Diet, body composition, and bone mass in well-trained cyclists

Professional cyclists have lower levels of bone markers than amateurs. Is there a risk of osteoporosis in cyclist?

Currently, there is a greater number of amateurs that practice cycling. However, there is no clear evidence regarding bone health in amateur cyclists compared to professional cyclists, as the latter has shown to have lower bone mineral content and density. Therefore, the aim of this study was to identify the differences in bone variables between professional (PRO) and amateur (AMA) road cyclists, and to see if these differences were related to differences in cycling performance. A parallel trial was carried out with 15 AMA and 10 PRO cyclists. All cyclists visited the laboratory twice: 1) in a fasted state, body composition measured by dual-energy X-ray absorptiometry (DXA) and 2) physiological variables measured using an incremental test until exhaustion. Significantly lower values were found in bone mineral density, bone mineral content and fat free mass in PRO compared to AMA (p < 0.05). In addition, significantly higher power was produced in ventilatory thresholds 1 and 2 (VT1 and VT2) and VO_2MAX in PRO compared to AMA (p < 0.05). Overall, PRO cyclists had lower values in bone health and muscle mass but better results in performance compared to AMA.

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.

Study on physical fitness factors affecting race-class of Korea racing cyclists

The purpose of this study is to compare and analyze the difference of isokinetic muscle functions, anaerobic capabilities, pedaling power and maximum strength according to race-class of Korea racing cyclists. The participants in this study were 57 racing cyclist candidates who graduated from the Korea racing school. One year after graduation, we confirmed race-class of candidates and they were divided into three groups: the first-class racer group (FC, n=14), second-class racer group (SC, n=29), third-class racer group (TC, n=14). The isokinetic muscle strength of trunk and knee flexion/extension was measured using HUMAC NORM and basic physical strength such as squat and bench press was analyzed by Ariel device. As results of this study, % Fat (percentage of body fat) in FC group was the lowest compared to other groups. Isokinetic knee flexion strength was higher in FC group than SC and TC racer groups. Peak and average pedaling power as well as maximum muscle strength were significantly higher in FC group than in other groups. Our findings suggest new evidence that pedaling power and isokinetic muscle strength might be closely associated with race-class of Korea racing cyclists.

The Role of Energy Availability in Reproductive Function in the Female Athlete Triad and Extension of its Effects to Men: An Initial Working Model of a Similar Syndrome in Male Athletes

The Female Athlete Triad represents three interrelated conditions of (i) low energy availability (energy deficiency), presenting with or without disordered eating, (ii) menstrual dysfunction, and (iii) poor bone health, each of which can exist along a continuum of severity ranging from mild and moderate subclinical health concerns to severe clinical outcomes, including eating disorders, amenorrhea, and osteoporosis. This review provides a brief overview of the Female Athlete Triad, including updating the current thinking regarding energy availability and how it relates to reproductive function, and sets the stage for an initial working model of a similar syndrome in males that will be based on currently available evidence and will later be defined and referred to as a Male Athlete Triad by the newly re-named Female and Male Athlete Triad Coalition. A primary focus of this paper will be on the physiology of each Triad model with an emphasis on low energy availability and its role in reproductive function, with a brief introduction on its effects on bone health in men. From the data reviewed, (i) a specific threshold of energy availability below which menstrual disturbances are induced is not supported; (ii) it appears that the energetic, reproductive, and bone systems in men are more resilient to the effects of low energy availability compared to those of women, requiring more severe energetic perturbations before alterations are observed; and (iii) it appears that recovery of the hypothalamic pituitary gonadal axis can be observed more quickly in men than in women.

Total Energy Expenditure, Energy Intake, and Body Composition in Endurance Athletes Across the Training Season: A Systematic Review

BACKGROUND

Endurance athletes perform periodized training in order to prepare for main competitions and maximize performance. However, the coupling between alterations of total energy expenditure (TEE), energy intake, and body composition during different seasonal training phases is unclear. So far, no systematic review has assessed fluctuations in TEE, energy intake, and/or body composition in endurance athletes across the training season. The purpose of this study was to (1) systematically analyze TEE, energy intake, and body composition in highly trained athletes of various endurance disciplines and of both sexes and (2) analyze fluctuations in these parameters across the training season.

METHODS

An electronic database search was conducted on the SPORTDiscus and MEDLINE (January 1990-31 January 2015) databases using a combination of relevant keywords. Two independent reviewers identified potentially relevant studies. Where a consensus was not reached, a third reviewer was consulted. Original research articles that examined TEE, energy intake, and/or body composition in 18-40-year-old endurance athletes and reported the seasonal training phases of data assessment were included in the review. Articles were excluded if body composition was assessed by skinfold measurements, TEE was assessed by questionnaires, or data could not be split between the sexes. Two reviewers assessed the quality of studies independently. Data on subject characteristics, TEE, energy intake, and/or body composition were extracted from the included studies. Subjects were categorized according to their sex and endurance discipline and each study allocated a weight within categories based on the number of subjects assessed. Extracted data were used to calculate weighted means and standard deviations for parameters of TEE, energy intake, and/or body composition.

