Female Athlete Physiology

Cycles vary between women and from month to month; 21-35 days is the usual normal range, 28 is only an average.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

The early follicular phase is the low-hormone point of the cycle, which researchers use as a reference phase.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

Oestrogen rises through the follicular phase to a peak just before ovulation; progesterone is still low.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

A surge of LH from the pituitary triggers release of the egg; ovulation tests detect this surge in urine.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

After ovulation the corpus luteum produces progesterone and oestrogen, both elevated in the mid-luteal phase.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

Progesterone raises resting core temperature by around 0.3-0.5 C after ovulation.

Source: Baker et al., Sleep Med Clin 2020 · recall

Without hormone or ovulation measures, a "luteal" test may fall in the wrong phase or in a cycle that never ovulated.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

A woman can bleed regularly without ovulating or with a short luteal phase; these disturbances are common in exercising women.

Source: De Souza et al., Hum Reprod 2010 · recall

Eumenorrhoea means cycles of normal length with evidence of ovulation and a sufficient luteal phase.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

Urinary LH tests and a mid-luteal progesterone measure confirm ovulation better than calendar-based estimates.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · applied

Progesterone shifts thermoregulatory thresholds upward, so sweating and skin blood flow begin at a higher core temperature.

Source: Charkoudian & Stachenfeld, Compr Physiol 2014 · recall

Progesterone stimulates the respiratory centre, increasing ventilation in the luteal phase.

Source: Charkoudian & Stachenfeld, Compr Physiol 2014 · recall

Oestrogen promotes lipolysis and fat oxidation and may spare muscle glycogen.

Source: Oosthuyse & Bosch, Sports Med 2010 · recall

Women had lower respiratory exchange ratios and used less muscle glycogen than men at the same relative effort.

Source: Tarnopolsky et al., J Appl Physiol 1990 · recall

Starting from a higher resting core temperature narrows the margin before heat strain builds.

Source: Charkoudian & Stachenfeld, Compr Physiol 2014 · applied

Oestrogen and progesterone influence fluid-regulating hormones, and some women notice fluid retention before a period.

Source: Stachenfeld, Exerc Sport Sci Rev 2008 · recall

Group-level effects are trivial to small, while individual women may notice consistent patterns.

Source: McNulty et al., Sports Med 2020 · recall

Surveys of athletes report cramps, fatigue, bloating and sleep disturbance as the most frequent symptoms.

Source: Bruinvels et al., Br J Sports Med 2021 · recall

Individual patterns matter more than group averages; tracking symptoms lets training be adjusted where it helps.

Source: McNulty et al., Sports Med 2020 · applied

Higher core temperature and altered fluid regulation mean heat and fluid strategies deserve extra attention.

Source: Stachenfeld, Exerc Sport Sci Rev 2008 · applied

Synthetic oestrogen and progestin suppress the pituitary signals, stopping ovulation and flattening natural hormone swings.

Source: Elliott-Sale et al., Sports Med 2020 · recall

The bleed is caused by stopping the hormones, not by the natural cycle.

Source: Faculty of Sexual and Reproductive Healthcare guideline 2019 · recall

Pooled data suggested slightly inferior performance compared with naturally menstruating women, with a trivial average effect.

Source: Elliott-Sale et al., Sports Med 2020 · recall

The hormonal IUD acts mainly locally; ovulation often continues, especially with lower-dose devices.

Source: Faculty of Sexual and Reproductive Healthcare guideline 2019 · recall

Bleeding on the pill does not show whether the natural cycle is healthy, so low energy availability can go unnoticed.

Source: Mountjoy et al., Br J Sports Med 2023 (IOC REDs consensus) · recall

Depot medroxyprogesterone acetate lowers oestrogen and is associated with bone loss that is largely reversible after stopping.

Source: FDA boxed warning for DMPA (2004) · recall

Tailored or continuous regimens that skip or shorten the pill-free interval are considered safe for most users.

Source: Faculty of Sexual and Reproductive Healthcare guideline 2019 · applied

Synthetic hormones and suppressed natural hormones create a distinct profile that affects study results.

Source: Elliott-Sale et al., Sports Med 2021 (methodological recommendations) · recall

A monophasic pill gives the same dose daily, producing relatively stable exogenous hormone levels.

Source: Elliott-Sale et al., Sports Med 2020 · recall

Mood changes, bleeding patterns or other side effects that affect training are good reasons to review options.

Source: Faculty of Sexual and Reproductive Healthcare guideline 2019 · applied

About 36% of female marathon runners reported heavy menstrual bleeding, and many said it affected their training.

Source: Bruinvels et al., Br J Sports Med 2016 · recall

Menstrual losses on top of sweat, gut and foot-strike losses, plus often lower intake, raise the risk.

Source: Sim et al., Eur J Sport Sci 2019 · recall

Reviews estimate iron deficiency in 15-35% of female and 5-11% of male athletes.

Source: Sim et al., Eur J Sport Sci 2019 · recall

Needing to change products every 1-2 hours, flooding or clots over about 2.5 cm suggest heavy bleeding.

