Post-menopausal women who request to begin hormone-replacement therapy (HRT) are directed to the research team. The participants are tested before beginning HRT, after two months of HRT, and five months of HRT. Tests include strength performance, central nervous system functioning, body composition, resting metabolic rate, and vascular screening. The participants are provided a 12-week training intervention (2 x strength, 2 x endurance per week) that can be voluntarily followed between tests at month 2 and 5. Compliance with the training program is recorded. A minimum of 15 participants are needed a priori, but the investigators aim to recruit and test 20 women.
Study aim: To determine cortico-reticular functioning during low and high female sex hormone, estrogen and progesterone, concentrations. Hypothesis: Greater functioning/response during neurophysiological tests will occur in the presence of high compared to low estrogen concentrations accompanying greater force production capacity. In addition, pathways reliant on a greater number of synapses, i.e. cortico-reticulospinal, will demonstrate the greatest difference between hormone concentrations. Justification: Several studies in monkeys and humans suggest that the methodology employed is sensitive to distinguish between high and low force production capacity. Estrogen is a neurotransmitter agonist exerting its influence at least via glutamate and GABA interneuron functioning, respectively. The MENSA study is a locally administered trial where volunteers who request to be put on combined hormone replacement therapy will be recruited through cooperation with gynaecologists in the Jyväskylä area. Participants visit the University of Jyväskylä laboratories 1-5 days before beginning treatment (baseline), 2 months after beginning treatment and 5 months after beginning treatment having completed a 12-week non-supervised exercise intervention. The experimental sessions will be conducted in the morning (beginning at approximately 7 am) following an overnight fast, and the time of the day kept constant for each individual participant (± 1 h). The posteriori measurement of serum follicular-stimulating hormone, estradiol and progesterone concentrations will be used to verify the hormonal status of the participants. A recent study showed that a sample of 12-15 participants would be expected to lead to moderate-to-large (0.2-0.9) effect sizes in the tests of cortico-cortico and cortico-reticular functioning. The target muscle is the biceps brachii performing voluntary unilateral isometric elbow flexion actions. MENSA aims to recruit 20 females; this attempts to overcome potential reduced sample size through drop-out or measurement/technical error, as well as sufficiency for detection of possible changes in secondary outcome measures.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
20
A 12-week, 4 x per week (2 x strength and 2 x endurance) training program to be performed voluntarily by the participants after tests at month 2.
University of Jyväskylä
Jyväskylä, Finland
RECRUITINGShort-interval intracortical inhibition (SICI)
Ten double-pulse transcranial magnetic stimulations delivered with 3 ms inter-stimulus interval. The conditioning pulse delivered at 80% of active motor threshold and the test pulse delivered at 120% of active motor threshold. Motor-evoked potential amplitude compared to single-pulse responses at 120% of active motor threshold.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Motor-evoked potential recruitment curve
Ten transcranial magentic stimulations (single-pulse) at 100%, 120%, 140%, 160%, 180% and 200% of active motor threshold. Calculations of I50 and area-under-the-recruitment-curve to be performed offline.
Time frame: Change from baseline to month 2 and change from baseline to month 5
StartleTMS
Twenty single-pulse transcranial magnetic stimulations delivered using 120% of active motor threshold. Ten stimulations without sound and ten stimulations conditioned by a loud sound (120 dB, 50 Hz) delivered 50 ms prior to TMS discharge.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Intra-cortical facilitation (ICF)
Ten double-pulse transcranial magnetic stimulations delivered with 15 ms inter-stimulus interval. The conditioning pulse delivered at 80% of active motor threshold and the test pulse delivered at 120% of active motor threshold. Motor-evoked potential amplitude compared to single-pulse responses at 120% of active motor threshold.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Long-interval intracortical inhibition (LICI)
Ten double-pulse transcranial magnetic stimulations delivered with 50 ms inter-stimulus interval. The conditioning pulse delivered at 120% of active motor threshold and the test pulse delivered at 120% of active motor threshold. Motor-evoked potential amplitude of the test pulse compared to the amplitude of the conditioning pulse.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Motor-evoked potential to anterior-posterior current
The TMS coil is rotated 180 degrees to induce the opposite direction current within the cortex. A new active motor threshold for this coil orientation is first attained and then ten stimulations with 120% and 140% of active motor threshold are delivered. Motor-evoked potential amplitude is analysed offline.
