THE VALIDITY OF PLANTARFLEXOR STRENGTH MEASURES OBTAINED THROUGH HAND‐HELD DYNAMOMETRY MEASUREMENTS OF FORCE

Purpose/Background:

Hand‐held dynamometers are commonly used to assess plantarflexor strength during rehabilitation. The purpose of this study was to determine the concurrent validity of measuring plantarflexion force using a hand‐held dynamometer (HHD) as compared to an electromechanical dynamometer as the gold standard. The hypothesis was that plantarflexor forces obtained using a hand‐held dynamometer would not show absolute agreement with a criterion standard.

Design:

Concurrent validity assessment for a diagnostic strength testing device.

Setting:

Institutional clinic and research laboratory

Participants:

Volunteer sample of healthy university students (N=20, 10 women, 10 men; 25.9±4.1 years).

Main Outcome Measure(s):

Maximal plantarflexion strength was measured using both a HHD and an electromechanical dynamometer (EMD) as a criterion measure.

Results:

Plantarflexor force measures with the HHD were significantly different (p<0.01) and not correlated with plantarflexor forces measured using the EMD for either limb (R² ≤ 0.09).

Conclusions:

Plantarflexor strength measurements acquired using HHD are different from those acquired using an EMD and are likely influenced by the strength of the examiner.

Level of Evidence:

Prospective cohort study, level II     

偏瘫患者膝关节伸屈肌等速肌力测试研究

目的了解偏瘫病人恢复独立行走后患肢和健肢的肌力、屈伸肌力比,探讨膝关节不稳定的原因.方法采用CybexNORM系统对10例脑卒中偏瘫病人进行膝伸、屈肌等速肌力测试.结果3种角速度60、120、180(°/8)向心和60°/s离心伸屈肌峰力矩平均值健侧均高于患侧,伸肌120°、180°/8和屈肌60°、180°/s健侧峰力矩显著高于患侧(P值均＜0.05),离心伸肌60°/s时(P＜0.05);离心收缩大于向心收缩,峰值比(H/Q)均在40%～70%范围.60°/s膝10°位向心和离心伸肌力矩健侧显著高于患侧(P均＜0.05).结论偏瘫病人伸、屈肌肌力不足是造成行走时患膝不稳(膝过伸)的重要原因.     

Neck flexor muscle fatigue is side specific in patients with unilateral neck pain.

Despite the evidence of greater fatigability of the cervical flexor muscles in neck pain patients, the effect of unilaterality of neck pain on muscle fatigue has not been investigated. This study compared myoelectric manifestations of sternocleidomastoid (SCM) and anterior scalene (AS) muscle fatigue between the painful and non-painful sides in patients with chronic unilateral neck pain. Myoelectric signals were recorded from the sternal head of SCM and the AS muscles bilaterally during sub-maximal isometric cervical flexion contractions at 25% and 50% of the maximum voluntary contraction (MVC). The time course of the mean power frequency, average rectified value and conduction velocity of the electromyographic signals were calculated to quantify myoelectric manifestations of muscle fatigue. Results revealed greater estimates of the initial value and slope of the mean frequency for both the SCM and AS muscles on the side of the patient's neck pain at 25% and 50% of MVC. These results indicate greater myoelectric manifestations of muscle fatigue of the superficial cervical flexor muscles ipsilateral to the side of pain. This suggests a specificity of the effect of pain on muscle function and hence the need for specificity of therapeutic exercise in the management of neck pain patients.     

