In vivo behavior of vastus lateralis muscle during dynamic performances

Length changes in vastus lateralis fascicles were measured in vivo using ultrasonography during one-legged squat jumps (SJ), counter movement jumps (CMJ), and drop jumps (DJ) in the sledge apparatus (n = 9). Patellar tendon forces were recorded simultaneously with an optic fiber technique from 4 subjects. Fascicle length changes were compared with muscletendon unit length changes calculated from kinematic recordings. In general, the tendomuscular and fascicle length changes demonstrated similar patterns. During SJ the fascicles showed shortening throughout the action while during CMJ and DJ they underwent stretch-shortening cycle. In DJ greater muscular activity in braking phase.     

Connective tissue adaptations in the fingers of performance sport climbers

Abstract

This study investigates the changes of the connective tissue in the fingers of performance sport climbers resulting after a minimum of 15 years of climbing. Evaluation was performed by ultrasonography on the palmar side of the fingers (Dig) II–V to measure the thickness of the A2 and A4 annular pulleys, the flexor digitorum superficialis (FDS) and profundus (FDP) tendons and the palmar plates (PP's) of the proximal interphalangeal (PIP) as well as distal interphalangeal (DIP) joint in sagittal and axial direction. Totally, 31 experienced male sport climbers (mean age 37y, 30–48y grade French scale median 8b, range 7b+ to 9a+) participated in the study. The control-group consisted of 20 male non-climbers (age 37y, 30–51y). The A2 and A4 pulleys in climbers were all significantly thicker (A2 Dig III 62%, Dig IV 69%; A4 Dig III 69%, Dig IV 76%) as compared to non-climbers pulleys. All PP's of the DIP joints were also significantly thicker, particularly at Dig III and IV (76 and 67%), whereas the PP's at PIP joints were only scarce significant for three joints. Differences of the diameter of the flexor tendons were less distinct (1–21%) being significant only over the middle phalanx. High load to the fingers of rock climbers after a minimum of 15 years of climbing years induced considerable connective tissue adaptions in the fingers, most distinct at the flexor tendon pulleys and joint capsule (PP) of the DIP joints and well detectable by ultrasound.     

The influence of stretching and warm‐up exercises on Achilles tendon reflex activity

The aim of this study was to investigate the acute effects of prior exercise (warm‐up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min) and (3) after a 10‐min warm‐up run on a treadmill. Tendon tap reflex force was elicited in the triceps surae of the right leg by means of a standardized reflex hammer and measured in a custom‐built fixture. Electromyographic (EMG) signals were recorded with surface electrodes over the medial head of the gastrocnemius (G) and the soleus (S). Low coefficients of variation within subjects contrasted with high between‐subject variations, indicating highly individual reflex characteristics. After stretching, reductions in the peak force (‐5%; P < 0.05), the force rise rate (‐8%; P < 0.01), the half relaxation rate (‐5%; N.S.), the EMG amplitudes (G, ‐16%; S, ‐17%; P < 0.01) and integrals (G, ‐15%; S, ‐18%; P < 0.01), and an increase in EMG latencies (G, +3%; S, +1%; P < 0.01), were found compared with the values obtained without prior exercise. After running, the peak force reached the values obtained without prior exercise (‐2%; N.S.), the force rise rate and half relaxation rate increased by 8 and 12%, respectively (P < 0.01), and the impulse (force‐time integral; ‐12%), EMG amplitudes (G, ‐20%; S, ‐23%; P < 0.01), integrals (G, ‐18%; S, ‐23%; P < 0.01) and latencies (G, ‐1%; S, ‐2%; P < 0.01) decreased significantly. The changes in the force characteristics observed after the stretching treatment indicate improved muscle compliance that might reduce the risk of injury. On the other hand, the changes after the additional warm‐up run had a more pronounced influence with regard to improved force development and a decreased EMG activity, which can be viewed as a performance‐enhancing effect.     

ACL reconstruction with BPTB autograft and irradiated fresh frozen allograft

Objective: To analyze the clinical outcomes of arthroscopic anterior cruciate ligament (ACL) reconstruction with irradiated bone-patellar tendon-bone (BPTB) allograft compared with non-irradiated allograft and autograft. Methods: All BPTB allografts were obtained from a single tissue bank and the irradiated allografts were sterilized with 2.5 mrad of irradiation prior to distribution. A total of 68 patients undergoing arthroscopic ACL reconstruction were prospectively randomized consecutively into one of the two groups (autograft and irradiated allograft groups). The same surgical technique was used in all operations done by the same senior surgeon. Before surgery and at the average of 31 months of follow-up (ranging from 24 to 47 months), patients were evaluated by the same observer according to objective and subjective clinical evaluations. Results: Of these patients, 65 (autograft 33, irradiated allograft 32) were available for full evaluation. When the irradiated allograft group was compared to the autografi group at the 31-month follow-up by the Lachman test, the anterior drawer test (ADT), the pivot shift test, and KT-2000 arthrometer test, statistically significant differences were found. Most importantly, 87.8% of patients in the autograft group and just only 31.3% in the irradiated allograft group had a side-to-side difference of less than 3 mm according to KT-2000. The failure rate of the ACL reconstruction with irradiated allograft (34.4%) was higher than that with autograft (6.1%). The anterior and rotational stabilities decreased significantly in the irradiated allograft group. According to the overall International Knee Docu-mentation Committee (IKDC), functional and subjective evaluations, and activity level testing, no statistically significant dif-ferences were found between the two groups. Besides, patients in the irradiated allograft group had a shorter operation time and a longer duration of postoperative fever. When the patients had a fever, the laboratory examinations of all patients were almost normal. Blood routine was normal, the values of erythrocyte sedimentation rate (ESR) were 5-16 mm/h and the contents of C reactive protein (CRP) were 3-10 mg/L. Conclusion: We conclude that the short term clinical outcomes of the ACL reconstruction with irradiated BPTB allograft were adversely affected. The less than satisfactory results led the senior authors to discontinue the use of irradiated BPTB allograft in ACL surgery and not to advocate using the gamma irradiation as a secondary sterilizing method.     

