Regional bone mineral density in male athletes: a comparison of soccer players, runners and controls

Bone health and the masters runner

Masters runners are often defined as those ages 35 years and older who train and compete in running events. These runners represent a growing population of the overall running community and experience running-related injuries including bone stress injuries (BSIs). Similar to younger runners, health considerations in masters runners include the goal to optimize bone health with focus on mitigating age-associated loss of bone strength and preventing BSIs through a combination of ensuring appropriate physical activity, optimizing nutrition, and correcting faulty biomechanics. Importantly, BSIs in masters runners may include characteristics of both overuse injury from insufficient recovery and failure of bone weakened by age-related loss of bone (insufficiency fractures). This narrative review covers the limited available research on strategies to optimize bone health in masters runners. Applying knowledge on masters athletes and extrapolating from other populations, we propose strategies on treatment and prevention of BSIs. Finally, the review highlights gaps in knowledge that require further age-specific discoveries to advance treatment and prevention.

Changes of bone turnover markers and testosterone in Japanese male endurance runners: a pilot study

INTRODUCTION

The bone metabolism of male endurance runners during a competitive season has been little studied. Furthermore, Japanese runners have a special competitive season. This study aimed to investigate the change of bone turnover markers (BTMs) and other hormones in Japanese male endurance runners.

MATERIALS AND METHODS

We investigated biochemical markers, bone formation and resorption markers and sex hormones, body composition using dual-energy X-ray absorptiometry (DXA), and training volume during a competitive season. 11 (age: 24.0 ± 4.3 years) Japanese male endurance runners were analyzed in this study. They participated in all measurements three times a year: the baseline (BL), the post-track period (PT), and the road race period (RR).

RESULTS

Fat mass (FM) and percentage of body fat (% body fat) at RR (p = 0.009, p = 0.009) were lower than at BL. Specific bone alkaline phosphatase (BAP) decreased at PT (p = 0.004) and RR (p = 0.004) compared with BL. However, the bone resorption marker did not change. Free testosterone at PT (p = 0.032) was lower than BL. There was no correlation with blood variables and body composition or training volume.

CONCLUSION

BAP and testosterone in Japanese male endurance runners decreased during the competitive season. However, there was no correlation between blood variables and training volume.

The Relationship Between Muscular Strength, Jump Power, and Bone Health in Collegiate Distance Runners

Participation in sports, especially those involving impact loading, enhance bone mineral content (BMC) and density (BMD). Additionally, participation in impact loading sports may strengthen relationships between strength or power and bone variables. The purpose of this investigation was to examine relationships between measures of muscular performance and bone variables in Division I endurance athletes (29 males, 31 females, 19.6 ± 1.4 years). Dual-energy x-ray absorptiometry (DXA) scans were analyzed at the anterior-posterior (AP) and lateral (LAT) spine, femoral neck (FN), total hip (TH), whole body (WB), and ultra-distal forearm (UD) for BMC and BMD measures. WB scans provided information for bone-free lean mass (BFLM). Performance measures included absolute, and relative (to body weight), grip strength (GS) and absolute lower body power (LBP) derived from a vertical jump. Pearson correlation coefficients were determined between bone variables and muscular performance measures. Hierarchical multiple regression was used to quantify the variance explained in bone variables. Male runners showed strong relationships between absolute and relative GS and numerous bone variables. Female runner had significant relationships between absolute jump power and numerous bone variables. Sex, GS, and LBP explained 41-76% of BMC at the various bone sites and 12-30% of BMD. Results indicate that in collegiate men, greater strength is related to higher BMC and BMD, however this was not the case for women. In female collegiate distance runners, higher jump power was related to greater BMC and BMD.

Relationship between Football-Specific Training Characteristics and Tibial Bone Adaptation in Male Academy Football Players

We examined the relationship between football-specific training and changes in bone structural properties across a 12-week period in 15 male football players aged 16 years (Mean ± 1 SD = 16.6 ± 0.3 years) that belonged to a professional football academy. Tibial scans were performed at 4%, 14% and 38% sites using peripheral quantitative computed tomography immediately before and 12 weeks after increased football-specific training. Training was analysed using GPS to quantify peak speed, average speed, total distance and high-speed distance. Analyses were conducted with bias-corrected and accelerated bootstrapped 95% confidence intervals (BCa 95% CI). There were increases in bone mass at the 4% (mean ∆ = 0.15 g, BCa 95% CI = 0.07, 0.26 g, g = 0.72), 14% (mean ∆ = 0.04 g, BCa 95% CI = 0.02, 0.06 g, g = 1.20), and 38% sites (mean ∆ = 0.03 g, BCa 95% CI = 0.01, 0.05 g, g = 0.61). There were increases in trabecular density (4%), (mean ∆ = 3.57 mg·cm^-3, BCa 95% CI = 0.38, 7.05 mg·cm^-3, g = 0.53), cortical dentsity (14%) (mean ∆ = 5.08 mg·cm^-3, BCa 95% CI = 0.19, 9.92 mg·cm^-3, g = 0.49), and cortical density (38%) (mean ∆ = 6.32 mg·cm^-3, BCa 95% CI = 4.31, 8.90 mg·cm^-3, g = 1.22). Polar stress strain index (mean ∆ = 50.56 mm³, BCa 95% CI = 10.52, 109.95 mm³, g = 0.41), cortical area (mean ∆ = 2.12 mm², BCa 95% CI = 0.09, 4.37 mm², g = 0.48) and thickness (mean ∆ = 0.06 mm, BCa 95% CI = 0.01, 0.13 mm, g = 0.45) increased at the 38% site. Correlations revealed positive relationships between total distance and increased cortical density (38%) (r = 0.39, BCa 95% CI = 0.02, 0.66), and between peak speed and increased trabecular density (4%) (r = 0.43, BCa 95% CI = 0.03, 0.73). There were negative correlations between total (r = -0.21, BCa 95% CI = -0.65, -0.12) and high-speed distance (r = -0.29, BCa 95% CI = -0.57, -0.24) with increased polar stress strain index (38%). Results suggest that despite football training relating to increases in bone characteristics in male academy footballers, the specific training variables promoting adaptation over a 12-week period may vary. Further studies conducted over a longer period are required to fully elucidate the time-course of how certain football-specific training characteristics influence bone structural properties.

A comparison of the associations between bone turnover markers and different sports fields: combat versus team sports

Sedentary life brings risks that include osteoporosis, while physical activity has many benefits for health in general and the skeletal system. Irisin is a hormone-like myokine regulated by mechanical force and it contributes to cortical and trabecular bone mineral density. This study aimed to investigate the effects of different types of sports on bone health by measuring elite athletes’ fibronectin type III domain 5 (FNDC5), N-terminal collagen type I extension propeptide (PINP), and C-terminal cross-linking telopeptide of type I collagen (CTXI) levels. Combat sports athletes, team sports athletes, and sedentary control subjects were enrolled. Serum levels of proteins were measured by ELISA. FNDC5 levels of elite athletes were higher compared to the sedentary controls (P=0.0014). The highest FNDC5 level was measured in wrestlers among all considered groups. The PINP levels of the athletes were also higher than those of the sedentary control group (P=0.1431). The highest PINP level was determined in boxers. The CTXI levels of the athletes were lower than those of the sedentary control (P<0.0001). The lowest CTXI level was seen in boxers. The FNDC5 and PINP levels of combat sports athletes were higher than those of team sports athletes (P=0.0134 and P=0.0262, respectively), while the CTXI levels of combat sports athletes were lower than those of team sports athletes (P<0.0001). Our results indicated that FNDC5, PINP, and CTXI levels are associated with physical activity. The effect of the exercises performed by athletes of specific sports on bone health has not been studied in much detail before. Combining different exercises for athletes of a particular sport may be more beneficial for bone health.

