举重运动员等动肌力特征的分析与研究   总被引：1，自引：0，他引：1  

张前锋 《广州体育学院学报》2012,32(1):86-89

本研究利用CYBEX-6000型测力系统,对国家举重队和广东省举重队部分运动员的等动肌力特征进行分析和研究,综合归纳出举重运动员等动肌力的总体规律特征,提出针对性的建议.  相似文献   

生酮饮食对体重管理、肌肉合成以及运动表现的影响          下载免费PDF全文

康杰 《体育科研》2018,(1):1-16

自20世纪20年代以来,极低碳水化合物饮食或生酮饮食疗法被应用于癫痫的治疗,甚至在某些情况下能够完全取代药物治疗。1970年以后,这种饮食疗法作为一种肥胖治疗手段而被广泛知晓 。生酮饮食（Ketogenic Diets,KD）是指碳水化合物减少（通常小于20 g/d或低于每天摄入总能量的5%）而蛋白质和脂肪含量相对增加的饮食。目前认为这三大营养物质的重排可以诱导生理性酮症,进而减轻体重。近年来,许多运动员也希望通过生酮饮食减脂以取得更好的运动表现。尽管生酮饮食在体重管理方面作用显著,但它是否能够维持或提高体能表现仍不明确。文章讨论了生酮饮食的代谢效应和潜在风险,以及近期关于生酮饮食对体重减轻、肌肉合成和运动表现影响的研究进展。  相似文献   

Short- and long-term reliability of leg extensor power measurement in middle-aged and older adults     

Christopher Hurst  Alan M Batterham  Kathryn L Weston  Matthew Weston 《Journal of sports sciences》2018,36(9):970-977

Muscular power is important for maintaining physical functioning with aging. Proper quantification of the reliability of muscular power tests is crucial to inform monitoring of individuals and sample size planning for interventional studies. This study evaluated short- and long-term reliability of leg extensor power measurement in 72 adults (age 62.7 ± 8.6 years). Participants completed four repeat trials on the Nottingham leg extensor power rig, with a further trial twelve weeks later. Mean change, typical error, and intraclass correlation coefficients (ICC) were calculated. For short-term reliability, mean change in power output was trivial after two trials (1.2–4.8%). Typical errors were small following four trials in the dominant leg of males (10.9–5.8%), three in the non-dominant leg of males (9.9–6.2%) and the dominant leg of females (10.0–9.6%) and two in the non-dominant leg in females (8.3%). Intraclass correlation coefficients (ICCs) were very high (0.88–0.96). For long-term reliability, mean change remained trivial (1.0–2.5%), typical errors remained small (5.8–8.6%), and ICCs very high (0.94–0.96). The leg extensor power rig is a reliable method for assessing lower body muscular power, both short- and long-term, with only minimal habituation effects.  相似文献   

Specific muscle synergies in national elite female ice hockey players in response to unexpected external perturbation     

Minhee Kim  Yushin Kim  Hyeyoung Kim 《Journal of sports sciences》2018,36(3):319-325

This study aimed to investigate specific muscle synergies in elite ice hockey players indicating highly developed postural control strategies used to restore balance against unexpected external perturbations. Seven elite athletes (EA) on the women’s national ice hockey team and 7 non-athletes (NA) participated in this study. Based on trajectories of centre of mass (COM), analysis periods were divided into an initial phase (a balance disturbance after perturbation onset) and a reversal phase (a balance recovery response), respectively. Muscle synergies were extracted at each phase by using non-negative matrix factorization. k-means cluster analysis was performed to arrange similar muscle synergies in all participants. EA showed significantly shorter recovery period of COM and smaller body sway than NA. In the initial phase, we identified 2 EA-specific synergies related to ankle plantar flexors or neck extensors. In the case of an NA-specific synergy, co-activation of the ankle plantar flexors and dorsiflexors was found. In the reversal phase, no specific muscle synergies were identified. As the results, EA-specific muscle synergies showed low co-activation strategy of agonists and antagonists in ankle and neck extensors. Our results could provide critical information for rehabilitation strategies in athletes requiring high postural stability.  相似文献   