Motor unit synchronization of the vasti muscles in closed and open chain tasks

OBJECTIVES: To investigate motor unit synchronization between medial and lateral vasti and whether such synchronization differs in closed and open chain tasks. DESIGN: Electromyographic recordings of single motor unit action potentials were made from the vastus medialis obliquus (VMO) and multiunit recordings from vastus lateralis during isometric contractions at 30 degrees of knee flexion in closed and open chain conditions. SETTING: Laboratory. PARTICIPANTS: Five volunteers with no history of knee pain (age, 30+/-3.32 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The degree of synchronization between motor unit firing was evaluated by identifying peaks in the electromyographic averages of the vastus lateralis, triggered from motor unit action potentials in the VMO, and the proportion of power in the power spectral density of the triggered average at the firing frequency of the reference motor unit. The proportion of cases in which there was significant power and peaks in the triggered averages was calculated. RESULTS: The proportion of trials with peaks in the triggered averages of the vastus lateralis electromyographic activity was greater than 61.5% in all tasks, and there was a significantly greater proportion of cases where power in the spectrum was greater than 7.5% ( P =.01) for the closed chain condition. CONCLUSIONS: There was a high proportion of synchronized motor units between the 2 muscles during isometric contractions, with evidence for greater common drive between the VMO and vastus lateralis in closed chain tasks. This has implications for rehabilitation because it suggests that closed chain tasks may generate better coordination between the vasti muscles.     

Influence of aging on isometric muscle strength,fat-free mass and electromyographic signal power of the upper and lower limbs in women

Background

Aging is a multifactorial process that leads to changes in the quantity and quality of skeletal muscle and contributes to decreased levels of muscle strength.

Objective

This study sought to investigate whether the isometric muscle strength, fat-free mass (FFM) and power of the electromyographic (EMG) signal of the upper and lower limbs of women are similarly affected by aging.

Method

The sample consisted of 63 women, who were subdivided into three groups (young (YO) n=33, 24.7±3.5 years; middle age (MA) n=15, 58.6±4.2 years; and older adults (OA). n=15, 72.0±4.2 years). Isometric strength was recorded simultaneously with the capture of the electrical activity of the flexor muscles of the fingers and the vastus lateralis during handgrip and knee extension tests, respectively. FFM was assessed using dual-energy X-ray absorptiometry.

Results

The handgrip strength measurements were similar among groups (p=0.523), whereas the FFM of the upper limbs was lower in group OA compared to group YO (p=0.108). The RMSn values of the hand flexors were similar among groups (p=0.754). However, the strength of the knee extensors, the FFM of the lower limbs and the RMSn values of the vastus lateralis were lower in groups MA (p=0.014, p=0.006 and p=0.013, respectively) and OA (p=0.000, p=0.000 and p<0.000, respectively) compared to group YO.

Conclusions

The results of this study demonstrate that changes in isometric muscle strength in MLG and electromyographic activity of the lower limbs are more pronounced with the aging process of the upper limb.     

Neuromuscular function of the latissimus dorsi muscle in goats after dynamic cardiomyoplasty

Skeletal muscle deterioration is emerging as a limitation to long-term cardiac assist by dynamic cardiomyoplasty. Chronic electrical stimulation of in situ skeletal muscle showed that ischemia, decreased muscle preload, muscle overuse, and chronic electrical stimulation are factors for muscle deterioration. Transposition around the heart has been associated with signs of muscle denervation after chronic electrical stimulation. To evaluate latissimus dorsi muscle neuromuscular function after longterm dynamic cardiomyoplasty, we performed neuromuscular functional analysis and histology on the latissimus dorsi muscle and thoracodorsal nerve of six normal goats and six goats after 6 months of dynamic cardiomyoplasty. Electromyographic analysis showed positive sharp waves and fibrillation potentials in the latissimus dorsi of three goats from the dynamic cardiomyoplasty group. Conduction velocity of the thoracodorsal nerve of goats from the dynamic cardiomyoplasty group (58.32+/-9.80 m/s) was reduced compared to the goats from the control group (71.48+/-5.71 m/s, P = 0.02). Histologic changes in skeletal muscle were compatible with denervation. Loss of myelin sheaths, collapse of endoneurial connective tissue, and solitary foci of axonophagia and myelinophagia further documented severe injury to the thoracodorsal nerve in goats from the dynamic cardiomyoplasty group. The latissimus dorsi muscle wrap was denervated after long-term dynamic cardiomyoplasty. Traction on the neurovascular pedicle at each contraction of the transposed muscle may induce afferent axonal injury of the thoracodorsal nerve resulting in diminished muscular function.     

