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RESEARCH PRODUCT
Muscle function in monozygotic female twin pairs discordant for hormone replacement therapy
Noorkoiv MTaija FinniPaula H. A. RonkainenKovanenSarianna SipiläMarkku AlenJaakko KaprioEija Pöllänensubject
estradiolimedicine.medical_specialtygenetic structuresPhysiology030310 physiologyMonozygotic twinStimulationplantarflexor03 medical and health sciencesCellular and Molecular NeuroscienceMuscle nerveSex hormone-binding globulinPhysiology (medical)Internal medicinemedicineHumansvoimaMuscle StrengthtwitchMuscle Skeletalväsyminen030304 developmental biology0303 health sciencesPostmenopausal womenbiologyEstradiolbusiness.industryElectromyographyEstrogen Replacement TherapySkeletal muscleTwins MonozygoticMiddle AgedestrogeeniEndocrinologymedicine.anatomical_structureTransgender hormone therapyMuscle Fatiguebiology.proteinTime to peakfatigueFemalesense organsNeurology (clinical)strengthbusinesshuman activitiesMuscle Contractiondescription
Introduction: Postmenopausal monozygotic twin pairs discordant for hormone replacement therapy (HRT) provide an advantageous study design controlling for genetic background for elucidating the relationships between aging, sex hormone levels, muscle strength, contractile capacity, and fatigability. Methods: Thirteen postmenopausal monozygotic twin pairs discordant for HRT were measured for maximal voluntary torque (MVC) and twitch characteristics using electrical stimulation before and after intermittent dynamic plantarflexor exercise until exhaustion. Results: Peak twitch torque was 32% higher in HRT users than in their non-HRT, genetically identical sisters (P = 0.002), but MVC did not differ. There were no differences in the activation level or twitch time characteristics between the co-twins. Fatigue caused decreases in MVC (P = 0.001), twitch torque (P = 0.001), time to peak (P = 0.013), and half-relaxation time (P = 0.001) similarly in HRT users and non–HRT users. Conclusion: In early postmenopausal women, involuntary but not voluntary force-generating mechanisms of the plantarflexors are augmented by the use of HRT. Muscle Nerve, 2011
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2011-01-01 | Muscle & Nerve |