末端病大鼠跟腱修复中胶原表达的研究

以雄性Wistar大鼠为实验材料,采用电刺激跳跃法建立末端病大鼠跟腱损伤模型．通过动态观察造模后末端病大鼠跟腱修复过程中胶原Ⅰ和胶原Ⅲ基因表达和蛋白含量的变化,探讨胶原在末端病大鼠跟腱修复中的作用及其机制。结果显示：（1）在末端病大鼠跟腱修复过程中胶原Ⅰ在转录水平上的表达和蛋白含量的变化表现出先下降后升高的规律,表明胶原Ⅰ在跟腱早期修复过程中被抑制,（2）胶原Ⅲ在转录水平上的表达和蛋白含量均出现先升高后降低的变化特点,提示胶原Ⅲ在跟腱修复的早期阶段起着十分重要的作用,这种作用在修复的前7d效果非常明显：（3）末端病大鼠跟腱修复初期胶原Ⅰ合成被抑制和胶原Ⅲ含量的增加,表明胶原Ⅲ能代偿被抑制合成的胶原Ⅰ,积极参与肌腱的再生,直至胶原Ⅰ代谢被激活后,两者共同促进肌腱的修复.     

肌腱疲劳性损伤与胶原合成

腱病主要是因为过度使用所导致的疲劳性损伤,明确重复负载下肌腱中分子反应不仅有利于理解腱病发展,而且有利于发现新的预防、治疗和康复措施。本文综述了运动后和疲劳负载下,肌腱中胶原的合成和生长因子的作用,以探讨肌腱疲劳性损伤早期的分子机制、资料研究表明,不同运动和疲劳负载下肌睫中胶原亚型表达不同,并具有载荷剂量依赖性;在这些机械刺激下一些生长因子如生长因子（TGFβ-1）、胰岛素生长因子（IGF-Ⅰ）、白介素-6（IL-6）等可能起到重要的调节作用。     

男性青少年血清IGF-1浓度与下肢骨骼、肌肉形态、机能发育的关系

探讨男性青少年生长发育过程中血清IGF-1水平与下肢骨骼和肌肉形态、机能发育的关系以及运动训练对青少年生长发育及血IGF-1分泌规律的影响。对68名青春发育期男性青少年的身高、体重、下肢长、小腿长以及小腿三头肌肌腹和肌腱长度等身体形态学指标及反映下肢跳跃能力的指标进行测试、同步检测了血清IGF-1浓度。结果发现,样本男性青少年的血清IGF-1浓度在9-12岁以前升高不明显,12-13岁骤然升高,15岁达到最高峰后,缓慢下降;样本男性青少年在青春发育前期运动训练组与非运动训练组和青春发育后期运动训练组与非运动训练组血清IGF-1浓度无显著性差异。提示运动训练并未影响血清IGF-1的分泌规律。除体脂外,样本所有的生长发育指标均与IGF-1有正相关关系。垂直跳高度,连续跳高度在运动训练组与非运动训练组之间均存在显著性差异,并与血IGF-1水平呈正相关。     

谈孟子式的论辩逻辑

孟子以善辩、好辩著称,他的论辩主要靠气势;他有时也很讲究运用逻辑。但是,他的逻辑并不严密、不谨细,时有粗疏。     

短跑运动员跟腱生物力学特性的实验研究

通过对短跑运动员和非运动员跟腱弹性模量和刚度的比较研究。探讨短跑运动对人体跟腱生物力学特性的影响。研究结果表明,短跑训练后跟腱的弹性模量和刚度明显增加,提示训练能够改善跟腱的力学性能,表明训练后既能增加跟腱的体能储备,又能使其承受更大的载荷,并在一定程度上可减少跟腱疲劳损伤的发生．     

牵拉运动的神经生物学基础及其在运动训练中的应用

通过介绍肌纤维和肌腱内的本体感受器——肌梭和高尔基腱器官的结构及工作机制，了解牵拉的神经生物学原理，从而对牵拉的重要性有更进一步的认识，在体育教学和训练中正确应用牵拉、普遍推广牵拉，真正达到运动前热身、避免运损伤或运动后预防肌肉酸痛、减缓疲劳的效果。