Effects of Creep and Cyclic Loading on the Mechanical Properties and Failure of Human Achilles Tendons

The Achilles tendon is one of the most frequently injured tendons in humans, and yet the mechanisms underlying its injury are not well understood. This study examines the ex vivo mechanical behavior of excised human Achilles tendons to elucidate the relationships between mechanical loading and Achilles tendon injury. Eighteen tendons underwent creep testing at constant stresses from 35 to 75 MPa. Another 25 tendons underwent sinusoidal cyclic loading at 1 Hz between a minimum stress of 10 MPa and maximum stresses of 30–80 MPa. For the creep specimens, there was no significant relationship between applied stress and time to failure, but time to failure decreased exponentially with increasing initial strain (strain when target stress is first reached) and decreasing failure strain. For the cyclically loaded specimens, secant modulus decreased and cyclic energy dissipation increased over time. Time and cycles to failure decreased exponentially with increasing applied stress, increasing initial strain (peak strain from first loading cycle), and decreasing failure strain. For both creep and cyclic loading, initial strain was the best predictor of time or cycles to failure, supporting the hypothesis that strain is the primary mechanical parameter governing tendon damage accumulation and injury. The cyclically loaded specimens failed faster than would be expected if only time-dependent damage occurred, suggesting that repetitive loading also contributes to Achilles tendon injuries. © 2003 Biomedical Engineering Society. PAC2003: 8719Rr     

Effects of active recovery on power output during repeated maximal sprint cycling

The effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output ( ) during sprint 2, compared with passive recovery [ ] 603 (17) W and 589 (15) W, P < 0.05]. This improvement was totally attributed to a 3.1 (1.0)% higher power generation during the initial 10 s of sprint 2 following the active recovery (P < 0.05), since power output during the last 20 s sprint 2 was the same after both recoveries. Despite the higher power output during sprint 2 after active recovery, no differences were observed between conditions in venous blood lactate and pH, but peak plasma ammonia was significantly higher in the active recovery condition [205 (23) vs 170 (20) μmol · 1⁻¹;P < 0.05]. No differences were found between active and passive recovery in terms of changes in plasma volume or arterial blood pressure throughout the test. However, heart rate between the two 30-s sprints and oxygen uptake during the second sprint were higher for the active compared with passive recovery [148 (3) vs 130 (4) beats · min⁻¹;P < 0.01) and 3.3 (0.1) vs 2.8 (0.1) 1 · min⁻¹;P < 0.01]. These data suggest that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints. The beneficial effects of an active recovery are possibly mediated by an increased blood flow to the previously exercised muscle.     

特种兵高强度训练后集训疲劳行为的观察与防护

目的：改善与防护某特种兵队员高强度集训疲劳。方法：匀衡膳食营养,服用自制抗疲I号,分析血中酶等及SCL－90分值变化。结果：防护后血中LDH,α－HBDH,CK,CK－MB等得到明显改善IP＜0．01,0．05）,3例过度训练综合征得到防治,SCL－90显示：躯体化症状,强迫症状,睡眠饮食等分值整体呈下降趋势（P＜0．05,0．01）。结论：服用1号食品可有效防护过度训练综合征的发生,改善大强度体能,野战条件下各种军事课目集训产生的躯体和心身疲劳。     

中枢性疲劳症候群临床与血清色氨酸的研究

目的：对珠海市中学生中枢性疲劳症候群的临床,患病率及与血清色氨酸的关系进行研究。方法：采用单纯随机抽样和整群一级抽样方法,对4年中学1594人进行问卷调查作为初筛,筛出有症状的部分人在医院进行以排除其它疾病为 的精查,并做血清色氨酸含量的测量,结果：临床表现自主神经症状,睡眠障碍,精神症状,推测珠海市中学生中患病率为11％,血清色氨酸含量较正常对照组低,两组有显著差异（P＜0．01）,结论：中枢性疲劳症候群是珠海地区中学生中的常见病,应积极于以防治;血中色氨酸含量的测定对诊断该疾病有一定的价值。     

