Hormonal Contraceptives and Training: What the Evidence Actually Shows
Table of Contents
Key Takeaways: Hormonal Contraceptives and Training
- Combined oral contraceptives do not appear to meaningfully impair strength, hypertrophy, power, or anaerobic performance at the group level.
- Overall exercise performance may be slightly lower on average in OCP users, but the effect appears too small to have clear practical significance for most athletes.
- Current evidence does not support avoiding OCPs to improve performance or timing hard training around the pill cycle.
- Possible ACL protection remains uncertain. The evidence is low quality, inconsistent, and not strong enough to justify prescribing an OCP for injury prevention.
- Bone effects may differ according to menstrual status, but OCP use does not replace investigation and treatment of the underlying cause of oligo/amenorrhoea.
- Small changes in thermoregulation have been observed during active pill use, but they have not been shown to require different hydration, cooling, or training strategies.
- Athletic status alone is not a reason to recommend or avoid a combined OCP. Clinical indication, preferences, contraindications, tolerability, and individual response remain more important.
- Most of the available evidence concerns combined oral contraceptives and should not automatically be applied to hormonal IUDs, implants, injections, vaginal rings, or progestin-only pills.
Introduction: Hormonal Contraceptives and Training
Roughly 40–51% of female athletes use hormonal contraceptives, most commonly the combined oral contraceptive pill (OCP) [1]. These medications are prescribed for many reasons, including contraception, menstrual pain, and acne, and they are often regarded as relatively routine treatments. In clinical practice, I find that their wider physiological effects are not always considered in much detail once the immediate reason for prescribing has been addressed.
Hormonal contraceptives influence multiple systems throughout the body, yet their potential relevance to training is easy to overlook. Athletes and coaches are often left uncertain about whether they affect strength gains, aerobic capacity, injury risk, bone health, or recovery. The answer is less dramatic than either “the pill helps” or “the pill hurts,” and considerably more dependent on the outcome being studied, the formulation used, and the individual athlete.
That is why I wrote this article: to separate plausible physiological effects from findings that are actually useful in practice. One scope note is important from the outset. Almost all of the research discussed below concerns the combined oral contraceptive pill specifically. Evidence on IUDs, implants, injectable contraceptives, the vaginal ring, and progestin-only pills is much thinner, and the findings should not automatically be assumed to apply to those methods.
Hormonal Contraceptives and The Hormonal Environment
Combined OCPs chronically downregulate the hypothalamic-pituitary-ovarian axis and reduce endogenous oestradiol and progesteroneconcentrations while providing exogenous oestrogenic and progestin components. Hormone doses vary between formulations, which may be monophasic, biphasic, or triphasic. This is potentially relevant to training adaptation because oestrogen may influence processes involved in muscular adaptation, including protein turnover, myosin function, and satellite cell activity [2].
From a clinical perspective, this distinction also helps explain why findings from studies on combined oral contraceptives should not automatically be extrapolated to every hormonal contraceptive. In practice, combined OCPs are often the first hormonal method used by younger women, whether the primary indication is contraception, menstrual symptoms, or acne. Later, some women choose a hormonal intrauterine device instead. Although hormonal IUDs can still have systemic effects, their hormonal exposure is more locally concentrated and ovarian function is often less extensively suppressed than with combined OCPs. When discussing training adaptations or athletic performance, it is therefore important to know not just whether an athlete uses hormonal contraception, but which method she uses.
Strength, Hypertrophy, and Power: Hormonal Contraceptives and Training Adaptation
The most rigorous data on hormonal contraceptives and training comes from a 2023 systematic review and multilevel meta-analysis pooling 8 studies, 54 effects, and 325 participants who directly compared OCP users and non-users completing matched resistance-training programmes [2]. The result was about as neutral as a meta-analysis gets: OCP use had no statistically significant effect on hypertrophy, power, or strength adaptations compared with naturally cycling non-users. The standardized mean change differences were close to zero across the board, and the authors concluded there is no evidence-based rationale to advocate for or against OCP use in women doing resistance training for these goals.
Two individual findings inside that meta-analysis are worth knowing, because they explain why the “no effect” headline can feel wrong to athletes who’ve had a bad experience on the pill:
- One included trial found that OCP use was associated with smaller gains in lean mass after resistance training, whereas another reported a significantly greater increase in type I muscle fibre area among OCP users, together with a non-significant trend toward greater muscle mass gains [2].
- A broader systematic review covering 61 studies on hormonal contraceptives and both injury and performance reached a similar strength conclusion, with one caveat: one study included in that review found a contraceptive containing an antiandrogenic progestin component (such as cyproterone acetate) was associated with smaller strength gains than a non-antiandrogenic oestrogen-progestin formulation [3]. That finding rests substantially on this one key comparison study rather than a broad base of independent replications, so treat it as a real signal worth checking, not an established rule.
The possible role of progestin androgenicity is clinically interesting, but the evidence is currently too limited to make it a major basis for contraceptive selection or a routine explanation for stalled progress.
