Evaluating the effects of hormone therapy termination on skeletal muscle and physical independence in postmenopausal women

OBJECTIVE

In women, the age-related decline in skeletal muscle structure and function is accelerated after menopause, which implicates the role of decreased circulating estrogen levels. Indeed, boosting estrogen, by means of postmenopausal hormone therapy (HT), generally proves beneficial to skeletal muscle. The evidence regarding whether these benefits persist even after cessation of HT is limited, nor is it clear how physical behavior (PB) impacts on benefits. Hence, this exploratory study focused on the interplay between HT administration/cessation, PB and in vivo skeletal muscle structure and function.

METHODS

Fifty healthy women (≥60 y) were included; 19 had an HT administration history (≥9 mo, with now ~8-y hiatus in treatment) and 31 no such history. On seven continuous days, PB data were collected using triaxial accelerometry and analyzed using compositional data analysis. Gastrocnemius medialis muscle volume, architecture, and function were determined using ultrasonography, electromyography, dual x-ray absorptiometry, and dynamometry. Current serum estradiol levels were measured using ELISA.

RESULTS

Only fascicle length and duration of HT administration were positively associated. With respect to PB levels, we found a pattern suggesting greater vitality (higher physical activity and lower sedentarism) in previous HT users, compared with nonusers, despite the two groups currently no longer exhibiting significantly different levels of circulating estradiol.

CONCLUSIONS

After an 8-year hiatus in treatment, HT provides limited advantages in gastrocnemius medialis muscle properties. Interestingly, it perhaps enhances vitality despite prolonged cessation, which in the longer term would facilitate greater physical independence, especially considering the association of sedentary behavior with greater frailty.

Menopausal hormone therapy and change in physical activity in the Women's Health Initiative hormone therapy clinical trials

OBJECTIVE

The menopausal transition results in a progressive decrease in circulating estrogen levels. Experimental evidence in rodents has indicated that estrogen depletion leads to a reduction of energy expenditure and physical activity. It is unclear whether treatment with estrogen therapy increases physical activity level in postmenopausal women.

METHODS

A total of 27,327 postmenopausal women aged 50-79 years enrolled in the Women's Health Initiative randomized double-blind trials of menopausal hormone therapy. Self-reported leisure-time physical activity at baseline, and years 1, 3, and 6 was quantified as metabolic equivalents (MET)-h/wk. In each trial, comparison between intervention and placebo groups of changes in physical activity levels from baseline to follow-up assessment was examined using linear regression models.

RESULTS

In the CEE-alone trial, the increase in MET-h/wk was greater in the placebo group compared with the intervention group at years 3 ( P = 0.002) and 6 ( P < 0.001). Similar results were observed when analyses were restricted to women who maintained an adherence rate ≥80% during the trial or who were physically active at baseline. In the CEE + MPA trial, the primary analyses did not show significant differences between groups, but the increase of MET-h/wk was greater in the placebo group compared with the intervention group at year 3 ( P = 0.004) among women with an adherence rate ≥80%.

CONCLUSIONS

The results from this clinical trial do not support the hypothesis that estrogen treatment increases physical activity among postmenopausal women.

Influence of Estradiol Status on Physical Activity in Premenopausal Women

PURPOSE

This study aimed to determine the effects of 5 months of ovarian hormone suppression in premenopausal women on objectively measured physical activity (PA).

METHODS

Participants (age, 35 ± 8 yr; body mass index, 27 ± 6 kg·m) received monthly intramuscular injections of gonadotropin-releasing hormone agonist (GnRHAG) therapy, which suppresses pituitary gonadotropins and results in suppression of ovarian sex hormones. Women were randomized to receive concurrent transdermal E2 (GnRHAG + E2; n = 30) or placebo (GnRHAG + PL, n = 31). PA was assessed for 1 wk before and during each month of the 5-month intervention using a hip-worn accelerometer (Actical, Mini Mitter Co., Inc., Bend, OR). Estimates of time spent in sedentary, light, and moderate-to-vigorous PA (MVPA) were derived using a previously published equation. Subsets of participants in each group were also randomized to a supervised progressive resistance exercise training program.

RESULTS

Total MVPA tended toward being higher (P = 0.08) in the GnRHAG + E2 group at month 4. There were no significant effects of intervention or time in sedentary or light PA. In the subset of women who did not participate in structured exercise training for which Actical data were obtained (n = 16 in each group), total MVPA was higher at month 4 (P = 0.01).

CONCLUSIONS

PA levels seem to be maintained at a higher level in women undergoing pharmacological suppression of ovarian function with E2 add-back when compared with women treated with placebo. These data provide proof-of-concept data that E2 contributes to the regulation of PA in humans. However, given the exploratory nature of this study, future confirmatory investigations will be necessary.

Effects of ovarian hormones and estrogen receptor α on physical activity and skeletal muscle fatigue in female mice

Menopause is associated with declines in physical activity and skeletal muscle strength. Physical activity is also reduced in rodents after ovariectomy (OVX) and whole-body estrogen receptor α (ERα) knockout. However, it is unclear if the effects are estradiol (E₂) specific. Thus, the overall purpose of this study was to investigate the effects of the ovarian hormones, E₂ and progesterone (P4), and skeletal muscle ERα (skmERα) on physical activity and skeletal muscle contractility in female mice.