A 2-Year Longitudinal Study of Bone Mineral Density in Collegiate Distance Runners

ABSTRACT

Brimacomb, OE, Martinez, MP, McCormack, WP, and Almstedt, HC. A 2-year longitudinal study of bone mineral density in collegiate distance runners. J Strength Cond Res XX(X): 000-000, 2022-The purpose of this investigation was to examine changes in bone mineral density (BMD) of male and female collegiate distance runners over 2 years. Bone mineral density of 29 collegiate distance runners (16 men and 13 women) were measured 5 times over 24 months using dual-energy x-ray absorptiometry (DXA) at the anterior-posterior (AP) and lateral (LAT) spine, femoral neck (FN), total hip (TH), whole body (WB), and ultradistal (UD) forearm. Repeated-measures multivariate analysis of covariance, with bone-free lean mass (BFLM) as covariate, was used to compare mean BMD values. Adjusted for BFLM, there were no significant differences (p > 0.05) in BMD at any site between sexes. There were no significant differences at the AP or LAT spine, FN, or WB between visit 1 and 5 for either sex. There was a significant increase in BMD (p = 0.044) at the UD forearm over 2 years in males. However, 56% of the men (n = 9) had a Z-score < -1.0 at the UD forearm. Seven of 11 women had Z-scores < -1.0 at the LAT spine and 4 of 13 had Z-scores < -1.0 at the AP spine. There were no significant changes in BMD at any site over the 2-year time frame, except a significant increase in BMD at the nondominant forearm in men. The spine appears to be an area of concern for women in this study when examining Z-score results. Coaches and medical staff need to continually educate collegiate endurance athletes about the importance of achieving and maintaining BMD through their college years.

Characteristics of total body and appendicular bone mineral content and density in Japanese collegiate Sumo wrestlers

The purpose of this study was to explore the characteristics of total body and appendicular bone mineral content (BMC, kg) and bone mineral density (BMD, g/cm²) in Japanese collegiate Sumo wrestlers. A total of 54 male college Sumo wrestlers were recruited for the study and assigned to two groups according to their body weight (middleweight, 85–115 kg, n = 23 and heavyweight, > 115 kg, n = 31). The BMC, BMD, fat mass, and lean soft tissue mass (LSTM) values were measured using dual-energy X-ray absorptiometry for the total body and appendicular regions. Heavyweight Sumo wrestlers had significantly higher body weight, fat mass, and LSTM compared to middleweight Sumo wrestlers. The mean total body and regional BMC values were significantly higher in heavyweight than in middleweight Sumo wrestlers. The total body and leg BMD was significantly higher in heavyweight than in middleweight Sumo wrestlers, and was significantly correlated with body weight, but not arm BMD. The present study indicates that BMC and BMD might not sharply elevate among even heavyweight athletes, although heavier Sumo wrestlers had a greater BMC and BMD.

Comparison of Tibial Geometry, Density, and Strength in College-Aged Female Eumenorrheic Dancers, Gymnasts, and Runners: A Peripheral Quantitative Computed Tomography Study

INTRODUCTION

Weightbearing activities such as gymnastics, soccer, weightlifting, and running have often been used as benchmarks in skeletal research since they have been shown to promote densitometric and geometric benefits. In comparison with other sports, there is a paucity of information in relation to dance and its osteogenic potential.

OBJECTIVE

This study aimed to compare tibial geometry, density, and strength in college-aged dancers versus gymnasts and runners.

METHODS

A total of 60 trained eumenorrheic collegiate-aged female dancers (n = 11), gymnasts (n = 11), runners (n = 19), and sedentary controls (n = 19) were included in the study. Bone measurements, including total area (ToA), volumetric (total vBMD) and cortical density (CoD), compressive bone strength (BSI), and polar strength stress index (SSIp) of the dominant limb, were assessed using peripheral quantitative computed tomography (pQCT) at the distal and proximal tibia (4% and 66% of limb length).

RESULTS

No significant differences in ToA, CoD, CoA, and total vBMD were found between dancers and the comparison athletes at the measured sites. In addition, strength indices (BSI and SSIp) at the distal and proximal sites were similar between the dancing and both athlete groups.

CONCLUSION

Results suggest dance elicits similar structural adaptations at the tibia compared to benchmark high-impact and repetitive impact sports; thus, indicating dance, in its various forms, can have a positive effect on important bone variables that influence density and strength. These adaptations may potentially delay or prevent bone fragility later in life. Future studies should compare individual styles of dance separately, longitudinally, and include other important lower (e.g., hip) and upper body (e.g., radius) sites to further identify which forms provide the greatest osteogenic benefits.

Dietary-Lifestyle Patterns Associated with Bone Turnover Markers, and Bone Mineral Density in Adult Male Distance Amateur Runners—A Cross-Sectional Study

Background: Excessive mileage can be detrimental to bone mineral density among long-distance runners. The negative effects of mileage could be alleviated by appropriate nutrition. The purpose of this study was to analyse the dietary-lifestyle patterns in relation to bone mineral density and bone turnover markers among amateur marathoners. Methods: A total of 53 amateur male distance runners were divided into two clusters by k-means cluster analysis. Bone mineral density was measured by dual X-ray absorptiometry (DXA). Blood was drawn to analyse bone resorption marker C-terminal telopeptide (cTX) and bone formation marker amino-terminal propeptide of type I collagen (PINP). Food frequency intake and lifestyle information were measured by multicomponent questionnaire KomPAN^®. Yearly average mileage per month was taken from each participant. Results: There were two distinguished clusters: Less-healthy-more-active-low-Z-score (LessHA) (n = 33) and More-healthy-less-active-high-Z-score (MoreHLA) (n = 20). LessHA had a lower frequency intake of pro-healthy food groups, a lower number of meals during a typical day, and a higher mileage training than the group of athletes who followed the MoreHLA. Athletes following the LessHA pattern also had a lower Z-score in the lumbar spine and femoral bone and a lower PINP. Conclusion: The current study suggests that pro-healthy dietary patterns and lower mileage may favour higher bone mineral density in male amateur marathoners.

Relationship Between Ground Reaction Force Characteristics and Bone Mineral Density of the Hip and Spine in Male Runners

The purpose of this study was to determine the relationship between running ground reaction force (GRF) characteristics and hip and lumbar spine bone mineral density (BMD) values in male runners. Individuals who ran at least 48.3 km per week and were injury-free were recruited. Kistler force plates collected running vertical and anteroposterior GRF data. A Hologic Discovery W bone densitometer measured lumbar spine and five regional hip BMD values. Only runners who consistently used a rear foot strike pattern were included (n = 32). Pearson correlation coefficients were calculated between BMD values and various GRF values and step-wise multiple regression was run to predict BMD values from the various GRF values. The vertical impact force was significantly correlated with the lumbar spine and four of the five hip BMD values (r > 0.374, p < 0.035). Both the peak early loading rate (ELR) and average ELR were significantly correlated with the lumbar spine and Ward's triangle BMD (r > 0.430, p < 0.014), while the average active loading rate was correlated only with the Ward's triangle BMD (r = 0.438, p = 0.012). Multiple regression revealed the peak impact force was the predictor for every hip region BMD other than the trochanter and the average ELR as a predictor for the lumbar spine BMD. The peak braking force was negatively correlated with the Ward's triangle BMD (r = -0.414, p = 0.019). It appears that the large forces and loading rates associated with rear foot striking may be advantageous and predictive for BMD at the hip and spine.

