MOTOmed下肢运动训练联合等速肌力训练对脑卒中偏瘫患者下肢运动功能、下肢肌张力和步行步态功能的影响

摘要 目的：观察MOTOmed下肢运动训练联合等速肌力训练在脑卒中偏瘫患者的应用价值。方法：根据随机数字表法将2019年5月-2022年12月期间南京医科大学附属脑科医院收治的158例脑卒中偏瘫患者分为对照组（n=79,接受等速肌力训练）和观察组（n=79,对照组基础上接受MOTOmed下肢运动训练）。对比两组下肢运动功能、下肢肌张力、步行步态功能。结果：干预12周后,两组Fugl-Meyer运动功能评定量表（FMA）、Berg平衡量表（BBS）评分升高,且观察组高于对照组同期（P<0.05）。干预12周后,两组膝关节后伸（FKE）、前屈（FKF）、髋关节后伸（FHE）、前屈（FHF） 肌张力升高,且观察组高于对照组同期（P<0.05）。干预12周后,两组步速、步频、步长、功能性步行分级量表（FAC）评分升高,且观察组高于对照组同期（P<0.05）。结论：MOTOmed下肢运动训练联合等速肌力训练治疗脑卒中偏瘫患者,可有效改善下肢运动功能、下肢肌张力以及步行步态功能。     

The loss of dexterity in the bilateral lower extremities in patients with stroke

The aim of this study was to examine the dexterity of both lower extremities in patients with stroke. Twenty patients with stroke and 20 age-matched control subjects participated in this study. To determine the dexterity of the lower extremities, we examined the ability to control muscle force during submaximal contractions in the knee extensor muscles using a force tracking task. The root mean square errors were calculated from the difference between the target and response force. The root mean square error was significantly greater in the affected limb of patients with stroke compared with those of the unaffected limb and the control subjects, and in the unaffected limb compared with that of the control subjects. Furthermore, the root mean square error of the affected limb was related significantly to motor function as determined by Fugl-Myer assessment. These results demonstrate impairment of the dexterity of both the affected and the unaffected lower extremities in patients with stroke.     

Decreased rate of leg extensor force development in independently ambulant patients with acute stroke with mild paresis

We aimed to examine the rate of force development (RFD) of knee extensors on both sides in independently ambulant patients with acute stroke with mild paresis compared with that in age-matched healthy adults. A total 31 patients with acute stroke history (patient group: 67 ± 12 years) and 54 age-matched healthy, community-dwelling adults (control group: 67 ± 8 years) were included. Maximum voluntary contraction (MVC) and RFD were assessed <1 month post-stroke during isometric knee extension (sitting position; 90° knee flexion) using a hand-held dynamometer. RFD was measured as the average slope of the torque–time curve over time intervals of 0–50 ms and 0–200 ms from contraction onset. In the patient group, MVC and RFD for 0–50 ms were significantly lower on the affected side than on the unaffected side (p < 0.01). RFD was significantly decreased in the patient group, to 32%–38% and 62%–71% of that in the control group, over 0–50 ms and 0–200 ms, respectively, regardless of the affected side (p < 0.01). No significant differences in MVC between patient and control groups were observed for either side. RFD of the knee extensors significantly decreased without MVC reduction in patients with acute stroke history compared with that in age-matched healthy adults in both the affected and unaffected sides. These results suggest that decrease in RFD was initiated from the acute phase of stroke, even in patients with stroke who had good motor function.     

