Molecular markers of skeletal muscle hypertrophy following 10 wk of resistance training in oral contraceptive users and nonusers

Abstract

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.

Influence of Fermented Red Clover Extract on Skeletal Muscle in Early Postmenopausal Women: A Double-Blinded Cross-Over Study

“…The western blotting protocol followed standard procedures described in more detail in Oxfeldt et al [ 38 ]. In short, protein samples were separated using a sodium dodecyl sulfate (SDS)-polyacrylamide gel and electroblotted onto polyvinylindene difluoride (PVDF) membranes before being blocked and incubated in primary antibodies overnight.…”

Combined hormonal contraceptive use is not protective against musculoskeletal conditions or injuries: a systematic review with data from 5 million females

“…Of 5438 potential records identified from database searches, 50 were included (figure 1)34–83 incorporating data from 5 695 908 participants from 48 unique cohorts 34 35 38–66 69–83…”

“…Included studies are summarised in online supplemental file 1. Three were RCTs (6%),35 43 74 14 were quasi-experimental (28%),46 47 49 50 52 56 62 64–66 76 77 79 83 25 were prospective cohort studies (50%)38–42 44 45 48 51 53–55 57 60 61 63 69–72 75 78 80–82 and 8 were retrospective cohort studies (16%) 34 36 37 58 59 67 68 73…”

“…Six studies (12%)39 40 64 66 71 76 assessed participants who took CHC under the age of 18 (adolescent) exclusively and 44 studies (88%)34–38 41–63 65 67–70 72–75 77–83 assessed participants across various age ranges without stratification by age groups. The length of CHC interventions across studies ranged from 28 days5161 to 14.5 years 59.…”

Effects of oral contraceptive use on muscle strength, muscle thickness, and fiber size and composition in young women undergoing 12 weeks of strength training: a cohort study

“…Furthermore, Wikstrom-Frisen et al found no significant differences in strength, squat jump ability, or isokinetic peak torque between women who used OCs and those who did not [ 52 ], while Nichols et al found no differences in isokinetic torque and maximum strength gain between female student athletes who used OCs and those who did not [ 22 ]. According to Oxfeldt et al, 10 weeks of resistance training increased ‘muscle regulatory factor 4’ expression levels as well as satellite cell numbers in women who used OCs compared to nonusers [ 53 ], and Dalgaard et al reported that the use of third-generation OCs was associated with an increase in muscle mass [ 54 ]. These data indicate that OC use does not negatively influence strength and appears not to interrupt the anabolic response of muscles to resistance exercise [ 15 , 19 , 55 ].…”