The female athlete triad

The female athlete triad represents the 3 interrelated components: of energy availability (EA), menstrual function and bone health. Each component exists on a spectrum ranging from optimal health to dysfunction. Screening for the triad during the annual wellness exam, the preparticipation physical evaluation (PPE) or when the athlete presents with any single component can help identify athletes at risk. A multidisciplinary team is helpful in managing the treatment of the Triad which relies on improving EA. Screening, early recognition and aggressive treatment is important, especially in adolescent athletes to optimize bone health.

The Effects of Exercise on Bone Mineral Density in Men: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

The aim of this systematic review and meta-analysis was to provide an updated analysis, including the use of more robust methods, on the effects of exercise on bone mineral density in men. Randomised Control Trials of > 24 weeks and published in English up to 01/05/20 were retrieved from 3 electronic databases, cross-referencing, and expert review. The primary outcome measures were changes in FN, LS, and lower limb BMD Standardised effect sizes were calculated from each study and pooled using the inverse heterogeneity model. A statistically significant benefit of exercise was observed on FN BMD [g = 0.21 (0.03, 0.40), Z = 2.23 p = 0.03], with no observed statistically significant benefit of exercise on LS BMD [g = 0.10 (- 0.07, 0.26), Z = 1.15 p = 0.25]. This analysis provided additional evidence to recommend ground- and/or joint-reaction force exercises for improving or maintaining FN, but not LS BMD. Additional well-designed RCTs are unlikely to alter this evidence, although interventions that include activities that directly load the lumbar spine are needed to ensure this is not a potential method of improving LS BMD.

Effects of competitive physical activity on serum irisin levels and bone turnover markers

BACKGROUND

Irisin, a myokine, is a polypeptide derived from the cleavage of the extracellular domain of fibronectin domain-containing protein 5, a receptor that is present on different tissues (skeletal muscle, pericardium, myocardium, and brain), whose functions are not yet fully defined.

PURPOSE

The main aim of our study was to evaluate the effect of competitive physical activity on serum irisin levels and bone turnover markers.

METHODS

Fifteen male footballers and an equal number of subjects of the same age and gender, but with a predominantly sedentary lifestyle, had their serum levels of irisin and bone turnover markers measured. Bone mineral status was evaluated in both groups by quantitative bone ultrasound of the calcaneus. In addition, only in footballers, biochemical analyses were repeated after 3 months.

RESULTS

We did not observe significant differences in the serum levels of calcium, phosphorus, and parathyroid hormone between the two groups. The footballers had significantly higher quantitative bone ultrasound, 25-OH vitamin D, and creatinine values than the controls. There were also no significant differences in the bone alkaline phosphatase, carboxy-terminal telopeptide of type I collagen, osteoprotegerin, sclerostin or Dkk-1 values, while the irisin levels (+ 89%, p < 0.001) and RANKL were significantly higher in the footballers compared to those in the controls.

CONCLUSION

Our study shows that footballers have significantly higher serum irisin values than the general population. Irisin could be the "trait d'union" between bone health and physical activity.

High bone mineral density in lifelong trained female team handball players and young elite football players

PURPOSE

Low bone mineral density (BMD) and fractures are a major concern in the female population and preventative strategies are needed. Whether team sports participation may reduce age-related bone loss in elderly women is still uncertain.

METHODS

One hundred and thirty healthy, non-smoking women participated in this cross-sectional study, i.e., elderly (60-80 years) team handball players (EH, n = 35), elderly untrained controls (EC, n = 35), young (18-30 years) elite football players (YF, n = 30) and young untrained controls (YC, n = 30). A whole-body and two regional dual-energy X-ray absorptiometry (DXA) scans were performed to evaluate BMD and a blood sample was collected for measurement of bone turnover markers (BTMs).

RESULTS

EH had higher BMD in all regions of the lumbar spine, except for L1, compared to EC (8-10%), and higher BMD in the femoral Ward's triangle (9%) and trochanter (7%) of the left leg. Furthermore, EH had higher mean leg BMD (8%) and whole-body BMD (5%) than EC. EH and YC had similar BMD in femoral trochanter, L1-L4 and mean leg despite an age difference of ~ 40 years. YF had higher BMD in all regions of the proximal femur (18-29%) and lumbar spine (12-16%) compared to YC, as well as higher mean leg BMD (20%) and whole-body BMD (13%). Sclerostin was 14% lower in EH compared to EC. YF showed higher PINP (98%), osteocalcin (57%), and CTX (83%) compared to YC.

CONCLUSION

Lifelong team handball training and elite football training are associated with superior bone mineralization and changed bone turnover in elderly and young women.

Bone mineral density in high-level endurance runners: part A-site-specific characteristics

PURPOSE

Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies.

METHOD

The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes.

RESULTS

Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners.

CONCLUSION

Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic make-up alongside mechanical loading probably influence BMD across the adult lifespan.

Soccer participation is associated with benefits in tibial bone cross-sectional geometry and strength in young women

BACKGROUND

Soccer has been hypothesized to be an ideal sport to stimulate favorable changes in bone properties due the high-intensity, multidirectional movements performed during play. The purpose of this study was to determine if participation in soccer is associated with enhanced bone properties such as volumetric bone mineral density (vBMD), cross-sectional geometry, and estimated strength in the tibias of young, healthy women.

METHODS

Twenty female soccer players (20±1 yr) and twenty mass- and height-matched healthy women (21±1 yr) participated in this cross-sectional study. Peripheral quantitative computed tomography (XCT 3000; Stratec Medizintechnik, Pforzheim, Germany) was used to assess bone characteristics, including vBMD, cross-sectional moments of inertia (CSMI), and strength/strain index (SSI) at 14%, 38%, and 66% of the tibial length proximal to the distal end plate. One-way multivariate analysis of variances was run to determine the influence of soccer training history on tibial properties.

RESULTS

Compared to healthy controls, soccer players had approximately 1.5% - 3% lower cortical vBMD but 18.5% - 30% greater CSMI and 16.5% -19% greater SSI at the three cross-sectional sites along the tibial diaphysis (all p < 0.05).

CONCLUSIONS

These results suggest that soccer participation is associated with favorable bone cross-sectional geometry and estimates of bone strength. However, randomized controlled intervention trials are needed to confirm whether soccer participation results in favorable bone adaptations in young, healthy adults.

Promoting adaptive bone formation to prevent stress fractures in military personnel

Mechanical loading leads to adaptive bone formation - the formation of new bone on existing skeletal surfaces - which increases bone strength and fatigue resistance. The same mechanical loading can also cause microdamage to bone and development of a stress fracture through targeted remodelling. Stress fractures are common in military recruits and cause significant morbidity, lost training time, and discharge from military service. This narrative review proposes strategies to promote adaptive bone formation as a novel approach to mitigate the risk of stress fracture injuries during arduous military training. Exercise that is unaccustomed, dynamic, high-impact, multidirectional, intermittent, and includes extended rest periods to restore bone mechanosensitivity, is most osteogenic. New bone formation can take up to one year to mineralize, and so new exercise training programmes should be initiated well in advance of military activities with high risk of stress fracture. Bone mechanosensitivity is highest in adolescence, before puberty, and so increasing physical activity in youth is likely to protect skeletal health in later life, including for those in the military. Recent data show that adaptive bone formation takes place during initial military training. Adaptive bone formation can also be supported with adequate sleep, vitamin D, calcium, and energy availability. Further evidence on how strategies to promote adaptive bone formation affect stress fracture risk are required. Adaptive bone formation can be optimized with a range of training and nutritional strategies to help create a resilient skeleton, which may protect against stress fracture throughout military service.

