Bone status in professional cyclists

Bone mineral density varies throughout the skeleton of athletes dependent on their sport: Allometric modelling identifies the "effective" forces associated with body mass

OBJECTIVES

Bone mineral density (BMD) varies throughout the skeleton with the differences influenced by the type of sport, body mass and participant's age. What is not so well understood is how body mass influences BMD across different sites.

DESIGN

Proportional allometric modelling on cross-sectional data.

METHODS

Male athletes (n = 106) from 8 different athletic groups and controls (n = 15) were scanned by dual X-ray absorptiometry (DXA) and analysed for total body composition and BMD of the ribs, arms, thoracic spine, lumber spine, pelvis and legs.

RESULTS

ANOVA identified significant differences in BMD between "sites", "sports" and site-by-sport interaction (all p < 0.001). By introducing body mass and age as covariates, the "sites" differences disappeared. The explanation is due to the systematic difference in body-mass exponents (ki), with lowest positioned sites (e.g. legs) having the steepest slopes, and the elevated sites (e.g. arms having the shallowest slopes). To illustrate, the arm-mass exponent was approximately 0.33 indicating that for a 75 kg male, arm BMD responds to forces associated with body mass = (75)0.33 = 5 kg. For the same individual, the leg-mass exponent was closer to 0.66 suggesting that leg BMD responds to forces associated with body mass = (75)0.66 = 25 kg.

CONCLUSIONS

The model for BMD identified that [Formula: see text] plays a crucial role in determining the effective forces (both gravitational/ground reaction and compressional forces) operating throughout the skeleton, where ki systematically increases where the lower the bone is situated, a mechanism that also explains why activities involving running benefit the leg BMD compared with weight-supported activities (e.g., rowing).

The relationship between bone parameters, body composition, and lower extremity strength in road cyclists

BACKGROUND

This study aimed to compare the relationships between bone and body composition parameters, and isometric maximal voluntary contraction (MVC) force of knee extensor (KE) muscles in road cyclists and untrained controls.

METHODS

Twelve male road cyclists and 12 controls aged 20-34 years participated. The isometric MVC force of the KE muscles was assessed by a custom-made dynamometer. Bone mineral content (BMC), bone mineral density (BMD), and body composition were assessed using Dual-Energy X-ray Absorptiometry.

RESULTS

No differences were found in body mass, lean body mass, leg lean mass, MVC, whole body, and leg BMD and BMC between cyclists and controls. Controls had a significantly greater (P<0.001) body mass index (BMI), whole body (P<0.01), and leg fat (P<0.001) mass than athletes. In road cyclists, BMC correlated positively with body mass (r=0.73; P<0.01) and BMI (r=0.65; P<0.05), body (r=0.85; P<0.001) and leg lean mass (r=0.81; P<0.001); BMD correlated positively with lean body mass (r=0.60; P<0.05), leg lean mass (r=0.65 and r=0.60; P<0.05). MVC of KE muscles correlated positively with bone parameters (P<0.01) and lean mass (P<0.05) only in controls.

CONCLUSIONS

Regular cycling training was associated with lower BMI, and body and leg fat mass. There were no significant differences in bone parameters, body and leg lean mass, and isometric MVC force of KE muscle variables between road cyclists and controls. In road cyclists, bone parameters are associated with body mass, and body and leg lean mass, but not with the isometric strength of KE muscles.

Low Bone Mineral Density and Associated Risk Factors in Elite Cyclists at Different Stages of a Professional Cycling Career

PURPOSE

This study aimed to assess the prevalence of low bone mineral density (BMD) in male and female elite cyclists at different stages of a professional cycling career and to identify potential risk factors of low BMD.

METHODS

In this cross-sectional study, 93 male and female early career, advanced career, and postcareer elite cyclists completed dual-energy x-ray absorptiometry at the hip, femoral neck, lumbar spine, and total body; blood sampling; assessment of training history and injuries; and the bone-specific physical activity questionnaire. Backward stepwise multiple regression analyses were conducted to explore associations between BMD and its potential predictors in early and advanced career (i.e., active career) cyclists.