Time frame: Change from baseline to month 2 and change from baseline to month 5
StartReact
Reaction test where the participant contracts the biceps brachii upon seeing a flashing white LED light 1 m in front. Ten flashes occur without accompanying sound. Ten flashes occur accompanied by a quiet sound (80 dB, 50 Hz). Ten flashes occur accompanied by a loud sound (120 dB, 50 Hz). The order of the conditions presented is randomized and separated by approximately 8 s. Reaction time is analysed from the presentations of the flash to the beginning (7 SD above baseline) of the voluntary electromyogram burst. The difference in the reactions times between conditions are calculated. Further analyses regarding rate of force development and voluntary EMG amplitude over 0-50 ms from each contraction are assessed.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Maximum isometric voluntary contraction (MVC)
Testing is performed under controlled pre-test conditions (10-12 h fast, no vigorous physical activity in the prior 24 h), seated in a thermoneutral room. The participant performs 3-5 isometric elbow flexion actions by maximally contracting the biceps brachii muscle while seated in an electromechanical dynamometer. Force and electromyography (EMG) activity are recorded during the contractions.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Resting energy expenditure (i.e. resting metabolic rate)
Measured by Indirect Calorimetry Resting energy expenditure (REE) is measured by indirect calorimetry (ventilated hood; overnight fast 10-12 h; supine, thermoneutral room). After stabilization, VO2 and VCO2 are recorded for ≥20-30 min; a steady-state segment (e.g., ≥5 min with CV \<10% and physiologic RQ) is used to compute REE (kcal/day) via the Weir equation, higher values = higher energy expenditure. Outcome is change from baseline to follow-up (follow-up - baseline); higher positive values = higher increase in energy expenditure. Procedures/quality criteria follow the device manual and the Statistical Analysis Plan (SAP). Per SAP, supportive analyses may adjust for body composition (FFM/FM) or express REE relative to FFM; these do not replace the prespecified analysis of this primary outcome.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Total fat mass
Total fat mass (FM) will be measured by bioelectrical impedance analysis (BIA; InBody) under standardized conditions, including a 10-12 h fast before assessment. FM is reported in kg; higher values indicate higher fat mass. The outcome is the change from baseline to the specified follow-up (follow-up - baseline).
Time frame: Change from baseline to month 2 and change from baseline to month 5
Fat-free mass
Fat-free mass (FFM) will be measured by bioelectrical impedance analysis (BIA; InBody) under standardized conditions, including a 10-12 h fast before assessment. FFM is reported in kg; higher values indicate higher fat-free mass.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Aotic pulse wave velocity
Aortic pulse wave velocity (PWV) will be measured using an oscillometric Arteriograph device under standardized resting conditions, including a 10-12 h fast and avoidance of vigorous physical activity during the previous 24 h. Measurements are taken supine in a quiet, thermoneutral room. PWV is reported in m/s; higher values indicate greater arterial stiffness.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Arterial wave reflection
Augmentation Index (AIx) will be measured using the Arteriograph under the same standardized resting conditions, including a 10-12 h fast and avoidance of vigorous physical activity during the preceding 24 h. AIx is expressed in %; higher values indicate greater arterial wave reflection.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Reflection time
Reflection time measured by Arteriograph in standardized rest (as above). ms; shorter RT = faster wave return.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Microvascular perfusion
Resting cutaneous microvascular perfusion measured at the forearm using Laser Doppler under standardized resting conditions (10-12 h fast, no vigorous physical activity in prior 24 h, supine, thermoneutral). Perfusion units (PU); higher = higher resting microvascular flow.
Time frame: Change from baseline to month 2 and baseline to month 5
Endothelium-Dependent Vasodilation (Laser Doppler, %)
Endothelium-dependent vasodilatory response measured at the forearm using Laser Doppler during standardized forearm occlusion to induce a controlled ischemic stimulus under resting conditions (as above). % change from baseline; higher = better endothelial function.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Post-Occlusive Reactive Hyperemia (PORH, %)
Post-occlusive reactive hyperemia measured at the forearm with Laser Doppler under standardized rest (as above). % increase; higher = better microvascular reactivity.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Resting Near-Infrared Spectroscopy (NIRS) Tissue Oxygen Saturation (StO2, %)
Near-Infrared Spectroscopy (NIRS)-derived quadriceps StO2 at rest under standardized conditions (10-12 h fast, no vigorous PA in prior 24 h, supine, thermoneutral). %; higher = higher oxygenation.
Time frame: Change from baseline to month 2 and change from baseline to month 5
Near-Infrared Spectroscopy (NIRS) Total Hemoglobin (tHb, au)
NIRS-derived tHb signal (during rest). Arbitrary units; marker of local microvascular blood volume.
Time frame: Change from baseline to month 2 and change from baseline to month 5
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