The Male Athlete Triad-A Consensus Statement From the Female and Male Athlete Triad Coalition Part 1: Definition and Scientific Basis

ABSTRACT

The Male Athlete Triad is a syndrome of 3 interrelated conditions most common in adolescent and young adult male endurance and weight-class athletes and includes the clinically relevant outcomes of (1) energy deficiency/low energy availability (EA) with or without disordered eating/eating disorders, (2) functional hypothalamic hypogonadism, and (3) osteoporosis or low bone mineral density with or without bone stress injury (BSI). The causal role of low EA in the modulation of reproductive function and skeletal health in the male athlete reinforces the notion that skeletal health and reproductive outcomes are the primary clinical concerns. At present, the specific intermediate subclinical outcomes are less clearly defined in male athletes than those in female athletes and are represented as subtle alterations in the hypothalamic-pituitary-gonadal axis and increased risk for BSI. The degree of energy deficiency/low EA associated with such alterations remains unclear. However, available data suggest a more severe energy deficiency/low EA state is needed to affect reproductive and skeletal health in the Male Athlete Triad than in the Female Athlete Triad. Additional research is needed to further clarify and quantify this association. The Female and Male Athlete Triad Coalition Consensus Statements include evidence statements developed after a roundtable of experts held in conjunction with the American College of Sports Medicine 64th Annual Meeting in Denver, Colorado, in 2017 and are in 2 parts-Part I: Definition and Scientific Basis and Part 2: The Male Athlete Triad: Diagnosis, Treatment, and Return-to-Play. In this first article, we discuss the scientific evidence to support the Male Athlete Triad model.

The Male Athlete Triad-A Consensus Statement From the Female and Male Athlete Triad Coalition Part II: Diagnosis, Treatment, and Return-To-Play

ABSTRACT

The Male Athlete Triad is a medical syndrome most common in adolescent and young adult male athletes in sports that emphasize a lean physique, especially endurance and weight-class athletes. The 3 interrelated conditions of the Male Athlete Triad occur on spectrums of energy deficiency/low energy availability (EA), suppression of the hypothalamic-pituitary-gonadal axis, and impaired bone health, ranging from optimal health to clinically relevant outcomes of energy deficiency/low EA with or without disordered eating or eating disorder, functional hypogonadotropic hypogonadism, and osteoporosis or low bone mineral density with or without bone stress injury (BSI). Because of the importance of bone mass acquisition and health concerns in adolescence, screening is recommended during this time period in the at-risk male athlete. Diagnosis of the Male Athlete Triad is best accomplished by a multidisciplinary medical team. Clearance and return-to-play guidelines are recommended to optimize prevention and treatment. Evidence-based risk assessment protocols for the male athlete at risk for the Male Athlete Triad have been shown to be predictive for BSI and impaired bone health and should be encouraged. Improving energetic status through optimal fueling is the mainstay of treatment. A Roundtable on the Male Athlete Triad was convened by the Female and Male Athlete Triad Coalition in conjunction with the 64th Annual Meeting of the American College of Sports Medicine in Denver, Colorado, in May of 2017. In this second article, the latest clinical research to support current models of screening, diagnosis, and management for at-risk male athlete is reviewed with evidence-based recommendations.

Endurance running prevents the age-related decline of calcaneal bone stiffness

This investigation presents a comparison of calcaneus bone stiffness of endurance runners of different ages and age-matched controls. We found that there was an age-associated decline in calcaneus bone stiffness in the control group while endurance runners prevented this decline, with a higher effect as the participants increased their age.

PURPOSE

Previous investigations have found that endurance runners have higher bone mineral density and other bone quality variables in mechanically loaded bones. However, it is unknown if endurance running might counteract the decline in bone stiffness that occurs with age. The purpose of this study was to compare calcaneus bone stiffness of endurance runners of different ages to age-matched controls.

METHODS

In a descriptive cross-sectional study, 182 endurance-trained male runners and 116 healthy untrained male controls underwent an ultrasonographic assessment of the calcaneus bone in the right and left heels. Calcaneal bone stiffness was calculated from assessments of the broadband ultrasound attenuation and the speed of sound.

RESULTS

The line of best fit for the association between age and calcaneus stiffness was different between marathoners and controls (Z =  - 2.1, P = 0.02). A two-way ANCOVA (condition × age) with body mass, and body mass index as covariates, revealed that there were main effects of condition (F = 26.8, P < 0.01) and age (F = 4.2, P < 0.01) for calcaneus stiffness, with a significant interaction between these two factors (F = 2.8, P = 0.03). The post hoc analysis revealed that calcaneus stiffness was significantly higher in marathoners of 40-44 years (121.5 ± 18.2 vs 101.1 ± 21.3 arbitrary units [A.U.], P = 0.01), 45-49 years (121.5 ± 19.7 vs 104.3 ± 13.4 A.U., P = 0.04), and > 50 years (111.2 ± 17.9 vs 92.4 ± 16.0 A.U., P < 0.01) than their untrained counterparts of the same age with no statistically significant differences in the remaining age groups.

CONCLUSION

Endurance runners of > 40 years had higher values of calcaneus stiffness than controls, providing evidence to support the potential effect of endurance running to reduce the age-related decline on calcaneus bone stiffness.

Effects of Low Energy Availability on Bone Health in Endurance Athletes and High-Impact Exercise as A Potential Countermeasure: A Narrative Review

Endurance athletes expend large amounts of energy in prolonged high-intensity exercise and, due to the weight-sensitive nature of most endurance sports, often practice periods of dietary restriction. The Female Athlete Triad and Relative Energy Deficiency in Sport models consider endurance athletes at high-risk for suffering from low energy availability and associated health complications, including an increased chance of bone stress injury. Several studies have examined the effects of low energy availability on various parameters of bone structure and markers of bone (re)modelling; however, there are differences in findings and research methods and critical summaries are lacking. It is difficult for athletes to reduce energy expenditure or increase energy intake (to restore energy availability) in an environment where performance is a priority. Development of an alternative tool to help protect bone health would be beneficial. High-impact exercise can be highly osteogenic and energy efficient; however, at present, it is rarely utilized to promote bone health in endurance athletes. Therefore, with a view to reducing the prevalence of bone stress injury, the objectives of this review are to evaluate the effects of low energy availability on bone health in endurance athletes and explore whether a high-impact exercise intervention may help to prevent those effects from occurring.

Bone mineral density and hip structure changes over one-year in collegiate distance runners and non-athlete controls

Modification of bone is continuous throughout life and influenced by many factors, including physical activity. This study investigated changes in areal bone mineral density (aBMD) and hip structure among male and female collegiate distance runners and non-athlete controls over 12 months. Using dual-energy x-ray absorptiometry (DXA) and hip structure analysis (HSA) software, aBMD at the posterior-anterior (PA) and lateral spine, femoral neck, total hip (TH), whole body (WB), and bone geometry at the narrow neck (NN) of the femur was measured three times over 12 months. HSA included cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and Z-section modulus (Z). Male runners had significantly higher aBMD at TH and WB and greater CSA, CSMI, and Z than male controls at the end of 12 months. Female controls had higher aBMD at the PA spine than female runners at the end of 12 months. Male runners had significant increases in aBMD at the PA (p = 0.003) and lateral spine (p = 0.002), and TH (p = 0.002), female runners had significant decreases in aBMD at TH (p = 0.015) and WB (p = 0.002), male controls had significant increases in aBMD at the PA spine (p < 0.001) and WB (p < 0.001), and female controls had significant decreases in aBMD at lateral spine and TH (p = 0.008) over the year. When applying covariates of bone-free lean mass and vitamin D, male distance runners demonstrated significant improvement in CSA (3.602 ± 0.139 vs. 3.675 ± 0.122 cm², p = 0.05), CSMI (3.324 ± 0.200 to 3.467 ± 0.212 cm⁴, p < 0.05), and Z (1.81 ± 0.08 to 1.87 ± 0.08 cm³, p = 0.05) during the study. No other changes in hip structure occurred over the year. Distance running may be beneficial to aBMD and hip structure in college-age males but not females. Further research is needed on potential influences of weight-bearing activity, energy availability, and hormonal status on aBMD and hip structure in males and females.

