Sports · Part Five · The Whole Athlete and the Team
Lesson 51 / 64
The Female Athlete
The female athlete is not a smaller version of the male athlete; she is a distinct physiological system that rewards care built for how she is actually wired.
The female athlete is a physiological system with her own parameters. Pooled across sports her anterior cruciate ligament injury rate runs about 1.7 times the male rate, and in high-level team sport her overall injury rate runs lower than his. Menstrual cycle phase moves performance trivially and daily availability substantially. The Unified Model of Tone reads every one of those numbers as one input meeting a differently organized state.
Noncontact ACL incidence
0.14 against 0.05 per 1000 hours
Highest ratio in any sport type
5.51, fixed-object landing
Bone mineral around peak growth
39 percent in four years
Studies recording menstrual status
5.6 percent
The menstrual cycle.
A roughly monthly hormonal rhythm, with a follicular phase before ovulation and a luteal phase after it. Estrogen and progesterone rise and fall on different schedules, and every tissue carrying receptors for them reads that rhythm, ligament and muscle included.
How a sex difference reaches the knee.
The landing is arranged during the flight phase, before contact. Hip and knee position and muscle activation differ by sex in that instant, so the load arrives at a joint already organized one way or the other.
01What the measurements show
The Numbers Behind the Sex Difference
Eight findings on where the female athlete differs, where she does not, and what has never been measured.
02A distinct system
Sex Differences in the Athlete Run Deeper Than Size
The female athlete is a distinct physiological system, and the care that serves her best is built for that biology rather than scaled down from a male template. The difference starts below the level of proportions. More than 3,000 genes are differentially expressed in male and female skeletal muscle Haizlip 2015.
That review follows the consequences into fiber-type composition, myosin heavy chain expression and contractile function, and into the way thyroid hormone, estrogen and testosterone regulate each of them. Muscle running a different transcriptional program contracts on a different schedule. None of this is a ceiling on excellence. It is a map.
The same dosage does not produce the same response
Sex changes what a training dose does. A review of sex as a biological variable in exercise physiology states the finding that matters most for programming Ansdell 2020. The physiological response to equivalent dosages of exercise is not the same in males and females.
The clearest example runs in her favor. Female skeletal muscle is more resistant to the fatigue produced by equivalent dosages of high-intensity exercise. Integrative metabolic thresholds during exercise are influenced by sex differences spread across several physiological systems at once.
Read that map correctly and the programming writes itself. Endurance and fatigue resistance are strengths to be used rather than accommodated. Maximal strength is usually where the largest untapped gains sit, because it is the quality most often left untrained.
Specific adaptation to imposed demand does not discriminate. Her motor system recruits, learns and consolidates skill on the same principles as his, and the neural share of any early strength gain belongs to The Brain Runs the Body.
03The knee gap
The Female to Male Ligament Ratio Is About 1.7, and Six Is Too High
The female athlete does tear the anterior cruciate ligament more often than the male athlete, and the pooled size of that difference is smaller than the figure in common use. Across 58 studies, the incidence proportion was 3.5 percent in female athletes and 2.0 percent in male athletes Montalvo 2019. That is one athlete in 29 against one in 50.
The rate version of the same comparison gives an incidence rate ratio of 1.7, with a confidence interval of 1.4 to 2.2. Relative risk came in at 1.5. Amateur athletes carried the widest gap at 2.1, so the difference does not belong to elite competition.
Restrict the question to the noncontact mechanism and the gap widens. Across 45 cohort studies in 13 team ball sports, all of them built on cutting and jumping, noncontact ligament injuries arrived at 0.14 per 1000 player-hours in female athletes Chia 2022. In male athletes the same figure was 0.05. Noncontact mechanisms accounted for 63 percent of her ligament injuries against 50 percent of his.
The mechanism behind that share, the 40 milliseconds in which a valgus collapse loads the ligament, belongs to The Knee. What belongs here is the sex comparison, and it says the female athlete's excess risk sits almost entirely in the injury nobody caused.
Where the six-fold figure came from
The high ratios entered circulation before the pooling was done. A 2007 meta-analysis opens by noting that the female to male tear ratio had been reported as high as 9 to 1, then reports what the pooled data actually held Prodromos 2007.