MOTOmed下肢智能运动训练联合运动想象疗法对脑卒中偏瘫患者下肢功能、步行能力和躯干屈伸肌群肌力的影响

摘要 目的：探讨MOTOmed下肢智能运动训练联合运动想象疗法对脑卒中偏瘫患者下肢功能、步行能力和躯干屈伸肌群肌力的影响。方法：148例脑卒中偏瘫患者来源于我院2019年5月~2021年5月期间我院接收的患者,根据随机数字表法分为对照组（n=74,常规康复训练的基础上结合MOTOmed下肢智能运动训练）和研究组（n=74,对照组的基础上结合运动想象疗法）。两组均干预12周。对比两组下肢功能、步行能力和躯干屈伸肌群肌力变化。结果：两组干预12周后Fugl-Meyer运动功能量表（FMA）、Barthel指数（BI）、功能性步行能力分级量表（FAC）评分升高,且研究组高于对照组（P<0.05）。两组干预12周后步频、步速、跨步长比率升高,且研究组高于对照组（P<0.05）。两组干预12周后健侧腹直肌、竖脊肌表面肌电信号的均方根值未见明显变化,且组间同时点对比无差异（P>0.05）。两组干预12周后患侧腹直肌、竖脊肌表面肌电信号的均方根值升高,且研究组高于对照组（P<0.05）。结论：脑卒中偏瘫患者在MOTOmed下肢智能运动训练的基础上进行运动想象疗法,可促进下肢功能改善,提高步行能力,同时还可改善患侧躯干屈伸肌群肌力。     

虚拟现实平衡训练联合神经肌肉电刺激对前交叉韧带重建术后患者膝关节功能、腘绳肌肌力和步行功能的影响

摘要 目的：探讨虚拟现实平衡训练联合神经肌肉电刺激（NMES）对前交叉韧带重建术（ACLR）后患者膝关节功能、腘绳肌肌力和步行功能的影响。方法：选择2019年8月~2021年12月期间我院收治的前交叉韧带（ACL）损伤患者96例,并成功实施ACLR,采用随机数字表法分为对照组（n=48,常规康复训练、虚拟现实平衡训练）和研究组（n=48,常规康复训练、虚拟现实平衡训练联合NMES干预）。对比两组膝关节功能优良率、膝关节功能、腘绳肌肌力和步行功能。结果：研究组的临床膝关节功能优良率93.75%（45/48）高于对照组68.75%（33/48）,差异有统计学意义（P<0.05）。两组干预后膝关节功能评分、膝关节活动度对均升高,且研究组高于对照组（P<0.05）。两组干预后患侧腘绳肌等长肌力升高,且研究组高于对照组（P<0.05）,两组干预后健侧腘绳肌等长肌力对比无明显差异（P>0.05）。两组干预后步长、步速升高,且研究组高于对照组,患侧摆动相降低,且研究组低于对照组（P<0.05）。两组干预后被动活动察觉阀值、进行被动角度再生试验降低,且研究组低于对照组（P<0.05）。结论：虚拟现实平衡训练联合NMES应用于ACLR术后患者的疗效显著,有助于其膝关节功能恢复,提高腘绳肌肌力,改善步行功能。     

等速肌力训练联合有氧运动对脑卒中患者肺功能、下肢运动功能及生活质量的影响

目的:探讨有氧运动联合等速肌力训练对脑卒中患者下肢运动功能、肺功能及生活质量的影响。方法:选取2016年8月～2019年9月期间我院收治的脑卒中患者130例,根据随机数字表法分为对照组(n=65,常规康复训练)和研究组(n=65,等速肌力训练联合有氧运动),比较两组患者肺功能、下肢运动功能及生活质量。结果:两组治疗8周后膝关节峰力矩(PT)、膝屈伸PT、膝屈伸耐力指数(ER)、Fugl-Meyer下肢运动功能量表(FMA-LE)评分均较治疗前升高,且研究组高于对照组(P0.05)。两组治疗8周后社会功能、躯体疼痛、精神健康、活力、健康状况、生理职能、生理机能、情感职能维度评分均较治疗前升高,且研究组高于对照组(P0.05)。两组治疗8周后用力肺活量(FVC)、第一秒用力呼气量(FEV1)、最大呼气流量(PEF)均较治疗前升高,且研究组高于对照组(P0.05)。结论:脑卒中患者给予等速肌力训练联合有氧运动,可有效改善其肺功能、下肢运动功能及生活质量,临床应用价值较高。     

Effects of Swiss-ball core strength training on strength, endurance, flexibility, and balance in sedentary women