Skeletal surveys in young,injured children: A systematic review     

《Child abuse & neglect》2018

Skeletal surveys (SSs) have been identified as a key component of the evaluation for suspected abuse in young children, but variability in SS utilization has been reported. Thus, we aimed to describe the utilization patterns, yield, and risks of obtaining SS in young children through a systematic literature review. We searched PubMed/MEDLINE and CINAHL databases for articles published between 1990 and 2016 on SS. We calculated study-specific percentages of SS utilization and detection of occult fractures and examined the likelihoods that patient characteristics predict SS utilization and detection of occult fractures. Data from 32 articles represents 64,983 children <60 months old. SS utilization was high (85%-100%) in studies of infants evaluated by a child protection team for suspected abuse and/or diagnosed with abuse except in one study of primarily non-pediatric hospitals. Greater variability in SS utilization was observed across studies that included all infants with specific injuries, such as femur fractures (0%–77%), significant head injury (51%–82%), and skull fractures (41%–86%). Minority children and children without private insurance were evaluated with SS more often than white children and children with private insurance despite lack of evidence to support this practice. Among children undergoing SS, occult fractures were frequently detected among infants with significant head injury (23%–34%) and long bone fractures (30%) but were less common in infants with skull fractures (1%–6%). These findings underscore the need for interventions to decrease disparities in SS utilization and standardize SS utilization in infants at high risk of having occult fractures.  相似文献   

Acupuncture on Intracellular Ionic Distribution inMuscle Injury and Its Mechanism     

QU Zhuqing  LU Dinghou  WANG Yirun 《北京体育大学学报》1995,(Z2)

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A new linearly-combined bi-exponential model for kinetic analysis of the isometric relaxation process of <Emphasis Type="Italic">Bufo gastrocnemius</Emphasis> under electric stimulation in vitro     

Guo R  Li SB  Zhao LN  Zhao YS  Lu W  Yuan P  Deng P  Liao F 《Journal of Zhejiang University. Science. B》2007,8(12):867-874

There was a slow-relaxing tail of skeletal muscles in vitro upon the inhibition of Ca^2＋-pump by cyclopiazonic acid （CPA）. Herein, a new linearly-combined bi-exponential model to resolve this slow-relaxing tail from the fast-relaxing phase was investigated for kinetic analysis of the isometric relaxation process of Bufo gastrocnemius in vitro, in comparison to the single exponential model and the classical bi-exponential model. During repetitive stimulations at a 2-s interval by square pulses of a 2-ms duration at 12 V direct currency （DC）, the isometric tension of Bufo gastrocnemius was recorded at 100 Hz. The relaxation curve with tensions falling from 90% of the peak to the 15th datum before next stimulation was analyzed by three exponential models using a program in MATLAB 6.5. Both the goodness of fit and the distribution of the residuals for the best fitting supported the comparable validity of this new bi-exponential model for kinetic analysis of the relaxation process of the control muscles. After CPA treatment, however, this new bi-exponential model showed an obvious statistical superiority for kinetic analysis of the muscle relaxation process, and it gave the estimated rest tension consistent to that by experimentation, whereas both the classical bi-exponential model and the single exponential model gave biased rest tensions. Moreover, after the treatment of muscles by CPA, both the single exponential model and the classical bi-exponential model yielded lowered relaxation rates, nevertheless, this new bi-exponential model had relaxation rates of negligible changes except much higher rest tensions. These results suggest that this novel linearly-combined bi-exponential model is desirable for kinetic analysis of the relaxation process of muscles with altered Ca2^＋-pumping activity.  相似文献   

Strategies to maintain skeletal muscle mass in the injured athlete: Nutritional considerations and exercise mimetics     