Long-Term Patterns of Bone Mineral Density in an Elite Soccer Player

Changes in bone mineral density (BMD) have been associated with association football (soccer) participation. Seasonal changes in BMD of soccer players have been proposed as well. However, previous investigations were based on short-term observations. Actually, longitudinal investigation of BMD in soccer players is lacking, possibly because of frequent inter-club transfer, changes in club policy or continued availability of the relevant facilities. Dual-energy X-ray Absorptiometry (DXA)-measured areal BMD (aBMD) was obtained during the competitive season in an elite soccer player along 10 consecutive years. Findings showed that (1) aBMD tends to increase with age, independently of body mass; (2) The right (preferred, kicking) leg has higher aBMD than the left (non-preferred, support) one; (3) Meaningful (i.e., >least significant change, LSC) changes in aBMD take place along the season; and (4) The off-season (transition) period has no effect on aBMD. Findings prompt for future research aimed at clarifying the long-term and seasonal patterns of bone characteristics in soccer in relation with age and type/dose of training. Season-around, long-term scrutiny of bone status in soccer players would help controlling for possible changes/asymmetries in bone mineralization/strength.

Energy Intake Deficiency Promotes Bone Resorption and Energy Metabolism Suppression in Japanese Male Endurance Runners: A Pilot Study

It has been reported that male athletes face increased risk for low energy availability and resulting health consequences similar to female athletes. The present study aimed to reveal the energy status of Japanese male runners and to examine the association between energy deficiency and physiological characteristics such as energy metabolism, bone health, and hormonal status. Six male collegiate long-distance runners during a training season participated in this study. Energy intake (EI) was assessed using 3-day dietary records with food pictures. Exercise energy expenditure (EEE) was determined by the HR-VO₂ method. Body composition and bone status were measured by dual-energy X-ray absorptiometry. Energy availability (EA) was calculated by subtraction of EEE from EI and normalized by fat-free mass (FFM). Energy balance (EB) was calculated EI minus estimated total energy expenditure (TEE). Resting energy expenditure (REE) was measured by indirect calorimetry using the Douglas bag technique, and blood sampling was conducted to assess hormonal status. The mean EA of the subjects was 18.9 ± 6.8 kcal/kg FFM/day, and severe negative EB (range: -1444 ~ -722 kcal/d) was observed. REE of four runners was suppressed, and moreover, bone resorption was promoted in all subjects. The data in our study suggested that energy deficiency could promote bone resorption and energy metabolism suppression in Japanese male endurance runners. Additional short- and long-term studies are needed to clarify the health risks caused by energy deficiency in male athletes and explore strategies to prevent health problems related to energy deficiency in long-distance runners.

Effects of marathon race on selected myokines and sclerostin in middle-aged male amateur runners

In recent years, there has been increasing interest in the homeostatic response to extreme exercises, especially in the integrated function of muscle and bone. The aim of this study was to evaluate the effects of a marathon race on selected myokines and sclerostin in 10 male recreational runners (mean age 41 ± 7.7 years). Body composition, bone mineral density (BMD), and the serum concentration of myostatin, irisin, sclerostin, osteoprotegerin (OPG), 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH), high-sensitivity interleukin-6 (hsIL-6), tumor necrosis factor α (TNFα), high-sensitivity C-reactive protein (hsCRP) and myoglobin, were determined 24 h before and 24 h and 72 h after a marathon race. Post-marathon increases were observed in the levels of myostatin (1.2-fold), OPG (1.5-fold), and PTH (1.3-fold), hsIL-6 (1.9-fold), myoglobin (4.1-fold), hsCRP (fivefold), TNFα (2.6-fold), after 24 h; and in myostatin (1.2-fold), irisin (1.1-fold), sclerostin (1.3-fold), OPG (1.3-fold), and PTH (1.4-fold), hsIL-6 (1.4-fold), TNFα (1.9-fold), after 72 h compared to the baseline level. The results show that in response to the marathon run, a complex network of endocrine interactions is initiated. Further research is needed to fully elucidate the long-term impact of prolonged high intensity exercise on the human body.

Influence of Physical Activity Level on Composite Indices of Femoral Neck Strength in a Group of Young Overweight Men

The aim of the present study was to explore the influence of physical activity level on composite indices of femoral neck strength (compression strength index [CSI], bending strength index, and impact strength index) in a group of young overweight men. To do so, we compared composite indices of femoral neck strength in active overweight men and insufficiently active overweight men. They were divided into 2 groups based on their physical activity level: 70 active overweight men (engaging in more than 150 minutes of physical activity per week; 8.7 ± 4.8 h/wk) and 26 insufficiently active overweight men (engaging in less than 150 minutes of physical activity per week; 1.2 ± 0.7 h/wk). Height (m) and weight (kg) were measured, and body mass index (kg/m²) was calculated. Bone mineral density was measured by dual-energy X-ray absorptiometry at whole body, lumbar spine, total hip, and femoral neck. Body weight, lean mass, fat mass, and body mass index were not significantly different between the 2 groups. CSI, bending strength index, and impact strength index were significantly higher in active overweight men compared to insufficiently active overweight men. After adjustment for age, physical activity (h/wk) and lean mass, only CSI remained higher in active overweight men compared to insufficiently active overweight men. This study suggests that, in young overweight men, being active (engaging in more than 150 minutes of physical activity per week) is associated with greater composite indices of femoral neck strength. To our knowledge, this is the first study that finds a significant difference regarding composite indices of femoral neck strength between 2 groups of young overweight men with different levels of physical activity.

Sports and Metabolic Bone Disease

Physical activity (PA) increases bone mass and bone strength through different mechanisms and also reduces the risk of falls in the elderly, through proprioception and balance training. The benefits seen in adolescence continue into adulthood. Exercise delays and attenuates the effects of osteoporosis, and particular sports activities may be recommended to improve bone mineral density (BMD) of the spine or regional BMD, improve balance, and prevent falls. Stress injuries related to exercise are more common in osteopenic and osteoporotic individuals.Sports activity may in some cases be detrimental for bone health, with nutrition restriction a frequent cause for negative effects of the practice of PA on bone. The examples are the so-called female athlete triad of menstrual dysfunction resulting in reduced estrogen levels, low energy due to malnutrition, and decreased BMD. A similar triad is described in male athletes. This review analyzes the effects of sport on bone metabolism and in particular its relationship with metabolic bone disease.

A Simplified Prediction Model for Lower Extremity Long Bone Stress Injuries in Male Endurance Running Athletes

OBJECTIVE

Develop a prediction model for lower extremity long bone injuries (LBIs) in male endurance running athletes using dual-energy x-ray absorptiometry (DEXA).

DESIGN

Retrospective.

SETTING

Sports medicine department in a university athletic setting.

