Mind Games Food may have the power to affect your mood Our mind is a complex, interactive process. In some cases, food and chemicals can influence our mood and behaviour. In addition, it would appear that some of us might be genetically prone to unstable moods and depression. Triggers to imbalanced moods ♦ High intake of stimulants like caffeine eating foods that we might b
Pp194.pdfto try to reduce its impact on the players’ ‘Underperformance
players as 30% of team sport players aged 16-20 syndrome’: how youth
suffer from staleness(3). Such athletes face often- conflicting pressures from teachers, parents, rugby coaches are using coaches, peers, relationships, work and training, African running
which can lead to staleness, burnout and injury(4). psychology to raise
What do we mean by these terms? Short-term their players’ game
overtraining, known as ‘overreaching’, can be seen as a normal part of athletic training and In professional sport, coaches are under intense pressure to perform. In the final game of the overtraining that can lead to burnout, staleness, English domestic Rugby Union season in 2003, or ‘overtraining syndrome’(5). Staleness can be Saracens played Leicester, with the winner distinguished from burnout by the athlete’s offered a chance to play in the European Cup the motivation to train; while the symptoms may be following season, an opportunity worth about similar, a stale athlete is still motivated to train £250,000 in extra gate receipts and sponsorship and a burned-out athlete is not (6).
money for the club. Saracens lost, and the entire Because of the many potential causes of poor coaching staff was sacked, having been in place performance, overtraining syndrome (OTS) has recently been redefined as the ‘unexplained underperformance syndrome’ (UPS). It can be performance by increasing training load(1), which distinguished from overreaching by the fact that may actually exacerbate the problem rather than symptoms do not diminish after two weeks of solving it. Underperformance can be caused by a rest(7). However, these terms will be used number of factors, including injury, fatigue, loss interchangeably in this article because of their of confidence or motivation, relationship problems (within or outside the team), and other Preventing UPS calls for a careful balance of external stressors, such as exams, career or training stimulus and recovery – the latter defined as ‘a well-planned activity that matches the situational needs of an athlete in rest and results in regaining an optimal performance differently to the stimulus. What may be optimal state’(8). However, training is much easier to for one may be too much for the other. The same manipulate and measure than recovery because could be said for an individual who responds of the difficulty of accurately recording and differently to the same workload in two different training cycles. The key factor here may not be Nevertheless, having an accurate measure of the workload, but something else going on in that recovery may be useful to a coach because he or she can then identify any problems that may be Rugby Union is a sport where the physical preventing the athlete from achieving peak demands are high through exertion and from contact. The English domestic season lasts from Any such measure must also be affordable and late August to early May. Keeping players in a easy to use in order to work in the coaching physical state that allows for peak performance environment. This may be especially true when week after week is difficult(2); ensuring their working with youth athletes, where budgets tend physical and mental recovery is even more What measures have been used to date – and In my role as conditioning coach at London how effective have they been? Heart rates which Welsh Rugby Football Club, I have had the are elevated in the morning and reduced during opportunity to measure and assess the amount of fatigue associated with training and lifestyles and indications of OTS(9-13). But this has not been found in all studies, including those on: judoka(14), wanted to know whether this was due to a drop in cyclists and triathletes(15), swimmers(16,17), and runners(17,18,19). In one study, individual differences in resting heart rate were found in overtrained When we looked back on the first season’s runners, calling into question the reliability of one scores, we saw remarkable differences between marker as an accurate measurement of OTS(20). those players who had consistent performances This particular marker is also dubious because and went on to representative honours at age- resting morning heart rates are known to be group level and those whose form slumped, or reduced by a good night’s sleep(21), and none of the studies that noted elevated resting heart rate in overtrained athletes took sleep into account as statistical analysis of the Rest-Q scores on the Academy as a whole, looking at stress and recovery scores, injury prevalence, physical Markers of excessive training
fitness and playing performance. This did not Usitalo et al could not find a universal pattern of physiological responses to excessive training, I then divided the players into four main which appears to be the main problem at present: categories: players who performed well; those no one physiological marker is reliable for all who suffered from burnout; those who suffered athletes, while relying on a combination of markers may not accurately distinguish between fitness levels and performances were consistent overreaching and OTS. The only consistent factor throughout the season, and who didn’t get is a decline in the athlete’s performance(22).
injured. By homing in on individual players in Psychological measures have been proven to more detail, we hoped to see trends that were be as effective as physical measures in diagnosing common to the groups. Two of the individuals are ‘training stresses’(23). Could these also be useful presented as case histories here: Player A, who performed better than expected, and Player D commonly-cited tool is the Profile of Mood States questionnaire (POMS), which, as its name Player A’s graph (figure 1, below) shows high suggests, measures moods. However, moods are levels of recovery and low levels of stress at test 1 highly contagious among athletes, with highly and at test 6 (pre-season and end of season). He motivated athletes and women seeming to be at also shows higher levels of success, social recovery, higher risk. Thus, this may be a less useful tool in physical recovery, personal accomplishment, self- a team environment and is also considered efficacy and self-regulation at test 6 than at test 1.
unreliable as an indicator of staleness(24).