Basketball returned 3.5 and soccer 2.67. Lacrosse returned 1.18 and alpine skiing 1.0, meaning no sex difference at all. Collegiate soccer rates were 0.32 for women and 0.12 for men, and basketball 0.29 against 0.08. A prospective screening study from 2005 opens by describing the disparity in high-risk sports as four to six fold Hewett 2005.
That is the source of the six-fold figure quoted for cutting and jumping sport. It described one era's framing rather than a pooled estimate, and the meta-analyses that followed cut it roughly in half.
The ratio belongs to the sport, not to the athlete
Sort sports by the demand they impose and the sex difference appears and disappears with the demand. In collision sports the rate ratio was 1.14, in limited-contact sports 1.21, and in sports classified as noncontact 1.49, none of them statistically significant Montalvo 2019.
In contact sports the ratio reached 3.00, at 1.88 against 0.87 injuries per 10,000 exposures. In fixed-object, high-impact rotational landing sports such as gymnastics it reached 5.51, at 4.80 against 1.75. Those sports carried the highest ligament injury rates for both sexes.
Adolescent data agree. Across 17,824,251 exposures and 1,235 ligament injuries, girls ran 0.084 injuries per 1000 exposures and boys 0.060, a relative risk of 1.40 Bram 2021. Basketball was the outlier at 4.14, girls' soccer carried the highest rate in the analysis at 0.166, and match play produced 8.54 times the practice rate for girls.
A difference that runs 1.0 in alpine skiing and 5.51 in fixed-object landing sports is not a property the athlete carries from sport to sport. It is what happens when a particular demand meets a particular system.
Where the sexes do not separate
Outside the knee, the injury ledger favors the female athlete. Pooling 20 prospective surveillance studies of high-level team sport, the overall injury rate ratio was 0.86, meaning significantly more injuries in male players Zech 2022.
Male players carried higher rates of upper extremity, hip and groin, thigh and foot injuries. Female players carried the higher anterior cruciate ligament rate at 2.15, with a confidence interval of 1.27 to 3.62. Match injuries, training injuries, severe injuries, concussions and ankle sprains showed no sex difference in that pooled set.
Any account of the female athlete built on general fragility has to explain why she is injured less often overall. The evidence describes one demand she meets differently, not a body that breaks more easily.
04How the landing is built
The Female Athlete Excess Risk Sits in How a Landing Is Organized
What separates the knee that tears from the knee that holds is the organization of the landing, and it can be measured months before anything happens. Researchers screened 205 female athletes in soccer, basketball and volleyball with three-dimensional motion capture during a jump landing, then waited Hewett 2005.
Nine ruptured the ligament. Compared with the 196 who did not, those 9 had landed with knee abduction angle 8 degrees greater and knee abduction moment 2.5 times greater. Ground reaction force ran 20 percent higher and stance time 16 percent shorter, so more motion and more force arrived in less time.
Knee abduction moment identified future injury with 78 percent sensitivity and 73 percent specificity, and the dynamic valgus measures returned a predictive r squared of 0.88. The ligament loads before the muscles catch it.
The landing is planned before the foot arrives
The pattern is set in advance. Three-dimensional video and muscle recordings from 36 recreational athletes performing a vertical stop-jump showed significant sex differences in the flight phase, before contact Chappell 2007.
The women prepared for landing with less knee flexion, less hip flexion, less hip abduction and less hip external rotation, with more knee internal rotation. Quadriceps activation before landing ran higher. Hamstring activation ran higher before contact and lower after it.
The authors conclude that lower extremity motion patterns during the landing are preprogrammed before landing. That is the whole argument in one sentence. What arrives at the knee is a plan the nervous system wrote in the air, and the tissue then has to live with it.
Quadriceps early, hamstrings late
The muscle record from the landing itself points the same way. Eight female and seven male collegiate basketball players were recorded electromyographically during jump landing Urabe 2005. Maximal voluntary contraction of vastus medialis between 15 and 45 degrees of knee flexion ran significantly higher in the women.
Mean hamstring activity across that whole range did not differ by sex. At 15, 20 and 25 degrees of knee flexion, the angles where the knee sits closest to straight, hamstring activity ran significantly lower in the female athletes.
Quadriceps contraction with the knee near extension drives the tibia forward. On foot plant she tends toward a quadriceps dominant strategy, and the hamstrings that resist anterior tibial translation are the muscles arriving late. The ligament takes the difference.
