Low bone density is an etiologic factor for stress fractures in athletes

Eating disorders

Anorexia nervosa, bulimia nervosa, and eating disorders not otherwise specified remain a significant cause of morbidity and mortality in girls and young women. Management of eating disorders typically requires a multidisciplinary team approach, often spear-headed by the clinician initially detecting the illness. This article addresses the definitions and prevalence of eating disorders, tips on recognition and management of medical complications, and reproductive health concerns for these young women. Issues surrounding care of the patient with the female athlete triad, or amenorrhea, osteopenia, and eating disorders, are also discussed.

Disordered eating, menstrual irregularity, and bone mineral density in female runners

PURPOSE

To examine the relationships between disordered eating, menstrual irregularity, and low bone mineral density (BMD) in young female runners.

METHODS

Subjects were 91 competitive female distance runners aged 18-26 yr. Disordered eating was measured by the Eating Disorder Inventory (EDI). Menstrual irregularity was defined as oligo/amenorrhea (0-9 menses per year). BMD was measured by dual x-ray absorptiometry.

RESULTS

An elevated score on the EDI (highest quartile) was associated with oligo/amenorrhea, after adjusting for percent body fat, age, miles run per week, age at menarche, and dietary fat, (OR [95% CI]: 4.6 [1.1-18.6]). Oligo/amenorrheic runners had lower BMD than eumenorrheic runners at the spine (-5%), hip (-6%), and whole body (-3%), even after accounting for weight, percent body fat, EDI score, and age at menarche. Eumenorrheic runners with elevated EDI scores had lower BMD than eumenorrheic runners with normal EDI scores at the spine (-11%), with trends at the hip (-5%), and whole body (-5%), after adjusting for differences in weight and percent body fat. Runners with both an elevated EDI score and oligo/amenorrhea had no further reduction in BMD than runners with only one of these risk factors.

CONCLUSION

In young competitive female distance runners, (i) disordered eating is strongly related to menstrual irregularity, (ii) menstrual irregularity is associated with low BMD, and (iii) disordered eating is associated with low BMD in the absence of menstrual irregularity.

MR imaging of sports-related hip disorders

Hip arthroscopy is being used increasingly for the diagnosis and treatment of hip disorders. MR imaging performed with appropriate technical considerations may aid not only in preoperative planning but in the appropriate selection of patients, which tends to lead to better postoperative results. Although the painful hip is imaged most commonly by radiography, MR imaging is considered the next imaging test of choice for evaluation of most common hip abnormalities in athletes, including labral injuries, ligament injuries, osteochondral injuries, fractures, bursitis, and musculotendinous injuries. MR arthrography can be a particularly useful technique for dedicated assessment of hip joint internal derangements.

Sacral stress fractures: tracking down nonspecific pain in distance runners

Sacral stress fractures are an underrecognized cause of low-back and gluteal pain in distance runners. The combination of low bone density and increased activity blurs the boundary between fatigue and insufficiency fractures in many runners. MRI is the preferred radiologic technique because of its ability to localize the site of injury and rule out tumors, disk disease, or sacroiliitis. By identifying the condition early, clinicians contribute to a favorable outcome and help most athletes return to full activity in 12 to 14 weeks.

Repetition of an unusual stress fracture in an anorexic man: a case report

Stress fractures of the fibula commonly occur distally in runners, whereas stress fractures of the proximal fibula are uncommon and typically occur in jumpers. Furthermore, it is rare for a stress fracture to be repeated in the same bone. We report a case of a repeated stress fracture of the proximal fibula in a male runner with abnormal gait that primarily involved excessive pronation. Unusual risk factors in this case were anorexia nervosa and use of an inhaled corticosteroid. The patient was treated conservatively, and healing of the fracture was completed at 12 weeks.

Female athlete triad

OBJECTIVE

To describe the components of female athlete triad, the proposed mechanisms that may relate to its causation, and some screening and treatment options that may be used by the clinician who encounters this clinical entity in patients.

DATA SOURCES

A qualitative review of the literature was performed.

RESULTS

This article provides the clinician with current information relevant to understanding and recognizing female athlete triad in at-risk patients. The components of the triad-amenorrhea, disordered eating, and osteoporosis-are interrelated in multifactorial etiology, pathogenesis, and consequences. Proposed causal factors include inadequate nutrition, menstrual status, training intensity and frequency, body size and composition, and psychological and physiological stress. There should be a high index of suspicion in all females athletes for the presence of and/or increased risk for female athlete triad. An increased awareness of the existence of the problem and its presenting signs and symptoms is the key to screening for this syndrome. The most efficacious treatment lies in its prevention.

CONCLUSIONS

Female athlete triad is an interrelated, multifactorial syndrome comprised of disordered eating, amenorrhea, and osteoporosis. It is a common entity among female athletes. Prevention, early detection, and early treatment are absolutely essential to maintain the athletes health into maturity and to prevent the serious consequences of this triad. The long-term effects of some triad components are still unknown.