Clinical outcome after surgery on schwannomas in the extremities

BACKGROUND Schwannoma is a benign, encapsulated and slowly growing tumor originating from Schwann cells and is rarely seen in the peripheral nerve system. Typical symptoms are soreness, radiating pain and sensory loss combined with a soft tissue mass.AIM To evaluate pre-and postoperative symptoms in patients operated for schwannomas in the extremities and investigate the rate of malignant transformation.METHODS In this single center retrospective study design, all patients who had surgery for a benign schwannoma in the extremities from May 1997 to January 2018 were included. The location of the tumor in the extremities was divided into five groups; forearm, arm, shoulder, thigh and leg including foot. The locations of the tumor in the nerves were also categorized as either; proximal, distal, minor or major nerve. During the pre-and postoperative clinical evaluation, symptoms were classified as paresthesia, local pain, radiating pain, swelling, impairment of mobility/strength and asymptomatic tumors that were found incidentally(with magnetic resonance imaging). The patients were evaluated after surgery using the following categories: Asymptomatic or symptomatic patients(radiating and/or local pain) and those with complications. The follow up period was from the time of surgery until last examination of the particular physician. Multivariate logistic regression analysis was performed to identify independent prognostic factors for postoperative significant symptoms at follow-up.RESULTS We identified 858 cases from the institutional pathology register. We excluded cases with duplicate diagnoses(n = 407), pathology not including schwannomas(n = 157), lesions involving the torso, spine and neck(n = 150) leaving 144 patients for further analysis. In this group 99 patients underwent surgery and there were five complications recorded: 2 infections(treated with antibiotics) and 3 nerve palsies(2 involving the radial nerve and one involving the median nerve) that recovered spontaneously. At the end of follow-up, 1.4 mo(range 0.5-76) postoperatively, we recorded a post-operative decrease in clinical symptoms: Local pain 76%(6/25), radiating pain 97%(2/45), swelling 20%(8/10). Symptoms of paresthesia increased by 2.8%(37/36) and there was no change in motor weakness before and after surgery 1%(1/1). Multivariate analysis showed that tumors located within minor nerves had a significantly higher prevalence of postoperative symptoms compared with tumors in major nerves(odds ratio: 2.63; confidence intervals: 1.22-6.42, P = 0.029). One patient with schwannoma diagnosed by needle biopsy was diagnosed to have malignant transformation diagnosed in the surgically removed tumor. No local recurrences were reported.CONCLUSION Surgery of schwannomas can be conducted with low risk of postoperative complications, acceptable decrease in clinical symptoms and risk of malignant transformation is low.     

基于超声的2型糖尿病患者迷走神经病变分析

目的 了解2型糖尿病患者迷走神经病变,从而为糖尿病神经病变临床诊疗提供参考依据。方法 收集2020年1月—2021年6月在南京医科大学附属无锡人民医院内分泌科接受诊治的51例2型糖尿病患者和42例健康志愿者临床资料进行分析。采用自主神经症状（SAS）量表对2型糖尿病患者自主神经系统症状进行评价;采用超声测定迷走神经横断面面积,比较2型糖尿病患者和健康对照迷走神经横断面面积差异,分析迷走神经横断面面积与2型糖尿病患者临床特征间的关联。结果 2型糖尿病患者和健康对照者性别构成、年龄、身高、有吸烟史比例差异均无统计学意义（P > 0.05）,但2组研究对象体质量（t = 4.52,P < 0.01）、体质指数差异有统计学意义（t = 5.21,P < 0.01）。51例2型糖尿病患者中,37例出现自主神经系统症状,平均出现3.7 ±0.9种（1～9种）自主神经系统症状,总体症状影响评分平均为10.5 ±3.2分（0～25分）。2型糖尿病患者左、右侧迷走神经横断面面积平均为（1.55 ±0.44）、（1.97 ±0.66） mm²,显著大于健康对照的（1.37 ±0.37）、（1.61 ±0.540） mm²（t = 2.20,P < 0.05;t = 2.87,P < 0.01）。Pearson相关分析显示,迷走神经横断面面积与2型糖尿病患者及健康对照年龄、身高、体质量、体质指数均无统计学关联（P > 0.05）,且与2型糖尿病患者糖尿病病程、自主神经系统症状数量及SAS量表总体症状影响评分均无统计学关联（P > 0.05）。结论 2型糖尿病患者存在迷走神经增粗,迷走神经超声可用于自主神经病变早期检测。     

