The effects of dorso-lumbar motion restriction on energy use and center of mass movement during running

The effects of restricting dorso-lumbar spine mobility on oxygen consumption in runners was investigated, as was vertical movement of the body's center of mass. Thermoplastic casting material was fashioned into a rigid orthosis and used to restrict spinal motion during running. Volunteers ran on a treadmill at 2.78 m/sec, under normal conditions and with spinal motion restricted. Oxygen consumption was assessed via a Douglas bag set-up. Separately, vertical movement of the center of mass was assessed with a Panasonic recorder.ResultsCasted running resulted in an increase in oxygen consumption (p < 0.01). Casted running resulted in less vertical movement of the body's center of mass (p < 0.01).ConclusionsSpinal mobility has statistically significant effects on the energy used during running and on the vertical movement of the center of mass. A running style that causes the body to use more energy is inefficient and can lead to earlier onset of fatigue. It can make the runner more prone to overuse injuries. We hypothesize that less movement of the center of mass vertically can affect stride length, lead to more strides being used to cover a specific distance and thus could contribute to earlier onset of fatigue and overuse injury. More research needs to be done on this topic.     

Effects of spinal cord injury level on the activity of shoulder muscles during wheelchair propulsion: an electromyographic study

OBJECTIVE: To determine the influence of spinal cord injury (SCI) level on shoulder muscle function during wheelchair propulsion. DESIGN: Fine-wire electromyographic activity of 11 muscles was recorded during wheelchair propulsion. SETTING: Biomechanics research laboratory. PARTICIPANTS: Convenience sample of 69 men, in 4 groups by SCI level (low paraplegia, n=17; high paraplegia, n=19; C7-8 tetraplegia, n=16; C6 tetraplegia, n=17). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Timing of muscle activity onset, cessation, and duration, and time of peak intensity for each functional group were compared with 1-way analysis of variance. Median electromyographic intensity was also compared. RESULTS: Two functional synergies were observed: push (anterior deltoid, pectoralis major, supraspinatus, infraspinatus, serratus anterior, biceps) and recovery (middle and posterior deltoid, supraspinatus, subscapularis, middle trapezius, triceps). Push phase activity began in late recovery and ceased in early to late push. Recovery phase muscles functioned from late push to late recovery. Recruitment patterns for the groups with paraplegia were remarkably similar. For subjects with tetraplegia, pectoralis major activity was significantly prolonged compared with subjects with paraplegia (P<.05). Subscapularis activity shifted from a recovery pattern in subjects with paraplegia to a push pattern in persons with tetraplegia. CONCLUSIONS: Level of SCI significantly affected the shoulder muscle recruitment patterns during wheelchair propulsion. Differences in rotator cuff and pectoralis major function require specific considerations in rehabilitation program design.     

The effect of three levels of foot orthotic wedging on the surface electromyographic activity of selected lower limb muscles during gait

Background. Some types of foot orthoses have been researched for their effect on lower limb electromyographic muscle activity during walking. However, foot orthoses with high levels of medial rearfoot wedging (‘inverted’ foot orthoses) have not been investigated.

Methods. In a cross-sectional study, asymptomatic participants with a pronated foot type (n = 15) were each issued with a pair of 0°, 15° and 30° inverted custom-made foot orthoses. After four weeks of habituation to the orthoses, surface electromyography was used to measure the onset and maximum EMG amplitude of tibialis anterior, peroneus longus, medial gastrocnemius and soleus muscles using five conditions [barefoot, shoe-only, 0°, 15° and 30° inverted foot orthoses conditions].

Findings. A statistically significant increase in tibialis anterior maximum EMG amplitude occurred using the shoe only (30% increase), 0° (33% increase), 15° (38% increase) and 30° (30% increase) inverted orthoses conditions compared to walking barefoot (P < 0.01). Peroneus longus maximum EMG amplitude increased significantly using the 15° inverted orthosis condition compared to walking barefoot (21% increase, P = 0.04).

Interpretation. Footwear and orthoses can significantly alter the maximum EMG amplitude of leg muscles during walking. Foot orthoses appear to increase peroneus longus EMG amplitude compared to footwear alone. However, the level of medial rearfoot posting within an orthosis does not appear to significantly alter maximum EMG amplitude. The individual responses to foot orthoses are highly variable. The changes in EMG amplitude with the use of foot orthoses and shoes may have clinical implications.     

电刺激小脑顶核对缺血/再灌注大鼠脑组织内NF-κB活性及其活化的影响

目的 观察Wistar大鼠局灶脑缺血／再灌注后，脑内核因子—κB（NF—κB）活性及其活化的基本规律，并探讨电刺激小脑顶核（FNS）对其影响。方法成年雄性Wistar大鼠27只，随机分为正常组、单纯局灶脑缺血／再灌注组（模型组）和局灶脑缺血／再灌注＋电刺激小脑顶核治疗组（FNS治疗组）。采用线栓法制备右侧大脑中动脉闭塞（MCAO）模型，缺血时间均为2h，根据再灌注时间分为缺血2h／再灌注3，6，12和24h组？模型组不给予任何干预处理，FNS治疗组在缺血2h再灌注即刻给予FNS治疗1h。用Westernblot法检测缺血脑组织核抽提物中NF—κBp65蛋白的表达，用电泳迁移率改变分析法（EMSA）检测核抽提物中NF—κBDNA的结合活性=结果正常组大鼠脑组织核抽提物中有少量NF—κBp65蛋白，NF—κBDNA结合活性较弱。模型组再灌注各时间点，即再灌注3，6，12和24h，NF—κBp65蛋白含量均高于正常组，其中再灌注6h和12h均显著高于正常组（P〈0．05）。模型组NF—κBp65蛋白含量变化趋势为：再灌注3h〈再灌注6h〈再灌注12h，再灌注12h达峰值，各组间差异具有统计学意义（P〈0．05）；再灌注24h时NF—κBp65蛋白含量明显低于再灌注6h和12h（P〈0．05）。模型组NF—κBDNA结合活性除再灌注3h外，其余3个时间点均显著高于正常组（P〈0．05）；模型组再灌注3h时，NF—κBDNA结合活性明显弱于组内其余3个时间点（P〈0．05），这3个时间点均为高活性状态，组内差异无统计学意义（P〉0．05）。FNS治疗组NF—κBp65蛋白含量及NF—κBDNA结合活性的变化趋势与模型组相似。其中，再灌注6h和12h时，FNS治疗组NF—κBp65蛋白含量明显低于模型组相应时间点（P〈0．05）；再灌注6，12和24h时，FNS治疗组NF—κBDNA结合活性也明显低于模型组相应时间点（P〈0．05）。结论大鼠局灶脑缺血／再灌注后缺血脑组织中NF—κB活化明显，活性增强；FNS可下调NF—κB活化程度，抑制NF—κBDNA结合活性，这可能是FNS具有“抗炎”作用的重要机理之一。