Total muscle mass "normal" and segmented muscle mass "low" do not necessarily contradict each other. The Tanita RD-545 evaluates total values and segment values with different references/scales. You can still be in the normal range as a total, while individual arms/legs are below average compared to their respective reference - or the app shows a different key figure for the total value (e.g. % of skeletal muscle mass) than for the segments (kg)