Bone mineral density in triathletes over a competitive season

There is evidence from previous cross-sectional studies that high volumes of certain sports, including running, swimming and cycling, may have a negative impact on bone mineral density. The aim of the present study was to evaluate prospectively the effects of high athletic training in individuals who engage in high volumes of all three of these activities (triathletes). Bone mineral density for the total body, arms and legs was determined by dual-energy X-ray absorptiometry in 21 competitive triathletes (9 men, 12 women) at the beginning of the training season and 24 weeks later. Age, body mass index, calcium intake and training volume were also recorded to examine potential mediators of bone mineral density change. Men had greater bone mineral density at all sites than women. No significant changes were observed over the 24 weeks for either total body or leg bone mineral density. Bone mineral density in both arms increased by approximately 2% in men (P < 0.03), but no change was observed for women. Change in bone mineral density at all sites was unrelated to age, body mass index, calcium intake and training volume. The results suggest that adverse changes in bone mineral density do not occur over the course of 6 months of training in competitive triathletes.

Bone density in competitive figure skaters

OBJECTIVES

To compare the bone mineral density (BMD) of competitive female teenage figure skaters with a history of fracture with the BMD of skaters without fracture and to compare each group to age-matched, nonathletic controls.

DESIGN

Retrospective age-matched cohort.

SETTING

Tertiary care medical center and 3 local skating clubs.

PARTICIPANTS

Thirty-six adolescent female competitive skaters (10 with fracture, 26 without fracture) to 22 age-matched controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

BMD was estimated by quantitative ultrasound.

RESULTS

Skaters who had suffered stress fractures had BMD values comparable with those of healthy nonathletic controls. However, skaters who had not suffered stress fractures had calcaneal BMD values 15% to 24% greater than either the controls or skaters with fractures. Among the skaters without fracture, there was a 14% to 19% higher calcaneal BMD in skaters who executed triple jumps relative to skaters who performed only double jumps. Furthermore, there was 7% to 11% greater BMD in the landing foot of the skaters relative to the takeoff foot.

CONCLUSIONS

Stress fractures in adolescent skaters are not caused by low bone mass but may result from excessive forces placed on a normal skeleton. Our findings also support the hypothesis that higher peak forces are applied to the landing foot relative to the takeoff foot.

Common athletic injuries in adolescent girls

Teenaged girls constitute the fastest growing segment of children and adolescents participating in organized athletics. Adolescent girls appear to have similar injury rates as boys in comparable activities but different injury patterns. To properly diagnose and manage athletic injuries in adolescent girls, pediatric health care providers must be aware of these differences, especially as the literature and their knowledge base may be skewed to the traditional predominance of males in sport. This review identifies athletic injuries that are unique to or especially common in adolescent girls, including apophyseal injuries; breast and pelvic injuries; scoliosis and spondylolysis; multidirectional shoulder instability and "gymnast's wrist"; anterior cruciate ligament injuries and patellofemoral pain syndrome; chronic exertional lower-leg compartment syndrome, ankle sprains, and reflex sympathetic dystrophy; and stress fractures. It also briefly discusses possible risk factors for these injuries, emphasizing the female athlete triad.

Development of a medical nutrition therapy protocol for female collegiate athletes

Nutrition intervention can improve athletic performance and reduce the risk of nutrition related problems in women athletes. The current healthcare environment demands that dietitians document the outcomes of the medical nutrition therapy (MNT) they provide. This requires the development and validation of MNT protocols so that outcomes can be documented and compared in similar populations across multiple settings. The purpose of this project was to develop a sports nutrition management MNT protocol for collegiate women athletes. A registered dietitian currently working with collegiate women athletes collaborated with four dietitians from the community to develop an MNT protocol. Further testing and validation using this MNT protocol will help dietitians document the outcomes of their interventions in this population.

Risk factors for recurrent stress fractures in athletes

Our aim was to identify factors predisposing athletes to multiple stress fractures, with the emphasis on biomechanical factors. Our hypothesis was that certain anatomic factors of the ankle are associated with risk of multiple stress fractures of the lower extremities in athletes. Thirty-one athletes (19 men and 12 women) with at least three separate stress fractures each, and a control group of 15 athletes without fractures completed a questionnaire focusing on putative risk factors for stress fractures, such as nutrition, training history, and hormonal history in women. Bone mineral density was measured by dual-energy x-ray absorptiometry in the lumbar spine and proximal femur. Biomechanical features such as foot structure, pronation and supination of the ankle, dorsiflexion of the ankle, forefoot varus and valgus, leg-length inequality, range of hip rotation, simple and choice reaction times, and balance in standing were measured. There was an average of 3.7 (range, 3 to 6) fractures in each athlete, totaling 114 fractures. The fracture site was the tibia or fibula in 70% of the fractures in men and the foot and ankle in 50% of the fractures in women. Most of the patients were runners (61%); the mean weekly running mileage was 117 km. Biomechanical factors associated with multiple stress fractures were high longitudinal arch of the foot, leg-length inequality, and excessive forefoot varus. Nearly half of the female patients (40%) reported menstrual irregularities. Runners with high weekly training mileage were found to be at risk of recurrent stress fractures of the lower extremities.

