Author: Lau, Man-fung Dimon
Title: Effect of neuromuscular electrical stimulation on strengthening the quadriceps femoris muscles of normal subjects in the open and closed-kinetic chain positions
Degree: M.Sc.
Year: 2000
Subject: Muscles
Electric stimulation
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Department of Rehabilitation Sciences
Pages: viii, 57 leaves : col. ill. ; 30 cm
Language: English
Abstract: Objective of the Study Closed-kinetic chain position (CKC) is not commonly employed in strengthening the quadriceps femoris muscle (QFM) with neuromuscular electrical stimulation (NMES). Previous studies have not compared the effect of the positional variable and hence this study was to compare the effect of NMES on QFM of normal subjects between CKC and open-kinetic chain (OKC) positions after a 4-week's NMES training protocol. Methods Thirty normal subjects (15 male and 15 female) of age between 16 and 30 fulfilled the selection criteria were recruited and randomly assigned into the CKC, OKC and non-NMES control group. Each group contained equal number of male and female subjects. Before training, the isometric peak torque at 45o knee flexion and the isokinetic peak torque at speed of 60o /sec for knee extensors and flexors of the non-dominant leg were tested with a Cybex Norm dynamometer. During training, subjects of CKC and control group were in semi-squatting with their backs leaned against the wall behind, whilst those of OKC group were in crook-lying position. The angle of bilateral hip and knee were both at 45o. The QFM of the non-dominant leg of subjects in CKC and OKC group were stimulated at the intensity of maximal tolerable isometric contraction with a Respond Select electrical stimulator. The program of 10/50/10 was used. The duration of training was 10 minute per session, 3 sessions per week for 4 weeks. The post-test procedures were carried out within 3-4 days after the last training session. Result: The result of MANCOVA showed that there was no significant difference in the percentage change of isometric and isokinetic knee extensors and flexors among the 3 groups, and no gender factor influenced the result. When the male and female subjects were analyzed separately with MANOVA, the p-value of Wilks' Lambda between-groups approached 0.05 (p=0.073) in male subjects, whilst that in female subjects was not significant (p=.990). The male subjects in CKC group also got a significant increase in the peak torque of isokinetic knee extensors and flexors in the one-sample t-test when compared to the value=0 (p<0.0125). Post-hoc tests with Bonferroni revealed that the percentage increase in the isokinetic knee flexors in the CKC group was significantly greater than in the control group (p = 0.018) in male subjects. In female subjects, there was no significant change in all the dependent variables in the 3 groups in the above tests. Conclusion: There was no significant difference on the percentage change of the isometric and isokinetic knee extensors and flexors among the gender-mixed CKC, OKC and control group. Only male subjects had significant increase in the percentage peak torque of isokinetic extensors and flexors in the CKC group after the training protocol and have greater percentage increase in the isokinetic peak torque of knee flexors than in the control group. Despite this, CKC position is still recommended for strengthening the weak QFM with NMES in patients after ACL reconstruction because of the extra benefits of CKC positions. Further studies are suggested to recruit larger sample size, more homogenous groups, one more non-intervened control group, involve patient population, introduce endurance and functional variables and be focused on gender difference in responding to NMES.
Rights: All rights reserved
Access: restricted access

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