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Source publication
Horse-racing jockeys are a group of weight-restricted athletes, who have been suggested as undertaking rapid and extreme weight cycling practices in order to comply with stipulated body-mass standards. The aim of this study was to examine bone mass, turnover and endocrine function in jockeys and to compare this group with age, gender and body mass...
Contexts in source publication
Context 1
... indices of bone mass are presented in Table 2. Com- pared to the controls, jockeys had significantly lower BMD, bone mineral concentration and bone area at all measured sites. ...
Context 2
... of anabolic hormonal systems and an associated reduction in bone accrual and mass is likely to be related to the life of chronic weight restriction and energy imbalance previously reported in these athletes [1]. Differences in bone mass were shown to be present between the groups for all absolute variables and the majority of calculated indices (see Table 2). Reduced bone mass is known to increase fracture susceptibility, and this finding may be of particular concern to the horse-racing industry given the high-risk nature of the sport [20]. ...
Context 3
... finding was expected given the allometric relationship which exists between these body composition compart- ments and the theory that lean mass and the associated muscular forces which this measure represents may char- acterize the extent of mechanical loading by which bone is regulated [6,21]. There was, however, a disproportionate relationship between bone and lean mass in the jockey group (see Table 2), a finding which suggests underlying metabolic or systemic influences on bone mass in this group [7]. This theory was confirmed through examination of the hormonal profile of the jockey group. ...
Citations
... Much of the Grand National's attraction can be attributed to the combination of its large and unusual jumps [2] and big field of around 40 competitors. This results in a spectacular test of skill, stamina, and bravery of both human [3][4][5][6] and equine [7,8] athletes, with an element of luck thrown in for good measure. However, what might pass as entertainment for some is cause for concern to others. ...
Simple Summary
The Grand National is one of the world’s most famous steeplechase races. In 2023, the start of the race was delayed, as an animal rights group protested about the race by gaining access to the course. When the race eventually took place, several horses fell, with one sustaining a fatal injury. The ensuing commentary from racing afficionados and animal activists alike laid bare some of the fundamental issues surrounding the sport. This event highlights how the racing industry is increasingly subject to public pressure around the safety and welfare of horses. Public acceptance of activities such as racing is known as “social licence to operate” (SLO) and, as societies and cultures evolve, so too does the concept of social licence; for example, the SLO around circus animals has largely been “lost”, while zoos have managed to maintain their SLO through shifting their focus towards education and the conservation of wild animals. Following the 2023 Grand National, pro- and anti-racing groups shared their views on a variety of media platforms. In this commentary, we consider how the narratives presented might shape the future of the racing industry.
Abstract
The 2023 Grand National steeplechase race was delayed when protesters from the animal rights group, ‘Animal Rising’, gained access to the course just prior to the race. The international media spotlight was focused on what is already a high-profile event and the social licence of both this race and racing in general was scrutinised. Both at the time and for several days afterwards, the general public was exposed to two different narratives from pro- and anti-racing communities. This paper discusses these perspectives and the potential impact on the general public’s relationship with racing. Whilst well-meaning and aiming to promote racing, much of the racing industry’s commentary inadvertently risked damaging its reputation due to a poor understanding of social licence principles. We explore the reasons for these two groups’ alternative perspectives on welfare and suggest considerations for change. Ultimately, if ‘the people’s race’ is to maintain its social licence, the racing community needs to both understand and embrace the concept. Welcoming independent opinions, engaging with different viewpoints, accepting that change is inevitable and, most importantly, being proactive in making changes to prioritise equine welfare will all help racing to move towards greater public acceptance.
... After a 24-hours incubation under standard conditions, the cells were prepared for analysis according to the procedures provided in the individual experiments. The final used SHBG concentration has been selected on the basis of cytotoxicity screening assays and projected from the literature data to reflect the median physiological levels of SHBG in both horses and humans [25,26]. ...
Background
Sex hormone binding globulin (SHBG) deteriorated expression has been recently strongly correlated to increased level of circulating pro-inflammatory cytokines and insulin resistance, which are typical manifestations of equine metabolic syndrome (EMS). Despite previous reports demonstrated the potential therapeutic application of SHBG for liver-related dysfunctions, whether SHBG might modulate equine adipose-derived stem/stromal cells (EqASCs) metabolic machinery remains unknown. Therefore, we evaluated for the first time the impact of SHBG protein on metabolic changes in ASCs isolated from healthy horses.
