S

S5SJ

Owmpfpdd

5

Ooi

mafscp(mrAsewm

atespnls

eat

S

ports and Performing Arts Medicine

ports and Performing Arts Medicine:. Special Populations

tuart Willick, MD, Cedric K. Akau, MD, Mark A. Harrast, MD, Seneca A. Storm, MD,

onathan T. Finnoff, DO

ShC8eD

ChmSD

MmpWD

SRlD

JRCD

bjective: This self-directed learning module highlights common conditions associatedith specific populations. It is part of the study guide on sports and performing artsedicine in the Self-Directed Physiatric Education Program for practitioners and trainees inhysical medicine and rehabilitation. Using a case vignette format, this article specificallyocuses on the osteoarthritis and cardiac safety in the senior athlete, hip problems in theediatric athlete, classification of athletes with disabilities, and the female triad and exerciseuring pregnancy in female athletes. The goal of this article is to assist the learner ineveloping an understanding of issues related to specific athletic populations.

.1 Clinical Activity: Discuss the management of an athletic 70-year-old individualwith knee pain due to osteoarthritis.

steoarthritis (OA), the most prevalent form of arthritis, affects more than 60% of adultsver the age of 50 years. The joint most commonly affected is the knee [1]. Because this joints important in mobility, it is essential to understand the management of knee OA.

The goal in treating knee OA is to maximize function through the judicious use of aultifaceted treatment plan that includes pain relieving modalities, medications, injections,

nd bracing. This treatment plan must be coordinated with a rehabilitation programocusing on decreasing pain, reducing swelling, promoting early range-of-motion (ROM),trengthening, and a functional return to athletic activities. Swelling is controlled byryotherapy, leg elevation, compression and relative rest. Four grams or less of acetamino-hen daily can effectively treat OA pain [2]. Nonsteroidal anti-inflammatory medicationsNSAIDs) are more effective in reducing pain and swelling than acetaminophen, but have aore concerning side effect profile, especially in the elderly. Therefore, NSAIDs should be

eserved for acetaminophen nonresponders and their duration should be limited [2].lthough intra-articular corticosteroids and intra-articular hyaluronic acid demonstrateimilar reduction in knee OA pain 1 to 4 weeks postinjection, the hyaluronic acid is moreffective at 5 to 13 weeks after injection [1,3]. The use of functional unloader braces and heeledges (medial wedge for lateral compartment OA and lateral wedge for medial compart-ent OA) are efficacious in cases of biomechanical malalignment [1].The first phase of the rehabilitation program should begin with range-of-motion (ROM)

nd isometric quadriceps muscle exercises. Quadriceps “re-education” can be facilitatedhrough galvanic electrical stimulation or biofeedback [1]. A simple isometric quadricepsxercise is the supine straight leg raise (SLR). Ankle weights can be added once the patientuccessfully completes a set of SLRs without an extensor lag (bend in the knee). Once theatient has successfully completed this phase, they can progress to the second phase ofon-weight bearing open kinetic-chain exercises such as a seated knee extension. Patel-

ofemoral pain can be exacerbated by these exercises, so the patient with anterior knee painhould proceed with caution.

The third phase of rehabilitation consists of closed kinetic-chain exercises. Thesexercises require the foot to remain fixed on a weight or stable surface while the hip, knee,nd ankle move simultaneously around this fixed point (ie, leg press or squat). By this stage,

he patient should have at least 100° of ROM. Closed kinetic-chain exercises are more

DC

PM&R © 2009 by the American Academy of P1934-1482/09/$36.00

Printed in U.S.A.78

.W. Division of Physical Medicine and Re-abilitation, University of Utah Orthopaediclinic, 590 S Wakara Way, Salt Lake City, UT4108. Address correspondence to: S.W.;-mail: stuart.willick@hsc.utah.eduisclosure: nothing to disclose

.K.A. Division of Physical Medicine and Re-abilitation, University of Hawaii, and Depart-ent of Sports Medicine and Rehabilitation,

traub Clinic and Hospital, Honolulu, HIisclosure: nothing to disclose

.A.H. Spine and Sports Fellowship, Depart-ents of Rehabilitation Medicine and of Ortho-

edics and Sports Medicine, University ofashington, Seattle, WAisclosure: nothing to disclose

