Environmental Effects

As an athlete passes through an athletic career, numerous things happen which bring changes in his environment. In the early stages, the most common changes involve long, tiring journeys, sometimes combined with a stay for a number of days in an unfamiliar place. Later in the athlete's career, there are more serious changes to take note of, and to prepare for. There are three environmental conditions which an athlete will have to learn how to acclimatise to, these are altitude, temperature and time change.

Altitude

At altitude, there is reduced air resistance, suggesting an advantage in activities involving speed, i.e. sprints. The force of gravity is reduced, suggesting an advantage where relative and maximum strength is critical.

Some of the immediate effects of exposure to altitude are increased breathing rate, increased heart rate, giddiness, nausea, headache, sleeplessness and decrease in VO2 max. The total effect of these adjustments is a reduction of work capacity.

The long term effects of continued exposure to altitude include are increased erythrocite volume, increased haemoglobin volume and concentration, increased blood viscosity, increased capillarisation, continued lower V02max, decreased lactic acid tolerance and reduced stroke volume.

For short term training at altitude, the various benefits associated with it can be offset by other fundamental drawbacks such as are poor facilities, strange diet, different surroundings and homesickness. Benefits must be weighed against these limitations, plus those created by time change and problems in traveling to the training venue.

On return from altitude training performances at sea level appear to peak between the 19th and 21st day and then again between 36 days and 48 days performance improves.

Data collected from a variety of elite endurance athletes from a variety of sports have shown that training at altitudes between 1.8km and 3km promotes improvement in endurance based activities made at sea level. At these altitudes, it can take an athlete up to three weeks to acclimatise.

High altitude may result in a drop of your VO2max. The magnitude of this decline is approx. 5 to 7% per 1000 metres [ Aviat Space Environ Med 69:793-801, 1998]. To overcome this effect a "live high train low" model was developed where athletes slept at an altitude of 2500 metres but trained at sea level. [Med Sci Sport Exerc 23:S25,1991].

Hazards of altitude training

Due to the reduced oxygen pressure at altitude, athletes are unable to maintain high intensity training and subsequently their aerobic fitness may slowly decrease. This reduction in fitness may offset any positive physiological adaptations from altitude exposure [High Alt Med Biol 2002; 3:177-93]. Moreover, athletes can become 'overtrained' as it is a common mistake to adopt the same training zone based on heart rates or times, time to perform a certain distance and/or lactate concentration.

At altitude, heart rate at rest and during submaximal exercise will increase proportionately to the level of altitude compared to sea level. With time after acclimatisation, the resting and submaximal heart rate will decrease a bit, but will still remain higher than sea-level values. In contrast a decrease or a similar heart rate during maximal exercise in hypoxic conditions is observed. In addition, training at altitude will result in higher levels of fatiguing lactate concentration; at a specific intensity of exercise, an altitude-induced performance impairment of about 3% has been observed in 1,500m running and of about 8% in 5,000 and 10,000m running compared to sea level. Similarly, impairments of 2-3% for 100m and 6-8% for 400m swimming or longer have been recorded [Can Med Assoc J. 1973; 109(3):207-9]. Therefore the sea level training standards cannot be used at altitude.

Another hazard is the cooler and dryer air at altitude; this dryness and the altitude-induced hyperventilation causes increase water loss via breathing (up to 1,900ml/day for a man and 850ml/for a woman). In addition, altitude-induced hormonal changes and the release of metabolites during the acclimatisation phase can increase the urine production by up to 500ml/day. It is very important therefore to drink sufficient fluid while sojourning at altitude (up to 5 litres per day) and reduce the use of caffeinated drinks, which can act as a mild diuretic.

Recovery from training is longer at altitude and since sleep can also be disturbed, a good way to avoid overtraining is to take an afternoon nap. Nutrition is also important; lower oxygen levels mean that demand for carbohydrate is proportionately higher and a healthy iron status is also desirable for the production of red blood cells. A nutrient-rich diet is also recommended to help counter the possibility of illness and infections due to the suppression of the immune system at altitude.

Acute mountain sickness - symptoms such as headache, vomiting, dizziness, physical and mental fatigue, sleep disturbance and digestive disorders can also occur at altitude and may require the reduction and modification of training, or even a complete cessation of training.

Last but not least, ultraviolet radiation is significantly higher at altitude and can cause sunburn or snow blindness. Athletes should therefore protect themselves by using ultraviolet sunscreen and sunglasses.

Temperature

The ability to perform vigorous exercise for long periods is limited by hyperthermia (over heating) and loss of water and salt in sweating. Athletes should know the hazards of vigorous exercise in hot, humid conditions and should be able to recognise the early warning symptoms that precede heat injury.

The circulatory system functions first to deliver nutrients to the working tissues and remove the waste products; and secondly to regulate the transfer of heat from active muscles to the body surface. It is because of this added demand on blood flow that body temperature regulation, and circulatory capacity, are significantly influenced by the environmental temperature and humidity. When performing in warm, humid conditions the circulation cannot both supply nutrients to muscle and regulate body temperature to the complete satisfaction of the body. As a result, the athlete's performance is impaired, and overheating becomes a serious problem.

Low levels of dehydration can influence performance and it is claimed that a loss of 2% bodyweight (1kg for a 50k athlete) can reduce performance by 10 to 20% (a 120 seconds 800 metres reduced to 132 to 144 seconds).

Two factors influencing early fatigue and impaired performance in all types of sports are the depletion of the body's levels of carbohydrate and fluids. Athletes should consider the use of sports drinks to replace these.

HEAT STROKE is one of the few potentially lethal complications of sport in a healthy individual.

Time

When we travel in an easterly or westerly direction, for every 15 degrees of longitude a time change of one hour occurs. The general effect of this time change is an upset to those body functions that are time-linked, e.g. sleeping, waking, eating, bowel and bladder functions. The body will gradually adjust and a minimum of one days stay for a one hours time change is regarded as a necessity. Travel by air also has an effect on the body. e.g. digestion upset, swelling feet and dehydration.

All Weather Training

Peak athletic performance is not just about getting the most out of your body; it is also about anticipating and meeting the various challenges thrown at you by different environmental conditions, including hot and cold climates, altitudinous terrain and polluted cities.

And it is about preparing yourself to be at your best at different times of the day and in far-flung time zones.

Select this link to order your copy of All Weather Training.

Associated Pages

The following Sports Coach pages should be read in conjunction with this page:

Associated Books

The following books provide more information related to this topic:

  • Principles of Anatomy and Physiology, G.J. Tortora et al., ISBN 0 06 046704 5
  • Strength Training Anatomy, F. Delavier, ISBN 0 7360 4185 0
  • Atlas of Skeletal Muscles, R.J. Stone et al., ISBN 0 697 13790 2
  • The Muscle Book, P. Blakey, ISBN 1 873017 00 6
  • Advanced Studies in Physical Education and Sport, P Beashel et al., ISBN 0 17 4482345
  • Physical Education and the Study of Sport, B. Davis et al., ISBN 0 7234 31752
  • Essentials of Exercise Physiology, W.D. McArdle et al., ISBN 0 683 30507 7
  • Physical Education and Sport Studies, D. Roscoe et al., ISBN 1 901424 20 0
  • The World of Sport Examined, P. Beashel et al., ISBN 0 17 438719 9
  • Advanced PE for Edexcel, F. Galligan et al., ISBN 0 435 50643 9
  • Examining Physical Education, K. Bizley, ISBN 0 435 50660 9
  • Sport and PE, K Wesson et al., ISBN 0 340 683821
  • PE for you, J. Honeybourne, ISBN 0 7487 3277 2