Variability and distribution of muscle strength and its determinants in humans.

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 (r(2)  =0.56) was weaker than that between PCSA and fascicle force (r(2)  =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. Muscle Nerve 49: 879-886, 2014.
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