The purpose of this study was to investigate the effects of Swiss-ball core strength training on trunk extensor (abdominal)/flexor (lower back) and lower limb extensor (quadriceps)/flexor (hamstring) muscular strength, abdominal, lower back and leg endurance, flexibility and dynamic balance in sedentary women (n = 21; age = 34 ± 8.09; height = 1.63 ± 6.91 cm; weight = 64 ± 8.69 kg) trained for 45 minutes, 3 d·wk-1 for 12 weeks. Results of multivariate analysis revealed significant difference (p ≤ 0.05) between pre and postmeasures of 60 and 90° s trunk flexion/extension, 60 and 240° s-1 lower limb flexion/extension (Biodex Isokinetic Dynamometer), abdominal endurance (curl-up test), lower back muscular endurance (modified Sorensen test), lower limb endurance (repetitive squat test), lower back flexibility (sit and reach test), and dynamic balance (functional reach test). The results support the fact that Swiss-ball core strength training exercises can be used to provide improvement in the aforementioned measures in sedentary women. In conclusion, this study provides practical implications for sedentary individuals, physiotherapists, strength and conditioning specialists who can benefit from core strength training with Swiss balls.     

肌内效贴镇痛联合康复训练对脑卒中偏瘫患者下肢运动功能、步行参数和生活质量的影响

目的:探讨肌内效贴镇痛联合康复训练对脑卒中偏瘫患者下肢运动功能、步行参数和生活质量的影响。方法:选取2017年1月-2018年1月期间我院收治的脑卒中偏瘫患者200例为研究对象。根据随机数表法将患者分为对照组(n=100)与观察组(n=100)。两组患者均接受常规康复训练,观察组在此基础上联合肌内效贴镇痛治疗。两组均治疗4周,观察并比较两组患者治疗前后下肢运动功能、步行参数和生活质量。结果:两组患者治疗后简化Fugl-Meyer运动功能量表(FMA-L)、徒手肌力测试(MMT)、Berg平衡量表(BBS)均较治疗前升高,且观察组高于对照组(P0.05);两组患者治疗后改良Ash-worth量表(MAS)、计时起立行走测试(TGUT)均较治疗前降低,且观察组低于对照组(P0.05)。两组患者治疗后步速、步幅、患侧步长、健侧步长、步态周期、双腿支撑期均较治疗前升高,且观察组高于对照组(P0.05);两组患者治疗后步态不对称指数较治疗前降低,且观察组低于对照组(P0.05)。两组患者治疗后Barthel指数(BI)较治疗前升高,且观察组高于对照组(P0.05)。结论:肌内效贴镇痛与康复训练联合治疗脑卒中偏瘫患者,疗效满意,可显著改善患者下肢运动功能、步行参数以及生活质量。     

Directional effect on post-stroke motor overflow characteristics

Motor overflow (MO) is an involuntary muscle activation associated with strenuous contralateral movement and may become manifested after stroke. The study was undertaken to investigate physiological correlation underlying atypical directional effect of joint movement on post-stroke MO in the affected upper limb. Thirty patients with unilateral post-stroke hemiparesis and fifteen age-matched healthy controls participated in this study. According to motor function assessed with the Fugl-Meyer arm scale, the patients were categorized into two groups of equal number with better (CVA_G; n = 15) or poorer motor functions (CVA_P; n = 15). Surface electromyography (EMG) was used to record irradiated muscle activation from eight muscles of the affected upper limb when the subjects performed maximal isometric contractions in different directions with the unaffected shoulder, elbow and wrist joints. The results showed that only MO amplitude of the CVA_G and the control groups was more sensitive to variations in direction of joint movement in the unaffected arm than the CVA_P group. The CVA_G group exhibited larger amplitudes of MO than the control analog, whereas this tendency was reversed for the CVA_P group. In terms of EMG polar plots, spatial representations of post-stroke MO were insensitive to direction of contralateral movement. The spatial representations of the CVA_G and CVA_P groups were predominated by potent flexion-abduction synergy, contrary to the typical extension adduction synergy seen in the control analog. In conclusion, post-stroke MO amplitude was subject to contralateral movement direction for healthy controls and stroke patients with better motor recovery. However, alterations in MO spatial pattern due to directional effect were not strictly related to the degree of motor deficits of the stroke victims.     