.A.S. Department of Physical Medicine andehabilitation, Michigan State University Col-

ege of Osteopathic Medicine, Lansing, MIisclosure: nothing to disclose

.T.F. Department of Physical Medicine andehabilitation, College of Medicine, Mayolinic, Rochester, MNisclosure: nothing to disclose

isclosure Key can be found on the Table ofontents and at www.pmrjournal.org

hysical Medicine and RehabilitationSuppl. 1, S78-S82, March 2009

DOI: 10.1016/j.pmrj.2009.01.023

frm

ssepguaaaOa

pa

5

AprpbsnhTp[p

tspacm

rtgow

mEgmmcc

oi

paHcecmi

csswcs

cidsesdt

5

TupsP

tfmdt

pti

mmawn

Rfi

S79PM&R Vol. 1, Iss. 3, Supplement 1, 2009

unctional than open kinetic-chain exercises and incorpo-ate, balance, proprioception and cocontraction of all theuscles surrounding the joint [1].The goal of the fourth stage is to return the athlete to their

port while minimizing the risk of re-injury. This phasehould include low impact, sport-specific concentric andccentric closed kinetic-chain exercises. Before starting thishase, the athlete must have at least 120° of ROM, a normalait, be able to climb and descend stairs, and run without these of compensatory mechanisms [1]. Sport-specific skillsnd movement patterns along with neuromuscular timingnd responsiveness are initiated with a gradual return to fullthletic participation [1]. Depending on the severity of theA, the patient may be unable to return to high impact

thletic activities.The final stage of rehabilitation is a maintenance exercise

rogram in which the athlete maintains strength, flexibility,nd balance.

.2 Educational Activity: Describe the medical eval-uation of a 54-year-old person who would like tobegin an exercise program.

cardiac risk factor assessment should be performed oneople interested in beginning an exercise program. Cardiacisk factors include hypercholesterolemia (240 mg/dL), hy-ertension as evidenced by high systolic (S) and diastolic (D)lood pressures (BP), (ie, SBP 140 mm Hg, DBP 90 mm Hg),moking, diabetes, and a family history of premature coro-ary artery disease (ie, history of a first degree relative with aeart attack or sudden cardiac death before age 60 years).he greater the number of risk factors, the more likely theatient will benefit from screening with an exercise stress test4]. A history of cardiac symptoms such as chest pain oralpitations is another indication for testing.

Asymptomatic men older than 45 years and women olderhan 55 years who have notable risk factors should becreened by means of exercise testing. Asymptomatic diabeticersons may benefit from earlier testing, particularly if theyre planning on performing moderate to high intensity exer-ise [5,6]. Screening persons with lower risk is not recom-ended [4,7].Exercise stress testing can be used to screen individuals at

isk of developing hypertension. In asymptomatic, normo-ensive patients, an exaggerated peak systolic blood pressurereater than 214 mm Hg during exercise, or elevated systolicr diastolic pressure 3 minutes after exercise, is associatedith an increased risk of hypertension [6].The standard treadmill electrocardiogram (ECG) is the

ost appropriate test for individuals with a normal restingCG who are able to use the treadmill. The treadmill hasreater diagnostic sensitivity than the bicycle ergometer. Theost commonly used type of exercise stress testing is theaximal test. Maximal testing requires the individual to

ontinue exercising until failure, or until the desired testing

riteria are met. The participant should reach more than 85% m

f their age-predicted maximal heart rate. Submaximal test-ng is more appropriate for hospitalized patients [5].

The Bruce protocol is the most commonly used exerciserotocol. It includes 8 3-minute stages starting at 1.7 mph at0% grade, gradually increasing to 5.5 mph at a 20% grade.owever, the Bruce protocol tends to overestimate exercise

apacity. It may be too demanding for those with limitedxercise capacity and too short for those with high exerciseapacity. For these groups, an exercise protocol that reachesaximal capacity in 8-12 minutes using smaller increments

n workload should be considered [5].The exercise stress test is positive if any of the following

riteria are met [8]: (1) horizontal or down-sloping ST-egment depression greater than or equal to 1.0mm; (2) STegment elevation greater than or equal to 1.0mm; (3) U-ave inversion; (4) exercise-induced hypotension; (5) exer-

ise-induced angina; (6) appearance of an S3 or S4 heartound, or a heart murmur during exercise.

Absolute contraindications to exercise testing include re-ent change in resting ECG, recent complicated myocardialnfarction, unstable angina, uncontrolled arrhythmias, thirdegree atrioventricular block, acute congestive heart failure,evere aortic stenosis, and recent systemic or pulmonarymbolus [7]. In patients with known hypertension, it isuggested that a systolic pressure above 200 mm Hg or aiastolic greater than 110 mm Hg are relative contraindica-ions to exercise testing [6].