Source: NICE guideline NG88 (2018) · recall

Effective treatments exist, and untreated heavy bleeding is a leading cause of iron deficiency in women.

Source: NICE guideline NG88 (2018) · applied

Sports medicine guidance often uses ferritin under about 35 ug/L to flag iron deficiency, higher than general population cut-offs.

Source: Clenin et al., Swiss Med Wkly 2015 · recall

Fatigue plus heavy bleeding points strongly to possible iron deficiency, which a ferritin and haemoglobin test can confirm.

Source: Sim et al., Eur J Sport Sci 2019 · applied

The levonorgestrel IUD and combined pills are established treatments that reduce menstrual blood loss.

Source: NICE guideline NG88 (2018) · recall

Red-cell mass expands and the placenta and baby take iron, raising requirements, especially later in pregnancy.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Few women know typical blood loss volumes, so heavy bleeding is often considered normal for them.

Source: Bruinvels et al., Br J Sports Med 2016 · recall

ACOG and WHO recommend at least 150 minutes per week of moderate aerobic activity in uncomplicated pregnancy.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Exercise lowers the risk of gestational diabetes, pre-eclampsia and excessive weight gain.

Source: Davenport et al., Br J Sports Med 2018 · recall

In the supine position the enlarged uterus can compress the inferior vena cava, reducing venous return.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Scuba diving is contraindicated because the fetus is not protected from decompression sickness.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Bleeding, fluid leakage, chest pain, dizziness or regular painful contractions are warning signs to stop.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Core temperatures above about 39 C have been linked to neural tube risk in early pregnancy; typical exercise rarely reaches this.

Source: Ravanelli et al., Br J Sports Med 2019 · recall

Plasma volume expands substantially, raising blood volume by around 40-50% by the third trimester.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Relaxin softens connective tissue to prepare the pelvis, which may slightly increase joint laxity.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Evidence on high-intensity training is limited, so elite athletes should be guided individually by medical staff.

Source: Bo et al., Br J Sports Med 2016-2018 (IOC expert group) · recall

Activities with a high risk of falling or impact are discouraged; stationary cycling avoids the fall risk.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · applied

Goom, Donnelly and Brockwell advise a return to running no earlier than about 12 weeks, after low-impact work.

Source: Goom, Donnelly & Brockwell, Returning to running postnatal 2019 · recall

The guideline recommends a graded low-impact programme and pelvic floor rehabilitation before running.

Source: Goom, Donnelly & Brockwell, Returning to running postnatal 2019 · recall

The two sides of the rectus abdominis separate along the linea alba; it is common during and after pregnancy.

Source: Sperstad et al., Br J Sports Med 2016 · recall

Sperstad found diastasis recti in about 60% of women at six weeks postpartum, falling to about a third at a year.

Source: Sperstad et al., Br J Sports Med 2016 · recall

Moderate exercise does not affect milk volume or composition in a way that harms the baby.

Source: ACOG Committee Opinion 804, Obstet Gynecol 2020 · recall

Urinary or faecal leakage, a sense of heaviness or pelvic pain point to pelvic floor dysfunction that needs assessment.

Source: Goom, Donnelly & Brockwell, Returning to running postnatal 2019 · recall

Calcium is drawn from bone for milk, causing reversible loss that generally recovers after breastfeeding ends.

Source: Kovacs, Physiol Rev 2016 · recall

A Caesarean is major abdominal surgery; the scar and abdominal wall need to heal before loading increases.

Source: Goom, Donnelly & Brockwell, Returning to running postnatal 2019 · recall

Broken sleep and the demands of a new baby reduce the capacity to recover from training.

Source: Goom, Donnelly & Brockwell, Returning to running postnatal 2019 · applied

Passing a time point is not enough; a pelvic health check and a graded build reduce the risk of problems.

Source: Goom, Donnelly & Brockwell, Returning to running postnatal 2019 · applied

Stress urinary incontinence is leakage on exertion when abdominal pressure exceeds pelvic floor support.

Source: Teixeira et al., Int Urogynecol J 2018 · recall

A meta-analysis estimated prevalence at about 36%, highest in high-impact sports.

Source: Teixeira et al., Int Urogynecol J 2018 · recall

Repeated high ground-reaction forces load the pelvic floor most.

Source: Teixeira et al., Int Urogynecol J 2018 · recall

Pelvic floor muscle training is the recommended first-line treatment, ideally guided by a specialist physiotherapist.

Source: NICE guideline NG123 (2019) · recall

Multiplanar breast displacement during running reached around 15 cm in unsupported conditions.

Source: Scurr et al., J Appl Biomech 2010 · recall

Around 32% of female runners at the London Marathon reported breast pain.

Source: Brown et al., J Sci Med Sport 2014 · recall

Reduced breast support shortened stride length, which over a marathon could add distance-related cost.

Source: Milligan et al., J Sports Sci 2015 · recall

Breast pain and embarrassment are reported barriers to physical activity, especially for larger-breasted women.

Source: Brown et al., J Sci Med Sport 2014 · recall

Leakage under fatigue is common but treatable; specialist assessment and training are the first step.