Joint moment contributions to swing knee extension acceleration during gait in children with spastic hemiplegic cerebral palsy

Inadequate peak knee extension during the swing phase of gait is a major deficit in individuals with spastic cerebral palsy (CP). The biomechanical mechanisms responsible for knee extension have not been thoroughly examined in CP. The purpose of this study was to assess the contributions of joint moments and gravity to knee extension acceleration during swing in children with spastic hemiplegic CP. Six children with spastic hemiplegic CP were recruited (age=13.4±4.8 years). Gait data were collected using an eight-camera system. Induced acceleration analysis was performed for each limb during swing. Average joint moment and gravity contributions to swing knee extension acceleration were calculated. Total swing and stance joint moment contributions were compared between the hemiplegic and non-hemiplegic limbs using paired t-tests (p<0.05). Swing limb joint moment contributions from the hemiplegic limb decelerated swing knee extension significantly more than those of the non-hemiplegic limb and resulted in significantly reduced knee extension acceleration. Total stance limb joint moment contributions were not statistically different. Swing limb joint moment contributions that decelerated knee extension appeared to be the primary cause of inadequate knee extension acceleration during swing. Stance limb muscle strength did not appear to be the limiting factor in achieving adequate knee extension in children with CP. Recent research has shown that the ability to extend the knee during swing is dependent on the selective voluntary motor control of the limb. Data from individual participants support this concept.     

Impaired Hyperemic Response to Exercise Post Stroke

Individuals with chronic stroke have reduced perfusion of the paretic lower limb at rest; however, the hyperemic response to graded muscle contractions in this patient population has not been examined. This study quantified blood flow to the paretic and non-paretic lower limbs of subjects with chronic stroke after submaximal contractions of the knee extensor muscles and correlated those measures with limb function and activity. Ten subjects with chronic stroke and ten controls had blood flow through the superficial femoral artery quantified with ultrasonography before and immediately after 10 second contractions of the knee extensor muscles at 20, 40, 60, and 80% of the maximal voluntary contraction (MVC) of the test limb. Blood flow to the paretic and non-paretic limb of stroke subjects was significantly reduced at all load levels compared to control subjects even after normalization to lean muscle mass. Of variables measured, increased blood flow after an 80% MVC was the single best predictor of paretic limb strength, the symmetry of strength between the paretic and non-paretic limbs, coordination of the paretic limb, and physical activity. The impaired hemodynamic response to high intensity contractions was a better predictor of lower limb function than resting perfusion measures. Stroke-dependent weakness and atrophy of the paretic limb do not explain the reduced hyperemic response to muscle contraction alone as the response is similarly reduced in the non-paretic limb when compared to controls. These data may suggest a role for perfusion therapies to optimize rehabilitation post stroke.     

低频重复经颅磁刺激联合等速肌力训练模式干预对脑卒中的影响

摘要 目的：探讨等速肌力训练与低频重复经颅磁刺激对脑卒中患者下肢肌力的影响。方法：选择2020年2月到2021年8月在本院住院诊治的脑卒中患者96例作为研究对象,采用完全随机化1：1信封抽签原则把患者分为联合组与对照组各48例。对照组给予等速肌力训练,联合组在对照组治疗基础上给予低频重复经颅磁刺激治疗。两组在4周后记录下肢肌力变化情况。结果：（1）两组治疗后的美国国立卫生院神经功能缺损评分（NIHSS）低于治疗前,联合组低于对照组（P<0.05）。（2）两组治疗后的简化Fugl-Meye下肢评分高于治疗前,联合组高于对照组（P<0.05）。（3）两组治疗后的120 °/s时膝关节的伸肌与屈肌峰力矩体重比都高于治疗前,联合组高于对照组（P<0.05）。（4）两组治疗后的运动诱发电位潜伏期低于治疗前,波幅高于治疗前,联合组与对照组对比有差异（P<0.05）。结论：等速肌力训练联合低频重复经颅磁刺激在脑卒中患者的应用能促进改善神经功能与运动诱发电位,从而提高患者的下肢肌力与运动能力。     

Altered kinetic strategy for the control of swing limb elevation over obstacles in unilateral below-knee amputee gait.

