- Studies on how hormonal contraceptives affect resistance training adaptations in women have shown conflicting results, with studies reporting positive, negative, and neutral outcomes.
- A new systematic review and meta-analysis pooled all presently published studies and found that hormonal contraceptives did not affect muscle hypertrophy, strength, and power gains from resistance training in women.
- The meta-analysis included eight studies with a total of 325 participants, and the mean study length was twelve weeks. All hormonal contraceptives included in the study were oral contraceptive pills.
Do oral contraceptives affect your muscle growth, power, or strength gains from resistance training?
It doesn’t seem so.
At least not based on the new systematic review and meta-analysis published by Nolan et al.1
There’s been some confusion regarding how hormonal contraceptives such as the pill affect strength training adaptations in women, and it didn’t get less confusing when studies started reporting outcomes pointing in different directions.
This is where meta-analyses shine.
A meta-analysis is basically when you pool all similar studies in order to be better able to draw conclusions about where the evidence is pointing.
This can be especially useful to combat “type II”-errors in research, where there is an actual effect, but it is too small to reach statistical significance with the small study groups and short time-frames we usually see within the strength and conditioning field.
A good example is the research on protein requirements for muscle growth. If I recall correctly, around 80% of studies comparing a high protein intake with a low or moderate protein intake fail to see any beneficial effect on muscle growth and strength.
No Effect From Oral Contraceptive Pills On Strength, Power, or Muscle Growth
Currently, there have been eight studies published where women follow a strength training program and either use or do not use hormonal contraceptives (all oral pills).
- The training studies included in this meta-analysis lasted between 8 and 16 weeks, with a mean duration of 12 weeks and a mean number of 3.3 workouts per week.
- The participants were between 18 and 40 years of age, with a mean age of 24 years.
- They were either on oral contraceptive pills or naturally menstruating.
When Nolan et al. pooled the results of these eight studies together, they didn’t see any significant effect or even meaningful trend of hormonal contraceptives on either muscle growth, strength, or power gains.
It seems that if you are a menstruating female athlete (or a coach to one), you can look at other factors when deciding whether or not to use oral contraceptives.
You don’t need to worry about the pills sabotaging your gains.
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- The Effect of Hormonal Contraceptive Use on Skeletal Muscle Hypertrophy, Power and Strength Adaptations to Resistance Exercise Training: A Systematic Review and Multilevel Meta-analysis. Sports Med. 2023 Sep 27.
- A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018 Mar;52(6):376-384.