RESULTS

With a mean Z -score of -0.3 ± 0.8, -1.5 ± 1.0, and -1.0 ± 0.9, low BMD ( Z -score < -1) at the lumbar spine was present in 27%, 64%, and 50% of the early, advanced, and postcareer elite male cyclists, respectively. Lumbar spine Z -scores of -0.9 ± 1.0, -1.0 ± 1.0, and 0.2 ± 1.4 in early, advanced, and postcareer elite female cyclists, respectively, indicated low BMD in 45%, 45%, and 20% of these female subpopulations. Regression analyses identified body mass index, fracture incidence, bone-specific physical activity, and triiodothyronine as the main factors associated with BMD.

CONCLUSIONS

Low BMD is highly prevalent in elite cyclists, especially in early career females and advanced career males and females. These low BMD values may not fully recover after the professional cycling career, given the substantial prevalence of low BMD in retired elite cyclists. Exploratory analyses indicated that low BMD is associated with low body mass index, fracture incidence, lack of bone-specific physical activity, and low energy availability in active career elite cyclists.

Patterns of energy availability of free-living athletes display day-to-day variability that is not reflected in laboratory-based protocols: Insights from elite male road cyclists

The physiological effects of low energy availability (EA) have been studied using a homogenous daily EA pattern in laboratory settings. However, whether this daily EA pattern represents those of free-living athletes and is therefore ecologically valid is unknown. To investigate this, we assessed daily exercise energy expenditure, energy intake and EA in 10 free-living elite male road cyclists (20 min Mean Maximal Power: 5.27 ± 0.25 W · kg^-1) during 7 consecutive days of late pre-season training. Energy intake was measured using the remote-food photography method and exercise energy expenditure estimated from cycling crank-based power-metres. Seven-day mean ± SD energy intake and exercise energy expenditure was 57.9 ± 10.4 and 38.4 ± 8.6 kcal · kg FFM^-1 · day^-1, respectively. EA was 19.5 ± 9.1 kcal · kg FFM^-1 · day^-1. Within-participants correlation between daily energy intake and exercise energy expenditure was .62 (95% CI: .43 - .75; P < .001), and .60 (95% CI: .41 - .74; P < .001) between carbohydrate intake and exercise energy expenditure. However, energy intake only partially compensated for exercise energy expenditure, increasing 210 kcal · day^-1 per 1000 kcal · day^-1 increase in expenditure. EA patterns displayed marked day-to-day fluctuation (range: -22 to 76 kcal · kg FFM^-1 · day^-1). The validity of research using homogenous low EA patterns therefore requires further investigation.

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.

Assessment of Dietary Intake and Nutritional Status in CrossFit-Trained Individuals: A Descriptive Study

CrossFit is a discipline with high training and nutritional requirements. To date, there is only scarce data evaluating nutrition among CrossFit training and they mostly focus on selected nutritional interventions. Therefore, the purpose of this descriptive study was the assessment of dietary intake and nutritional status in a selected group of CrossFit-trained participants. The study consisted of 62 CrossFit athletes (31 men and 31 women, aged 31.0 ± 5.2 and 30.0 ± 4.3 years, respectively). Body composition was analyzed by electrical bioimpedance. Dietary intake was assessed using a standardized 3-day food record. Body fat percentage for females and males was 20.3 ± 4.3% and 13.7 ± 3.3% respectively. The energy intake in the diet was lower (~1700 kcal in women and ~2300 kcal in men) than the recommended demand. Moreover, low consumption of carbohydrates was stated, as well as an inadequate intake of folate, vitamin E (in women), and minerals, such as Fe and Ca (in women). The energy, carbohydrate, iron, and calcium intake in the CrossFit participants' diet was too low in comparison to recommendations. It seems justified to educate athletes and coaches about nutritional habits, and individual energy and nutrients requirements.

The effects of a 226-km ironman triathlon race on bone turnover in amateur male triathletes

BACKGROUND

The purpose of this study was to investigate the effects of an Ironman-distance triathlon on bone metabolism.

METHODS

Nine recreational male triathletes (39.7±8.2 years old) were voluntarily recruited before a 226-km Ironman triathlon race. Baseline blood samples were collected >1 hour before race. Serial post-race blood sampling time points included immediately (0hr), 1 hour (1hr), 1 day (d), 3 d, and 5 d after the Ironman race.

