Medicine and sport science最新文献

L-Carnitine is a conditionally essential nutrient and plays an important role in mitochondrial β-oxidation. As a dietary supplement for athletes, L-carnitine has been investigated for its potential to enhance β-oxidation during exercise ultimately to improve performance. While some studies have shown a positive impact on VO(2 max) and other performance measures, other studies have found contradictory results. As such, investigations to a different mechanism by which L-carnitine supplementation could impact exercise and recovery were explored. Based on findings from cardiovascular research that L-carnitine enhances vascular endothelial function, an alternate hypothesis was developed. The hypothesis is centered on improving blood flow to muscle tissues and decreasing hypoxic stress and its resulting sequelae. Studies have shown a decrease in markers of purine catabolism and free radical generation and muscle soreness as a result of L-carnitine supplementation. Direct assessment of muscle tissue damage via magnetic resonance imaging also indicates the ability of L-carnitine to attenuate tissue damage related to hypoxic stress. L-Carnitine is regarded as a safe supplement for athletes and has been shown to positively impact the recovery process after exercise.

Recent attention has focused on the biological pathways by which tendons heal leading to the identification of some growth factors (GFs) with involvement in this process. No studies have been published on the time course of the various GFs during the tendon healing process in vivo in humans. We review what is known about these GFs and their role in tendon healing.

Regular consumption of fruits and vegetables (FV) is widely regarded as an important contributor to a healthy diet. Inadequate consumption of plant foods is associated with an inadequate supply of important micronutrients like vitamins, phytochemicals and minerals. In athletes a deficit of these micronutrients can lead to excessive production of reactive oxygen and nitrogen species that induce tissue damage, a higher frequency of inflammatory processes, decreased immunity, increased susceptibility to injury, and prolonged recovery. But many athletes rarely achieve the recommended intake of FV due to difficult coordination of training activities and food intake, or due to problems with digestion of FV. Therefore, in recent years more and more sports people have adopted supplemental FV concentrates to work around timing problems with uptake and the detrimental digestive effects during training of high FV intake. It is thought that supplementation of an athlete's basic diet with mixed FV concentrates can promote stable health and immunity, in order to provide a basis for optimal adaptation and performance. The intention of this article is to build a bridge between the science behind FV supplementation in exercise on the one hand and the practical relevance of its application on the other. For that purpose this paper addresses three questions: Is supplementation with a mixed FV concentrate to the athlete's diet appropriate to ensure stable health and immunity? Can supplementation with a mixed FV concentrate improve performance? Counseling guidance: how can sport nutrition advisors decide whether or not to supplement with mixed FV concentrates?

Strenuous physical activity increases the risk of musculoskeletal injury and can induce muscle damage resulting in acute inflammation and decreased performance. The human body's natural response to injury results in inflammation-induced pain, swelling, and erythema. Among sports medicine physicians and athletic trainers, the mainstays of urgent treatment of soft tissue injury are rest, ice, compression, and elevation (RICE). In order to reduce pain and inflammation, anti-inflammatory agents such as non-steroidal anti-inflammatory drugs (NSAIDs) act on the multiple inflammatory pathways, which, although often very effective, can have undesirable side effects such as gastric ulceration and, infrequently, myocardial infarction and stroke. For centuries, natural anti-inflammatory compounds have been used to mediate the inflammatory process and often with fewer side effects. Tart cherries appear to possess similar effectiveness in treating the inflammatory reaction seen in both acute and chronic pain syndromes encountered among athletes and non-athletes with chronic inflammatory disease. This article reviews the antioxidant and anti-inflammatory effects of tart cherries on prevention, treatment, and recovery of soft tissue injury and pain.

Glycolysis involves the oxidation of two neutral hydroxyl groups on each glycosyl (or glucosyl) unit metabolised, yielding two carboxylic acid groups. During low-intensity exercise these, along with the remainder of the carbon skeleton, are further oxidised to CO(2) and water. But during high-intensity exercise a major portion (and where blood flow is impaired, then most) is accumulated as lactate anions and H(+). The accumulation of H(+) has deleterious effects on muscle function, ultimately impairing force production and contributing to fatigue. Regulation of intracellular pH is achieved over time by export of H(+) out of the muscle, although physicochemical buffers in the muscle provide the first line of defence against H(+) accumulation. In order to be effective during high-intensity exercise, buffers need to be present in high concentrations in muscle and have pK(a)s within the intracellular exercise pH transit range. Carnosine (β-alanyl-L-histidine) is ideal for this role given that it occurs in millimolar concentrations within the skeletal muscle and has a pK(a) of 6.83. Carnosine is a cytoplasmic dipeptide formed by bonding histidine and β-alanine in a reaction catalysed by carnosine synthase, although it is the availability of β-alanine, obtained in small amounts from hepatic synthesis and potentially in greater amounts from the diet that is limiting to synthesis. Increasing muscle carnosine through increased dietary intake of β-alanine will increase the intracellular buffering capacity, which in turn might be expected to increase high-intensity exercise capacity and performance where this is pH limited. In this study we review the role of muscle carnosine as an H(+) buffer, the regulation of muscle carnosine by β-alanine, and the available evidence relating to the effects of β-alanine supplementation on muscle carnosine synthesis and the subsequent effects of this on high-intensity exercise capacity and performance.

