Sudden cardiac arrest during marathons among young, middle-aged, and senior runners.

AIM: There is limited evidence showing a relationship with age in the incidence of sudden cardiac arrest during exercise, which can be lethal at times METHODS: To examine the incidence by age group in sudden cardiac arrest, we prospectively observed cases of sudden cardiac arrest in full marathons certified by the Japan Association of Athletics Federations held between April 2011 and March 2019. Sudden cardiac arrest was defined as collapse during or 1 h after the race requiring chest compressions or the use of an automatic electrical defibrillation. RESULTS: 4.1 million persons ran in 516 marathons. Of the participants, 78.6 % were men. By age group, 37.4 %, 34.7 %, 19.6 %, and 8.3 % belonged to the < 40 s, 40 s, 50 s, and ≥ 60 s groups, respectively. During the study period, 69 sudden cardiac arrests (1.7 per 100,000 participants, 95 % confidence interval [CI]: 1.3-2.1) were observed, of which 66 were men. The incidence per 100,000 runners of sudden cardiac arrest was 0.9 (95 % CI: 0.4, 1.4), 0.9 (95 % CI: 0.4, 1.4), 2.6 (95 % CI: 1.5, 3.8), and 5.5 (95 % CI: 2.9, 8.2) for those in their under 40 s, 40 s, 50 s, and over 60 s, respectively, with higher rates for older age groups. Compared to men, the cases of SCA among women were less common (only three cases), and the incidence did not differ by age group. CONCLUSIONS: Men, unlike women, had a higher incidence of sudden cardiac arrest during marathons according to age. Identification of this high-risk population could be important information in encouraging marathoners pre-participation self-screening.

Link Between Ferritin, Vitamin D, Performance, and Eating Attitudes in Female Athletes.

Iron and vitamin D deficiencies can affect athletes' health and performance. However, the epidemiology and associated risk factors remain unclear. Forty-three elite female athletics athletes (20.2 ± 1.9 years) were included. A survey regarding the training schedule and Eating Attitudes Test-26, body composition, bone mineral density, and serum 25-hydroxyvitamin D (25(OH)D) and ferritin levels were assessed. Mean serum 25(OH)D and ferritin levels were 25.2 ± 5.5 ng/mL and 29.0 ± 13.2 ng/mL, respectively, and 83.7% and 41.9 % of athletes had vitamin D and ferritin insufficiency, respectively. Serum 25(OH)D level was negatively correlated with the number of rest days per week (Coefficient, -6.19; 95% confidence interval [CI], -9.82--2.57; p = 0.002), and serum ferritin level was negatively correlated with body mass index (Coefficient, -3.87; 95% CI, -7.57--0.16; p = 0.041). Performance levels were positively correlated with serum vitamin D levels (Coefficients, 7.25; 95% CI, 0.25-14.25; p = 0.043) and negatively correlated with EAT-26 scores (Coefficient, -7.30; 95% CI, -12.61--1.98; p = 0.009) and body fat percentage (Coefficient, -13.26; 95% CI, -24.66--1.86; p = 0.025). Vitamin D and ferritin insufficiencies are prevalent among Japanese female athletics athletes. Serum vitamin D level was related to performance level.

Improvement of Jet Lag and Travel Fatigue Symptoms and Their Association with Prior International Travel Experience in Junior Athletes.

Jet lag and travel fatigue can occur after crossing multiple time zones in a short period of time, possibly affecting various aspects of an athlete's behavior. However, there are few studies regarding this issue, particularly considering junior athletes. This study aimed to investigate and quantify the symptoms of jet lag and travel fatigue and the factors impacting these conditions. A survey was completed by 41 Japanese junior athletes (21 men and 20 women), competing at an international game in Finland, to assess their performance, sleeping habits, digestion, fatigue, and jet lag on the first day of arrival and on the opening day of the competition. Although athletes awoke less often during sleep on the opening day of the competition compared with the first day, sleep time, ease of falling asleep, and sleep quality decreased significantly. Prior experience traveling abroad for international competitions was positively associated with improvements regarding ease of falling asleep (coefficient = 2.22, p = 0.01), quality of sleep (coefficient = 2.16, p = 0.02), and alertness after waking up (coefficient = 1.85, p = 0.05) by the opening day of the competition when compared with the results for athletes who had no such prior experiences. Junior athletes experience symptoms of jet lag and travel fatigue that may persist until the day of competition, and prior experience traveling abroad may help in alleviating their symptoms.

