Nutrition factors associated with rib stress injury in elite rowers

Rib stress injuries (RSI) contribute the highest loss of training time of all rowing related injuries, negatively affecting training consistency and the ability to produce optimal performances when needed. Nutrition interacts with training to moderate bone growth, repair and maintenance and, as such, is of interest in understanding changeable contributors to injury. Given the scarcity of available research, this thesis investigated nutrition factors associated with RSI, the development of a tool to assess one of these factors, low energy availability (LEA), and the effects of acute calcium intake on markers of bone turnover (BTM) over a typical training day. Study 1 (Chapter 4) was a cross-sectional analysis of RSI history and related nutrition factors in elite Australian rowers (n= 133). Bone mineral density (BMD), body composition, vitamin D and K status, usual calcium intake, menstrual history, diet restriction, age, sex, training age and injury history were assessed. Diet restriction was inversely related to spine and rib BMD. Vitamin D and K status, and calcium intake were not associated with injury. Among rowers with RSI history, lightweight males had lower total bone mass, femur and rib BMD, whereas heavyweight females had lower rib BMD. In relation to RSI history, the best models included rib, spine or femur BMD with age, body fat and sex. A female specific model included current menstrual dysfunction, age and body fat levels. Study 2 (Chapter 6) aimed to develop and validate a screening tool for low energy availability (LEA) in male athletes. This was a multi-centre collaboration, recruiting male athletes (n=310) from a variety of sports. Multivariate analysis was used to identify associations between variable responses and clinical markers, and Receiver Operating Characteristics (ROC) curve analysis of variables, with an inclusion threshold of 60% sensitivity. Of the 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. 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. Study 3 (Chapter 8) examined the influence of acute calcium intake on bone turnover markers over a typical training day in elite male rowers. While acute exercise typically increases BTM, the impact of subsequent sessions and the interaction with pre-exercise calcium intake remains unclear despite the application to the ‘real life’ training of athletes. Using a randomized crossover design, elite male rowers (n=16) completed two trials, a week apart, consisting of two 90-minute rowing ergometer sessions (Ex1, Ex2) separated by 150min. Prior to each trial, participants consumed a high (CAL: ~1000 mg) or isocaloric low (CON: <10 mg) calcium meal. BTM (parathyroid hormone: PTH; C-terminal telopeptide of type I collagen: β-CTX-I; osteocalcin: OC) and serum ionised calcium (iCa) were monitored from baseline to 3 hours post Ex2. While each session caused perturbances of serum iCa, CAL maintained calcium concentrations above those of CON for most time points, 4.5 and 2.4% higher post EX1 and EX2 respectively. The decrease in iCa in CON was associated with an elevation of blood PTH and β-CTX-I over this period of repeated training sessions and their recovery, particularly during and after Ex2. Pre-exercise intake of a calcium-rich meal prior to training sessions undertaken within the same day had a cumulative and prolonged effect on the stabilisation of blood iCa during exercise. In turn, this reduced the post-exercise PTH response, potentially attenuating the increase in markers of bone resorption. Collectively the findings of the thesis were 1. Clarification of associations between nutrition factors and RSI history informing future monitoring and interventions, LEA is important. 2. Association of rib BMD with RSI providing practical benefits to frequency of monitoring and lower radiation dose, opening avenues for better characterisation of its relationship with RSI. 3. Sex drive is an important indicator of LEA in male athletic populations 4. Pre-exercise calcium has the potential to safeguard long term bone health and reduce the risk of bone stress injuries and is a practical strategy, easily integrated into the athlete’s overall sports nutrition plan, complementing those adequacy of EA

Screening for Low Energy Availability in Male Athletes: Attempted Validation of LEAM-Q

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Screening for low energy availability in male athletes : Attempted validation of LEAM-Q

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

The impact of acute calcium intake on bone turnover markers during a training day in elite male rowers

Introduction: While an acute exercise session typically increases bone turnover markers (BTM), the impact of subsequent sessions and the interaction with pre-exercise calcium intake remains unclear despite the application to the ‘real life’ training of many competitive athletes. Methods: Using a randomized crossover design, elite male rowers (n = 16) completed two trials, a week apart, consisting of two 90-minute rowing ergometer sessions (Ex1, Ex2) separated by 150 minutes. Prior to each trial, participants consumed a high (CAL: ~1000 mg) or isocaloric low (CON: \u3c 10 mg) calcium meal. Biochemical markers including parathyroid hormone: PTH; serum ionised calcium (iCa) and bone turnover markers (C-terminal telopeptide of type I collagen: β-CTX-I; osteocalcin: OC) were monitored from baseline to 3 hours post Ex2. Results: While each session caused perturbances of serum iCa, CAL maintained calcium concentrations above those of CON for most time points, 4.5 and 2.4 % higher post EX1 and EX2 respectively. The decrease in iCa in CON was associated with an elevation of blood PTH (p \u3c 0.05) and β-CTX-I (p \u3c 0.0001) over this period of repeated training sessions and their recovery, particularly during and after Ex2. Pre-exercise intake of calcium-rich foods lowered BTM over the course of a day with several training sessions. Conclusions: Pre-exercise intake of a calcium-rich meal prior to training sessions undertaken within the same day had a cumulative and prolonged effect on the stabilisation of blood iCa during exercise. In turn, this reduced the post-exercise PTH response, potentially attenuating the increase in markers of bone resorption. Such practical strategies may be integrated into the athlete’s overall sports nutrition plan, with the potential to safeguard long term bone health and reduce the risk of bone stress injuries