Sharpen joint position sense and hamstring timing, and the knee that protected itself a fraction too late learns to protect itself in time. That timing lives in muscle spindles and the spinocerebellar loops that schedule joint protection, which is exactly why it answers to training.
This is a coordination problem, which means it is a trainable one. Landing, deceleration and dynamic valgus run on the same proprioceptive and reflex circuitry that governs every skilled movement, and the receptors that supply it are the subject of Proprioception and Joint Position Sense.
What moves the number, and where it did not
Training the movement changes the rate. Pooling 18 controlled trials, 27,231 participants and 347 ligament injuries, neuromuscular training programs lowered risk from 1 in 54 to 1 in 111, an odds ratio of 0.51 Petushek 2019.
Dose was modest: 18.17 hours across a season, 24.1 minutes per session, 2.51 sessions per week. Programs for school-aged athletes returned an odds ratio of 0.38 against 0.65 for college and professional athletes. Landing stabilization work and lower body strength work carried the effect, and every program used trained implementers.
The same input has also produced nothing. In the 2007 pooled analysis, injury-reduction training lowered the soccer tear rate by 0.24 per 1000 exposures and did not lower the basketball rate at all Prodromos 2007. Two sports, one intervention, two results.
Programming that follows from these numbers is the subject of Injury Prevention and Load, which carries load management and the workload-ratio evidence in full.
05Cycle and performance
Cycle Phase Moves a Female Athlete's Measured Performance Trivially and Her Availability a Great Deal
The menstrual cycle changes what a female athlete can produce on a test day by very little. A network meta-analysis of 78 studies found performance trivially reduced in the early follicular phase compared with every other phase, at a median effect size of 0.06 McNulty 2020.
The largest single contrast, early follicular against late follicular, reached 0.14. Ranking the phases by likelihood of poor performance put early follicular at 30 percent and every other phase between 53 and 55. The authors classified the quality of the evidence as low, at 42 percent, and recommend an individual approach in place of a phase rule.
What moves is the athlete's week. A survey of 6,812 exercising women across six regions, none of them using combined hormonal contraception, recorded the symptoms they live with Bruinvels 2021. Mood changes and anxiety reached 90.6 percent, tiredness 86.2 percent, stomach cramps 84.2 percent and breast tenderness 83.1 percent.
Symptom load tracked behavior. Controlling for body mass index, training volume and age, each point on the symptom index raised the odds of missing or changing training by 9 percent. Missing a competition rose by 7 percent per point and taking pain medication by 9 percent.
Both results are true and they measure different things. One asks what she can produce on a chosen day in a laboratory. The other asks whether the session happens at all. A program that plans around the second gets more out of the athlete than one that argues about the first.
Knee laxity and injury across the cycle
Hormone state reaches the ligament. Pooling 21 studies and 68,758 participants, a meta-analysis of laxity data found significantly greater anterior knee laxity during the ovulatory phase than the follicular phase Herzberg 2017.
Four of the 5 studies of women not using hormonal contraception found the luteal phase least associated with ligament injury. The two largest and highest quality contraceptive studies suggested that hormonal contraceptives may be protective, with recent work indicating up to a 20 percent lower risk. The authors graded the overall strength of that evidence as low.
Read together with the landing data, this says the tissue and its timing both sit inside a hormonal rhythm. The rhythm is shared. The size of its effect on any individual athlete is not, which is why a phase rule keeps failing and an individual record keeps working.
What a cycle-aware program records
The standards for studying women as participants are now written down, and they double as a practical checklist. The working guide covers participant selection and design adaptations for the menstrual cycle, hormonal contraceptive use, pregnancy and the menopause Elliott-Sale 2021.
Its authors identify a shortage of specialist knowledge in the sport science community and an absence of agreement on terminology and gold-standard techniques as the reasons the field moved slowly. For a program, the equivalent is simple bookkeeping: cycle day, symptom load, sleep, training response, recorded against the athlete's own history rather than a population chart.
The endocrine side of that record runs through the whole body, and Fertility and Women's Health carries the physiology of hormonal regulation and the nervous system in the research library.
06The bone window
The Years That Build a Female Athlete's Skeleton Fall Inside Her Competitive Peak
Bone is a deadline, and the female athlete spends her most important deposit years inside her competitive peak. Bone area and bone mineral content were tracked at the total body, lumbar spine, total hip and femoral neck from age 8 to 30 Baxter-Jones 2011. Every measurement was aligned on years from peak height velocity rather than on birthday, which removes maturation from the comparison.
