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- Volume 26, Issue 2, 2014
South African Journal of Sports Medicine - Volume 26, Issue 2, 2014
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Volume 26, Issue 2, 2014
Author Mike LambertSource: South African Journal of Sports Medicine 26 (2014)More Less
I did a double take when I received an email from a friend with the subject line 'How to run "naked" - and love it'. My immediate thought was that he had lost his marbles, but I clicked on the link not quite sure what to expect. My concern was ill-founded because the link directed me to a blog about the joys of running free of smartphones, heartrate monitors, headphones, GPS devices, etc.; 'naked' was referring to the deprivation of technology. The article implied that technology, which has become such an important part of running, detracted from the natural joys of running - the very thing that was attractive in the beginning.
Body composition and habitual and match-day dietary intake of the FNB Maties Varsity Cup rugby players : original researchSource: South African Journal of Sports Medicine 26, pp 35 –43 (2014) http://dx.doi.org/http://dx.doi.org/10.7196/SAJSM.504More Less
Background. Rugby is a physically demanding body contact sport. Optimising dietary intake and body composition can positively affect the performance of rugby players.
Objectives. To determine the body composition, habitual and game-specific nutritional practices of FNB Maties Varsity Cup (MVC) rugby players.
Methods. A descriptive, cross-sectional study with an analytical component was conducted. Of all the MVC rugby players (N=35), 18 completed the sections on body composition and match-day dietary intake, while 11 completed the habitual dietary intake section. Body composition data were collected by an International Society for the Advancement of Kinanthropometry-accredited biokineticist. Habitual dietary intake data (via a self-administered 7-day food record) and match-day dietary strategies (via telephonic 24-hour recall interview) were collected and compared with nutritional requirements reported by the International Olympic Committee, the American Dietetic Association, the American College of Sports Medicine and the International Society of Sport Nutrition.
Results. Forwards had significantly higher weight (p=0.01), sum of seven skinfolds (p=0.01), percentage body fat (p=0.02), fat mass (p=0.01) and fat-free mass (p=0.01) than backs. Compared with current recommendations, group habitual dietary intake (mean (standard deviation)) was inadequate for total energy (45.4 (9.0) kcal/kg body weight (BW)), carbohydrate (4.3 (0.4) g/kg BW), polyunsaturated fatty acids (6.2 (1.7)% of total energy (TE)), calcium:protein ratio (6.5:1 (3.5:1)) and copper (2.3 (0.4) mg), while displaying higher-than-recommended intakes for total protein (2.4 (0.7) g/kg BW), fibre (37.7 (7.3) g/day), total fat (33.8 (4.3)% TE), saturated fatty acids (11.2 (13.1)% TE), cholesterol (766.3 (371.8) mg) and niacin (45.2 (6.9) µg). Habitual supplement use was high at 91% (n=10/11). Nutritional match-day strategies were excessive for protein (1.2 (0.6) g/kg BW) and fat (0.9 (0.4) g/kg BW) in the pre-event meal, inadequate for energy and carbohydrate during the game and excessive for alcohol (54.4 (59.9) g) after the game.
Conclusion. Forwards and backs differed significantly in various body composition measurements. In relation to observed practices, habitual dietary intake and nutritional match-day strategies were suboptimal, with high reported supplement use. Players in this sport potentially could benefit from specialist input to optimise dietary strategies and body composition in order to enhance performance.
Effect of caffeine ingestion on fluid balance during exercise in the heat and during recovery : original researchSource: South African Journal of Sports Medicine 26, pp 43 –47 (2014) http://dx.doi.org/http://dx.doi.org/10.7196/SAJSM.513More Less
Background. The effect of ingestion of a common stimulant, caffeine, on fluid balance during exercise and recovery is not fully known.
Objectives. To determine the effect of caffeine on fluid balance during exercise in the heat and during a 3-hour recovery period thereafter.
Methods. In a randomised, controlled design, caffeine-naive participants (N=8) pedalled on a bike to achieve 2.5% baseline body mass loss in a hot environment in four separate conditions: with (C+) or without (C-) caffeine ingestion (6 mg/kg of body mass) prior to exercise, followed by (W+) or without (W-) 100% fluid replenishment (water) of the body mass loss during a 3-hour recovery period (yielding C+W+, C+W-, C-W+ and C-W-, respectively).
Results. Mean (standard deviation) urine production was not different (p>0.05) regardless of rehydration status: 230 (162) mL (C+W-) v. 168 (77) mL (C-W-); and 713 (201) mL (C+W+) v. 634 (185) mL (C-W+). For the 3-hour recovery, caffeine ingestion caused higher hypohydration during rehydration conditions (p=0.02), but practically the mean difference in the loss of body mass was only 0.2 kg.
Conclusion. In practical terms, there was no evidence that caffeine ingestion in moderation would impair fluid balance during prolonged exercise in the heat or during 3 hours of recovery.