RESULTS

Serum muscle damage markers, serum myoglobin, creatine kinase (CK) and lactate dehydrogenase (LDH) revealed significant post-race peak values immediately, 1hr and 1d after the race, respectively. Except for the marginally higher serum CK and myoglobin at 5d (P=0.01~0.05), all post-race serum levels of muscle damage markers were significantly higher than baseline levels (P<0.01). Serum phosphorus values were significantly higher immediately (0hr) after the Ironman race. Serum osteocalcin, an index specific to bone formation, showed a significant decrease at time points 0hr and 1hr, but a significant increase 1 day after (P<0.01) and a marginal increase 3 and 5 days after (P=0.01~0.05) the race. No difference was shown in type I collagen C-telopeptide (CTX-1), a bone resorption marker. Pearson's correlation between serum osteocalcin and CTX-1 was done at each time point, and significant correlation was shown on the 5th d after the race (r=0.591, P<0.05).

CONCLUSIONS

An Ironman-distance contest induces a bone-formative-favoring turnover during the post-race period for amateur male triathletes.

Bone mineral density and lean mass asymmetries are greater in cyclists than non-cyclists

Cyclists may be at greater risk of developing asymmetrical force and motion patterns than other ground-based athletes. However, functional asymmetries during cycling tend to be highly variable, making them difficult to assess. Dual-energy x-ray absorptiometry (DXA) measurements of areal bone mineral density (aBMD) and lean mass (LM) in the lower limbs may be a more sensitive and consistent method to identify asymmetries in cyclists. The goal of this study was to determine if competitive cyclists have greater levels of asymmetries in the lower body compared to non-cyclists using DXA. A secondary aim was to determine if aBMD and LM asymmetries change over the road cycling season. 17 competitive cyclists and 21 non-cyclist, healthy controls underwent DXA scans. Lower-body asymmetries were greater in cyclists compared to non-cyclists in aBMD and LM for all lower limb segments. However, these asymmetries did not tend to consistently favour a particular side, except for the pelvis having more LM on the dominant side. The were no longitudinal changes in aBMD or LM in the cyclists. Asymmetry analysis via DXA provides evidence that although functional asymmetries during cycling are variable, cyclists have increased lower body LM and aBMD asymmetries compared to non-cyclists.

Effect of 7 Months of Physical Training and Military Routine on the Bone Mass of Young Adults

INTRODUCTION

Physical activity (PA) has a great influence on bone mineral density (BMD) and bone mineral content (BMC), however longitudinal studies that seek to relate bone mass to physical activity are scarce and have a small sample size. The aim of this study was to evaluate and compare the effect of 7 months of military physical training (MPT), impact sports (IS), and swimming in the bone mass of young military adults.

MATERIALS AND METHODS

A prospective study was conducted with 213 military school students (male and aged 19.2 ± 1.2 years) divided into three groups: MPT (n = 144), IS (n = 56), and Swimming (n = 13). Dual-energy X-ray absorptiometry was used to determine body composition (percentage of fat, fat mass, and fat-free mass) and bone mass (BMD, BMD Z-Score, total BMC, arm BMC, leg BMC, and trunk BMC), at the beginning of the military service and after 7 months of training.

RESULTS

It was observed a significant increase in BMD, BMD Z-Score, total BMC and BMC of all segments analyzed for all groups (p < 0.01). There was a significantly greater variation in BMD of the IS group in relation to the MPT group (p < 0.01), and in the arm BMC of the MPT group in relation to the IS group (p < 0.05).

CONCLUSION

After 7 months of training, there were significant increases in BMC and BMD of all the groups evaluated. The bone response was associated with the muscular group used in the physical exercise and the IS group showed greater gain in BMD.

Exercise dependence, eating disorder symptoms and biomarkers of Relative Energy Deficiency in Sports (RED-S) among male endurance athletes

Objectives

To explore associations betweenexercise dependence, eating disorder (ED) symptoms and biomarkers of Relative Energy Deficiency in Sports (RED-S) among male endurance athletes.

Methods

Fifty-three healthy well-trained male cyclists, triathletes and long-distance runners recruited from regional competitive sports clubs were included in this cross-sectional study. The protocol comprised the Exercise Dependence Scale (EXDS), the ED Examination Questionnaire (EDE-Q), measurements of body composition, resting metabolic rate, energy intake and expenditure and blood analysis of hormones and glucose.

