The athlete at high Roy J. Shephard, m.d., ph.d., Toronto

Summary: Track times at moderate logical studies concerned with balloon- mg. tablet four times daily) reduce im- (7000 to 8000 feet) are ists, mining operations, mountaineering mediate symptoms; they act mainly by modified by decreased wind resistance and aviation from the more subtle prob¬ counteracting the excessive washout of and by systemic disturbances such lems of the large South American cities. carbon dioxide from the body, thereby as mountain sickness, disruption of At 22,000 feet there is no question permitting more adequate ventilation training, and a decrease of maximum that a man is short of , and un- and cerebral blood flow. Acetazolamide oxygen intake. The optimum period of less he is acclimatized, the duration of also has some diuretic effect; this is acclimatization is probably two to three useful consciousness will be no more not great enough to account for its days. This permits adjustment of than perhaps 10 minutes. But in Mexico therapeutic value, but may be a dis- cerebrospinal fluid acid-base balance, but City, at 7350 feet, effects are typically advantage when treating athletes, since minimizes disturbances of plasma slight and easily confused with , in any event there is difficulty in main- volume and volume. Further pre-contest anxiety and gastroenteritis. taining plasma volumes during the first study is needed to establish whether few weeks at high altitudes. altitude training can improve Air resistance performance in sea-level competitions. Oxygen debt Most athletes except swimmers get a Resume: L'athldte et les hautes altitudes small boost to their performance at In very short events the rate of build- Les performances d'un athlete higher altitudes because of the dimin- up of oxygen debt, the so-called anaero- s'entrainant a des altitudes moyennes ished air resistance. At sea level 11 % of bic power, is the main physiological de- (7000 a 8000 pieds) sont modifiees par the energy needed to run three miles terminant of performance; the race is une moindre resistance au vent et par is attributable to wind resistance, and concluded before the athlete has devel¬ des troubles generaux comme le mai in Mexico City this is cut to 8%J Com- oped the maximum tolerable oxygen de montagne, un dereglement de petitors in long-distance events thus debt. I'entrainement physique et de gain a bonus of about 3% and in short- In medium-distance events such as I'oxygenation maximum. La periode distance and throwing events the gain 400 and 800 metre track contests, some d'adaptation optimale est probablement is somewhat larger. 50% of energy expenditure may be de deux a trois jours. Elle permet de derived from the build-up of a large retablir I'equilibre acide-base du LCR, Mountain sickness oxygen debt. Acute altitude exposure mais minimise les troubles de la does not alter the maximum oxygen volemie et du debit systolique. II faudra Barcroft2 gives a vivid account of the debt, but as the athlete becomes ac¬ de nouvelles etudes pour savoir si mountain sickness that developed during climatized he loses bicarbonate from I'entrainement d'athletes en altitude his railway journey across the Andes. the blood and tissues, and the maxi¬ pourrait ameliorer leurs performances Nonspecific but very unpleasant symp¬ mum tolerated lactate level diminishes.5'6 lorsqu'ils entrent en competition au toms included headache, insomnia, ir- On the other hand, lactate formation niveau de la mer. ritability, and a variety of gastroin¬ in sub-maximum exercise is increased. testinal disturbances. Despite some This has several practical implications alarming reports from coaches, the al¬ for the training program: Is the question of athletic performance titude of Mexico seems City insufficient 1. The athlete must learn to move at at high altitudes a dated concern now to cause sickness in the person that the Mexico have been healthy a slower pace if a distressing Olympics who undertakes no more than moderate is not to safely completed? the an- recreational a hyperventilation develop Surprisingly, activity. Indeed, colleague in a race. swer is no. Cities at even greater alti¬ and I carried out maximum effort prematurely daily 2. Since limb movements are syn- tudes continue to vie for international tests during our first week in Mexico contests, and the raised in chronized with breathing, a new problems City and yet noticed no symptoms. must also be 1968 the optimum period of ac¬ The international be respiratory pattern climatization and the risks of competitor may learned. pulmonary more vulnerable since, if he is to keep 3. 