Mechanisms of Estrogen Influence on Skeletal Muscle: Mass, Regeneration, and Mitochondrial Function.

Human menopause is widely associated with impaired skeletal muscle quality and significant metabolic dysfunction. These observations pose significant challenges to the quality of life and mobility of the aging population, and are of relevance when considering the significantly greater losses in muscle mass and force-generating capacity of muscle from post-menopausal females relative to age-matched males. In this regard, the influence of estrogen on skeletal muscle has become evident across human, animal, and cell-based studies.

Lack of influence of estrogen on myosin phosphorylation and post-tetanic potentiation in muscles from young adult C57BL mice.

Estrogen influences myosin phosphorylation and post-tetanic potentiation in murine fast muscle. We tested the hypothesis that this influence is mediated by estrogen effects on skeletal myosin light chain kinase (skMLCK) activity. To this end, extensor digitorum longus muscles from female wildtype and skMLCK-absent (skMLCK) mice were grouped as follows: ovariectomized with estrogen (E+), ovariectomized without estrogen (E-), sham surgery, and intact baseline.

Delay in post-ovariectomy estrogen replacement negates estrogen-induced augmentation of post-exercise muscle satellite cell proliferation.

This study examined the effects of a delay in post-ovariectomy replacement of 17β-estradiol (estrogen) on the post-exercise proliferation of muscle satellite cells. Nine-week-old, ovariectomized, female Sprague-Dawley rats (n = 64) were distributed among 8 groups based on estrogen status (0.25 mg estrogen pellet or sham), exercise status (90 min run at 17 m·min(-1) and a grade of -13.

Alternative treatments for muscle injury: massage, cryotherapy, and hyperbaric oxygen.

Current evidence suggests that popular alternative therapies such as massage, cryotherapy, and hyperbaric oxygen exposure as currently practiced on humans have little effect on recovery from minor muscle damage such as induced by exercise. While further research is still needed, hyperbaric oxygen exposure shows clear promise for potentially being a successful adjunct treatment for enhancing muscle repair and recovery from more severe crush on contusion injury in humans. Cryotherapy or icing, as currently practiced, will not likely be successful in cooling muscle sufficiently to have any significant influence on muscle repair regardless of the degree of injury.

Is intramuscular pressure a valid diagnostic criterion for chronic exertional compartment syndrome?

Objective: To compare the intramuscular pressure (IMP) of the tibialis anterior in healthy persons under several exercise conditions with the IMP diagnostic criteria in use for diagnosing chronic exertional compartment syndrome (CECS).

Data Sources: A search of MEDLINE for the period 1966 to March 2010 used the words "intramuscular," "intracompartment," "anterior compartment," and "anterior tibial compartment" linked with "pressure." Reference lists of relevant studies were searched for further articles.

The role of estrogen receptor-α in estrogen-mediated regulation of basal and exercise-induced Hsp70 and Hsp27 expression in rat soleus.

We examined the influence of estrogen receptor-alpha (ERα) activation on estrogen-mediated regulation of heat shock proteins 70 (Hsp70) and 27 (Hsp27) in soleus. Ovariectomized rats received estrogen (EST), an ERα agonist (propyl pyrazole triol, PPT), both (EST+PPT), or a sham, and they served as either unexercised controls or were subjected to exercise by having to run downhill (17 m/min, -13.5° grade) for 90 min.

Estrogen replacement and skeletal muscle: mechanisms and population health.

There is a growing body of information supporting the beneficial effects of estrogen and estrogen-based hormone therapy (HT) on maintenance and enhancement of muscle mass, strength, and connective tissue. These effects are also evident in enhanced recovery from muscle atrophy or damage and have significant implications particularly for the muscular health of postmenopausal women. Evidence suggests that HT will also help maintain or increase muscle mass, improve postatrophy muscle recovery, and enhance muscle strength in aged females.

Effect of creatine supplementation on muscle damage and repair following eccentrically-induced damage to the elbow flexor muscles.

We investigated effects of creatine (Cr) supplementation (CrS) on exercise-induced muscle damage. Untrained males and females (N = 27) ages 18-25, with no CrS history in the past 4 months, were randomly assigned to CrS (creatine and carbohydrate) (n = 9), placebo (P) (carbohydrate only) (n = 9), or control (C) (no supplements) groups (n = 9). Participants followed a 5-day Cr loading protocol of 40 g·day(-1), divided for 5 days prior to exercise, reduced to 10 g g·day(-1) for 5 days following exercise.

Effectiveness of regular proactive massage therapy for novice recreational runners.

Objectives: To assess effects of a regular massage program on novice runners over a longer-term training period.

Participants: Twelve control and sixteen massage subjects took part in the study.

Setting: Both groups participated in 10-week running preparation clinics.

Benefits of estrogen replacement for skeletal muscle mass and function in post-menopausal females: evidence from human and animal studies.

Age related loss of skeletal muscle mass and strength accelerates with the onset of menopause in women. Recent evidence from human and animal studies provides compelling evidence for the role of estrogen based hormone replacement therapy (HRT) in maintaining and enhancing muscle mass and strength and protecting against muscle damage. The physiological mechanisms by which estrogen can positively influence skeletal muscle mass and strength and protect against post-damage inflammation and disruption are also beginning to emerge.