Results

Participants with higher EXDS score displayed a more negative energy balance compared with subjects with lower EXDS score (p<0.01). EXDS total score was positively correlated with EDE-Q global score (r=0.41, p<0.05) and the subscale score for restraint eating (r=0.34, p<0.05) and weight concern (r=0.35, p<0.05). EXDS total score and the subscales lack of control and tolerance were positively correlated with cortisol (r=0.38, p<0.01, r=0.39, p<0.01 and r=0.29, p<0.05, respectively). The EXDS subscales withdrawal and tolerance were negatively correlated with fasting blood glucose (r=-0.31 and r=-0.32, p<0.05, respectively), while intention effect was negatively correlated with testosterone:cortisol ratio (r=-0.29, p<0.05) and positively correlated with cortisol:insulin ratio (r=0.33, p<0.05).

Conclusion

In this sample of healthy male athletes, we found associations between higher EXDS scores, ED symptoms and biomarkers of RED-S, such as a more pronounced negative energy balance and higher cortisol levels.

Bone health in elite Norwegian endurance cyclists and runners: a cross-sectional study

Background

Athletes who compete in non-weight-bearing activities such as swimming and cycling are at risk of developing low bone mineral density (BMD). Athletes in long-distance running are at risk of low BMD.

Objective

(1) To evaluate the bone health in Norwegian male and female national elite road cyclists and middle-distance and long-distance runners, and to identify cases of low BMD. (2) To identify possible risk factors associated with low BMD.

Methods

Twenty-one runners (11 females and 10 males) and 19 road cyclists (7 females and 12 males) were enrolled in this cross-sectional study. Dual-energy X-ray absorptiometry measurement of BMD in total body, femoral neck and lumbar spine was measured. Participants completed a questionnaire regarding training, injuries, calcium intake and health variables.

Results

The cyclists had lower BMD for all measured sites compared with the runners (p≤0.05). Ten of 19 cyclists were classified as having low BMD according to American College of Sports Medicine criteria (Z-score ≤−1), despite reporting to train heavy resistance training on the lower extremities. Low BMD was site specific having occurred in the lumbar spine and the femoral neck and was not confined to females. Type of sport was the only factor significantly associated with low BMD.

Conclusion

National elite Norwegian road cyclists had lower BMD compared with runners, and a large proportion was classified as having low BMD, despite having performed heavy resistance training. Interventions to increase BMD in this population should be considered.

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.

Longitudinal Assessment of Bone Mineral Density and Body Composition in Competitive Cyclists

Baker, BS and Reiser II, RF. A longitudinal assessment of bone mineral density and body composition in competitive cyclists. J Strength Cond Res 31(11): 2969-2976, 2017-Competitive cycling has been associated with low bone mineral density (BMD); however, BMD is a multifaceted issue. The purpose of this study was to investigate how age (18-49 years), sex, USA Cycling Category (elite-4), and racing type (road and multiple bikes), influenced body composition across a season in competitive cyclists. February marked the preseason, where 42 participants (22 males, 20 females) completed a health history and cycling questionnaire, 4-day dietary log and a dual-energy X-ray absorptiometry scan, and repeated the measures 180 ± 11 days later. Preseason BMD and Z-Scores were within healthy ranges and similar between sexes, age groups, competition levels and racing-type groups (p ≥ 0.053). Age was significantly correlated with whole group BMD (r = 0.309; p = 0.047). Postseason analysis revealed very encouraging findings as no significant changes in BMD or Z-Score were observed in any group (p ≥ 0.067). A significant main effect for time was found in all groups as lean mass (LM) decreased and fat mass increased across the season (p ≤ 0.001). Additional analysis showed a significant time × group interaction as cat. 1 riders decreased body mass and body mass index, whereas cat. 4 riders responded in the opposite direction (p ≤ 0.037). Postseason correlations highlighted significant positive relationships between BMD and age, LM, and Kcal ingested (r ≥ 0.309; p ≤ 0.047). The only significant negative correlate of BMD was percent body fat (r = -0.359; p = 0.020). Armed with this information, cyclists and coaches should aim to prioritize balance between body mass and caloric intake while meeting the demands of training to minimize risk of cycling related low bone mass.

Bone Structure and Geometric Properties at the Radius and Tibia in Adolescent Endurance-Trained Cyclists

OBJECTIVE

To describe cortical and trabecular volumetric bone mineral density (vBMD), bone mineral content (BMC), cross-sectional area (CSA), and bone strength indexes (BSIs) in adolescent endurance-trained cyclists (CYC) and compare them with controls (CON).

