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- Volume 16, Issue 2, 2004
South African Journal of Sports Medicine - Volume 16, Issue 2, 2004
Volumes & issues
Volume 16, Issue 2, 2004
Author Mike LambertSource: South African Journal of Sports Medicine 16 (2004)More Less
Extracted from text ... The second issue of the South African Journal of Sports Medicine in 2004 coincides with an exciting time of the year for sporting events. This is the time for the Comrades marathon, Berg River canoe race, Tour de France, European Cup and Wimbledon - all great events with a rich history. The new international rugby season begins for South Africa while the athletes from various sporting codes prepare themselves for the Olympic Games. While this is a busy time of the year for the competitors in the various events, it is also a busy time for the support staff ..
Source: South African Journal of Sports Medicine 16, pp 3 –7 (2004)More Less
<I>Objective.</I> Inadvertent doping through the use of nutritional supplements is a potentially important cause of the increase in positive drug tests involving high-profile Olympic athletes. The aim of this study was to screen over-the-counter nutritional supplements for the presence of steroid or stimulant compounds banned by the International Olympic Committee (IOC) and the World Anti-Doping Agency (WADA). <br><I>Method.</I> Thirty different nutritional supplements from 14 different manufacturers were bought at shops in Bloemfontein, South Africa and analysed for testosterone and nandrolone prohormones, various ephedrines and caffeine. <br><I>Results.</I> Eighteen (60%) of the 30 supplements contained no prohibited substances. Of the 12 (40%) positive supplements, 8 (66.7%) contained prohormones and 4 (33.3%) contained stimulants. Six supplements contained prohormones, which were listed on the labels, while 2 contained prohormones not listed on the labels. The stimulants were listed on the labels as Ma Huang, Guarana and Kola extracts and all contained a mixture of ephedrines and caffeine. <br><I>Conclusion.</I> The results showed that approximately 7% of supplements tested may be mislabelled or contaminated with banned substances and that inadvertent doping through nutritional supplement use is a reality for athletes. The sporting community should therefore be aware that supplements might contain anabolic androgenic steroids and stimulants that are not declared on the labels.
Source: South African Journal of Sports Medicine 16, pp 8 –11 (2004)More Less
<I>Objective.</I> This study examined age-related decrements in athletic performance during running and cycling activities. <br><I>Design.</I> The age group winning times for males aged between 18 and 70 years competing in the 1999 Argus cycle tour (103 km) and 1999 Comrades running marathon (90 km), South Africa's premier endurance cycling and running events respectively, were examined. <br><I>Main outcome measures.</I> The relationship between speed (cycling and running respectively) and age was calculated using a 4th order polynomial function. The derivative of each of these functions was determined and then the slope of the function corresponding to each age was calculated. <br><I>Results.</I> The rate of decline in running speed occurred at an earlier age (~ 32 years) during the running race compared with the cycling tour (~ 55 years). <br><I>Conclusions.</I> These findings establish a trend that there is 'accelerated' aging during running which can perhaps be attributed to the increased weight-bearing stress on the muscles during running compared with cycling.
Non-allergic activation of eosinophils after strenuous endurance exercise : original research articleSource: South African Journal of Sports Medicine 16, pp 12 –16 (2004)More Less
<I>Objective.</I> To determine the effect of prolonged endurance exercise on the serum concentrations of eosinophil cationic protein (ECP), immunoglobulin E (IgE) and upper respiratory tract symptoms (URTS). <br><I>Design.</I> In 11 healthy, experienced volunteers (6 males, 5 females, age 43 <u>+</u> 9.8 years) the serum concentrations of ECP and IgE were measured, 24 hours prior to projected finishing time, immediately post exercise (IPE), and 3 h, 24 h, and 72 h after an ultramarathon (90 km). Self-reported URTS were also recorded for 14 days after the race. ECP was measured using radioimmunoassay and IgE using the Alastat Microplate Total IgE kit. The after-exercise values were corrected for plasma volume changes, which were calculated from haematocrit and haemoglobin values. Serum concentrations of ECP and IgE were analysed using an analysis of variance (ANOVA) comparing values with before-exercise levels. Level of significance was set at <I>p</I> <u><</u> 0.05. <br><I>Results.</I> ECP was significantly elevated at 72 hours (+52%), whilst IgE was not significantly altered after the ultramarathon. There were no reported URTS for the 14 days after the race. <br><I>Conclusion.</I> The eosinophil is a pro-inflammatory leukocyte involved in bronchial hyperreactivity and allergic inflammation of the airways. IgE is associated with allergic diseases such as asthma and rhinitis. Serum ECP is a sensitive marker of eosinophil activation. The result provides evidence for the non-allergic activation of blood eosinophils during prolonged endurance exercise. Whether this indicates exercise or environmentally induced airway inflammation, or a role for ECP in muscle /tissue repair, are hypotheses that require additional research.