PARTICIPANTS

National Collegiate Athletic Association (NCAA) Division 1 white male endurance athletes (n = 27).

INDEPENDENT VARIABLES

Backward stepwise elimination was used to achieve a model that predicts LBI, by removing noncontributory variables (P > 0.10), using binary logistic regression. Independent prediction variables analyzed for model were as follows: (1) height (cm), body mass index (BMI) (kg/m), and total mass (kg); and (2) regional and total lean mass, fat mass, and bone density assessed using DEXA.

MAIN OUTCOME MEASURES

Dichotomous dependent variable was LBI.

RESULTS

Final constructed model predicted 96.3% of athletes with and without LBI. Prediction model were as follows: predict lower extremity long bone stress injury = 23.465 - 0.896 BMI + 1.043 (total upper-body mass) TUB - 34.536 leg bone mineral density (BMD). Predict lower extremity long bone stress injury is the LBI prediction, and TUB (kg) is total fat, muscle, and bone weight in trunk and arms.

CONCLUSIONS

These preliminary data suggest that Division 1 white male endurance running athletes are at risk of LBI with higher relative TUB and lower BMI in combination with a lower leg BMD.

Effects of Dietary Protein on Body Composition in Exercising Individuals

Protein is an important component of a healthy diet and appears to be integral to enhancing training adaptations in exercising individuals. The purpose of this narrative review is to provide an evidence-based assessment of the current literature examining increases in dietary protein intake above the recommended dietary allowance (RDA: 0.8 g/kg/d) in conjunction with chronic exercise on body composition (i.e., muscle, fat and bone). We also highlight acute and chronic pre-sleep protein studies as well as the influence of exercise timing on body composition. Overall, a high-protein diet appears to increase muscle accretion and fat loss and may have beneficial effects on bone when combined with exercise. Pre-sleep protein is a viable strategy to help achieve total daily protein goals. Importantly, there appears to be no deleterious effects from a high-protein diet on muscle, fat or bone in exercising individuals.

Body composition differences by age and playing standard in male rugby union and rugby league: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to determine differences in body compositionn between playing standard and age in male rugby union and rugby league athletes. The MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines for design, implementation, and reporting were followed. Studies were required to be in male rugby union or league and have body composition as the primary or secondary outcome. Data was required to be presented separately for positional groups and body composition presented as whole-body. A systematic search was performed in PubMed, Cochrane Library, MEDLINE, SPORTDiscus, and CINHAHL via EBSCOhost. 57 studies were included for meta-analysis. Results highlighted significantly higher fat-free mass in senior elite than senior sub-elite or junior elite athletes for all RU and RL forwards. Small and non-significant differences were found in fat mass between rugby union playing standards and age categories. Rugby league senior elite forwards had less fat mass than junior elite forwards. Practitioners should prioritise training and nutritional strategies that maximise fat-free mass development, especially in junior elite cohorts.

Post-exercise carbohydrate and energy availability induce independent effects on skeletal muscle cell signalling and bone turnover: implications for training adaptation

KEY POINTS

Reduced carbohydrate (CHO) availability before and after exercise may augment endurance training-induced adaptations of human skeletal muscle, as mediated via modulation of cell signalling pathways. However, it is not known whether such responses are mediated by CHO restriction, energy restriction or a combination of both. In recovery from a twice per day training protocol where muscle glycogen concentration is maintained within 200-350 mmol kg^-1 dry weight (dw), we demonstrate that acute post-exercise CHO and energy restriction (i.e. < 24 h) does not potentiate potent cell signalling pathways that regulate hallmark adaptations associated with endurance training. In contrast, consuming CHO before, during and after an acute training session attenuated markers of bone resorption, effects that are independent of energy availability. Whilst the enhanced muscle adaptations associated with CHO restriction may be regulated by absolute muscle glycogen concentration, the acute within-day fluctuations in CHO availability inherent to twice per day training may have chronic implications for bone turnover.

ABSTRACT

We examined the effects of post-exercise carbohydrate (CHO) and energy availability (EA) on potent skeletal muscle cell signalling pathways (regulating mitochondrial biogenesis and lipid metabolism) and indicators of bone metabolism. In a repeated measures design, nine males completed a morning (AM) and afternoon (PM) high-intensity interval (HIT) (8 × 5 min at 85% V ̇ O 2 peak ) running protocol (interspersed by 3.5 h) under dietary conditions of (1) high CHO availability (HCHO: CHO ∼12 g kg^-1 , EA∼ 60 kcal kg^-1 fat free mass (FFM)), (2) reduced CHO but high fat availability (LCHF: CHO ∼3 (^-1 , EA∼ 60 kcal kg^-1 FFM) or (3), reduced CHO and reduced energy availability (LCAL: CHO ∼3 g kg^-1 , EA∼ 20 kcal kg^-1 FFM). Muscle glycogen was reduced to ∼200 mmol kg^-1  dw in all trials immediately post PM HIT (P < 0.01) and remained lower at 17 h (171, 194 and 316 mmol kg^-1  dw) post PM HIT in LCHF and LCAL (P < 0.001) compared to HCHO. Exercise induced comparable p38MAPK phosphorylation (P < 0.05) immediately post PM HIT and similar mRNA expression (all P < 0.05) of PGC-1α, p53 and CPT1 mRNA in HCHO, LCHF and LCAL. Post-exercise circulating βCTX was lower in HCHO (P < 0.05) compared to LCHF and LCAL whereas exercise-induced increases in IL-6 were larger in LCAL (P < 0.05) compared to LCHF and HCHO. In conditions where glycogen concentration is maintained within 200-350 mmol kg^-1  dw, we conclude post-exercise CHO and energy restriction (i.e. < 24 h) does not potentiate cell signalling pathways that regulate hallmark adaptations associated with endurance training. In contrast, consuming CHO before, during and after HIT running attenuates bone resorption, effects that are independent of energy availability and circulating IL-6.

Bone mineral density, energy availability, and dietary restraint in collegiate cross-country runners and non-running controls

PURPOSE

Weight-bearing activities such as running have been shown to be osteogenic. However, investigations have also shown that running may lead to site-specific deficiencies in bone mineral density (BMD) as well as overall low BMD. The purpose of this investigation was to evaluate and compare the BMD of female and male collegiate cross-country runners with non-running controls. In addition, energy availability and disordered eating attitudes and behaviors were assessed.

METHODS

BMD of 60 collegiate cross-country runners and 47 BMI and age-matched non-running controls were measured via DXA scans. Participants completed a Block 2014 Food Frequency Questionnaire and Eating Disorder Examination Questionnaire.

RESULTS

Controlling for fat-free mass (FFM), male runners showed greater BMD at the femoral neck (0.934 ± 0.029 vs. 0.866 ± 0.028 g cm2, p < 0.05), total hip (1.119 ± 0.023 vs. 1.038 ± 0.021 g cm2, p < 0.05), and whole body (1.119 ± 0.023 vs. 1.038 ± 0.021 g cm2, p < 0.05) than male controls. The female runners had greater whole-body BMD than female controls (1.143 ± 0.018 vs. 1.087 ± 0.022 g cm2, p < 0.05). Runners scored significantly higher than controls in dietary restraint (1.134 ± 1.24 vs. 0.451 ± 0.75, p < 0.05), male runners were significantly higher than male controls in eating concern (1.344 ± 1.08 vs. 0.113 ± 0.27, p < 0.05) and female runners were significantly higher than male runners in shape concern (1.056 ± 1.27 vs. 0.242 ± 0.31, p < 0.05). Forty-two percent of the male runners and 29% of female runners had an energy availability of less than 30 kcals kg-1FFM.