DESIGN

Descriptive cohort study.

PARTICIPANTS

Twenty-five male adolescent CYC and 17 CON.

ASSESSMENT OF RISK FACTORS

Peripheral quantitative computed tomography was used to evaluate proximal and distal sites of the radius and tibia.

MAIN OUTCOME MEASURES

Total, trabecular, and cortical BMC, vBMD, and CSA were measured. Also, cortical thickness, endosteal and periosteal circumferences, and different BSIs were calculated. Unadjusted analysis of variance and body weight-adjusted analysis of covariance tests were applied between cyclist and control groups.

RESULTS

Cyclists were almost 12% lighter than CON (P < 0.05). Unadjusted data showed lower distal total vBMD and proximal cortical BMC and vBMD in cyclists compared with CON at the radius (P < 0.05) and lower distal total and trabecular BMC, vBMD and bone area, proximal total and cortical BMC and vBMD, and cortical bone area at the tibia (P < 0.05). Body weight-adjusted data showed the same differences for distal total vBMD at the radius and total and trabecular BMC and vBMD at the tibia, diaphyseal radius cortical vBMD and tibia total vBMD, cortical BMC and area, and also for tibia cortical thickness and BSI. The rest of differences were no longer detectable and bone area at the distal radius become significantly higher in cyclist compared with CON (P < 0.05).

CONCLUSIONS

Adolescent CYC in this study showed lower values of BMC and vBMD at determined sites of the radius and tibia than CON, some of these differences were explained in part by their lower body weight. However, even further adjustment, some differences remained, which indicates that further longitudinal studies are needed to better understand if cycling influences these differences.

Radial and tibial bone indices in athletes participating in different endurance sports: a pQCT study

Low magnitude bone-loading sports may benefit bone structure and strength in the exercised limbs. This study compared peripheral quantitative computed tomography measures of radial and tibial diaphyseal strength (strength-strain index, SSI), structure (total area (ToA) and cortical area (CoA), density (CoD) and thickness (CT), and circumferences), muscle cross-sectional area (MCSA) and strength (one-repetition maximum, 1-RM) in male endurance athletes taking part in (i) non-weight-bearing and non-impact sports: swimmers (SWIM, n = 13) and road cyclists (RC, n = 10), (ii) non-weight-bearing, impact sport: mountain bikers (MB, n = 10), (iii) weight bearing and impact sport: runners (RUN, n = 9). All athlete groups were also compared to sedentary controls (CON, n = 10). Arm MCSA, 1-RM and radial bone size and strength tended to be greater in SWIM than CON and/or RC (ToA, %difference  ± 95%CI, SWIM-CON: 14.6% ± 12.7%; SWIM-RC: 12.9% ± 10.7%) but not different to MB and RUN. RUN had bigger tibial CoA than CON, SWIM and RC (CoA, RUN-CON: 12.1% ± 10.7%; RUN-SWIM: 10.9% ± 9.4%; RUN-RC: 15.8% ± 9.5%) without marked changes in tibial strength indices, lower-limb MCSA or 1-RM. Both MB and RC failed to display any difference in tibial indices, lower-limb MCSA and 1-RM compared to CON. In swimmers, the bone structure and strength of the primary exercised limbs, the arms, is greater than controls and road cyclists. Conversely, although runners experience impact and weight-bearing loading, tibial structure is greater without a substantial difference in tibial strength compared to controls and non-impact sports. Failure to observe a difference in tibial indices in MB and RC compared to controls is unexpected.

Swimming and cycling do not cause positive effects on bone mineral density: a systematic review

Osteoporosis is considered a common metabolic bone disease and its prevalence is increasing worldwide. In this context, physical activity has been used as a non-pharmacological tool for prevention and auxiliary treatment of this disease. The aim of this systematic review was to evaluate the effects of cycling and swimming practice on bone mineral density (BMD). This research was conducted in accordance with the recommendations outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The studies were consulted in the period from 2004 to 2014, through major electronic databases: PubMed(®), SciELO(®) and LILACS(®). Ten studies evaluated the effects of cycling on BMD, and the results showed that nine studies have linked the practice of professional cycling with low levels of BMD. Another 18 studies have reported that swimming has no positive effects on bone mass. We conclude that cycling and swimming do not cause positive effects on BMD; thus, these are not the most suitable exercises for prevention and treatment of osteoporosis.