Femoral neck stress fractures and metabolic bone disease

OBJECTIVE

To determine whether metabolic bone disease plays a role in the cause of femoral neck stress fractures.

STUDY DESIGN

Twenty-three patients with femoral neck stress fractures were enrolled prospectively in the study. Examination included computed tomography bone densitometry, trace mineral analysis, and histomorphometric analysis of the iliac crest in thirteen patients who underwent surgical treatment of their stress fractures. A control group of fifteen patients undergoing iliac crest bone grafting for scaphoid nonunions underwent similar examinations.

SETTING

Tertiary military medical center.

RESULTS

Patients with femoral neck stress fractures had lower bone mineral density than did control patients (p = 0.010), but no trace mineral deficiencies or consistent histomorphometric differences were noted.

CONCLUSIONS

Bone mineral density is decreased in patients with femoral neck stress fractures. Despite observations of decreased bone mineral density in the stress fracture group, osteoporosis, as determined by histomorphometry, is not a consistent finding.

Flexural wave propagation velocity and bone mineral density in females with and without tibial bone stress injuries

STUDY DESIGN

Case-control nonexperimental design.

OBJECTIVES

To compare flexural wave propagation velocity (FWPV) and tibial bone mineral density (BMD) in women with and without tibial bone stress injuries (BSIs).

BACKGROUND

Physical therapists, particularly in military and sports medicine settings, routinely diagnose and manage stress fractures or bone stress injuries. Improved methods of preparticipation quantification of tibial strength may provide markers of BSI risk and thus potentially reduce morbidity.

METHODS AND MEASURES

Bone mineral density, FWPV, bone geometry, and historical variables were collected from 14 subjects diagnosed with tibial BSIs and 14 age-matched controls; all 28 were undergoing military training.

RESULTS

No difference was found between groups in FWPV and tibial BMD when analyzed with t tests (post hoc power = 0.89 and 0.81, respectively). Furthermore, no difference was found in tibial length, tibial width, femoral neck BMD, and lumbar spine BMD among the groups. There were no differences between the 2 groups in smoking history, birth control pill use, and onset of menarche. Finally, sensitivity and positive likelihood ratios for FWPV (0.14 and 0.63), tibial BMD (0.0 and 0.0), and lumbar BMD (0.18 and 2.0) were low, while specificity was high (0.77, 0.93, and 0.91, respectively).

CONCLUSION

Current bone analysis devices and methods may not be sensitive enough to detect differences in tibial material and structure; local stresses on bone may be more important in the development of BSIs than the overall structural stiffness.

Bone density issues in the adolescent gynecology patient

Because adolescence is a critical period for acquisition of peak bone mass, adolescent gynecology clinicians can play an important role in promoting and reinforcing skeletal health. Efforts should be focused on maximizing nutrition, exercise, and a normal sex steroid status during these formative years. Close attention should also be given to factors that jeopardize the attainment of peak bone mass: amenorrhea, malnutrition (e.g., anorexia nervosa), use of medications with deleterious effects on bone, and underlying medical conditions that may predispose a young woman to early bone loss. This review places special emphasis on a patient commonly seen in the adolescent and gynecology practice, the female athlete.

Stress fractures and bone health in track and field athletes

The effect of exercise on bone health has received much attention in recent years. The problems of the female athlete triad: disordered eating, amenorrhea and osteoporosis have helped us to better understand and appreciate the important interaction of mechanical, hormonal, nutritional as well as genetic factors on bone health in the young female athlete. The relatively high stress fracture incidence of young track and field athletes can be quite disabling for the athlete's present and future running career. A number of risk factors including low bone mineral density (BMD), menstrual irregularities, dietary factors and prior history of stress fractures have been associated with an increased risk for stress fractures in the female athlete. Few studies have found risk factors for stress fractures in the male athlete. Female gender has been found to be a risk factor for stress fractures in the military population, but this finding is less apparent in athlete studies. Caucasians have been found to have a higher risk for stress fractures than African-American military recruits, but there is very limited data assessing stress fracture risk in athletes of varying ethnicity. Prevention of stress injury to bone involves maximizing peak bone mass in the pediatric and young adult age groups. Maintaining adequate calcium nutrition, caloric intake as well as hormonal and energy balance are important preventive measures, as are ensuring appropriate amounts of weight bearing exercise for optimizing bone health and preventing fractures. More research is needed to determine factors leading to improvements in bone density and fracture reduction in athletes at risk.

