correlates with externally applied mechanical stress, as well as with RhoA/RhoA‐dependent kinase‐mediated cytoskeletal tension, which is relevant in medical intervention after ligament and tendon injury.
Abstract: Mechanical forces are essential for connective tissue homeostasis. The extracellular matrix (ECM) plays a key role in the transmission of forces generated by the organism (e.g. muscle contraction) and externally applied (e.g. gravity). The expression of specific ECM proteins such as collagens and tenascin-C, as well as of matrix metalloproteinases, involved in their turnover, is influenced by mechanical stimuli. The precise mechanisms by which mechanical strains are translated into chemical signals and lead to differential gene expression are however not fully understood. Cell-matrix adhesion sites are good candidates for hosting a "mechanosensory switch", as they transmit forces from the ECM to the cytoskeleton and vice versa by physically linking the cytoskeleton to the ECM. Integrins, transmembrane proteins located to these adhesion sites, have been shown to trigger a set of internal signaling cascades after mechanical stimulation. We have shown that the expression level of tenascin-C directly correlates with externally applied mechanical stress, as well as with RhoA/RhoA-dependent kinase-mediated cytoskeletal tension. Presumably other genes are regulated in a similar manner. The changes in ECM composition and mechanical properties derived from mechanical stress are relevant in medical intervention after ligament and tendon injury.

Journal ArticleDOI
TL;DR: Three pain provocation tests used in the diagnosis of chronic groin pain are described and their relationship to defined clinical and MRI criteria has been assessed.
Abstract: The clinical assessment of groin pain in athletes is difficult, with the lack of specific clinical tests being in part responsible. Three pain provocation tests used in the diagnosis of chronic groin pain are described and their relationship to defined clinical and MRI criteria has been assessed. Eighty-nine Australian Rules football players with and without groin symptoms underwent clinical examination followed by history. Three pain provocation tests were performed (named as the Single Adductor, Squeeze and Bilateral Adductor tests). All athletes subsequently underwent MRI of their groin region for the presence of significant pubic bone marrow oedema (BMO). Of the 89, 47 were defined as having chronic groin pain, and 46 had significant BMO with 37 having both chronic groin pain and BMO. The three pain provocation tests demonstrated only moderate sensitivity (range 30-65%). Positive predictive values were moderate to high (67-93%) depending upon the individual test. The Bilateral Adductor test was the most sensitive test with the highest positive predictive values. The high specificity (88-93%) demonstrated should be treated with caution due to the study methodology. Three pain provocation tests of potential value in assessing chronic groin pain in athletes are described. If positive, all three pain provocation tests demonstrated a high likelihood for the athlete having MR-detected parasymphyseal pubic BMO. Further research is required on assessing the clinical usefulness of these tests.

Journal ArticleDOI
TL;DR: Ice massage is ineffective in reducing the indirect markers associated with exercise‐induced muscle damage and enhancing recovery of muscle function in male exercisers unaccustomed to eccentric biased exercise.
Abstract: The purpose of this investigation was to, firstly, examine the effects of repeated applications of ice massage on the indirect markers associated with muscle damage using a within-subjects cross-over design and secondly, to examine how ice massage affects muscle function in both static and dynamic contractions following unaccustomed eccentric exercise. Twelve males performed damaging exercise on two separate occasions. The protocol consisted of three sets of 10 maximal eccentric repetitions of the elbow flexors using isokinetic dynamometry. Subjects were randomly assigned to an ice massage group or placebo group and received treatments immediately post-exercise, 24 and 48 h post-exercise. Muscle function (maximal isometric, slow and fast isokinetic contractions), creatine kinase, myoglobin, muscle soreness, limb girth and range of motion were measured pre, immediately post, 24, 48, 72 and 96 h post-exercise. Significant time effects were observed for all dependent variables (P<0.05). There were no significant differences between treatments. Ice massage is ineffective in reducing the indirect markers associated with exercise-induced muscle damage and enhancing recovery of muscle function in male exercisers unaccustomed to eccentric biased exercise.