Alterations in acute-phase reactants (CRP, rheumatoid factor, complement, Factor B, and immune complexes) following an ultramarathon : original research articleSource: South African Journal of Sports Medicine 16, pp 17 –21 (2004)More Less
<I>Objectives.</I> The human body initiates an acute phase response (APR) in response to a wide range of homeostatic disturbances. This complex series of reactions serves to activate repair processes and prevent ongoing tissue damage. An important aspect of the APR is the <I>de novo</I> synthesis of acute phase proteins (APP), many of which have not been thoroughly investigated. <br><I>Main outcome measures.</I> Alterations in CRP (C-reactive protein), C1est, C3, C4, C6, rheumatoid factor (RF) and Factor B were determined before and after an ultramarathon. Data were analysed using a one-way analysis of variance comparing values to pre-exercise levels. Significance was set at <I>p</I> < 0.05. <br><I>Design.</I> Venepunctures were performed on athletes participating in an ultramarathon (90 km) 24 hours before, immediately post-exercise (IPE), and 3h, 24h and 72h after the race. Serum was stored at -80<sup>o</sup>C until analysed. CRP levels in serum were assessed using the N Latex CRP kit. The levels of circulating immune complexes (CIC) were determined using particle-enhanced nephelometry. Complement proteins C1est, C3, C4 and RF were measured using laser nephelometry. C6 and Factor B were determined by radial immunodiffusion. <br><I>Results.</I> CRP was significantly elevated IPE (58%), 3h post (77%), 24h post (87%) and 72h post (69%). Pre-race CRP levels were above the normative range (5.10 <u>+</u> 3.08 mg/l), C6 was significantly elevated (<I>p</I> < 0.05) at 24h post (7.8%) and 72h post (8.8%) exercise. Factor B was significantly elevated (<I>p</I> < 0.05) at 72h post exercise (12.8%). RF was significantly elevated at 72h post exercise (6.7%). <br><I>Conclusion.</I> Significant increases in selected acutephase reactants occur several days after the exercise event. In addition, as indicated by elevated resting levels of CRP, the athletes began the race with some degree of inflammation, presumably as a result of the cumulative training and racing mileage in preparation for the ultramarathon.
The effect of a professional cricket match schedule on selected immune parameters : original research articleSource: South African Journal of Sports Medicine 16, pp 22 –27 (2004)More Less
<I>Objective.</I> The impact of a professional cricket match schedule on white blood cell (WBC) distribution and lymphocyte activation (CD69 expression) was investigated. <br><I>Methods.</I> After a 3-month pre-season training period, physical and immune parameters were determined in 14 male cricketers before (B) and after (A) an intensive 5- week match schedule. <br><I>Results.</I> Exercise test results were unchanged from B to A. Total WBC counts were similar, but total lymphocyte and lymphocyte subpopulation counts decreased significantly. The CD4:CD8 ratio did not change. After <I>in vitro</I> stimulation, percentage CD4+CD69+ cells increased (B: 54.4 <u>+</u> 9.7%, A: 64.0 <u>+</u> 8.5%, <I>p</I> < 0.01), but absolute CD4+CD69+ cell counts did not change from B to A. In contrast, both the %CD8+CD69+ cells and absolute CD8+CD69+ cell count remained similar. <br><I>Conclusion.</I> A strenuous, interregional, professional cricket match schedule resulted in a decreased number of lymphocytes, but relatively increased <I>in vitro</I> reactivity of CD4+ cells, thus maintaining the absolute capacity of the CD4+ cells to become activated on stimulation. In cricketers who suffered upper respiratory tract symptoms during the match schedule (<I>N</I> = 7), none of the immune parameters investigated differed significantly from the others at B or A.