Glycerol ingestion creates an osmotic drive that enhances fluid retention. The major practical applications for athletes are to either (i) hyperhydrate before exercise so that they have more fluid to be lost as sweat during subsequent performance, thereby delaying the progression of dehydration from becoming physiologically significant, or (ii) improve both the rate of rehydration and total fluid retention following exercise. Recently we showed that rehydration may be improved further by combining glycerol with intravenous fluids. Improvements in endurance time, time trial performance and total power and work output have been seen during exercise following glycerol-induced hyperhydration or rehydration. Another recent trial showed that the increased body weight associated with the extra fluid does not inadvertently affect running economy. Concerns that the haemodilution associated with the fluid retention in the vascular space may be sufficient to mask illegal doping practices by athletes led the World Anti-Doping Agency (WADA) to add glycerol to its list of prohibited substances in 2010. Recent evidence suggests that doses of > 0.032 ± 0.010 g/kg lean body mass (much lower than those required for rehydration) will result in urinary excretion that may be detectable, so athletes under the WADA jurisdiction should be cautious to limit their inadvertent glycerol intake.

The arthroscopic approach for rotator cuff repair is extensively used worldwide. Different repairing procedures have evolved with the aim of restoring anatomy and function of rotator cuff tendon. Several studies have analyzed biomechanical factors to understand their influence on tendon to bone healing and improve repair configurations. From a biomechanical point of view, single-row anchor techniques are not able to restore all of the original footprint of the rotator cuff, and result in circumferential tension around the tendon. Transosseus simple suture repairs may have greater potential for healing at the tendon-bone interface, because they allow a larger insertion site area and better pressure characteristics. Biomechanically, double-row suture anchor repair increases the area of contact and the initial fixation strength, decreases the load for each suture loop, knot and anchor, and decreases the stress at each suture-cuff contact point. To optimize healing, transosseous-equivalent techniques have been developed. The oblique suture bridges allow greater pressurized contact, low profile, and interconnection between fixation points that permits to shear load. Clinical studies showed equivalent clinical results of single- and double-row suture anchor repair. However, to date, there are no randomized controlled trials on transosseous or transosseous-equivalent techniques for rotator cuff repair. Clearly, studies of higher levels of evidence, including large randomized trials, should be conducted. Future trials should use validated functional and clinical outcomes, adequate methodology, and be sufficiently powered.

Degenerative, retracted, massive rotator cuff tears present surgeons with distinct challenges. Patient selection is key to a successful outcome. Treatment strategies range from non-operative to progressively more complex surgical options, including debridement, partial repair, complete repair utilizing margin convergence and interval slides, tendon transfers, arthrodesis, and arthroplasty. The rationale behind each of these options and more are discussed along with guidance for selecting the appropriate treatment strategy for individual patients. Outcomes of various treatment approaches are discussed as well to facilitate surgeons to successfully manage patients with retracted and degenerative tears of the rotator cuff.

Repair of rotator cuff tears is a common procedure. Prior to approaching this surgery, it should be realized that each surgical step can lead to complications, including those related to positioning and anaesthesia. Stiffness, infection and failure of repair are the more frequent complications reported.

The objective of this article is to provide an overview of the current knowledge related to the epidemiology of injury in selected adventure and extreme sports. PubMed and Google Scholar were searched using the terms 'epidemiology', 'injury,' 'adventure sports' and 'extreme sports'. Publications from the past 10 years were largely selected, but commonly referenced or highly regarded older publications were also included. References lists of articles identified in the search strategy were also searched and articles selected that were judged to be relevant. Important aspects of the epidemiology of injury related to adventure and extreme sports are discussed including occurrence of injury, who is affected by injury, where and when injury occurs, injury outcome, risk factors, inciting events, prevention and further research. Given the life-changing impact injury can have in sports (personal, social, financial, psychological, political, and medical), the current paucity of well-designed descriptive and particularly analytical epidemiological studies in some adventure and extreme sports is disturbing. The importance of denominator-based and longitudinal data collection in obtaining an accurate picture of injury risk and severity and as a basis for testing risk factors and evaluating preventive measures is emphasized.