SAJSM 2001 No.1
South African Journal of Sports Medicine
■ The contents of the first edi tion o f the South A frican Journal o f Sports Medicine for 2 0 0 1 reflect the multi-dis cip lin a ry nature o f sports m edicine. The study by Nurok and colleagues on the ath le tic a bility o f young Kenyan athletes reaches the conclusion that the superior running a bility o f the K enyans can perhaps be explained by specific inheri ted characteristics. However, it is a difficult theory to prove and it is going to take many more studies in disciplines rang ing
... from sociology to molecular biology and genetics before we can conclude with confidence that factors governing suc cess in athletics are inherited. The study by Weston and her colleagues on heart rate as a marker o f exercise intensity during mini-trampoline exer cise contributes to the knowledge in the field o f applied exer cise physiology. This study show s th a t the oxygen consumption/heart rate relationship during mini-trampoline exercise is not always linear. Clearly, under these conditions heart rate is not an accurate marker of exercise intensity and therefore should be used with caution in prescribing exer cise. This study once again exposes the predicament that we have in the fields of sports medicine and exercise physiolo gy. For example, on the one hand we have devices for mea suring heart rate which are highly sophisticated and can measure heart rate under free living conditions with a high degree o f accuracy. Furthermore, the heart rate data can be stored for several days before being transferred to a com puter for analysis. On the other hand we have an emerging understanding of how heart rate changes during exercise under various conditions. We know that factors such as environmental temperature, state o f hydration, mode of exer cise, duration of exercise and competition all have a signifi cant effect on the heart rate/exercise intensity relationship. More recently it was shown that as physical fitness increases, maximum heart rate decreases (Zavorsky G S. Evidence and possible m echanism s o f altered heart rate with endurance training and tapering. Sports Med 2000; 2 9 :13 -26.) This finding has important implications in the health industry where exercise participants are encouraged to monitor their training intensity according to their heart rate expressed as a percentage of maximum heart rate. Clearly if the decrease in maximum heart rate with increasing fitness is not taken into account, then the relative intensity o f the training sessions will become harder and harder as fitness improves. In sum mary, the study by Weston and her colleagues is important in that it contributes to narrowing the large gap between the technical capabilities of heart rate monitors and the under standing of how heart rate responds to exercise. This gap has to be narrowed even further before heart rate monitors can be used to their full potential. The study by Marino and Booth addresses the question of whether precooling before endurance exercise in moderate and high environmental temperatures has any ergogenic effect. Research into this area is fascinating for two reasons. Firstly, the underlying physiological mechanisms o f the 'pre cooling' effect are not fully understood. Secondly, the applied spin-offs of this research may result in marathon race organ isers moving their jacuzzis to the start of the race rather than the end! The article on the popliteal vascular entrapment syn drome describes a possible cause of leg pain in young ath letes. This article points out that the syndrome is more prevalent than previously believed and that a late diagnosis can have serious consequences for the patient. In contrast, an early diagnosis and surgical correction result in prompt and lasting relief of the symptoms. This article will surely contribute significantly to more clinicians making the correct diagnosis of the condition thus sparing their patients much discomfort, frustration and expense. Identifying the competitive edge in sport is always a pop ular topic. Therefore the article on creatine supplementation will be interesting for a wide range of readers. Although the study in this journal focussed primarily on the performancerelated effects, the side-effects that a large proportion of the subjects experienced in this study should not go unnoticed. In summary, this edition of the Journal should have something of interest to cater for the needs of all the health professionals and scientists who belong to a multi-discipli nary sports medicine association. This Journal is a vehicle for new ideas in sports medicine. You are encouraged to read it, enjoy it and hopefully learn something which can be used to improve performance and reduce the risk of injury!