Source: South African Journal of Sports Medicine 16, pp 28 –32 (2004)More Less
Prolonged, strenuous exercise results in muscle glycogen depletion. Recovery of these stores prior to the next training session or competition is crucial to optimise exercise performance. Nutrition plays an important role during the post-exercise recovery period when processes such as muscle regeneration, glycogen and fluid restoration take place. By manipulating the timing, type and frequency of food intake the rate of recovery can be enhanced, which is of particular importance to athletes performing multiple training or competition sessions within a day, or on a dayto- day basis and recovery time is limited. Restoration of muscle glycogen stores is especially important for athletes participating in prolonged exercise, since depleted glycogen stores are associated with impaired exercise performance. Key factors affecting muscle glycogen storage are carbohydrate (CHO) availability and an increased insulin concentration, both of which are influenced by amount and timing of CHO intake, type of CHO ingested, the ratio of CHO to protein ingested, and the fat content of a food item or meal. To maximise the rate of muscle glycogen restoration during a short (< 6-hour) recovery period, 1 - 1.5 g moderate to high glycaemic index CHO/kg body weight (BW) immediately post-exercise, followed by 0.8 - 1.5 g moderate to high glycaemic index CHO/kg BW/hour (divided in smaller doses every 15 - 60 minutes) for 3 - 4 hours should be ingested. With a longer recovery period (<u>></u> 6 hours) muscle glycogen storage is independent of type of CHO ingested but a total of 7 - 10 g CHO/kg BW should be taken in within a 24-hour period. Combining protein with an adequate amount of CHO (> 1 g/kg BW/hour) has no added advantage in terms of enhanced rate of glycogen storage, but can be of practical importance. Additionally, this combination may be beneficial since CHO and amino acid availability are important for muscle repair during the recovery period, as will be discussed in detail in Part II of this article.
Source: South African Journal of Sports Medicine 16, pp 33 –40 (2004)More Less
A net positive nitrogen balance is needed for exerciseinduced muscle damage to be repaired during the recovery period. Apart from hormones and growth factors, adequate energy and amino acid availability contribute to this balance and influence the rate at which protein synthesis and muscle repair occur post-exercise. This paper reviews the dietary factors involved in muscle repair during the post-exercise recovery period. Both resistance and endurance-trained athletes have a higher dietary protein requirement of between 1.2 and 1.8 g protein/kg body weight (BW)/day, with an upper limit of 2 g protein/kg BW/day. To increase the rate of protein synthesis during the recovery period, immediate ingestion of protein postexercise is recommended. Additionally, ingesting 1.2 g carbohydrate (CHO)/kg BW/hour with 0.4 g/kg BW/hour of a wheat amino acid mixture (wheat protein hydrolysate combined with free leucine and phenylalanine) enhances the insulin response compared with ingesting CHO only or combined with other protein hydrolysates, peptides, or intact protein. This increased insulin response could increase muscle protein synthesis indirectly by altering the hormonal milieu. Results on the anabolic effect of single or mixtures of amino acids remains to be further elucidated. The possible antioxidant benefits of whey protein supplementation in athletes remains to be proven, while the antioxidant potential of soy protein holds promise. The effect of glutamine supplementation on protein synthesis in athletes is limited and its clinical relevance for enhanced immune function in endurance athletes remains to be established. Creatine supplementation seems to be beneficial in terms of protein synthesis and gains in fat free mass during the recovery period, while the use <SPAN lang=AF style="FONT-FAMILY: Symbol; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-char-type: symbol; mso-symbol-font-family: Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font: Symbol">b</SPAN></SPAN>-hydroxy <SPAN lang=AF style="FONT-FAMILY: Symbol; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-char-type: symbol; mso-symbol-font-family: Symbol"><SPAN style="mso-char-type: symbol; mso-symbol-font: Symbol">b</SPAN></SPAN>-methylbutyrate (HMB) supplementation by trained athletes seems to have limited benefits. It is important to keep dietary advice individualised considering the complexity in which the endocrine system regulates cell function, the diverse mechanisms that control homeostasis, as well as genetic variability.
The effect of prophylactic knee bracing on proprioception performance in first division rugby union players, South African Journal of Sports Medicine, 16 (1) 2004, pp.33-36 : erratumSource: South African Journal of Sports Medicine 16 (2004)More Less
Extracted from text ... 40 Erratum An unintentional error resulted in the degrees for T H Kruger, M F Coetsee and S Davies (South African Journal of Sports Medicine 2004; 16: 33) being listed incorrectly. Their correct qualifications are: T H Kruger (BSc Hons Human Movement Science (Biokinetics), MSc (Human Movement Science)) M F Coetsee (MA (Physical Education), PhD) S Davies (B Hum Hons (London Univ), MA (Human Movement Studies), DPhil ..