Our goal was to document the kinetic strategies for obstacle avoidance in below-knee amputees. Kinematic data were collected as unilateral below-knee traumatic amputees stepped over obstacles of various heights in the walking path. Inverse dynamics were employed to calculate power profiles and work during the limb-elevation and limb-lowering phases. Limb elevation was achieved by employing a different strategy of intra-limb interaction for elevation of the prosthetic limb than for the sound limb, which was similar to that seen in healthy adult non-amputees. As obstacle height increased, prosthetic side knee flexion was increased by modulating the work done at the hip, and not the knee, as seen on the sound side. Although the strength of the muscles about the residual knee was preserved, the range of motion of that knee had previously been found to be somewhat limited. Perhaps more importantly, potential instability of the interface between the stump and the prosthetic socket, and associated discomfort at the stump could explain the altered limb-elevation strategy. Interestingly, the limb-lowering strategy seen in the sound limb and in non-amputees already features modulation of rotational and translational work at the hip, so an alternate strategy was not required. Thus, following a major insult to the sensory and neuromuscular system, the CNS is able to update the internal model of the locomotor apparatus as the individual uses the new limb in a variety of movements, and modify control strategies as appropriate.     

Use of whole body vibration in individuals with chronic stroke: Transmissibility and signal purity

This study examined (1) the influence of whole body vibration (WBV) frequency (20 Hz, 30 Hz, 40 Hz), amplitude (low: 0.8 mm and high: 1.5 mm) and body postures (high-squat, deep-squat, tip-toe standing) on WBV transmissibility and signal purity, and (2) the relationship between stroke motor impairment and WBV transmissibility/signal purity. Thirty-four participants with chronic stroke were tested under 18 different conditions with unique combinations of WBV frequency, amplitude, and body posture. Lower limb motor function and muscle spasticity were assessed using the Fugl-Meyer Assessment and Modified Ashworth Scale respectively. Nine tri-axial accelerometers were used to measure acceleration at the WBV platform, and the head, third lumbar vertebra, and bilateral hips, knees, and ankles. The results indicated that WBV amplitude, frequency, body postures and their interactions significantly influenced the vibration transmissibility and signal purity among people with chronic stroke. In all anatomical landmarks except the ankle, the transmissibility decreased with increased frequency, increased amplitude or increased knee flexion angle. The transmissibility was similar between the paretic and non-paretic side, except at the ankle during tip-toe standing. Less severe lower limb motor impairment was associated with greater transmissibility at the paretic ankle, knee and hip in certain WBV conditions. Leg muscle spasticity was not significantly related to WBV transmissibility. In clinical practice, WBV amplitude, frequency, body postures need to be considered regarding the therapeutic purpose. Good contact between the feet and vibration platform and symmetrical body-weight distribution pattern should be ensured.     

