Menstrual Cycle & Muscle Gain: Research Debunks Myth
- New research from McMaster University kinesiologists casts doubt on the popular online claim that aligning resistance training with specific menstrual cycle phases boosts muscle and strength gains.
- Lauren Colenso-Semple, the study's lead author, stated that their findings contradict the widespread belief in a hormonal advantage from tailoring exercises to each menstrual phase.
- The researchers monitored the menstrual cycles of healthy young women for three months to confirm their regularity.
New research debunks the popular myth: Menstrual cycle timing doesn’t enhance muscle growth. This groundbreaking study, published in the Journal of Physiology, challenges the idea that adjusting resistance training to menstrual phases benefits muscle protein synthesis—a critical process for muscle gain and repair. Scientists found no significant difference in muscle protein production, irrespective of exercise timing during the follicular or luteal phases, directly contradicting the trend of cycle syncing for workouts. contrary to what you see on social media, the McMaster University research team observed no hormonal advantage from tailored exercises. This study emphasizes the need for further investigation into women’s health and exercise. News Directory 3 is keeping a close eye on advances in this field. Discover what’s next for fitness and women’s health.
Menstrual Cycle Timing Doesn’t Impact Muscle Growth, study Finds
Updated June 12, 2025
New research from McMaster University kinesiologists casts doubt on the popular online claim that aligning resistance training with specific menstrual cycle phases boosts muscle and strength gains. The study,published in the Journal of Physiology,reveals that exercising at different points in the cycle had neither a positive nor a negative effect on muscle protein synthesis,a crucial process for muscle advancement and maintenance.
Lauren Colenso-Semple, the study’s lead author, stated that their findings contradict the widespread belief in a hormonal advantage from tailoring exercises to each menstrual phase. The research team observed no important differences in muscle protein production regardless of when participants worked out during their cycles.
The researchers monitored the menstrual cycles of healthy young women for three months to confirm their regularity. Contrary to common assumptions, only about 12% of women have a consistent 28-day cycle with ovulation occurring predictably on day 14.
Participants ingested a tracer molecule to track muscle protein levels and then engaged in heavy resistance exercise during two key phases: the follicular phase, marked by peak estrogen, and the luteal phase, characterized by peak progesterone.The team found no impact from either phase on muscle protein production.
Cycle syncing,promoted by online influencers,encourages coordinating workouts,diets,and lifestyle choices with the menstrual cycle. Fitness apps and social media channels offer extensive advice on this practice. Proponents frequently enough cite animal studies suggesting ovarian hormones affect muscle response to exercise, but this new research indicates that those findings do not translate to humans.
“Our work shows that women who want to lift weights and recondition their muscles should feel free to do so in any phase of their cycle. There is no physiological difference in response to the exercise,” said Stuart Phillips, the Canada Research Chair in Skeletal Muscle Health at McMaster, who supervised the study. “It is important to tailor your training to how you feel.”
Scientists are calling for further research focused on women’s health, including the effects of training in relation to the menstrual cycle and how both oral and non-oral contraceptives influence exercise responses. This additional research will help provide a more complete picture of women’s health and fitness.
What’s next
Future studies should explore the impact of training strategies on women’s health,notably focusing on the menstrual cycle and the use of contraceptives to better understand exercise responses.