The relationship between oestrogen and muscle strength: a current perspective

Abstract

The relationship between muscle strength and oestrogen is ambiguous and is still largely unresolved. The evidence for and against an effect of oestradiol on determinants of muscle function is equivocal and often contradictory. The bulk of the research in this area was performed during the eighties and nineties, using models of reproductive functioning such as; the menstrual cycle, the menopause and hormone replacement therapy, oral contraceptives and in vitro fertilisation treatment, to alter the female hormonal milieu. In the last decade, approximately 15 papers have demonstrated a relationship, both positive and negative, between the concentration of oestrogen and skeletal muscle strength. Conversely, around 20 articles have not shown any infl uence of oestrogen on a number of strength measures. The majority of these studies were performed using post-menopausal and eumenorrheic females. Most current studies use hormonal assays to confi rm oestrogen status, however no recent studies have reported the bioavailable concentration of oestradiol. Similarly, no research in the last 10 years has used in vitro fertilisation treatment or pregnancy as acute and chronic models of supra-physiological changes in sex hormone concentration. Future work should focus on performing meta-analyses on each of the key components of muscle strength in an attempt to elucidate a causal relationship. In addition, models of reproductive functioning that cause the greatest magnitude of change to oestrogen concentration should be used, while controlling as many confounding factors as possible.

The Variability of the Components of Fitness along the Menstrual Cycle

“…Despite the theoretical implications that the different hormonal environments (i. e. low, high-low, high-high estrogen and progesterone levels) could have on the aforementioned components of fitness, previous studies analyzing the differences between MC phases present controversial results either for fat oxidation [28], muscle strength [29] or cardiorespiratory fitness [6]. One of the potential causes of such discrepancy is the heterogeneity of hor-mone levels among eumenorrheic women and between days in each MC phase [15,16].…”

“…Eighteen physically active eumenorrheic women volunteered to participate in this study (mean ± standard deviation [SD]: age = 23.4 ± 2.7 years [range: [20][21][22][23][24][25][26][27][28][29]; body height = 1.64 ± 0.09 m; body mass = 62.7 ± 9.2 kg). One subject dropped out of the study due to a negative urine LH surge, and two subjects did not complete one of the three testing sessions.…”