ContextWomen show an accelerated loss of muscle mass around menopause, possibly related to the decline in estrogen. Furthermore, the anabolic response to resistance exercise seems to be hampered in postmenopausal women.ObjectiveWe aimed to test the hypothesis that transdermal estrogen therapy (ET) amplifies the skeletal muscle response to resistance training in early postmenopausal women.DesignA double-blinded randomized controlled study.SettingDepartment of Public Health, Aarhus University, Denmark.ParticipantsThirty-one healthy, untrained postmenopausal women no more than 5 years past menopause.Intervention(s)Supervised resistance training with placebo (PLC, n = 16) or transdermal ET (n = 15) for 12 weeks.Main Outcome Measure(s)The primary outcome parameter was a cross-sectional area of quadriceps femoris measured by magnetic resonance imaging, and secondary parameters were fat-free mass (dual-energy X-ray absorptiometry), muscle strength, and functional tests.ResultsThe increase in muscle cross-sectional area was significantly greater in the ET group (7.9%) compared with the PLC group (3.9%) (p < 0.05). Similarly, the increase in whole-body fat-free mass was greater in the ET group (5.5%) than in the PLC group (2.9%) (p < 0.05). Handgrip strength increased in ET (p < 0.05) but did not change in the PLC group. Muscle strength parameters, jumping height, and finger strength were all improved after the training period with no difference between groups.ConclusionThe use of transdermal ET enhanced the increase in muscle mass in response to 12 weeks of progressive resistance training in early postmenopausal women.

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Influence of second generation oral contraceptive use on adaptations to resistance training in young untrained women. J Strength Cond Res 36(7): 1801-1809, 2022-The study purpose was to determine effects of using second generation oral contraceptives (OC) on muscle adaptations to resistance training in young untrained women. Twenty users and 18 nonusers of OC completed a 10-week supervised progressive resistance training program. Before and after the intervention, muscle cross-sectional area (mCSA) of the quadriceps was measured using magnetic resonance imaging and muscle fiber CSA (fCSA) was determined by immunohistochemistry. In addition, body composition (DXA, fat mass/fat-free mass), maximal isometric muscle strength (dynamometry), 5 repetition maximum (5RM) leg press strength, counter movement jump (CMJ) height, and average power using a modified Wingate test were determined. Serum hormone analysis ensured OC compliance and 4-day food records documented dietary intake. After the training period, quadriceps mCSA (OC: 11.0 6 6.0% vs. non-OC: 9.2 6 5.0%, p 5 0.001), type II fCSA (OC: 19.9 6 7.9% vs. non-OC: 16.6 6 7.2%, p 5 0.05), muscle strength (knee extension, knee flexion and 5RM, p , 0.001), and functional power (CMJ, AP, p , 0.001) were significantly increased with no significant difference between the groups. However, a tendency toward a greater increase in fat-free mass (FFM) in the OC group was observed (OC: 3.7 6 3.8% vs. non-OC: 2.7 6 3.5%, p 5 0.08). Collectively, use of second generation OCs in young untrained women did not significantly improve adaptations to 10 weeks of resistance training compared with nonusers. The trend toward greater gains in FFM in the OC group warrant future studies.

Objective: to determine whether skeletal muscle molecular markers and SC number were influenced differently in users and non-users of oral contraceptives (OCs) following 10 weeks of resistance training Methods: Thirty-eight young healthy untrained users (n=20) and non-users of OC (n=18) completed a 10-week supervised progressive resistance training program. Before and after the intervention a muscle tissue sample was obtained from the vastus lateralis muscle for analysis of muscle fiber cross sectional area (fCSA), and satellite cell (SC) and myonuclei number using immunohistochemistry, gene expression using PCR, protein expression and myosin heavy chain composition. Results: Following the training period quadriceps fCSA (p<0.05), SCs/ type I fiber (p=0.05) and MURF-1 mRNA (p<0.01) were significantly increased with no difference between the groups. However, SCs/total fiber and SCs/type II fiber increased in OC users only, and SCs/ type II fCSA tended (p=0.055) to be greater in the OC-users. Furthermore, in OC users there were a fiber type shift from MHC IIx to MHC IIa (p<0.01) and expression of MRF4 mRNA (p<0.001) was significantly greater than in non-OC users. Conclusion: Use of 2nd generation OCs in young untrained women increased skeletal muscle MRF4 expression and SC number following 10 weeks of resistance training compared to non-users.