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Second-Generation Oral Contraceptive Use Is Associated With Greater Muscle Hypertrophy Following Resistance Training.

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Second-generation oral contraceptive (OC) users showed greater muscle growth in specific arm and leg muscles after 12 weeks of resistance training compared to non-users. However, strength gains were similar between groups.

Keywords:
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Area of Science:

  • Exercise physiology
  • Endocrinology
  • Sports science

Background:

  • Oral contraceptives (OCs) are widely used by women of reproductive age.
  • The impact of OCs on skeletal muscle adaptation to resistance training remains incompletely understood.
  • Investigating hormonal influences on muscle hypertrophy is crucial for optimizing training protocols.

Purpose of the Study:

  • To compare muscle hypertrophy in second-generation oral contraceptive (OC) users versus non-users following a structured resistance training program.
  • To assess differences in lean tissue mass and muscle-specific growth between the two groups.
  • To evaluate potential variations in strength development.

Main Methods:

  • A 12-week resistance training intervention was conducted.
  • Participants included young, untrained women: 14 OC users and 12 eumenorrheic non-users (NOC).
  • Muscle thickness (ultrasound), body composition (DXA), and maximal joint torque were measured pre- and post-intervention.

Main Results:

  • OC users exhibited significantly greater increases in arm lean tissue mass (10.5% vs. 6.6%).
  • Hypertrophic gains were more pronounced in three specific muscle groups for OC users (4.5%-7.9% vs. 1.5%-3.1%).
  • No significant differences in maximal strength gains were observed between OC users and non-users.

Conclusions:

  • Second-generation OC use is associated with enhanced muscle hypertrophy in specific muscle groups and greater arm lean tissue accretion during resistance training.
  • The findings suggest hormonal factors related to OC use may influence muscle growth independent of strength development.
  • Further research is needed to elucidate the underlying physiological mechanisms driving these differential muscle adaptations.