Menstrual Cycle & Injury Risk.

Female athletes have higher rates of some injuries in certain sports and athlete populations, including ACL injuries and bone stress injuries.

This has led to increasing interest in whether changing hormones across the menstrual cycle influence injury risk.

You may have seen claims that ovulation is a “danger zone” for ACL injuries or that female athletes should change their training depending on the week of their cycle.

The research however is far less certain. The menstrual cycle may influence the body, but we cannot currently identify a specific phase when every female athlete is at greater risk of injury.

What we do know is that menstrual health matters — particularly when irregular or absent periods are associated with under-fueling, low energy availability and poor bone health.

Oestrogen and progesterone naturally fluctuate throughout the menstrual cycle. These hormones can affect tissues including muscle, tendon and ligament, which provides a plausible reason why injury risk has been investigated.

Earlier studies suggested ACL injuries might occur more frequently around the preovulatory or ovulatory phase. A systematic review by Herzberg et al. (2017) also found small changes in knee ligament laxity across the cycle.

However, ligament laxity is not the same as sustaining an ACL injury, and much of the early research was small or methodologically weak.

A more recent systematic review found that four of seven studies showed no significant differences in ACL-related biomechanical or neuromuscular risk factors across menstrual-cycle phases. Overall, the evidence was considered low to very low quality (Dos’ Santos et al., 2023).

So, based on current evidence, we cannot confidently identify a period of time we should expect a higher incidence of injury.

The evidence is just as uncertain.

A 2026 systematic review and meta-analysis looked specifically at menstrual cycle phase and muscle injuries in female team sport athletes. Only three studies involving 318 athletes met the inclusion criteria.

Researchers found no significant difference in muscle injury risk between menstrual cycle phases (Guthardt et al., 2026).

A recent review by Hackney, Hansen and Melin (2025) similarly concluded that the effect of menstrual cycle phase on sport performance and training adaptation remains an area of debate rather than settled science.

The idea is that women should change their strength, running or high-intensity training depending on cycle phase has become popular on social media. However, the science is not strong enough to justify this.

AIS researcher Clare Minahan (2025) recently highlighted the gap between social media claims & actual evidence surrounding menstrual cycle based training. Current research does not support routinely redesigning training programs according to menstrual cycle phase.

That does not mean the menstrual cycle should be ignored. Athletes may experience significant fatigue, pain, poor sleep, heavy bleeding or other symptoms & training should be adjusted to make sure quality training can be rescheduled when the symptoms have resolved.

The key is to respond to the individual athlete, rather than assuming every woman needs the same training changes on the same cycle days.

This is perhaps the most important message. There is much stronger evidence linking menstrual dysfunction (irregular or absent cycle) to low energy availability, poor bone health & in turn, to bone stress injuries.

Low energy availability occurs when an athlete does not consume enough energy (fuel with food) to support both training and normal physiological function. The body responds to this by shutting down processes such as the menstrual cycle as it deems the body not able to sustain a normal pregnancy due to the lack of fuel.

Over time, this can contribute to Relative Energy Deficiency in Sport (REDs) and affect reproductive function, bone health, recovery, immunity and performance (Mountjoy et al., 2023).

Research involving female athletes with multiple bone stress injuries has found a higher prevalence of current or previous amenorrhoea (absent period) — compared with athletes with fewer or no bone stress injuries (Rudolph et al., 2021).

Similarly, Holtzman et al. (2022) found that accumulating RED-S or Female Athlete Triad risk factors was associated with a higher risk of bone stress injuries and poorer bone health.

This is why losing your period because you are training hard should never simply be considered a sign of being fit or a badge of honour for working hard – it deserves investigation.

** One important point – if you are taking the contraceptive pill, you are unable to track your period as the bleeding that occurs is a withdrawal bleed (from the pill that you take) – not a natural period.

Some earlier studies suggested hormonal contraception might reduce ACL injury risk. However, a large systematic review involving data from more than five million females found insufficient high-quality evidence that combined hormonal contraception protects against musculoskeletal injury (White et al., 2023).

There is another important consideration for female athletes using the combined oral contraceptive pill. The pill generally suppresses ovulation and replaces the normal hormonal fluctuations of a natural menstrual cycle with synthetic hormones.

Bleeding during the placebo or pill free days is therefore a withdrawal bleed caused by the drop in synthetic hormones — it is not a true menstrual period.

This means an athlete taking the combined pill cannot use the timing of that bleed to track her natural menstrual cycle phases or as confirmation that normal menstrual function is occurring.

