INTRODUCTION Professional jockeys are considered elite sportsmen competing in a sport with certain weight restrictions. Horse racing is categorized as a “weight-making” sport where jockeys can benefit from attaining and/or maintaining a specific weight for competition. The minimum riding weight for professional jockeys and apprentice jockeys who are race riding is currently 52 kg. The lighter the jockey (i.e. the closer he can remain to the minimum weight of 52 kg) the more rides may be allocated to him (and the more money he will earn). This places a great deal of pressure on the jockey to maintain a low body weight, in order to attain rides. Unlike other weight category sports, horse riding does not have an “off season”, therefore jockeys are constantly pressured to maintain a minimal weight. Consequently this may result in unhealthy eating habits, dangerous weight control practices and compromised health. Research on the weight making practices of apprentice jockeys is scarce. In fact, there is currently no published data available on the South African apprentice jockey. The aim of this study was therefore to examine the dietary intake, energy availability and weight control practices of male apprentice jockeys residing at the South African Jockey Academy. METHODS Twenty one male flat jockey apprentices of different race groups, between the ages of 16 and 20 years were recruited to take part in this cross sectional observational study. Height, weight and body composition (body fat percentage and fat free mass) were measured. The apprentices completed a 59-item nutrition, health and lifestyle questionnaire including questions on weight control and weight making practices. Dietary intake was recorded with a 24-hour dietary recall on four non-consecutive days including a rest day, two training days, and a race day. On these days, exercise energy expenditure was also recorded with Actiheart© monitors with the aim to calculate energy availability. MAIN FINDINGS Total mean reported energy intake of the participants was 7088±2337kJ (35.5±12.5kcal/kg fat free mass [FFM]) and below the recommendations for athletes exercising several hours per day for most days of the week. The micronutrient intakes of the majority of these jockeys were also low (i.e. <67% of recommended intake). Mean calculated energy availability (EA) over two training days and one rest day was 27.1±16.7 kcal/kg FFM and regarded as low (i.e.<30kcal/kg/FFM). Furthermore, the majority of apprentices (88%) had a low EA on the training days. Ninety one percent of the jockeys reported the use of one or more weight control method including food avoidance (81%), restricting food intake and skipping meals (67%), exercising to sweat (48%) and using the sauna (43%). The top three reported side effects from making weight included thirst (80%), hunger (75%) and tiredness (75%). CONCLUSION In conclusion, the results of the present study showed that the majority of South African apprentice jockeys are practicing weight control methods, specifically restricting energy and food intake, to control their weight. This was supported by the mean low dietary energy intake and sub-optimal mean energy availability. These apprentice jockeys are therefore at risk for long-term health consequences including low bone mineral density. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

INTRODUCTION Professional jockeys are considered elite sportsmen competing in a sport with certain weight restrictions. Horse racing is categorized as a “weight-making” sport where jockeys can benefit from attaining and/or maintaining a specific weight for competition. The minimum riding weight for professional jockeys and apprentice jockeys who are race riding is currently 52 kg. The lighter the jockey (i.e. the closer he can remain to the minimum weight of 52 kg) the more rides may be allocated to him (and the more money he will earn). This places a great deal of pressure on the jockey to maintain a low body weight, in order to attain rides. Unlike other weight category sports, horse riding does not have an “off season”, therefore jockeys are constantly pressured to maintain a minimal weight. Consequently this may result in unhealthy eating habits, dangerous weight control practices and compromised health. Research on the weight making practices of apprentice jockeys is scarce. In fact, there is currently no published data available on the South African apprentice jockey. The aim of this study was therefore to examine the dietary intake, energy availability and weight control practices of male apprentice jockeys residing at the South African Jockey Academy. METHODS Twenty one male flat jockey apprentices of different race groups, between the ages of 16 and 20 years were recruited to take part in this cross sectional observational study. Height, weight and body composition (body fat percentage and fat free mass) were measured. The apprentices completed a 59-item nutrition, health and lifestyle questionnaire including questions on weight control and weight making practices. Dietary intake was recorded with a 24-hour dietary recall on four non-consecutive days including a rest day, two training days, and a race day. On these days, exercise energy expenditure was also recorded with Actiheart© monitors with the aim to calculate energy availability. MAIN FINDINGS Total mean reported energy intake of the participants was 7088±2337kJ (35.5±12.5kcal/kg fat free mass [FFM]) and below the recommendations for athletes exercising several hours per day for most days of the week. The micronutrient intakes of the majority of these jockeys were also low (i.e. <67% of recommended intake). Mean calculated energy availability (EA) over two training days and one rest day was 27.1±16.7 kcal/kg FFM and regarded as low (i.e.<30kcal/kg/FFM). Furthermore, the majority of apprentices (88%) had a low EA on the training days. Ninety one percent of the jockeys reported the use of one or more weight control method including food avoidance (81%), restricting food intake and skipping meals (67%), exercising to sweat (48%) and using the sauna (43%). The top three reported side effects from making weight included thirst (80%), hunger (75%) and tiredness (75%). CONCLUSION In conclusion, the results of the present study showed that the majority of South African apprentice jockeys are practicing weight control methods, specifically restricting energy and food intake, to control their weight. This was supported by the mean low dietary energy intake and sub-optimal mean energy availability. These apprentice jockeys are therefore at risk for long-term health consequences including low bone mineral density. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