Use of hormone replacement therapy to reduce the risk of osteopenia in adolescent girls with anorexia nervosa

PURPOSE

To assess how commonly hormone replacement therapy (HRT) and other measures are prescribed for the treatment of osteopenia in children and adolescents with anorexia nervosa (AN).

METHODS

A self-administered questionnaire was distributed and completed by allopathic and osteopathic physician members of the Society for Adolescent Medicine at its 1998 annual meeting. The questionnaire was also mailed and E-mailed between March 1998 and February 1999. Descriptive statistics included percentages and measures of central tendency.

RESULTS

The questionnaire was completed by 394 of the 1029 physicians surveyed (38.3%). Of the 268 respondents who treated patients with AN under the age of 18 years, 77.6% prescribed HRT. The decision to prescribe HRT was influenced by patient's age but not by bone mineral status. Among those who prescribed HRT, additional therapies included increased caloric intake (89.4%), weight gain (82.2%), increased calcium intake (84.1%), a change in exercise patterns (59.1%), and vitamin D supplementation (37.0%). Only 59 (22.0%) did not use HRT as a treatment modality. One-third of nonprescribers cited the lack of evidence of efficacy of HRT in preventing osteopenia. More recent medical graduates were less likely to prescribe HRT.

CONCLUSIONS

This survey suggests that practitioners caring for adolescent females with AN commonly prescribe HRT for the treatment of osteopenia despite the paucity of evidence demonstrating that it effectively prevents or reverses bone loss associated with this disorder.

Stress fractures in women

Stress fractures are common overuse injuries, reported more frequently in female athletes than in male athletes. The clinician should have a high index of suspicion for this injury whether an athlete presents with complaints of acute pain and disability or insidious onset of pain that is aggravated by activity and relieved by rest. Radiographs, bone scans, CT scans, and MR imaging may all be useful in confirming the diagnosis. Conservative treatment is usually successful, although one must be especially vigilant in treating a stress fracture prone to complications. Identifying risk factors for susceptibility to stress fracture development may help to avoid recurrence of the injury. More research is needed to determine cause versus association of these various risk factors in relationship to stress injury to bone.

Stress fractures in the Israeli defense forces from 1995 to 1996

This study, encompassing 2591 Israeli soldiers, characterized Israeli soldiers with stress fractures to profile individuals who are prone to experience stress fractures: 318 with clinically and scintigraphically proven high grade stress fractures; 237 soldiers with symptoms but with normal scintigraphy; and 2036 soldiers with no symptoms. Soldiers with high grade stress fractures weighed less (68.4 +/- 7.9 kg versus 70.5 +/- 12.4 kg), smoked less, and reported fewer previous stress fractures, had fewer reports of stress fractures in their family histories, and had fewer incidences of bone diseases than did control subjects. Serum levels of bone specific alkaline phosphatase and osteocalcin were elevated in patients with high grade stress fractures compared with control subjects with no symptoms: 37.6 versus 26.2 units/L, and 10.8 versus 8.8 ng/mL, respectively. Levels of 25-hydroxy vitamin D were lower in patients with high grade stress fractures (25.3 ng/mL) than in control subjects (29.8 ng/mL). This study revealed that several parameters can distinguish soldiers with high grade stress fractures, but their predictive value and precise pathogenetic role remain unclear.

The female athlete

Over the past 30 years, the number of women participating in organized sports has grown dramatically. Several forms of menstrual irregularities have been described in the female athlete: primary and secondary amenorrhoea, oligomenorrhoea, short luteal phases and anovulation. The incidence of menstrual irregularities is much higher in activities where a thin body is required for better performance. The hormonal pattern seen in these athletes is a hypothalamic amenorrhoea profile. There appears to be a decrease in gonadotrophin-releasing hormone (GnRH) pulses from the hypothalamus, which in turn decreases the pulsatile secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and shuts down stimulation of ovary. Recently, another type of amenorrhoea has been described in swimmers which is characterized by mild hyperandrogenism. Athletes with low weight are at risk of developing the female athletic triad, which includes amenorrhoea, osteoporosis and disordered eating. Athletes with this triad are susceptible to stress fractures. Other issues include the pregnant athlete. Intensive exercise during pregnancy can cause bradycardia. Safe limits of aerobic exercise in pregnancy depend on previous exercise habits. Infertility, which may develop with exercise, is probably reversible with reduction of exercise or weight gain. High impact sports activities may produce urinary incontinence. Oestrogen replacement therapy is often prescribed in amenorrhoeic athletes, but bone loss may not be completely reversible.

Stress fractures and the female athlete

Stress injury to bone is the result of a temporary disturbance in the equilibrium between bone resorption and bone regeneration. Knowledge of the pathophysiology of bone in health and disease currently encompasses an interactive mode that includes biomechanical, hormonal, nutritional, and genetic factors. The current study will review possible etiologic theories for stress injuries to bone with a special emphasis on gender-related factors. Females may be more at risk for a stress injury to bone because of their unique hormonal environment, and other anatomic and gender factors.

