Maximum voluntary isometric contraction (MVIC) is a standardized method for measurement of muscle strength in patients with neuromuscular disease. Values obtained from MVIC testing are difficult to interpret at present as normative data are limited. The objective of this study was to generate reference values for MVIC. A convenience sample of 494 healthy men and women aged 20-76 years was recruited. MVIC testing was performed on nine muscle groups bilaterally: neck flexors, shoulder abductors, shoulder adductors, elbow and knee flexors and extensors, and hip and ankle flexors. MVIC was performed using the Quantitative Muscle Assessment system. Age and sex related reference values were calculated for each muscle group using quantile regression. A clinical reporting system was developed to facilitate interpretation of patient values with reference to normal percentiles. Reference values generated from this study can be used to determine the presence and extent of muscle weakness in a given population and to evaluate the effectiveness of treatment interventions.
Motor fatigue is a common complaint of polio survivors and has a negative impact on activities of daily living. The aim of this study was to establish a normative database for hand grip strength and fatigue and to investigate differences between prior-polio subjects and normal controls. Static and dynamic hand grip fatigue and maximum voluntary isometric contraction (MVIC) of hand grip were measured in subjects with a prior history of polio (n = 44) and healthy controls (n = 494). A normative database of fatigue was developed using four indices of analysis. Compared with healthy controls, subjects with prior polio had significantly reduced hand grip strength but developed greater hand grip fatigue in only one fatigue index. Quantitative measurement of fatigue in the prior-polio population may be useful in order to detect change over time and to evaluate treatment strategies.
Maximum Voluntary Isometric Contraction (MVIC) is a standardised, objective and sensitive tool for the measurement of muscle strength. The purpose of this study was to investigate different aspects of reliability of MVIC and to determine if a learning effect existed in a relatively new user of the system. Two clinical investigators participated in the study. The inter- and intra-rater reliability of MVIC of 11 muscle groups was tested on healthy subjects (n=35). Intra-class correlation co-efficients (ICCs) were calculated and the statistical methods described by Bland and Altman were applied to the data. ICCs were higher for the more experienced investigator and a learning effect was demonstrated in a relatively new user of the system. Inter-rater reliability was acceptable but lower than intra-rater reliability. Upper limb tests generally yielded higher ICCs and lower ranges of error. The ICC was similar regardless of whether the maximum or average of the two values was taken in a single session. Utilising the statistical methods proposed by Bland and Altman allows estimation of the magnitude of error of MVIC and gives additional information to the ICC. These methods may be useful in the training of investigators and in clinical interpretation of MVIC values.
Balance is essential for safe and efficient functioning in our daily lives. A decline in balance with advancing age has been demonstrated by many investigators. This article describes how the single leg stance test is effective in demonstrating this decline in asymptomatic subjects.
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