Associations of objectively and subjectively measured physical activity with trabecular and cortical bone properties in prepubertal children : original researchSource: South African Journal of Sports Medicine 26, pp 48 –54 (2014) http://dx.doi.org/http://dx.doi.org/10.7196/SAJSM.507More Less
Objectives. To compare the relationship between peak bone strain scores (PBSSs) calculated from physical activity (PA) questionnaires and accelerometry measures of PA with trabecular and cortical bone properties in prepubertal children.
Methods. We compared PBSSs calculated from the bone-specific component of PA questionnaires with accelerometry and bone mass measures in 38 prepubertal children (mean 9.9 (standard deviation 1.3) years). Dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) were used to assess bone content and structure, and to estimate bone strength at the radial and tibial diaphysis and radial metaphysis.
Results. The PBSS was reliable and reproducible with significant (p<0.001) intraclass correlation coefficients. There were significant correlations between PBSS and moderate (r=0.38; p=0.02), vigorous (r=0.36; p=0.03) and combined moderate- to vigorous-intensity activity counts (r=0.38; p=0.02). PBSS was significantly correlated to body size-adjusted bone mineral content at all sites scanned by DXA (r=0.33 - 0.48; p<0.05). Positive correlations were observed between PBSS and area, density and strength at the radius and tibia (r=0.40 - 0.64; p<0.05). Only vigorous activity was correlated to cortical area at the radial diaphysis (r=0.37; p=0.03) and bone strength at the tibial diaphysis (r=0.32; p=0.05). Activity as assessed by the PBSS explained a greater amount of variance in bone variables as measured by DXA and pQCT than accelerometer-measured PA.
Conclusion. Accelerometer-measured moderate and vigorous habitual PA is associated with indices of cortical bone size and geometry in children, whereas light PA has no detectable association. Furthermore, the bone-specific questionnaire appears to be more strongly associated with bone outcomes than accelerometer-derived measures of PA.
Source: South African Journal of Sports Medicine 26, pp 55 –58 (2014) http://dx.doi.org/http://dx.doi.org/10.7196/SAJSM.526More Less
Objective. The primary aim of this study was to quantify the prevalence of overweight and obesity among urban 7 - 10-year-old children in affluent (quintile 5) English-medium primary schools in Port Elizabeth.
Method. A quantitative, descriptive one-way cross-sectional research design utilising random sampling was used. A once-off survey consisted of anthropometrical assessment of body mass index (BMI) according to standardised procedures. To classify children into weight categories, the International Obesity Task Force z-score BMI cut-off criteria were used. Post-hoc analysis consisted of one-way analysis of variance and X2 tests. Level of significance was set at p<0.05. A total of 713 children participated in the study.
Results. Overweight prevalence was 20.9% (n=149) and obesity prevalence was 9.8% (n=70). A significant interaction was found for overweight and obesity levels by gender and age (F=7.2, p=0.01). Of the boys (N=372) 18.5% (n=69) were overweight and 6.9% (n=26) were obese. The girls (N=341) had a 23.5% (n=80) overweight rate and 12,9% (n=44) were obese. The highest prevalence of overweight (24.7%, n=43, N=174) was found in children aged 10, and the highest prevalence of obesity (12.5%, n=21, N=167) was found in children aged 8.
Conclusion. Results highlighted the rising prevalence of overweight and obesity among urban children from economically privileged settings. Future research into paediatric obesity is needed to curb the growing incidence.
Source: South African Journal of Sports Medicine 26, pp 59 –61 (2014) http://dx.doi.org/http://dx.doi.org/10.7196/SAJSM.552More Less
Dietary supplements and chemical agents have been used for a number of decades among athletes striving to achieve increased strength and performance. This has led to a huge, growing market for the food supplement industry. The latter's products are classified as 'foods' rather than drugs and are therefore free of the stringent requirements for registration of pharmaceuticals, i.e. no safety and efficacy data are required prior to registration. During the past decade, some dietary supplements have been shown to contain pharmaceutically active components not adequately identified on their package labels. These pharmaceuticals may have unintentionally entered the product or may have been intentionally added. Although the concentrations of these substances may be low and devoid of health or performance-enhancing effects, they may lead to positive doping tests. In Part 1 of this two-part review, a selection of the World Anti-Doping Agency-prohibited illegal stimulants, i.e. ephedrine, pseudoephedrine, sibutramine and methylhexaneamine, are discussed. Certain food supplement labels do mention the presence of natural sources of illegal stimulants, e.g. Ephedra sinica (ephedrine), but do not refer to the chemical entities of ephedrine and its analogues as such. The pharmacological adverse effects of stimulants, in particular those on the cardiovascular system, are briefly reviewed. Suggestions for avoiding these pitfalls are made.
Source: South African Journal of Sports Medicine 26, pp 62 –63 (2014) http://dx.doi.org/http://dx.doi.org/10.7196/SAJSM.547More Less
This case report describes chronic exertional compartment syndrome in the forearm of a professional rower. We consider this to be a rare anatomical location for this type of syndrome. Morever, not much is known about its clinical presentation and the subsequent optimal medical management thereof.