Journal ArticleDOI
TL;DR: The Swedish translation of the Children and Youth – Physical Self‐Perception Profile (CY – PSPP) scale was validated and the relation between physical self‐perception and daily physical activity as well as the relationship between physicalSelfPerception and body mass index (BMI) among Swedish school children was examined.
Abstract: Aim: This study validated the Swedish translation of the Children and Youth – Physical Self-Perception Profile (CY – PSPP) scale and examined the relation between physical self-Perception and daily physical activity as well as the relationship between physical self-perception and body mass index (BMI) among Swedish school children. Methods: Forty-eight children aged 11–12 years completed the CY – PSPP twice with 2 weeks in between. Test–retest reliability, concurrent and content validity were calculated. Five hundred and one children, aged 10–14 years, were measured for height and weight and perceived physical self-perception. Activity levels were analyzed using pedometers for 4 consecutive days. Results: Good validity concerning concurrent and content validity was found. Test–retest reliability over a 2-week period was acceptable. In boys a fair and in girls a poor correlation between the sub-domains of the CY – PSPP and physical activity were found and a fair negative correlation between the sub-domains and BMI except for Physical Strength. Conclusion: The CY – PSPP distinguishes between children with low and high physical self-perception. The information is of importance when designing physical activity programs reachable for children with low physical self-esteem. According to the findings it is important to form physical activity programs that support and develop Sport Competence, Physical Condition and sense of Body Attractiveness among children.

Journal ArticleDOI
TL;DR: The purpose of this study was to systematically examine the incidence and severity of quadriceps voluntary activation failure in both lower extremities after acute ACL injury and found that there would be no difference in inhibition by gender.
Abstract: Background: Weakness of the quadriceps femoris muscle after anterior cruciate ligament (ACL) injury and reconstruction has been attributed to incomplete voluntary activation of the muscle. The literature is conflicting on the incidence of incomplete voluntary quadriceps activation after ACL injury because of differences in testing methods and population biases. The purpose of this study was to systematically examine the incidence and severity of quadriceps voluntary activation failure in both lower extremities after acute ACL injury. We hypothesized that the incidence of quadriceps inhibition would be higher in the ACL-injured limbs than the uninvolved limbs, that the incidence of inhibition in the ACL-deficient limbs would be larger than in our historical sample of healthy young individuals tested in the same manner and that there would be no difference in inhibition by gender. Study Design: Prospective, descriptive. Methods: One hundred consecutive patients with acute ACL rupture (39 women and 61 men) were tested when range of motion was restored and effusion resolved, an average of 6 weeks after injury. A burst superimposition technique was used to assess quadriceps muscle activation and strength in all patients. Dependent t-tests were used to compare side-to-side differences in quadriceps strength. Independent t-tests were used to compare incidence of activation failure by gender and make comparisons to historical data on young, active individuals. Results: The average involved side quadriceps activation was 0.92, and ranged from 0.60 to 1.00. The incidence of incomplete activation in the involved side quadriceps was 33 percent and in the uninvolved side quadriceps was 31 percent after acute ACL rupture. The incidence of incomplete activation bilaterally was 21 percent. There was no difference in incidence of quadriceps inhibition by gender. Conclusion: The incidence of voluntary quadriceps inhibition on the involved side was three times that of uninjured, active young subjects, but the magnitude was not large. The incidence of quadriceps inhibition on the uninjured side was similar to the injured side. Clinical relevance: Both the incidence and magnitude of quadriceps inhibition after ACL rupture are lower than have previously been reported. The conventional wisdom, therefore, that quadriceps inhibition is a significant problem in this population is challenged by the results of this study. Differences between this study and others include sufficient practice to ensure a maximal effort contraction and rigorous inclusion criteria. The findings have implications for strength testing as well as rehabilitation. The quadriceps index, an assessment of the injured side quadriceps strength deficit, may be affected by the presence of voluntary activation failure in the uninvolved side.

Journal ArticleDOI
TL;DR: Evidence is provided of the contribution of muscular, tendinous and neural alterations to muscle weakness in old age and the complex interplay between the changes of the contractile tissue with those of the tendinous tissue in relation to the mechanical behavior of the muscle as a whole.
Abstract: The loss of muscle mass associated with ageing only partly explains the observed decline in muscle strength. This paper provides evidence of the contribution of muscular, tendinous and neural alterations to muscle weakness in old age and discusses the complex interplay between the changes of the contractile tissue with those of the tendinous tissue in relation to the mechanical behavior of the muscle as a whole. Despite the considerable structural and functional alterations, the elderly musculoskeletal system displays remarkable adaptability to training in old age and many of these adverse effects may be substantially mitigated, if not reversed, by resistive loading. The interplay between these muscular and tendinous adaptations has an impact both on the length-force and force-velocity relationships of the muscle and is likely to affect the range of motion, rate of force development, maximum force development and speed of movement of the older individual.

