Physiological Changes Accompanying Menstrual Cycle in Japanese Females

Second Report: On the Muscular Strength

Abstract

Grip strength and back strength were measured twice a day (in the morning and evening) on every other day in 10 healthy girl students (18 -19 of age). The result obtained from 60 days' measurements was as follows:
1. Individual difference was remarkable in patterns of the fluctuation in muscular strength as referred to the monthly cycle.
2. Back strength of 6 cases inclined to be reduced from several days before menstruation to intermenstrual period. Other 4 cases showed no change.
3. Grip strength was more stable than back strength. The latter is sometimes affected by the influence of pains in abdominal region during menstruation.
4. The fact that the reduction of muscular strength in the evening compared with that in the morning, was more remarkable before and during menstruation is discussed.