He was selected for the Wales under-19 squad for A more recent psychological tool is the Rest-Q – the Recovery-Stress questionnaire for athletes, This player lived at home, and his dad attended devised by Kellmann and Kallus(25), which asks all the training sessions and matches throughout questions about the athlete’s current state of recovery and stress. This tool attempts to Figure 1: player A’s Rest-Q scores at both ends
integrate the useful parts of the POMS into a of the season
more functional assessment of an athlete’s current training status. It uses 19 scales relevant in the recovery process, such as general stress, self-efficacy and emotional exhaustion, and has been demonstrably effective in monitoring training dosages in elite training camps(26,27). As part of my work with London Welsh RFC, I have been using the Rest-Q for the last two seasons to monitor levels of recovery and stress in the academy players, in conjunction with their physical fitness. My aim was to see if the Rest-Q, administered throughout the season at intervals of 6-8 weeks, would be useful in preventing underperformance in a semi- professional, part- time training environment, similar to many On the recommendation of the tool’s author, we measured physical fitness at the same time as measuring psychological wellbeing with the Rest-Q; if a player was in a bad physical state, we Figure 2: player D’s Rest-Q scores in two pre-
season tests four weeks apart
East African running
– a new perspective
PP, as regular readers will know, keeps a weather eye on the scientific journals so we can keep you abreast of the latest significant findings on all things relevant to sport performance. Usually we are happy to précis the most interesting of these reports in our ‘What the Papers Say’ section: let’s face it, a lot of the material in these papers would be gobbledegook to a non-scientist anyway! But this month a fascinating – and unusually readable – original article published in the British Journal of Sports Medicine beguiled us to such an extent that we decided (with the permission of the publishers, of course) to reprint it in its entirety, The article, which begins on p5, represents an important contribution to the growing debate on the season. Social support has been shown to the indisputable East African dominance of contribute to health and wellbeing by reducing middle- and long-distance running. Thus far, the exposure to stress and enhancing coping efforts(28).
thinking has polarised between the genetic theory He was studying at school, but did not work to – East Africans have an inbuilt racial advantage – earn money. This may have been a significant and the environmental theory – they live at high reason for his continued success, enabling him to altitude and also tend to run very long distances to concentrate on his rugby and recover at home.
Player D’s graph (figure 2, above) shows minor But Canadian scientists Baker and Horton have differences during the two pre-season tests, with advanced a rather more subtle psychological test 2 carried out four weeks after test 1 and four theory: the East Africans run faster because weeks before he dropped out of the academy.
everyone tells them they have a natural aptitude for running faster and therefore they believe they wellbeing score lower in the second test, but self- can run faster. And the white runners come a poor efficacy and self-regulation score higher. In a second for the self-same reasons. Baker and follow-up conversation this player expressed Horton call this phenomenon ‘stereotype threat’; dissatisfaction with his own performance and said you and I might call it a self-fulfilling prophecy.
he had been consistently under pressure at work Does it matter? Well, yes it does, because the as an apprentice. He cited his early morning starts long-term effect of this stereotype threat is as a main reason for not being able to recover discouragement, demotivation and, ultimately, from training the previous evening. He lived with his parents and had few household chores and handicap is a set of false beliefs. We urge all little homework to contend with, but his parents athletes and coaches to note the conclusions of did not show any overt signs of support for him this article – and act accordingly.
within the rugby environment. This may have Also in this issue, new PP contributor James been a significant factor in his decision to drop Marshall writes about how he used a psychological out from the sport, as people who have weak social ties, including those with their immediate ‘underperformance syndrome’ in young rugby family, have been shown to have weaker health players (p1); and our regular nutrition guru than those with strong social ties(29).
Compared with previous research using case supplements to boost your natural immunity and studies(25,26), this study showed the importance of external influences on each player. For example, Kellmann used the Rest-Q to highlight the Three lengthy articles – and an awful lot to relationship between an increase in training dose digest. But we hope you will agree this issue offers and increased stress and decreased recovery in rowers. But as these athletes were attending a Isabel Walker
full-time training camp, external influences logistics of testing a total of 81 players, inputting The two major adverse external influences my and analysing the data, meant that a quick research uncovered, were living away from home response was not always available to individual and playing for additional teams. The effects of players. Also, the exercise only picked out those living away from home could have been due to players whose profiles changed significantly missing the structure and support associated with between tests, which meant that some players on both the school and home environments(29,30,31). the road to UPS were overlooked. The Rest-Q is The influence of non-athletes in the university not a substitute for good communication between the coach and his individual players. But we have freedom and lack of accountability for the first found it to be very useful for analysing each player few months, could have created a new ‘perceived and feeding back information which might be social norm’, in which training and good dietary affecting performances as quickly as possible.
and sleep habits were of secondary importance to With one season of players’ histories available to us and a greater understanding of the areas to indicators of adherence to training programmes: accurate in the current season. After identifying training partners, social support, time and the main areas of concern, several changes have opportunities, self-efficacy, and perceived been made. I as conditioning coach have taken vulnerability. While players at university had responsibility for educating players, parents and plenty of time and opportunities to train and play, coaching staff on the need for a balance between as well as access to training partners, their training and recovery. An eight-week training recovery habits were poor, with too little quality macrocycle has been put in place, comprising two four-week training blocks, with the last week of structure. This led to inconsistent or deteriorating performances that could result in burnout.