.3 Clinical Activity: Describe the importance of a hipexamination in a 12-year-old child who presentswith knee and thigh pain.

he sports medicine practitioner should be familiar with twoncommon yet serious pediatric hip disorders that canresent as hip pain, knee pain or merely as a limp. These arelipped capital femoral epiphysis (SCFE) and Legg-Calve-erthes disease [9].

Slipped capital femoral epiphysis is an idiopathic condi-ion in which the proximal femoral epiphysis subluxes off theemur, usually in a backward direction [10]. The presumedechanism is weakness of the physeal plate. Most often, itevelops during periods of accelerated growth shortly afterhe onset of puberty.

The condition is diagnosed based on a careful history,hysical examination, observation of gait, and radiographs ofhe hip. It is 2 to 3 times more common in boys than girls, ands more common in overweight children.

Symptoms may progress insidiously without trauma, oray present acutely with minor trauma or no trauma at all. Inild cases, the patient will complain of hip or knee pain andlimp. In severe cases, the patient will be unable to bear anyeight on the affected leg. The affected leg is usually exter-ally rotated and may appear to be shorter.

Symptoms will be reproduced with passive hip rotation.adiographs are diagnostic. Open reduction and internalxation is the treatment of choice. Early diagnosis and treat-

ent provide better outcomes than delayed treatment.

ttC[yam

tcs

cmTrs

areyfoo

pCeppfi

5

TpwTalaa

tmppCtitsb

TIsiacu

lPafitcanTtoaIptd“Dub

mriatstotfaewitfa

tqtpfi

5

S80 Willick et al SPECIAL POPULATIONS

Legg-Calve-Perthes disease can have a similar presenta-ion to SCFE but on average presents in a younger popula-ion, usually between ages 4 and 8 years. However, Legg-alve-Perthes can present between the ages of 2 and 12 years

11]. It is idiopathic avascular necrosis of the femoral epiph-sis. It is bilateral in 10%-20% of patients. When both hipsre involved, they are usually affected successively, not si-ultaneously. A family history is present in 6% of patients.Boys are affected 3 to 5 times more often than girls, and

he incidence increases in low socioeconomic groups and inhildren with a low birth weight. Girls and children of eitherex who present after age 8 have a worse prognosis.

As with SCFE, the child with Legg-Calve Perthes diseasean present with hip pain, knee pain, a limp, and impairedotion. Abduction and external rotation are lost early on.he initial imaging study of choice is radiographs. Magneticesonance imaging (MRI) is more sensitive during earlytages.

For mild and moderate cases, protected weight bearingnd supportive care are indicated to allow the femoral head toevascularize and the secondary ossification centers to re-stablish themselves, a process that may take up to 2 to 3ears. For more advanced osteonecrosis and collapse of theemoral head with severe functional impairment, surgicalptions include debridement of necrotic bone, valgus osteot-my, and arthroplasty in carefully selected cases.

Determining the prognosis is important at the time ofresentation because more than 50% of patients with Legg-alve Perthes disease do not require surgical treatment. Thearlier the stage of the disease at presentation, the better therognosis. Although early osteoarthritis develops in someatients, many are able to function relatively well until theirfth or sixth decade of life.

.4 Educational Activity: Describe the classificationsystem that categorizes athletic events for athleteswith disabilities.

he classification system applied to competitions partici-ated in by athletes with various disabilities is analogous toeight classification systems used in sports like wrestling.he primary goals of the classification system are to enablethletes with disabilities to compete against peers with simi-ar impairments, and to fairly adjust competition results toccount for the range of functional abilities among thethletes.

Classification systems are sport specific, and each interna-ional sport federation is responsible for devising and imple-enting a classification system for its sport. The classificationrocess for the Paralympic Games is an ongoing, long-termrocess that is organized by the International Paralympicommittee (IPC). The IPC approves selected physicians and

herapists as official classifiers, and works with local organiz-ng committees to provide classification evaluation and pro-est review in accordance with the IPC guidelines. The IPCeeks physicians with an understanding of the interplay

etween impairment and function to serve as classifiers.

he IPC Classification Committee works closely with thePC Sports Science Committee to update classificationchemes as disabled sports medicine research yields newnformation about the intersection between impairment,daptive equipment and functional ability. Classificationonsists of 3 primary elements: status, classification eval-ation and protest.