Methods
Beforehand, SHBG protein expression has been experimentally lowered using a predesigned siRNA in EqASCs to verify its metabolic implications and potential therapeutic value. Then, apoptosis profile, oxidative stress, mitochondrial network dynamics and basal adipogenic potential have been evaluated using various molecular and analytical techniques.
Results
The SHBG knockdown altered the proliferative and metabolic activity of EqASCs, while dampening basal apoptosis via Bax transcript suppression. Furthermore, the cells treated with siRNA were characterized by senescent phenotype, accumulation of reactive oxygen species (ROS), nitric oxide, as well as decreased mitochondrial potential that was shown by mitochondrial membrane depolarization and lower expression of key mitophagy factors: PINK, PARKIN and MFN. The addition of SHBG protein reversed the impaired and senescent phenotype of EMS-like cells that was proven by enhanced proliferative activity, reduced apoptosis resistance, lower ROS accumulation and greater mitochondrial dynamics, which is proposed to be related to a normalization of Bax expression. Crucially, SHBG silencing enhanced the expression of key pro-adipogenic effectors, while decreased the abundance of anti-adipogenic factors namely HIF1-α and FABP4. The addition of exogenous SHBG further depleted the expression of PPARγ and C/EBPα and restored the levels of FABP4 and HIF1-α evoking a strong inhibitory potential toward ASCs adipogenesis.
Conclusion
Herein, we provide for the first time the evidence that SHBG protein in importantly involved in various key metabolic pathways governing EqASCs functions, and more importantly we showed that SHBG negatively affect the basal adipogenic potential of tested ASCs through a FABP4-dependant pathway, and provide thus new insights for the development of potential anti-obesity therapeutic approach in both animals and humans.
Graphical Abstract
... Reported meta-analytic effects have however generally been small and variable. Furthermore, there is evidence that bone may be negatively influenced by high participation in certain sports, e.g., those that emphasize leanness or that have lower-impact and/or repetitive loading cycles [23][24][25][26]. As described by Wherry and colleagues in their recent review [27], exercise provides a complex stimulus to the body, conveying a myriad of signals that may be either catabolic or anabolic to the bone, and the influence of sustained exercise training on bone may ultimately depend on which of these processes dominate. ...
... Reported meta-analytic effects have however generally been small and variable. Furthermore, there is evidence that bone may be negatively influenced by high participation in certain sports, e.g., those that emphasize leanness or that have lower-impact and/or repetitive loading cycles [23][24][25][26]. As described by Wherry and colleagues in their recent review [27], exercise provides a complex stimulus to the body, conveying a myriad of signals that may be either catabolic or anabolic to the bone, and the influence of sustained exercise training on bone may ultimately depend on which of these processes dominate. ...
Background
Circulating biomarkers are often used to investigate the bone response to an acute bout of exercise, but heterogeneity in factors such as study design, quality, selected biomarkers, and exercise and participant characteristics render it difficult to synthesize and evaluate available evidence.
Objective
The aim of this study was to quantify the effects of an acute exercise bout on bone biomarkers, along with the influence of potential moderators such as participant, exercise, and design characteristics, using a systematic review and meta-analytic approach.
Methods
The protocol was designed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) guidelines and prospectively published. Seven databases were systematically searched in accordance with predefined eligibility criteria. Bayesian three-level hierarchical meta-analysis models were used to explore the main effects of acute exercise on bone biomarkers, as well as potential moderating factors. Modelled effect sizes were interpreted according to three metrics, namely (1) evidence of an effect (defined by whether, or how much of, the credible interval [CrI] included zero); (b) the size of that effect (threshold values of 0.01, 0.2, 0.5 and 0.8 were used to describe effect sizes as very small, small, medium and large, respectively); and (c) the level of certainty in the estimated effect (defined using the GRADE framework).
Results
Pooling of outcomes across all designs and categories indicated that an acute bout of exercise increased bone resorption (ES0.5 0.10, 95% CrI 0.00–0.20) and formation (ES0.5 0.05, 95% CrI 0.01–0.08) markers but the effects were very small and highly variable. Furthermore, moderator analyses revealed the source of some of this variability and indicated that exercise type and impact loading influenced the bone resorptive response. A moderate increase in C-terminal telopeptide of type 1 collagen (CTX-1) was observed in response to cycling (ES0.5 0.65, 95% CrI 0.20–0.99), with greater durations and more work leading to larger CTX-1 increases. CTX-1 response peaked within 15 min and 2 h after the exercise bout. Other exercise types did not influence CTX-1. Changes to all bone formation markers were very small and transient, with the very small increases returning to baseline within 15 min of exercise cessation. No major trends for bone formation markers were identified across any of the moderating categories investigated. Certainty of evidence in most outcomes was deemed to be low or very low.
