Analytical approaches to account for muscle size when evaluating strength

Skeletal muscle strength is multifactorial. Although associated, skeletal muscle size and strength often change disproportionately following resistance training with different loading paradigms. Examining strength relative to muscle size has been used to evaluate the potential contribution of muscle growth or other factors (e.g., neural or intramuscular adaptations) that occur with strength changes. Moreover, as muscle size could explain differing strength between individuals, comparisons of strength per unit of muscle size are sometimes used to account for differences in strength related to size. Several analytical approaches can be used to account for or hold muscle size fixed when evaluating strength. Based on prior work in sports medicine and other fields, we explored the use of ratio normalization and multiple regression techniques. Data from NHANES (1999-2002) and a previous investigation from our group were used in analysis demonstrations. In synthesizing and applying recommendations from previous work, we highlight some nuances and complexities with ratio normalization that may not be readily apparent without testing assumptions.