EFFECTS OF ACUTE CHANGES IN ESTROGEN ON MUSCLE FUNCTION OF THE FIRST DORSAL INTEROSSEUS MUSCLE IN HUMANS

1. To investigate the effect of the female reproductive hormones on mu scle function, patients undergoing in, vitro fertilization were tested during two phases of treatment. The first was following the downregul ation of pituitary gonadotrophin releasing hormone (GnRH) receptors an d the second after 9 days of gonadotrophin injections. 2. Maximal stre ngth and fatiguability of the first dorsal interosseus muscle were ass essed when oestrogen and progesterone were low and less than 2 weeks l ater when oestrogen production reached supraphysiological levels. 3. T here were no significant changes in either strength or fatigue resista nce during acute, massive fluctuations in oestrogen. These results occ urred at a time when progesterone levels remained relatively low 4. Co ntrary to previous work, the present results suggest that oestrogen do es not affect muscle strength.