Muscle injuries in athletics during the 2020 Tokyo Olympic Games: differences between heats and finals.

BACKGROUND: The aim of this study was to analyze muscle injuries and their related risk factors during the Athletics events of the 2020 Tokyo Olympic Games including the differences in muscle injury rates between heats and finals. METHODS: We included and analyzed in this study muscle injuries diagnosed by either magnetic resonance imaging, ultrasound, or physical examinations by at least two physicians, from Athletics athletes participating at the 2020 Tokyo Olympic Games. Data from electronic medical records, including sex, nationality, event, and the round (heat vs. final) during which the muscle injury occurred and the air temperature in the stadium, measured every five minutes during the competition were extracted. RESULTS: Among the 1631 athletes who competed, a total of 36 athletes (20 males and 16 females) were diagnosed with a muscle injury during the 2020 Tokyo Olympic Games. Among them, 24 occurred during heats (1.47 per 100 athletes) and 12 during finals (2.20 per 100 athletes) (P=0.25). Logistic regression analysis revealed that the geographic region of athletes' origin was a factor associated with muscle injury, with the highest muscle injury rate being in athletes from Africa (odds ratio [OR]=4.74, 95% confidence interval [CI]) = 1.75 to 12.82) and North America (OR=3.02, 95%CI=1.27 to 7.20). For male athletes, competing in finals was a risk factor to sustain a muscle injury (OR=2.55, 95%CI=1.01 to 6.45). CONCLUSIONS: During the 2020 Olympic Games, muscle injury rate was higher in finals than in heats, reaching statistical significance in male athletes.

International study of physicians' opinion on physician-patient sex concordance when treating athletes.

BACKGROUND: The effect of physician-patient sex concordance in medicine has been reported in many studies. Whether physicians believe that the sex concordance between physician and athlete influences treatment has not been investigated. OBJECTIVE: To determine whether physicians believe that the sex concordance between physician and athlete influences treatment. DESIGN: Cross-sectional study. SETTING: Online survey. PARTICIPANTS: One thousand one hundred ninety-three sports medicine physicians in 51 countries. Participants were sports medicine physicians trained in orthopedics (n = 443 [37.1%]) and nonorthopedics (n = 750 [62.9%]). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Participants were asked to decide whether sex of the physician made them better suited to care for athletes of concordant or different sexes along with their personal background. RESULTS: Orthopedic sports medicine physicians agreed less than nonorthopedic sports medicine physicians regarding the statement "MALE sports medicine physicians are better suited than their female counterparts to care for MALE athletes" (odds ratio [OR] 0.56, 95% confidence interval [CI] 0.35-0.91, p = .02), and compared to sports medicine physicians based in Europe, those based in Asia agreed more to this statement (OR 7.91, 95% CI 4.60-13.60, p < .01). In addition, regarding the statement "FEMALE sports medicine physicians are better suited than their male counterparts to care for FEMALE athletes," compared to sports medicine physicians based in Europe, those based in Asia (OR 9.12, 95% CI 5.63-14.79, p < .01) and North America (OR 2.18, 95% CI 1.46-3.25, p < .01) agreed more and orthopedic sports medicine physicians agreed less than nonorthopedic sports medicine physicians (OR 0.61, 95% CI 0.39-0.93, p = .02) to this statement. CONCLUSIONS: Sports medicine physicians trained in orthopedics felt sex concordance was less important than physicians trained in other specialties. Asian sports medicine physicians believed sex concordance was more important compared to physicians in other regions.

Prevalence of anemia and iron deficiency and its association with body mass index in elite Japanese high school long-distance runners.