Benjamin T. Wall  James P. Morton 《European Journal of Sport Science》2015,15(1):53-62

Abstract

The recovery from many injuries sustained in athletic training or competition often requires an extensive period of limb immobilisation (muscle disuse). Such periods induce skeletal muscle loss and consequent declines in metabolic health and functional capacity, particularly during the early stages (1–2 weeks) of muscle disuse. The extent of muscle loss during injury strongly influences the level and duration of rehabilitation required. Currently, however, efforts to intervene and attenuate muscle loss during the initial two weeks of injury are minimal. Mechanistically, muscle disuse atrophy is primarily attributed to a decline in basal muscle protein synthesis rate and the development of anabolic resistance to food intake. Dietary protein consumption is of critical importance for stimulating muscle protein synthesis rates throughout the day. Given that the injured athlete greatly reduces physical activity levels, maintaining muscle mass whilst simultaneously avoiding gains in fat mass can become challenging. Nevertheless, evidence suggests that maintaining or increasing daily protein intake by focusing upon the amount, type and timing of dietary protein ingestion throughout the day can restrict the loss of muscle mass and strength during recovery from injury. Moreover, neuromuscular electrical stimulation may be applied to evoke involuntary muscle contractions and support muscle mass maintenance in the injured athlete. Although more applied work is required to translate laboratory findings directly to the injured athlete, current recommendations for practitioners aiming to limit the loss of muscle mass and/or strength following injury in their athletes are outlined herein.  相似文献   

Modeling of musculoskeletal structure and function using a modular bond graph approach     

Laura A. Wojcik 《Journal of The Franklin Institute》2003,340(1):63-76

The dynamic effects of muscle strength, timing of muscle activations, and body geometry have been modeled for a wide variety of human activities. These types of models require the development of complex system equations that account for the effects of rigid-body dynamics, musculotendon actuators, passive and active resistance to motion, and other physiological structures. One way in which model refinement can be expedited is through the use of bond graph modeling techniques. While bond graph techniques have been used extensively in a broad variety of applications, they have been used only sparingly in the field of biomechanics, despite the potential suitability of a modular, multidomain approach to the modeling of musculoskeletal function. In the current paper, bond graph modules representing muscle function and rigid-body motions of underlying bone structures are introduced. The system equations generated with the use of these models are equivalent to those developed with more traditional techniques, but the modules can be more easily used in conjunction with control models of neuromuscular function for the simulation of overall dynamic motor performance.  相似文献   

Angle-specific knee muscle torques of ACL-reconstructed subjects and determinants of functional tests after reconstruction     

Özge Çınar-Medeni  Gulcan Harput  Gul Baltaci 《Journal of sports sciences》2019,37(6):671-676

The purposes of this study were to analyse (a) if “angle-specific” (AS) flexor and extensor torques were different between ACL-reconstructed and uninvolved limbs, (b) the difference in peak torque occurrence angles for concentric and eccentric knee flexor and extensor torques between involved and uninvolved limbs and (c) if AS concentric and eccentric knee flexor and extensor torques are determinants of performance in the “single-leg hop test” (SLHT) and “vertical jump and reach test” (VJRT) in ACL-reconstructed legs. Twenty-seven male ACL-reconstructed volunteers were included in the study. Isokinetic knee muscle strength, SLHT and VJRT were performed 6 months after ACL reconstruction. No difference was found in extremity and knee joint angle interaction for concentric and eccentric flexor and extensor torques (p > 0.05). Peak torque occurrence angles were not different between involved and uninvolved limbs (p > 0.05). In involved extremities, concentric knee extensor strength at 90° was a determinant of SLHT performance (R² = 0.403, p < 0.05), and concentric knee extensor strength at 60° was a determinant of VJRT (R² = 0.224, p < 0.05). Assessment of AS concentric knee extensor strength at 60° and 90° might be important, because these were determinants of functional test performance.  相似文献