Journal ArticleDOI
TL;DR: It is shown that a radiographic abnormality, specifically spondylolysis, is a significant radiological risk factor for low back pain in high school rugby players.
Abstract: The purpose of this study was to examine the relationship between prevalent radiographic abnormalities of the lumbar spine and the incidence of low back pain in high school rugby players. Three hundred and twenty-seven incoming high school rugby players (15-16 years of age) were recruited between 1986 and 1994. All of them underwent athletic physical examination before participation in high school athletics. The relationship between prevalent radiographic abnormalities of the lumbar spine in the pre-participation athletic physical examination and the incidence of low back pain during a 1-year period after the start of participation in athletics was analyzed. Radiographic abnormalities assessed were spondylolysis, disc space narrowing, spinal instability, Schmorl's node, balloon disc, and spina bifida occulta. The frequency of respective radiographic abnormalities was 15.6%, 13.1%, 32.7%, 14.1%, 11.6%, and 30.6%. Two hundred and forty-three players (74.3%) had at least one of these radiographic abnormalities. The incidence of low back pain was 44.0% in players with no such radiographic abnormalities and 41.2% in those with at least one radiographic abnormality. The incidence of low back pain in players with the respective radiographic abnormalities was 72.5%, 46.5%, 46.7%, 39.1%, 34.2%, and 41.0%, and only players with spondylolysis had a significantly higher incidence of low back pain than those with no radiographic abnormalities. This study shows that a radiographic abnormality, specifically spondylolysis, is a significant radiological risk factor for low back pain in high school rugby players.

Journal ArticleDOI
TL;DR: The hypothesis tested here is that training of sufficiently high volume during pregnancy can maintain initial fitness levels and that high‐volume training during pregnancy in initially fit women does not pose a health risk for the mother or the fetus.
Abstract: This study investigates the effects of vigorous exercise during and after pregnancy in top competitive athletes. The hypothesis tested here is that training of sufficiently high volume during pregnancy can maintain initial fitness levels. A second hypothesis, that high-volume training during pregnancy in initially fit women does not pose a health risk for the mother or the fetus, was tested and found to hold in a prior report. The overall aim of the study was to define a safe training regime for the maintenance of fitness in top-level female athletes during pregnancy. Forty-one healthy athletes who had performed exercise regularly prior to conception were followed from gestational week 17 until 12 weeks postpartum while they performed standardized exercise programs. The subjects participated either in a high-volume exercise group (HEG, n=20, 8.4 h week(-1)) or in a medium-volume exercise group (MEG, n=21, 6 h week(-1)). The results show that well-trained women can benefit substantially from training at high volumes during an uncomplicated pregnancy. This can facilitate a rapid return to competitive athletics and physically active life after pregnancy. Guidelines for safe exercise by sufficiently fit women during pregnancy could be modeled on the high-volume exercise regime used here by the HEG.

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TL;DR: The results showed a high intensity and frequency of physical activity in the participating primiparous women, while low‐impact activity seemed to promote continence if urinary leakage was present before pregnancy, it persisted in most women during pregnancy and 1 year post partum.
Abstract: The impact of physical activity on urinary leakage (UL) has previously been considered, but not in relation to first pregnancy and delivery. The aim of this study was to describe physical activity and urinary leakage before, during and after the first childbirth. The subjects who were invited to participate in the study were taken consecutively from nine maternity clinics in the northwest part of Stockholm County, and the study group included 665 primiparous women. The mean age of the women was 28 (range 17-43) years. The women answered one questionnaire during the 36th gestation week and another 1 year post partum. Physical activity/exercises were classified according to their impact on the pelvic floor, and the women were divided into three groups: high-impact exercise (n=327), low-impact exercise (n=84) and the inactive group (n=254). The results showed a high intensity and frequency of physical activity in the participating primiparous women. Risk factors for UL were symptoms of a dysfunctional pelvic floor and connective tissue disorders and high-impact physical activity before pregnancy, while low-impact activity seemed to promote continence. If urinary leakage was present before pregnancy, it persisted in most women during pregnancy and 1 year post partum.