Influence of chronic hypoxemia on peripheral muscle function and oxidative stress in humans

Transient re-oxygenation of humans suffering from chronic obstructive pulmonary disease (COPD) allows the assessment of the consequences of chronic hypoxemia on peripheral muscle and metabolism apart from the effects of de-conditioning. The subjects performed maximal voluntary contractions (MVC) of flexor digitorum and vastus lateralis muscles and sustained infra-maximal contractions. COPD patients repeated the whole challenge during a 50-min oxygen breathing period and after recovery to baseline hypoxemia. We measured the compound evoked muscle mass action potential (M-wave) and the medium frequency (MF) of surface electromyography (EMG) power spectrum. Blood lactate (LA) and potassium (K+), erythrocyte-reduced glutathione (GSH), and plasma thiobarbituric acid reactive substances (TBARS) were also measured. Compared with a control group, COPD patients had lower MVCs, an attenuated decrease in MF during exercise, lower resting level of GSH, no posthandgrip TBARS increase and no GSH consumption. Reoxygenation (1) increased MVCs, (2) accentuated the MF decline and (3) elicited a posthandgrip TBARS increase and GSH consumption. Thus, we conclude that chronic hypoxemia exerts specific muscular effects: a reduced force production, an attenuated 'muscle wisdom', and the suppression of the exercise oxidative stress.     

下肢闭链等速肌力训练对脑卒中患者下肢肌肉功能及步行能力的影响

目的:观察下肢闭链等速肌力训练对脑卒中恢复期患者下肢肌肉功能及步行能力的影响。方法:采用随机数字法将60例初次发病的恢复期脑卒中偏瘫患者随机分为治疗组和对照组,每组30例。对照组采用Bobath为主的神经发育疗法,治疗组在此基础上增加偏瘫下肢闭链肌力训练,训练模式为普通等速离心/离心模式,连续治疗8周,每周治疗3次。治疗前后分别采用等速肌力测试训练仪的峰力矩(peak torque,PT)、相对峰力矩(peak torque/body weight,PT/BW)、屈膝肌峰力矩与伸膝肌峰力矩比值(Hamstring/quadriceps,H/Q)、总功率(total work,TW)、平均功率(average power,AP)对患肢肌肉功能情况进行分析;利用30秒坐起测试(30s chair-stand test,30CST)、计时站立起步测试(time-up-and-go,TUG)评价患者步态、步行能力。结果:连续训练8周后,2组患者膝关节伸屈肌肌肉功能评定指标均较治疗前明显提高(P0.05),相比对照组,治疗组提高更明显(P0.05)。TUG结果提示两种治疗方式都可以改进患者步行能力(P0.05),但治疗组效果更明显(P0.05)。30CST结果显示,两种治疗方式在治疗后都无明显改变(P0.05)。结论:采用闭链等速肌力训练方式能明显改善脑卒中恢复期患者下肢肌肉功能和步行能力,是脑卒中患者康复治疗的新选择。     

Lack of effect of moderate-duration static stretching on plantar flexor force production and series compliance

Background

The effects of an acute bout of moderate-duration static stretching on plantar flexor force production, series compliance of the muscle–tendon unit, and levels of neuromuscular activation were examined.

Methods

Eighteen active individuals (9 men and 9 women) performed four 45-s static plantar flexor stretches and a time-matched control of no stretch (where subjects remained seated in the dynamometer for 4 min with no stretch being performed). Measures of peak isometric moment, rate of force development, neuromuscular activation (interpolated twitch technique and electromyography), twitch force characteristics, passive moment during stretch, and tendon elongation during maximal voluntary contractions were taken before and after the stretching.

Findings

Despite a significant stress–relaxation response during stretch (9.3%, P < 0.01) there were no significant differences in peak isometric moment (P = 0.35; effect size 0.13), rate of force development (P = 0.93; effect size 0.01), neuromuscular activation (interpolated twitch: P = 0.86; electromyography: P = 0.09; effect size 0.02), or tendon elongation (P = 0.61; effect size 0.07) after stretching. Twitch characteristics were also unchanged after stretching, although there was a reduction in the rate of twitch torque relaxation (RR_t; P < 0.01).