Testing, including the use of the Rest-Q, takes place on completion of the second recovery Advantages of living at home
Players living at home, either studying for A- levels or in full-time employment, had less time recommended to see their doctors to eliminate and opportunity to train, but generally had better the possibility of clinical illness. Many of the social support and recovery habits, which led to more consistent playing patterns throughout the depression(34), so it is important for those doctors season. Despite their work pressures, players to have some knowledge of the syndrome. One living at home tended to have better strategies case of UPS was diagnosed, and the player in for coping with stress than those at university, question was rested for four weeks, then eased who had poorer social support and inadequate back into training. He is currently playing well.
recovery strategies. These latter players appeared to be under-recovered rather than overtrained.
coaching staff that new university students need Playing for additional teams put the athletes more support than they received last season, under physical and mental pressure. The inability particularly for improving their self-regulation, to recover properly between one match and the next led to a decline in fitness and an inability to shake off niggling injuries, while the inability to Meetings are regularly held with all players to say ‘no’ to coaches at university, school or club deal with injuries, selection issues and other led to an increase in stress, which has been shown problems, an approach which has been shown to be useful in alleviating stress(34). In the previous While the Rest-Q did not highlight the causes season, players who got injured did not always of inadequate performance, it did pick out continue their rehabilitation, or stopped players who had poor recovery routines and attending training sessions for five to six weeks. those who were suffering from stress. These two The coaching staff have realised that they are factors were not always concurrent, reinforcing as important as physiotherapists to injured the view that they are different parts of a process players and now play a more active role in leading to underperformance(33). This enabled the coach to have more in-depth conversations with the players and to a greater understanding of the aware of the importance of recovery and the risks motivation and habits of each player.
of the stress some of the players face, it is our However, the use of the Rest-Q at intervals of hope that the incidence of underperformance and six to eight weeks did sometimes lead to players being overlooked when symptoms ofoverreaching appeared between tests, while the James Marshall
be more important than what is actually true.
Stone et al(7) gave black and white students a laboratory golf task that ostensibly measured Stereotype threat: an
‘natural athletic ability’, ‘sport intelligence’, or ‘sport psychology’, depending on how the test was alternative explanation presented. Nothing changed in the test itself, just change. London:
the perception of what the test measured. Both for the East African
black and white students scored equally well on dominance of
the sport psychology control condition. However, black participants outperformed white ones when distance running
the task was framed as a test of natural athletic ability, whereas white participants outperformed The following original paper from Canada, black ones when the task was framed as a test of published recently in the British Journal of sport intelligence. This phenomenon is referred Sports Medicine, is reproduced in full by kind to as stereotype threat and may be of help in permission of the BMJ Publishing Group. Br J explaining the dominance of certain sports by specific groups. Although scientific inquiry into Researchers have long speculated on the factors genetic differences between races remains that contribute to making an elite athlete. When unresolved, previous research suggests that belief a particular group appears to dominate a given in such differences has a large impact on domain, even more speculation and interest is generated. Current examples from sport include Steele and Aronson(8) introduced stereotype the American dominance of basketball and the threat as an explanation for the lower scores of Northern European dominance of Nordic skiing.
An example that has garnered much attention(1,2) is East African dominance of middle- and long- perplexed by the persistent gap in scores between distance running. Although several empirically blacks and whites, which endured even if black based positions have been advanced to explain students came from well educated families of the interindividual variation in performance(3,4), middle-class standing. However, Steele and the dominance of black athletes in certain sports Aronson found that black students scored just as has been commonly attributed to factors such as well as whites on standard intelligence tests when social Darwinism – that is, the hardships of the tests were presented as diagnostic tools that slavery resulted in a degree of genetic selection(5) did not measure intellectual capacities. They – and environmental determinism – that is, determined that it was not the test itself, rather physiological adaptations associated with living the situational pressure surrounding the test, that under certain environmental conditions (1).
resulted in poorer scores. Performance decreased Hamilton (6) examined empirical evidence for a when black students were confronted with the range of influences that may contribute to East possibility of confirming a widespread stereotype environmental, social, psychological, and Significantly, stereotype threat affects the physiological variables. After examining research academic vanguard more than it does the weaker from various disciplines, he concluded that there students. A person has to care about a domain in was no clear explanation for the East African order to be disturbed by the prospect of being stereotyped in it. Good students are generally psychological factors may perpetuate this invested in and have identified with the domain dominance by attributing differences between and thus are more prone to the situational African and white running performances to pressure that is stereotype threat. Students who stable external factors, thereby disempowering did not identify with the domain were remarkably white runners and empowering East African unaffected. Weaker students reduced cognitive runners. Regardless of the possible existence of effort as soon as the test became challenging, physiological advantages in East African runners, resulting in poor performance, regardless of belief that such differences exist creates a whether they were under stereotype threat or not(9). Therein lies another key to stereotype threat significant consequences on performance.
