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TRAINING – Gender Perspective
Gender differences in Orienteering;
Introduction
THERE are many examples of discrepancies in the physical demands of sporting events undertaken by men and women, even within sports. For example, in major tennis championships men play the best of 5 sets and women the best of 3, in golf women are able to use a tee that is slightly closer to the hole, and it was only in 1984 that the Olympic Games first included a women’s Marathon. In our own sport of Orienteering, a quick glance at the course details for an event will show that for all the age groups, barring perhaps the very youngest and oldest, women orienteers have shorter courses than their male counterparts. By way of example, in the 2007 Australian Championships, the women’s long courses were on average 23% shorter than the men’s. This article will attempt to evaluate whether the observed differences in course length can be justified on physiological basis. This can be a very emotive subject so I would like to establish a couple of points before becoming the target of irate letters. Firstly, in no way does the physiological evidence, or for that matter orienteering results suggest that men and women of the same age couldn’t do the same courses. But what the evidence does suggest is that there should be separate male and female categories, as is the case, and that perhaps by having different length courses for men and women of the same age, the planner is providing an event in which the relative physical demands are the same. To discuss this I’ll present an overview of some of the pertinent physiological differences between sportsmen and sportswomen. In doing so it is clearly evident that there is considerable variation within each gender, and considerable overlap. So, when making these physiological comparisons I’ll be comparing like with like, that is to say top W21E females with top M21E males, or top W40 females with top M40 males, and not elite W21E females with less fit M21 males, the former of whom are likely to have a superior level of fitness and performance than the later. Additionally, it is appreciated that orienteering isn’t just about physical fitness. Navigational skills and the mental sporting attributes of the individual are also of vital importance. But since I am not sufficiently familiar with any research that compares these factors in male and female orienteers, I will leave it to others who are better informed to comment on them. Additionally, I’m also cognisant of the strong influence of historical factors and society’s beliefs of what men and women are physically capable, but will again leave that to others for comment.
In endurance running events of between 15 and 150 minutes, the times recorded by the men are generally around 10% faster than those of the women, with a similar difference being evident from club to world standards. Therefore, given the endurance running nature of orienteering, we may expect to see a similar difference in orienteering performance. Indeed research seems to suggest that this is the case3, and to provide a recent example I conducted a very basic comparison using the results of the Australian 2007 Long Distance Championships. For this I took the top course for each age group, which provided 14 pairs of long courses from 12A to 75A, and the time taken by the first 3 men and first 3 women on each of these courses. I then calculated the average time taken for the top 3 men and top 3 women to complete their courses, and finally converted this into orienteering speed (m/sec) by dividing course distance (m) by time taken (sec). The results are illustrated in Figure 1.
Such a rough comparison is obviously prone to a few anomalies, but nevertheless seems to support the general assertions made above, with the women’s orienteering speed being approximately 80% of the men’s across all age groups. Incidentally, the failure to get a smooth decline in speed with age is probably due to the better older orienteers continuing to run in the younger and elite classes. There may also be a few course discrepancies in terms of climb and relative time spent in fast or slow terrain. But
Figure 1
Steve Bird
nevertheless as previously indicated, for such a gross analysis the results appear quite compelling. So, why do these differences exist, and are the current differences in course lengths justifiable?
Prior to puberty there is virtually no difference in the physical capacities of boys and girls, indeed the girls may actually move ahead of the boys for a few years before the males enter puberty. After this point the greater levels of anabolic hormones, including testosterone, in males stimulate larger improvements in many of the physiological factors that are associated with fitness. The physiological adaptations to training are virtually identical in males and females but because of certain gender and hormonal related differences the final values attained by males tend to be higher, and for those who wish to read further into this I’ve listed a few references at the end of this article 4,5,6. The key fitness components in Orienteering are a person’s capacity to utilise oxygen (VO2max), and a number of related factors that ultimately dictate the running speed that a person can sustain for a prolonged time. VO2max is determined by a combination of a person’s capacity to get oxygen into their lungs, transport it around their body to the exercising muscles, and their muscles’ capacity to utilise the oxygen when it’s delivered. It is therefore a complex and multi-staged process, and one in which the capacity of males and females can differ at virtually every stage. On average a female’s lung capacity is less than a male’s. Even when accounting for differences in body size there is still a 10% difference relative to body weight. This means that when exercising strenuously, elite male orienteers may be able to breath in and out 100 - 180 litres of air a minute whilst elite females are capable of ventilating 70 - 120 litres of air. This therefore means that there is a difference in their capacity to get oxygen into the lungs. Once in the lungs the oxygen diffuses into the blood. Here again there are differences between the males and females. Elite females have about 4 - 4.5 litres of blood compared with elite males who may possess 5 - 6 litres. When adjusted for body weight this gives a female about 65ml of blood per kilogram of body weight as compared with a male’s 75ml/kg body weight. Furthermore, there are differences in the relative composition of the blood. In females, red blood cells make up about 42% of the blood volume and contain about 12 -14g of the oxygen-carrying haemoglobin per 100ml of blood. In males the red blood cells make up about 47% of the blood volume and the haemoglobin concentration is about 14 - 16g per 100ml. This means that the elite male not only has more blood with which to deliver the oxygen, but can also carry more oxygen in each litre of blood. In effect, this means that to deliver 1 litre of oxygen to her muscles the elite female needs to pump 9 litres of blood, whereas the male needs to send only 8 litres of blood to provide his muscles with 1 litre of oxygen. The blood is sent around the body by the pumping action of the heart. A female’s heart is approximately 15 - 20% smaller than a male’s of the same body weight. This means that it has to beat more often in order to send the same amount of blood around the body. Since there