The relation between stress fractures and bone mineral density: evidence from active-duty Army women

OBJECTIVE

To determine if bone mineral density (BMD) is associated with the probability of stress fractures in premenopausal women.

DESIGN

Case-control study.

SETTING

Large Army post, Fort Lewis, WA.

PARTICIPANTS

Twenty-seven active duty Army women with documented stress fractures within the last 2 years and 158 female controls.

METHODS AND MAIN RESULTS

All subjects were examined and interviewed. BMD of the femoral neck and posteroanterior lumbar spine (L2-L4) was measured using dual energy X-ray absorptiometry. Univariate comparisons revealed no significant differences in BMD of the femoral neck or lumbar spine between groups. Women with stress fractures had a significantly higher exercise intensity (428 vs 292 minutes per week, p<.05) and were more likely to be entry-level enlisted soldiers (63% vs. 44%, p<.05) than those without stress fractures. Multivariate analyses revealed a strong negative association between femoral neck BMD and the probability of stress fractures (lower BMD, higher risk). Exercise intensity and body mass index had a significant positive effect on BMD of the femoral neck and lumbar spine, yet both were associated with an increased probability of stress fractures.

CONCLUSIONS

Femoral neck BMD was significantly associated with the probability of stress fractures. Optimal training programs should balance the beneficial indirect effect of increased exercise (through increased BMD) with its detrimental direct effect on stress fractures.

Physical activity, diet and skeletal health

Diet and physical exercise concur in the determination of skeletal mass at the end of adolescence and in the conservation of it during adult life. The functional demand imposed on bone is a major determinant of its structural characteristics. Stress applied to a skeletal segment affects the geometry of the bone, the microarchitecture and the composition of the matrix. The stimulatory effect occurs when the skeleton is subjected to strains exceeding habitual skeletal loads, and the intensity of load is more important than the duration of the stimulus. Physical activity leads to greater bone density in children and adolescents and, to a minor extent, in adults. Weight bearing activities, such as walking, have a greater effect than non weight bearing activities, such as cycling and swimming. Reduction of loads as in bed resting or in space flights leads to bone loss. Intense training may cause damage, promptly repaired, as in stress fractures observed in army recruits. Female athletes may experience oligo-amenorrhea, though they still have a positive bone balance. There is an important interaction between the mechanical demands and the availability of nutrients to manufacture bone tissue. The increase in bone density in post-menopausal women is positively related to calcium intake when calcium supplementation is accompanied by exercise. When mechanical demands are low, such as during immobilisation, the intestinal calcium absorption is reduced. Calcium intake should also be analysed in the light of other dietary factors affecting the balance between absorption and excretion, and in combination with a number of other minerals, trace elements and bioactive substances with an impact on bone metabolism.

Risk factors for stress fractures

Preventing stress fractures requires knowledge of the risk factors that predispose to this injury. The aetiology of stress fractures is multifactorial, but methodological limitations and expediency often lead to research study designs that evaluate individual risk factors. Intrinsic risk factors include mechanical factors such as bone density, skeletal alignment and body size and composition, physiological factors such as bone turnover rate, flexibility, and muscular strength and endurance, as well as hormonal and nutritional factors. Extrinsic risk factors include mechanical factors such as surface, footwear and external loading as well as physical training parameters. Psychological traits may also play a role in increasing stress fracture risk. Equally important to these types of analyses of individual risk factors is the integration of information to produce a composite picture of risk. The purpose of this paper is to critically appraise the existing literature by evaluating study design and quality, in order to provide a current synopsis of the known scientific information related to stress fracture risk factors. The literature is not fully complete with well conducted studies on this topic, but a great deal of information has accumulated over the past 20 years. Although stress fractures result from repeated loading, the exact contribution of training factors (volume, intensity, surface) has not been clearly established. From what we do know, menstrual disturbances, caloric restriction, lower bone density, muscle weakness and leg length differences are risk factors for stress fracture. Other time-honoured risk factors such as lower extremity alignment have not been shown to be causative even though anecdotal evidence indicates they are likely to play an important role in stress fracture pathogenesis.

The oral contraceptive pill: a revolution for sportswomen?

OBJECTIVES

To determine the effects of the oral contraceptive pill (OCP) on skeletal health, soft tissue injury, and performance in female athletes.

METHODS

A literature review was performed using literature retrieval methods to locate relevant studies.

