Maximum voluntary isometric contraction: reference values and clinical application.

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.