appears to be no significant difference in the maximum heart rates of males and females, the overall effect of this means that during strenuous exercise the elite female cannot deliver as much blood, and therefore as much oxygen, to her exercising muscles as her male counterpart. Consequently, elite male orienteers are likely to be able to deliver and utilise in excess of 5 litres of oxygen per minute (70 - 80 millilitres of oxygen per kg of body weight) as compared with elite female orienteers whose values are likely to be around 4 litres of oxygen (60 - 70ml/ kg/min). And because of the link between running speed and the muscles’ need for oxygen, this means that the males can sustain a faster running pace. Another factor that affects endurance running performance is body composition. The human body is made up of water, lean tissue (bones, muscles and various organs) and fat. Fat serves many important purposes within the body; it provides insulation, protects vital organs, is needed in the synthesis of certain chemicals and provides a large source of energy. However, above a certain amount, the fat in the body simply becomes an excess burden which does not contribute to any useful function in the context of orienteering or other running events. Despite the fact that fat is a useful source of energy for running, an excess of fat is not likely to provide any extra energy during an orienteering event. This is because even the very fit, lean endurance runners have enough fat to complete a marathon distance many times, and it is not a lack of energy in the form of fat which limits their running speed, but other factors such as the depletion of muscle glycogen. So carrying additional fat is of no advantage and is simply extra weight, which explains why the top runners, including orienteers tend to be lean. Of course too little fat can also cause problems with fitness as well as health and it is important to attain the right level for
optimum performance. When comparing the male and female body composition, the average male’s body is about 18 - 23% fat whereas a female’s is 28 - 32% fat. This difference is in the form of gender related fat which is deposited at various sites around the female’s body. The extra fat tissue that the female possesses is additional weight, which she must carry. Even in the leanest of orienteers this difference in body composition still exists with the males getting as low as about 6 - 8% fat and the leanest females 11 - 16% fat; which is somewhat leaner than many males, but still not as lean as her elite male counterparts. Simplistically this means that when comparing elite females with elite males, the elite female may be carrying an extra 5 - 10 kgs of fat, which would be like asking an elite male to run an event carrying a 5 – 10kg ruck-sac. Other differences between males and females include the average male being slightly taller with a longer stride length. This may be an advantage when crossing rough terrain but in reality the significance of this, if there is any, may be very slight. If it was significant then we might expect all our top female orienteers to be tall, which is not the case. Another difference between the average male and female is the amount of muscle. Elite males may possess 10 – 15kg more muscle than elite females, but unlike fat, the additional muscle tissue contracts to provide the power for running and is not therefore an inert additional weight burden. So in summary, much of the observed differences in orienteering speed between men and women can be explained by differences in their capacity to deliver and utilise oxygen, and their percentage body fat.
As mentioned above, the courses for women orienteers tend to be shorter in length than those for men of the same age. However when we compare the time taken to complete their courses (using the top 3 from each course in the 2007 Australian Championships as an example), the finishing times for men and women of the same age group vary from 76% to 140% of the men’s time (Figure 2). And on average these time differences averaged out over the 14 pairs of courses, so that on average the women took exactly as long as the men.
This means that on average, the top men and women in each age group are taking about the same amount of time on their courses. Physiologically, this is probably an ideal finding, as it means that the men and women are being subjected to similar physiological demands. That is to say that although their absolute orienteering speed and distance run will differ, their relative intensity will be very similar, and for a similar duration. So from the evidence above it would seem that offering separate male and female competitive categories is justifiable, as is the practice in Orienteering and most other sports. Additionally, whilst there is clear evidence that women orienteers could do the same courses as the men, with the best beating many of the men, the physiological evidence suggests if we were to offer the same course lengths, the planner would be setting a somewhat more physically demanding challenge for the women, as they would be required to run for a longer duration. So from a practical perspective, the fairest way to set a similarly demanding challenge is to set course lengths that have the same predicted winning time. By doing so the planner will be setting the same relative physiological demands for the same duration, thereby making the challenges of the men’s and women’s courses as equitable as possible.
Figure 2 Conclusion
In reality, our current system utilises the variety of course lengths that are provided in response to age associated declines in fitness, with the older men undertaking the same courses as women around 10 – 20 years younger. In doing so we may not have the relative duration exactly matched, as indicated in Figure 2, where some women’s age classes took considerably longer than the men’s and others considerably less. But to be more precise would require many more courses and far greater difficulties for the planner. And so given the practicalities of trying to minimise the total number of courses a planner has to produce for an event; the economies that are currently achieved by having men and women of different age groups running the same course, may well be the best option. And if we use Figure 1 as a rough approximation, to have the older men run the courses of the women about 15 years their junior is probably about right. Although in the words of Abraham Lincoln, I’m sure it’s a case of, “You can’t please all of the people all of the time”.
References
1. Bird S (2004). Orienteering Fitness (Part 1). Australian Orienteer, no. 136, December 2004, p48. (ISSN 0818-6510) 2. Bird S (2005) Orienteering Fitness (Part 2). Australian Orienteer, no. 137, March 2005, p30. (ISSN 0818-6510) 3. Bird S, Balmer J, Olds T and Davison RCR (2001). Differences between the sexes and age-related changes in orienteering speed Journal of Sports Sciences, 19, pp243-252. 4. Koutedakis, Y and Sharp, C. British Journal of Sports Medicine, Volume 25 (4) pp188 - 190, 1991. 5. McArdle, W., Katch, F., & Katch, V. 2006, 6th Ed. Exercise Physiology, Energy Nutrition and Human Performance 6. Powers, S., & E. Howley, 2006, 6th Ed. Exercise Physiology Theory and Application to Fitness and Performance - McGraw Hill Publishers.
Professor Steve Bird is at RMIT University, Melbourne. Steve worked with the Great Britain National Orienteering Squad for over 10 years and is now assisting the Victorian Junior Squad.