军人心理弹性与疲劳的关系：社会支持与自我效能感的多重中介作用

目的 研究军人疲劳与心理弹性、社会支持以及自我效能感的关系。方法 采用多维疲劳量表(Multidimensional fatigue inventory scale, MFI-20),心理弹性量表(The Connor-Davidson Resilience scale, CD-RISC),一般自我效能感量表(General Self Efficacy Scale, GSES),中文版社会支持问卷(Chinese Version Social support revalued scale, SSRS)对812名军人进行测试。采用相关性分析,回归分析探讨变量间的关系并通过建构结构方程模型检验社会支持、自我效能感在心理弹性与疲劳之间的中介作用。结果 共回收到794份有效问卷,有效率为97.78%。相关性结果分析表明疲劳与心理弹性、社会支持以及自我效能感负相关(P < 0.01),心理弹性与社会支持、自我效能感正相关(P < 0.01), 社会支持与自我效能感正相关(P < 0.01)。回归分析结果表明心理弹性可独立预测疲劳水平(P < 0.001),同时社会支持和自我效能感对疲劳的回归显著(P < 0.001),三者可解释疲劳46.6%的方差变异。结构方程模型结果表明社会支持、自我效能感在心理弹性与疲劳之间的中介作用显著(P = 0.026,P < 0.001, 95%置信区间都不包含0),同时,两者的链式中介在心理弹性与疲劳的也存在显著中介作用(P < 0.001, 95%置信区间都不包含0)。结论 加强军人心理弹性水平训练,增强军人社会支持水平,提高军人自我效能感对军人增强疲劳应对能力,降低疲劳反应,提高作业效能具有重要意义。     

"Fatigue on rest" and associated symptoms (headache, vertigo, blurred vision, nausea, tension and irritability) due to locally asymptomatic, unerupted, impacted teeth.

"Fatigue on Rest", headache, vertigo and the feeling of loss of balance, blurred vision, nausea, tension and irritability, were found to be prevalent amongst patients who had locally asymptomatic, unerupted impacted teeth. A comparative pressure sign was developed, which, when positive, confirmed the relationship between the impacted teeth and the medical symptoms. Removal of the impactions resulted in the alleviation of the symptoms. Stress and psychogenic factors are considered as trigger mechanisms, rather than as basic causes of the symptoms.     

中枢、神经—肌肉接头、肌肉疲劳的实验模型及其应用研究

目的：建立研究中枢、神经－肌肉接头和肌肉疲劳动物模型,为各种因素对运动性疲劳的影响及机制的研究,提供一种新的实验方法。方法：用铂金电极刺激蟾蜍脊髓,保护电极刺激坐骨神经干,直刺电极刺激腓肠肌,用MS302实验系统记录坐骨神经干的动作电位和腓肠肌的收缩曲线。观察丹参和生脉注射液对上述疲劳的影响。结果：中枢出现疲劳时间最短;神经－肌肉接头次之;肌肉出现疲劳时间最长。丹参和生脉注射液使中枢、神经－肌肉接头和肌肉出现疲劳时间都相应延长。结论：运动性疲劳首先发生在中枢,其次是神经－肌肉接头,最后是肌肉疲劳,丹参和生脉具有抗疲劳的作用。     

Partners in adversity V: Support,personality and coping behaviour at the time of crisis

This paper presents further results from a study of married women in Edinburgh who had just suffered an adverse experience: either their husband's non-fatal myocardial infartion, their husband's death or their own arrival in a Women's Aid refuge for battered women. Interviews were carried out 4–6 weeks following the adverse experience and, where possible, again approximately 3 months later. Symptoms were assessed using the 30-item General Health Questionnaire and criterion-based measures of depression and anxiety derived from it. The extent and nature of crisis support from household members and from groups of people outside the household, and also of failures in expected support, was measured at first interview. A modified version of Tyrer and Alexander's (1979) personality schedule was administered at the follow-up interview, and the resulting personality data were then reduced to six factors using principal components analysis. An interviewer assessment of how well the subject was coping was made at both interviews. The vast majority of the sample received extensive practical and emotional support from family and friends, and perhaps because such positive support was so prevalent, variations in it seemed to have little effect on symptoms. However, subjects who were unexpectedly let down or criticised by friends or family tended to show higher symptom levels, although, surprisingly, this was less true for the bereaved wives than for the others. The six personality factors that emerged were labellednervousness (similar to neuroticism)impulsivity, social withdrawal, helplessness, inferiority andaggressiveness. There was evidence that subjects high on nervousness remained symptomatic longer following the adverse experience. The aggressiveness factor showed a curvilinear trend with high and low aggressives showing higher symptom levels than middle aggressives. However, for the coronary wives the trend was linear with low aggressives having high symptoms. Subjects low on impulsivity were more affected by being let down by friends and family. The interviewer-assessed coping measure was linearly related to nervousness and showed a curvilinear relationship with aggressiveness.