– the test must be challenging. It is only when one gets to a difficult section, and the possibility arises Stereotype threat
of confirming the negative stereotype, that Recent research in psychology has unveiled sufficient stress arises to impair performance.
insights that are particularly relevant to this Oddly enough, a person does not even have to debate. It is distinctly possible that what we believe the stereotype to be affected by it.
believe to be true about our genetic make-up may Awareness, even at a subconscious level, appears to be sufficient. For example, Levy (10) primed [senior citizens] using subliminal messages and then gave them a memory test. Those who had Short-term effects
been primed with negative words associated with old age, such as senile or forgetful, performed stereotype threat has been attributed to the worse than seniors primed with positive words anxiety and distress caused by association with a negative stereotype. Blascovich et al(16) examined Spencer et al (11) found that stereotype threat the effects of stereotype threat on blood pressure was equally applicable to women and maths in African Americans. They found that groups skills. If women are reminded of the stereotype placed under stereotype threat displayed larger that they are inferior to men in mathematical increases in mean arterial blood pressure (a ability, their test scores decrease. If the same test measure of somatic anxiety) and performed more is reframed so that women believe it is simply a poorly on difficult test items than African research tool, they score just as well as men.
Americans not under stereotype threat. In typical Current findings indicate that anywhere a models of anxiety(17), the occurrence of a stressor, stereotype exists, stereotype threat can be in this case stereotype threat, creates a state of invoked and performance depressed. In a related anxiety (see figure 1, below). State anxiety(18) is study, white men, selected on the basis of their manifested either somatically through physical strong maths skills, performed worse when they responses, such as sweating and increased respiration, or cognitively through worry or traditionally thought to excel at maths. A control group not subjected to stereotype threat suffered manifestations has been linked to negative effects on physical performance(19). Further, whereas a The sporting field also contains its share of certain amount of physical arousal has been seen stereotypes, particularly when it comes to black- as beneficial for sport performance (cf the white differences. The perception of the athletic inverted U hypothesis)(20), certain research(21) superiority of black people is widespread, with the suggests that any amount of cognitive anxiety is media contributing substantially to such thinking . Stone et al(13) examined popular perceptions of Moreover, athletes performing at elite levels of racial stereotypes by having participants evaluate competition normally adopt a telic, or serious, the abilities of a male basketball player based on goal-oriented motivational state. To the elite a radio broadcast of a college game. Even though athlete, performing well is an important outcome.
participants listened to the same broadcast, they However, researchers(22,23) suggest that adopting a were more likely to attribute talent and natural motivational state that is telic is more highly athletic ability to the player if they thought he was affected by anxiety than adopting a paratelic – black and were more likely to attribute hard work that is, playful, non-serious – motivational state.
and sport intelligence to the player if they Long-term effects
This widespread societal belief in the athletic Perhaps the most damaging effects of stereotype superiority of blacks is actually a relatively recent threat are long-term, such as feelings of phenomenon. Hoberman (14) notes that during dissatisfaction and ultimately dropout from sport.
colonial rule blacks were considered inferior The benefits of long-term involvement in physical sportsmen. In fact, at the dawn of the 20th activity are well known. They include increases in century there was concern even among black physical competence and associated increases in scholars at the lack of physicality of the black race(14). However, the tables have turned Figure 1 proposed model of stereotype
considerably in the past hundred years.
threat effects on sport performance
Impressive accomplishments from black athletes during the first decade of the 1900s – for example, Marshall Taylor and Jack Johnson – followed by the record-breaking performances of black sprinters like Jesse Owens provided the basis for the belief that black athletic superiority is genetic in origin(15). The current dominance of black athletes in a number of high-profile sports has certainly done nothing to dispel this belief.
Furthermore, as Hamilton suggests(6), thepsychological edge this belief gives black athletesmay be the key to maintaining that superiority.
Indeed, in stereotype threat we see evidence of self-esteem(24). However, Steele(25) postulated that, ways of dealing with situations involving in chronic situations of stereotype threat, stereotype threat. Steele(25) presented methods individuals become pressured to ‘disidentify’ with for overcoming stereotype threat in academic the domain to preserve feelings of self-worth.
settings, several of which are also useful for Disidentification involves a reconceptualisation performance in the athletic environment. Steele(9) of one’s self-image to remove the value associated theorised that underperformance appeared to be with a domain, thereby reducing the impact of rooted less in self doubt than in social mistrust.
Therefore niceness and reassurance on the part replicated these results in a sport context.
of the teachers was not enough. Steele found that emphasising high standards was the key to maintaining self-image, can undermine the gaining social trust. For criticism to be accepted motivation required for long-term involvement in across the racial divide in an academic setting, an activity. Sustained motivation is dependent on feedback had to be given with the emphasis on feelings of achievement and accomplishment(27).
high standards, conveyed with the belief that the In a related study, Stone(26) found that stereotype student could achieve those standards.
threat was related to the quality of practice Although this research has yet to be replicated performed by participants executing a golf task.
in an athletic domain, it provides clear guidance Specifically, white athletes who felt they were for coaches working in multiracial environments.
being examined for natural athletic ability When dealing with athletes, coaches should showed less practice effort than white athletes who were not under the threat of confirming performance for all, irrespective of race. Evidence racially based stereotypes – that is, poor white suggests in order for stereotype threat to athleticism. In addition, stereotype threat only influence performance, the stereotype must be important component of their self concept.