Comparisons of Bone Mineral Density Between Recreational and Trained Male Road Cyclists

OBJECTIVE

To compare measures of training, performance, body composition, and areal bone mineral density (aBMD) between age-matched recreational and competitively trained male road cyclists.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Male cyclists (N = 28) aged 21-54 years riding more than 3 hours per week.

ASSESSMENT OF RISK FACTORS

Men who train at high (≥8 h/wk) and moderate volumes (3-8 h/wk).

MAIN OUTCOME MEASURES

Areal bone mineral density assessments by dual energy x-ray absorptiometry of the whole body, lumbar spine (L1-L4), right and left hips, maximal oxygen uptake (V[Combining Dot Above]O2max), and training history.

RESULTS

Trained cyclists had higher power to weight (5.3 ± 0.4 vs 4.7 ± 0.3 W/kg, P = 0.001), V[Combining Dot Above]O2max (57.2 ± 4.5 vs 53.0 ± 6.1 mL·kg·min, P = 0.049) and training volume (10.6 ± 2.1 vs 6.3 ± 0.9 h/wk, P < 0.001) than recreational cyclists. Trained cyclists had lower right (0.898 ± 0.090 vs 0.979 ± 0.107 g/cm, P = 0.047) and left hip aBMD (0.891 ± 0.079 vs 0.973 ± 0.104 g/cm, P = 0.032). Z-scores identified lumbar (L1-L4) aBMD as osteopenic (-2.5 < Z-score < -1.0) in trained cyclists (-1.39 ± 1.09). Lumbar scans identified 12 trained and 4 recreational cyclists as osteopenic and 3 trained cyclists as osteoporotic.

CONCLUSIONS

Areal bone mineral density is lower in trained male road cyclists compared with recreational, specifically at the hips. Lumbar aBMD is low in both trained and recreational cyclists. Research is needed to determine the chronic effects of cycling on aBMD and interventions that improve aBMD in this population.

CLINICAL RELEVANCE

This study suggests road cycling may compromise aBMD and potentially increase the likelihood of low-trauma fractures; health care professionals should consider this exposure when exercise prescriptions are designed for patients at-risk for osteopenia/osteoporosis, for example, women and older adults.

Swimming and cycling do not cause positive effects on bone mineral density: a systematic review

Osteoporosis is considered a common metabolic bone disease and its prevalence is increasing worldwide. In this context, physical activity has been used as a non-pharmacological tool for prevention and auxiliary treatment of this disease. The aim of this systematic review was to evaluate the effects of cycling and swimming practice on bone mineral density (BMD). This research was conducted in accordance with the recommendations outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The studies were consulted in the period from 2004 to 2014, through major electronic databases: PubMed®, SciELO® and LILACS®. Ten studies evaluated the effects of cycling on BMD, and the results showed that nine studies have linked the practice of professional cycling with low levels of BMD. Another 18 studies have reported that swimming has no positive effects on bone mass. We conclude that cycling and swimming do not cause positive effects on BMD; thus, these are not the most suitable exercises for prevention and treatment of osteoporosis.

Low energy availability in exercising men is associated with reduced leptin and insulin but not with changes in other metabolic hormones

Low energy availability, defined as low caloric intake relative to exercise energy expenditure, has been linked to endocrine alterations frequently observed in chronically energy-deficient exercising women. Our goal was to determine the endocrine effects of low energy availability in exercising men. Six exercising men (VO2peak: 49.3 ± 2.4 ml · kg(-1) · min(-1)) underwent two conditions of low energy availability (15 kcal · kg(-1) fat-free mass [FFM] · day(-1)) and two energy-balanced conditions (40 kcal · kg(-1) FFM · day(-1)) in randomised order. During one low energy availability and one balanced condition, participants exercised to expend 15 kcal · kg(-1) FFM · day(-1); no exercise was conducted during the other two conditions. Metabolic hormones were assessed before and after each 4-day period. Following both low energy availability conditions, leptin (-53% to -56%) and insulin (-34% to -38%) were reduced (P < 0.05). Reductions in leptin and insulin were independent of whether low energy availability was attained with or without exercise (P > 0.80). Low energy availability did not significantly impact ghrelin, triiodothyronine, testosterone and IGF-1 (all P > 0.05). The observed reductions in leptin and insulin were in the same magnitude as changes previously reported in sedentary women. Further research is needed to understand why other metabolic hormones are more robust against low energy availability in exercising men than those in sedentary and exercising women.