85 edema and in he must Recovery following repeated training, sustain several to 90% speed sprints is slower remain current issues. Further, high- hours of vigorous exercise per day.3 altitude are now serious- than normal, so that rest pauses training camps Cerebral symptoms such as headache should be and the total ly advocated, and the problem is be- are due to an increase of extravascular lengthened of not volume of training may need to coming increasing importance fluid. There is no alteration in gastric be reduced. only to specialist team physicians, but secretion or but alterations in also to motility4 ordinary medical practitioners the volume and composition of pancrea- Some athletes reported residual mus- as the citizens of Toronto and Montreal tic juice may contribute to the gastro¬ cle stiffness for 24 hours after practice increasingly take active holidays at intestinal disturbance. sessions in Mexico City.7 Lactate does mountain ski resorts. Although chronic forms of moun¬ not persist for more than half an tain sickness have been described, in hour, even at high altitudes, and an Limitations to existing knowledge most competitors the symptoms resolve increased exudation of fluid into the within 48 hours. Treatment is therefore tissues be for these In may responsible reviewing existing knowledge, it is conservative, with a temporary lighten- residual symptoms. necessary to distinguish early physio- ing of training, symptomatic therapy Reprint requests to: Dr. Roy J. Shephard, for headache and general encourage- Oxygen transport Dept. of Environmental Health, ment. Carbonic inhibitors School of Hygiene, University of Toronto, anhydrase Toronto, Ont. such as acetazolamide (given as a 250 The main physiological determinant C.M.A. JOURNAL/AUGUST 4, 1973/VOL. 109 207 of events lasting from one to 60 minutes parently healthy skiers at altitudes of athlete nor his team may be able to is the maximum oxygen intake, the no more than 3-4000 metres. If rec- afford the costs of a prolonged sojourn ability of the heart and lungs to pump ognized and treated by bed rest, oxygen at high altitude. Further, the time re- oxygen from the atmosphere to the and antibiotics, resolution usually oc- quired for physiological acclimatization working tissues. curs within two to three days. No evid¬ must be neatly balanced against ad¬ Many measurements of maximum ence of pulmonary edema was found verse effects of the unusual environ- oxygen intake were made at moderate in the endurance competitors in Mexico ment . boredom, reduction of train¬ altitudes during 1967 and 1968. One City. ing, discouragement from poor track attempt at data synthesis8 concluded times, and infection by unfamiliar that there was a 3.2% loss of maxi¬ Track performance microorganisms. mum oxygen intake for each 1000 feet of altitude in excess of 5000 feet. A Predictions of track performance Acid-base balance second review9 suggested that unac- prior to the Mexico City games were climatized persons suffer a loss of 7% commonly based on the comparison of On first arrival at high altitude, the for each 1000 metres above sea level. the 1955 Pan-American games results body attempts to compensate for the The two interpretations are equivalent with those of previous and subsequent low oxygen pressure by an increase of to 7 and 16% loss of endurance in Pan-American competitions.a2'13 Such ventilation, measured at body tem- Mexico City. The author believes the analyses showed a small gain in track perature and pressure. However, this lower figure is the true physiological performance over distances of 100 to leads to an excessive washout of C02 decrement, and that the larger loss is 400 metres, and a deterioration of times fiom the body. The normal stimulus attributable to extraneous factors such for more protracted track and swim- to ventilation is lost and intermittent as disruption of training, gastrointesti¬ ming events, amounting to 6 to 7% breathing may occur, especially at nal infections and simple fear of alti¬ in 5000 and 10,000 metre contests and night. The systemic blood pressure is tude. 17 to 22% in the 42,000 metre con¬ raised, increasing the work of the heart, test. In a few instances it was possible and the cerebral blood flow is reduced, Cardiac and respiratory pathology to compare the performance of the increasing the liability to signs of same individual at high altitude and cerebral at the end of a race. How real are the fears of myocardial at sea level. The apparent effect of Adaptive changes in the bicarbonate infarction and pulmonary edema? My high altitude naturally varied with the content of the cerebrospinal fluid occur cautiously worded warning of 196810 duration of acclimatization (often one in a few hours and these are sufficient was seized by the popular press, and to three days), the intensity of com- to permit a more normal pattern of banner headlines screamed "Doctor petition, and other unrelated problems breathing, with gains of arterial oxy¬ says athletes will die in Mexico City". such as gastroenteritis. Nevertheless, gen saturation both at rest and in ex¬ I neither nor expected suggested such the immediate loss of performance was ercise.15 Changes in the buffering ca¬ an outcome. However, maximum exer¬ rarely more than 6 to 8%, even in pacity of the blood also occur, but more cise does bring any heart close to endurance events. When permanent slowly, over a week or more. Resolu¬ anoxia. Let us look at the electrocardio- high altitude residents competed at sea tion of mountain sickness is probably gram of a young man engaged in level, the gain of performance was even related mainly to a restoration of the maximum effort at sea level. Follow¬ smaller (2 to 4%). pH of cerebrospinal fluid and arterial ing maximum effort, the normal large Performance at the Olympic Games blood. On the other hand, the tolerance upright T waves are flattened to the was rather better than predicted by of anaerobic exercise diminishes as the point where they virtually disappear. such analyses.9-14 Normally, the win- bicarbonate is excreted. The older athlete with some degree of ning performance in the Olympic atherosclerosis may show a frank de- Games averages 2.9% poorer than cur- pression of the ST segment at this rent world records, yet in Mexico City stage. 