OBJECTIVES: Anemia is a common condition in long-distance runners (LDRs). Recently, not only iron deficiency (ID) but also energy deficiency has been considered as a risk factor for anemia in athletes but no evidence has yet been established. The aim of this study was to investigate the prevalence of anemia and ID and the influence of body mass index (BMI) on anemia in high-school LDRs. METHODS: The participants were 406 male and 235 female elite Japanese LDRs who competed in the All-Japan High-School Ekiden Championship 2019. They submitted their anthropometric data and results of a blood test within five days after the competition. The prevalence of anemia and ID and the influence of BMI on anemia were assessed retrospectively. RESULTS: Mean hemoglobin concentrations (Hb) were 14.8 ± 0.9 g/dl in males and 13.2 ± 0.9 g/dl in females. The prevalence of anemia (Hb < 14 g/dl in males and < 12 g/dl in females) was significantly higher in males (16.3%) than females (6.4%), but males also showed higher prevalence of non-iron deficiency anemia (NIDA) than females (11.6% and 3.0%, respectively). No significant gender difference was found in the prevalence of iron deficiency anemia (IDA) (4.7% in males and 3.4% in females). ID (serum ferritin level < 25 ng/ml) was significantly more prevalent in females (37.4%) than males (18.5%). A binary logistic regression analysis revealed that low BMI was a contributor to anemia in females (odds ratios: 0.577 (95% CI: 0.369-0.901), p = 0.012). CONCLUSION: In Japanese high-school LDRs, one in six males was anemic, but most males did not have ID. Conversely, one-third of females were diagnosed with ID. Lower BMI was identified as a risk for anemia in females, suggesting that leanness may also lead to anemia in females.

Awareness and Knowledge of Medical Issues Related to Female Athletes Among Track and Field Coaches.

Introduction: Little is known regarding medical knowledge pertaining to female athletes among track and field coaches and their interactions with female athletes regarding medical problems. Methods: Participants were track and field coaches (369 males and 43 females) with Japan Sport Association certification and they completed an anonymous survey on their knowledge of medical problems pertinent to female athletes including whether the coaches knew about the female athlete triad and relative energy deficiency in sports; their feelings about female athletes' use of contraceptive pills; whether they speak about menses with the female athletes; and whether they have a gynecologist for consultation regarding their medical problems. Results: Females coaches were significantly more likely to be aware of the triad (odds ratio (OR), 3.44; p = 0.003); to have access to a physician able to address the gynecological problems of female athletes (OR, 9.22; p < 0.001); and to talk to their female athletes about menses (OR, 2.30; p = 0.015) than their male counterparts. Coaches with more experience tended to be aware of the triad and relative energy deficiency in sports compared with those with ≤5 years of experience. Conclusion: Females coaches are aware of the triad, talk about menses with their female athletes, and have access to a physician who can address gynecological problems with compared to male counterparts. Educating all coaches on these problems is essential to provide adequate support to female athletes.

Controlling Behavior, Sex Bias and Coaching Success in Japanese Track and Field.

Coaching athletes is a complex and lengthy process. Recently, attention has been given to coaches over-controlling behavior toward the athletes' personal lives and possible sex bias, but the impact of these behaviors on coaching success is unclear. An anonymous survey was answered by 412 track and field coaches (male: 369; female: 43), comprising questions regarding controlling behaviors, sex bias, and personal background. A Chi-square test and logistic regression were performed to determine the factors related to the coach's characteristics and their success in coaching athletes (to national vs. non-national level). The results showed that controlling behaviors and sex-bias-related beliefs were present. The coaches who coached national-level athletes were more likely to be older, more experienced, and were national level athletes themselves. More national-level coaches reported controlling behaviors but fewer held sex bias beliefs than the non-national level coaches. However, the strength of these beliefs (scores for controlling behavior and sex bias) was not related to the coaching success.

An international study on attitudes and opinions regarding female sports medicine physicians during pregnancy and the postpartum period.

OBJECTIVES: Supporting female sports medicine physicians to simultaneously be mothers and pursue professional careers is crucial to maintain gender diversity in sports medicine physicians. The purpose of this study is to understand the attitudes toward female sports medicine physicians during pregnancy and postpartum. METHODS: An anonymous online survey was distributed to sports medicine physicians practicing in 51 different countries. They were asked how comfortable they felt with female sports medicine physicians working on the sidelines of sporting events during pregnancy, if the female sports medicine physicians were as productive as their male counterparts after giving birth, and how satisfied they were with the percentage of female sports medicine physicians in their country. Data were analyzed using the chi-square test, and multivariate logistic regression analysis was performed to identify independent variables. RESULTS: In total, 1193 physicians (380 [31.9%] female) were included for analysis. Physicians in Asia were the least comfortable with pregnant sports medicine physicians working on the sidelines and those in North America were the most comfortable (odds ratio = 0.28 and 2.51, 95% confidence interval 0.18-0.44 and 1.55-4.06, respectively). More experienced sports medicine physicians (odds ratio = 1.01, 95% confidence interval 1.00-1.03; p < 0.05) and divorced physicians (odds ratio = 0.33, 95% confidence interval 0.12-0.91; p < 0.05) were less comfortable with pregnant female sports medicine physicians working on sidelines, and those trained in orthopedics were less likely to agree that female sports medicine physicians were equally as productive as male counterparts postpartum (odds ratio = 0.29, 95% confidence interval 0.10-0.88; p < 0.05). Female physicians were less satisfied with the percentage of female sports medicine physicians in their country (odds ratio = 0.41, 95% confidence interval 0.27-0.60; p < 0.01) than their male counterparts. CONCLUSIONS: Female sports medicine physicians may experience bias in their practice during pregnancy and postpartum.