At present, there is no widely established clinical guideline that recommends a separate approach to combined OCP use solely because a woman is an athlete. In practice, the decision is still based on the same clinical considerations as it would be for other patients: the indication for treatment, the woman’s preferences, possible contraindications, expected benefits, and potential adverse effects. Common indications include contraception, menstrual symptom management, and acne.
From a clinical perspective, athletic status alone is therefore not usually a reason either to recommend or avoid an OCP. It may still be relevant to the discussion, particularly if the athlete reports changes in symptoms, training tolerance, or performance after starting or changing a formulation. However, those concerns are best considered as part of the individual clinical picture rather than as a separate prescribing rule for athletes.
Aerobic and Anaerobic Performance: Hormonal Contraceptives and Training
The largest and most methodologically careful review on hormonal contraceptives and training performance in general (not just resistance training) pooled 42 studies and 590 participants, using a Bayesian meta-analytic framework to compare OCP users with naturally menstruating women across both between-group and within-group designs [1]. The overall conclusion: OCP use is associated with a slightly inferior average exercise performance compared with non-use, but the effect is trivial in practical terms, and performance is essentially flat across the OCP consumption and withdrawal phases — meaning there’s no strong rationale to time hard sessions around the pill cycle the way some athletes try to time them around the natural cycle.
Two individual trials inside that review illustrate the upper bound of what OCP use can do to aerobic capacity in less favourable cases. In a randomized, double-blind, placebo-controlled trial, triphasic OCP use was associated with a mean 4.7% decrease in VO2max compared with a 1.5% improvement in the placebo group [1]. In a separate crossover study, four months of triphasic OCP use was followed by an 11% decline in peak oxygen uptake, along with a 14% decrease in time to peak exercise and an 8% reduction in peak power output during incremental cycling [1]. These are individual, small-sample findings — not the average effect, and not proof that the pill alone caused the changes — but they show that larger adverse changes have been observed in individual small studies, even though the pooled average effect is trivial.
Anaerobic capacity and short-duration power output show even less signal: the broader systematic review found no consistent net effect of hormonal contraceptive use on anaerobic performance at any point in the cycle [3].
From a clinical perspective, the average effect described here is probably too small for most athletes to notice in day-to-day training. More importantly, the available evidence does not support using this possible performance difference as a major basis for contraceptive decision-making. In practice, OCP selection is still guided primarily by the clinical indication, individual preferences, contraindications, tolerability, and other expected benefits or adverse effects.
I would therefore view the small average performance decrement more as a point of physiological interest than as a reason to avoid OCP use in an otherwise appropriate clinical situation. There is currently no established recommendation to optimise athletic performance by avoiding combined oral contraceptives. If an individual athlete reports a clear and reproducible change after starting or switching a formulation, that experience may still warrant a broader clinical review, but it should not be assumed from the group-level data alone.
Hormonal Contraceptives and Training: Ligament Laxity and ACL Injury Risk
This is the area where OCP use looks most plausibly protective, though the evidence quality is explicitly rated low. A systematic review and meta-analysis of 21 studies totaling 68,758 participants examined the menstrual cycle, contraceptives, and ACL injury risk [4]. The two largest and highest-quality studies included suggested hormonal contraceptives may be protective against ACL injury, and the review’s authors noted that recent studies have suggested oral contraceptives may offer up to a 20% reduction in injury risk [4] — but the same review explicitly concluded that the overall quality of the underlying evidence is very low, so this figure should be treated as suggestive rather than established.
The proposed mechanism centers on ACL laxity: oestrogen surges around ovulation are associated with increased anterior tibial translation and ligament laxity, and OCP use is thought to blunt that mid-cycle spike by suppressing the normal fluctuation in endogenous oestrogen [3]. Interestingly, one large retrospective database study covering 165,748 female patients found OCP use was associated with 18% lower odds of undergoing ACL reconstruction overall, with the association strongest in 15–19 year olds, who had 63% lower odds of ACL reconstruction while on OCPs. A separate, smaller case-control study found a different pattern: 25–29 and 30–34 year-old women undergoing ACL reconstruction were more likely to have been using OCPs than matched controls, suggesting the age-related picture is not uniformly protective [3]. That age-dependence is a detail worth knowing — these conflicting age-stratified findings caution against assuming any protective association is uniform across age groups, let alone extrapolating “OCPs protect the ACL” across an entire athletic population.
From a clinical perspective, this remains more of an interesting physiological and epidemiological signal than a basis for treatment. The association is inconsistent, the underlying evidence is low quality, and the available studies do not establish that prescribing an OCP prevents ACL injury.
I would therefore not view possible ACL protection as a reason to start, continue, or change hormonal contraception in an athlete. Contraceptive decisions are better guided by the actual clinical indication, the athlete’s preferences, contraindications, and tolerability. The injury-risk data may be worth knowing, but it does not justify hormonally manipulating an athlete solely in the hope of reducing an uncertain risk.
