Effect of menstrual cycle phase on the concentration of bioavailable 17-β oestradiol and testosterone and muscle strength

Abstract

To investigate the effect of changes in sex hormone concentration on muscle strength and the bioavailability of 17-beta oestradiol (oestradiol) and testosterone, seven eumenorrheic females were tested during two phases of the menstrual cycle. Maximum voluntary isometric strength of the first dorsal interosseus muscle was measured during the early follicular and mid-luteal phases of the menstrual cycle. These phases were chosen for testing as the concentration of total oestradiol is significantly different in these two phases. Total oestradiol has been repeatedly associated with changes in muscle strength in females, whereas the effects of bioavailable oestradiol are unknown. The concentrations of total and bioavailable oestradiol and testosterone were measured in addition to the concentration of total progesterone. Concentrations of total progesterone and oestradiol were significantly different between the early follicular and mid-luteal phases of the menstrual cycle (P <0.05 and P <0.001 respectively). The concentration of total testosterone (0.7+/-0.2 and 0.8+/-0.1 nmol.l(-1) respectively) and the ratio of total oestradiol to progesterone (153.0+/-251.2 and 108.5+/-27.8 respectively) did not change significantly between the early follicular and mid-luteal phases. Bioavailable testosterone (102.2+/-66.3 and 105.0+/-90.2 pmol.l(-1) respectively) and bioavailable oestradiol (90.5+/-35.5 and 120.0+/-60.6 pmol.l(-1) respectively) did not differ significantly between phases. There were no significant differences in muscle strength during the menstrual cycle (P =0.1). Mean maximum voluntary isometric force of the first dorsal interosseus muscle did not correlate significantly with the mean concentration of any reproductive hormone measured. These results indicate that cyclical variation in endogenous reproductive hormones does not affect muscle strength.

Efeito das diferentes fases do ciclo menstrual no desempenho da força muscular em 10RM

“…Thus, the variations in the hormonal concentrations would provide better performance in the follicular phase. Nevertheless, the evidence does not support this statement (4,(8)(9)(10)17,19) . Reviewing the literature, it is observed that the issue of strength performance concerning the different phases of the MC still remains controverse (2,5,7) .…”

“…However, the literature presents controversial results (5,7) . While some evidence demonstrates there are not significant differences in physiological aspects (O 2 consumption, lactate threshold, plasmatic volume, hemoglobin concentration and ventilation) in the three phases of the MC (2) , other studies (4,(8)(9)(10) have verified differences in the hormonal concentrations, with no alteration in muscle strength between phases. Dias et al (11) assessed strength in two multiarticular resisted exercises for large muscular groups and did not find significant differences between the different phases of the MC.…”

“…Subsequently to the establishment of the inclusion criteria, 20 women volunteered to participate in the study; however, as the collections were carried out, sample loss of 55% took place and the experiment was ended with nine women. Nevertheless, it is important to highlight that the majority of studies reviewed used a reduced number of participants (4,10,11,13,17,19) . Another important limitation was the definition of the beginning and end of each phase of the MC.…”

“…Some studies have assessed the effect of the hormonal oscillations derived from the MC on physical performance (2,(4)(5)(6)(7) . However, the literature presents controversial results (5,7) .…”

The Ergogenic Effect of Elastic Therapeutic Tape on Stride and Step Length in Fatigued Runners

“…[45][46][47][48][49] If additional future data do develop to show a trend like that, then this may be seen as a limitation.…”