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TL;DR: In conclusion automated metabolic analyser systems are a scientifically robust method for the evaluation of cardiopulmonary function but individual researchers and clinicians must be able to make their own decisions about the level of error that is tolerable for their individual needs.
Abstract: Automated metabolic gas analysis systems have advanced considerably over the past decade. They provide an abundance of information, which is not possible by using the traditional Douglas bag method and have become an essential tool in both physiological monitoring and in the diagnosis of cardiopulmonary disease. The validity and reliability of the different online metabolic analyzer systems are not well known, with relatively few independent studies being published. The purpose of this review was to examine and evaluate current literature regarding the validity and reliability of commercially available metabolic analyzer systems. This review reveals significant differences between the available systems in the way that they capture and process basic respiratory measurements. Online metabolic analyzer systems were found to vary significantly when compared with Douglas bag methods. These variations have the potential to introduce error into the accuracy with which the health of cardiovascular system can be assessed or training loads can be assigned. Compounding this is the fact that many automated systems are a "black box", which makes it easy to generate data without the user having much understanding of how the data were generated. In conclusion automated metabolic analyser systems are a scientifically robust method for the evaluation of cardiopulmonary function. Individual researchers and clinicians must, however, be able to make their own decisions about the level of error that is tolerable for their individual needs. This presents a significant practical challenge in light of the speed with which technical developments in the field occur and we make some suggestions for the formulation of intersystem comparison studies.

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TL;DR: To examine the effects of eccentric and concentric progressive resistance training on muscle torque–angle relationship, 30 young adults were randomly allocated into three groups of 10, control (CTL), eccentric training (ECC) and Concentric training (CON).
Abstract: To examine the effects of eccentric and concentric progressive resistance training on muscle torque-angle relationship, 30 young adults were randomly allocated into three groups of 10, control (CTL), eccentric training (ECC) and concentric training (CON). The ECC and CON groups performed seven sessions over 3 weeks of progressive resistance training of the right hamstrings muscle, using a standard barbell and a leg curl machine. Torque-angle relationship was measured before and 4, 11 and 18 days after the end of training. Voluntary isometric torque was recorded at seven test angles, with the subject prone (20-80 degrees; 0 degrees is full extension). In the CON group, the angle of peak isometric torque increased from 46.0 +/- 5.2 degrees pre-training to 53.0 +/- 14.9 degrees on day 4 following training (P<0.05). In the ECC group, peak torque was increased over baseline on days 4 and 11 post-training, particularly at extended knee angles (P<0.05). The angle at which peak torque occurred was decreased on day 4 (50.0 +/- 8.2 degrees pre-training, 29.0 +/- 7.4 degrees on day 4) and on day 11 (both P<0.01), but was similar to baseline 18 days after training. ECC therefore induced a temporary change in torque-angle relationship.

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TL;DR: The purpose of this study was to compare the maximal oxygen uptake (VO2max) in 18–19‐year‐old Norwegian men from 1980 to 1985 and 2002 and to investigate the relationship between VO2max and education and smoking habits in the sample from 2002.
Abstract: The purpose of this study was to compare the maximal oxygen uptake (VO2max) in 18-19-year-old Norwegian men from 1980 to 1985 and 2002. In addition, we investigated the relationship between VO2max and education and smoking habits in the sample from 2002. From 1980 to 1985, VO2max was predicted using the Astrand-Rhyming bicycle test for 183 610 eighteen-year-old Norwegian men (91% of the male Norwegian population in this age group). In 2002, the same test was performed on a representative sample of the same age population (N=1028). VO2max (mL x kg(-1)x min(-1)), decreased by 8%, body weight increased by 7% and body mass index (BMI) increased by 6% over the approximately 20-year period (P<0.01). Results from the 2002 sample revealed that smokers had a lower VO2max than non-smokers and vocational students had a lower VO2max than academic students (P<0.05). The average reduction in VO2max was because of an increased number of men with low or very low VO2max, and a reduced number of men with high VO2max values. This is of particular concern since the prevalence of lifestyle-related diseases is higher in groups with low VO2max.

