To remove fat of a belly to develop muscles of arms and a breast while preventing myalgia and arthralgia among middle aged persons by limiting the moving speed in dumbbell exercising to the frequency per min. using a frequency counter and adopting the theory of arm wrestling to instruct in a dumbbell manual or the like that elbows are put on a desk or a floor to perform a stretching of the arms for a long time and long period time.

In this wood dumbbell, a frequency counter 2 is mounted on one square weight 1, a scheduled frequency per min. is set by an adjusting button 3 and when the frequency is not reached or exceed, an alarm buzzer generates a sound. According to instructions in a manual 4, cautions in application, a handling chart and the like, the muscles and joints of the arms can be protected by putting elbows on a floor, a desk or the like. A metal weight is attached to parts 5 in the adjusting of the physical weight but in principle, the total weight is set 1kg or so.