This is particularly important when monitoring athlete health because hormonal contraception can mask menstrual disturbance that might otherwise provide a warning sign of low energy availability or RED-S. Athletes can still track withdrawal bleeding, symptoms and how they feel during different parts of their contraceptive regimen, but this is different from tracking a natural menstrual cycle.

The AIS Female Performance & Health Initiative specifically provides separate education on the normal menstrual cycle and contraception for female athletes, reflecting this important distinction between natural menstrual function and bleeding while using hormonal contraception.

Hormonal contraception can be useful for contraception and for managing conditions or troublesome menstrual symptoms, but the choice should be individualised with a doctor. It should not currently be prescribed simply to reduce ACL or musculoskeletal injury risk.

Rather than changing training because an app says you are approaching ovulation, there is much stronger evidence for neuromuscular injury-prevention training.

The 2025 IOC Female Athlete Injury Prevention (FAIR) review and consensus found that neuromuscular training programmes can substantially reduce ACL injuries in female athletes, with the systematic review estimating an approximately 61% reduction in ACL injury rates (Bullock et al., 2025; Crossley et al., 2025).

Importantly, this is more than simply “doing some strength work”.

Effective programmes typically combine lower-limb and core strength, balance, landing and movement control, agility, deceleration and change-of-direction training, progressing from two-leg to more demanding single-leg and sport-specific tasks.

The IOC FAIR recommendations suggest incorporating this type of neuromuscular warm-up for at least 10 minutes, twice per week.

There is also evidence that these programmes can change the way athletes move. In a small randomised trial, eight weeks of neuromuscular training improved lower-limb muscle co-activation and reduced dynamic knee valgus during a single-leg jumping task by 5.9° (Ramezani et al., 2024).

This does not prove that correcting valgus alone prevents ACL injury, but it demonstrates that important aspects of movement control are trainable.

A newer systematic review and meta-analysis also found lower ACL injury odds among female athletes completing neuromuscular training (Chen et al., 2026), adding further support to this approach.

The practical message: don’t avoid training because of a particular menstrual cycle phase. Instead, build injury prevention into normal training all year round.

A good program should include:

• strength
• balance
• single-leg control
• landing
• deceleration
• agility
• change of direction
• sport specific movements
• good coaching
• progressive difficulty

References

Australian Institute of Sport. Female Performance & Health Initiative: Information and Resources. Australian Sports Commission. Includes resources on menstrual-cycle health, menstrual tracking and hormonal contraception.

Australian Institute of Sport. Female Performance & Health Initiative: Education Modules. Includes menstrual health, hormonal contraception, bone health, low energy availability and nutrition modules.

Barrack MT, Gibbs JC, De Souza MJ, Williams NI, Nichols JF, Rauh MJ, Nattiv A. (2014). Higher incidence of bone stress injuries with increasing Female Athlete Triad-related risk factors: a prospective multisite study of exercising girls and women. American Journal of Sports Medicine, 42(4), 949–958. doi:10.1177/0363546513520295.

Bullock GS, Räisänen AM, Martin C, et al. (2025). Prevention strategies for lower extremity injury: a systematic review and meta-analyses for the Female, woman and/or girl Athlete Injury pRevention (FAIR) consensus. British Journal of Sports Medicine, 59(22), 1575–1586. doi:10.1136/bjsports-2025-109910.

Chen W, Di Y, Dong S, Wang J, Si Z. (2026). Neuromuscular training to prevent ACL injuries in female athletes: a systematic review and meta-analysis. Research in Sports Medicine, 34(3), 338–349. doi:10.1080/15438627.2025.2572716.

Chia L, De Oliveira Silva D, Whalan M, et al. (2022). Non-contact anterior cruciate ligament injury epidemiology in team-ball sports: a systematic review with meta-analysis by sex, age, sport, participation level, and exposure type. Sports Medicine, 52, 2447–2467. doi:10.1007/s40279-022-01697-w.

Crossley KM, Whittaker JL, Patterson B, et al. (2025). Female, woman and/or girl Athlete Injury pRevention (FAIR) practical recommendations: International Olympic Committee consensus meeting held in Lausanne, Switzerland, 2025. British Journal of Sports Medicine, 59(22), 1546–1559. doi:10.1136/bjsports-2025-110889.

Dos’ Santos T, Stebbings GK, Morse C, Shashidharan M, Daniels KAJ, Sanderson A. (2023). Effects of the menstrual cycle phase on anterior cruciate ligament neuromuscular and biomechanical injury risk surrogates in eumenorrheic and naturally menstruating women: a systematic review. PLOS ONE, 18(1), e0280800. doi:10.1371/journal.pone.0280800.

