Strengthening of Quadriceps by Neuromuscular Magnetic Stimulation in Healthy Subjects.

BACKGROUND: Quadriceps muscle strengthening is one of the rehabilitation strategies for improving walking in some people with gait impairments, and neuromuscular electrical stimulation (NMES) has been used for that reason. The strengthening effect of neuromuscular magnetic stimulation (NMMS) on the quadriceps has been demonstrated in various conditions, but not specifically for gait training. The purpose of this study was to determine whether the effect of NMMS is clinically applicable. OBJECTIVE: To determine the effect of NMMS on quadriceps muscle strength, cross-sectional area (CSA) and thickness in healthy subjects. DESIGN: Single-blind, prospective, case-control study. SETTING: Tertiary academic hospital setting. PARTICIPANTS: A total of 40 healthy volunteers were randomly assigned to an NMMS (n = 20) or control group (n = 20). INTERVENTIONS: Fifteen minutes of quadriceps NMMS of at maximum tolerable intensity, 3 times per week for 5 weeks. MAIN OUTCOME MEASUREMENTS: At baseline and after the intervention, the CSA and thicknesses of the rectus femoris and vastus intermedius were measured by ultrasound. Isometric and isokinetic maximal and average peak torques of the dominant side knee extensors were also measured at pre- and postintervention. RESULTS: There were no between-group differences in strength, CSA, or muscle thickness at baseline. Isometric maximum and average peak torque of NMMS group were increased significantly after 5 weeks of intervention (P < .001). The isokinetic maximum and average peak torque of NMMS group were increased significantly at both angle velocities of 60°/sec and 120°/sec after 5 weeks of intervention (P < .001). However, neither group showed a significant difference in cross-sectional area or thickness after training. CONCLUSION: NMMS can be a useful strengthening method for large skeletal muscles such as the quadriceps. LEVEL OF EVIDENCE: II.

Effect of lower limb strength on falls and balance of the elderly.

OBJECTIVE: To assess the effect of lower limb strength on falls and balance in community-dwelling elderly persons by a health status questionnaire, evaluation of lower limb strength and balance. METHOD: A total of 86 subjects (age 69.8±5.3) were categorized into one of two groups, "Fallers" and "Non-fallers". Thirty one participants who had reported the experience of having fallen unexpectedly at least once in the past year were assigned into the group "Fallers", and the remaining 55 subjects having no fall history in the past year, "Non-fallers". A self-assessment questionnaire was taken. Lower limb strength was measured by a "Chair stand test". Balance was measured by the stability index of the fall risk test protocol of Balance System SD® (Biodex, New York, USA). The differences between the two groups were compared and the correlation between lower limb strength and balance were analyzed. RESULTS: The questionnaire demonstrated no significant differences between two groups. The "Chair stand test" showed a significantly less for the "Fallers" (p<0.05). The stability index was significantly greater in the "Fallers" group (p<0.05). There was a moderate negative correlation between the "Chair stand test" and the "Stability index" (R=-0.576, p<0.01). CONCLUSION: This study suggests that the "Chair stand test" is a useful screening process for lower limb strength which correlates to risk for falls and balance in the elderly.

Spasticity and electrophysiologic changes after extracorporeal shock wave therapy on gastrocnemius.

OBJECTIVE: To evaluate the spasticity and electrophysiologic effects of applying extracorporeal shock wave therapy (ESWT) to the gastrocnemius by studying F wave and H-reflex. METHOD: Ten healthy adults and 10 hemiplegic stroke patients with ankle plantarflexor spasticity received one session of ESWT on the medial head of the gastrocnemius. The modified Ashworth scale (MAS), tibial nerve conduction, F wave, and H-reflex results were measured before and immediately after the treatment. The Visual Analogue Scale (VAS) was used during ESWT to measure the side effects, such as pain. RESULTS: There were no significant effects of ESWT on the conduction velocity, distal latency and amplitude of tibial nerve conduction, minimal latency of tibial nerve F wave, latency, or H-M ratio of H-reflex in either the healthy or stroke group. However, the MAS of plantarflexor was significantly reduced from 2.67±1.15 to 1.22±1.03 (p<0.05) after applying ESWT in the stroke group. CONCLUSION: After applying ESWT on the gastrocnemius in stroke patients, the spasticity of the ankle plantarflexor was significantly improved, with no changes of F wave or H-reflex parameters. Further studies are needed to evaluate the mechanisms of the antispastic effect of ESWT.

Motor unit number estimation and motor unit action potential analysis in carpal tunnel syndrome.

OBJECTIVE: To evaluate the clinical significance of motor unit number estimation (MUNE) and quantitative analysis of motor unit action potential (MUAP) in carpal tunnel syndrome (CTS) according to electrophysiologic severity, ultrasonographic measurement and clinical symptoms. METHOD: We evaluated 78 wrists of 45 patients, who had been diagnosed with CTS and 42 wrists of 21 healthy controls. Median nerve conduction studies, amplitude and duration of MUAP, and the MUNE of the abductor pollicis brevis were measured. The cross sectional area (CSA) of the median nerve at the pisiform and distal radioulnar joint level was determined by high resolution ultrasonography. Clinical symptom of CTS was assessed using the Boston Carpal Tunnel Questionnaire (BCTQ). RESULTS: The MUNE, the amplitude and the duration of MUAP of the CTS group were significantly different from those found in the control group. The area under the ROC curve was 0.944 for MUNE, 0.923 for MUAP amplitude and 0.953 for MUAP duration. MUNE had a negative correlation with electrophysiologic stage of CTS, amplitude and duration of MUAP, CSA at pisiform level, and the score of BCTQ. The amplitude and duration of MUAP had a positive correlation with the score of BCTQ. The electrophysiologic stage was correlated with amplitude but not with the duration of MUAP. CONCLUSION: MUNE, amplitude and duration of MUAP are useful tests for diagnosis of CTS. In addition, the MUNE serves as a good indicator of CTS severity.