Conclusion
The large influence of an acute bout of prolonged cycling on the bone resorption marker CTX-1, alongside the lack of a response of any biomarker to resistance or high-impact exercise types, indicate that these biomarkers may be more useful at investigating potentially osteolytic aspects of exercise, and raises questions about their suitability to investigate the osteogenic potential of different exercise types, at least in the short term and in response to a single exercise bout. Certainty in all outcomes was low or very low, due to factors including risk of bias, lack of non-exercise controls, inconsistency, imprecision and small-study effects.
Protocol Registration and Publication
This investigation was prospectively registered on the Open Science Framework Registry (https://osf.io/6f8dz) and the full protocol underwent peer review prior to conducting the investigation.
... A substantial body of research exists regarding the bone response to LEA, and this has been reviewed in detail elsewhere [68][69][70]. Briefly, cross-sectional and observational studies of athletes indicate that prolonged exposure to LEA manifests in lower bone mass, compromised bone micro-architecture, perturbed bone metabolism, and lower estimated bone strength [71][72][73][74]. Perturbations in bone biomarkers have also been reported in individuals experimentally exposed to acute periods of LEA (i.e., 3-5 days). ...
The energy costs of athletic training can be substantial, and deficits arising from costs unmet by adequate energy intake, leading to a state of low energy availability, may adversely impact athlete health and performance. Life history theory is a branch of evolutionary theory that recognizes that the way the body uses energy-and responds to low energy availability-is an evolved trait. Energy is a finite resource that must be distributed throughout the body to simultaneously fuel all biological processes. When energy availability is low, insufficient energy may be available to equally support all processes. As energy used for one function cannot be used for others, energetic "trade-offs" will arise. Biological processes offering the greatest immediate survival value will be protected, even if this results in energy being diverted away from others, potentially leading to their downregulation. Athletes with low energy availability provide a useful model for anthropologists investigating the biological trade-offs that occur when energy is scarce, while the broader conceptual framework provided by life history theory may be useful to sport and exercise researchers who investigate the influence of low energy availability on athlete health and performance. The goals of this review are: (1) to describe the core tenets of life history theory; (2) consider trade-offs that might occur in athletes with low energy availability in the context of four broad biological areas: reproduction, somatic maintenance , growth, and immunity; and (3) use this evolutionary perspective to consider potential directions for future research.
... Regardless of origin, LEA can act as a serious impediment to good health and sport performance [28][29][30]. Indeed, there is increasing evidence that exposure to LEA in male athletes is associated with effects on the hypothalamic-pituitary-gonadal (HPG) axis [9,[31][32][33][34][35][36][37][38][39][40][41], changes to immune function [39,42] impairments of bone health [43][44][45] and reproductive function [46], and negative outcomes for performance [42,10] and body composition [47]. ...
A questionnaire-based screening tool for male athletes at risk of low energy availability (LEA) could facilitate both research and clinical practice. The present options rely on proxies for LEA such screening tools for disordered eating, exercise dependence, or those validated in female athlete populations. in which the female-specific sections are excluded. To overcome these limitations and support progress in understanding LEA in males, centres in Australia, Norway, Denmark, and Sweden collaborated to develop a screening tool (LEAM-Q) based on clinical investigations of elite and sub-elite male athletes from multiple countries and ethnicities, and a variety of endurance and weight-sensitive sports. A bank of questions was developed from previously validated questionnaires and expert opinion on various clinical markers of LEA in athletic or eating disorder populations, dizziness, thermoregulation, gastrointestinal symptoms, injury, illness, wellbeing, recovery, sleep and sex drive. The validation process covered reliability, content validity, a multivariate analysis of associations between variable responses and clinical markers, and Receiver Operating Characteristics (ROC) curve analysis of variables, with the inclusion threshold being set at 60% sensitivity. Comparison of the scores of the retained questionnaire variables between subjects classified as cases or controls based on clinical markers of LEA revealed an internal consistency and reliability of 0.71. Scores for sleep and thermoregulation were not associated with any clinical marker and were excluded from any further analysis. Of the remaining variables, dizziness, illness, fatigue, and sex drive had sufficient sensitivity to be retained in the questionnaire, but only low sex drive was able to distinguish between LEA cases and controls and was associated with perturbations in key clinical markers and questionnaire responses. In summary, in this large and international cohort, low sex drive was the most effective self-reported symptom in identifying male athletes requiring further clinical assessment for LEA.
