不同植物生长调节剂对益母草愈伤组织诱导的影响

以益母草茎段、叶片两种外植体诱导产生愈伤组织．在MS培养基上,试验不同种类、不同浓度的植物生长调节剂及其组合对益母草茎段和叶片愈伤组织诱导的影响．结果表明：茎段愈伤组织诱导的较适培养基是MS附加6-BA3mg／L＋NAA1mg／L,诱导率为65％;叶片愈伤组织诱导的较适培养基是MS附加6-BA2mg／L＋NAA1mg／L,诱导率为80％．对益母草茎段和叶片外植体愈伤组织进行诱导,可为进一步研究益母草的组织培养和植株再生提供实验依据．     

正交试验法优选金线莲总黄酮的提取工艺

为了从金线莲中提取总黄酮,采用正交试验法研究金线莲总黄酮的提取工艺,考察了乙醇溶液的浓度,浸提温度,浸提时间,浸提次数,液料比5个因素对金线莲总黄酮提取率的影响。确立了金线莲总黄酮最佳提取条件为：用60％的乙醇溶液作溶剂,液料比20：1,浸提温度为80℃,回流提取3次,提取时间为每次40分钟。     

关于四种弱BCI-代数及其可分配性

引入比BCI-代数条件更弱的四种弱BCI-代数,讨论它们的等价条件,并给出弱BCI-代数的一种二元运算“＋”：x＊y=x＋（x＊y）,讨论了与这种运算相关的可分配性,进而四种弱BCI-代数在可分配下得到统一．     

上肢康复机器人主动康复训练控制策略

近年来,脑卒中和交通事故造成上肢损伤的人数逐年上升,医疗领域对康复器械的需求越来越大。为满足实际需求,开发以气动人工肌肉为驱动器的4自由度（肩关节外收/内展（被动）、前驱/后伸、肘关节屈曲、腕关节屈曲）可穿戴上肢康复机器人。首先设计上肢康复机器人的结构,并采用气动人工肌肉作为肘关节与腕关节的驱动器。然后针对该上肢康复机器人,研究主动康复训练控制策略,设计两种控制策略。通过穿戴实验验证控制策略的有效性和实际应用价值。     

Physiological responses in different intensities of resistance exercise – Critical load and the effects of aging process

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO₂) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La^?]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.     

Combined effects of exposure to hypoxia and cool on walking economy and muscle oxygenation profiles at tibialis anterior

We investigated combined effects of ambient temperature (23°C or 13°C) and fraction of inspired oxygen (21%O₂ or 13%O₂) on energy cost of walking (C_w: J·kg^?1·km^?1) and economical speed (ES). Eighteen healthy young adults (11 males, seven females) walked at seven speeds from 0.67 to 1.67 m s^?1 (four min per stage). Environmental conditions were set; thermoneutral (N: 23°C) with normoxia (N: 21%O₂) = NN; 23°C (N) with hypoxia (H: 13%O₂) = NH; cool (C: 13°C) with 21%O₂ (N) = CN, and 13°C (C) with 13%O₂ (H) = CH. Muscle deoxygenation (HHb) and tissue O₂ saturation (StO₂) were measured at tibialis anterior. We found a significantly slower ES in NH (1.289 ± 0.091 m s^?1) and CH (1.275 ± 0.099 m s^?1) than in NN (1.334 ± 0.112 m s^?1) and CN (1.332 ± 0.104 m s^?1). Changes in HHb and StO₂ were related to the ES. These results suggested that the combined effects (exposure to hypoxia and cool) is nearly equal to exposure to hypoxia and cool individually. Specifically, acute moderate hypoxia slowed the ES by approx. 4%, but acute cool environment did not affect the ES. Further, HHb and StO₂ may partly account for an individual ES.     