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TL;DR: There was a high similarity of sonographic spectrum of abnormal findings among the groups and longitudinal follow‐ups are required to determine the clinical importance of the sonographic spectrums and the occurrences of abnormal finding in asymptomatic athletes' shoulders.
Abstract: This study compared the thickness of the biceps and supraspinatus tendons, the widths of the subacromial space in the frontal and scapular planes, and abnormal sonographic findings in the shoulders of injured, and uninjured elite college baseball athletes and healthy controls. This study recruited two groups of 42 and 12 athletes, with and without histories of shoulder injuries, respectively, as well as one control group of 16 college students who were matched for physical characteristics but not involved in sports. The results showed that the thickness of the biceps and supraspinatus tendons and the subacromial space widths at 0 degrees and 90 degrees shoulder abduction in the frontal plane were significantly greater in the athletes than in the controls (P-values <0.004). The occurrences of the acromioclavicular joint bulging, bicep tendon degeneration, infraspinatus tendon degeneration and infraspinatus cortical irregularity differ significantly between the injured athlete and the group of uninjured athletes and controls (P-values <0.05). However, only infraspinatus tendon degeneration corresponded to the injury histories. There was a high similarity of sonographic spectrum of abnormal findings among the groups. Longitudinal follow-ups are required to determine the clinical importance of the sonographic spectrums and the occurrences of abnormal finding in asymptomatic athletes' shoulders.

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TL;DR: Evidence is provided that the most beneficial time for physical exercise to exhibit its effect on bone development is in the earlier pubertal period for normal school children, but the positive effect on the lumbar spine is also demonstrated in Tanner Stage II.
Abstract: This study aimed to evaluate the influence of leisure-time physical activity on the development of bone mass and density in early pubertal girls. Scores of physical activity were obtained from 242 Finnish girls (10-12 years old within Tanner Stages I-II) using a questionnaire. Bone mass and density were assessed using different densitometric techniques. At Tanner Stage I, active girls had significantly higher bone mineral mass (BMC) and areal bone mineral density (aBMD) of the whole body and cortical volumetric BMD and thickness of the tibial shaft compared with sedentary girls (P<0.05). On the other hand, the active girls at Tanner Stage II showed significantly higher values only in BMC and aBMD at the lumbar spine (P=0.017 and P=0.007, respectively). These indicated that girls at Tanner Stage I with higher leisure-time physical activity level benefited more from physical activity in terms of their bone development than their less active counterparts. Our results provide evidence that the most beneficial time for physical exercise to exhibit its effect on bone development is in the earlier pubertal period for normal school children, but the positive effect on the lumbar spine is also demonstrated in Tanner Stage II.

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TL;DR: It is found that hamstring injury occurrence in elite soccer players after preseason strength training with eccentric methods is more common than previously thought.
Abstract: Scand J Med Sci Sports 2003 Aug: 13(4): 244–50 Hamstring injury occurrence in elite soccer players after preseason strength training with eccentric

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TL;DR: Stretching appears to decrease muscle force output in a single joint isomet contraction and rate of force development in a multiple joint isometric contraction.
Abstract: Eight moderately active male subjects where tested for peak force in an isometric knee extension test and peak force and rate of force development in an isometric squat test. Both tests where performed at a 100 degrees knee angle and average integrated electromyography (IEMG) was measured from the vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) muscles. Subjects performed the two conditions, stretching (S) or control (C) in a randomized order. Subjects where tested for baseline strength measures in both the isometric knee extension and isometric squat and then either stretched or sat quietly for 10 min. Following S or C subjects where then tested at six time points. Following S peak force in the isometric knee extension was significantly (P < or = 0.05) less than C at 1, 2, 8 and 16 min post. No significant difference in peak force was found between S and C in the isometric squat. However, following S the rate of force development in the isometric squat was significantly less than C at immediately post. No significant differences where observed in IEMG of the VM or VL between S and C in either the isometric knee extension or isometric squat. However, IEMG significantly decreased in the BF at 1 min post after S in comparison with C in both the isometric knee extension and isometric squat. Stretching appears to decrease muscle force output in a single joint isometric contraction and rate of force development in a multiple joint isometric contraction. Possible changes in agonist-antagonist muscle activity patterns need to be further examined.