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

Published Article / Direct feeding damage to head lettuce (Lactuca sativa L.) by varying aphid populations in two differently constructed shadehouse structures (fully- and partially covered) was examined. Fresh lettuce head weight, the number of lettuce leaves formed, and the number of lettuce leaves infested with aphids were compared between the two structures. Warmer months showed a significant lower fresh lettuce head weight in the fully covered structure with more aphid-infested leaves. During June/September, the mean number of aphid-infested leaves and aphid infestation levels were significantly higher in the partially covered structure. Visible feeding damage to the lettuce crop was restricted, but asymptomatic damage in terms of a decrease in head weight did occur under severe infestation levels.

BACKGROUND:Obesity is an urgent public health problem, yet only a few clinical trials have systematically tested the efficacy of long-term weight-loss maintenance interventions. This randomized clinical trial tested the efficacy of a novel mind and body technique for weight-loss maintenance.METHODS:Participants were obese adults who had completed a six-month behavioral weight-loss program prior to randomization. Those who successfully lost weight were randomized into either an experimental weight-loss maintenance intervention, Tapas Acupressure Technique (TAT(R)), or a control intervention comprised of social-support group meetings (SS) led by professional facilitators. TAT combines self-applied light pressure to specific acupressure points accompanied by a prescribed sequence of mental steps. Participants in both maintenance conditions attended eight group sessions over six months of active weight loss maintenance intervention, followed by an additional 6 months of no intervention. The main outcome measure was change in weight from the beginning of the weight loss maintenance intervention to 12 months later. Secondary outcomes were change in depression, stress, insomnia, and quality of life. We used analysis of covariance as the primary analysis method. Missing values were replaced using multiple imputation.RESULTS:Among 285 randomized participants, 79% were female, mean age was 56 (standard deviation (sd) = 11), mean BMI at randomization was 34 (sd = 5), and mean initial weight loss was 9.8 kg (sd = 5). In the primary outcome model, there was no significant difference in weight regain between the two arms (1.72 kg (se 0.85) weight regain for TAT and 2.96 kg (se 0.96) weight regain for SS, p < 0.097) Tests of between- arm differences for secondary outcomes were also not significant. A secondary analysis showed a significant interaction between treatment and initial weight loss (p < .036), with exploratory post hoc tests showing that greater initial weight loss was associated with more weight regain for SS but less weight regain for TAT.CONCLUSIONS:The primary analysis showed no significant difference in weight regain between TAT and SS, while secondary and post hoc analyses indicate direction for future research.TRIAL REGISTRATION:ClinicalTrials.gov: NCT00526565

The automotive industry is facing a great challenge - reducing the weight of their vehicles. Carbon fibre composites are regarded by many as the only real option as traditional engineering materials are now running out of potential for further weight reduction. In this doctoral thesis a framework is presented which will provide guidelines for the conceptual phase of the development of an automotive composite body structure. The framework is initiated by defining ideal material diversity, as well as initial partition of the body structure based on process and material selection. Then, a further analysis of the structures is made in order to evaluate whether a more cost efficient solution can be found by further dividing the structure. Such a differential design approach is analysed in the third part of the work, studying both the financial and structural effects of such partitioning. In order to increase the understanding of the intimate relationship between design, material and manufacturing process, balancing manufacturing and structural optimization is addressed. Finally, drape simulation tools are used to assess the geometric complexity of composite structures in order to further quantify suitable split lines in cases of differential design approach. Different carbon fibre composite material systems and processes are compared and evaluated in the work. The results show that a high-performance material system with continuous fibres is both more cost and performance effective as compared to industrialised, discontinuous fibre composites. Further analysis shows the importance of balancing the design for manufacturing and the structural weight optimization of the structures in order to reach a cost and weight effective design. When restricting composite design freedom with manufacturing constraints, the great benefits of structural composites disappear and with this both weight and cost effectiveness. / <p>QC 20160418</p>

No description available.

The preschool years are an important time in the development of understanding the property of weight. This experiment investigates whether social learning, specifically imitation, will promote preschoolers’ use of this property. Children were randomly assigned to one of three groups. Those in the experimental group saw an adult sort four objects based on their weights. Children were then presented with the objects. Whether children sorted these objects based on their weights was scored, as was their sorting of a novel set of objects (to assess generalization) and their imitation of the hefting gestures used by the adult. Comparisons to control groups indicated that 4-year-olds, but not 3-year-olds, benefitted from the modeling and sorted by weight. These results suggest that social learning is an effective way to promote children’s use of this invisible property.

No description available.

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

published_or_final_version / Anatomy / Master / Master of Science