我国男生引体向上“零”分探因:基于三角互证的研究策略

我国多数男生引体向上得"零"分,使上肢力量测评出现"地板效应"。采用量化研究和质性研究两种范式提高研究效度。量化研究对学生体质与健康调研数据和监测数据进行方差分析、多重比较和回归分析,结果表明：（1）每5~10年,男生的握力、体重、身高、BMI、引体向上均值差异显著;（2）年龄、握力、体重、身高、BMI分别显著预测引体向上成绩,体重和握力是影响我国男生引体向上成绩的主要影响因素。质性研究结果表明,引体向上"零"分主要有四个方面的原因：体重增长难挡,力量增长受限,个体认知偏差,社会支持薄弱。结论：我国男生引体向上"零"分的首要原因是体重增长较快,其次,主要肌群绝对力量和耐力增长不足,男生对引体向上的认知有偏差,学校、家长、社会支持较弱;借助政策控制体重、发展肌力、完善测评标准、促进男生积极练习引体向上十分重要。     

Specific tackling situations affect the biomechanical demands experienced by rugby union players

Tackling in Rugby Union is an open skill which can involve high-speed collisions and is the match event associated with the greatest proportion of injuries. This study aimed to analyse the biomechanics of rugby tackling under three conditions: from a stationary position, with dominant and non-dominant shoulder, and moving forward, with dominant shoulder. A specially devised contact simulator, a 50-kg punch bag instrumented with pressure sensors, was translated towards the tackler (n = 15) to evaluate the effect of laterality and tackling approach on the external loads absorbed by the tackler, on head and trunk motion, and on trunk muscle activities. Peak impact force was substantially higher in the stationary dominant (2.84 ± 0.74 kN) than in the stationary non-dominant condition (2.44 ± 0.64 kN), but lower than in the moving condition (3.40 ± 0.86 kN). Muscle activation started on average 300 ms before impact, with higher activation for impact-side trapezius and non-impact-side erector spinae and gluteus maximus muscles. Players’ technique for non-dominant-side tackles was less compliant with current coaching recommendations in terms of cervical motion (more neck flexion and lateral bending in the stationary non-dominant condition) and players could benefit from specific coaching focus on non-dominant-side tackles.     

Tribute to Dr Jacques Rogge: muscle activity and fatigue during hiking in Olympic dinghy sailing

‘A tribute to Dr J. Rogge’ aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi-isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge’s merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee, he was also an orthopaedic surgeon and a keen sailor, competing at three Olympic Games. In 1972, in fulfilment of the requirements for the degree of Master in Sports Medicine, he was the first who studied a sailors’ muscle activity by means of invasive needle electromyography (EMG) during a specific sailing technique (hiking) on a self-constructed sailing ergometer. Hiking is a bilateral and multi-joint submaximal quasi-isometric movement which dinghy sailors use to optimize boat speed and to prevent the boat from capsizing. Large stresses are generated in the anterior muscles that cross the knee and hip joint, mainly employing the quadriceps at an intensity of 30–40% maximal voluntary contraction (MVC), sometimes exceeding 100% MVC. Better sailing level is partially determined by a lower rate of neuromuscular fatigue during hiking and for ≈60% predicted by a higher maximal isometric quadriceps strength. Although useful in exercise testing, prediction of hiking endurance capacity based on the changes in surface EMG in thigh and trunk muscles during a hiking maintenance task is not reliable. This could probably be explained by the varying exercise intensity and joint angles, and the great number of muscles and joints involved in hiking.

Highlights

• Dr Jacques Rogge, former president of the International Olympic Committee and Olympic Finn sailor, was the first to study muscle activity during sailing using invasive needle EMG to obtain his Master degree in Sports Medicine at the Ghent University.

• Hiking is a critical bilateral and multi-joint movement during dinghy racing, accounting for >60% of the total upwind leg time. Hiking generates large stresses in the anterior muscles that cross the knee and hip joint.

• Hiking is considered as a quasi-isometric bilateral knee extension exercise. Muscle activity measurements during sailing, recorded by means of EMG, show a mean contraction intensity of 30-40% maximal voluntary contraction with peaks exceeding 100%.

• Hiking performance is strongly related to the development of neuromuscular fatigue in the quadriceps muscle. Since maximal strength is an important determinant of neuromuscular fatigue during hiking, combined strength and endurance training should be incorporated in the training program of dinghy sailors.