The role of hind limb flexor muscles during swimming in the toad, Bufo marinus

Most work examining muscle function during anuran locomotion has focused largely on the roles of major hind limb extensors during jumping and swimming. Nevertheless, the recovery phase of anuran locomotion likely plays a critical role in locomotor performance, especially in the aquatic environment, where flexing limbs can increase drag on the swimming animal. In this study, I use kinematic and electromyographic analyses to explore the roles of four anatomical flexor muscles in the hind limb of Bufo marinus during swimming: m. iliacus externus, a hip flexor; mm. iliofibularis and semitendinosus, knee flexors; and m. tibialis anticus longus, an ankle flexor. Two general questions are addressed: (1) What role, if any, do these flexors play during limb extension? and (2) How do limb flexors control limb flexion? Musculus iliacus externus exhibits a large burst of EMG activity early in limb extension and shows low levels of activity during recovery. Both m. iliofibularis and m. semitendinosus are biphasically active, with relatively short but intense bursts during limb extension followed by longer and typically weaker secondary bursts during recovery. Musculus tibialis anticus longus becomes active mid way through recovery and remains active through the start of extension in the next stroke. In conclusion, flexors at all three joints exhibit some activity during limb extension, indicating that they play a role in mediating limb movements during propulsion. Further, recovery is controlled by a complex pattern of flexor activation timing, but muscle intensities are generally lower, suggesting relatively low force requirements during this phase of swimming.     

Force control of quadriceps muscle is bilaterally impaired in subacute stroke

We tested the hypothesis that force variability and error during maintenance of submaximal isometric knee extension are greater in subacute stroke patients than in controls and are related to motor impairments. Contralesional (more-affected) and ipsilesional (less-affected) legs of 33 stroke patients with sufficiently high motor abilities (62 ± 13 yr, 16 ± 2 days postinjury) and the dominant leg of 20 controls (62 ± 10 yr) were tested in sitting position. After peak knee extension torque [maximum voluntary contraction (MVC)] was established, subjects maintained 10, 20, 30, and 50% of MVC as steady and accurate as possible for 10 s by matching voluntary force to the target level displayed on a monitor. Coefficient of variation (CV) and root-mean-square error (RMSE) were used to quantify force variability and error, respectively. The MVC was significantly smaller in the more-affected than less-affected leg, and both were significantly lower than in controls. The CV was significantly larger in the more-affected than less-affected leg at 20 and 50% MVC, whereas both were significantly larger compared with controls across all force levels. Both more-affected and less-affected legs of patients showed significantly greater RMSE than controls at 30 and 50% MVC. The CV and RMSE were not related to the Fugl-Meyer motor score or to the Rivermead Mobility Index. The CV negatively correlated with MVC in controls but only in the less-affected leg of patients. It is concluded that isometric knee extension strength and force control are bilaterally impaired soon after stroke but more so in the more-affected leg. Future studies should examine possible mechanisms and the evolution of these changes.     

Sensory retraining improves light touch threshold of the paretic hand in chronic stroke survivors: a single-subject A-B design

Abstract

Background: Light touch, one of the primary and basic sensations, is often neglected in sensory retraining programmes for stroke survivors.

Objective: This study aimed to investigate the effects of sensory retraining on the light touch threshold of the hand, dexterity and upper limb motor function of chronic stroke survivors.

Methods: Five chronic stroke survivors with sensory impairment participated in this single-subject A-B design study. In baseline (A) phase, they only received standard rehabilitation. In the treatment (B) phase, they received a 6-week sensory retraining intervention in addition to standard rehabilitation. In both phases, they were evaluated every 3 days. Light touch threshold, manual dexterity and upper limb motor function were assessed using Semmes-Weinstein Monofilaments, Box-Block Test and Fugl-Meyer Assessment, respectively. Visual analysis, nonparametric Mann-Whitney U test and, c-statistic were used for assessing the changes between phases.

Results: All participants indicated changes in trend or slope of the total score of light touch or both between the two phases. The results of the c-statistic also showed the statistical difference in the total score of light touch between baseline and treatment in all participants (p?<?0.001). Also, the results of the c-statistic and Mann-Whitney U test supported the difference of manual dexterity and motor function of the upper limb between baseline and treatment in all participants (p?<?0.001).

Conclusion: Current findings showed that sensory retraining may be an effective adjunctive intervention for improving the light touch threshold of the hand, dexterity and upper limb motor function in chronic stroke survivors.     