RESULTS

From 3589 citations, 321 articles were identified as potentially relevant, with 82 meeting all of the inclusion criteria. TEE of endurance athletes was significantly higher during the competition phase than during the preparation phase (p < 0.001) and significantly higher than energy intake in both phases (p < 0.001). During the competition phase, both body mass and fat-free mass were significantly higher compared to other seasonal training phases (p < 0.05).

CONCLUSIONS

Limitations of the present study included insufficient data being available for all seasonal training phases and thus low explanatory power of single parameters. Additionally, the classification of the different seasonal training phases has to be discussed. Male and female endurance athletes show important training seasonal fluctuations in TEE, energy intake, and body composition. Therefore, dietary intake recommendations should take into consideration other factors including the actual training load, TEE, and body composition goals of the athlete.

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.

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.

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.

Low fatness, reduced fat intake and adequate plasmatic concentrations of LDL-cholesterol are associated with high bone mineral density in women: a cross-sectional study with control group

BACKGROUND

Several parameters are associated with high bone mineral density (BMD), such as overweight, black background, intense physical activity (PA), greater calcium intake and some medications. The objectives are to evaluate the prevalence and the main aspects associated with high BMD in healthy women.

METHODS

After reviewing the database of approximately 21,500 BMD scans performed in the metropolitan area of São Paulo, Brazil, from June 2005 to October 2010, high BMD (over 1400 g/cm² at lumbar spine and/or above 1200 g/cm² at femoral neck) was found in 421 exams. Exclusion criteria were age below 30 or above 60 years, black ethnicity, pregnant or obese women, disease and/or medications known to interfere with bone metabolism. A total of 40 women with high BMD were included and matched with 40 healthy women with normal BMD, paired to weight, age, skin color and menopausal status. Medical history, food intake and PA were assessed through validated questionnaires. Body composition was evaluated through a GE-Lunar DPX MD + bone densitometer. Radiography of the thoracic and lumbar spine was carried out to exclude degenerative alterations or fractures. Biochemical parameters included both lipid and hormonal profiles, along with mineral and bone metabolism. Statistical analysis included parametric and nonparametric tests and linear regression models. P < 0.05 was considered significant.

RESULTS

The mean age was 50.9 (8.3) years. There was no significant difference between groups in relation to PA, smoking, intake of calcium and vitamin D, as well as laboratory tests, except serum C-telopeptide of type I collagen (s-CTX), which was lower in the high BMD group (p = 0.04). In the final model of multivariate regression, a lower fat intake and body fatness as well a better profile of LDL-cholesterol predicted almost 35% of high BMD in women. (adjusted R2 = 0.347; p < 0.001). In addition, greater amounts of lean mass and higher IGF-1 serum concentrations played a protective role, regardless age and weight.

CONCLUSION

Our results demonstrate the potential deleterious effect of lipid metabolism-related components, including fat intake and body fatness and worse lipid profile, on bone mass and metabolism in healthy women.

Bone mineral density results influencing health-related behaviors in male athletes at risk for osteoporosis

The purposes of this study were to determine the role of bone mineral density (BMD) and mood in influencing health-related behaviors of serious leisure male athletes (cyclists and triathletes) at risk for osteoporosis. A cross-sectional design evaluated BMD in 18-60-yr-old serious leisure male cyclists by dual-energy X-ray adsorptiometry (DXA). Activity was measured using the International Physical Activity Questionnaire; personality was assessed using the NEO-60; and quality of life using Short-Form Health 12 (SF-12). Participants completed an online survey questionnaire after completing their DXA testing a minimum of 3 mo before assessing health-related behaviors and general attitudes toward general health and well-being. Forty-two (61.9%) participants responded to the follow-up questionnaire. Serious leisure male athletes are more likely to initiate significant health-related behavioral changes after learning of their bone density results including calcium supplementation and weight-bearing exercise. Men with low BMD (LBMD) had higher openness subscales on NEO-60 compared with men with normal BMD. SF-12 mental and physical health scores were significantly lower in men with LBMD. Perhaps, the interaction and interplay of genetics, activity and behaviors, and aspects of mental and psychological functions contribute to their reduction in BMD and heightened risk for fracture. Findings from this study suggest that early BMD testing in "serious athletes" has important clinical relevance for their potential risk for osteoporosis in the future.