Athletes may fall into 1 of 3 classification statuses: Para-ympic new status (PNS), Paralympic review status (PRS) andaralympic permanent status (PPS). The PNS category is forthletes who have never undergone an IPC approved classi-cation evaluation. These athletes must undergo a classifica-ion evaluation before they can participate in accreditedompetition. The PRS category is a temporary designation forthletes who require reevaluation or technical review, or haveot fully completed an approved classification evaluation.hese athletes may have changing or progressive conditions

hat require ongoing reevaluation of functional ability inrder to be fairly placed in competition. The PPS category isstatus designation for athletes who have completed an

PC-approved classification evaluation. Permanent status im-lies that the athlete’s functional ability will not change overime. If an athlete does not meet the minimum criterion forisability at the time of official classification, he/she is given anot eligible” (NOE) status and is not allowed to compete.ifferent types of classification systems are used for individ-al sports, team sports, timed sports and competition scoredy judges.

The classification evaluation itself has 3 components: aedical evaluation, a functional evaluation, and a technical

eview. In the medical evaluation, the classifiers review med-cal records and perform comprehensive musculoskeletalnd neurologic examinations. In the functional evaluation,he classifiers test the athlete’s performance in simulatedport-specific positions and activities. Athletes are obligatedo participate in the classification evaluation to the full extentf their ability. Misrepresentation of functional ability duringhe evaluation constitutes an ethics violation and is groundsor disqualification. In a technical review, classifiers observen athlete performing during training or competition tonsure that the athlete’s actual performance is commensurateith the classification category determined during the med-

cal and functional reviews. A technical review is held only forhose athletes whom the chief classifier determines requireurther observation to verify their sport class after the medicalnd functional evaluations are completed.

A protest of an athlete’s sport class may be lodged whenhe sport class that has been assigned to the athlete is inuestion. Protests may be referred to a Protest Committee orhe Board of Arbitration on Classification for review. Therotest process may result in a change in the athlete’s classi-cation status [12].

.5 Clinical Activity: Summarize the current recom-mendations for the evaluation and treatment of an

amenorrheic 16-year-old gymnast with shin pain.

Tftos[pci

cwiheuaoBLt

efirldr[t

mfefeOimnsa

mrcusfmBpBsh

te

fbpcCneemeocidtu

5

Ibpwre

pmoccs

ebupuh

rtral

tiwt[

S81PM&R Vol. 1, Iss. 3, Supplement 1, 2009

he female athlete triad (Triad) should be suspected in anyemale athlete who sustains a stress fracture. The 3 factors ofhe Triad (disordered eating, amenorrhea, osteoporosis) canccur in athletes of any age. The prevalence varies widely byport, but affects an average of 4.3% of elite female athletes13]. Risk factors include participation in endurance sports,articipation in athletic performances that have an aestheticomponent (eg, gymnastics), restricted caloric intake or eat-ng disorder, excessive exercise, and vegetarian diet.

The Triad’s pathophysiology is complex. The reducedaloric intake associated with the eating disorder combinedith high energy expenditures from excessive exercise results

n a catabolic state [13]. The negative energy balance causesypothalamic-pituitary-gonadal axis suppression and damp-ning of the pulsatile GnRH release [13,14]. Follicular stim-lating hormone (FSH) and luteinizing hormone (LH) levelsre reduced, resulting in decreased estrogen and progester-ne levels, and the development of amenorrhea [13,14].one mineral density decreases due to a lack of estrogen [14].ow estrogen also reduces endothelium-dependent vasodila-ion, leading to premature cardiovascular disease [15].

Ninety five percent of stress fractures occur in the lowerxtremities [16]. They are 1.5 to 3.5 times more common inemale athletes than male. These fractures occur when repet-tive microtrauma in the bone outpaces bone repair. Intrinsicisk factors include female gender, biomechanical factors (eg,eg length discrepancy, pes cavus, hyperpronation), and re-uced estrogen levels. The risk for stress fracture in amenor-heic athletes is 4.5 times higher than eumenorrheic athletes14]. Extrinsic risk factors including training intensity, dura-ion, and frequency; and footwear type.

The history for discovering the Triad should include infor-ation on eating behaviors, information on exercise duration,

requency and intensity; on body image, fear of weight gain, selfsteem, previous injury history, and menstrual history. Patientsrequently report cold intolerance and hair loss [13]. Physicalxamination should include height, weight, and vital signs.rthostatic hypotension and bradycardia are frequently found

n Triad patients. Their skin may appear flaky and dry, and theyay have alopecia and lanugo. Their body habitus should beoted. Biomechanical factors that predispose to stress fracturehould be assessed. The area of their pain should be palpatednd the joint above and below it examined [13].