低频重复经颅磁刺激联合Bobath疗法对脑卒中偏瘫患者神经功能、运动功能及平衡能力的影响

摘要 目的：观察Bobath疗法联合低频重复经颅磁刺激对脑卒中偏瘫患者运动功能、神经功能、平衡能力的影响。方法：研究对象为我院2020年05月-2022年05月期间收治的脑卒中偏瘫患者148例。按照随机数字表法分为对照组（Bobath疗法,74例）和研究组（低频重复经颅磁刺激联合Bobath疗法,74例）。观察两组平衡能力[Berg平衡量表（BBS）]、神经功能[美国国立卫生研究院卒中量表（NIHSS）]、日常生活自理能力[改良Barthel指数（mBI）]、运动功能[Fugl-Meyer上肢运动功能评定量表（FMA-UE）、Fugl-Meyer下肢运动功能评定量表（FMA-LE）]、凝血功能[凝血酶原时间（PT）、纤维蛋白原（FIB）、D- 二聚体（D-D）、活化部分凝血活酶时间（APTT）]的变化情况。结果：两组治疗20 d后NIHSS评分下降, mBI评分升高,且研究组变化程度大于对照组（P<0.05）。两组治疗20 d后FMA-UE、FMA-LE评分升高,且研究组高于对照组（P<0.05）。两组治疗20 d后BBS评分升高,且研究组高于对照组（P<0.05）。两组治疗20 d后FIB、APTT、D-D、PT均下降,且研究组低于对照组（P<0.05）。结论：低频重复经颅磁刺激联合Bobath疗法用于脑卒中偏瘫患者,可改善其凝血功能,恢复神经功能,进而改善运动功能,提高其日常生活活动能力。     

Resultant lower extremity joint moments in below-knee amputees during running stance

Resultant flexion/extension lower extremity joint moments of four below-knee amputees running between 2.5 and 5.7 m s-1 were computed during stance on their intact and prosthetic limbs. All subjects wore patellar tendon-bearing prostheses with either a SACH or Greissinger foot component. During stance on the prosthesis, the resultant hip extensor moment on the amputated side was greater in magnitude and duration than its counterpart on the intact limb during its corresponding stance period. Since the artificial foot was planted on the ground, such a moment may help control knee flexion and promote knee extension of the residual limb. For the three subjects whose knees continued to flex at the beginning of stance, there was a dominant extensor moment about the knee joint during stance on the prosthesis. By contrast, for the fourth subject whose knee remained straight or hyperextended throughout stance on the prosthesis, a flexor moment was dominant.     

Voluntary and electrically evoked strength characteristics of obese and nonobese preadolescent boys

Overweight and obese children demonstrate inferior motor performance for strength- and power-related activities requiring support or lifting of body weight. Our purpose here was to determine whether the inferior performance could be attributed to a lower strength to muscle area ratio in the obese. Eleven nonobese (16.6% fat) and 13 obese (35.5% fat) boys (9-13 years old) volunteered for the study. Peak torque was measured during voluntary isometric and isokinetic elbow flexion and knee extension at four joint angles and four velocities, respectively. The contractile properties, twitch torque, time to peak torque, and half-relaxation time were evoked for the elbow flexors by percutaneous stimulation. Elbow flexor and knee extensor cross-sectional areas (CSA) were determined by computed axial tomography taken at the mid-upper arm and mid-thigh, respectively. Isometric and isokinetic elbow flexion and knee extension strength normalized for body weight were significantly (p less than 0.05) higher in the nonobese compared to the obese boys. There were no significant (p greater than 0.05) differences, however, between groups for elbow flexor and knee extensor CSA or for absolute and relative (normalized for muscle CSA or the product of muscle CSA and height, the latter accounting for differences in moment arm length) isometric, isokinetic, or evoked twitch torque for elbow flexion or knee extension. Likewise, there were no differences between groups for the time-related contractile properties, time to peak torque, or half-relaxation time. These findings suggest that there is no difference in the intrinsic strength or contractile properties of the elbow flexor and knee extensor muscles between obese and nonobese pre-adolescent boys and that other factors, such as the handicapping effect of excess fat mass, probably account for the reduced motor performance of the obese child.