Accordingly, coaches should avoid off-hand Participants who were disconnected from the comments or jokes suggesting, for example, ‘white outcome of the task performed at a level no men can’t jump’ or ‘blacks are better runners’, especially before competition. In addition, hypothesised that athletes concerned with coaches and trainers should show clear optimism confirming a racially based stereotype ‘self- in their athlete’s abilities. All attempts should be handicap’ – that is, perform less effortful practice made to increase the athlete’s feelings of self- – to create ambiguity about the cause of a poor efficacy – that is, the athletes’ beliefs in their performance. Athletes proactively respond to an abilities to accomplish desired courses of action – anticipated mediocre outcome by withdrawing before competition. Moreover, these feelings practice effort, thereby avoiding the confirmation must be reinforced after the event regardless of of a stereotype about poor natural athletic ability the results to ensure that stereotype threat has a in white athletes. Although longitudinal studies limited role in future competitions. Clearly, of the effects of these actions have not been coaches should also stress the equivocal research performed, it seems reasonable that decreased findings on race and athletic performance. One practice effort over time would undermine skill method of reducing the negative consequences associated with stereotype threat is by minimising adaptations necessary for performance at the the legitimacy of the stereotype. If athletes are highest levels of sport competition.
educated as to the lack of consistent findings forracial dominance in sport, the power of the Effects on young athletes
stereotype may be effectively limited.
The extent to which athletes choose or opt out of Research examining the role of stereotype sports based on perceived genetic suitability is an threat in elite levels of performance is virtually area worthy of future study. Just as negative non-existent. As a result, the suggestions stereotypes can lead women away from maths- presented in this paper, although based on strong based careers in finance or engineering, there is evidence to suggest that athletes may be choosing speculative. Future research should consider the their sports based on athletic stereotypes.
role of stereotype threat as a reason for Coakley(28) notes that young athletes have performance differences in racially dominated internalised these stereotypes and are choosing sports such as middle- and long-distance running.
sport participation accordingly. He speculates Without indisputable evidence indicating the that this is the reason why white running times in genetic advantages associated with a specific certain events have actually decreased over the racial group, researchers should continue to past few years; whites are opting out of some examine alternative explanations for the apparent sports based on perceived genetic inferiority.
dominance of one group over another in sport.
Coaches and support staff need to be aware of J Baker, S Horton
material is presented to a T-lymphocyte immunecell, it too proliferates; some T-lymphocytes Strategies to boost
(CD8+) become activated to kill any cells carryingthis foreign material, while others (the CD4+ T- your natural immunity cells) secrete biochemical substances (such as
interleukins and cytokines) which boost the and keep infection and activity of killer cells.
The point is that your immune system contains the effects of exercise
a large number of functionally different cells and stress at bay
a wide array of defence mechanisms. Because ofthis, it’s actually quite difficult to accurately Athletes constantly live on a knife-edge between assess the impact of nutrition on immunity, especially as there are no instruments that can programme might shed valuable seconds off your predict the cumulative effect of several small PB, but if it proves too much and you come down positive changes in different immune system with a viral infection you stand to lose fitness, not gain it. Building and maintaining immunity should be thought of as a vital part of any immunosuppression (PEIS), in which certain athlete’s programme, particularly as the existence of post-exercise immunosuppression is now well- temporarily depressed after heavy bouts of established(1,2,3). But what can athletes do to exercise, is now well-documented in athletes(5,6), maximise their immunity and reduce the risk of linked with an increased incidence of infection, particularly of the upper respiratory tract. In particular, it appears that during recovery from complex array of different elements, whose job is prolonged, intense exercise the number of to work synergistically to recognise, attack and lymphocytes in the blood is reduced below destroy foreign invaders. In very simple terms, resting levels and the function of natural killer impaired’
there are two lines of defence. The first is the and B cells is impaired(7,8). Strenuous exercise also innate immune system, consisting of barriers seems to inhibit innate immunity by reducing designed to prevent foreign agents from infecting mucosal protection(9). And there is evidence that this drop in immunity may worsen the disease ● physical barriers, such as the skin and epithelial outcome when exercise is performed during the tissues of the lungs, nose and intestinal tract; incubation period of an infection(10). The ● chemical barriers, such as the high acidity of consensus of scientific opinion is that PEIS occurs mainly as a consequence of the increased ● cellular barriers, such as phagocytic cells whose secretion of stress hormones, such as adrenaline and cortisol, during vigorous and prolonged If the first line of defence is breached, an exercise, particularly as these types of hormones infection occurs and then the ‘acquired’ immune system kicks in to fight the infection and destroy it.