CONCLUSION

It appears that distance running has beneficial effects on whole-body BMD and site-specific areas. Further research is warranted to further clarify the health effects of eating behaviors and EA of distance runners.

Sport and Triad Risk Factors Influence Bone Mineral Density in Collegiate Athletes

PURPOSE

Athletes in weight-bearing sports may benefit from higher bone mineral density (BMD). However, some athletes are at risk for impaired BMD with female athlete triad (Triad). The purpose of this study is to understand the influence of sports participation and Triad on BMD. We hypothesize that athletes in high-impact and multidirectional loading sports will have highest BMD, whereas nonimpact and low-impact sports will have lowest BMD. Triad risk factors are expected to reduce BMD values independent of sports participation.

METHODS

Two hundred thirty-nine female athletes participating in 16 collegiate sports completed dual-energy x-ray absorptiometry (DXA) scans to measure BMD z-scores of the lumbar spine (LS) and total body (TB). Height and weight were measured to calculate body mass index (BMI). Triad risk assessment variables were obtained from preparticipation examination. Mean BMD z-scores were compared between sports and by sport category (high-impact, multidirectional, low-impact, and nonimpact). Multivariable regression analyses were performed to identify differences of BMD z-scores accounting for Triad and body size/composition.

RESULTS

Athlete populations with lowest average BMD z-scores included synchronized swimming (LS, -0.34; TB, 0.21) swimming/diving (LS, 0.34; TB, -0.06), crew/rowing (LS, 0.27; TB, 0.62), and cross-country (LS, 0.29; TB, 0.91). Highest values were in gymnastics (LS, 1.96; TB, 1.37), volleyball (LS, 1.90; TB, 1.74), basketball (LS, 1.73; TB, 1.99), and softball (LS, 1.68; TB, 1.78). All Triad risk factors were associated with lower BMD z-scores in univariable analyses; only low BMI and oligomenorrhea/amenorrhea were associated in multivariable analyses (all P < 0.05). Accounting for Triad risk factors and body size/composition, high-impact sports were associated with higher LS and TB BMD z-scores and nonimpact sports with lower LS and TB BMD z-scores compared to low-impact sport (all P < 0.05).

CONCLUSIONS

Both sport type and Triad risk factors influence BMD. Athletes in low-impact and nonimpact sports and athletes with low BMI and oligomenorrhea/amenorrhea are at highest risk for reduced BMD.

Dominant vs. non-dominant hip comparison in bone mineral density in young sporting athletes

To explore differences in bone mineral density (BMD) between dominant and non-dominant hip within levels of sport impact. BMD was higher in the non-dominant hip in high-impact sports, whereas the dominant hip had increased BMD for low-impact sports. The side-to-side differences were relatively small and not clinically relevant.

PURPOSE

It is unknown whether there is difference in BMD at the hip between dominant and non-dominant sides in young athletes. The aims of this study were to explore the dominant-non-dominant differences in hip BMD in young athletes participating in low- and high-impact sports and to assess the effect of ground force impact on BMD.

METHODS

Data was collected on University of Oxford athletes and controls (CG) between 2016 and 2018. Athletes were classified into two groups: high-impact sports (HIG) and low-impact sports (LIG). Total and regional measurements of both hips' BMD were recorded using a dual-energy X-ray absorptiometry (DXA). Linear regression method was used to assess differences in BMD between and within groups.

RESULTS

One hundred ninety-four athletes (HIG: n = 89, LIG: n = 105) and 48 controls were included in this study. Total hip and femoral neck BMD was higher in athletes compared to the CG (p < 0.01), with HIG recording highest levels of BMD. The BMD difference between the dominant and non-dominant sides was significant in the LIG, with BMD being higher in the dominant side. Conversly, BMD was higher in the non-dominant hip within the HIG. However, the hip asymmetries were not clinically relevant (%BMD difference < 3%). A significant interaction between side and sport group on BMD was observed.

CONCLUSIONS

High-impact sports had significantly higher BMD compared with low-impact sports and CG. BMD in the dominant hip was significantly higher for the LIG and lower in the HIG; however, differences were not clinically relevant.

Effects of Strength Training on Body Composition in Young Male Professional Soccer Players

The present prospective cohort study investigated changes in body composition (BC) in young male football players (n = 18, 16.1 ± 0.8 years; 181.0 ± 0.1 cm; 71.3 ± 4.9 kg) after combined football and strength training (ST) during a whole in-season period (26 weeks). BC was measured at whole-body absolute and regional levels by dual-energy X-ray absorptiometry in eighteen players at the beginning and at the end of the competitive period. The ST was organized into three different session types: ST in the gym, specific ST on the field, and individual ST (weak points). The results of the present study indicated that fat-free mass (FFM) was substantially higher following the competitive period (5.1% ± 1.2%), while percentage of fat showed no changes during the competitive period. At the regional level, arms’ and legs’ FFM increased at the end of the season, and bone mineral content (BMC) and density (BMD) increased in arms, legs, pelvis, thoracic spine, and lumbar spine. In conclusion, within the limitation of the potential positive impact of growth and/or maturation, present results seem to indicate that an ST program that supplements football-related training sessions could be an effective option to increase FFM, BMC, and BMD at both whole-body and regional level across the competitive season in young male professional football players.

Nutrition for the Prevention and Treatment of Injuries in Track and Field Athletes

Injuries are an inevitable consequence of athletic performance with most athletes sustaining one or more during their athletic careers. As many as one in 12 athletes incur an injury during international competitions, many of which result in time lost from training and competition. Injuries to skeletal muscle account for over 40% of all injuries, with the lower leg being the predominant site of injury. Other common injuries include fractures, especially stress fractures in athletes with low energy availability, and injuries to tendons and ligaments, especially those involved in high-impact sports, such as jumping. Given the high prevalence of injury, it is not surprising that there has been a great deal of interest in factors that may reduce the risk of injury, or decrease the recovery time if an injury should occur: One of the main variables explored is nutrition. This review investigates the evidence around various nutrition strategies, including macro- and micronutrients, as well as total energy intake, to reduce the risk of injury and improve recovery time, focusing upon injuries to skeletal muscle, bone, tendons, and ligaments.

The effect of running on foot muscles and bones: A systematic review

Despite the widespread evidence of running as a health-preserving exercise, little is known concerning its effect on the foot musculature and bones. While running may influence anatomical foot adaptation, it remains unclear to what extent these adaptations occur. The aim of this paper is to provide a systematic review of the studies that investigated the effects of running and the adaptations that occur in foot muscles and bones. The search was performed following the PRISMA guidelines. Relevant keywords were used for the search through PubMed/MEDLINE, Scopus and SPORTDiscus. The methodological quality of intervention studies was assessed using the Downs and Black checklist. For cross-sectional studies, the Newcastle-Ottawa scale was used. Sixteen studies were found meeting the inclusion criteria. In general, the included studies were deemed to be of moderate methodological quality. Although results of relevant literature are limited and somewhat contradictory, the outcome suggests that running may increase foot muscle volume, muscle cross-sectional area and bone density, but this seems to depend on training volume and experience. Future studies conducted in this area should aim for a standard way of reporting foot muscle/bone characteristics. Also, herein, suggestions for future research are provided.

Bone stress injuries in male distance runners: higher modified Female Athlete Triad Cumulative Risk Assessment scores predict increased rates of injury

OBJECTIVES

Bone stress injuries (BSI) are common in runners of both sexes. The purpose of this study was to determine if a modified Female Athlete Triad Cumulative Risk Assessment tool would predict BSI in male distance runners.