29% of competitors actually exceeded An increase in the hemoglobin con¬ If an endurance event is performed the best world marks and the average tent of the blood is a second important at the same rate at a high altitude, of winning scores was only 0.9% be- long-term adaptation to increased al¬ myocardial anoxia will inevitably be low world records. In order to separate titude. The expectation in Mexico City greater than in a sea-level contest. At short-term events (helped by the di- was that the oxygen content of arterial the same time, pulmonary and systemic minished wind resistance) from long- blood would be reduced by 7%. In vasoconstriction will increase the work term events, Craig suggested that all sub-maximum effort compensation is of the heart, and irritability of the data should be expressed as a per- possible through a 7% increase of myocardium will be increased by an centage of world records and plotted heart rate, but in maximum effort enhanced secretion of catecholamines. against their duration. When a linear there is likely to be a proportionate No coronary episodes occurred in regression was fitted to track and swim- reduction of maximum oxygen intake. Mexico City, but Pugh1 reported dys- ming results, it become clear that while Obviously compensation would be rhythmia in two of six British runners. world records were exceeded in brief possible with a 7% increase in the Following an endurance event, mani- events, there was a progressive de¬ blood hemoglobin level. Ultimately the festations of cerebral oxygen lack such terioration in contests lasting more changes in Mexico City were some- as central negative scotoma, loss of than one minute, ranging from 3% what greater than this, namely a 20% colour vision and incoordination are at four minutes to 8% at one hour. increase of both red cell count and also more common at high altitudes Certain outstanding performers (Keino, hemoglobin level. However, the than at sea changes level.10 Burton and Hohne) placed well to the developed relatively slowly, over a The threshold altitude for pulmonary right of the regression line. month or more.16 There may also be edema is lowest in cold climates, rang- an alteration in the oxygen affinity ing from 8500 to 12,000 feet.11 The The course of acclimatization of the hemoglobin, due either to al- majority of cases to date have been in terations in the acid/base status of miners and in Indian soldiers fighting The optimum period of altitude ac¬ the blood or to an increase in the in the Himalayas. Occasional fatal at- climatization is a vital problem for diphosphoglycerate concentration in the tacks have occurred in young and ap- every coach and trainer. Neither the red cell membrane. 208 C.M.A. JOURNAL/AUGUST 4, 1973/VOL. 109 The main help that the team physi- ment of cerebrospinal fluid acid-base ing and if so, the optimum schedule of cian can give the short-term visitor to balance. At the same time, the worst exposure to the low oxygen mixtures. a high altitude is to ensure that the effects of mountain sickness have sea-level hemoglobin value is satis- passed, and unwelcome decreases in References factory. Some athletes tend to be blood buffers and the stroke volume 1. PUGH LG: Athletes at altitude. J Physiol anemic, possibly owing to fad diets of the heart are still minimal. (Lond) 192: 619, 1967 compounded by iron loss in the sweat 2. BACROFTr J: The respiratory function of the blood. Cambridge, University Press, and increased breakdown of erythro- Altitude training 1914 cytes in the circulation. Iron 3. JOKL E: The effect of altitude on athletic therapy performance, in International Research in is helpful in those cases that show a Finally, a word on altitude training Sport and Physical Education, edited by JOKL E and SIMON E, Springfield, Ill, low serum iron. camps. Since the athlete ultimately CC Thomas, 1964, p 861 adapts well to moderate altitudes, and 4. HARTIALA K: Digestive functions in altitude conditions, in The effects of alttitude on Circulatory volume the permanent resident shows some athletic performance, edited by GODDARD R, Chicago, Athletic Institute, 1967, p 15 gain of performance on competing at 5. EDWARDS HT: Lactic acid in rest and work In the first few weeks at a moderate sea level, it is tempting to recommend at high altitudes. Am J Physiol 116: 867, 1936 altitude there is a diminution of plasma altitude training as a standard procedure 6. DURAND J, PAUNIER C, Dm LATTRE J, et al: volume and an for The cost of the oxygen debt at altitude, associated reduction in boosting endurance fitness. The ob- in Exercise at altitude, edited by MARGARIA cardiac stroke volume. This change is jective would be to compete at a time R, Amsterdam, Excerpta Medica, 1968, p 40 7. SHEPHARD RJ: A possible deterioration in more obvious at 10-12,000 feet than when was still present, performance of short-term Olympic events at 7-8000 feet. It but the body buffers at altitude. Can Med Assoc J 97: 1414, may reflect in part had returned to 1967 a response to hyperventilation in dry their standard sea-level values. Un- 8. BUSKIRK ER, KOLLIAS