The effects of a calcium-rich pre-exercise meal on biomarkers of calcium homeostasis in competitive female cyclists: a randomised crossover trial

Cycling is recognised as a sport in which there is a high incidence of poor bone health. Sweat calcium losses may contribute to this.

Bone loss over 1 year of training and competition in female cyclists

OBJECTIVE

To observe changes in hip, spine, and tibia bone characteristics in female cyclists over the course of 1 year of training.

DESIGN

Prospective observational study.

SETTING

Laboratory.

PARTICIPANTS

Female cyclists (n = 14) aged 26-41 years with at least 1 year of competition history and intent to compete in 10 or more races in the coming year.

ASSESSMENT OF RISK FACTORS

Women who train and compete in road cycling as their primary sport.

MAIN OUTCOME MEASURES

Total body fat-free and fat mass and lumbar spine and proximal femur areal bone mineral density (aBMD) and bone mineral content (BMC) assessments by dual-energy x-ray absorptiometry. Volumetric BMD and BMC of the tibia were measured by peripheral quantitative computed tomography at sites corresponding to 4%, 38%, 66%, and 96% of tibia length. Time points were baseline and after 12 months of training and competition.

RESULTS

Weight and body composition did not change significantly over 12 months. Total hip aBMD and BMC decreased by -1.4% ± 1.9% and -2.1% ± 2.3% (P < 0.02) and subtrochanter aBMD and BMC decreased by -2.1% ± 2.0% and -3.3% ± 3.7% (P < 0.01). There was a significant decrease in lumbar spine BMC (-1.1% ± 1.9%; P = 0.03). There were no significant bone changes in the tibia (P > 0.11).

CONCLUSIONS

Bone loss in female cyclists was site specific and similar in magnitude to losses previously reported in male cyclists. Research is needed to understand the mechanisms for bone loss in cyclists.

Differences in the contractile properties of the knee extensor and flexor muscles in professional road cyclists during the season

The purpose of this study was to establish reference values of tensiomyography (TMG) in professional road cyclists and to examine how the planned periods of the Season produce differences in the muscles: vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF), and to determine how these differences may depend on each cyclist, the assessed muscle, and the side of the body. Ten professional road cyclists (27.5 ± 5.5 years; 178.2 ± 7.8 cm; 65.6 ± 5.46 kg; 72.1 ± 3.7 ml·kg·min V[Combining Dot Above]O2; 6 ± 0.4 W·kg) were assessed by TMG, in microcycle recovery, at 2 moments of periods during the season: preparation period (PP) and competition period (CP). Student's t contrast for paired groups, Cohen's d effect sizes, and a repeated measures analysis of variance (ANOVA) was applied. We did not find significant differences (p < 0.01) between the lower limbs. The results showed a significantly large increment between the time contraction (TC) values of the PP and CP in the muscles VM (28.7 ± 5.5 vs. 40.6 ± 14.4 milliseconds; 41.4%, p < 0.05, d = 1.1), VL (28.3 ± 4.9 vs. 40.6 ± 10.2 milliseconds; 43.4%, p < 0.05, d = 1.53), and RF (35.9 ± 6.9 vs. 45.9 ± 16.2 milliseconds; 27.8%, p < 0.05, d = 0.8). Nevertheless, TC of the BF presents a significantly large decrease in the CP (35.9 ± 9.9 vs. 28.2 ± 5.2 milliseconds; -21.4%, p < 0.05, d = 0.97). Radial muscle displacement (DM) values are slightly lower during the CP, but the difference is not significant. ANOVA confirmed that these differences depend on the evaluated muscles (TC p = 0.02; DM p = 0.001) and on the cyclists (TC p = 0.001; DM p = 0.001) and does not depend on the side of the body. In conclusion, the TC values during the Season show marked differences between the knee extensors (large increased) and the knee flexor (large decreased). The DM has not changed significantly, keeping the muscular and tendon stiffness.