No description available.

Thesis (M.A. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

Thesis (M.A. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

Thesis (M.A. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

No description available.

Low energy availability (LEA) has been identified as the underlying etiology of the Female Athlete Triad and Relative Energy Deficiency in Sport (REDs) syndrome. The term energy availability (EA) describes the amount of dietary energy intake (EI) that is remaining to support physiological function after accounting for the energy cost of exercise. Exposure to LEA stimulates metabolic adaptations that may disrupt certain biological systems, such as endocrine function, and impair sports performance. Controlled laboratory research has shown suppression of bone formation biomarkers with accelerated rates of bone resorption after only three to five days of LEA in active females. Correcting LEA by increasing EI or decreasing exercise energy expenditure (EEE) may not be feasible for all athletes and additional approaches for protecting bone health during LEA require further investigation. Recent evidence suggests that brief bouts of high-impact exercise attenuate the increased rate of bone resorption in females with diet-induced LEA. However, it is unknown whether similar exercises have a protective effect on bone health when LEA is induced through a combination of dietary restriction and exercise. A gap also remains in the understanding of how EA fluctuates throughout the athletic season and what potential effect that has on body composition and performance outcomes. To address these gaps, we conducted two studies to investigate the interactions of EA, bone health, and body composition. The first investigation employed a randomized crossover design in which female runners underwent two, five-day experimental conditions of LEA consisting of dietary restriction and daily running (EA = 15 kcal·kg FFM-1·day-1). During one of the experimental conditions, participants also completed a bout of 50 jumping exercises daily. Serum markers of bone resorption (C-terminal cross-linking telopeptide of type 1 collagen [CTX-I]), bone formation (N-terminal propeptide of type 1 procollagen [PINP]), and hormonal profiles were compared between baseline and post-intervention using linear mixed effects modeling. We hypothesized that daily high-impact exercise would have a positive effect on bone by attenuating the rise in bone resorption. In contrast to our hypothesis, bone resorption marker CTX-I increased following both LEA conditions (+12%, P=0.004) with no difference in the response between the jumping and non-jumping conditions. Bone formation was not suppressed following either LEA condition. Concentrations of free triiodothyronine (T3), insulin-like growth factor-1, leptin, and insulin decreased in response to five days of LEA independent of condition (P<0.05); however, when taking into account condition, the decrease in free T3 was only statistically significant following the LEA condition without jumping (-27%, P=0.022, Cohen's d=0.87). Our findings suggest that high-impact jumping exercises are not an effective countermeasure to protect bone health during short-term LEA in female runners who continue to run routinely. In a second study, we conducted a longitudinal, observational study in collegiate male soccer players to investigate seasonal changes in EA and body composition. Measurements of EA, body composition, and sports performance were assessed at the start and end of the non-championship Spring athletic season. We hypothesized that EA would be positively associated with changes in body composition at the end of the three-month season. Despite most athletes reporting desires to gain total and/or lean body mass, no changes in EA or body composition were detected at the end of the season compared to the start. Furthermore, sports performance and bone density improved across the season regardless of individual changes in EA. These results indicate EA of collegiate male soccer players during the Spring season is sufficient to maintain current body composition and improve sports performance, but insufficient to support total and/or lean body mass gains. / Doctor of Philosophy / Adequate energy intake (EI) is essential for fueling athletic performance and supporting general health. Low energy availability (LEA) occurs when EI is insufficient to meet the energy demands of both exercise and basic health functions. Athletes with LEA may experience various repercussions such as suppressed metabolism, hormonal changes, and impaired bone health. Training adaptations may also be impaired by LEA, thereby affecting athletic performance. Daily high-impact jumping exercises have been shown to have a positive effect on bone health in women, even during periods of LEA caused by dietary restriction. However, this type of exercise intervention has not been tested in combination with other forms of daily exercise in women exposed to a controlled period of LEA. The purpose of these studies was to examine how exercise and EA affect bone health and body composition in recreational and competitive athletes. The first study investigated the effects of daily jumping exercises on markers of bone formation and breakdown during five days of LEA in female runners. The completion of 50 jumping exercises each day along with running on a treadmill was not shown to provide additional bone-protective benefits during LEA compared to running alone, as shown by similar rates of bone breakdown observed under both conditions. The second study investigated whether changes occur in EA or body composition in male collegiate soccer players over an athletic season. Despite most of the athletes reporting desires to gain weight or muscle during the season, there were no differences in body composition or EA at the end of the season compared to the start. However, there were significant improvements in aerobic fitness, relative strength, and bone density throughout the season.

