Sample size considerations in human muscle architecture studies

This report is a meta-analysis of the human muscle architecture literature that analyzes the number of muscles, number of subjects, and muscle fiber length coefficient of variation (CV) by body region. Methods: Muscle fiber length data are used to make recommendations for dissection-based architectural study sample sizes. Results: An average of 9 ± 10 (mean ± SD) muscles and an average of 9 ± 5 subjects were reported in the 26 studies considered. Across all studies, average fiber length CV was highly variable (18% ± 5%). This shows that sample sizes required to achieve adequate power varies by anatomical region. Conclusions: Studies involving muscle architecture should consider regional variability and effect size and determine sample size accordingly.