Interpretation

The acute bout of moderate-duration static stretching did not impair the force generating capacity of the plantar flexors or negatively affect muscle–tendon mechanical properties. Static stretching may not always have detrimental consequences for force production. Thus, clinicians may be able to apply moderate-duration stretches to patients without risk of reducing muscular performance.     

不同恢复期脑卒中患者胫骨前肌和腓肠肌表面肌电信号的研究

目的：探讨脑卒中偏瘫患者恢复期sEMG信号的特点及规律。方法：17例偏瘫患者分为两组．A组9例均为BrunnstromⅣ期的患者，B组8例均为BrunnstromⅤ期的患者，在进行踝关节背屈最大自主收缩的同时，采用表面肌电图仪记录患侧和健侧的胫骨前肌和腓肠肌外侧头收缩的肌电信号，并对两组的积分肌电值、协同收缩率等观测指标进行分析比较。结果：B组患侧胫骨前肌积分肌电值明显高于A组（P〈0．01），B组患侧协同收缩率则明显低于A组（P〈0．01），而两组的患侧腓肠肌、健侧胫骨前肌、健侧腓肠肌积分肌电，以及健侧的协同收缩率之间差异无显著性（P〉0．05）;A、B两组的患侧与健侧胫骨前肌积分肌电、患侧与健侧协同收缩率之间均有不同程度的差异（P〈0．01或P〈0．05），而两组患侧与健侧腓肠肌积分肌电之间差异均无显著性（P〉0．05）。结论：恢复后期的偏瘫患者踝背屈主动肌的收缩功能及对拮抗肌协同收缩的控制能力明显好于恢复前期的偏瘫患者。sEMG作为一种简便的、非创伤性的检查方法，在脑卒中偏瘫运动功能评价中具有潜在的临床应用价值。     

Hip flexor muscle size,strength and recruitment pattern in patients with acetabular labral tears compared to healthy controls

Acetabular labral tears are a source of hip pain and are considered to be a precursor to hip osteoarthritis. Hip flexor muscles contribute to hip joint stability and function but it is unknown if their size and function is altered in the presence of labral pathology. This study aimed to investigate hip flexor muscle size, strength and recruitment pattern in patients with hip labral pathology compared to control subjects. 12 subjects diagnosed with an unilateral acetabular labral tear were compared to 12 control subjects matched for age and gender. All subjects underwent magnetic resonance imaging (MRI) of their lumbo-pelvic region. Average muscle cross-sectional area (CSA) of the iliacus, psoas, iliopsoas, sartorius, tensor fascia latae and rectus femoris muscles were measured. Hip flexion strength was measured by an externally fixed dynamometer. Individual muscle recruitment pattern during a resisted hip flexion exercise task was measured by muscle functional MRI.Hip flexor muscle strength was found to be decreased in patients with labral pathology compared to control subjects (p < 0.01). No difference between groups or sides was found for hip flexor muscle size (all p > 0.17) and recruitment pattern (all p > 0.53).Decreased hip flexor muscle strength may affect physical function in patients with hip labral pathology by contributing to altered gait patterns and functional tasks. Clinical rehabilitation of these patients may need to include strengthening exercises for the hip flexor muscles.     

功能性踝关节不稳的运动员与非运动员踝内外翻肌等速向心及等速离心测试的比较分析

目的:对功能性踝关节不稳(FAI)运动员与非运动员踝内外翻肌进行等速向心及等速离心测试的对比分析,为进一步康复提供依据。方法:使用BiodexSystem-3型等速肌力测试训练系统对35例运动员FAI患者及21例非运动员普通人群FAI患者分别进行踝关节内、外翻等速向心及离心(角速度均为30°/s×5次;180°/s×10次)的测试。结果:运动员FAI患者除了高角速度离心运动时,踝外翻肌群力矩低于同组健侧外,踝内、外翻肌群在低角速度向心、低角速度离心及高角速度向心的力矩均未低于健侧(P>0.05);而普通FAI患者存在踝内外翻肌群在各种角速度时普遍性肌力缺陷、关节活动度降低及I/E比值的升高(P<0.05)。结论:不同人群FAI患者力矩改变特点不同,选用等速仪器中I/E比值并作动态控制率的分析,有利于制定更有针对性的康复处方。     