Radiologic, laboratory, and electrocardiographic studiesay be useful. Initially, stress fractures are not demonstrable

adiographically. Bone scans are highly sensitive but nonspe-ific for acute stress fractures, and they display increasedptake in all 3 phases within 3 days of injury. The third bonecan phase may take months to years for normalizationollowing stress fracture. An MRI is also very sensitive, and is

ore specific than bone scan for stress fracture [13,16].ecause of its high osseous resolution, computed tomogra-hy is occasionally used to detect suspected stress fracture.one mineral density assessment via dual-energy x-ray ab-orptiometry (DEXA) scan is indicated for athletes with a

istory of stress fractures or fractures following minor n

rauma, history of hypoestrogenism, or disordered eating orating disorders for 6 months or longer [13].

Treatment of athletes with the Triad is multifaceted andrequently requires a multidisciplinary team. The athlete shoulde referred to her gynecologist or primary care physician for aelvic examination and amenorrhea evaluation. If secondaryauses of osteoporosis other than the Triad are considered (eg,ushing syndrome), further evaluation can be performed. Autritionist and psychologist should be consulted to assist inating disorder management. The athlete should decrease herxercise intensity and increase her caloric intake to the point thatetabolic homeostasis can be achieved. The athlete should

nsure daily ingestion of 1000-1300 mg of calcium, 400-800 IUf vitamin D, and 60-90 �g of vitamin K [13]. The use of oralontraceptive pills and hormone replacement in this populations controversial and does not appear to improve bone mineralensity [13,16]. Bisphosphonates should not be used for thereatment of osteoporosis in the young population due to theirnproven efficacy, and their potential teratogenicity [13].

.6 Clinical Activity: Design an exercise program for a28-year-old pregnant woman.

t is well known that exercise provides significant healthenefits. However, there has been concern regarding theotential for adverse maternal and/or fetal outcomes inomen who exercise during pregnancy. This section will

eview the risks, benefits, and current recommendations forxercise in pregnancy.

Physiologic adaptations to pregnancy include increases inlasma volume, red blood cell mass, heart rate (15-20 beats/inute), stroke volume, and cardiac output [17]. A majority

f these changes occur by 12 weeks of gestation [17]. Exer-ising women experience 40% and 20% greater increases inardiac output and blood volume, respectively, than theiredentary counterparts [17].

During exercise, uterine blood flow decreases [17]. How-ver, the maternal uterus compensates for this by shuntinglood from the myometrium to the placenta, thus increasingteroplacental tissue oxygen extraction [17]. Fetal erythro-oietin levels do not increase in response to sustained stren-ous maternal exercise, which supports the notion that fetalypoxia does not occur during maternal exercise [17].

Maternal hyperthermia has been associated with fetal neu-al tube defects, leading to fears that exercise related hyper-hermia may be teratogenic [17]. However, the hyperthermicesponse to exercise is dampened in pregnant women due ton increased blood volume, earlier initiation of sweating, andarger body habitus [17].

Exercise during pregnancy has not been shown to increasehe incidence of miscarriages or pre-term labor [17]. Highntensity third trimester exercise leads to low birth weights,hile initiating a new exercise program in poorly condi-

ioned women results in higher than normal birth weights17]. Physically active pregnant women have improved fit-

ess and sense of well-being, fewer adverse symptoms of

pd

(vwopltmaihfirswescd

apc

R

*

*

*

T

TD

S82 Willick et al SPECIAL POPULATIONS

regnancy, and a 50% and 40% reduction in gestationaliabetes mellitus and preeclampsia, respectively [18,19].

Listed contraindications to exercise during pregnancyTable 1), and low and high-risk exercises (Table 2) providealuable information for the pregnant woman. For pregnantomen in whom exercise is not contraindicated, a few rec-mmendations can be made. Initiation of a new exerciserogram should begin with a short duration (15 minutes),

ow intensity (55%-65% of maximum heart rate) activity 3imes weekly. Low impact (walking) or non-impact (swim-ing) exercises are preferable. While the duration, frequency

nd intensity of exercise can be gradually increased, thentensity should not exceed 85% of the mother’s maximumeart rate [18]. Supine exercise should be avoided after therst trimester. Exercises to strengthen the pelvic floor areecommended. Only light resistance should be used duringtrengthening exercises. Proper breathing technique duringeight lifting entails inhalation and exhalation during the

ccentric and concentric phases of muscle contraction, re-pectively. Fluid and caloric intake should be monitoredlosely because of the additional nutritional requirementsuring pregnancy.