Total body bone mineral content reached its plateau 6 years after peak height velocity, which equates to age 18 in girls and 20 in boys. Bone area plateaued 1 to 2 years earlier than mineral content, so the frame is finished before the mineral that fills it.
The four years around peak height velocity carry the load. In that window 39 percent of adult total body bone mineral is accrued. At the lumbar spine the figure reaches 46 percent in females, and at the femoral neck 33 percent in both sexes.
The window to build a skeleton is narrow, and it closes during exactly the seasons of heaviest training and highest pressure. Mineral not laid down on that schedule cannot be repaid on it later, because maturation sets the schedule.
Energy is the input the skeleton reads
The pattern to recognize in this population is the simultaneous presence of low energy availability, menstrual dysfunction and reduced bone mineral density. It was named the female athlete triad and now sits inside relative energy deficiency in sport, which covers male athletes as well.
It begins with energy, meaning the fuel left for biological function once training has taken its share. Drop energy availability below roughly thirty kilocalories per kilogram of fat free mass and the body triages. The threshold figures, the trials behind them and the measurement error that clouds all of it belong to Body Composition.
The triage is fast and measurable. Bone resorption rises while bone formation falls. The hypothalamus throttles gonadotropin releasing hormone, estrogen drops, menses become irregular or stop, and the bone building signal goes quiet at the age the skeleton most needs it.
That is why the energy conversation is a performance conversation. Bone stress injury and the load that produces it belong to Injury Prevention and Load. When bone density becomes the clinical question, the measurement is dual energy X-ray absorptiometry read against an age and sex matched Z score, ordered and interpreted rather than performed in a chiropractic office.
Maturation timing runs underneath all of it, and the athlete who is still growing is a different system again, which The Youth Athlete carries in full. Fuel the athlete, protect the cycle, and the skeleton she carries into her thirties stays an asset.
07The measurement frontier
What Has Been Measured in the Female Athlete and What Has Not
The record on the female athlete is uneven by count, and the counts are known exactly. Across 1,441 sport and exercise medicine studies published between January 2021 and August 2023, female participants made up 17,648,509 of 40,152,860 people, or 43.95 percent Ose 2025.
The mean proportion of female participants per study was 40.22 percent. Female-only studies numbered 103, or 7.15 percent, against 268 male-only studies at 18.6 percent. Female participation rose from 39 percent a decade earlier, so the direction is steady.
The sharper number is the design one. Sixty-six studies, 5.6 percent of the total, considered menstrual status in the study design. Half a percent reached the top classification for handling it. The variable most specific to this athlete is recorded in about one paper in eighteen.
The standards for doing better are already published. A working guide sets out participant selection criteria and design adaptations for the menstrual cycle, hormonal contraceptive use, pregnancy and the menopause Elliott-Sale 2021. Its authors name disagreement over terminology and technique as what held the field back.
Why the pooled cycle result comes out trivial
The averaging explains the flat result. A network meta-analysis pools effects across women whose hormonal responses differ in size and timing, and a swing that is real inside one athlete cancels against an opposite swing in another McNulty 2020.
That is why the same review that reports a trivial pooled effect recommends an individual approach based on each woman's own response. The pooled number answers a population question. An athlete needs the within-athlete answer, and the within-athlete answer requires repeated measurement on the same person across her own cycle.
What is established is listed above with sources: the rate ratios, the landing kinematics, the laxity shift across phases, the symptom prevalence. What has never been recorded is all four regulatory readouts this section runs on, taken together, in one female athlete cohort, across a full cycle. That measurement is available with equipment programs already own.
08What we corrected
Five Claims Corrected or Removed From This Page
This page previously said that the female athlete sustains noncontact knee injury at roughly six times the male rate. The pooled evidence puts the ligament ratio at 1.7 overall and 2.15 in high-level team sport, reaching 5.51 in one narrow category of sport. The six-fold figure is gone and the sourced range replaces it.
Three physiological figures went with it. A maximal oxygen uptake differing by 20 to 30 percent once adjusted for size, a smaller stroke volume raising working heart rate, and greater slow twitch capacity within her sport. None could be traced to a source as stated, and the gene expression and fatigue resistance findings above replace them.