J, PIcoN-REATEQuI E, et al: Physiology and performance of track mountain air; other contributory fac- fortunately for the theorists, it is un- athletes at various altitudes in the United tors include the general disturbance of certain whether a true polycythemia can States and in Peru, in The effects of altitude on. athletic performance edited body-fluid regulation associated with develop within a few weeks at a moun- by GODDARD R, Chicago, Athletic institute, 1967, p 65 mountain sickness and possibly an tain camp. Often the increased red 9. FAULKNER JA: Maximum exercise at me- adaptive attempt to increase the oxy- cell count is due simply to hemocon- dium altitude, In Frontiers of Fitness, edited by SHEPHARD RJ, Springfield, Ill, gen capacity of unit volume of blood. centration. But even if a true poly- CC Thomas, 1971, p 360 There may be cythemia does 10. JOKL E, FaRUCHT AH, BRAUER H, et al: a deterioration of myo- occur, the benefit is tran- Interpretation of performance predictions cardial contractility, leading not only sitory. Increased erythrolysis, decreased for Tokyo Olympic Games, 1964, with ex- trapolations for Mexico City Olympic to a smaller stroke volume but also to erythrocyte production and possibly Games, 1968, in Exercise and Altitude, a diminution of maximum heart rate. an expansion of plasma volume will edited by JOKL F and JOKL P, Baltimore, University Park Press, 1968, p 35 With permanent residence, the prob- dissipate the gains of several years in 11. SINGH I, KAPILA CC, KHANNA PK, et al: High altitude pulmonary oedema. Lancet lem is ultimately corrected. Neverthe- two to three weeks. Training may also I: 229, 1965 less, over the first few weeks the dif- be less vigorous while at increased al- 12. JOKL E, JOKL P (editors): The effect of altitude on athletic performance, in ficulty is cumulative, the stroke vol- titude, and inevitably the pace of run- Exercise and Altitude. Baltimore, Univer- ume ning and sity Park Press, 1968, p 28 being poorer in the third than in the techniques of breathing 13. FAULKNER JA: Training for maximum the first week."7 Unless the athlete can that are learned are inappropriate for performance at altitude, in The effects of altitude on athletic performance, edited remain at this altitude for a very long sea-level conditions. by GODDARD R, Chicago, Athletic Institute, period, he may For these reasons the 1967, p 88 therefore be wise to practical value 14. CRAIG AB: Olympics, 1968: a post-mortem. compete before these changes develop. of altitude training is disputed. Faulk- Med Sci Sports 1: 177, 1969 15. SEVERINGHAUS JW, MITCHELL RA: The role ner14 comments that all runners native of cerebrospinal fluid In the respiratory to sea level who trained at increased acclimatization to high altitude in man, In Tissue adaptations Physiological Effects of High Altitude, altitudes showed some improvement of edited by WEIHE WH, Oxford, Pergamon Press, 1964 Tissue adaptations to altitude occur maximum oxygen intake over their 16. REYNAFARJE B: Hematologic clhanges dur- over one to two weeks. These changes period of residence. The initial loss of ing rest and physical activity in man at high altitude, in Ibid include an increase in the myoglobin aerobic power ranged from 3 to 19%, 17. VOGEL JA, HANSEN JE: Cardiovascular content of some, if not and there was a function during exercise at altitude, In all, muscles subsequent improve- The effects of altitude on athletic per- and development of a number of en- ment of from zero to 20%. Neverthe- formance, edited by GODDARD R, Chicago, Athletic Institute, 1967, p 47 zyme systems. less Faulkner admitted this small ap- 18. MACH RS: Acceleration of acclimatization parent gain could be an artefact due to work at high altitude. Progress Rep. Overall recommendations to learning of the test, rather than a US Army Contract DA-79-193-MD-2446, 1967 true improvement of performance. Mach"8 has summarized previous rec- The exceptional performance of run- ommendations on the optimum period ners like Keino suggests there may be of acclimatization; the majority of phys- some advantage from permanent high- iologists favour at least three to four altitude residence. However, the gains weeks of adaptation. It is important to of track time from short periods at stress that such recommendations apply mountain camps are more open to dis- to an altitude of 7350 feet, where there pute. Some authors find no improve- is little progressive deterioration of ment, while admitting that this could stroke volume. At altitudes of 8-10,000 be owing to a disruption of training feet an athlete might be worse at schedules. three to four weeks, and unless time, At the present time we are investigat- money and contest rules permitted a ing the possibility of using low oxygen lengthy sojourn, the wise plan would mixtures as the "poor man's" method be to compete before the loss of of simulating high-altitude residence. plasma volume was a serious problem. Unfortunately, we cannot carry a On this basis the optimum duration cylinder of the low oxygen mixture of higher altitude residence is probably with us everywhere; much further work between 48 and 72 hours. This permits will be needed to decide whether this recovery from the journey and adjust- technique has a place in athletic train- C.M.A. JOURNAL/AUGUST 4, 1973/VOL. 109 209