The acquired system employs a number of The role of glutamine
different cell types working in cooperation to help In recent years, the role of an amino acid called the body recognise and defeat the invaders. For glutamine has come under intense scrutiny.
Several studies have demonstrated a fall in macrophages ingest any foreign material and then plasma glutamine levels following vigorous present it to other cells known as lymphocytes.
exercise, and doctors had long been aware that When this material is presented to a B-lymphocyte this also occurs as a consequence of other immune cell, the lymphocyte is signalled to stressful events, such as trauma and burns, which proliferate and produce antibodies that will specifically bind to the foreign invader. These subsequently shown that many immune cells have antibodies attach themselves to the surface of the an unusually high capacity to utilise glutamine(11) invader (usually bacteria or a virus-infected cell) and that (unlike most cells in the body) these and act as ‘labels’, effectively telling the other cells immune cells were unable to synthesise glutamine of the immune system that these invaders are in situ and therefore required a constant supply foreign and need to be destroyed. This destruction from blood plasma(12), glutamine depletion was can be by means of macrophages engulfing the considered by many to be an obvious trigger for invader, by an attack from other immune cells known as ‘natural killer cells’, or by immune exhaustive exercise. This theory was supported by proteins collectively called ‘complement’, which in-vitro studies showing that glutamine stimulates can punch holes in the bacterial wall. If the foreign the activity of certain immune cells, such as lymphokine-activated killer cells(13).
their carbohydrate intake to ameliorate PEIS. Given these findings, scientists quickly began Studies have shown that when athletes train in to speculate that PEIS might be prevented if a glycogen-depleted state after spending several extra glutamine could be administered after days on low-carbohydrate diets (less than 10% of exercise – hence the proliferation of glutamine dietary intake from carbohydrate), the release of supplements. However, more recent research has stress hormones, such as adrenaline and cortisol, thrown this idea into doubt. While a study on is exaggerated by comparison with normal or high-carbohydrate dietary conditions(19,20).
found they experienced only half the rate of Moreover, this enhanced stress hormone release respiratory tract infections of unsupplemented is linked to a decrease in immune function; for controls(14), the same scientists also found that example, just one hour’s exercise at 75% VO2max that glutamine supplementation after a marathon in a glycogen-depleted state resulted in a did not influence the lymphocyte distribution or significantly bigger fall in circulating immune the concentration of other immune proteins.
lymphocytes than the same amount of exercise on Meanwhile, glutamine-supplemented cyclists a high-carb diet(21). The good news for athletes is who performed 60, 45, and 30 minutes of exercise not just that high-carbohydrate diets can reduce the stress hormone response but also that taking separated by two-hour rest periods, showed no in carbs during exercise reduces stress hormone increase in immune activity by comparison with production which, in turn, seems to ameliorate In a landmark study carried out last year, concentration did not prevent post-exercise immunodepression, a finding which has since carbohydrates during 2.5 hours of strenuous been confirmed by a further study on glutamine- cycling(22). Taking in 30-60g of carbohydrate per supplemented marathon runners(16). Scientists hour in the form of a 6% carbohydrate drink was now believe this is because the post-exercise drop found to prevent the decrease in an important in plasma glutamine is relatively small, to around type of immune cell, known as interferon-g- 80-90% of resting values, by comparison with the positive T-lymphocytes, experienced by a placebo drop in severe burns patients, whose glutamine control group. The researchers also discovered levels can fall to below 40% of normal. Although ‘There is
there is a reduction in circulating glutamine after showed no measurable drop in production of an exercise, there still seems to be enough of the active chemical (known as interferon-g) that stuff for the immune cells to function normally.
these T-cells secrete when stimulated. Interferon- g production is critical to anti-viral defence, and undoubtedly fall, there is evidence that the intra- scientists now believe that suppressed production cellular levels of glutamine in important immune after strenuous exercise may be an important cells in the blood actually rise(17). Glutamine, it factor in the increased risk of infection.
seems, is not the magic immune bullet that These results are supported by another recent study from the US, where two groups of runners were asked to perform a three-hour treadmill run The carbohydrate connection
at 70% VO2max, one ingesting a carbohydrate In recent months, carbohydrate-bashing has drink and the other a placebo(23). By comparison become more fashionable than ever, and it seems like everyone and his dog is now flourishing on a low-carbohydrate diet! But, quite apart from the concentrations of a number of cytokines – very weight-loss myths pedalled in the press, athletes small protein molecules secreted by cells of the would seem to have even more reason to ignore immune system, which regulate the intensity and this fashion than most because there is strong duration of the immune response. The lower evidence that intense training coupled with a low- levels of cytokines measured in the carbohydrate- immunosuppression! The PEIS observed after ‘immune stress’. However, it remains to be intense training appears to occur mainly as a established whether carbohydrate ingestion result of the secretion of stress hormones into the during training and competition can reduce the body, and scientists have proposed that any incidence of upper respiratory tract infection nutritional manipulation capable of reducing this (URTI). The American researchers mentioned stress hormone release should limit this immune above have noted a beneficial trend in a study of suppression(18). The latest research suggests not 98 marathon runners, but their results did not only that limiting carbohydrate intake induces a reach statistical significance, indicating the need greater release of stress hormones during exercise, but also that athletes can manipulate The role of essential vitamins and minerals in maintaining immunity has long been recognised; in the laboratory echinacea does demonstrate a deficiencies of the any of the vitamins A, E, folic significant effect on a number of immune cells, acid, B6, B12 and C can impair immunity, as can especially on macrophage activity(30), as well as on deficiencies of the minerals iron, copper, the activation of some leucocytes and natural selenium, zinc, magnesium and manganese(25).