Association between Self-reported Overtraining Syndrome and Symptoms in High School Track and Field Athletes.

Diagnosing overtraining syndrome is challenging and it is often correlated with other diseases, especially those related to low energy availability. Therefore, we investigated the prevalence of overtraining syndrome-like symptoms and correlative factors in 389 female and 572 male national-level high school track and field athletes. They were asked to complete a survey regarding their history of overtraining syndrome-like symptoms, injuries, and diseases. The survey results revealed that 13.4% (52/389) of female and 13.3% (76/572) of male athletes had a history of overtraining syndrome-like symptoms. Logistic regression analysis showed that training hours per day (odds ratio, 1.74; 95% confidence interval, 1.12-2.71) was an associated factor in female athletes, while rest days per week (odds ratio, 0.61; 95% confidence interval, 0.37-1.00), skipping meals (odds ratio, 3.73; 95% confidence interval, 1.50-9.29), and having snacks/light meals on a regular basis (odds ratio, 0.46; 95% confidence interval, 0.26-0.83) were the associated factors in male athletes. In conclusion, athletes with overtraining syndrome-like symptoms may be prone to injuries and diseases. Hence, although overtraining syndrome is difficult to diagnose, further attention should be paid to minimize overtraining syndrome-related risks.

IOC consensus statement on recommendations and regulations for sport events in the heat.

This document presents the recommendations developed by the IOC Medical and Scientific Commission and several international federations (IF) on the protection of athletes competing in the heat. It is based on a working group, meetings, field experience and a Delphi process. The first section presents recommendations for event organisers to monitor environmental conditions before and during an event; to provide sufficient ice, shading and cooling; and to work with the IF to remove regulatory and logistical limitations. The second section summarises recommendations that are directly associated with athletes' behaviours, which include the role and methods for heat acclimation; the management of hydration; and adaptation to the warm-up and clothing. The third section explains the specific medical management of exertional heat stroke (EHS) from the field of play triage to the prehospital management in a dedicated heat deck, complementing the usual medical services. The fourth section provides an example for developing an environmental heat risk analysis for sport competitions across all IFs. In summary, while EHS is one of the leading life-threatening conditions for athletes, it is preventable and treatable with the proper risk mitigation and medical response. The protection of athletes competing in the heat involves the close cooperation of the local organising committee, the national and international federations, the athletes and their entourages and the medical team.

Gender bias in sports medicine: an international assessment of sports medicine physicians' perceptions of their interactions with athletes, coaches, athletic trainers and other physicians.

OBJECTIVES: To evaluate the difference between female and male sports medicine physicians regarding disrespectful attitudes and sexual harassment perceived from athletes, coaches, physicians, athletic trainers (ATs) and organisations/administrations. METHODS AND STUDY DESIGN: anonymous survey was distributed to sports medicine physicians practicing in 51 countries. χ2 analysis was used to detect differences between female and male sports medicine physicians and logistic regression analysis was used to determine the independent variables that affect disrespectful attitudes and sexual harassment from sports participants. RESULTS: 1193 sports medicine physicians (31.9% female) participated from 51 countries. The survey revealed that female physicians, compared with male physicians, perceive significantly more disrespect or have their judgement questioned more by the following categories: male and female athletes, male and female coaches, female physicians with more years of experience, male physicians (regardless of years of experience), male and female ATs and organisation/administrations (all p<0.05). The only category where the frequency of disrespect was perceived equally by male and female physicians was during their interactions with female physicians who have the same or lesser years of experience. Female sports medicine physicians noted more sexual harassment than male physicians during interactions with male athletes, coaches, ATs and physicians (all p<0.001). In the logistic regression, gender was a related factor for perceiving disrespect, especially from male coaches (OR=2.01) and physicians with more years of experience (OR=2.18). CONCLUSIONS: Female sports medicine physicians around the world experience disrespectful attitudes, questioning of their judgement and are sexually harassed significantly more often than male counterparts.