急性下腰痛者竖脊肌和臀大肌功能变化的研究

目的：研究正常人诱发急性下腰痛前后竖脊肌和臀大肌在不同屈曲角度和负荷条件下矢状面前曲和后伸时肌肉的功能状况的变化。方法：无下腰痛病史的正常人7例。表面肌电图在双侧L3／L4、L5／S1水平竖脊肌和臀大肌进行采样。在不同用力程度和屈曲角度条件下行躯干背伸等长收缩运动，记录收缩力矩和L3／L4、L5／S1竖脊肌和臀大肌的表面肌电图信号。24小时后在L4／L5棘突间隙皮下注射1ml蒸馏水，5min后重复前日实验过程。结果：诱发下腰痛后，躯干背伸最大主动收缩力矩下降，疼痛VAS评分升高。在等长运动开始后30s内测量，所测肌的MPF值均升高，以双侧臀大肌升高最明显。MPF斜率值较诱发疼痛前无明显变化。L5／S1水平竖脊肌和臀大肌的RMS值下降，以双侧臀大肌下降最明显。结论：①皮下注射蒸馏水诱发急性下腰痛的方法，可用于急性下腰痛的实验研究。②急性下腰痛者在等长运动早期中竖脊肌和臀大叽的MPF斜率值较正常时上升，而RMS下降。可能与Ⅰ型纤维的募集增加有关。     

闭链离心等张训练对髌股疼痛综合征患者膝关节功能的影响

目的:探讨闭链离心等张训练对髌股疼痛综合征(PFPS)患者膝关节功能的疗效。方法:选取33例符合纳入排除标准的髌股疼痛综合征患者,采用随机数字表法分成试验组(n=17)和对照组(n=16);试验组采用常规康复训练+闭链离心等张训练,对照组仅进行常规康复训练。两组患者在治疗前、治疗8周采用视觉模拟评分法(VAS)评定患者疼痛程度、等速肌力测定膝伸屈肌群肌力、膝关节Kujala评分评价膝关节功能以及SF-36评估生存质量。结果:两组治疗8周后VAS评分低于治疗前(P0.05)、Kujala评分、60°/s速度下膝伸屈肌群峰力矩、SF-36中生理职能、躯体疼痛、一般健康状况改善,与治疗前比较差异有显著性意义(P0.05)。8周治疗后,试验组VAS评分低于对照组(P0.05)、Kujala评分、60°/s速度下膝伸屈肌群峰力矩及SF-36中生理职能、健康变化均高于对照组(P0.05)。结论:常规康复训练的基础上结合闭链离心等张训练能进一步缓解髌股疼痛综合征患者膝关节疼痛、增强肌力、提高生活满意度,建议可以作为PFPS康复训练的一部分,值得临床应用及推广。     

Plantarflexor muscle function in healthy and chronic Achilles tendon pain subjects evaluated by the use of EMG and PET imaging

Background

Achilles tendon pathologies may alter the coordinative strategies of synergistic calf muscles. We hypothesized that both surface electromyography and positron emission tomography would reveal differences between symptomatic and asymptomatic legs in Achilles tendinopathy patients and between healthy controls.

Methods

Eleven subjects with unilateral chronic Achilles tendon pain (28 years) and eleven matched controls (28 years) were studied for triceps surae and flexor hallucis longus muscle activity in response to repetitive isometric plantarflexion tasks performed at 30% of maximal voluntary contraction using surface electromyography and glucose uptake using positron emission tomography. Additionally, Achilles tendon glucose uptake was quantified.

Findings

Normalized myoelectric activity of soleus was higher (P < 0.05) in the symptomatic leg versus the contralateral and control legs despite lower absolute force level maintained (P < 0.005). Electromyography amplitude of flexor hallucis longus was also greater on the symptomatic side compared to the healthy leg (P < 0.05). Both the symptomatic and asymptomatic legs tended to have higher glucose uptake compared to the control legs (overall effect size: 0.9 and 1.3, respectively). Achilles tendon glucose uptake was greater in both legs of the patient group (P < 0.05) compared to controls. Maximal plantarflexion force was ~ 14% greater in the healthier leg compared to the injured leg in the patient group.