Background: Achilles tendinopathy is a common and debilitating condition among female ballet dancers due to the large repetitive loading forces placed on their Achilles tendons during rehearsals and performances. Tendon health problems in females are exacerbated by a lack of understanding about how energy availability influences tendons. Ballet dancers, as aesthetic athletes, are vulnerable to low energy availability and can enter a spectrum disorder, relative energy deficiency in sport, that consists of low energy availability (with or without disordered eating), menstrual cycle dysfunction, and low bone mineral density (BMD). Aims: 1) To investigate the relationship between insufficient caloric intake and Achilles tendon health in pre-professional ballet dancers. 2) To evaluate if symptoms of relative energy deficiency in sport such as low BMD and menstrual irregularity can be matched with Achilles tendon structural damage in pre-professional ballet dancers. 3) To analyze if there is a relationship between BMD and nutrition in pre-professional ballet dancers. Methods: 30 pre-professional ballet dancers were recruited. Over the course of a 16-week training and performance period, the dancers underwent four ultrasound imaging sessions and two MRI sessions investigating their Achilles tendons. They also underwent one full body DXA scan and completed four ASA24 dietary recall surveys. The dancers additionally filled out questionnaires describing their menstrual history and current Achilles tendon health. At the end of the study, dancers were organized into calorie sufficiency groups (sufficient or insufficient). Results: Within both calorie groups, the Achilles tendon was significantly thicker at the end of the study as compared to the start of the study (p=.046). Within both calorie groups, echogenicity was significantly higher at the first two ultrasound imaging sessions than it was at the last two (p<.05). Additionally, the calorie sufficient group's tendons had a significantly higher echogenicity than the calorie insufficient group at the first two ultrasound imaging sessions (p<.05). There were significantly more dancers in the calorie insufficient group that experienced changes to their menstrual cycle (p=.007). Conclusion: Participants in the calorie sufficient group had significantly more hyperechoic tendons than those in the calorie insufficient group at the start of the study, and all participants saw a significant drop in tendon echogenicity halfway through the study. The results of this study suggest that a better understanding of how average caloric intake affects tendon health in dancers is necessary in order to help treat and prevent AT injuries in this dance population.

No description available.