Athlete Medical Services at the Marathon and Race Walking Events During Tokyo 2020 Olympics.

Epidemiological data from race walk and marathon events suggest that a high incidence rate of exertional heat illness is associated with high ambient temperature and relative humidity. The 2020 Summer Olympics in Tokyo was no exception, which led the organizing committee to relocate the race walk and marathon competitions to Sapporo, which was predicted to experience much milder heat. Nonetheless, during the Games, Sapporo recorded the highest daytime ambient temperature in the past 97 years, with consecutive days over 30°C from July 22nd to August 7th, 2021. Five events (men's and women's 20 km race walk, men's 50 km race walk, women's and men's marathon) were held in Sapporo from August 5th to August 8th, 2021. The percentage of athletes who did not finish (DNF) in each event was 8.8% in men's 20 km race walk, 20.3% in men's 50 km race walk, 8.6% in women's 20 km race walk, 17.1% in women's marathon and 28.3% in men's marathon. A total of fifty athletes were transferred to the athlete medical station: 28 athletes completed the race (i.e., collapsed after finish line), while 24 were DNF athletes transported from the course. Forty-eight (96%) of athletes who were admitted to the athlete medical station exhibited signs and symptoms of exertional heat illness. Two athletes diagnosed with exertional heat stroke and three athletes diagnosed with severe heat exhaustion (rectal body temperature >39.5°C with or without central nervous system disturbance) were cooled using whole-body cold water immersion at the heat deck located within the athlete medical station. All athletes who were cooled successfully recovered without any complications. These athletes required an average of 14 ± 9.4 min (range, 6-30 min) to cool their rectal temperature below 39°C. These results show the importance for event organizers to prepare strategies to keep athletes cool, such as an ample amount of ice and water to supply whole-body cold water immersion.

Factors that affect menarche in Japanese national-level track-and-field athletes.

OBJECTIVES: The minimum body mass index (BMI) required to menarche and the relationship between the training onset age of sports and menarche is not fully understood. The aim of this study is to elucidate the minimum BMI required to attain menarche in female adolescent athletes competing at a national level, and to determine how the occurrence of menarche is associated with training onset age in track-and-field athletes. METHODS: Overall, 134 sprinters and 44 long-distance (LD) runners of ninth-grade females at a national level were enrolled and an anonymous questionnaire was administered. RESULTS: As BMI increased, the proportion of athletes who had attained menarche increased. The BMI cutoff values for menarche were 17.3 and 17.1 kg/m2 for sprinters and LD runners, respectively. Menarche had not occurred in almost 50% of the LD runners who began training at elementary school, and among LD runners, those who began training at elementary school had 18.4 higher odds of not attaining menarche until the age of 15 years as opposed to those who started training after elementary school. CONCLUSIONS: The BMI cutoff values could be an indicator for menarche in sprinters and LD runners. For LD runners, starting to compete at elementary school could be a risk factor for delayed menarche.

A Guide for Businesses and Employers Responding to Novel Coronavirus disease (COVID-19): 4th edition.

The Japanese Society of Travel and Health (JSTH) and the Japanese Society for Occupational Health (JSOH) have compiled "Novel Coronavirus Information" together as a joint document, which has been shared with the public on their respective websites since February 2020. In May 11, 2020, this document was to be published as "A Guide for Businesses and Employers Responding to Novel Coronavirus Disease (COVID-19)" (hereinafter referred to as "this Guide"). This Guide was prepared for persons in charge of COVID-19 control measures in their workplace. It should be used at the discretion of each business operator according to their workplace environment. The examples of infection control measures shown in this Guide are not guaranteed to work for all situations, and they do not limit or bind actual measures being put in place. When selecting actual measures, it is necessary to obtain new information and thoroughly understand individual cases and situations. This Guide was prepared based on findings and reports about the virus and response measures taken by the relevant ministries (Ministry of Health, Labour and Welfare, Ministry of Foreign Affairs, etc.) that could be confirmed as of December 15, 2020. Therefore, the contents of this Guide may need to be modified in the future, depending on changes in the situations mentioned above. In the preparation of this Guide, every effort has been made to ensure the accuracy of currently obtainable information. However, neither JSTH or JSOH shall be held liable for any unfavorable circumstance, such as loss and damage (including lost profits and various expenses), harmful rumors, etc. experienced by a business operator, his/her employees, and any other persons concerned as a result of various measures considered/implemented using this Guide by persons responsible for infection control in the workplace.