... On the other hand, excess body fat can be perceived as 'dead weight' such that high levels of FM may have a negative impact on performance due to the demands of making weight [7]. Furthermore, low bone mass (preferred term for osteopenia [8]), osteoporosis and the risk of bony injuries are a serious concern for jockeys as previous research has shown a high prevalence of low BMD and impaired bone markers via a multitude of assessment methods [2,[9][10][11][12][13]. ...
... In the current literature on jockey body composition, measurements have been carried out to evaluate BF% using skinfold thickness and skinfold prediction equations and dual-energy X-ray absorptiometry (DXA), while bone status and bone characteristics have been determined using a variety of assessment techniques including DXA, bone turnover markers and peripheral quantitative computed tomography (pQCT). Furthermore, the classification criteria used for interpreting results have been inconsistent across the available literature [2,[9][10][11][12]. Thus, despite over a decade of body composition and bone health assessments in jockeys worldwide, the heterogeneity of the studies conducted makes comparisons, interpretation and prescription between the findings difficult. ...
... In Irish jockeys, LM values were found to be lower in flat (49.4 kg) and NH (53.7 kg) jockeys compared to boxers (58.1 kg) and recreationally active controls (58.0 kg) [26]. The authors suggested the proportionality between bone and LM may help identify the low bone mass [11]. Similar LM values were reported for NH (53.4 kg) jockeys but not flat jockeys (45.7 kg) [32]. ...
Jockeys are unlike other weight-making athletes as the sport of horse racing requires strict weight management to meet the racing stipulations, protracted working hours and an extended racing season with limited downtime. Several studies have reported on the body composition and bone status of male and female professional and retired jockeys, yet the variety of assessment techniques, lack of standardised testing protocols and classification inconsistency make interpretation and comparison between studies problematic. This review aimed to appraise the existing body composition and bone health evidence in jockeys and evaluate the assessment methods and classification criteria used. Dual-energy X-ray absorptiometry (DXA) has been used most frequently in jockey research to assess body composition and bone status, while various generic skinfold equations have been used to predict body fat percentage. Evidence indicates flat jockeys are now taller and heavier than the data reported in earlier studies. Absolute fat mass has steadily increased in male jockeys in the last decade. The bone status of male jockeys remains a concern as constant low bone density (BMD) is evident in a large percentage of young and experienced professional jockeys. Due to limited studies and variations in assessment methods, further research is required to investigate bone turnover markers in male and female jockeys. A standardised testing protocol using internationally recognised assessment guidelines is critical for the accurate interpretation and evaluation of body composition and bone health measurements. Furthermore, establishing jockey-specific BMD and bone turnover reference ranges should be considered using existing and future data.
... 13 Most publications report that jockeys continue to rely on chronic weight cycling and unhealthy practices including severe restrictions on fluid and food intake as well as passive (sauna use) and active (intensive exercise in sweat suits) sweating. 10,26,29,30 One study of 85 Irish jockeys noted that 55.3% of the participants reported difficulty with weight management and 67% reported that they rapidly lost weight at least once a month to race. 8 Practices known to result in dehydration have been consistently reported over the past two decades across jockey populations globally. ...
Numerous publications have described the behaviors employed by professional jockeys on a daily basis to achieve and maintain a minimum racing weight. This narrative review provides an update of recent publications that report on the impact of such practices. Although rapid weight-loss techniques such as calorie restriction and dehydration are commonly thought to be deleterious to jockeys, little evidence exists of enduring health consequences. There is evidence to suggest that jockey training behaviors and dietary choices are not aligned with optimum preparation for the physiological demands of the sport. Further research is necessary to better measure the health impact of jockey weight-making behaviors; such data might guide reforms of athlete behavior and regulatory practices within the global sport of horse racing.