The influence of estrogen on skeletal muscle: sex matters.

As women enter menopause, the concentration of estrogen and other female hormones declines. This hormonal decrease has been associated with a number of negative outcomes, including a greater incidence of injury as well as a delay in recovery from these injuries. Over the past two decades, our understanding of the protective effects of estrogen against various types of injury and disease states has grown immensely.

The effect of tapering period on plasma pro-inflammatory cytokine levels and performance in elite male cyclists.

The aim of this study was to investigate the effect of two different tapering period lengths on the concentration of plasma interleukin- 6 (IL-6), interleukin (IL-1β) and tumor necrosis factor-α (TNF-α) and performance in elite male cyclists. To this end, after completing 8 weeks progressive endurance exercise, twenty four high-level endurance cyclists were randomly assigned to one of two groups: a control group of cyclists (n = 12) continued performing progressive weekly training volume for 3 weeks while a taper group of cyclists (n = 12) proceeded with a 50% reduction in weekly training volume relative to the control group. A simulated 40 min time trial (40TT) performance ride was used as the criterion index of performance before and after the tapering period to evaluate the physiological and performance effects of each protocol.

Progesterone and estrogen influence postexercise leukocyte infiltration in overiectomized female rats.

Limited research has been conducted on the effects of progesterone alone, or in combination with estrogen, on leukocyte infiltration in skeletal muscle following exercise. To investigate the effects of these female sex hormones, ovariectomized female rats were divided into 4 exercise and 4 control groups: sham, estrogen, progesterone, and a combination of estrogen plus progesterone. Following 8 days of hormone replacement and 24 h postexercise, soleus (red) and superficial (white) vastus muscles were removed and immunostained for His48 (neutrophil)- and ED1 (macrophage)-positive cells.

Physiological, sensory, and functional measures in a model of wrist muscle injury and recovery.

Purpose: To evaluate the effectiveness of muscle rehabilitation modalities, it is first necessary to develop a model to test measures that would assess physiological, sensory, and functional muscle recovery. This study attempted to develop such a model for wrist injury.

Subjects: Healthy male and female adults (n = 25).

Estrogen influences satellite cell activation and proliferation following downhill running in rats.

To investigate the influence of estrogen on postexercise muscle repair processes, we examined the effects of estrogen supplementation (0.25-mg pellet) on numbers of myofibers positive for markers of total, activated, and proliferating satellite cells in rat skeletal muscles 72 h following downhill running. Ovariectomized female rats (n = 44) were divided into four groups (n = 11 per group): sham (no estrogen) controls (SC); sham, exercised (SE); estrogen-supplemented controls (EC); and estrogen-supplemented, exercised (EE).

Neutrophil infiltration in exercise-injured skeletal muscle: how do we resolve the controversy?

Neutrophils have not consistently been detected in exercise-injured skeletal muscle and, therefore, neutrophil infiltration in this muscle has become a controversial issue. Thirty-eight animal and human studies that assessed injured muscle for neutrophils and employed acute exercise (e.g.

Indices of leukocyte infiltration and muscle recovery after eccentric contraction-induced injury in young and adult male mice.

The movement of leukocytes (e.g., neutrophils and macrophages) into skeletal muscle is a critical response after a sports-related injury.

Hormone replacement and strength training positively influence balance during gait in post-menopausal females: a pilot study.

This study examined the effects of hormone replacement combined with strength training on improving dynamic balance control in post-menopausal women. Thirty one participating post-menopausal women were divided into three groups (hormone replacement (HR), non-hormone replacement (NR) and control (CR) group). HR and NR groups were tested for muscle strength and balance control during gait, prior to training and following a six week lower body strength training program.

Estrogen supplementation failed to attenuate biochemical indices of neutrophil infiltration or damage in rat skeletal muscles following ischemia.

This study examined the effects of estrogen supplementation on markers of neutrophil infiltration and damage in skeletal muscle of rats following ischemia. Male and female gonad-intact rats, with or without 14 days of estrogen supplementation were subjected to two hours of hind-limb ischemia and sacrificed at 24, 48 or 72 hours post-ischemia. Control animals were sacrificed without ischemia.

Women with fibromyalgia walk with an altered muscle synergy.

Most individuals can use different movement and muscle recruitment patterns to perform a stated task but often only one pattern is selected which optimizes an unknown global objective given the individual's neuromusculoskeletal characteristics. Patients with fibromyalgia syndrome (FS), characterized by their chronic pain, reduced physical work capacity and muscular fatigue, could exhibit a different control signature compared to asymptomatic control volunteers (CV). To test this proposal, 22 women with FS, and 11 CV, were assessed in a gait analysis laboratory.

Evaluating the influence of massage on leg strength, swelling, and pain following a half-marathon.

Massage therapy is commonly used following endurance running races with the expectation that it will enhance post-run recovery of muscle function and reduce soreness. A limited number of studies have reported little or no influence of massage therapy on post-exercise muscle recovery. However, no studies have been conducted in a field setting to assess the potential for massage to influence muscle recovery following an actual endurance running race.