Source: NICE guideline NG123 (2019) · applied

Well-fitted, high-support bras reduce breast displacement and pain; poor fit is common.

Source: Scurr et al., J Appl Biomech 2010 · applied

Menopause is confirmed retrospectively after 12 consecutive months without menstruation.

Source: NICE guideline NG23 (2015, updated 2024) · recall

The average age of natural menopause is around 51.

Source: NICE guideline NG23 (2015, updated 2024) · recall

In the years before menopause, oestrogen and progesterone fluctuate widely and cycles become irregular.

Source: NICE guideline NG23 (2015, updated 2024) · recall

Falling oestrogen accelerates bone loss, fastest in the first few years after the final period.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

Supervised heavy resistance and impact training improved spine and hip bone measures without serious adverse events.

Source: Watson et al., J Bone Miner Res 2018 · recall

Hot flushes and night sweats are the classic vasomotor symptoms and can disturb sleep and recovery.

Source: NICE guideline NG23 (2015, updated 2024) · recall

After menopause, fat distribution shifts towards visceral abdominal storage.

Source: Lovejoy et al., Int J Obes 2008 · recall

Loading helps counter the accelerated loss of muscle and bone that follows falling oestrogen.

Source: Watson et al., J Bone Miner Res 2018 · recall

Hormone therapy prevents postmenopausal bone loss and lowers fracture risk; its use depends on individual risks and symptoms.

Source: NICE guideline NG23 (2015, updated 2024) · recall

Symptoms can be treated, and adjusting recovery, strength work and sleep strategies supports training through the transition.

Source: NICE guideline NG23 (2015, updated 2024) · applied

The ACSM named the Triad in 1992 as disordered eating, amenorrhoea and osteoporosis, later refined to spectrums.

Source: Otis et al., Med Sci Sports Exerc 1997 (ACSM position stand) · recall

Energy availability, menstrual function and bone density became spectrums, with low energy availability as the driver.

Source: Nattiv et al., Med Sci Sports Exerc 2007 (ACSM position stand) · recall

Secondary amenorrhoea is the absence of menses for at least three consecutive months in a woman who previously menstruated.

Source: De Souza et al., Br J Sports Med 2014 (Triad consensus) · recall

Energy deficiency and stress suppress hypothalamic signalling (GnRH), lowering oestrogen and stopping cycles.

Source: Gordon et al., J Clin Endocrinol Metab 2017 (Endocrine Society guideline) · recall

Z-scores compare with same-age, same-sex peers; T-scores are meant for postmenopausal women.

Source: De Souza et al., Br J Sports Med 2014 (Triad consensus) · recall

Oestrogen limits osteoclast activity; when it falls, bone resorption outpaces formation.

Source: Brukner & Khan, Clinical Sports Medicine (5th ed.) · recall

The pill restores bleeding but not the energy deficiency; oral oestrogen also suppresses IGF-1, which bone needs.

Source: Ackerman et al., Br J Sports Med 2019 · recall

Transdermal oestradiol with cyclic progesterone increased bone density, while the combined oral pill did not.

Source: Ackerman et al., Br J Sports Med 2019 · recall

Female athletes with amenorrhoea or oligomenorrhoea have a markedly higher risk of bone stress injury.

Source: De Souza et al., Br J Sports Med 2014 (Triad consensus) · recall

Missing periods plus a bone injury call for assessment of energy availability, hormones and bone, with a team approach.

Source: De Souza et al., Br J Sports Med 2014 (Triad consensus) · applied

Analyses of Ironman results find the sex difference smallest in swimming and larger in cycling and running.

Source: Lepers, Med Sci Sports Exerc 2008 · recall

For many tasks, particularly sustained isometric and some dynamic contractions, women show less fatigability.

Source: Hunter, Acta Physiol 2014 · recall

In the Boston Marathon study, female sex was a risk factor, largely explained by lower body mass, longer times and overdrinking.

Source: Almond et al., N Engl J Med 2005 · recall

Women generally have lower sweat rates, partly explained by lower metabolic heat production.

Source: Gagnon & Kenny, J Physiol 2012 · recall

When matched for body size, fitness and heat production, many apparent sex differences shrink.

Source: Gagnon & Kenny, J Physiol 2012 · recall

Women tend to show a greater relative area of type I fibres, linked to their fatigue resistance.

Source: Hunter, Acta Physiol 2014 · recall

Small female fields and self-selection make it hard to compare the best performances fairly.

Source: Hunter et al., Med Sci Sports Exerc 2023 (ACSM consensus) · recall

Men's higher haemoglobin, larger hearts and more lean mass, driven largely by testosterone, give a higher VO2max.

Source: Hunter et al., Med Sci Sports Exerc 2023 (ACSM consensus) · recall

Women oxidise relatively more fat at the same relative intensity, though carbohydrate intake remains important.

Source: Tarnopolsky et al., J Appl Physiol 1990 · applied

Differences in fuel use, heat, fatigue and hormones mean findings from men may not transfer directly; individual monitoring helps.

Source: Hunter et al., Med Sci Sports Exerc 2023 (ACSM consensus) · applied