METHODS

156 male runners at two collegiate programmes were studied using mixed retrospective and prospective design for a total of 7 years. Point values were assigned using risk assessment categories including low energy availability, low body mass index (BMI), low bone mineral density (BMD) and prior BSI. The outcome was subsequent development of BSI. Statistical models used a mixed effects Poisson regression model with p<0.05 as threshold for significance. Two regression analyses were performed: (1) baseline risk factors as the independent variable; and (2) annual change in risk factors (longitudinal data) as the independent variable.

RESULTS

42/156 runners (27%) sustained 61 BSIs over an average 1.9 years of follow-up. In the baseline risk factor model, each 1 point increase in prior BSI score was associated with a 57% increased risk for prospective BSI (p=0.0042) and each 1 point increase in cumulative risk score was associated with a 37% increase in prospective BSI risk (p=0.0079). In the longitudinal model, each 1 point increase in cumulative risk score was associated with a 27% increase in prospective BSI risk (p=0.05). BMI (rate ratio (RR)=1.91, p=0.11) and BMD (RR=1.58, p=0.19) risk scores were not associated with BSI.

CONCLUSION

A modified cumulative risk assessment tool may help identify male runners at elevated risk for BSI. Identifying risk factors may guide treatment and prevention strategies.

Vitamin D and the Athlete: Current Perspectives and New Challenges

The last decade has seen a dramatic increase in general interest in and research into vitamin D, with many athletes now taking vitamin D supplements as part of their everyday dietary regimen. The most recognized role of vitamin D is its regulation of calcium homeostasis; there is a strong relationship between vitamin D and bone health in non-athletic individuals. In contrast, data have consistently failed to demonstrate any relationship between serum 25[OH]D and bone health, which may in part be due to the osteogenic stimulus of exercise. Vitamin D may interact with extra-skeletal tissues such as muscle and the immune system to modulate recovery from damaging exercise and infection risk. Given that many athletes now engage in supplementation, often consuming extreme doses of vitamin D, it is important to assess whether excessive vitamin D can be detrimental to health. It has been argued that toxic effects only occur when serum 25[OH]D concentrations are greater than 180 nmol·l^-1, but data from our laboratory have suggested high-dose supplementation could be problematic. Finally, there is a paradoxical relationship between serum 25[OH]D concentration, ethnicity, and markers of bone health: Black athletes often present with low serum 25[OH]D without physiological consequences. One explanation for this could be genetic differences in vitamin D binding protein due to ethnicity, resulting in greater concentrations of bioavailable (or free) vitamin D in some ethnic groups. In the absence of any pathology, screening may be unnecessary and could result in incorrect supplementation. Data must now be re-examined, taking into consideration bioavailable or "free" vitamin D in ethnically diverse groups to enable new thresholds and target concentrations to be established; perhaps, for now, it is time to "set vitamin D free".

Treating exercise-associated low testosterone and its related symptoms

The Exercise-Hypogonadal Male Condition (EHMC) has been described to occur in athletes who experience low serum testosterone and associated symptoms. While high volumes of endurance exercise can lead to reduced testosterone concentrations in men, similar changes may occur in other sports including anerobic and power sports such as American football, and weight class sports such as wrestling. A reduced testosterone concentration alone does not necessarily warrant treatment, but when it is accompanied by symptoms of hypogonadism, such as fatigue, sexual dysfunction, and/or low bone mineral density (BMD), an athlete's performance and/or health may suffer. While pharmacological treatments such as testosterone or clomiphene citrate have been shown to be effective in treating hypogonadism, these options are not available to athletes competing in sports governed by the World Anti-Doping Agency. We recommend treatment of EHMC in athletes should include nutritional intervention and modification of training. Recognizing EHMC's existence in male athletes is important to optimize their health.

In-season eccentric-overload training in elite soccer players: Effects on body composition, strength and sprint performance

The aim of this study was to describe the changes in body composition, strength and sprint performance in response to an entire competitive season of football training supplemented with 2 inertial eccentric-overload training sessions a week in young male professional soccer players. Whole body and regional composition (assessed using dual-energy X-ray absorptiometry), power output in half-squat and 40-m sprinting performance were evaluated in fourteen players. The eccentric-overload training consisted of training sessions a week of 1–2 sets of 10 exercises of upper-body and core (Day 1) and lower-body (Day 2), during the entire competitive season (27 weeks). Whole body fat mass decreased (-6.3 ± 3.6%, ES = -0.99 ± 0.54) substantially while lean mass increased (2.5 ± 0.8%, ES = 0.25 ± 0.09), with some regional differences. There was a substantial increase in half-squat power output (from 3% to 14%, ES from 0.45 to 1.73) and sprint performance (from 1.1% to 1.8%, ES from -0.33 to -0.44), however performance changes were not correlated with changes in body composition. A combined soccer and eccentric-overload training program was able to promote positive changes in body composition and physical factors relevant to both on-field performance and injury prevention in elite soccer players.

P2X7, a critical regulator and potential target for bone and joint diseases

Abundant evidence indicted that P2X7 receptor show a essential role in human health and some human diseases including hypertension, atherosclerosis, pulmonary inflammation, tuberculosis infection, psychiatric disorders, and cancer. P2X7 receptor also has an important role in some central nervous system diseases such as neurodegenerative disorders. Recently, more research suggested that P2X7 receptor also plays a crucial role in bone and joint diseases. But the effect of P2X7 receptor on skeletal and joint diseases has not been systematically reviewed. In this article, the role of P2X7 receptor in skeletal and joint diseases is elaborated. The activation of P2X7 receptor can ameliorate osteoporosis by inducing a fine balance between osteoclastic resorption and osteoblastic bone formation. The activation of P2X7 receptor can relieve the stress fracture injury by increasing the response to mechanical loading and inducing osteogenesis. But the activation of P2X7 receptor mediates the cell growth and cell proliferation in bone cancer. In addition, the activation of P2X7 receptor can aggravate the process of some joint diseases such as osteoarthritis, rheumatoid arthritis, and acute gouty arthritis. The inhibition of P2X7 receptor can alleviate the pathological process of joint disease to some extent. In conclusion, P2X7 receptor may be a critical regulator and therapeutic target for bone and joint diseases.

Relative Energy Deficiency in Sport in Male Athletes: A Commentary on Its Presentation Among Selected Groups of Male Athletes

Low energy availability (LEA) is a key element of the Female Athlete Triad. Causes of LEA include failure to match high exercise energy expenditure (unintentional) or pathological behaviors of disordered eating (compulsive) and overzealous weight control programs (misguided but intentional). Recognition of such scenarios in male athletes contributed to the pronouncement of the more inclusive Relative Energy Deficiency in Sport (RED-S) syndrome. This commentary describes the insights and experience of the current group of authors around the apparently heightened risk of LEA in some populations of male athletes: road cyclists, rowers (lightweight and open weight), athletes in combat sports, distance runners, and jockeys. The frequency, duration, and magnitude of the LEA state appear to vary between populations. Common risk factors include cyclical management of challenging body mass and composition targets (including "making weight") and the high energy cost of some training programs or events that is not easily matched by energy intake. However, additional factors such as food insecurity and lack of finances may also contribute to impaired nutrition in some populations. Collectively, these insights substantiate the concept of RED-S in male athletes and suggest that a specific understanding of a sport, subpopulation, or culture may identify a complex series of factors that can contribute to LEA and the type and severity of its outcomes. This commentary provides a perspective on the range of risk factors that should be addressed in future surveys of RED-S in athletic populations and targeted for specific investigation and modification.