The bone figures also changed. The page claimed that 92 percent of adult bone mass is laid down by age 18 and 99 percent by 26, with a quarter accrued around menarche. Measurements aligned on peak height velocity replace all three Baxter-Jones 2011.
Two energy availability figures, amenorrhea running about 20 times higher in athletes and lumbar spine density running up to 20 percent lower, are not repeated here without their sources. That literature is carried by Body Composition.
A block quotation set above the closing section carried Dr. Jason Dulberg's name. Nothing in his recorded teaching or writing contains those words, so the attribution is gone. The position it stated is made here in the page's own voice. The female athlete is not delicate; she is specific.
09The model's claim
The Sex Difference Is a Difference in What the Demand Meets
Two kinds of statement sit on this page and they carry different weight. The rate ratios, the landing kinematics, the laxity analysis, the symptom survey and the participation counts are the work of the investigators named beside each one. The reading that follows is the Unified Model of Tone's, and it is ours to defend.
Start with the number that refuses to hold still. The female to male ligament ratio is 1.0 in alpine skiing, 1.18 in lacrosse, 1.40 across adolescent sport, 2.67 in soccer, 3.5 in basketball and 5.51 in fixed-object rotational landing. A property the athlete carries would travel with her from sport to sport.
This one appears when a particular demand arrives and vanishes when it does not. The model reads that as the input law doing its work: the effect of an event is determined by how that event interacts with the organism's existing tone. Landing demand is the event. Her organization is the tone it meets.
The cycle data say the same thing from the other direction. A hormonal shift is an input, it meets a differently organized system in every athlete, and averaging those responses across women returns a trivial effect while the response inside any one of them stays real.
What the care is aimed at
The durability of the female athlete is built in the nervous system, the same place her injury risk and her recovery live. Adjusting the knee, the hip and the spine feeds clean proprioceptive signal into the circuits that time landing and deceleration. A joint that senses itself accurately defends itself before the ligament ever reaches end range.
Coordination is neurology, and neurology is trainable at any level of competition. Recovery answers to the same system. Heavy training, low fuel and life stress register first in autonomic balance, the central integrative state that sets the readiness underneath performance, readable in heart rate variability and resting heart rate.
Build the program around her real physiology and the result is a longer, sharper, more resilient career.
The prediction this page makes
Take one squad of female athletes through one menstrual cycle and record four things on the same days. Knee abduction moment during a standardized drop landing. Knee joint position sense error in degrees. RMSSD. Time to return to baseline after a standardized load test. Log cycle day and symptom load beside them.
The model predicts those four move together within each athlete, and that the size of the swing differs between athletes rather than following a phase rule that holds for all of them. That prediction is different from a hormone-effect account, which expects the same phase to produce the same shift in everyone.
It is a claim about how performance is organized rather than a claim about what treatment does. Every instrument it names already sits in a well-run program, and Tone and the Athlete's Edge sets out the same four readouts as the section's central question.
If abduction moment at landing, joint position sense error, RMSSD and time to return to baseline are shown to move together within the same female athletes across a cycle, the unification claim is confirmed.
10The tone reading
The Female Athlete as One Regulated System
The female athlete's record already carries three signatures of tone, each inside a measurement someone is already taking.
Input quality
Neuromuscular training cut ligament risk from 1 in 54 to 1 in 111, and further in school-aged athletes. One input, two states, two sizes of effect.
Coupling
Ovarian hormones run on a monthly rhythm and a landing is organized in milliseconds. Knee laxity rising in the ovulatory phase is those two rhythms meeting.
Time course
Bone answers on a decade. In the four years around peak height velocity, 39 percent of adult total body bone mineral is laid down.
The remaining foundations show up in her record as well. Prediction is the landing plan written in the air before contact, which is exactly where the stop-jump differences appeared. Load is the demand a given sport hands her, and it decides whether the ligament ratio reads 1.0 or 5.51. Constraint covers a knee held too tightly as well as one held too loosely, which is the difference between guarding a joint and organizing it. Gain is how strongly the system answers a given input, and it is what a landing block changes. Set-point is the value a regulator defends, and reproductive signaling is where an underfueled system stops defending first. Oscillation is the monthly rhythm itself, the carrier every one of these readings rides on. The Unified Model of Tone treats them as readings of one variable rather than a list of separate ones.