killer cells(31). But how, if at all, does this translate But are there any nutrients that can offer extra immune support when taken in higher quantities than their current UK Reference Nutrient Intake disappointing. While some small-scale studies (RNI) values? The obvious candidate is vitamin have indicated that, in those already infected, the C; ever since Dr Linus Pauling carried out his severity and duration of acute URTIs may be original studies into vitamin C, the notion that it modestly reduced with echinacea, three recent might be beneficial for combating URTIs, such as double-blind placebo-controlled studies found no the common cold, has become widely accepted.
evidence of immunostimulation(32,33,34). problem with echinacea studies is that many leucocytes and has also been implicated in a commercially available echinacea products do not possess enough active constituents to exert a promotion of T-cell proliferation and inhibition definitive clinical effect. To get around this of virus replication, the research on athletes and problem, a very recent double-blind, placebo- immunity has produced very mixed results.
controlled study used a formulation prepared Two studies carried out in the 1990s initially from freshly harvested echinacea plants, which provided strong support for a protective effect of contained the suspected active constituents high doses of vitamin C in athletes. In the first (alkamides, cichoric acid, and polysaccharides) at study, two groups of ultra-marathon runners known and high concentrations(35). A group of 282 were supplemented for three weeks leading up to healthy adults with a history of two or more colds a 90k race, one group taking 600mgs of vitamin C in the previous year were randomised to be per day (15 times the current RNI of 40mgs) and treated with either echinacea or placebo at the the other taking placebo(26). In the fortnight after first onset of cold symptoms. During the study period, 128 subjects contracted a common cold (59 on echinacea and 69 on placebo). But the controls. A follow-up study carried out three echinacea group reported less troublesome years later supported these results(27); ultra- symptoms and responded faster to ‘treatment’ marathon runners were split into four groups, than the controls. The researchers concluded one given 500mgs per day of vitamin C, the that their results pointed to the need for more, second receiving the same plus 270mgs of vitamin larger scale studies using standardised extracts. E, the third 300mgs of vitamin C, 200mgs of vitamin E and 18mgs of beta-carotene, and the A role for probiotics
fourth receiving just placebo. After the 90k race, It was almost a century ago that the Nobel prize the runners receiving the highest doses of vitamin winner Elie Metchnikoff carried out his research into fermented milk products, such as live regardless of whether they were also receiving yoghurt, and suggested that, far from being the antioxidant nutrients (vitamin E and beta- inevitably detrimental to health, bacteria could carotene), clearly pointing to vitamin C as the play an important role in maintaining it. Since then, a wealth of research has accumulated, The problem is that other studies have not confirming that certain types of bacteria are been able to replicate these findings. For beneficial to human health when ingested. These example, no immunity benefits were found in an so-called probiotics can be defined as ‘live microbial feed supplements, which beneficially supplemented with 1,000mgs of vitamin C per affect the host by improving its intestinal day for eight days before completing a 2.5-hour microbial balance’. Although probiotics have run(28). And in a very recent placebo-controlled gastrointestinal health benefits, they’ve never 1,500mgs of vitamin taken daily for seven days been perceived as ‘sexy’ by the athletic before and during an ultra-marathon did not community. But that might be about to change! positively affect any aspect of immune function. A number of herbs are reputed to stimulate immunity, but in recent years it is echinacea immunostimulatory properties of probiotics – purpurea that has become particularly popular and the results are impressive. A recent meta- among athletes, despite a lack of evidence of its analysis of relevant studies examined the effectiveness against PEIS. There’s no doubt that scientific literature on probiotics and immunity in -vitro, in animals and in humans(36). Of these, 48 reported positive immunostimulatory effects, 17 ● Vitamin C – The evidence is too mixed for a firm
in-vitro, 21 in animals and 10 in humans. To date, recommendation but, given its low toxicity and there are no published studies on the possible cost, athletes wishing to take a modest supplement benefits of probiotics for athletes, but things are (200-1,000mgs per day) have little to lose; moving quickly and two studies on this very topic ● Glutamine – Although beneficial in the clinical
are due for publication later this spring. In the setting, there’s little hard evidence that it offers screened for levels of an immune protein called ● Echinacea – Athletes who contract a URTI may
secretory immunoglobulin A (sIgA), with 52 find that taking a standardised echinacea found to have below-average levels(37). These 52 preparation shortens its duration. However, were then split into three groups for four weeks, while echinacea does not appear on the IOC’s the first treated with a probiotic food supplement banned substances list for 2004, those subject to containing a proprietary blend of beneficial drug-testing should be aware that all herbs bacteria (Lactobact omni FOS, manufactured by Winclove Bio Industries), the second a zinc and ingredients which, under certain circumstances, may inadvertently produce a positive result; together. When their faeces were analysed, only ● Probiotics – Although the early indications are
those taking the probiotic were found to have promising, very little data exists on the benefits of significantly increased levels of sIgA.