Inflammation and Oral Contraceptive Use in Female Athletes Before the Rio Olympic Games

This study investigated the association between synthetic ovarian hormone use [i.e., the oral contraceptive (OC) pill] and basal C-reactive protein (CRP), peripheral blood immune cell subsets, and circulating pro- and anti-inflammatory cytokine concentrations in elite female athletes. Elite female athletes (n = 53) selected in Rio Summer Olympic squads participated in this study; 25 were taking an OC (AthletesOC) and 28 were naturally hormonally cycling (AthletesNC). Venous blood samples were collected at rest for the determination of sex hormones, cortisol, CRP, peripheral blood mononuclear memory and naïve CD4+ T-cells, CD8+ T-cells and natural killer cells, as well as pro- and anti-inflammatory cytokine concentrations. C-reactive protein concentrations were elevated (p < 0.001) in AthletesOC (median = 2.02, IQR = 3.15) compared to AthletesNC (median = 0.57, IQR = 1.07). No differences were reported for cortisol, cytokines, or PBMC immune cell subsets, although there was a trend (p = 0.062) for higher IL-6 concentrations in AthletesNC. Female Olympians had substantially higher CRP concentrations, a marker of inflammation and tissue damage, before the Rio Olympic Games if they used an OC. Future research should examine the potential consequences for athlete performance/recovery so that, if necessary, practitioners can implement prevention programs

Nutrition factors associated with rib stress injury history in elite rowers

Objectives To investigate associations between nutrition factors (diet restriction, menstrual status, calcium intake, vitamin D and K status), bone mineral density (BMD) and rib stress injury (RSI) history. Design Cross-sectional. Methods 133 elite rowers completed a self-report questionnaire to collect information regarding training and injury history, menstrual status and diet restriction, and a calcium intake questionnaire (SCQ2002). BMD and body composition were assessed by dual-energy X-ray absorptiometry. A sub-group (n = 68) had vitamin D and K status assessed from fasted morning blood. History of RSI was self-reported and verified against medical records. Characteristics of injured and uninjured rowers were compared (one-way ANOVA), while relationships with BMD (multiple linear regression) and RSI (multiple logistic regression) were modelled. Results Diet restriction was inversely related to spine BMD and rib BMD. Within sex, vitamin D and K status, and calcium intake were not associated with injury. Among rowers with RSI history, lightweight males had lower total bone mass, femur BMD and rib BMD, whereas heavyweight females had lower rib BMD. In relation to RSI history, the best models included rib, spine or femur BMD with age, body fat and sex. A female-specific model included rib BMD, current menstrual dysfunction, age and body fat levels. Conclusions BMD, including that of the rib, diet restriction, menstrual function and weight category were associated with rib injury history and should be considered in the management of elite rowers

Pitfalls of conducting and interpreting estimates of energy availability in free-living athletes

The human body requires energy for numerous functions including, growth, thermogenesis, reproduction, cellular maintenance, and movement. In sports nutrition, energy availability (EA) is defined as the energy available to support these basic physiological functions and good health once the energy cost of exercise is deducted from energy intake (EI), relative to an athlete’s fat-free mass (FFM). Low EA provides a unifying theory to link numerous disorders seen in both female and male athletes, described by the syndrome Relative Energy Deficiency in Sport, and related to restricted energy intake, excessive exercise or a combination of both. These outcomes are incurred in different dose–response patterns relative to the reduction in EA below a “healthy” level of ∼45 kcal·kg FFM−1·day−1. Although EA estimates are being used to guide and monitor athletic practices, as well as support a diagnosis of Relative Energy Deficiency in Sport, problems associated with the measurement and interpretation of EA in the field should be explored. These include the lack of a universal protocol for the calculation of EA, the resources needed to achieve estimates of each of the components of the equation, and the residual errors in these estimates. The lack of a clear definition of the value for EA that is considered “low” reflects problems around its measurement, as well as differences between individuals and individual components of “normal”/“healthy” function. Finally, further investigation of nutrition and exercise behavior including within- and between-day energy spread and dietary characteristics is warranted since it may directly contribute to low EA or its secondary problems

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