11Where this sits
How This Page Relates to the Rest of the Library
Seven places the female athlete argument continues, each with the claim that earns the link.
Owns the noncontact mechanism itself, including the 40 milliseconds in which valgus collapse loads the ligament and the 55 percent noncontact share.
Carries low energy availability, the hormonal consequences, and the measurement error that makes composition numbers a poor readout of an athlete.
Holds maturation timing and early specialization, which run underneath the four years that build most of the skeleton.
Carries the workload-ratio evidence and its critiques, which is the dosing question this page keeps handing back to the program.
Owns RMSSD and the variability-structure readout that the cycle prediction on this page depends on.
Owns joint position sense error in degrees, the second instrument in this page's four-measure prediction.
The keystone lesson, where the one-variable claim is stated in full and given the study design that would settle it.
12Questions athletes ask
Questions Athletes Ask
Why do female athletes tear the ACL more often than male athletes?
Pooled across 58 studies the incidence rate ratio is 1.7, so about one female athlete in 29 tears the ligament against one male athlete in 50. Restricted to noncontact mechanisms in team ball sports the rates run 0.14 against 0.05 per 1000 player-hours. The difference lives in how a landing is organized rather than in weak tissue. Prospective screening found the athletes who later ruptured landing with 8 degrees more knee abduction and 2.5 times the abduction moment. That pattern is set before the foot touches the floor.
Where did the claim that women tear the ACL six times more often come from?
From the era before the pooling was done. A 2007 meta-analysis records that ratios as high as 9 to 1 had been reported, and a 2005 prospective study describes the disparity in high-risk sports as four to six fold. When that 2007 analysis pooled the data it returned 3.5 for basketball, 2.67 for soccer, 1.18 for lacrosse and 1.0 for alpine skiing. Later meta-analyses put the overall figure near 1.7. The six-fold number described one era's framing rather than a pooled estimate.
Does the menstrual cycle affect athletic performance?
Barely, on a test day. A network meta-analysis of 78 studies found performance trivially reduced in the early follicular phase, at a median effect size of 0.06, with the largest single contrast reaching 0.14. What moves more is availability. Among 6,812 exercising women, 90.6 percent reported mood changes or anxiety and 86.2 percent reported tiredness, and a higher symptom load raised the odds of missing or changing training. Capacity measured in a laboratory and the ability to complete a training week are two different readings.
Should a female athlete plan her training around her cycle?
Plan around the athlete rather than the phase. Pooled cycle data average across women whose responses differ in size and timing, which is why the same review reporting a trivial effect recommends an individual approach. The record worth keeping is hers: cycle day, symptom load, sleep, and how a standard session felt, held over months. Anterior knee laxity does run higher in the ovulatory phase, so landing volume is a reasonable thing to track against her own calendar rather than against a general rule.
What is the female athlete triad, and how does RED-S relate to it?
The triad is the simultaneous presence of low energy availability, menstrual dysfunction and reduced bone mineral density. Relative energy deficiency in sport is the broader framing that replaced it, and it covers male athletes too. Energy is the entry point, meaning the fuel left for biological function once training has taken its share. Threshold figures and measurement problems sit on the Body Composition lesson. Timing is why it matters here: adult total body bone mineral reaches its plateau around age 18 in girls.
Do landing and neuromuscular training programs actually change knee injury rates?
In pooled trials it does. Across 18 controlled trials and 27,231 participants, neuromuscular training lowered anterior cruciate ligament risk from 1 in 54 to 1 in 111, an odds ratio of 0.51, on roughly 18 hours spread across a season. School-aged athletes showed the larger effect at 0.38. The result is not uniform. An earlier pooled analysis found such training lowered the soccer tear rate and did not lower the basketball rate at all. One intervention, two sports, two outcomes.
What does a chiropractic neurologist measure in a female athlete?
Joint position sense, balance, eye movements, reaction time and autonomic recovery, which are readouts of the same nervous system that times a landing. The examination is drug free and fully anti-doping compliant, which matters for anyone under testing. Care is directed at the quality of the sensory signal reaching the circuits that organize deceleration, and it is documented alongside the strength and athletic training staff rather than in place of them. Imaging and bone density testing are referred out and interpreted, never performed in the office.
13The sources
References
18 primary sources, each linked to its record. Figures quoted on this page were checked against the published abstract.
Related evidence