probiotics for athletes. Foods like live yoghurt and other fermented products can be included in Germany, examined the effects of probiotics on the diet if desired, especially as they are also rich post-exercise immunosuppression(38). A total of 44 endurance athletes were split into two groups, recommended after antibiotic treatment. To date one to receive probiotics, the others to act as there’s insufficient evidence of the benefits of controls. After four weeks of supplementation supplementing the diet with probiotics, although with a probiotic blend (Lactobact omni FOS), the athletes were tested after a 60-minute endurance ● Lifestyle – Athletes should ensure they get
session. As expected, faecal microflora was plenty of sleep and relaxation, minimising fatigue and emotional stress where possible. Good researchers also discovered that this group hygiene is also important, with regular hand experienced a lesser post-exercise decrease in the washing recommended to reduce the risk of level of circulating natural immune killer (NK) transferring virus particles to the mucous cells than the controls, with a faster return to pre- membranes of the eyes, nose and throat.
exercise NK cell levels – an indication that Andrew Hamilton
probiotics may be able to reduce PEIS. As with all unpublished studies, these results should be interpreted with caution, but if they are confirmed the role of probiotics in the health of athletes wishing to maintain maximum immunity: Promoting sport and exercise to adults may be ● Carbohydrate intake – The normal diet should
an expensive waste of time. People are most likely to be active – and remain active – as adults accounting for 60% or more of total calories.
if they have enjoyed sport and exercise in Low-carb diets such as Atkins or Zone should be childhood and adolescence. That’s the clear avoided. For longer (90-plus minutes) or very implication of a pair of recent studies examining intense sessions, 500-1,000mls of carbohydrate factors associated with adherence to exercise in drink containing 60g of carbohydrate per litre The first of these, carried out in Israel, ● Diet quality – Immunity can be adversely
involved 3,818 Jewish men from a variety of affected by any number of nutrient deficiencies.
industrial settings who participated in the Athletes should ensure that their diet is rich in Cardiovascular Occupational Risk Factors in whole unprocessed foods, fruits and vegetables, Israel Study (CORDIS) in 1985-87. Information contains adequate high-quality sources of protein on leisure time physical activity (LTPA) was and is low in fatty, sugary, fast or processed food.
obtained from a number of questions in the questionnaire and those currently taking part in supplement may be beneficial in preventing a LTPA on a regular basis – ie at least once a week nutrient shortfall, but large doses of any single for half an hour – were grouped together.
nutrient should be avoided as this could create participants across a range of demographic and participation in young adults under 30, and the occupational variables, participation in organised school-age sporting activities emerged as a strong predictor of adult physical activity, reported by two-thirds of active adults compared with less Factors thought to be associated with exercise than one-third of inactive ones. This strong were analysed in relation to the amount of association remained when a more rigorous definition of adult activity (half an hour for five onwards. Analysis of the data showed that adulthood exercise was predicted by just two ‘Our findings, in a cohort of predominantly middle-aged industrial workers, are consistent competitive sports in adolescence. Education, with other work showing that organised sporting marital status, number of children, number of activity as a child and adolescent predicts LTPA as both a younger and older adult,’ comment the diseases, smoking, alcohol use, and leisure time researchers. ‘Participation in organised after- activities other than exercise and sport were not school sports may provide youth with a skill set associated with adulthood exercise level.
and enjoyment of sport that help form the foundation for activity habits later in life… Efforts researchers, ‘that early childhood environmental that lead to increasing levels of childhood factors strongly influence exercise level physical activity may lead to a more physically throughout the lifespan. Therefore, interventions In the second study, from Finland, researchers participation may achieve more beneficial long- studied 117 sets of identical male twins aged term results by targeting families and other childhood and adolescent environments.’ enhanced adherence to exercise in adulthood.
Med Sci Sports Exerc, vol 35, no 12, pp2038- Exercise in childhood and adolescence and participation in competitive sports had been shown in earlier studies to predict exercise Please call (UK) 020 7251 3258 or (Australia) (02) 8243 5767 if you have a problem with your subscription A 6-issue subscription to Peak Performance, the world’s only sports research newsletter, costs just £28-85. A 12-issue subscription costs £57-75 (Europe, £62-75, USA US$99, the rest of If you would like us to send a free copy of Peak Performance to an interested friend, please write to us with their name and address: Peak Performance, 67-71 Goswell Road, London, EC1V 7EP. Alternatively you can phone us with their details on 020 7251 3258.
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OBSTETRICS, GYNAECOLOGY & UROLOGY Guidelines on the management of erectile dysfunction • British Society for Sexual Medicine • Epidemiology and risk factors – other urological symptoms (past or present)• Erectile dysfunction (ED) has been defined as the persistent inability to attain and/or maintain an • A digital rectal examination (DRE) of the erection sufficient fo