Hormonal Contraceptives and Training: Bone Health and Stress Fracture Risk
Bone is the area where OCP effects diverge most sharply depending on the athlete’s baseline menstrual status. A two-year randomized controlled trial in 150 competitive female distance runners found that simply randomizing eumenorrheic or oligo/amenorrheic runners to OCP use had no effect on bone mineral density or bone mineral content in the intention-to-treat analysis [5]. However, a secondary analysis restricted to runners who actually took the OCP as prescribed found that oligo/amenorrheic runners who used it gained about 1% per year in spine bone mineral density and whole-body bone mineral content — an amount comparable to runners whose periods returned on their own, and significantly greater than runners who remained oligo/amenorrheic without treatment [5]. That second finding comes from an adherence-based subgroup rather than the randomized comparison itself, so it’s suggestive rather than conclusive — women who stick with a prescribed OCP may differ from those who don’t in ways beyond the pill itself.
In other words: in this trial of competitive female distance runners, OCP assignment did not improve bone outcomes in the overall intention-to-treat analysis, including among runners with normal menstrual function — though a single trial in one athlete population doesn’t settle the question for eumenorrheic athletes generally. For athletes with oligo/amenorrhoea — which has several potential causes, including low energy availability — OCP use may offer a modest bone benefit in adherent users, though this doesn’t substitute for identifying and correcting whatever is actually causing the menstrual irregularity.
From a clinical perspective, the idea that sex hormones influence bone health is not surprising. Outside the athletic setting, hormone therapy is sometimes considered as part of osteoporosis prevention or treatment in selected postmenopausal women. That, however, is a very different physiological and clinical situation from prescribing a combined oral contraceptive to a young athlete. I therefore see these findings primarily as evidence that bone metabolism is hormonally responsive, rather than as support for using OCPs to improve bone health in otherwise healthy athletes. When menstrual irregularity is present, identifying and addressing the underlying cause remains the more important clinical question.
Hormonal Contraceptives and Training: Thermoregulation
Active OCP use may modestly shift thermoregulatory responses during exercise. In a controlled study comparing the same women during active pill use versus the hormone-free week, resting rectal temperature was 0.31°C higher during active pill-taking, remained elevated throughout an entire exercise bout, and the threshold core temperature for the onset of evaporative heat loss was 0.32°C higher during active use — alongside a 6.5 beats-per-minute higher exercise heart rate [6]. None of this was explained by differences in hydration status or inflammatory markers. The study — conducted in seven women — didn’t test perceived heat, hydration strategies, or performance in hot conditions directly, so the practical translation is necessarily cautious — but a measurably higher core-temperature threshold before heat-loss responses kick in is a plausible reason to pay closer attention to heat management in OCP users during hot-weather training or competition.
From a clinical perspective, I would treat this finding mainly as a physiological curiosity rather than something with established practical significance. The observed shifts were small, the study included only seven women, and it did not show that OCP users perform worse, overheat more easily, or require different hydration or cooling strategies.
In practice, I would not change training, competition planning, or contraceptive decisions on the basis of this study alone. It is useful for understanding that OCP use can alter thermoregulatory physiology, but the current evidence does not show that this translates into a clinically meaningful problem for most athletes.
Conclusion: Hormonal Contraceptives and Training
The current evidence does not support the idea that combined oral contraceptives either clearly improve or meaningfully impair athletic performance for most women. At the group level, strength, hypertrophy, power, and anaerobic performance appear largely unaffected, while the small average reduction observed in overall exercise performance is probably too minor to influence day-to-day training or clinical decision-making.
Some findings remain physiologically interesting. OCP use may alter hormone exposure, ligament laxity, bone metabolism, and thermoregulatory responses, but these effects do not automatically translate into useful treatment recommendations. The possible reduction in ACL injury risk is based on low-quality and inconsistent evidence, the suggested bone benefit comes mainly from a secondary analysis in oligo/amenorrhoeic runners, and the observed thermoregulatory changes have not been shown to impair performance or require different hydration or cooling strategies.
From a clinical perspective, athletic status alone is not a reason to recommend or avoid a combined OCP. The decision is still better guided by the actual indication, the athlete’s preferences, contraindications, tolerability, and the broader clinical context. I would not prescribe an OCP to improve performance, protect the ACL, or enhance bone health in an otherwise healthy athlete. Equally, I would not recommend avoiding an otherwise appropriate OCP solely because of concerns about training adaptation.
The most useful approach is therefore an individual one. If an athlete notices a clear and reproducible change in symptoms, training tolerance, or performance after starting or switching a formulation, that experience may warrant a broader clinical review. For most athletes, however, the available evidence suggests that combined OCP use is more relevant as a clinical and personal contraceptive decision than as a tool for optimising performance.
References
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7497464/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10798924/
- https://www.jscimedcentral.com/jounal-article-info/Annals-of-Sports-Medicine-and-Research/Effects-of-Hormonal-Contraceptives-on-Non-Bone-Related-Injury-Risk-and-Athletic-Performance-in-Female-Athletes:-A-Systematic-Review-of-the-Literature-5083
- https://pubmed.ncbi.nlm.nih.gov/28795075/
- https://pubmed.ncbi.nlm.nih.gov/17805075/
- https://link.springer.com/article/10.1007/s004210050123