Elliott-Sale KJ, Minahan CL, Janse de Jonge XAKJ, et al. (2021). Methodological considerations for studies in sport and exercise science with women as participants: a working guide for standards of practice for research on women. Sports Medicine, 51, 843–861. doi:10.1007/s40279-021-01435-8.

Guthardt Y, Sargent D, Julian R. (2026). The influence of the menstrual cycle on muscle injuries—a systematic review and meta-analysis. Scientific Reports, 16, 3035. doi:10.1038/s41598-026-36763-0.

Hackney AC, Hansen M, Melin A. (2025). Menstrual cycle effects on sports performance and adaptations to training: a historical perspective. Scandinavian Journal of Medicine & Science in Sports, 35(8), e70107. doi:10.1111/sms.70107.

Herzberg SD, Motu’apuaka ML, Lambert W, Fu R, Brady J, Guise JM. (2017). The effect of menstrual cycle and contraceptives on ACL injuries and laxity: a systematic review and meta-analysis. Orthopaedic Journal of Sports Medicine, 5(7), 2325967117718781. doi:10.1177/2325967117718781.

Hewett TE, Zazulak BT, Myer GD. (2007). Effects of the menstrual cycle on anterior cruciate ligament injury risk: a systematic review. American Journal of Sports Medicine, 35(4), 659–668. doi:10.1177/0363546506295699.

Holtzman B, Popp KL, Tenforde AS, et al. (2022). Low energy availability surrogates associated with lower bone mineral density and bone stress injury site. PM&R, 14(5), 587–596. doi:10.1002/pmrj.12821.

MacMillan C, Olivier B, Viljoen C, Janse van Rensburg DC, Sewry N. (2024). The association between menstrual cycle phase, menstrual irregularities, contraceptive use and musculoskeletal injury among female athletes: a scoping review. Sports Medicine, 54(10), 2515–2530. doi:10.1007/s40279-024-02074-5.

Martínez-Fortuny N, Alonso-Calvete A, Da Cuña-Carrera I, Abalo-Núñez R. (2023). Menstrual cycle and sport injuries: a systematic review. International Journal of Environmental Research and Public Health, 20(4), 3264. doi:10.3390/ijerph20043264.

McNamara A, Harris R, Minahan C. (2022). ‘That time of the month’ … for the biggest event of your career! Perception of menstrual cycle on performance of Australian athletes training for the 2020 Olympic and Paralympic Games. BMJ Open Sport & Exercise Medicine, 8(2), e001300. doi:10.1136/bmjsem-2021-001300.

Mikkonen RS, Ihalainen JK, Bruinvels G, et al. (2026). Monitoring menstrual health in footballers: considerations for tracking menstrual and hormonal contraceptive cycles in the field to support performance. Sports Medicine, 56(Suppl 1), 11–43. doi:10.1007/s40279-025-02338-8.

Minahan C. (2025). Menstrual cycles and macrocycles: Science, not socials, is doing the heavy lifting. The Journal of Physiology, 603(5), 1023–1024. doi:10.1113/JP288096.

Mountjoy M, Ackerman KE, Bailey DM, et al. (2023). 2023 International Olympic Committee’s consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 57(17), 1073–1097. doi:10.1136/bjsports-2023-106994.

Ramezani F, Saki F, Tahayori B. (2024). Neuromuscular training improves muscle co-activation and knee kinematics in female athletes with high risk of anterior cruciate ligament injury. European Journal of Sport Science, 24(1), 56–65. doi:10.1002/ejsc.12046.

Rudolph SE, Caksa S, Gehman S, et al. (2021). Physical activity, menstrual history, and bone microarchitecture in female athletes with multiple bone stress injuries. Medicine & Science in Sports & Exercise, 53(10), 2182–2189. doi:10.1249/MSS.0000000000002676.

Tenforde AS, Carlson JL, Chang A, et al. (2017). Association of the Female Athlete Triad risk assessment stratification to the development of bone stress injuries in collegiate athletes. American Journal of Sports Medicine, 45(2). doi:10.1177/0363546516676262.

White L, Losciale JM, Squier K, et al. (2023). Combined hormonal contraceptive use is not protective against musculoskeletal conditions or injuries: a systematic review with data from 5 million females. British Journal of Sports Medicine, 57(18), 1195–1202. doi:10.1136/bjsports-2022-106519.