Variability and distribution of muscle strength and its determinants in humans

Stebbings, Georgina K., Morse, Christopher I., Williams, Alun G. and Day, Stephen H. (2014) Variability and distribution of muscle strength and its determinants in humans. Muscle & nerve, 49 (6). pp. 879-886. ISSN 0148-639X

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Abstract

Introduction: Inter-individual variability in measurements of muscle strength and its determinants was identified to: (1) produce a normative data set describing the normal range and (2) determine whether some measurements are more informative than others when evaluating inter-individual differences. Methods: Functional and morphological characteristics of the vastus lateralis were measured in 73 healthy, untrained adult men. Results: Inter-individual variability (coefficient of variation) was greater for isometric maximal voluntary contraction (MVC) torque (18.9%) compared with fascicle force (14.6%; P = 0.025) and physiological cross-sectional area (PCSA; 17.2%) compared with anatomical cross-sectional area (ACSA, 13.0%; P < 0.0005). The relationship between ACSA and isometric MVC torque (r2 = 0.56) was weaker than that between PCSA and fascicle force (r2 = 0.68). Conclusions: These results provide a normative data set on inter-individual variability in a variety of muscle strength-related measurements and illustrate the benefit of using more stringent measures of muscle properties.