RESULTS

Most female athletes primarily choose to use the OCP for contraceptive purposes, but cycle manipulation and control of premenstrual symptoms are secondary advantages of its use. The effect of the OCP on bone density in normally menstruating women is unclear, with some studies reporting no effect, others a positive effect, and some even a negative effect. The OCP is often prescribed for the treatment of menstrual disturbances in female athletes, and improvements in bone density may result. Whether the OCP influences the risk of stress fracture and soft tissue injuries is not clear from research to date. Effects of the OCP on performance are particularly relevant for elite sportswomen. Although a reduction in Vo2MAX has been reported in some studies, this may not necessarily translate to impaired performance in the field. Moreover, some studies claim that the OCP may well enhance performance by reducing premenstrual symptoms and menstrual blood loss. A fear of weight gain with the use of the OCP is not well founded, as population studies report no effect on weight, particularly with the lower dose pills currently available.

CONCLUSIONS

Overall, the advantages of the pill for sportswomen would appear to outweigh any potential disadvantages. Nevertheless, there is individual variation in response to the OCP and these should be taken into account and monitored in the clinical situation. Women should be counselled as to the range of potential benefits and disadvantages in order to make an informed decision based on individual circumstances.

Ground reaction forces, bone characteristics, and tibial stress fracture in male runners

PURPOSE

Tibial stress fracture is a common overuse running injury resulting from repetitive mechanical loading. This research project aimed to determine whether runners with a history of tibial stress fracture (TSF) differ in tibial bone geometry, tibial bone mass, and ground reaction force (GRF) parameters during running from those who have never sustained a stress fracture (NSF).

METHODS

Forty-six male running athletes (23 TSF; 23 NSF) ranging in age from 18 to 42 yr were recruited for this cross-sectional study. A force platform was used to measure selected GRF parameters (peak and time to peak for vertical impact force, vertical active force, and horizontal braking force) during running at 4.0 m x s(-1). Tibial bone geometry (cross-sectional dimensions and area) was calculated from a computerized tomography (CT) scan at the junction of the middle and distal thirds. Dual energy x-ray absorptiometry (DXA) provided measurements of tibial bone area, bone mineral content (BMC), and bone mineral density (BMD).

RESULTS

The TSF group had significantly smaller tibial cross-sectional area (P = 0.02) and DXA tibial bone area (P = 0.02), after adjusting for height and weight, than the NSF group. There were no significant differences between groups for GRF, tibial BMC, or tibial BMD.

CONCLUSION

These findings support the contention that bone geometry plays a role in stress fracture development and that male athletes with smaller bones in relation to body size are at greater risk for this bony injury.

Nutrition in the exercising elderly

When making nutrition recommendations to the exercising elderly population, four important areas should be taken into consideration: (1) the changing needs that occur with age; (2) the changing needs that occur with exercise; (3) the presence of any chronic illnesses or diseases; and (4) whether one is exercising for fitness, recreation, or competition. For the most part, these four areas have been researched separately, and recommendations for elderly athletes need to be synthesized from this information. The nutrients for which food consumption is often inadequate and has the largest impact on the exercising elderly population include vitamin B6, vitamin B12, calcium, and vitamin D. The exercising elderly population needs to be aware of their bodies changing needs with exercise and should focus on maintaining energy balance while selecting a wide variety of foods high in complex carbohydrates. When adequate dietary intakes cannot be obtained, supplementation with a multivitamin of no more than 100% of the RDA is recommended.

Menstrual irregularities associated with athletics and exercise

For women and girls, and dangers of excessively rigorous exercise regimens can include disturbances in reproductive function and a negative impact on bone density. Assisting female patients in finding a balance between the benefits and potential dangers of exercise is an important role for health professionals.

Overuse injuries in children and adolescents

With the growth of youth sports programs, overuse injuries in young people have become common. Making the diagnosis can be challenging, but often the real hurdles are in identifying the causes of injury. Growth-related factors require special considerations in injury management. A directed history assessing these and other causative factors and a systematic exam help formulate a comprehensive rehabilitation program. Recommendations for a successful return to activity and prevention of reinjury include avoiding heavy training loads and early sport-specific training, taking adequate rest periods, and ensuring proper supervision.

Exercise-induced loss of bone density in athletes

In athletes, the rarely identified malady of osteoporosis differs from other chronic effects of exercise. The most obvious difference is that hormonal imbalance leads to compensatory mechanisms that in turn lead to osteoporosis and increased incidence of fracture. Most research on this subject has dealt with women, because hormonal imbalances in women are easier to detect than those in men. Endurance athletes are known to have decreased levels of sex hormones, which can cause physiologic changes that lead to bone loss. This may result in relative osteoporosis despite the loading of the bone during exercise, which would normally increase bone mineral density. Premature osteoporosis may be irreversible, causing young athletes to become osteoporotic at an earlier age and have an increased risk of fracture later in life.

Meatless diets in female athletes: a red flag

Physically active adolescent girls and young women may eliminate meat from their diets to achieve or maintain low body weight. By doing so, they risk developing protein, iron, and zinc deficiencies. Further, meatless diets in this population may signal the possibility of amenorrhea and/or disordered eating, with the attendant risk of osteoporosis. Educating young women and their parents and coaches regarding the risks of a meatless diet and using the preparticipation exam to screen for these problems can promote preventive measures.