METHODS

Study 1: Forty female C57Bl/6J mice were given free access to running wheels for 2 weeks to assess baseline running and randomized into 4 treatment groups: OVX, OVX + E₂, OVX + P4, OVX + E₂ + P4. All mice underwent OVX, returned to wheels for 2 weeks, received hormone pellet implants and returned to running wheels for 6 weeks, after which soleus muscle contractility testing was completed. Study 2: Thirty-two skeletal muscle specific ERα knock-out (skmERαKO) mice and wildtype (WT) littermates were randomized into 4 groups: skmERαKO-Run, skmERαWT-Run, skmERαKO-Sed, and skmERαWT-Sed. Run mice were given free access to wheels for 20 wk and sedentary (Sed) mice maintained normal cage activities. At the end point, muscle contractility was tested.

RESULTS

Study 1: OVX + E₂ + P4 group ran greater distances than both the OVX and OVX + P4 groups (p ≤ 0.009). After fatiguing contractions, soleus muscles of the OVX + E₂ + P4 group maintained greater submaximal force than those of other groups (p = 0.023). Immediately after the fatiguing contractions, OVX + E₂ + P4 muscles had greater maximal force production than the OVX + E₂ group (p = 0.027). Study 2: There were no differences in running distance between skmERαWT and skmERαKO mice (p = 0.240). Soleus muscles of skmERαKO mice were more fatigable (p < 0.001) and did not recover force as well as skmERαWT mice (p < 0.001). In vivo isometric, concentric and eccentric torque was decreased in skmERαKO mice compared to skmERαWT mice (p ≤ 0.029).

CONCLUSIONS

Combined treatment of E₂ + P4 in OVX mice restored physical activity, predominantly driven by E₂, and protected soleus muscles against fatigue. Muscle of skmERαKO mice was weak regardless of physical activity. Although 20 wk of wheel running partially prevented force loss during fatigue in skmERαKO mice, force production during recovery remained low, indicating that estradiol functions through ERα in skeletal muscle.

Sex hormone effects on physical activity levels: why doesn't Jane run as much as Dick?

The relationship between physical activity levels and disease rates has become an important health-related concern in the developed world. Heart disease, certain cancers and obesity persist at epidemic rates in the US and Western Europe. Increased physical activity levels have been shown to reduce the occurrence of many chronic diseases leading to reductions in the burden on the healthcare system. Activity levels in humans are affected by many cultural and environmental factors; nevertheless, current research points to a strong biological input with potential genetic, neurological and endocrinological origins. Of unique interest, the sex hormones appear to have a very strong influence on activity levels. The current animal literature suggests that females tend to be more active than males due to biological pathways of estrogenic origin. The majority of human epidemiological and anthropological data, on the contrary, suggest women are less active than men in spite of this inherent activity-increasing mechanism. The purpose of this study is to review the current literature regarding the control of physical activity levels by the sex hormones in humans. Using the natural transitional phases of the aging endocrine system, natural periodicity of the menstrual cycle and pharmacological/hormone replacement therapy as variable experimental stages, some authors have been able to provide some information regarding the existence of an inherent activity-increasing mechanism in humans. In brief, activity levels during life stages prior to and after menopause do not significantly differ, despite the vast changes in sex hormone levels and function. Sex hormone differences throughout a regular menstrual cycle do not appear to influence activity levels in humans either; an effect that is pronounced in the female rodent. The use of hormone replacement therapies provides researchers with more systematic controls over hormone modulation in human subjects; however, this benefit comes with additional confounding variables, mostly due to disease or other states of malfunction. Despite the addition of these confounding factors, minor changes to the activity pattern have been observed in women, especially during the initial administration of the therapy. Observations are yet to be made in male subjects during replacement therapy. In general, some evidence exists suggesting that a biological mechanism extending from the sex hormones influences activity in humans. Unfortunately, despite a small number of investigative reports, the paucity of human research investigating how the sex hormones affect activity levels in humans prevents conclusive delineation of the mechanisms involved. Future research in this unique sub-field of endocrinology and exercise science utilizing more appropriate research protocols and effective techniques will provide definitive evidence of such mechanisms.

The quality of dyadic relationships, leisure activities and health among older women

We examined the combined influence of dyadic relationships and leisure activities on health. We used self-administered survey to collect data at senior centers from French and English older women (N = 257) in Montreal, Quebec. Multiple regression analyses (OLS) were used to examine the main effects of dyadic quality and leisure activities on physical and mental health. Despite controlling for specific dyadic groups, meals, and bingo, we find that the quality of dyadic relationships has a strong influence on mental health measured by spirit, happiness, and an interesting life. Leisure activities are also a significant predictor and appear to improve physical health measured by self-reported health and the number of chronic conditions. Implications for gerontology practitioners in the United States, Canada, and other Western cultures, along with research strategies, are discussed.