Interpretations

While the electromyography showed greater relative amplitude in the symptomatic leg, the results based on muscle glucose uptake suggested relatively similar behavior of both legs in the patient group. Higher glucose uptake in the symptomatic Achilles tendon suggests a higher metabolic demand.     

脑卒中患者桥式运动下竖脊肌与多裂肌表面肌电图信号特征研究

目的:观察脑卒中患者桥式运动下竖脊肌与多裂肌表面肌电(s EMG)信号变化特征,为桥式运动的临床应用提供电生理理论基础。方法:选取20例健康同龄成年人(正常组)与20例脑卒中偏瘫患者(患者组),对两组受试者行桥式运动时的竖脊肌与多裂肌s EMG信号参数进行比较分析。结果:1正常组双侧竖脊肌、多裂肌配对比较,时域指标平均肌电值(AEMG)、频域指标中位频率值(MF)均无显著性差异(P0.05);患者组竖脊肌患侧AEMG值大于健侧、患侧MF值均小于健侧,差异有显著性意义(P0.05);患者组双侧多裂肌AEMG值、MF值组内配对比较,差异无显著性意义。2两组受试者同侧竖脊肌与多裂肌AEMG值的比值差异无显著性意义(P0.05)。结论:桥式运动可作为脑卒中患者躯干肌训练的一种方法,但须注意训练时双侧竖脊肌的均衡性。     

Delayed open reduction and internal fixation of a neglected fracture dislocation of the ankle

Neglected fracture dislocations of ankle are rare in western countries. Failure to achieve anatomic reduction is associated with a poor prognosis. We present a case of a patient with a neglected Weber B fracture of the fibula with postero-lateral subluxation of the ankle. In theatre, the subluxation could not be reduced, and a posterior and lateral soft tissue release was performed. Granulation tissue was removed from the medial gutter. The fibular fracture was reduced and fixed with a six-hole dynamic compression plate. Post-operative radiographs was satisfactory and the patient was followed up for 12 months with full range of movement and function of the joint. In our case, correction was not obtained by osteotomy of the lateral malleolus alone, and medial and posterior soft tissue release was required. This was due to disruption of the deltoid ligament and posterior tibiofibular ligament and the associated scar tissue. Previous studies have shown that, if anatomic reduction is achieved, results with delayed surgery can be as good as those obtained with immediate surgery. Surgically correcting an old fracture dislocation is a difficult undertaking due to soft-tissue contractures and malunited fractures. It is important to preserve as much soft tissue attachments and periosteum to prevent avascular necrosis.     

开放式与密闭式吸痰的研究进展

对开放式与密闭式吸痰方法在吸痰过程中对患者的呼吸功能、氧合、血流动力学、分泌物的清除效果、以及对护士工作效率、护理成本、医院感染的不同作用和影响进行综述,以便找出最恰当科学的吸痰方式.     

Masseter and temporalis muscle EMG levels and bite force in migraineurs

The purpose of this study was to compare absolute and proportional electromyography (EMG) levels in the masseter and temporalis muscles during performance of a variety of oral functions for migraineurs and age- and sex-matched controls. Both groups consisted of nine women and one man, with a mean age of 43 years (range, 29 to 51 years). Absolute resting EMG levels and those levels during swallowing and speech were not significantly different between the groups, but the levels of the group with migraine were significantly higher during maximum voluntary effort contractions on the anterior teeth and on the posterior teeth for both muscles. When expressed as a percentage of those levels obtained at maximal posterior contraction (ie, proportional levels), no difference in functional activity was demonstrated between groups. It was concluded that the two groups studied had similar levels of EMG activity in the masseter and temporalis muscles during the normal oral functions investigated, but that the group with migraine had higher levels of absolute EMG activity during anterior and posterior maximum voluntary contractions. Furthermore, the group with migraine demonstrated higher levels of anterior and posterior bite force, although not correlated with EMG levels.