Comparison of anthropometric characteristics between professional triathletes and cyclists

Anthropometric characteristics of athletes are considered to be an important determinant of success in sport. The aim of the present study was to compare several anthropometric parameters and subjective characteristics of professional elite triathletes with anthropometric profiles of professional cyclists and sportive students. In total 93 volunteers (21 male and female triathletes, 26 male cyclists and as a control group 46 male and female students) participated in this study. Eight different anthropometric parameters were measured and a five-page questionnaire containing 35 general questions had to be completed. Interestingly, there were no significant differences between the arm span, the lengths of the lower limb and the circumference of waist and hip between male triathletes and cyclists. As expected, the athletes had significantly lower heart rates and lower weights as compared to the controls. Further results showed that male cyclists had a higher BMI, larger thighs and were taller as compared to the male triathletes. The present study could not evaluate specific anthropometric characteristics as predictive factors of performance in elite athletes. Thus, individual successful performance is linked to discipline and talent rather than to a specific anthropometric profile.

High-performance sports medicine

High performance sports medicine involves the medical care of athletes, who are extraordinary individuals and who are exposed to intensive physical and psychological stresses during training and competition. The physician has a broad remit and acts as a 'medical guardian' to optimise health while minimising risks. This review describes this interesting field of medicine, its unique challenges and priorities for the physician in delivering best healthcare.

Cycling and bone health: a systematic review

BACKGROUND

Cycling is considered to be a highly beneficial sport for significantly enhancing cardiovascular fitness in individuals, yet studies show little or no corresponding improvements in bone mass.

METHODS

A scientific literature search on studies discussing bone mass and bone metabolism in cyclists was performed to collect all relevant published material up to April 2012. Descriptive, cross-sectional, longitudinal and interventional studies were all reviewed. Inclusion criteria were met by 31 studies.

RESULTS

Heterogeneous studies in terms of gender, age, data source, group of comparison, cycling level or modality practiced among others factors showed minor but important differences in results. Despite some controversial results, it has been observed that adult road cyclists participating in regular training have low bone mineral density in key regions (for example, lumbar spine). Conversely, other types of cycling (such as mountain biking), or combination with other sports could reduce this unsafe effect. These results cannot yet be explained by differences in dietary patterns or endocrine factors.

CONCLUSIONS

From our comprehensive survey of the current available literature it can be concluded that road cycling does not appear to confer any significant osteogenic benefit. The cause of this may be related to spending long hours in a weight-supported position on the bike in combination with the necessary enforced recovery time that involves a large amount of time sitting or lying supine, especially at the competitive level.

Bone and energy metabolism parameters in professional cyclists during the Giro d'Italia 3-weeks stage race

Cycling is a not weight-bearing activity and is known to induce bone resorption. Stage races are really strenuous endurance performances affecting the energy homeostasis. The recently highlighted link, in the co-regulation of bone and energy metabolism, demonstrates a central role for the equilibrium between carboxylated and undercarboxylated forms of osteocalcin. Aim of this study was to understand the acute physiological responses to a cycling stage race in terms of bone turnover and energy metabolism and the possible co-regulative mechanisms underlying their relationship. We studied nine professional cyclists engaged in 2011 Giro d'Italia stage race. Pre-analytical and analytical phases tightly followed academic and anti-doping authority's recommendations. Bone and energy metabolism markers (bone alkaline phosphatase, tartrate-resistant acid phosphatase 5b, total and undercarboxylated osteocalcin, leptin and adiponectin) and related hormones (cortisol and testosterone) were measured, by Sandwich Enzyme Immunoassays, at days -1 (pre-race), 12 and 22 during the race. The power output and the energy expenditure (mean and accumulated) were derived and correlated with the biochemical indexes. During the race, bone metabolism showed that an unbalance in behalf of resorption, which is enhanced, occurred along with a relative increase in the concentration of the undercarboxylated form of osteocalcin that was indirectly related to the enhanced energy expenditure, through adipokines modifications, with leptin decrease (high energy consumption) and adiponectin increase (optimization of energy expenditure). The exertion due to heavy effort induced a decrease of cortisol, while testosterone levels resulted unchanged. In conclusion, during a 3-weeks stage race, bone metabolism is pushed towards resorption. A possible relationship between the bone and the energy metabolisms is suggested by the relative correlations among absolute and relative concentrations trends of undercarboxylated OC, adipokines concentrations, BMI, fat mass (%), power output and the derived energy expenditure.