Wearable and telemedicine innovations for Olympic events and elite sport.

Rapid advances in wearable technologies and real-time monitoring have resulted in major inroads in the world of recreational and elite sport. One such innovation is the application of real-time monitoring, which comprises a smartwatch application and ecosystem, designed to collect, process and transmit a wide range of physiological, biomechanical, bioenergetic and environmental data using cloud-based services. We plan to assess the impact of this wireless technology during Tokyo 2020, where this technology could help characterize the physiological and thermal strain experienced by an athlete, as well as determine future management of athletes during a medical emergency as a result of a more timely and accurate diagnosis. Here we describe some of the innovative technologies developed for numerous sports at Tokyo 2020 ranging from race walking (20 km and 50 km events), marathon, triathlon, road cycling (including the time trial event), mountain biking, to potentially team sports played outdoors. A more symbiotic relationship between sport, health and technology needs to be encouraged that harnesses the unique demands of elite sport (e.g., the need for unobtrusive devices that provide real-time feedback) and serves as medical and preventive support for the athlete's care. The implementation of such applications would be particularly welcome in the field of medicine (i.e., telemedicine applications) and the workplace (with particular relevance to emergency services, the military and generally workers under extreme environmental conditions). Laboratory and field-based studies are required in simulated scenarios to validate such emerging technologies, with the field of sport serving as an excellent model to understand and impact disease.

Bone parameters of elite athletes with oligomenorrhea and prevalence seeking medical attention: a cross-sectional study.

INTRODUCTION: Since the definition of secondary amenorrhea is cessation of regular menses for more than 3 months, it is likely that athletes with irregular menstrual cycles, including oligomenorrhea, do not consider the condition as serious. However, the consequences of untreated oligomenorrhea have not been investigated in elite track and field athletes. MATERIALS AND METHODS: The cohort consisted of 91 elite-level track and field athletes. Body compositions, including bone parameters and bone turnover markers (BTMs), were measured. RESULTS: Among the 91 participants, 52 were eumenorrheic and 33 were oligomenorrheic. The eumenorrheic athletes had significantly higher bone mineral density (BMD) and bone mineral content (BMC) of the lumbar spine, lower extremities, and whole body than had the oligomenorrheic athletes (p < 0.01). There were no significant differences in BTMs between the two groups, but oligomenorrheic athletes had significantly lower percent body fat. CONCLUSION: More than 40% of the elite-level female track and field athletes in this study reported menstrual disorders with oligomenorrhea as the most common. However, none sought medical attention. As compared to the eumenorrheic athletes, the oligomenorrheic athletes had lower BMC and BMD. Hence, if an athlete is oligomenorrheic, bone parameter measurements are considerably important.

Bone Metabolism, Bone Mineral Content, and Density in Elite Late Teen Female Sprinters.

With intensive training, bone injuries are a major concern for athletes. To assess bone condition, we often measure bone turnover markers, bone mineral content and density; however, in junior athletes, it is not easy to distinguish changes caused by bone injuries from those caused by growth, because the metabolism is increased in both cases. Moreover, although some studies have examined female endurance athletes, knowledge regarding changes in static and dynamic bone conditions in late teen athletes is limited. In this study, we measured the bone mineral content and density, as well as bone turnover markers, in 40 elite female sprinters in their late teens. Whole body mode dual-energy X-ray absorptiometry was performed to measure bone mineral content and density. Blood samples were collected to determine bone resorption and formation markers at the end of track season in 2016 and during the same period of the following year. Body weight and bone mineral content significantly increased, and tartrate-resistant acid phosphatase type 5b, bone-type alkaline phosphatase, and osteocalcin significantly decreased after a year. Furthermore, the rate of change in bone mineral content was higher in younger athletes, indicating that bone growth approaches completion in the late teen years and that bone metabolism accordingly decreases.