Our previous study found that one maximal voluntary eccentric contraction (MVC-ECC) performed daily for 5days a week for 4weeks increased MVC-ECC, isometric (MVC-ISO), and concentric contraction (MVC-CON) torque of the elbow flexors more than 10%. The present study investigated the effects of six maximal voluntary eccentric contractions on the MVC torques and biceps brachii and brachialis muscle thickness (MT). Thirty-six healthy young adults were placed to one of the three groups (N = 12 per group); the 6×1 group that performed one set of six contractions once a week, the 6×5 group that performed one set of six contractions a day for 5days a week, and the 30×1 group that performed five sets of six contractions a day in a week.