The female athlete triad

The opportunities for girls and women to play soccer has rapidly grown and gained acceptance in recent years. The benefits of involvement in soccer, both physically and psychologically, are overwhelmingly positive. Despite the benefits, girls and women involved in soccer are also at risk for medical problems as a result of their sports participation. Amenorrhea, disordered eating, and premature osteoporosis are entities known together as The Female Athlete Triad. The triad occurs in all sports and is associated with significant short- and long-term health consequences, and thus remains a concern for all involved in the care of the soccer athlete.

Decreased nitric oxide levels and bone turnover in amenorrheic athletes with spinal osteopenia

Amenorrheic athletes have been likened to postmenopausal women, with low estrogen levels and osteopenia. It has been suggested that estrogen exerts its antiresorptive actions on bone via a nitric oxide (NO)-dependent mechanism. This study investigated whether the mechanism of bone loss in amenorrheic athletes is similar to that of postmenopausal women with reduced NO levels and high bone turnover. Eleven amenorrheic athletes, 15 eumenorrheic athletes, and 10 sedentary controls were studied. Spine and hip bone mineral density was measured using dual-energy x-ray absorptiometry. Bone turnover was assessed by biochemical markers of formation (osteocalcin and bone-specific alkaline phosphatase) and resorption (deoxypyridinoline). NO metabolites were measured from 24-h urine samples using a chemiluminescence assay. Spine, but not hip, bone mineral density was reduced in the amenorrheic group, compared with the eumenorrheic (P = 0.0001) and control (P = 0.04) groups. Osteocalcin, bone-specific alkaline phosphatase, and deoxypyridinoline were similar in all groups. NO metabolites were lower in the amenorrheic group, compared with controls (P = 0.035), despite a higher dietary intake of nitrates. Unlike postmenopausal women, amenorrheic athletes do not have raised bone turnover but do have reduced NO metabolites and spinal osteopenia. The results show, however, that reduced NO production is a common denominator in both conditions and further support the importance of NO in estrogen-mediated protection of skeletal mass and strength.

Stress fractures

Stress fractures are being increasingly reported as a common cause of morbidity in both healthy populations and those with underlying diseases involving abnormal bone. An insight into the types and pathogenesis of stress fractures is necessary to considering the diagnosis, management and prevention of such conditions. The classification, aetiology and aspects of management are discussed.

Stress fractures in female army recruits: implications of bone density, calcium intake, and exercise

OBJECTIVE

To identify characteristics and factors associated with increased risk for stress fractures in military women.

DESIGN

Case-control study to retrospectively examine physical activity, prior calcium intake, and bone density as predictors of stress fractures.

SETTING

A military training installation which incorporates physical training for women.

SUBJECTS

Forty-nine female soldiers with confirmed stress fractures (cases) and 78 female soldiers with no orthopedic injuries (controls), aged 18 to 33 years.

MEASURES

Retrospective self-reports of habitual exercise, sports participation, and food intake; current height, weight, and body mass index (BMI); demographic variables (age, ethnicity, menstrual patterns, smoking habits); and bone density on radiologically defined stress fractures.

RESULTS

Cases and controls were similar in height, weight, and BMI. Measurements of bone density (g/cm2) at the trochanter (cases, 0.77+/-0.09; controls, 0.77+/-0.08); femoral neck (cases, 0.94+/-0.10; controls, 0.94+/-0.09); Ward's triangle (cases, 0.91+/-0.11; controls, 0.93+/-0.11); lumbar spine (cases, 1.21+/-0.12; controls, 1.24+/-0.10); and radius shaft (cases, 0.67+/-0.09; controls, 0.68+/-0.05) were not different between groups. Calcium intake was not different between groups (cases, 1154+/-751 mg/day; controls, 944+/-513 mg/day) and did not correlate with bone density (r=0.01 to -0.06 at four sites). Sports participation positively correlated with bone density in the hip (r=0.49). Leisure activity energy expenditure (kcal/day) tended toward association with lower stress fracture risk as expenditure level increased (p=0.06).

CONCLUSION

Stress fracture in female Army recruits was not correlated with bone density or calcium intake during adolescence, although a weak relationship to prior physical activity was observed.

Pharmacologic management of athletic amenorrhea

Amenorrhea is the absence of menses in reproductive-age women. The female athlete can frequently experience amenorrhea during athletic training. This article serves as an overview of the possible causes of amenorrhea. Its primary role, however, is to focus on both nonpharmacologic and pharmacologic treatment options for the female with athletic amenorrhea.