Exercise should be discontinued if the athlete experiencesny of the following: dyspnea, dizziness, nausea, weakness,ain, generalized edema, decreased fetal activity, uterineontraction, vaginal bleeding or fluid leakage.

able 1. Contraindications to Exercise During Pregnancy

1. Hemodynamically significant heart disease or anemia2. Cervical incompetence3. Uterine bleeding4. Ruptured membranes5. Fetal distress6. More than 1 previous miscarriage or premature labor7. Uncontrolled hypertension or renal disease

able 2. Exercises of Low and High Riskuring Pregnancy

Low risk exercisesWalking, swimming, low-impact aerobics, light weight liftingHigh risk exercisesMountain biking, heavy weight lifting, contact sports, scuba

*diving below 10m, skiing, ice skating

EFERENCES*1. Vad V, Hong HM, Zazzali M, Agi N, Basrai D. Exercise recommenda-

tions in athletes with early osteoarthritis of the knee. Sports Med2002;32:729-739.

2. Zhang W, Jones A, Doherty M. Does paracetamol (acetaminophen)reduce the pain of osteoarthritis? A meta-analysis of randomizedcontrolled trials. Ann Rheum Dis 2004;63:901-907.

3. Bellamy N, Campbell J, Robinson V, Gee T, Bourne R, Wells G.Intraarticular corticosteroid for treatment of osteoarthritis of the knee.Cochrane Database Syst Rev 2006;(2):CD005328.

4. Fletcher GF, Mills WC, Taylor WC. Update on exercise stress testing.Am Fam Physician 2006;74:1749-1754.

5. Lear SA, Brozic A, Myers JN, Ignaszewski A. Exercise stress testing: anoverview of current guidelines. Sports Med 1999;27:285-312.

*6. Gibbons RJ, Balady GJ, Bricker JT, Chaitman BR, Fletcher GF,Froelicher VF, et.al. ACC/AHA 2002 guideline update for exercisetesting. Summary of the report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Cir-culation 2002;106:1883-1892.

7. Junnila JL, Runkle GP. Coronary artery disease screening, treatment,and follow-up. Prim Care 2006;33:863-885.

8. Darrow MD. Ordering and understanding the exercise stress test. AmFam Physician 1999;59:401-414.

9. Gough-Palmer A, McHugh K. Investigating hip pain in a well child.BMJ 2007;334:1216-1217.

10. Aronsson DD, Loder RT, Breur GJ, Weinstein SL. Slipped capitalfemoral epiphysis: current concepts. J Am Acad Orthop Surg 2006;12:666-679.

11. Poul J. Diagnosis of Legg-Calve-Perthes disease. Orthop TraumatolRehabil 2004;6:604-606.

12. International Paralympic Committee. Classification: general informa-tion. November 2007. http://www.paralympic.org/release/Main_Sections_Menu/Classification/. Accessed September 4, 2008.

13. Nattiv A, Loucks AB, Manore MM, Sanborn CF, Sundgot-Borgen J,Warren MP. The female athlete triad. American College of SportsMedicine position stand. Med Sci Sports Exerc 2008;39:1867-1882.

14. Lo BP, Hebert C, McClean A. The female athlete triad–no pain, nogain? Clin Pediatr 2003;42:573-580.

15. Hoch AZ, Lal S, Jurva JW, Gutterman DD. The female athlete triadand cardiovascular dysfunction. Phys Med Rehabil Clin N Am 2007;18:385-400.

16. Feingold D, Hame SL. Female athlete triad and stress fractures.Orthop Clin N Am 2006;37:575-583.

17. Morris S, Johnson NR. Exercise during pregnancy: a critical appraisalof the literature. J Reprod Med 2005;50:181-188.

18. Kramer M, McDonald SW. Aerobic exercise for women during preg-nancy. Cochrane Database Syst Rev 2006;(3):CD000180.

19. Dempsey J, Butler CL, Williams MA. No need for a pregnant pause:physical activity may reduce the occurrence of gestational diabetesmellitus and preeclampsia. Exerc Sport Sci Rev 2005;33:141-149.

Indicates key references.