... Between jockey groups, the prevalence of low BMD at the FN (26% vs 7%) and total hip (49% vs 13%) were over three times higher in flat compared to NH jockeys, and double at the LS (59% vs 30%) respectively. Given the awareness from previous research of poor bone density in jockeys and limited signs of improvement, the findings of this study are concerning for the health and welfare of jockeys (7,11,14,26,35,41). Jackson et al., (14) showed a similar trend of reduced bone mass in jockeys from the UK however, the prevalence of low BMD was slightly higher compared to the present study. ...
Compromised bone density in jockeys has previously been identified as an important health and safety concern in horseracing. Despite this, no update on the bone density status in Irish jockeys has been provided in the past decade. The study aimed to conduct a comprehensive update of the current bone density status in professional Irish jockeys and identify possible contributory physical and lifestyle factors. Eighty-five professional male jockeys (flat n = 39; national hunt (NH) n = 46) completed a dual-energy X-ray absorptiometry (DXA) scan for the assessment of body composition and bone mineral density (BMD) at the lumbar spine (LS), femoral neck (FN) and hip, 24-hour food recall, bone-specific physical activity questionnaire (BPAQ) and lifestyle questionnaire on weight making practices and injury history. Z-scores were interpreted to assess current bone density status. Correlation analysis was used to identify physical and lifestyle factors associated with bone mineral apparent density (BMAD). Results revealed a high prevalence of low BMD (Z-score <-1.0) at the LS (44%), FN (15%) and hip (29%) in Irish jockeys. Analysis of jockeys physical characteristics found a positive relationship with the LS but not FN BMAD. Riding experience and timing of weight cut in NH and the practice of cutting weight in flat jockeys negatively influenced BMAD sites, while supplement use in flat jockeys displayed a positive effect on LS BMAD. Findings indicate the need for targeted individualised support strategies. Further investigation is required into jockey-specific intervention strategies that promote the development of optimal bone health in professional jockeys.
... This approach has been reported to be effective in many populations, with metaanalytic data reporting a positive effect of controlled exercise interventions on bone density in a range of populations that include pre- [12] and postmenopausal [13] women, older adults [14], individuals with osteoporosis [15], and children [16]. However, it is important to understand that several of the aforementioned metaanalyses included a number of studies that reported no effect of exercise on the bone, while some studies even suggest that the bone may be negatively impacted by very high volumes or intensities of exercise, e.g., in athletes competing in sports that emphasize leanness or those that rely upon repetitive loading cycles [17][18][19][20]. ...
Background
Bone is a plastic tissue that is responsive to its physical environment. As a result, exercise interventions represent a potential means to influence the bone. However, little is currently known about how various exercise and participant characteristics interact to influence bone metabolism. Acute, controlled, interventions provide an in vivo model through which the acute bone response to exercise can be investigated, typically by monitoring circulating bone biomarkers. Currently, substantial heterogeneity in factors such as study design, quality, exercise, and participant characteristics render it difficult to synthesize and evaluate the available evidence. Using a systematic review and meta-analytic approach, the aim of this investigation is to quantify the effect of an acute exercise bout on circulating bone biomarkers as well as examine the potential factors that may moderate this response, e.g., variation in participant, exercise, and sampling characteristics.
Methods
This protocol was designed in accordance with the PRISMA-P guidelines. Seven databases (MEDLINE, Embase, Sport Discus, Cochrane CENTRAL, PEDro, LILACS, and Ibec) will be systematically searched and supplemented by a secondary screening of the reference lists of all included articles. The PICOS (Population, Intervention, Comparator, Outcomes and Study Design) approach was used to guide the determination of the eligibility criteria. Participants of any age, sex, training, or health status will be considered for inclusion. We will select studies that have measured the bone biomarker response before and after an acute exercise session. All biomarkers considered to represent the bone metabolism will be considered for inclusion, and sensitivity analyses will be conducted using reference biomarkers for the measurement of bone resorption and formation (namely β-CTX-1 and P1NP). Multi-level, meta-regression models within a Bayesian framework will be used to explore the main effect of acute exercise on bone biomarkers as well as potential moderating factors. The risk of bias for each individual study will be evaluated using a modified version of the Downs and Black checklist while certainty in resultant outcomes will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.
Discussion
A better understanding of the bone metabolic response to an acute bout of exercise has the potential to advance our understanding of the mechanisms through which this stimulus impacts bone metabolism, including factors that may moderate this response. Additionally, we will identify current gaps in the evidence base and provide recommendations to inform future research.
Systematic review registration
This protocol was prospectively registered in the Open Science Framework Registry (https://osf.io/6f8dz)
