Objectives: The purpose of this study was to examine the prediction of skeletal muscle mass and maximum muscle strength using simplified morphology evaluation in young Japanese women from the thigh and calf perspective.

Methods: A total of 249 Japanese young women (aged 18-25 years) were used for data analyses in this study. Thigh and calf girths were measured using a tape measure at 50% of thigh length and at 30% proximal of calf length, respectively. Muscle thickness was measured using B-mode ultrasound at the anterior and posterior thigh (at 50% of thigh length) and at the posterior lower leg (at 30% proximal of calf length), respectively. The measurements were carried out on the right side of the body while the participants stood with their elbows extended and relaxed. A stepwise multiple regression analysis (method of increasing and decreasing the variables; criterion set at p < 0.05) was performed for skeletal muscle index (defined by appendicular skeletal muscle mass/height²), handgrip strength, or sit-to-stand test and five variable factors (girth (thigh and calf) and muscle thickness (anterior and posterior thigh and posterior calf)).

Results: Unlike the sit-to-stand test, skeletal muscle index or handgrip strength was correlated (p < 0.001) with the girth or muscle thickness for both thigh and calf. Unlike the sit-to-stand test, the prediction equations for skeletal muscle index and handgrip strength estimation showed significant correlations with multiple regression analysis of data obtained from the calf girth and muscle thickness. In both skeletal muscle index and handgrip strength, calf girth was adopted as a Step 1, respectively.

Conclusion: Our results indicated that skeletal muscle index and handgrip strength could be evaluated by the simplified morphology methods, especially that for the calf girth measurement, which may be a good indicator of screening/preventing for sarcopenia in healthy Japanese young women.