Insufficiency stress fractures of the foot and ankle in postmenopausal women

Eleven consecutive patients with 12 stress fractures of the foot or ankle were seen between October 1992 and July 1995. Charts were reviewed retrospectively for clinical information. The patients were all postmenopausal females. Average age was 62 years. Onset of symptoms was not associated with a specific episode of trauma. There were eight metatarsal fractures, three distal fibular fractures, and one fracture of the medial malleolus. Fractures were confirmed by radiographs, bone scan, or MRI in 9 of the 11 cases. Nonsurgical treatment utilizing rest, decreased activity, mechanical support, and analgesics resulted in successful union of the fracture except in one patient. Only four of the patients had been taking hormone or calcium supplements before injury. Just one patient had a prior bone density measurement, although four had a definite fracture previously and two had history suggestive of previous stress fracture. A careful history considering risk factors for osteoporosis should be obtained when an insufficiency type stress fracture is diagnosed. Bone density measurements should be considered for patients with this type of injury. Appropriate medical therapy directed at the treatment of the underlying osteoporosis in addition to orthopaedic management of the fracture constitute the treatment objectives. This dual approach may prevent subsequent injury.

Stress fractures in female athletes. Diagnosis, management and rehabilitation

Stress fractures are a common overuse injury among athletes. The incidence of stress fractures among females is higher in the military, but this difference is not as evident in the athletic population. The history of the patient with stress fracture is typically one of insidious onset of activity-related pain. If the patient continues to exercise, the pain may well become more severe or occur at an earlier stage of exercise. As well as obtaining a history of the patient's pain and its relation to exercise, it is important to determine the presence of predisposing factors. On physical examination, the most obvious feature is localised bony tenderness. Occasionally, redness, swelling or periosteal thickening may be present at the site of the stress fracture. The diagnosis of stress fracture is primarily a clinical one; however, if the diagnosis is uncertain, various imaging techniques can be used to confirm the diagnosis. In the majority of stress fractures, there is no obvious abnormality on plain radiograph. Although the triple phase bone radiograph is extremely sensitive, the fracture itself is not visualised and it may be difficult to precisely locate the site, especially in the foot. The radionuclide scan will detect evolving stress fractures at the stage of accelerated remodelling, so the findings must be closely correlated with the clinical picture. The characteristic bone scan appearance of a stress fracture is of a sharply marginated area of increased uptake, usually involving one cortex of the bone. Computerised tomography scanning is a helpful addition if the fracture needs to be visualised, or to distinguish between a stress reaction and stress fracture. Magnetic resonance imaging (MRI) is being used increasingly as the investigation of choice for stress fractures. The typical findings on MRI are of periosteal and marrow oedema, as well as fracture line. The basis of treatment of a stress fracture involves rest from the aggravating activity. Most stress fractures will heal in a straightforward manner, and return to sport occurs within 6 to 8 weeks. The rate of resumption of activity should be influenced by symptoms and physical findings. When free of pain, the aggravating activity can be resumed and slowly increased. It is important that the athlete with a stress fracture maintain fitness during this period of rehabilitation. The most commonly used methods are cycling, swimming, upper body weights and water running. There are a number of specific stress fractures that require additional treatment because of a tendency to develop delayed union or nonunion. These include stress fractures of the neck of the femur, anterior cortex of the tibia, navicular and second and fifth metatarsals. An essential component of the management of stress fractures, as with any overuse injury, involves identification of the factors that have contributed to the injury and, where possible, correction or modification of some of these factors to reduce the risk of the injury recurring. Stress fractures are more common in female athletes with menstrual disturbances. This may be due to the effect on bone density. The role of hormonal replacement in the management of these athletes is unclear at this stage.

Lactose intolerance associated with fractures of weight-bearing bones in Finnish women aged 38-57 years

Lactose intolerance (LI) often results in decreased calcium intake. To test if long-term low intake of calcium affects bone strength, we examined fracture risks related to LI in women aged 38-57 years. The 11,619 Finnish women aged 47-56 years who responded to the baseline postal inquiry of the Kuopio Osteoporosis Risk Factor and Prevention Study in 1989 formed the study population. In all, 896 women reported LI and 1299 women reported a fracture in 1980-1989. Current intake of dairy calcium was lower in women with LI (570 mg/d) than in the other women (850 mg/d) (p < 0.0001). The fracture risk in general was slightly elevated in women with LI compared with the other women, with an odds ratio (OR) (95% CI) of 1.33 (1.09-1.62). However, the fractures at the three most common sites (wrist, ankle, and rib) were not related to LI. In contrast, fractures at the tibia and metatarsal were strongly related to LI with ORs of 3.31 (1.51-7.24) and 2.84 (1.47-5.50), respectively. The adjusted OR for nonankle lower body fractures combined was 2.15 (1.53-3.04), whereas that for all upper body fractures combined was 1.15 (0.88-1.54). The 10 women with LI and a tibial or metatarsal fracture showed a 19% lower femoral BMD than all the other women in the densitometry subsample of 3222 women (p < 0.001). Long-term premenopausal calcium deficiency differentially affects bones with weight-bearing nonankle bones being at the greatest risk of suffering reduced strength.